The Marine Life Information Network

Temperature increase (local)

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

Evidence

Arndt (1989) suggested that Alkmaria romijni was a thermophilic species. Arndt (1989) reported an LT50 (the lethal temperature at which 50% of specimens die) after 24 hrs of 38.4°C at 5‰ 38.9°C at 10‰ and 40.45°C at 20‰, based on Nausch (1985, Fig. 3). Thermal tolerance increased with increasing salinity (Nausch, 1984; Arndt, 1989).  Alkmaria romijni also tolerated low temperature conditions and had a freezing LT50 of 4.4 min at -10°C (and 10‰) when acclimated at 10°C or 4.7 min when acclimated at 5°C (Nausch, 1984; Arndt, 1989). In comparison, Arndt (1989) also suggested that Streblospio shrubsoli (a species that often coexists with, and competes with, Alkmaria romijni) as also thermophilic as their tolerances were very similar (Nausch, 1984) while Hediste diversicolor and Fabricia stellaris were more thermophobic.

Sensitivity assessment.  The above evidence suggests that Alkmaria romijni is thermophilic with a wide tolerance of temperatures, which coupled with a distribution from the North Sea and the Baltic to Morocco, suggests that it is resistant of a change in temperate of 2°C for a year in UK waters. Similarly, it lives on the surface of sediment, in the lower intertidal and shallow subtidal, so may be exposed to warm summers and cold winters throughout its range, and a change in 5°C for a month may result in stress. Mortality may result where a thermal discharge coincides with the warmest months of the year, or from extreme winter events but no direct evidence was available.  Therefore, a resistance of ‘High’ is suggested. Hence, resilience is ‘High’ and the species is recorded as ‘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

Arndt (1989) suggested that Alkmaria romijni was a thermophilic species. Arndt (1989) reported an LT50 (the lethal temperature at which 50% of specimens die) after 24 hrs of 38.4°C at 5‰ 38.9°C at 10‰ and 40.45°C at 20‰, based on Nausch (1985, Fig. 3). Thermal tolerance increased with increasing salinity (Nausch, 1984; Arndt, 1989).  Alkmaria romijni also tolerated low temperature conditions and had a freezing LT50 of 4.4 min at -10°C (and 10‰) when acclimated at 10°C or 4.7 min when acclimated at 5°C (Nausch, 1984; Arndt, 1989). In comparison, Arndt (1989) also suggested that Streblospio shrubsoli (a species that often coexists with, and competes with, Alkmaria romijni) as also thermophilic as their tolerances were very similar (Nausch, 1984) while Hediste diversicolor and Fabricia stellaris were more thermophobic.

Sensitivity assessment.  The above evidence suggests that Alkmaria romijni is thermophilic with a wide tolerance of temperatures, which coupled with a distribution from the North Sea and the Baltic to Morocco, suggests that it is resistant of a change in temperate of 2°C for a year in UK waters. Similarly, it lives on the surface of sediment, in the lower intertidal and shallow subtidal, so may be exposed to warm summers and cold winters throughout its range, and a change in 5°C for a month may result in stress. Mortality may result where a thermal discharge coincides with the warmest months of the year, or from extreme winter events but no direct evidence was available.  Therefore, a resistance of ‘High’ is suggested. Hence, resilience is ‘High’ and the species is recorded as ‘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

Ruso et al. (2007) reported that changes in the community structure of soft sediment communities due to desalinization plant effluent in Alicante, Spain. In particular, in close vicinity to the effluent, where the salinity reached 39 psu, the community of polychaetes, crustaceans and molluscs was lost and replaced by one dominated by nematodes. Roberts et al. (2010b) suggested that hypersaline effluent dispersed quickly (within 10s of metres of the outfall) but was more of a concern at the seabed and in areas of low energy where widespread alternations in the community of soft sediments were observed. In several studies, echinoderms and ascidians were amongst the most sensitive groups examined (Roberts et al., 2010b). Alkmaria romijni has been recorded form salinities of 5 to 48 psu but it's preferred range is thought to be 5 to 20 ppt since most records and the highest abundances are recorded in the latter range (Gilliland & Sanderson, 2000).

Sensitivity assessment. An increase in salinity from full to >40 psu is may result in a reduction in the abundance Alkmaria romijni of over a period of a year (the benchmark). However, no direct no direct evidence of the effects of hypersaline conditions or effluent on the species was found. Therefore, ‘No evidence’ was recorded.

Salinity decrease (local)

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

Evidence

Alkmaria romijni is considered to be a brackish water species Arndt (1989). It is known from salinities of 5 to 48 ppt, but it's preferred range is thought to be 5 to 20 ppt since most records and the highest abundances are recorded in the latter range (Gilliland & Sanderson, 2000). In the Ria de Avereiro (Portugal) Alkmaria romijni reached its highest abundances in areas of low salinity (18-30 or 5-18, Fig 3) close to freshwater input (Rodrigues et al., 2011). In the Arade river estuary (Portugal) (Silva et al., 2012), it was also found close to freshwater input but was ubiquitous throughout the estuary and not a good indicator of the influence of groundwater in the system.

Resilience assessment. Alkmaria romijni has a wide salinity tolerance (Gilliland & Sanderson, 2000). Therefore, it would probably be resistant of a change from ‘full’ or ‘variable’ salinity to ‘reduced’, or from ‘reduced’ to ‘low’ salinity regimes for a year, and may even benefit and increase in abundance due to loss of competition, and a resistance of ‘High’ is recorded. Hence, resilience is ‘High’ and the species is recorded as ‘Not sensitive’ at the benchmark level. However, a change to freshwater conditions may result in loss of species.

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

Alkmaria romijni is only recorded from muddy sediments in lagoons, estuaries and other transitional waters that are sheltered from wave action and with weak tidal streams (e.g. <0.5 m/s). A further decrease in water flow is unlikely.  However, an increase in water flow may result in mobilization of the sediment surface and removal of the species from the sediment surface. It is likely to result in modification of the sediment over a period of a year to more sandy and coarse sediments that are less suitable for the species. Therefore, while a 0.1-0.2 m/s change is small, the resultant change in the sediment, removal of fines, and potentially a proportion of the species' population, suggests a resistance of 'Low'.  Resilience is probably 'High' and sensitivity of 'Low' is recorded.

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

Gilliland and Sanderson (2000) suggest that Alkmaria romijni is intolerant of long periods of emersion based on its preference for the lower littoral and shallow sublittoral. Therefore, a decrease in emergence (an increase in the time covered by the tide) would probably allow the species to colonize sediments further up thee shore and expand its range. However, an increase in emergence is likely to reduce the upper limit of the species on the shore and, hence, reduce its range. Therefore, a resistance of 'Low' is suggested. Resilience is probably 'High' and sensitivity of 'Low' is recorded.

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

Alkmaria romijni is only recorded from muddy sediments in lagoons, estuaries and other transitional waters that are sheltered to extremely sheltered from wave action and with weak tidal streams (e.g. <0.5 m/s). A further decrease in wave action is unlikely.  However, an increase in wave action may result in mobilization of the sediment surface and removal of the species from the sediment surface. It is likely to result in modification of the sediment over a period of a year to more sandy and coarse sediments that are less suitable for the species. Although a 3-5% change in significant wave height is small, the resultant change in the sediment, removal of fines, and potentially a proportion of the species' population, suggests a resistance of 'Medium'.  Resilience is probably 'High' and sensitivity of 'Low' is recorded.

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

This pressure is Not assessed.

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

This pressure is Not assessed.

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

This pressure is Not assessed.

Radionuclide contamination

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

Evidence

No evidence was found

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

This pressure is Not assessed.

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

Nausch (1984) reported an LT50 (50% mortality)  after 50 hours in anoxic conditions (oxygen free water) at 5°C but 32 hrs at 10°C. The addition of hydrogen sulphide reduced the LT50 to 33.2 hrs and 17.2 hrs respectively (Nausch, 1984).  Cardoso et al. (2004) noted that algal mats of Ulva (as Enteromorpha) intestinalis resulted in a slight decline in the abundance of Alkmaria romijni, and that algal mats reduced the redox potential of the sediment (a sign of increased anoxia) but suggested that the decline in abundance of the species was due to the algal mats' interference with feeding. In several studies, Alkmaria romijni is associated with organically enriched sediments and eutrophic conditions (Borja et al., 2000; Cardoso et al., 2004b, 2007; Teixeira et al., 2009; Rodrigues et al., 2011). Organic-rich sediments tend to be hypoxic, although the species lives at the sediment surface exposed to passing water flow. In the Ria de Aveiro (Portugal) Alkmaria romijni reached its highest abundances in areas with a redox potential of 47.7 mV (Rodrigues et al., 2011).

Sensitivity assessment. Alkmaria romijni achieves high abundances in organic-rich sediments, and in areas subject to eutrophication, and is probably exposed to low oxygen levels in the sediment. Therefore, it is probably resistant of a short-term reduction in oxygen levels below 2 mg/l (see benchmark) and a resistance of 'High' is recorded. Hence, resilience is 'High' and the species is probably 'Not sensitive' at the benchmark level.

Nutrient enrichment

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

Evidence

Alkmaria romijni is associated with organically enriched sediments and eutrophic conditions (Borja et al., 2000; Cardoso et al., 2004b, 2007; Teixeira et al., 2009; Rodrigues et al., 2011).  Rodrigues et al. (2011) noted that Alkmaria romijni reached high abundance in the assemblage associated with increased organic content, increased fines and reduced hydrodynamic characteristics. Cardoso et al. (2004) noted that algal mats of Ulva (as Enteromorpha) intestinalis resulted in a slight decline in the abundance of Alkmaria romijni, and that algal mats reduced the redox potential of the sediment (a sign of increased anoxia) but suggested that the decline in abundance of the species was due to the algal mats' interference with feeding. Borja et al. (2000) placed Alkmaria romijni in AMBI category III, "species tolerant of excess organic matter enrichment; that occur under normal conditions but their populations are stimulated by enrichment". Teixeira et al. (2009) noted that the changes in ecological quality and recovery in Mondego estuary were better represented by the AMBI when Alkmaria romijni was classified in AMBI category IV, "second order opportunistic species". Cardoso et al. (2007) noted that Alkmaria romijni and Capitella capitata were indicators of organically enriched habitats and reached their highest abundances in the eutrophic areas of the estuary. Cardoso et al. (2007) noted that both species decreased in abundance after management was put in place in the 1990s to reduce eutrophication of the Mondego estuary.

Resilience assessment. Several studies suggest that Alkmaria romijni occurs and benefits from eutrophic conditions. Excessive growth of algal mats may reduce its abundance slightly (Cardoso et al., 2004). The benchmark is relatively protective and is not set at a level that would allow blooms of green algae on the sediment, hence, resistance is assessed as 'High' and resilience as 'High' (by default) so that the biotope is assessed as 'Not sensitive' at the benchmark level.

Organic enrichment

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

Evidence

Alkmaria romijni is associated with organically enriched sediments and eutrophic conditions (Borja et al., 2000; Cardoso et al., 2004b, 2007; Teixeira et al., 2009; Rodrigues et al., 2011).  Rodrigues et al. (2011) noted that Alkmaria romijni reached high abundance in the assemblage associated with increased organic content, increased fines and reduced hydrodynamic characteristics.   Borja et al. (2000) placed Alkmaria romijni in AMBI category III, "species tolerant of excess organic matter enrichment; that occur under normal conditions but their populations are stimulated by enrichment". Teixeira et al. (2009) noted that the changes in ecological quality and recovery in Mondego estuary were better represented by the AMBI when Alkmaria romijni was classified in AMBI category IV, "second order opportunistic species". Cardoso et al. (2007) noted that Alkmaria romijni and Capitella capitata were indicators of organically enriched habitats and reached their highest abundances in the eutrophic areas of the estuary. Cardoso et al. (2007) noted that both species decreased in abundance after management was put in place in the 1990s to reduce eutrophication of the Mondego estuary.

Resilience assessment.  Alkmaria romijni is associated with naturally organic-rich sediments, benefits as a result of organic enrichment, and is an indicator of organic enrichment. Therefore, a resistance of 'High' is recorded with a resilience of 'High' and the species is recorded as 'Not sensitive'. 

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 habitat (resilience is ‘Very low’). Sensitivity within the direct spatial footprint of this pressure is therefore ‘High’. Although no specific evidence is described, confidence in this assessment is ‘High’ due to the incontrovertible nature of 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

The species lives in sediment so a change to an artificial or rock substratum would result in the loss of its habitat. Based on the loss of species habitat (substratum), resistance is assessed as ‘None’, resilience is assessed as ‘Very low’ (as the change at the pressure benchmark is permanent), and sensitivity is assessed as ‘High’. Although no specific evidence is described, confidence in this assessment is ‘High’ due to the incontrovertible nature of this pressure.

Physical change (to another sediment type)

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

Evidence

Alkmaria romijni is recorded from muddy sediments, including muddy sands and muddy gravels. A change in sediment type from to sands or coarse sediments would result in loss of suitable habitat for the species. Therefore, a resistance of 'None' is recorded. Resilience is assessed as ‘Very low’ (as the change at the pressure benchmark is permanent), and sensitivity is assessed as ‘High’. Although no specific evidence is described, confidence in this assessment is ‘High’ due to the incontrovertible nature of this pressure.

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

Alkmaria romijni lives at the sediment surface in a tube of only two to three centimetres in length. Removal of 30 cm of the sediment would remove the entire population in the affected area. Therefore,  a resistance of 'None' is recorded. Recovery will depend on the recovery of the sediment itself and subsequent colonisation. Therefore a resilience of 'Medium' is recorded and sensitivity is assessed as 'Medium'.

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

Alkmaria romijni lives at the sediment surface in a tube of only two to three centimetres in length. It is soft-bodied but small (3-5 mm in length). Physical disturbance via abrasion to the sediment surface, or via penetrative gear or activities is likely to damage and kill a proportion of the population depending on the size of the footprint of the activity. Therefore, a resistance of 'Low' is suggested, although no direct evidence was found. The resilience is probably 'High' and a sensitivity of 'Low' is recorded. 

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

Alkmaria romijni lives at the sediment surface in a tube of only two to three centimetres in length. It is soft-bodied but small (3-5 mm in length). Physical disturbance via abrasion to the sediment surface, or via penetrative gear or activities is likely to damage and kill a proportion of the population depending on the size of the footprint of the activity. Therefore, a resistance of 'Low' is suggested, although no direct evidence was found. The resilience is probably 'High' and a sensitivity of 'Low' is recorded. 

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

Alkmaria romijni is found at the surface of muddy sediments in low energy environments with low water flow, sheltered from wave action. It is also considered an indicator of organically enriched sediments and occurs in eutrophic habitats and in estuaries where turbidity can be high (Cole et al., 1999).  Therefore, an increase in suspended sediment at the benchmark level is unlikely to be detrimental. A decrease in turbidity might be detrimental, as Cardoso et al. (2007) reported that the density of Alkmaria romijni decreased after mitigation measures were implemented in the Mondego estuary to reduce eutrophication and hence turbidity and organic loads.  However, a decrease in turbidity alone was not the cause of the decline but rather the reduction in the organic content of the sediment and competition from larger polychaetes (Cardoso et al., 2007).  In naturally organic-rich sediments, and changes in suspended sediment loads is unlikely to be detrimental. Therefore, resistance is assessed as 'High', resilience as 'High' and sensitivity recorded as 'Not sensitive' at the benchmark level.

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

Alkmaria romijni lives at the sediment surface in a tube of only two to three centimetres in length. It is soft-bodied but small (3-5 mm in length). It is found in low energy environments (low water flow, sheltered from wave action) so any deposited sediment is likely to remain for many tidal cycles.  No information on its ability to burrow was found. However, Maurer et al. (1986) noted that mucous tube feeders and labial palp deposit feeders (such as Alkmaria romijni) were the most susceptible to the killing effects of burial.  Therefore, burial by 5 cm of fine deposit (the benchmark) is likely to result in at least some mortality and a resistance of 'Medium' is recorded, albeit with low confidence. Resilience is probably 'High' so that sensitivity is assessed as 'Low'. 

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

Alkmaria romijni lives at the sediment surface in a tube of only two to three centimetres in length. It is soft-bodied but small (3-5 mm in length). It is found in low energy environments (low water flow, sheltered from wave action) so any deposited sediment is likely to remain for many tidal cycles.  No information on its ability to burrow was found. However, Maurer et al. (1986) noted that mucous tube feeders and labial palp deposit feeders (such as Alkmaria romijni) were the most susceptible to the killing effects of burial.  Therefore, burial by 30 cm of fine deposit (the benchmark) is likely to result in at least significant mortality and a resistance of 'Low' is recorded, albeit with low confidence. Resilience is probably 'High' so that sensitivity is assessed as 'Low'. 

Litter

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

Evidence

Not assessed

Electromagnetic changes

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

Evidence

No evidence was found

Underwater noise changes

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

Evidence

Not relevant

Introduction of light or shading

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

Evidence

Not relevant

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

Not relevant. This pressure is considered applicable to mobile species, e.g. fish and marine mammals rather than seabed habitats. Physical and hydrographic barriers may limit the dispersal of spores, larvae and other propagules. But propagule dispersal is not considered under the pressure definition and benchmarks,

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

Not relevant’ to seabed habitats.  NB. Collision by grounding vessels is addressed under ‘surface abrasion.

Visual disturbance

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

Evidence

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

No evidence of translocation, breeding or species hybridization was found.

Introduction or spread of invasive non-indigenous species

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

Evidence

Thomas & Thorpe (1994) recorded Alkmaria romijni, Nematostella vectensis and other benthic infauna in the vicinty of aggregations of the non-native polychaete Ficopomatus enigmaticus, in the Emsworth millpond complex, Chichester Harbour. However, the variation in abundance of Alkmaria romijni in their 10-year study was not explained by the presense of aggregations of Ficopomatus enigmaticus.

No evidence was found to suggest a positive or negative interaction between non-indigenous invasive species and Alkmaria romijni.

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 evidence of microbial pathogens was found. Alkmaria romijni was reported to host the trematode parasite Asymphylodora demeli (Margolis, 1971) but no information on its effect,  if any, at the population level was found.

Removal of target species

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

Evidence

Not relevant. This species is not subject to a targetted commercial or recreational fishery.

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

No evidence was found on the effects, if any, of commercial or recreational fishing on this species. However, it occurs in estuaries and transitional water bodies where it may be exposed to physical disturbance from a range of activities including, but not limited to, trawling, dredging, trampling and vehicular access, bait digging etc.  The sensitivity to such activities is addressed under the 'abrasion' and 'penetration' pressure above. Alkmaria romijni can reach high abundances in estuaries, lagoons and transitional waters, but no biological interactions are known. It has been reported to compete with Streblospio shrubsoli where they coexist (Arndt, 1989) but no evidence on the biological effects of its removal from the ecosystem was found.