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

No information on the temperature tolerance of Siphonoecetes spp. was found. Centraloecetes kroyeranus (syn. Siphonoecetes (Centraloecetes) kroyeranus; syn Siphonoecetes kroyeranus) (Myers & MacGrath, 1979; Just, 2017) is recorded from northern Norway, south, into the Mediterranean but most of the records occur in the North Sea, around the coasts of the British Isles, France and Spain as far east as the Kattegat near the entrance to the Baltic (OBIS, 2022). Therefore, it is probably resistant to the range of temperatures experienced to the north and south of the British Isles. Therefore, resistance is assessed as 'High', resilience as 'High' and sensitivity as 'Not sensitive', but with 'Low' confidence. 

Temperature decrease (local)

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

Evidence

No information on the temperature tolerance of Siphonoecetes spp. was found. Centraloecetes kroyeranus (syn. Siphonoecetes (Centraloecetes) kroyeranus; syn Siphonoecetes kroyeranus) (Myers & MacGrath, 1979; Just, 2017) is recorded from northern Norway, south, into the Mediterranean but most of the records occur in the North Sea, around the coasts of the British Isles, France and Spain as far east as the Kattegat near the entrance to the Baltic (OBIS, 2022). Therefore, it is probably resistant to the range of temperatures experienced to the north and south of the British Isles. Therefore, resistance is assessed as 'High', resilience as 'High' and sensitivity as 'Not sensitive', but with 'Low' confidence. 

Salinity increase (local)

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

Evidence

De-la-Ossa-Carretero et al. (2016b) examined the amphipod communities of sand habitats in the vicinity of harbour, sewage, and brine discharges from the Port of Alicante, Spain. While the abundance f amphipods declined near the discharges, some species (i.e. Gammarella fucicola, Ampelisca spinipes, Siphonoecetes bulborostrum and Pseudolirius kroyeri were abundant in the transect closest to the harbour and sewage discharge). However, amphipods were absent in the vicinity of the brine discharge, whose salinity was in excess of 39 psu in 2004 and 2005. But the abundance of amphipods increased and was dominated by Siphonoecetes sabatieri in the station closest to the brine discharge after it was diluted in 2006 (De-la-Ossa-Carretero et al., 2016b). 

Sensitivity assessment.  The evidence suggests that Siphonoecetes spp. and other amphipods are probably very sensitive to hypersaline effluent. Therefore, resistance is assessed as 'None'. In the example above (Port of Alicante), Siphonoecetes sp. was abundant in the surrounding area so recruitment into the site was rapid (probably one year). However, this biotope is only recorded in a few isolated locations, so resilience is assessed as 'Medium'.  Hence, sensitivity is assessed as 'Medium'. 

Salinity decrease (local)

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

Evidence

This biotope (SS.SSa.CFiSa.SiphNephVen) is only recorded from full salinity (30-35). Centraloecetes kroyeranus (syn. Siphonoecetes (Centraloecetes) kroyeranus) was recorded from sites with full salinity(30-35 psu) with only a small number of records from reduced (18-30 psu) conditions.  In the absence of other evidence, this species complex is probably limited to marine waters. Therefore, it probably has a 'Low' resistance to a reduction in salinity at the benchmark level. However, resilience is probably 'High' so sensitivity is assessed as 'Low' but with 'Low' confidence due to the lack of direct 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

This biotope (SS.SSa.CFiSa.SiphNephVen) is only recorded from moderate tidal steams (0.5-1.5 m/sec) and moderately exposed wave conditions. Siphonoecetes spp. are recorded from medium and coarse sandy bottoms (Myers & McGrath, 1979; Mora, 1991; Moreira et al., 2008; De-la-Ossa-Carretero et al., 2015), predominately sand with little mud on the Dogger Bank (Reiss & Kröncke, 2005) and fine sands (Bigot et al., 2006). Therefore, the biotope and the dominant characteristic species are dependent on the hydrographic conditions suitable for the deposition and presence of fine to coarse sands. A decrease in water flow by 0.1-0.2 m/s might increase the deposition of fine silts and muds in areas of the biotope with the lowest water flow, although that may be offset by the moderate wave action that characterizes the biotope. Similarly, an increase in flow may remove some fine sands but as it normally occurs between 0.5 and 1.5 m/s, such an increase is probably not significant.  Therefore, resistance to changes in water flow is probably 'High' at the benchmark level. Hence, resilience is 'High' and sensitivity is assessed as 'Not sensitive' at the benchmark level. 

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

This biotope (SS.SSa.CFiSa.SiphNephVen) is only recorded from 20-30 metres. Hence, this pressure is '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

This biotope (SS.SSa.CFiSa.SiphNephVen) is only recorded from moderate tidal steams (0.5-1.5 m/sec) and moderately exposed wave conditions. Siphonoecetes spp. are recorded from medium and coarse sandy bottoms (Myers & McGrath, 1979; Mora, 1991; Moreira et al., 2008; De-la-Ossa-Carretero et al., 2016b), predominately sand with little mud on the Dogger Bank (Reiss & Kröncke, 2005) and fine sands (Bigot et al., 2006). Therefore, the biotope and the dominant characteristic species are dependent on the hydrographic conditions suitable for the deposition and presence of fine to coarse sands. A change in significant wave height of 3-5% (the benchmark) is unlikely to be significant in the wave regime that characterizes this biotope. Hence, resistance to changes in wave action is probably 'High',  resilience is 'High', and sensitivity is assessed as 'Not sensitive' at the benchmark level. 

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

Little direct evidence of the effects of transitional metals on Siphonoecetes spp. was found.  Guerra-García & García-Gómez (2004) compared amphipod communities inside the harbour of Ceuta, North Africa, with communities outside the harbour. Siphonoecetes dellavallei dominated the amphipod community outside the harbour in sandy sediments with a low concentration of nitrogen, phosphorous and copper, while the internal stations contained less sand, more organic matter and higher concentrations of nitrogen, phosphorous and copper and were dominated by gammarids and Corophium sp. (Guerra-García & García-Gómez, 2004). However, the dominance of Siphonoecetes in their samples may have been due to the sediment type rather than pollution. 

Amphipods are considered to be sensitive to a variety of pollutants (Bellan-Santini, 1980; Dauvin, 2018). For example, the ECOTOX database (Olker et al., 2022) recorded the following lethal concentrations in Ampelisca sp.: 24-hour LC₅₀ of 2.5 mg/l cadmium (Cd); 96-hour LC₅₀ of between 0.2 and 1.32 mg/l Cd; 10-day LC₅₀ of 36 µg/l Cd; 96-hour LC₅₀ between 4.16 and 8.46 mg/l Arsenic (As); 48-hour LC₅₀ of ca 56 µg/l chromium (Cr); 96-hour LC₅₀ of ca 33.5 µg/l Copper (Cu), 7-day LC₅₀ of 90 µg/l Cu and 10-day LC₅₀ of 20.5 µg/l Cu; 96-hour LC₅₀ of 0.62 mg/l Lead (Pb) and 10-day LC₅₀ of ca 3 mg/l Pb; 10-day LC₅₀ of ca 2.4 mg/l Nickel (Ni) and a 10-day LC₅₀ of ca 0.34 mg/l Zinc (Zn), depending on the study. 

In laboratory investigations, Hong & Reish (1987) observed 96-hour LC₅₀ water column concentrations of between 0.19 and 1.83 mg/l of Cd for several species of amphipod. Corophium volutator is highly intolerant of metal pollution at levels often found in estuaries from industrial outfalls and contaminated sewage. A concentration of 38 mg Cu/l was needed to kill 50% of Corophium volutator in 96-hour exposures (Bat et al., 1998). Other metals are far more toxic to Corophium volutator, e.g. Zn was toxic over 1 mg/l and toxicity to metals increases with increasing temperature and salinity (Bryant et al., 1985b). Mortality of 50% was caused by 14 mg/l (Bat et al., 1998). Although exposure to zinc may not be lethal, it may affect the perpetuation of a population by reducing growth and reproductive fitness. Mercury was found to be very toxic to Corophium volutator, e.g. concentrations as low as 0.1 mg/l caused 50% mortality in 12 days. Other metals are known to be toxic include cadmium, which causes 50% mortality at 12 mg/l (Bat et al., 1998); and arsenic, nickel and chromium which are all toxic over 2 mg/l (Bryant et al., 1984; Bryant et al., 1985; 1985b).

Vogt et al. (2018) reviewed the effects of tributyl tin (TBT) on Crustacea. TBT was reported to interfere with carbohydrate and lipid metabolism, growth, sexual maturity, steroid synthesis and reproduction in Crustacea.  In Corophium sp., a 10-day LC₅₀ of ca 329 ng/l TBT chloride was reported while the LOEC (Lowest Observable Effect Concentration) was between 524 and 558 ng/l TBT chloride (ECOTOX; Olker et al., 2022). 

Sensitivity assessment. The above evidence suggests that organotins may affect reproduction and hence population dynamics in amphipods because they are crustaceans and could provide lethal at high enough concentrations. Similarly, the evidence reports that exposure to heavy metals under laboratory conditions can result in significant mortality in amphipods, depending on the duration and concentration of exposure.  Therefore, resistance is assessed as 'Low'. Their recolonization of affected areas will require the polluting heavy metals to be removed or reduced in concentration. Hence, resilience is assessed as 'Medium' and sensitivity as 'Medium'. However, confidence in the assessment is 'Low' due to the lack of direct evidence on the characteristic species. 

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

Amphipods in general and ampeliscid amphipods, in particular, seem particularly sensitive to contamination with oil (Suchanek, 1993).  Dauvin (2018) noted that several studies have shown the great sensitivity of the amphipods to hydrocarbons compared to other groups of invertebrates, either in the laboratory or due to environmental to pollution by hydrocarbons. For example, Dauvin (2018) noted that oil spills in the Baltic Sea (Palva, Tsesis and Antonio Gramsci), in the South Atlantic (the Esso Essen), the western part of the English Channel (the Amoco Cadiz) (Dauvin, 1987, 1998), in Galicia, Spain  (the Aegean Sea) (Gomez Gesteira and Dauvin, 2000), and in Milford Haven, Wales, UK  (the Sea Empress) (Nikitik & Robinson, 2003), demonstrated the high sensitivity of amphipods to accidental oil spill pollution.  Both the Amoco Cadiz and the Aegean Sea oil spills resulted in the disappearance of amphipods from polluted stations (Dauvin, 2018). Southward (1982) suggested it took five or more years for amphipod abundance to return after oil spills, presumably due to the persistence of oil in the sediments (Southward, 1982; Suchanek, 1993). Nikitik & Robinson (2003) reported a sharp decline in amphipods (Ampelisca sp. and Harpinia sp.) in Milford Haven after the Sea Empress spill but noted that amphipod populations showed signs of recovery within five years. 

Furthermore, light fractions (C10 - C19) of oils are much more toxic to Corophium volutator than heavier fractions (C19 - C40). In exposures of up to 14 days, light fraction concentrations of 0.1 g/kg sediment caused high mortality. It took 9 g/kg sediment to achieve similar mortalities with the heavy fraction (Brils et al., 2002). Roddie et al. (1994) found high levels of mortality of Corophium at sites contaminated with crude oil.

Sensitivity assessment.  There is considerable evidence that amphipods, as a group, are highly sensitive to the effects of hydrocarbon contamination. Therefore, resistance is assessed as 'None'. Recolonization is dependent on a reduction of the hydrocarbon concentration in the sediment (presumably by degradation or dilution) and resilience is assessed as 'Medium'. Hence, sensitivity is assessed as 'Medium'. 

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

Hua & Reylea (2014) examined the effects of multiple insecticides on the amphipod Crangonyx psesudocracilis and isopod Asellus aquaticus in mesocosms. The exposed mesocosms to organophosphates (chlorpyrifos, diazinon, endosulfan, and malathion) at 10ug/l (low concentration) or 40 ug/l (high concentration) individually or in mixtures for up to 18 weeks. They found that the low concentration of diazinon, endosulfan, and malathion had no effect on the amphipods but the low concentration of chlorpyrifos eliminated them. Amphipod abundance was severely reduced by malathion at the high concentration but eliminated by chlorpyrifos, diazinon, and endosulfan (Hua & Reylea, 2014).

LeBlanc (2007) reviewed crustacean endocrine toxicology and list several synthetic compounds that had been demonstrated to have anti-ecdysteroidal effects (EC₅₀), and hence interfere with embryo development, growth (moulting) and reproduction. These included Bisphenol A, Diethylphthalate, 4-Nonylphenol, Fluoranthene, Lindane, 4,4-DDD, 2,4-DDE, 4,4-DDE, 4,4-DDT, Dieldrin, Reseratrol, and Zearalenone (LeBlanc, 2007). 

Corophium volutator is paralysed by pyrethrum-based insecticide sprayed onto the surface of the mud (Gerdol & Hughes, 1993) and pyrethrum would probably cause significant mortalities if it found its way into estuaries from agricultural runoff. Nonylphenol is an anthropogenic pollutant that regularly occurs in water bodies, it is an oestrogen mimic that is produced during the sewage treatment of non-ionic surfactants and can affect Corophium volutator (Brown et al., 1999). Nonylphenol is a hydrophobic molecule and often becomes attached to sediment in water bodies. This will make nonylphenol available for ingestion by Corophium volutator in estuaries where much of the riverine water-borne sediment flocculates and precipitates out of suspension to form mudflats. Nonylphenol was not lethal to Corophium volutator but does reduce growth and has the effect of causing the secondary antennae of males to become enlarged, which can make the amphipods more vulnerable to predators (Brown et al., 1999).  However, The ECOTOX database (Olker et al., 2022) recorded a 96-hour LC50 of ca 1.67 mg/l and a 10-day LC50 of ca 0.62 mg/l for 4-nonylphenol in Corophium sp.. Corophium volutator is killed by 1% ethanol if exposed for 24 hours or more but can withstand higher concentrations in short pulses. Such short pulses, however, have the effect of rephasing the diel rhythm and will delay the timing of swimming activity for the duration of the ethanol pulse (Harris & Morgan, 1984b). The ECOTOX database records LC50s for a range of synthetic compounds, for example, fluoranthene, Pentachlorophenol, trichlorobenzene, Sodium methylundecyl benzenesulfonate (a pesticide), and the synthetic pyrethroid (4-Chloro-alpha-(1-methylethyl)benzeneacetic acid cyano(3-phenoxyphenyl)methyl ester). 

Sensitivity assessment.  The above evidence suggests that amphipods are likely to be affected adversely by a range of synthetic compounds, especially insecticides, depending on exposure duration and concentration.  Therefore, resistance is assessed as 'Low', resilience as 'High', and sensitivity as 'Low'.

Radionuclide contamination

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

Evidence

Corophium volutator was reported to readily absorb radionuclides such as americium and plutonium from water and contaminated sediments (Miramand et al., 1982). However, the effect of contamination on the individuals was not known but accumulation through the food chain was assumed (Miramand et al., 1982). There was 'No evidence' on which to base an assessment.

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 relevant evidence was found.

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

Vaquer-Sunyer & Duarte (2008) suggested that crustaceans (as a group) were the most sensitive to deoxygenation after fish, and more sensitive than polychaetes, echinoderms and molluscs. Amphipods appear not to be tolerant of reduced oxygenation. For example, Ampelisca agassizi was reported to be sensitive to hypoxia (Diaz & Rosenberg, 1995). Jassa falcata, another tube-building amphipod species, was absent from Californian harbours with low oxygen concentrations (0-2.5 mg/l) but recovery was rapid with recolonization taking place within 6-9 months (Barnard, 1958).

In a series of experiments Gamenick et al. (1996) suggested that Corophium volutator was highly sensitive to hypoxia and suffered 50% mortality after just 4 hours in hypoxic conditions (0.032 mg/l), or in 2 hours if there was a rapid build-up of sulphide (Gamenick et al., 1996; Gray et al., 2002). Corophium volutator was the most sensitive to hypoxia when compared to other species tested, e.g. polychaetes.  Also, in areas where the sediment was covered to induce anoxia and sulphide build-up, Corophium volutator was the last of the species examined to recolonize the sediment; after two months (Gamenick et al., 1996). These results are largely in concordance with other work by Gamble (1970) who found that survival rates were temperature dependent with individuals surviving longer at lower temperatures. Gamble (1970) found that at 5°C most individuals were inactive after 30 minutes of exposure to anaerobic seawater and that mortality occurred later, the inactivity may have allowed the species to survive longer (Gamble, 1070). At 10°C, Corophium volutator survived for 22 hours while Corophium arenarium survived for 25 hours. Gray et al. (2002) also reported that Gammarus oceanicus and other crustacea survived for less than 100 hours at <0.15 ml O₂/l (<0.21 mg O₂/l at 10°C, 17 psu) (Dries & Theede, 1974; cited in Gray et al., 2002). 

Sensitivity assessment. No evidence of the effects of deoxygenation of the characteristic species Siphonoecetes was found. However, the evidence above suggests that amphipods are sensitive to hypoxia. Therefore, resistance is assessed as 'Low', resilience as 'High' and sensitivity as 'Low' but with 'Low' confidence due to the lack of direct evidence on Siphonoecetes spp. 

Nutrient enrichment

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

Evidence

Guerra-García & García-Gómez (2004) compared amphipod communities inside the harbour of Ceuta, North Africa, with communities outside the harbour. Siphonoecetes dellavallei dominated the amphipod community outside the harbour in sandy sediments with a low concentration of nitrogen, phosphorous and copper, while the internal stations contained less sand, more organic matter and higher concentrations of nitrogen, phosphorous and copper and were dominated by gammarids and Corophium sp. (Guerra-García & García-Gómez, 2004). However, the dominance of Siphonoecetes in their samples may have been due to the sediment type rather than pollution. 

Bigot et al. (2006) examined amphipod communities in the vicinity of the power station and sugar cane plant effluents in Reunion Island (Indian Ocean). The sugar mill effluent discharged ca 0.8-1.1 tonnes of particular matter per day, and 0.023 mg/l of total organic matter, and the thermal effluent included 0.33-0.98 tons of particulate matter and 0.021 mg/l total organic matter. Siphonoecetes sp. was one of the dominant crustaceans in the community closest to the outfalls, and contributed to the annual variation in species abundance. However, they concluded that its variation in abundance was probably due to natural population fluctuations rather than organic enrichment. 

De-la-Ossa-Carretero et al. (2012) examined the effect of five different sewage outfalls on amphipod communities on the Castellon coast (NE Spain). They noted that most of the species showed high sensitivity. In particular, Bathyporeia borgi, Perioculodes longimanus and Autonoe spiniventris, were sensitive while other species such as Ameplisca brevicornis appeared to be more tolerant to the sewage input. They noted that burrowing (fossorial) species were more sensitive, while the tube-dwelling (domicolous) species were less affected. They suggested that tube-dwelling species were less exposed to contaminated interstitial water and could pump water into their burrows to avoid the effects of deoxygenation due to organic enrichment (De-la-Ossa-Carretero et al., 2012). In a similar study of sewage effluents on the Alicante coast, De-la-Ossa-Carretero et al. (2016b) reported the amphipods Gammarella fucicola, Ampelisca spinipes, Siphonoecetes bulborostrum and Pseudolirius kroyeri were abundant in the transect closest to the harbour and sewage discharge. 

Sensitivity assessment. The above evidence suggests that Siphonoecetes spp. are amongst a number of amphipod species that are resistant or organic enrichment and that their tube-dwelling habit may provide protection from the indirect effects of organic or nutrient enrichment. Therefore, resistance is assessed as 'High', although their response may be mediated by changes in the sediment and/or the moderator energy (wave exposure and tidal flow) conditions typical of this biotope.  Hence, resilience is assessed as 'High' and sensitivity as 'Not sensitive', although the evidence does not allow a direct comparison with the benchmark. 

Organic enrichment

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

Evidence

Guerra-García & García-Gómez (2004) compared amphipod communities inside the harbour of Ceuta, North Africa, with communities outside the harbour. Siphonoecetes dellavallei dominated the amphipod community outside the harbour in sandy sediments with a low concentration of nitrogen, phosphorous and copper, while the internal stations contained less sand, more organic matter and higher concentrations of nitrogen, phosphorous and copper and were dominated by gammarids and Corophium sp. (Guerra-García & García-Gómez, 2004). However, the dominance of Siphonoecetes in their samples may have been due to the sediment type rather than pollution. 

Bigot et al. (2006) examined amphipod communities in the vicinity of the power station and sugar cane plant effluents in Reunion Island (Indian Ocean). The sugar mill effluent discharged ca 0.8-1.1 tonnes of particular matter per day, and 0.023 mg/l of total organic matter, and the thermal effluent included 0.33-0.98 tons of particulate matter and 0.021 mg/l total organic matter. Siphonoecetes sp. was one of the dominant crustaceans in the community closest to the outfalls, and contributed to the annual variation in species abundance. However, they concluded that its variation in abundance was probably due to natural population fluctuations rather than organic enrichment. 

De-la-Ossa-Carretero et al. (2012) examined the effect of five different sewage outfalls on amphipod communities on the Castellon coast (NE Spain). They noted that most of the species showed high sensitivity. In particular, Bathyporeia borgi, Perioculodes longimanus and Autonoe spiniventris, were sensitive while other species such as Ameplisca brevicornis appeared to be more tolerant to the sewage input. They noted that burrowing (fossorial) species were more sensitive, while the tube-dwelling (domicolous) species were less affected. They suggested that tube-dwelling species were less exposed to contaminated interstitial water and could pump water into their burrows to avoid the effects of deoxygenation due to organic enrichment (De-la-Ossa-Carretero et al., 2012). In a similar study of sewage effluents on the Alicante coast, De-la-Ossa-Carretero et al. (2016b) reported the amphipods Gammarella fucicola, Ampelisca spinipes, Siphonoecetes bulborostrum and Pseudolirius kroyeri were abundant in the transect closest to the harbour and sewage discharge. 

Sensitivity assessment. The above evidence suggests that Siphonoecetes spp. are amongst a number of amphipod species that are resistant or organic enrichment and that their tube-dwelling habit may provide protection from the indirect effects of organic or nutrient enrichment. Therefore, resistance is assessed as 'High', although their response may be mediated by changes in the sediment and/or the moderator energy (wave exposure and tidal flow) conditions typical of this biotope.   Hence, resilience is assessed as 'High' and sensitivity 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

If sedimentary substrata were replaced with rock substrata the biotope would be lost, as it would no longer be a sedimentary habitat and would no longer support sea pens and burrowing megafauna. Resistance to the pressure is considered ’None‘, and resilience ’Very low‘ or ‘None’ (as the pressure represents a permanent change), and the sensitivity of this biotope is 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

This biotope (SS.SSa.CFiSa.SiphNephVen) is only recorded from moderate tidal steams (0.5-1.5 m/sec) and moderately exposed wave conditions. Siphonoecetes spp. are recorded from medium and coarse sandy bottoms (Myers & McGrath, 1979; Mora, 1991; Moreira et al., 2008; De-la-Ossa-Carretero et al., 2015), predominately sand with little mud on the Dogger Bank (Reiss & Kröncke, 2005) and fine sands (Bigot et al., 2006). Therefore, the biotope and the dominant characteristic species are dependent on the presence of fine to coarse sands. A change in sediment type from sand to 'mud and sandy muds' or to mixed or coarse sediments would probably result in the loss of the biotope and its reclassification due to the difference in sediment type and the resultant change in the associated community. Hence, resistance is assessed as 'None', resilience as 'Very low' (permanent change) and sensitivity as 'High'.  

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

Siphonoecetes spp. live in burrows made of agglutinated sand grains and shells in the sediment. The species are small (< 1cm in length) so we can presume that their burrows are fairly shallow (i.e. only a few centimetres deep).  Hence, the removal of the sediment to a depth of 30 cm in the affected area (the benchmark) would remove the entire population within the affected area. Therefore, resistance is assessed as 'None'. Once the sediment returns to its prior state, resilience is probably 'Medium' so 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

No evidence of the effects of physical abrasion of the sediment surface or penetration or disturbance of the subsurface in a Siphonoecetes-dominated habitat was found.  However, evidence from other similar amphipod-dominated habitats may be a useful proxy.  For example, sediment turnover caused by cockles and lugworms disturbed the burrows of Corophium volutator and caused a significant negative effect on Corophium volutator density as a result of the increased rate of swimming making the amphipod more vulnerable to predation (Flach & De Bruin, 1993, 1994).  Corophium arenarium was also sensitive to sediment disturbance from bioturbating species (Flach, 1993). In the Columbia river, no significant difference was found in Corophium volutator densities before and after dredging a channel and no difference between the dredged site and a control site (McCabe et al., 1998). Presumably, the dredging did cause mortality of Corophium volutator but recolonization was so rapid that no difference was found. The extraction of cockles by sediment raking and mechanical disturbance and digging for lugworms for bait is likely to cause significant mortality of Corophium volutator. Bait digging was found to reduce Corophium volutator densities by 39%.  Juveniles were most affected, suffering a 55% reduction in dug areas (Shepherd & Boates, 1999). 

Sensitivity assessment. Siphonoecetes spp. are probably adapted to minor hydrodynamic disturbance of the surface of the sediment. However, abrasion by passing fishing gear may disturb the surface of the sediment and either destroy the surface of their tubes or cause them to leave their tubes, increasing their susceptibility to predation. The species is very small and unlikely to be removed in significant numbers. Therefore, abrasion may cause some mortality to the resident population and resistance is assessed as 'Medium'. However, recovery is likely to be rapid and so resilience is assessed as 'High' and sensitivity as 'Low' albeit with 'Low confidence due to the lack of direct evidence. 

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

No evidence of the effects of physical abrasion of the sediment surface or penetration or disturbance of the subsurface in a Siphonoecetes-dominated habitat was found.  However, evidence from other similar amphipod-dominated habitats may be a useful proxy.  For example, sediment turnover caused by cockles and lugworms disturbed the burrows of Corophium volutator and caused a significant negative effect on Corophium volutator density as a result of the increased rate of swimming making the amphipod more vulnerable to predation (Flach & De Bruin, 1993, 1994).  Corophium arenarium was also sensitive to sediment disturbance from bioturbating species (Flach, 1993). In the Columbia river, no significant difference was found in Corophium volutator densities before and after dredging a channel and no difference between the dredged site and a control site (McCabe et al., 1998). Presumably, the dredging did cause mortality of Corophium volutator but recolonization was so rapid that no difference was found. The extraction of cockles by sediment raking and mechanical disturbance and digging for lugworms for bait is likely to cause significant mortality of Corophium volutator. Bait digging was found to reduce Corophium volutator densities by 39%.  Juveniles were most affected, suffering a 55% reduction in dug areas (Shepherd & Boates, 1999). 

Sensitivity assessment. Siphonoecetes spp. are probably adapted to minor hydrodynamic disturbance of the surface of the sediment. However, penetration and disturbance of the sediment by passing fishing gear may destroy their tubes and remove them from the sediment increasing their susceptibility to predation. The species is very small and unlikely to be removed in significant numbers. Therefore, penetration may cause some or significant mortality to the resident population and resistance is assessed as 'Low'. However, recovery is likely to be rapid and so resilience is assessed as 'High' and sensitivity as 'Low' albeit with 'Low confidence due to the lack of direct evidence. 

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

Changes in light penetration or attenuation associated with this pressure are not relevant in this circalittoral biotope. The characteristic species are infaunal so unlikely to be directly dependent on light. In addition, the biotope occurs in moderate tidal flow and moderate wave exposure which suggests that the sand-dominated habitat is probably well-sorted and subject to occasional resuspension, especially during winter storms.  Siphonoecetes spp. is a surface deposit feeder that feeds on non-surface bound organic matter, including microflora and microfauna, but without ingesting sediment particles (Guidi, 1986; Guerra-García et al., 2014). Therefore, an increase in turbidity may reduce the development of microflora on the sediment surface but it can probably ingest other food sources.  The greatest risk is a change in sediment type due to an increase in fine sediment in suspension (see above) although the hydrographic conditions should prevent the accumulation of fine sediments.  Therefore, resistance is assessed as 'High', resilience as 'High', and sensitivity as 'Not sensitive'. 

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

Siphonoecetes spp. live in burrows made of agglutinated sand grains and shells in the sediment. The species are small (< 1cm in length) so we can presume that their burrows are fairly shallow (i.e. only a few centimetres deep).  Siphonoecetes spp. are recorded from medium and coarse sandy bottoms (Myers & McGrath, 1979; Mora, 1991; Moreira et al., 2008; De-la-Ossa-Carretero et al., 2015), predominately sand with little mud on the Dogger Bank (Reiss & Kröncke, 2005) and fine sands (Bigot et al., 2006). Therefore, the biotope and the dominant characteristic species are dependent on the presence of fine to coarse sands. The sudden deposition of 5 cm of fine sediment may be detrimental for species that are adapted to living and burrowing in fine to coarse sediment. However, the hydrographic regime would probably remove the deposited sediment with a few tidal cycles.  Therefore, resistance is assessed as 'High', resilience as 'High', and 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

Siphonoecetes spp. live in burrows made of agglutinated sand grains and shells in the sediment. The species are small (< 1cm in length) so we can presume that their burrows are fairly shallow (i.e. only a few centimetres deep).  Siphonoecetes spp. are recorded from medium and coarse sandy bottoms (Myers & McGrath, 1979; Mora, 1991; Moreira et al., 2008; De-la-Ossa-Carretero et al., 2015), predominately sand with little mud on the Dogger Bank (Reiss & Kröncke, 2005) and fine sands (Bigot et al., 2006). Therefore, the biotope and the dominant characteristic species are dependent on the presence of fine to coarse sands.

The sudden deposition of 30 cm of fine sediment may be detrimental for species that are adapted to living and burrowing in fine to coarse sediment. They may struggle to burrow up through the deposited sediment and be suffocated within the affected area. The hydrographic regime would probably remove the deposited sediment over a period of time dependent on the exact location.  Therefore, resistance is assessed as 'Low', resilience as 'High', and sensitivity as 'Low', albeit with 'Low' confidence due to the lack of direct evidence. 

Litter

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

Evidence

This pressure is '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

Siphonoecetes spp. and other infauna are probably sensitive to localised vibration caused by the approach of predators but are unlikely to respond to noise as defined under this pressure. Therefore, the pressure is assessed as 'Not relevant'. 

Introduction of light or shading

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

Evidence

Changes in light penetration or attenuation associated with this pressure are probably not relevant in this circalittoral biotope. The characteristic species are infaunal so unlikely to be directly dependent on light. In addition, the biotope occurs in moderate tidal flow and moderate wave exposure which suggests that the sand-dominated habitat is probably well-sorted and subject to occasional resuspension, especially during winter storms.  Siphonoecetes spp. is a surface deposit feeder that feeds on non-surface bound organic matter, including microflora and microfauna, but without ingesting sediment particles (Guidi, 1986; Guerra-García et al., 2014). Therefore, shading might reduce the development of microflora on the sediment surface but it can probably ingest other food sources. Therefore, resistance is assessed as 'High', resilience as 'High', and sensitivity as 'Not sensitive'. 

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

As the amphipods that characterize this biotope have benthic dispersal strategies (via brooding), water transport is not a key method of dispersal over wide distances, as it is for some marine invertebrates that produce pelagic larvae. Where populations were removed changes in water transport of adults may, however, be reduced by changes in local hydrodynamics preventing recolonization. Conversely, a barrier may enhance local connectivity by reducing the loss of adults from the system. Therefore, resistance is assessed as ‘High’, resilience ‘High’ (by default) and the biotope is assessed as ‘Not sensitive’.

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

Siphonoecetes spp. and other infauna are probably sensitive to localised shading caused by the approach of predators but are unlikely to respond to visual disturbance as defined under this pressure. Therefore, the pressure is assessed 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

No information on the translocation or genetic modification of this species 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

No information on the potential interaction of Siphonoecetes spp. and invasive non-native species was found. 

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 the effects of potential diseases or parasites was found. Falck & Bowman (1994) reported that ca 50% of tubes created by Siphonoecetes sp. in the northern Red Sea were also occupied by the commensal harpacticoid copepod Parasunaristes chelicerata.  However, as a commensal, the harpacticoid probably gains benefit from sharing the tube with its host without causing any harm. 

Removal of target species

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

Evidence

Siphonoecetes spp. are not targeted by collectors or fisheries. Therefore, this pressure is 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

Physical disturbance to the sediment is addressed under the 'physical loss' and 'physical disturbance' pressures above. No biological relationship between Siphonoecetes spp. and other species (except its Red Sea commensal) were found in UK waters. It is probably fed on by demersal fish and decapods but as their diet is varied and they are highly mobile its loss is unlikely to be significant. Therefore, bycatch may cause some mortality to the resident population of Siphonoecetes sp. and resistance is assessed as 'Medium'. However, recovery is likely to be rapid and so resilience is assessed as 'High' and sensitivity as 'Low' albeit with 'Low confidence due to the lack of direct evidence.