The Marine Life Information Network

Global warming (extreme)

Extreme emission scenario (by the end of this century 2081-2100) benchmark of:

• A 5°C rise in SST and NBT (coastal to the shelf seas),

• A 6°C rise in surface air temperature (in eulittoral and supralittoral habitats).

• A 1°C rise in Deep-sea habitats (>200 m) off the continental shelf, and

• A 5°C rise in surface air temperature in intertidal habitats exclusive to Scotland. Further detail.

Evidence

Bottom water temperatures in areas off the continental shelf are expected to increase by a nominal 1°C under both the middle and high emission scenario. Munida is the most cosmopolitan and diverse genus of the Galatheids from the genus Munida spp. occupying a wide bathymetric range from shallow water down to more than 3,000 m depth (Wehrtmann et al., 2010). Each species appears to occupy overlapping, and yet distinct, depth ranges (Wehrtmann et al., 2010).  

Of the four species found in the NE Atlantic, three occur in the Mediterranean as well. Munida rugosa is known to inhabit shallow waters down to depths of 300 m in the NE Atlantic (Hartnoll et al., 1992) and Mediterranean (Ateş et al., 2005), whilst the species Munida intermedia is a small species which occurs at depths of 120 -800 m, from the UK to West Africa in the Eastern Atlantic, including the Mediterranean and the Adriatic Seas (Gramitto & Froglia, 1998). Munida sarsi is the most northern of the NE Atlantic species, being distributed from Norway to the Bay of Biscay, and is found at depths of 200 – 1000 m, although its most common depth distribution is between 250 – 450 m (Rice & de Saint Laurent, 1986). Munida tenuimana has the deepest depth distribution, occurring from 250 m, although rarely seen above 550 m depth, down to 1775 m, and is distributed from Iceland and Norway, down to the coast of Spain, Portugal, and into the Mediterranean (Rice & de Saint Laurent, 1986)

Experimental exposure to a sharp 10°C increase in water temperatures from 5 to 15°C led to increased oxygen consumption, and week-long exposure resulted in mortality in the deep water squat lobsters; Munida rugosa and Munida sarsi (Zainal et al., 1992). This suggests these species are sensitive to large changes in temperature, although this experimental increase is significantly higher than the temperature increase expected for the bathyal by the end of this century, and hence isn’t taken into consideration in the scoring.

Sensitivity Assessment. Three of the four NE Atlantic species of Munida sp. occur in the Mediterranean, suggesting that they will be able to withstand a 1°C temperature increase, and Munida intermedia (which is found at its northern limit in the UK) may actually benefit. Munida sarsi is a cold water species and may be the species most affected by a temperature rise, although it does have a more southerly distribution than the UK (occurring in the Bay of Biscay), and is likely to be able to withstand a small temperature increase of 1°C. If the abundance of this species did decrease in response to this temperature rise, it is likely that one of the other species would increase their abundance accordingly. As such, under all three scenarios (middle and high emission and extreme scenarios) resistance of this biotope has been assessed as ‘High’ and their resilience assessed as ‘High’ so that this biotope is considered ‘Not sensitive’ to ocean warming at the benchmark level. 

Global warming (high)

High emission scenario (by the end of this century 2081-2100) benchmark of:

• A 4°C rise in SST, NBT (coastal to the shelf seas) and surface air temperature (in eulittoral and supralittoral habitats).

• A 1°C rise in Deep-sea habitats (>200 m) off the continental shelf, and

• A 3°C rise in surface air temperature in intertidal habitats exclusive to Scotland. Further detail.

Evidence

Bottom water temperatures in areas off the continental shelf are expected to increase by a nominal 1°C under both the middle and high emission scenario. Munida is the most cosmopolitan and diverse genus of the Galatheids from the genus Munida spp. occupying a wide bathymetric range from shallow water down to more than 3,000 m depth (Wehrtmann et al., 2010). Each species appears to occupy overlapping, and yet distinct, depth ranges (Wehrtmann et al., 2010).  

Of the four species found in the NE Atlantic, three occur in the Mediterranean as well. Munida rugosa is known to inhabit shallow waters down to depths of 300 m in the NE Atlantic (Hartnoll et al., 1992) and Mediterranean (Ateş et al., 2005), whilst the species Munida intermedia is a small species which occurs at depths of 120 -800 m, from the UK to West Africa in the Eastern Atlantic, including the Mediterranean and the Adriatic Seas (Gramitto & Froglia, 1998). Munida sarsi is the most northern of the NE Atlantic species, being distributed from Norway to the Bay of Biscay, and is found at depths of 200 – 1000 m, although its most common depth distribution is between 250 – 450 m (Rice & de Saint Laurent, 1986). Munida tenuimana has the deepest depth distribution, occurring from 250 m, although rarely seen above 550 m depth, down to 1775 m, and is distributed from Iceland and Norway, down to the coast of Spain, Portugal, and into the Mediterranean (Rice & de Saint Laurent, 1986)

Experimental exposure to a sharp 10°C increase in water temperatures from 5 to 15°C led to increased oxygen consumption, and week-long exposure resulted in mortality in the deep water squat lobsters; Munida rugosa and Munida sarsi (Zainal et al., 1992). This suggests these species are sensitive to large changes in temperature, although this experimental increase is significantly higher than the temperature increase expected for the bathyal by the end of this century, and hence isn’t taken into consideration in the scoring.

Sensitivity Assessment. Three of the four NE Atlantic species of Munida sp. occur in the Mediterranean, suggesting that they will be able to withstand a 1°C temperature increase, and Munida intermedia (which is found at its northern limit in the UK) may actually benefit. Munida sarsi is a cold water species and may be the species most affected by a temperature rise, although it does have a more southerly distribution than the UK (occurring in the Bay of Biscay), and is likely to be able to withstand a small temperature increase of 1°C. If the abundance of this species did decrease in response to this temperature rise, it is likely that one of the other species would increase their abundance accordingly. As such, under all three scenarios (middle and high emission and extreme scenarios) resistance of this biotope has been assessed as ‘High’ and their resilience assessed as ‘High’ so that this biotope is considered ‘Not sensitive’ to ocean warming at the benchmark level. 

Global warming (middle)

Middle emission scenario (by the end of this century 2081-2100) benchmark of:

• A 3°C rise in SST, NBT (coastal to the shelf seas) and surface air temperature (in eulittoral and supralittoral habitats).

• A 1°C rise in Deep-sea habitats (>200 m) off the continental shelf.

• A 2°C rise in surface air temperature in intertidal habitats exclusive to Scotland. Further detail.

Evidence

Bottom water temperatures in areas off the continental shelf are expected to increase by a nominal 1°C under both the middle and high emission scenario. Munida is the most cosmopolitan and diverse genus of the Galatheids from the genus Munida spp. occupying a wide bathymetric range from shallow water down to more than 3,000 m depth (Wehrtmann et al., 2010). Each species appears to occupy overlapping, and yet distinct, depth ranges (Wehrtmann et al., 2010).  

Of the four species found in the NE Atlantic, three occur in the Mediterranean as well. Munida rugosa is known to inhabit shallow waters down to depths of 300 m in the NE Atlantic (Hartnoll et al., 1992) and Mediterranean (Ateş et al., 2005), whilst the species Munida intermedia is a small species which occurs at depths of 120 -800 m, from the UK to West Africa in the Eastern Atlantic, including the Mediterranean and the Adriatic Seas (Gramitto & Froglia, 1998). Munida sarsi is the most northern of the NE Atlantic species, being distributed from Norway to the Bay of Biscay, and is found at depths of 200 – 1000 m, although its most common depth distribution is between 250 – 450 m (Rice & de Saint Laurent, 1986). Munida tenuimana has the deepest depth distribution, occurring from 250 m, although rarely seen above 550 m depth, down to 1775 m, and is distributed from Iceland and Norway, down to the coast of Spain, Portugal, and into the Mediterranean (Rice & de Saint Laurent, 1986)

Experimental exposure to a sharp 10°C increase in water temperatures from 5 to 15°C led to increased oxygen consumption, and week-long exposure resulted in mortality in the deep water squat lobsters; Munida rugosa and Munida sarsi (Zainal et al., 1992). This suggests these species are sensitive to large changes in temperature, although this experimental increase is significantly higher than the temperature increase expected for the bathyal by the end of this century, and hence isn’t taken into consideration in the scoring.

Sensitivity Assessment. Three of the four NE Atlantic species of Munida sp. occur in the Mediterranean, suggesting that they will be able to withstand a 1°C temperature increase, and Munida intermedia (which is found at its northern limit in the UK) may actually benefit. Munida sarsi is a cold water species and may be the species most affected by a temperature rise, although it does have a more southerly distribution than the UK (occurring in the Bay of Biscay), and is likely to be able to withstand a small temperature increase of 1°C. If the abundance of this species did decrease in response to this temperature rise, it is likely that one of the other species would increase their abundance accordingly. As such, under all three scenarios (middle and high emission and extreme scenarios) resistance of this biotope has been assessed as ‘High’ and their resilience assessed as ‘High’ so that this biotope is considered ‘Not sensitive’ to ocean warming at the benchmark level. 

Marine heatwaves (high)

High emission scenario benchmark: A marine heatwave occurring every two years, with a mean duration of 120 days, and a maximum intensity of 3.5°C. Further detail.

Evidence

Marine heatwaves caused by increased air-sea flux of heat are only expected to penetrate surface waters (≤ 50 m) (Cerrano et al., 2000, Garrabou et al., 2009; Dan Smale, pers. comms.) Therefore, sensitivity to marine heatwaves is probably ‘Not relevant’ in this bathyal habitat.

Marine heatwaves (middle)

Middle emission scenario benchmark:  A marine heatwave occurring every three years, with a mean duration of 80 days, with a maximum intensity of 2°C. Further detail.

Evidence

Marine heatwaves caused by increased air-sea flux of heat are only expected to penetrate surface waters (≤ 50 m) (Cerrano et al., 2000, Garrabou et al., 2009; Dan Smale, pers. comms.) Therefore, sensitivity to marine heatwaves is probably ‘Not relevant’ in this bathyal habitat.

Ocean acidification (high)

High emission scenario benchmark: a further decrease in pH of 0.35 (annual mean) and corresponding 120% increase in H+ ions , seasonal aragonite saturation of 20% of UK coastal waters and North Sea bottom waters, and the aragonite saturation horizon in the NE Atlantic, off the continental shelf, occurring at a depth of 400 m by the end of this century 2081-2100. Further detail 

Evidence

The absorption of carbon dioxide from the atmosphere and the resultant decrease in pH leads to changes in the carbonate chemistry of the oceans; an increase in hydrogen ions and a decrease in carbonate ions, which are needed for calcification. When the aragonite saturation state falls below 1, shells, coral skeleton, and other aragonitic structures start to dissolve.  This results in the shoaling of the aragonite saturation horizon (ASH). The ASH is defined as the depth in the oceans at which aragonite saturation equals 1. Below this depth, the aragonite saturation state (Ω_Ar) will fall below 1, and dissolution of calcified structures that are not protected by living tissue (e.g. coral reef and fragments) may occur. Currently, the depth of the ASH in the North Atlantic is approximately 2000m (Jiang et al., 2015) but this depth is already 80-150 m shallower than the past two centuries (Chung et al., 2003, Feely et al., 2004). By the end of this century, the ASH is expected to reach depths of up to 400 m under the high emission scenario (RCP 8.5) and 600 m for the middle emission scenario (RCP 4.5) (Zheng & Long, 2014).

Little is known of the effects of ocean acidification on squat lobsters, although at a submarine canyon off the coast of Australia, Munidopsis sp. has been found living at depths of 1357 m, >300 m below the ASH (Trotter et al., 2019). Whilst this is the only literature which describes the depth of a squat lobster in relation to the aragonite saturation state, the fact that species from the genus Munida are found at depths of more than 3000 m suggests that this genus is likely to be robust to future ocean acidification, even if the ASH does rise to the upper bathyal.

The abundance of squat lobsters is most likely intrinsically linked to the heterogeneity of the coral rubble and gravel in which this group of animals resides within this biotope. Squat lobsters often have a symbiotic lifestyle with their habitat and two species are commonly associated with Lophelia pertusa reef and rubble; Munida rugosa and Munidopsis serricornis (Baeza, 2011). Habitat complexity mediates predator-prey interactions through the provision of refuges (Rogers et al., 2014), and there is a strong positive relationship between complexity and species density and biomass (Graham & Nash, 2013). For Lophelia pertusa, both areas of live coral and areas of coral rubble enhance species density, compared to areas with no coral framework (Jonsson et al., 2004).

In an experiment, Voight (2010) looked at the dissolution of dead Lophelia pertusa rubble fragments in response to different aragonite saturation states. After 50 days, minimal dissolution was seen at Ω_Ar 1.02, but dissolution became more apparent at Ω_Ar 0.71 – 0.55 (Voigt, 2010). Furthermore, Hennige et al. (2015) observed dissolution of the exposed skeleton at aragonite saturation states < 1 and found that Lophelia pertusa coral framework became 20-30% weaker at low pH, even before saturation state fell below 1 (Ω_Ar 1.19-1.09). Extensive coral graveyards have been observed below the aragonite saturation horizon in Australia, which are thought to have flourished during the last ice age 18 – 33 thousand years ago (Trotter et al., 2019), suggesting that aragonite undersaturation will not cause complete dissolution and total loss of habitat.

Sensitivity Assessment. As squat lobsters such as Munida sp. rely on coral rubble for provision of heterogeneous habitat, they are likely to be impacted by the dissolution of the rubble and simplification of the habitat. There is evidence that some squat lobsters, including species from the genus Munida, live at depths where the aragonite saturation state is < 1, and this genus is therefore expected to be tolerant to ocean acidification. Therefore, under the middle emission scenario (0.15 unit decrease in pH), the aragonite saturation horizon (ASH) is not expected to reach the upper bathyal (200-600 m) or the shelf seas (<200 m)  (Zheng & Long, 2014), and hence Lophelia pertusa rubble is not expected to suffer any dissolution. Therefore, resistance is assessed as ‘High’, resilience as ‘High’ and sensitivity is assessed as ‘Not sensitive’ at this benchmark.  Under the high emission scenario (0.35 unit decrease in pH), the ASH saturation state is predicted to rise to approximately 400 m, reaching the upper bathyal, and could lead to some dissolution of the coral rubble and a reduction in habitat structure, although it is likely that the squat lobsters themselves will be tolerant of this reduction in pH.  Therefore, resistance has been assessed as ‘Medium’ as it is assumed that sufficient habitat would remain to support the squat lobster assemblage.  Resilience has been assessed as ‘Very Low’ due to the long-term nature of ocean acidification, and, hence, sensitivity is assessed as ‘Medium’. 

Ocean acidification (middle)

Middle emission scenario benchmark: a further decrease in pH of 0.15 (annual mean) and corresponding 35% increase in H+ ions with no coastal aragonite undersaturation and the aragonite saturation horizon in the NE Atlantic, off the continental shelf, at a depth of 800 m by the end of this century 2081-2100. Further detail.

Evidence

The absorption of carbon dioxide from the atmosphere and the resultant decrease in pH leads to changes in the carbonate chemistry of the oceans; an increase in hydrogen ions and a decrease in carbonate ions, which are needed for calcification. When the aragonite saturation state falls below 1, shells, coral skeleton, and other aragonitic structures start to dissolve.  This results in the shoaling of the aragonite saturation horizon (ASH). The ASH is defined as the depth in the oceans at which aragonite saturation equals 1. Below this depth, the aragonite saturation state (Ω_Ar) will fall below 1, and dissolution of calcified structures that are not protected by living tissue (e.g. coral reef and fragments) may occur. Currently, the depth of the ASH in the North Atlantic is approximately 2000m (Jiang et al., 2015) but this depth is already 80-150 m shallower than the past two centuries (Chung et al., 2003, Feely et al., 2004). By the end of this century, the ASH is expected to reach depths of up to 400 m under the high emission scenario (RCP 8.5) and 600 m for the middle emission scenario (RCP 4.5) (Zheng & Long, 2014).

Little is known of the effects of ocean acidification on squat lobsters, although at a submarine canyon off the coast of Australia, Munidopsis sp. has been found living at depths of 1357 m, >300 m below the ASH (Trotter et al., 2019). Whilst this is the only literature which describes the depth of a squat lobster in relation to the aragonite saturation state, the fact that species from the genus Munida are found at depths of more than 3000 m suggests that this genus is likely to be robust to future ocean acidification, even if the ASH does rise to the upper bathyal.

The abundance of squat lobsters is most likely intrinsically linked to the heterogeneity of the coral rubble and gravel in which this group of animals resides within this biotope. Squat lobsters often have a symbiotic lifestyle with their habitat and two species are commonly associated with Lophelia pertusa reef and rubble; Munida rugosa and Munidopsis serricornis (Baeza, 2011). Habitat complexity mediates predator-prey interactions through the provision of refuges (Rogers et al., 2014), and there is a strong positive relationship between complexity and species density and biomass (Graham & Nash, 2013). For Lophelia pertusa, both areas of live coral and areas of coral rubble enhance species density, compared to areas with no coral framework (Jonsson et al., 2004).

In an experiment, Voight (2010) looked at the dissolution of dead Lophelia pertusa rubble fragments in response to different aragonite saturation states. After 50 days, minimal dissolution was seen at Ω_Ar 1.02, but dissolution became more apparent at Ω_Ar 0.71 – 0.55 (Voigt, 2010). Furthermore, Hennige et al. (2015) observed dissolution of the exposed skeleton at aragonite saturation states < 1 and found that Lophelia pertusa coral framework became 20-30% weaker at low pH, even before saturation state fell below 1 (Ω_Ar 1.19-1.09). Extensive coral graveyards have been observed below the aragonite saturation horizon in Australia, which are thought to have flourished during the last ice age 18 – 33 thousand years ago (Trotter et al., 2019), suggesting that aragonite undersaturation will not cause complete dissolution and total loss of habitat.

Sensitivity Assessment. As squat lobsters such as Munida sp. rely on coral rubble for provision of heterogeneous habitat, they are likely to be impacted by the dissolution of the rubble and simplification of the habitat. There is evidence that some squat lobsters, including species from the genus Munida, live at depths where the aragonite saturation state is < 1, and this genus is therefore expected to be tolerant to ocean acidification. Therefore, under the middle emission scenario (0.15 unit decrease in pH), the aragonite saturation horizon (ASH) is not expected to reach the upper bathyal (200-600 m) or the shelf seas (<200 m)  (Zheng & Long, 2014), and hence Lophelia pertusa rubble is not expected to suffer any dissolution. Therefore, resistance is assessed as ‘High’, resilience as ‘High’ and sensitivity is assessed as ‘Not sensitive’ at this benchmark.  Under the high emission scenario (0.35 unit decrease in pH), the ASH saturation state is predicted to rise to approximately 400 m, reaching the upper bathyal, and could lead to some dissolution of the coral rubble and a reduction in habitat structure, although it is likely that the squat lobsters themselves will be tolerant of this reduction in pH.  Therefore, resistance has been assessed as ‘Medium’ as it is assumed that sufficient habitat would remain to support the squat lobster assemblage.  Resilience has been assessed as ‘Very Low’ due to the long-term nature of ocean acidification, and, hence, sensitivity is assessed as ‘Medium’. 

Sea level rise (extreme)

Extreme scenario benchmark: a 107 cm rise in average UK by the end of this century (2018-2100). Further detail.

Evidence

At a depth of 200 – 600 m, these biotopes will not be affected by sea-level rise.  Therefore sensitivity to this climate change pressure is probably ‘Not relevant’ in this bathyal habitat.

Sea level rise (high)

High emission scenario benchmark: a 70 cm rise in average UK by the end of this century (2018-2100). Further detail.

Evidence

At a depth of 200 – 600 m, these biotopes will not be affected by sea-level rise.  Therefore sensitivity to this climate change pressure is probably ‘Not relevant’ in this bathyal habitat.

Sea level rise (middle)

Middle emission scenario benchmark: a 50 cm rise in average UK sea-level rise by the end of this century (2081-2100). Further detail.

Evidence

At a depth of 200 – 600 m, these biotopes will not be affected by sea-level rise.  Therefore sensitivity to this climate change pressure is probably ‘Not relevant’ in this bathyal habitat.

Temperature increase (local)

Benchmark. A 5°C increase in temperature for one month, or 2°C for one year. Further detail

Evidence

Munida sp. vary in their distribution and have different depth preferences within this distribution. Hartnoll et al. (1992) provide evidence on the species ranges. Munida rugosa is found down to about 300 m depth and occurs in the eastern Atlantic from Norway to Madeira and the Mediterranean (Hartnoll et al., 1992). Munida sarsi has been found from 100-1000 m depth (but commonly ~250-400 m) from Iceland, northern Norway and the Barents Sea, to the Bay of Biscay and northern Spain. It mainly occurs on the continental slope but has also been found in shallow fjords (Brinkmann, 1936; Zainal, 1990). Munida tenuimana has been reported from depths between ~120-1775 m and is distributed from Iceland, West Greenland, the Barents Sea and Norway, to the Iberian Peninsula and the Mediterranean. These distributions suggest a potentially wide temperature tolerance.

However, experimental studies indicate lower tolerances. Avalos et al. (2006) (in Romero et al. 2010), found that Munida gregaria doubled its oxygen consumption when the temperature was increased from 6 –18°C. Furthermore, a study by Zainal et al. (1992a) on samples of Munida rugosa and Munida sarsi collected from the Clyde Sea at depths of 40-115 m, found that oxygen consumption, heart rates and scaphognathite rates increased when subjected to increases in temperature from 10°C up to 20°C. The measured parameters then decreased progressively at increased temperatures of 20-25°C, with periods of cardiac arrest, but when returned to temperatures of 10°C, rates returned to normal after around 6-10 hours. However, if exposure exceeded 20°C for a prolonged period (>90 minutes), the species appeared stressed and mortality rates increased (Zainal et al., 1992a).

The study suggests that Munida rugosa and Munida sarsi do not normally experience wide temperature fluctuations in their natural environment, with temperatures of 7-10°C common in the Clyde Sea (Zainal et al., 1992a). These species were, therefore, more likely to experience oxygen deficiencies at increased temperatures, due to low oxygen affinities of the oxygen-storing protein haemocyanin (Zainal et al., 1992a).  

Reproductive efficacy and cycle have also been shown to be impacted by variations in temperature, with temperature acting as a trigger for reproductive development and growth. Vinuesa (2007b) reported that Munida gregoria in the subantarctic waters of the Beagle Channel and the San Jorge Gulf, Argentina, where temperatures vary from 4 to >8°C, show different reproductive regimes. Those in the San Jorge Gulf, at higher temperatures, have two spawnings within the same reproductive period, whereas those in the colder temperatures in the Beagle Channel have one spawning time (Tapella et al., 2002b).

Sensitivity assessment. Although the distribution of Munida sp. indicates they are tolerant to a range of temperatures, experimental evidence suggests oxygen consumption is affected by large temperature changes, with increases of >10°C resulting in stress and mortality (Zainal et al., 1992a). However, at the benchmark level of a 5°C increase in temperature for one month, or 2°C for one year, there is unlikely to be a significant effect on population viability. Therefore, resistance is assessed as ‘High’, resilience is ‘High’ and the biotope is considered ‘Not sensitive’ at the benchmark level. 

Temperature decrease (local)

Benchmark. A 5°C decrease in temperature for one month, or 2°C for one year. Further detail

Evidence

Munida sp. vary in their distribution and have different depth preferences within this distribution. Hartnoll et al. (1992) provide evidence on the species ranges. Munida rugosa is found down to about 300 m depth and occurs in the eastern Atlantic from Norway to Madeira and the Mediterranean (Hartnoll et al., 1992). Munida sarsi has been found from 100-1000 m depth (but commonly ~250-400 m) from Iceland, northern Norway and the Barents Sea, to the Bay of Biscay and northern Spain. It mainly occurs on the continental slope but has also been found in shallow fjords (Brinkmann, 1936; Zainal, 1990). Munida tenuimana has been reported from depths between ~120-1775 m and is distributed from Iceland, West Greenland, the Barents Sea and Norway, to the Iberian Peninsula and the Mediterranean. These distributions suggest a potentially wide temperature tolerance.

However, experimental studies indicate lower tolerances. Avalos et al. (2006) (in Romero et al. 2010), found that Munida gregaria doubled its oxygen consumption when the temperature was increased from 6 –18°C. Furthermore, a study by Zainal et al. (1992a) on samples of Munida rugosa and Munida sarsi collected from the Clyde Sea at depths of 40-115 m, found that oxygen consumption, heart rates and scaphognathite rates increased when subjected to increases in temperature from 10°C up to 20°C. The measured parameters then decreased progressively at increased temperatures of 20-25°C, with periods of cardiac arrest, but when returned to temperatures of 10°C, rates returned to normal after around 6-10 hours. However, if exposure exceeded 20°C for a prolonged period (>90 minutes), the species appeared stressed and mortality rates increased (Zainal et al., 1992a). However effects from decreases in temperature were not reported (Zainal et al., 1992a).

The study suggests that Munida rugosa and Munida sarsi do not normally experience wide temperature fluctuations in their natural environment, with temperatures of 7-10°C common in the Clyde Sea (Zainal et al., 1992a). These species were, therefore, more likely to experience oxygen deficiencies at increased temperatures, due to low oxygen affinities of the oxygen-storing protein haemocyanin (Zainal et al., 1992a). Reproductive efficacy and cycle have also been shown to be impacted by variations in temperature, with temperature acting as a trigger for reproductive development and growth. Vinuesa (2007b) reported that Munida gregoria in the subantarctic waters of the Beagle Channel and the San Jorge Gulf, Argentina, where temperatures vary from 4 to >8°C, show different reproductive regimes. Those in the San Jorge Gulf, at higher temperatures, have two spawnings within the same reproductive period, whereas those in the colder temperatures in the Beagle Channel have one spawning time (Tapella et al., 2002b).

Sensitivity assessment. Although the distribution of Munida sp. indicates they are tolerant to a range of temperatures, experimental evidence suggests oxygen consumption is affected by large temperature changes, with increases of >10°C resulting in stress and mortality (Zainal et al., 1992a). However, at the benchmark level of a 5°C increase in temperature for one month, or 2°C for one year, there is unlikely to be a significant effect on population viability. Therefore, resistance is assessed as ‘High’, resilience is ‘High’ and the biotope is considered ‘Not sensitive’ at the benchmark level. 

Salinity increase (local)

Benchmark. A increase in one MNCR salinity category above the usual range of the biotope or habitat. Further detail

Evidence

The squat lobster assemblages biotopes have been recorded at full salinity (JNCC, 2015, 2022) and changes in salinity are unlikely due to the depth at which the biotopes are found, combined with the distance from shore and the low potential for brine or freshwater discharge. However, there is some evidence that suggests that Munida spp. can tolerate a wide range of salinities. For example, Munida tenuimana has been recorded at Le Danois Bank in the Cantabrian Sea at depths of 800-1050 m and a bottom salinity of 35.77 (Sánchez et al., 2008). In estuarine environments, zoaea of Munida gregaria were found to be more tolerant to higher-salinity conditions (25-30) whereas megalopae were preferentially distributed in a wider range of salinity (10-34) (Meerhoff et al., 2013).

Sensitivity assessment. There is limited specific evidence on the effects of this pressure on this biotope and, therefore, the pressure is assessed as 'Insufficient evidence'.

Salinity decrease (local)

Benchmark. A decrease in one MNCR salinity category above the usual range of the biotope or habitat. Further detail

Evidence

The squat lobster assemblages biotopes have been recorded at full salinity (JNCC, 2015, 2022) and changes in salinity are unlikely due to the depth at which the biotopes are found, combined with the distance from shore and the low potential for brine or freshwater discharge. However, there is some evidence that suggests that Munida spp. can tolerate a wide range of salinities. For example, Munida tenuimana has been recorded at Le Danois Bank in the Cantabrian Sea at depths of 800-1050 m and a bottom salinity of 35.77 (Sánchez et al., 2008). In estuarine environments, the zoaea of Munida gregaria were found to be more tolerant to higher-salinity conditions (25-30) whereas megalopae were preferentially distributed in a wider range of salinity (10-34) (Meerhoff et al., 2013).

Sensitivity assessment. There is limited specific evidence on the effects of this pressure on this biotope and, therefore, the pressure is assessed as 'Insufficient evidence'.

Water flow (tidal current) changes (local)

Benchmark. A change in peak mean spring bed flow velocity of between 0.1 m/s to 0.2 m/s for more than one year. Further detail

Evidence

Cold-water coral bioherms are associated with strong water flows (Roberts et al., 2009). In particular, Lophelia pertusa reefs around the Lousy and Hatton Banks would typically encounter current speeds of 0.01-0.1 m/s (Frederiksen et al., 1992). Masson et al. (2003) recorded a maximum residual bottom water flow of 0.35 m/s over 20 days in the Darwin Mounds. In the Sula through (250-320 m) in the Norwegian Sea, where the current velocity was measured at 0.04-0.05 m/s, Munida sarsi was found at high density on Lophelia rubble of the parallel-current side (Mortensen et al., 1995). Therefore, this biotope probably experiences water flow higher than the benchmark and is unlikely to be adversely affected by a change in water flow at the benchmark level.  Hence, resistance is assessed as 'High', resilience as 'High' and sensitivity as 'Not sensitive' at the benchmark level. However, confidence in the assessment is 'Low' due to the lack of direct evidence. 

Emergence regime changes

Benchmark.  1) A change in the time covered or not covered by the sea for a period of ≥1 year or 2) an increase in relative sea level or decrease in high water level for ≥1 year. Further detail

Evidence

The squat lobster assemblage biotopes are found at upper and mid bathyal depths. Therefore, they will not be affected by changes in the emergence regime and the biotopes are assessed as ‘Not relevant’.

Wave exposure changes (local)

Benchmark. A change in near shore significant wave height of >3% but <5% for more than one year. Further detail

Evidence

The squat lobster assemblage biotopes are found at upper and mid bathyal depths. Therefore, they will not be affected by changes in nearshore wave exposure and the biotopes are assessed as ‘Not relevant’.

Transition elements & organo-metal contamination

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

No information on the effect of heavy metals on squat lobsters was found, and little is known about the effect of heavy metals on lobsters in general. However, a study investigated the impact of slag dumping from a ferronickel smelting plant in the North Evoikos Gulf (Greece) on the shallow crustacean Munida rugosa (Bordbar and Catsiki, 2015). North Evoikos Gulf is a final receiver of slag dumped from the most important ferronickel smelting plant in Europe. The purpose of this study is to investigate the impact of the slag on the metal concentration of the benthic\crustacean Munida rugosa. Muscle and gill samples of Munida rugosa collected from the slag dumping area and a reference area in June 2009 and March 2010 were measured for Fe, Ni, Cr, Mn, Zn and Cu by Flame and Graphite atomic absorption spectrometry. The results showed that the metal concentrations in gills were higher than in muscles. Females in most cases presented higher levels of metals than males. The North Evoikos Gulf and, in particular, the marine organisms were heavily impacted by the dumping slag and the functioning of the smelting plant since the reference area was as contaminated as the slag dumping (Bordbar & Catsiki, 2015). The study concluded that Munida rugosa individuals are directly exposed to the slag which gradually and constantly releases metal ions in the seawater and sediment. In particular, manganese, nickel, chromium and iron accumulated at 15 to 300 times higher concentrations in the gills than in muscle tissues for both sexes. The physiological impact of metal accumulation on Munida rugosa was not determined.

In the American lobster Homarus americanus high concentrations of cadmium (14 mg/l 96-hour LC50 and 56 mg/l 48-hour LC50) and Zinc (17 mg/l 96-hour LC50 and 35 mg/l 48-hour LC50) were reported to cause mortality (ECOTOX, Jan. 2024). However, larval stages were more sensitive and suffered mortality due to cadmium (110 µg/l 96-hour LC50 and 230 µg/l 48-hour LC50), zinc (0.5 mg/l 96-hour LC50 and 1 mg/l 48-hour LC50), thallium (1 mg/l 96-hour LC50 and 9 mg/l 48-hour LC50) and copper (46 µg/l 48-hour LC50) (ECOTOX, Jan. 2024). Similarly, Homarus vulgaris larvae exhibited mortality when exposed to cobalt (450 µg/l 9-day LC50). 

Laughlin & French (1980) reported that lobster larvae (Homarus americanus) were more sensitive to TBTO exposure than shore crab larvae (Hemigrapsus nudus). TBTO resulted in 100% larval mortality after 24 days at 20 µg/l. 

Sensitivity assessment. Heavy metal exposure in the North Evoikos Gulf was not reported to cause mortality in Munida spp.. However, heavy metal exposure did cause mortality in the larval stages of the American and blue lobster. Heavy metal tolerance is probably species-specific (Rainbow, 2002) and it is difficult to extrapolate based species from similar taxonomic groups. Similarly, the evidence on the effect of TBT is also limited. Therefore, heavy metals may be detrimental to squat lobsters, especially at high concentrations, but there is 'Insufficient evidence' on which to base an assessment at present.  

Hydrocarbon & PAH contamination

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

Crude oil exposure, even at a low concentration oil-seawater ratio of 1:100,000, has been observed to interfere with the chemosensory behaviour of the lobster, Homarus americanus by depressing appetite and chemical excitability, and increasing the time taken to find food (Atema & Stein, 1974). Water-soluble fraction of petroleum hydrocarbons is the most toxic to marine species, including lobsters. A crude oil concentration of 18 mg/l was shown to be lethal to all stages of Homarus americanus larvae in four days, with first-stage larvae showing a higher sensitivity (they became moribund in six hours) than fourth-stage larvae (Wells & Sprague, 1976). In 30-day tests, the effect of seven increasing concentrations of dispersed crude oil on the rate of larval development was that developmental time in high concentrations (e.g. 0.74 mg/l) was significantly longer than in the control group (0 mg/l). Under natural conditions, delayed development would keep lobster larvae planktonic for longer times, significantly increasing their exposure to predators and surface drift. Furthermore, those larvae that successfully moulted to the following stage consumed between 1.3 and 1.9 times less food than larvae in the control treatment (Wells & Sprague, 1976).

Exposure to Homarus americanus larvae to petroleum resulted in mortality (48-hour LC50 of 0.86, 4.6 and 4.9 mg/l) under laboratory conditions (ECOTOX, Jan 2023). Similarly, exposure of Homarus vulgaris adults to the dispersant BP1002 resulted in mortality (48-hour LC50 of 20 mg/l). Portmann & Connor (1968) examined the toxicity (48-hour LC50s) of 12 commercial 'oil spills' removers (dispersants) on Pandalus montagui, Crangon crangon, Cardium edule and Carinus maenas). Pandalus montagui was found to be the most susceptible of the four species (48-hour LC50 of 4.5 to 148 ppm depending on the dispersant). 

Valentine & Benfield (2013) examined epibenthic and demersal megafauna at 2000 m and 500 m from the Deepwater Horizon wellhead, using ROV transects. They noted that squat lobsters (as Galatheidae) were absent from two post-spill sites that also had the lowest taxonomic richness and abundance, 500 m N and 2000m E.  The 500m N site was in the soil stream from the well while it was unclear if the 2000 m E site was also affected by the spill. The lack of pre-spill surveys made it difficult to make clear conclusions.  

Exposure to the PAH fluoranthene under laboratory conditions resulted in significant mortality to Homarus americanus larvae (96-hour LC50 of 317 µg/l or 13 µg/l in the presence of UV light), the amphipod (Ampelisca abdita)  juveniles (96-hour LC50 of 67 µg/l) and the mysid (Mysidopsis bahia) juveniles (96-hour LC50 of 31 µg/l or 1.4 µg/l in the presence of UV light) (Spehar et al., 1999). The authors concluded that crustaceans were the most sensitive to fluoranthene, but the presence of UV light increased the relative sensitivity of oligochaetes and one of the fish species tested. 

Sensitivity assessment. The above evidence suggests that exposure to crude oil, petroleum, and dispersants can result in significant mortality in lobsters, and by inference squat lobsters. Larval exposure to the PAH fluoranthene also caused significant mortality in several species of crustaceans.  Therefore, resistance is assessed as 'Low', albeit with 'Low' confidence due to the lack of direct evidence in squat lobsters.  Resilience is probably 'High' so sensitivity is assessed as 'Low'. 

Synthetic compound contamination

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

Many synthetic compounds such as pesticides and pharmaceuticals target specific biochemical, hormonal or metabolic pathways as part of their action. As such pathways are often conserved within taxonomic groups, lobsters are probably susceptible to insecticides as Crustaceans and Insects share similar biochemical pathways, and pesticides and pharmaceuticals that adversely affect some crustaceans may be presumed to affect other crustaceans. Most studies of pesticides and pharmaceutical toxicity have been conducted in lobsters. For example: 

• Zulkosky et al. (2005) reported that the pesticides (malathion, resmethrin and methoprene) used to treat the mosquitos that carried the West Nile virus in New York in 1999 resulted in the collapse of the American lobster population in western Long Island Sound. Stage I-II larval lobsters were extremely sensitive to continuous resmethrin exposure. Resmethrin LC50s for larval lobsters (under flow-through conditions) varied from 0.26–0.95 μg/l in 48-hour and 96-hour experiments at 16°C, respectively. Malathion and methoprene were less toxic than resmethrin. The 48-hour LC50 for malathion was 3.7 μg/l and methoprene showed no toxicity at the highest (10 μg/l) concentration tested. Only sublethal responses were reported for juvenile lobsters after seven days of exposure. 
• The pesticide Dimecron resulted in significant mortality in spiny lobster Palinurus argus (96-hour LC50 of 0.3 mg/l) (ECOTOX, Jan 2024).
• Pahl & Opitz (1999) reported a 12-hour LC50 in Homarus americanus larvae of 0.365 to 1.69 ppb for cypermethrin exposure at 12°C and 0.9-50.4 ppb for azamethiphos exposure at 12°C. The authors noted that the lowest LC50s were significantly lower than the recommended treatment concentrations. 
• McHenery et al. (1991) reported a 96-hour LC50 of 5.7 µg/l after exposure of Homarus gammarus larve to dichlorvos in the laboratory. They noted that larvae were sensitive to low concentrations of dichlorvos but recovered from sublethal concentrations.
• Burridge et al. (2014) exposed lobsters (Homarus americanus) and shrimp to the pesticides AlphaMax® (deltamethrin), Salmosan® (azamethiphos) and Interox®Paramove™50(hydrogen peroxide) for one or 24-hours and determined their lethal thresholds. Deltamethrin was the most toxic with LC50s in ng/l (e.g. adult lobster 24-hour LC%0 of 15 ng/l). The next toxic was azamethiphos with an adult lobster 24-hour LC50 of 2.8 µg/l. Hydrogen peroxide was the least toxic (adult lobster 24-hour LC50 greater than 3,750 mg/l). 

Marine litter may represent a direct and indirect vehicle for the introduction and release of chemical substances into the marine environment and the organisms inhabiting it. Some xenobiotics, such as persistent organic pollutants, heavy metals, pesticides, and pharmaceuticals are resistant to degradation and deep waters and sediments have been suggested as the final sink for such pollutants with long-term consequences (Canals et al., 2020). The effect of polychlorinated biphenyls (PCBs)-spiked microplastics ingestion by wild-caught Nephrops norvegicus was studied under laboratory conditions (Devriese et al., 2017). The authors reported no negative effect on the nutritional state of Nephrops nor accumulation of PCBs in its tissues. Considering that squat lobsters have a similar feeding behaviour, it is highly likely that they also ingest microplastics and are exposed to contaminated sediments. 

Sensitivity assessment. The above evidence suggests that crustaceans are sensitive to insecticides and laboratory exposure results in significant mortality. Therefore, resistance is assessed as 'Low'.  Resilience in squat lobsters is probably 'High' due to their short lifespan, annual reproduction and rapid sexual maturation. Hence, sensitivity is assessed as 'Low' but with 'Medium' confidence due to the lack of evidence on the potential effects of larval mortality on the population dynamics of squat lobster populations.  

Radionuclide contamination

Benchmark. An increase in 10µGy/h above background levels. Further detail

Evidence

No information on the effect of radionuclide contamination on this biotope was found, and little is known about the effect of radionuclide contamination on squat lobsters in general. Therefore, this pressure is assessed as ‘No evidence’

Introduction of other substances

Benchmark. Exposure of marine species or habitat to one or more relevant contaminants via uncontrolled releases or incidental spills. Further detail

Evidence

'No evidence' was found on the effects of this pressure on squat lobsters.

De-oxygenation

Benchmark. Exposure to dissolved oxygen concentration of less than or equal to 2 mg/l for one week (a change from WFD poor status to bad status). Further detail

Evidence

Squat lobster assemblages occur in deep water and the cold, open ocean waters that bathe the shelf margin and slope, which are typically well oxygenated. Depending on the feeding habits (predation vs deposit feeding) and sex, squat lobsters can have different rates of oxygen consumption. A study conducted in the Beagle Channel demonstrated that female predatory Munida gregaria consumed less oxygen than males per unit time to assimilate any type of food regardless of the feeding strategy. In general, as predators, squat lobsters consumed significantly more oxygen than as deposit feeders (Romero et al., 2010).

In Saanich Inlet on southern Vancouver Island, Canada, shallow-dwelling Munida quadrispina was found to be very tolerant of hypoxia, with high densities found at oxygen levels as low as 0.1 to 0.15 ml/l (Matabos et al., 2012). However, the gill mass of individuals living in hypoxic conditions exceeded that of those in oxic conditions, suggesting the ability of local adaptations to low oxygen concentrations (Matabos et al., 2012). Furthermore, only larger individuals of Munida quadrispina with well developed gills can tolerate severe oxygen depletion (<0.15 ml/l), while smaller ones could only be found in the areas with higher oxygen content (>2.0 ml/l) (Burd, 1988; Burd & Brinkhurst, 1984). Although Munida spp. can tolerate prolonged hypoxic conditions, Zainal et al. (1992b) found that neither Munida rugosa nor Munida sarsi were tolerant of anoxia. Munida rugosa could survive in total anoxia for eight hours, while Munida sarsi could only survive four hours.

Sensitivity assessment. Squat lobster assemblages occur in well-oxygenated areas. However, adult squat lobsters are more tolerant to hypoxic conditions than smaller or juvenile lobsters. Total anoxia will certainly lead to the death of individuals. Therefore, resistance is assessed as ‘Medium’, and resilience is assessed as ‘High’. Overall, squat lobster assemblage biotopes are considered to have ‘Low’ sensitivity to this pressure.

Nutrient enrichment

Benchmark. Compliance with WFD criteria for good status. Further detail

Evidence

By definition, the biotopes are considered to be 'Not sensitive' at the pressure benchmark, which assumes compliance with good status as defined by the WFD.

Organic enrichment

Benchmark. A deposit of 100 gC/m²/yr. Further detail

Evidence

Organic enrichment can lead to nutrient enrichment and deoxygenation. Organic enrichment encourages the productivity of suspension and deposit feeding detrivores and allows species to colonise the affected area to take advantage of the enriched food. However, ‘No evidence’ specific to this biotope was found.

Physical loss (to land or freshwater habitat)

Benchmark. A permanent loss of existing saline habitat within the site. Further detail

Evidence

All marine habitats and benthic species are considered to have a resistance of ‘None’ to this pressure and to be unable to recover from a permanent loss of available habitat (resilience is ‘Very low’). The squat lobster assemblage biotopes are therefore considered to have ‘High’ sensitivity to this pressure.

Physical change (to another seabed type)

Benchmark. Permanent change from sedimentary or soft rock substrata to hard rock or artificial substrata or vice-versa. Further detail

Evidence

A change from sediment to hard rock substratum is likely to impact the characterizing species and the physical habitat. As dead coral debris defines the biotopes, a change in sediment type will result in a change in the biotope classification and therefore the loss of the original biotope. Hence, resistance is assessed as 'None'. As this pressure is considered a permanent change, resilience is assessed as 'Very Low', and sensitivity is, therefore, assessed as 'High'.

Physical change (to another sediment type)

Benchmark. Permanent change in one Folk class (based on UK SeaMap simplified classification). Further detail

Evidence

A change in sediment type will result in a change in the biotope classification and, therefore, the loss of the original biotope, so resistance is assessed as ‘None’. As this pressure is considered a permanent change, resilience is assessed as 'Very Low', and the biotope is considered to have ‘High’ sensitivity to a change in seabed type by one Folk class.

Habitat structure changes - removal of substratum (extraction)

Benchmark. The extraction of substratum to 30 cm (where substratum includes sediments and soft rock but excludes hard bedrock). Further detail

Evidence

In this biotope, rubble left by dead Lophelia provides the habitat for squat lobsters. In the Haltenbanken-Frøyabanken area (Norwegian Sea), Lophelia bioherms occur at depths of 250-320 m. Lophelia pertusa rubble habitat was found to cover around 60% of the area in depths of 280-300 m and had four times higher density of Munida sarsi lobsters (four individuals /10m² on average) compared to areas with dead or living Lophelia, and soft or mixed stone sediments (Mortensen et al., 1995). Extraction of substratum to 30 cm within this biotope would result in the removal of the main habitat feature, and therefore, the loss of the biotope.

Sensitivity assessment. This biotope has no resistance to the removal of the substratum of 30 cm, therefore, resistance is assessed as ‘None’. The extremely long-lived nature and slow growth of Lophelia pertusa means that the replacement of a sufficient amount of dead coral rubble from adjacent living reefs would make recovery slow. Hence, the resilience is ‘Very low’, and the biotope is considered to have ‘High’ sensitivity to this pressure.

Abrasion / disturbance of the surface of the substratum or seabed

Benchmark. Damage to surface features (e.g. species and physical structures within the habitat). Further detail

Evidence

Damage to seabed surface is mainly caused by bottom trawling activities which alter the local environment by scraping, ploughing and resuspending sediment and physically destroying, removing or scattering benthic organisms. However, the significance of wider area impacts is hard to assess due to the lack of data on rates of recovery after disturbance in deep water.

A study in the Peru Basin, SE Pacific, investigated the impact of manganese nodule mining by ploughing the seabed at 4,000 m depth on the megabenthos. A purpose-built 8 m wide plough-harrow device was used to penetrate the sediment by up to 15 cm. The megabenthos were surveyed immediately after the seabed disturbance, after six months and finally three years after impact (Bluhm et al., 1995). It was observed that highly motile species such as crustaceans were able to escape the ploughing device and recolonized the disturbed sediment within three years (Bluhm et al., 1995).

A study by Buhl-Mortensen et al. (2016) reviewed the impacts of otter trawling and fishing intensity on the shelf (50-400 m) and slope (400-2,000 m) habitats of the southern Barents Sea. The study found that fishing intensity negatively, but insignificantly, affected the density of Munida sarsi within mud habitats. Bergmann et al. (2001a) found that trawling of Nephrops norvegicus in the Clyde Sea caused damage to Munida rugosa. The most common injury was the loss of one chela, but they were also shown to lose the second pereiopod and often sustained damages to the carapace in the form of holes in the shell.

Sensitivity assessment. Overall, there is evidence of damage to squat lobster assemblages from surface disturbance and other physical disturbances of the substratum. Although squat lobsters are motile species and can avoid trawling equipment to some extent, the coral rubble substratum is likely to be severely impacted, if not removed or redistributed. Therefore, resistance is assessed as ‘Low’ to represent at least partial loss of coral rubble, and resilience is ‘Very low’ due to the time taken for the substratum to be replaced from the adjacent living coral reef. Hence, sensitivity is assessed as 'High'.  However, confidence in the assessment is 'Medium' as the assessment is based on the effects on similar species but not similar habitats. 

Penetration or disturbance of the substratum subsurface

Benchmark. Damage to sub-surface features (e.g. species and physical structures within the habitat). Further detail

Evidence

Penetration and or disturbance of the substratum would result in similar if not identical effects as the Abrasion pressure (above). 

Sensitivity assessment. Overall, there is evidence of damage to squat lobster assemblages from surface disturbance and other physical disturbances of the substratum. Although squat lobsters are motile species and can avoid trawling equipment to some extent, the coral rubble substratum is likely to be severely impacted, if not removed or redistributed. Therefore, resistance is assessed as ‘Low’ to represent at least partial loss of coral rubble, and resilience is ‘Very low’ due to the time taken for the substratum to be replaced from the adjacent living coral reef. Hence, sensitivity is assessed as 'High'.  However, confidence in the assessment is 'Medium' as the assessment is based on the effects on similar species but not similar habitats. 

Changes in suspended solids (water clarity)

Benchmark. A change in one rank on the WFD (Water Framework Directive) scale e.g. from clear to intermediate for one year. Further detail

Evidence

Munida spp. are found in a variety of sedimentary habitats, including depositional habitats such as burrowed mud. In addition, they can feed on a range of different food stuffs from particulate organic matter and marine snow to carrion and smaller invertebrates (Poore et al., 2011). Therefore, they are probably adapted to a range of suspended sediment loads. In addition, coral bioherms are associated with strong water flow so that suspended sediment may not accrete on the seabed. Therefore, resistance is assessed as 'High', resilience as 'High' and sensitivity as 'Not sensitive', albeit at 'Low' confidence due to the lack of direct evidence. 

Smothering and siltation rate changes (light)

Benchmark. ‘Light’ deposition of up to 5 cm of fine material added to the seabed in a single discrete event. Further detail

Evidence

Squat lobsters can burrow in soft sediment, so it can be assumed that the deposition of fine material at the pressure benchmark would not affect the squat lobster assemblages. The levels of water flow within this environment are recorded to be sufficient to re-suspend or remove sediment relatively quickly. The resistance of this biotope to the pressure at the benchmark is assessed as ‘High’, resilience as ‘High’, and overall sensitivity as ‘Not sensitive’.

Smothering and siltation rate changes (heavy)

Benchmark. ‘Heavy’ deposition of up to 30 cm of fine material added to the seabed in a single discrete event. Further detail

Evidence

Jones et al. (2007) observed that seabed spoil from oil and gas drilling had a smothering effect on the deep-sea megabenthic habitat at two hydrocarbon fields, Foinaven and Schiehallion, in the Faroe-Shetland Channel. The most dominant species at both sites was Munida sarsii. In Foinaven, the drill spoils were constrained to approximately 50 m from the drill sites, while in the Schiehallion field, the extent of spoils was greater than 150 m from the drill sites. The drill spoils had a smothering effect which negatively impacted the abundance and diversity of motile organisms in areas close to the disturbance source (<50 m), particularly within production structures. Beyond 50 m from the source of disturbance, there were no significant differences in motile megafaunal abundance. Outside of the disturbed area, the seabed consisted of a heterogeneous mix of sand, gravel and occasionally larger cobbles and boulders that positively affected the total faunal abundance and diversity (Jones et al., 2007).

Sensitivity assessment. Although squat lobsters can burrow in soft sediment and are unlikely to be affected significantly by deposition of 30 cm, the heavy deposition of fine material will alter the biotope substratum structure. If the sediment were to remain in place for a prolonged time (depending on water flow), this could result in a change in the biotope classification and therefore the loss of the original biotope. Sediment deposition could fill spaces in between the coral rubble and reduce niches for squat lobsters. Freiwald et al., (2004) noted that Munida abundance was higher in the coral rubble than in the surrounding sediment, hence, their abundance may decrease. Hence, resistance is assessed as 'Low' and resilience is assessed as 'Low', resulting in overall sensitivity being 'High'.

Litter

Benchmark. The introduction of man-made objects able to cause physical harm (surface, water column, seafloor or strandline). Further detail

Evidence

Marine benthic litter varies substantially between marine areas and tends to accumulate mostly in deep-sea canyons and open slopes (Company et al., 2012; Mordecai et al., 2011). In the Bay of Biscay, for example, litter has been observed in 15 canyons, 42% of which was made of plastic (i.e. bags and sheets), 16.2% was related to fishing gear, and 6.1% was classified as other or unidentified (van den Beld et al., 2017). In the Mediterranean Sea, the density of marine litter in depths greater than 100 m can average 5.2 items per 100 m² with fishing gear being the dominant source of litter (98%) (Consoli et al., 2018). Litter items such as plastic, fishing gear, ropes and cloth were found to be colonized by Lophelia pertusa corals, likely providing a growing substratum for coral colonies. It was also observed that Munida spp. used plastic items and cloth as burrows instead of digging into the sediment (van den Beld et al., 2017). Munida tenuimana was observed to use large rolling oil metal drums, a Roman amphora, and metal cans as shelters in the Cap de Creus Canyon (Northwestern Mediterranean Sea) floor at a depth of up to 1,545 m (Tubau et al., 2015).

Microplastics accumulate in deep-sea sediments where they can be ingested by deep-sea organisms and affect individual fitness with consequences for reproduction and survival (Kuhn et al., 2015). Direct evidence for microplastic ingestion by Munida was not found, but a recent study has demonstrated through laboratory experiments that wild-caught Norwegian langoustine Nephrops norvegicus (402-656 m in Sardinia, Mediterranean Sea) ingests microplastics, 65% of which were made of polyethylene, polypropylene, and polystyrene (Cau et al., 2020). Nephrops norvegicus recovered from the Clyde Sea have been seen to contain large aggregations of microplastic fibres anterior to the gastric mill and the narrowing at the entrance to the hindgut, which can cause false satiation and starvation in highly affected individuals (Welden & Cowie, 2016a, 2016b). Furthermore, microplastic fibres ingested at high concentrations (25 fibres per ml) have been shown to cause decreased early larval survival of the American lobster, Homarus americanus, and reduced oxygen consumption (Woods et al., 2020). It is highly likely that Munida also ingest microplastics given the similarity in feeding physiology and habitats with Nephrops and Homarus. However, no direct evidence for Munida was available on the effects of microplastic pollution.

Sensitivity assessment. Although certain types of litter such as fishing gear can damage and/or entangle existing Lophelia pertusa corals, it can also provide a substrate for the growth of new coral and shelter for Munida spp., which is a motile species and can avoid macro litter to a large extent. However, there is no evidence of the wider ecological effects of litter on the squat lobster assemblages. The sensitivity is assessed as 'Insufficient evidence', pending further evidence. 

Electromagnetic changes

Benchmark. A local electric field of 1 V/m or a local magnetic field of 10 µT. Further detail

Evidence

No evidence could be found on the effects of Electromagnetic changes on the characterizing species. Therefore, this pressure is assessed as ‘No evidence’.

Underwater noise changes

Benchmark. MSFD indicator levels (SEL or peak SPL) exceeded for 20% of days in a calendar year. Further detail

Evidence

Decapod crustaceans do not have gas-filled spaces within their bodies and the sensitivity of lobsters to different acoustic frequencies remains largely unknown. However, the European spiny lobster Palinurus elaphas can emit acoustic signals within the range of ultrasonic frequencies (2-75 kHz) most probably in the anti-predator (Buscaino et al., 2011) or territorial and courtship context (Stocker, 2002). Anthropogenic noise such as shipping noise pollution has been shown to significantly affect behavioural activity (expressed as increased locomotor behaviour) and haemolymphatic bioindicator for stress in Palinurus elaphas (Filiciotto et al., 2014). Haemolymphatic biochemistry is a bioindicator of stressful conditions and poor health in crustaceans  (Edmonds et al., 2016). When exposed to acoustic stress from boats (random sequence of boat noises, including recreational boats, hydrofoils, fishing boats and ferry boats) under laboratory conditions, the number of circulating haemocytes (THC) in Palinurus elaphas was about 38% lower than in non-exposed lobsters (Celi et al., 2014). Suppressed haemocyte numbers may increase the risk of infections by opportunistic and/or pathogenic microorganisms. However, the physiological responses to in-situ noise exposure of lobsters where the acoustical field is closer to that of the natural environment remains to be determined.

Anthropogenic continuous broadband sound (equivalent to a ship at a distance of ~ 100 m; sound pressure level of 135-140 dB re 1µPa) and impulsive broadband sound (equivalent to a wind farm mono-pile being driven on the North Sea at a distance of ~ 60 m; sound exposure levels of 150 dB re 1 µPa²s) have been shown to repress burying and bio-irrigation behaviour in the commercially important Nephrops norvegicus (Solan et al., 2016). However, scaling the individual impacts of anthropogenic noise to community and system-level effects remains challenging.

Sensitivity assessment. The above evidence suggests that anthropogenic noise can cause stress and alter behaviour in lobster species but the effects on the community remain undetermined. Therefore, in the absence of direct evidence, 'Insufficient evidence' is recorded, pending further evidence. 

Introduction of light or shading

Benchmark. A change in incident light via anthropogenic means. Further detail

Evidence

Decapod crustaceans have compound eyes and, therefore, have quite good vision. However, at the depths at which this biotope occurs, it is unlikely that the species will be affected by natural light.  Nevertheless, populations of Munida tenuimana have been shown to demonstrate depth-dependent (i.e. above or below the twilight zone) burrow-emergence rhythms up to 1,500 m depth in the Western Mediterranean (Aguzzi et al., 2013). Nocturnal maxima occurred between 400 and 900 m, and there was a shift in the timing of catch maxima with increasing depth. The maxima occurred in the second half of the night and in the morning at 1,200 m, during the day at 1,500 m, and the pattern was less defined at 1,300 m depth (Aguzzi et al., 2013). The authors also suggested that Munida developed phenotypic traits driven by visual predation using solar light (i.e. within the twilight zone range) and bioluminescence (i.e. in the aphotic deep-sea) to hunt. In particular, squat lobsters had low levels of spectral reflectance meaning that they were hard to see under blue or green bioluminescence. There was also a transition in squat lobster colour from sand-like to more reddish as depth increased. Red pigments contribute to the ‘invisibility’ of deep-sea animals since red colour can absorb blue-green wavelengths from direct bioluminescence predators exposure.  However, unnatural light sources from oil and gas platforms, subsea infrastructure, and other forms of exploration equipment and removal of resources can be introduced to this biotope and potentially alter the burrow-emergence behaviour of squat lobsters and make them visible to predators. However, there is no evidence to support an assessment at this pressure benchmark and, therefore, an assessment of ‘Insufficient evidence’ is recorded.

Barrier to species movement

Benchmark. A permanent or temporary barrier to species movement over ≥50% of water body width or a 10% change in tidal excursion. Further detail

Evidence

Despite being a mobile species, squat lobsters do not move around a lot and are mostly sedentary and population subdivision results from lack of gene flow via larval dispersal. This pressure is considered applicable to mobile species such as fish and marine mammals rather than seabed habitats. Physical and hydrographic barriers may limit the dispersal of larvae but larval dispersal is not considered under the pressure definition and benchmark. Therefore, this pressure is described as ‘Not relevant’.

Death or injury by collision

Benchmark. Injury or mortality from collisions of biota with both static or moving structures due to 0.1% of tidal volume on an average tide, passing through an artificial structure. Further detail

Evidence

The squat lobster assemblage biotopes are unlikely to be affected by an increased risk of collision defined under the pressure. This pressure is assessed as ‘Not relevant’.

Visual disturbance

Benchmark. The daily duration of transient visual cues exceeds 10% of the period of site occupancy by the feature. Further detail

Evidence

Decapod crustaceans have compound eyes and, therefore, have quite good vision. However, at the depths at which this biotope occurs, it is unlikely that the species will be affected by visual disturbance as defined under this pressure. Therefore, this pressure is described as ‘Not relevant’.

Genetic modification & translocation of indigenous species

Benchmark. Translocation of indigenous species or the introduction of genetically modified or genetically different populations of indigenous species that may result in changes in the genetic structure of local populations, hybridization, or change in community structure. Further detail

Evidence

None of the characterizing species associated with the squat lobster assemblage biotopes are subject to cultivation or translocation, so this pressure is considered ‘Not relevant’.

Introduction or spread of invasive non-indigenous species

Benchmark. The introduction of one or more invasive non-indigenous species (INIS). Further detail

Evidence

The commercially important red king crab Paralithodes camtschaticus has, over the past decades invaded the northernmost coast of Norway after its intentional introduction to coastal waters near Murmansk, Russia in the 1960s. The red king crab is one of the largest crabs in the world and feeds on a wide range of benthic infauna, epifauna and algae (Falk-Pederson et al., 2011). There is a concern that the red king crab in the Barents Sea may compete with native anomurans and brachyurans.  The diet of juvenile and adult red king crabs overlaps with that of native species including Munida rugosa and Munida sarsi (Stubner et al., 2016). Paralithodes camtschaticus has not yet been reported in the UK. Therefore, there is ‘Insufficient evidence’ currently on the effects of this non-native species on squat lobster assemblages.

Introduction of microbial pathogens

Benchmark. The introduction of relevant microbial pathogens or metazoan disease vectors to an area where they are currently not present (e.g. Martelia refringens and Bonamia, Avian influenza virus, viral Haemorrhagic Septicaemia virus). Further detail

Evidence

No information on diseases was found. However, the parasitic epicaridean bopyrid Pleucocrypta sp. was reported growing in the gill chambers of Munida rutllanti in the Adriatic Sea (Petrić et al., 2010). Infected specimens had lower body weight than uninfected specimens. The position of the parasite inside the host caused deformation in the carapace width, which was higher in the parasitized individuals than in the uninfected ones. In general, infected specimens had lower body weight than uninfected specimens. Some infected male squat lobsters displayed modifications in the secondary sex characteristics expressed in the feminisation of cheliped growth and proportions (Petrić et al., 2010). The authors also observed that Pleurocrypta sp. suppressed functional oogenesis in infected females, enabling final maturation and hatching of eggs and in males, it delayed the maturation of spermatozoa and formation of spermatophore for a season. However, given the small prevalence of the bopyrid (~ 8%) in the M. rutllanti, it is highly unlikely that there would be a severe effect on the whole host population dynamics.  Therefore, the pressure is assessed as ‘Insufficient evidence’.

Removal of target species

Benchmark. Removal of species targeted by fishery, shellfishery or harvesting at a commercial or recreational scale. Further detail

Evidence

Well-established squat lobster fisheries are currently found exclusively in Latin America, especially in Chile (Poore et al., 2011). It is not a commercially or recreationally targeted species in the North-East Atlantic, so the pressure on this biotope is assessed as ‘Not relevant’.

Removal of non-target species

Benchmark. Removal of features or incidental non-targeted catch (by-catch) through targeted fishery, shellfishery or harvesting at a commercial or recreational scale. Further detail

Evidence

The squat lobster Munida rugosa is a common crustacean species in the Nephrops trawl fishery bycatch in Scotland and has been identified as one of the most abundant decapod species discarded from the fishery in the Clyde Sea area (Bergmann & Moore, 2001). They reported that approx. 60% of Munida rugosa caught by commercial trawls show signs of injury, such as loss of appendages, likely caused by physical impacts from the gear itself, other species, or handling. Munida rugosa can also deliberately remove appendages to escape or reduce damage, which may affect survival rates (Bergmann & Moore, 2001). Post-fishing mortality can be enhanced by prolonged catch-sorting periods, which most commonly last for 90 min. During the sorting period, animals endure hypoxia, temperature changes, high light intensities, and physical damage due to handling and compression by the weight of the catch. On average, 14% of trawl-caught Munida rugosa died on deck and 57% of all Munida rugosa sustained damage. Loss of one chela was the most frequent damage sustained (37%) followed by loss of pereiopods (17-20%), and an injury to the carapace (9%) (Bergmann et al., 2001). The post-trawling long-term survival rate (after 90 min exposure to air) of injured lobsters was the highest during the first week of the recovery period (21 days) but was two times higher than in undamaged trawled animals and those caught in creels. The overall mortality of trawled Munida rugosa was in the range of 16-32% (Bergmann & Moore, 2001). In other areas, Munida sp. has also been commonly identified as bycatch from trawling for other species. For example, Tapella et al. (2002b) observed Munida subrugosa was the main bycatch species when trawling for shrimp Pleoticus muelleri and king crab Lithodes santolla; Favaro et al. (2010) found Munida quadrispina was the most abundant bycatch in the spot prawn traps in British Columbia; Smith (2012) found that Munida quadrispina was one of the most abundant bycatches in the spot prawn Pandalus platyceros fishery in Alaska, and Varisco et al. (2015) also found Munida gregaria was an important component of the bycatch in shallow (<50 m depth) bottom trawling fisheries in San Jorge Gulf, Argentina.

Sensitivity assessment. Therefore, resistance to the removal of non-target species is assessed ‘Low’ as evidence suggests that Munida sp. are highly susceptible to removal as bycatch within trawls. Resilience is probably ‘Low’ and sensitivity is, therefore, assessed as ‘High’.