The Marine Life Information Network

Limited evidence was found on the effect of changes in temperature and resistance is inferred from the characterizing species ranges. 

Hesionura elongata occurs in the Canary Islands and Caribbean, which suggests a resistance of higher water temperatures than around UK and Irish seas (Brito et al., 2005; Miloslavich et al., 2010). Protodorvillea kefersteini is found in the North Atlantic to the  North Sea and English Channel, Mediterranean and Black Sea (Marine Species Identification Portal).

Sensitivity assessment. This assessment relies on limited evidence and utilises global species distribution records and so confidence is low. As all characterizing species occur in water temperatures greater than they are likely to experience in the UK, biotope resistance and resilience are assessed as ‘High’ and the biotope is considered to be ‘Not Sensitive’. There is low confidence associated with this assessment as limited evidence was available.

Limited evidence was returned on the effect of changes in temperature and resistance is inferred from the species range. Hesionura elongata has been identified in samples from water ranging from 7.3-24°C (OBIS, 2016). Protodorvillea kefersteini is found in the North Atlantic to the North Sea and English Channel, Mediterranean and Black Sea (Marine Species Identification Portal).

Sensitivity assessment. Limited evidence was available and this assessment is based on non-peer reviewed literature on species range. A 5°C decrease in temperature for one month period is likely to impact the characterizing species in winter months and therefore resistance is ‘Medium’, resilience is ‘High’ and Sensitivity is ‘Low’. 

The biotope occurs in ‘full’ salinity conditions. An increase in one MNCR salinity category to hypersaline conditions is likely to cause mortality of characterizing species. Resistance is ‘None’, Resilience is ‘High (following restoration of habitat conditions)’ and sensitivity is assessed as ‘High’. This assessment is assessed based on distribution and confidence is low.

This biotope occurs in full salinity habitats. A change at the pressure benchmark is assessed as a decrease from full to reduced salinity(18-30 ppt)

Degraer et al. (2006) report that Hesionura elongata was found in greatest abundance outside the near coastal zone (in samples from across the Belgium part of the North Sea). This suggests that the species is likely to occur in greater abundance in habitats with full salinity compared to variable salinity or reduced. Moulaert et al. (2008) also found that species communities in which Hesionura elongata was an indicator species were only present >16 km from the coast and displayed a positive correlation with increasing salinity.

Sensitivity assessment. Resistance is assessed as ‘Medium’ as Hesionura elongata  may decrease in and other characterizing species may decrease in  abundance. Resilience is assessed as ‘High’ and sensitivity is assessed as ‘Low’.

No information on tidal streams was presented in the biotope description from JNCC (2015). This biotope occurs in clean sands and gravels. Sands are less cohesive than mud sediments and a change in water flow at the pressure benchmark may alter sediment transport patterns within the biotope.  Hjulström (1939), concluded that fine sand (particle diameter of 0.3-0.6 mm) was easiest to erode and required a mean velocity of 0.2 m/s. Erosion and deposition of particles greater than 0.5 mm require a velocity > 0.2 m/s to alter the habitat. The topography of this habitat is shaped by currents and wave action that influence the formation of ripples in the sediment. Specific fauna may be associated with troughs and crests of these bedforms which may form following an increase in water flow, or disappear following a reduction in flow.

Sensitivity assessment. This biotope probably occurs in areas subject to moderately strong water flows that are a key factor maintaining the clean sand habitat. Changes in water flow may alter the topography of the habitat and may cause some shifts in abundance. However, a change at the pressure benchmark (increase or decrease)  is unlikely to affect biotopes that occur in mid-range flows and biotope sensitivity is therefore assessed as ‘High’ and resilience is assessed as ‘High’ so that the biotope is considered to be ‘Not sensitive’.

This biotope does not occur in the intertidal, and consequently an increase in emergence is considered not relevant to this biotope.

As this biotope occurs in infralittoral habitats it is not directly exposed to the action of breaking waves.  Associated polychaete species that burrow are protected within the sediment but bivalves would be exposed to oscillatory water flows at the seabed. They and other associated species may be indirectly affected by changes in water movement where these impact the supply of food or larvae or other processes. No specific evidence was found to assess this pressure. 

Sensitivity assessment. The abundance of characterizing species is likely to be unaffected or increase in areas where fine sediment is removed and coarse sediment is present. However, abundance is likely to decrease in areas where fine sediment is deposited. Under the pressure benchmark levels which consider <5% change, Resistance is assessed as  ‘High’ and resilience as ‘High’ and the biotope is assessed as ‘Not Sensitive’.

This pressure is Not assessed but evidence is presented where available.

This pressure is Not assessed but evidence is presented where available.

Contamination at levels greater than the pressure benchmark may adversely influence the biotope. Suchanek (1993) reviewed the effects of oil spills on marine invertebrates and concluded that, in general, on soft sediment habitats, infaunal polychaetes, bivalves and amphipods were particularly affected. The 1969 West Falmouth Spill of Grade 2 diesel fuel, documented by Sanders (1978), illustrates the effects of hydrocarbons in a sheltered habitat with a soft mud/sand substrata (Suchanek, 1993). The entire benthic fauna was eradicated immediately following the spill and remobilization of oil that continued for a period >1 year after the spill contributed to much greater impact upon the habitat than that caused by the initial spill. Effects are likely to be prolonged as hydrocarbons incorporated within the sediment by bioturbation will remain for a long time, owing to slow degradation under anoxic conditions. Oil covering the surface and within the sediment would prevent oxygen transport to the infauna and promote anoxia as the infauna utilise oxygen during respiration. Although this study investigates impacts on an estuarine biotope the impact on benthic infauna communities is likely to be similar in shallow sandbank biotopes.

This pressure is Not assessed but evidence is presented where available.

Insufficient information was available in relation to characterizing species to assess this pressure. Limited evidence is available on other infauna species. Beasley & Fowler (1976) and Germain et al., (1984) examined the accumulation and transfers of radionuclides in Hediste diversicolor from sediments contaminated with americium and plutonium derived from nuclear weapons testing and the release of liquid effluent from a nuclear processing plant. Both concluded that the uptake of radionuclides by Hediste diversicolor was small. Beasley & Fowler (1976) found that Hediste diversicolor accumulated only 0.05% of the concentration of radionuclides found in the sediment. Both also considered that the predominant contamination pathway for Hediste diversicolor was from the interstitial water.

Sensitivity assessment: There is insufficient information available on the biological effects of radionuclides to comment further upon the intolerance of characterizing species to radionuclide contamination. Assessment is given as ‘No Evidence’.

This pressure is Not assessed.

Some, all be it limited evidence was returned by searches on activated carbon (AC). AC is utilised in some instances to effectively remove organic substances from aquatic and sediment matrices. Lillicrap et al. (2015) demonstrate that AC may have physical effects on benthic dwelling organisms at environmentally relevant concentrations at remediated sites.

Limited evidence was returned on effects of decreased dissolved oxygen concentrations on the characterizing species.

All meiofauna have some sensitivity to extended hypoxia, although more mobile nematode species are able to emigrate into the water column in high numbers where they survive (Wetzel et al., 2013). Emigration is likely to increase predation risk. Although evidence on characterizing species is lacking, densities of meiofauna populations are likely to be lower under prolonged anoxia (Moodley et al., 1997).  

A turbellarian, Macrostomum lignano was found to be a species that is tolerant of a wide range of oxygen concentrations (being able to maintain aerobic metabolism from extremely low P-O2 up to hyperoxic conditions), and is thought to be resistant to the drastic environmental oxygen variations that occur within intertidal sediments (Rivera-Ingraham et al., 2013).

As the biotope occurs in high energy areas strong water flow occurs and deoxygenation is likely to be short lived.

Sensitivity assessment. Due to the limited evidence confidence in this assessment is low. A reduction in meiofauna populations is likely if deoxygenation persisted for long periods, but this is unlikely due to high water flow. As some species are likely to emigrate or maintain aerobic metabolism under low dissolved oxygen conditions, Resistance is assessed as ‘Medium’, Resilience is ‘High’ and Sensitivity is assessed as ‘Low’.

Meiofauna respond to nutrient enrichment. The distribution of different meiofauna assemblages has been identified as a good tool for detecting short-term responses of the benthic domain to nutrient enrichment from sources such as river discharge (Semprucci et al., 2015). In the Bay of Cadiz, Spain, abundance of meiofauna was seven times higher in the presence of macroalgae (Bohorquez et al., 2013).

Sensitivity assessment. As the benchmark levels comply with WFD criteria for good status, Resistance is ‘High’, Resilience is ‘High’ and the biotope is 'Not sensitive' at the benchmark level.

Protodorvillea kefersteini was identified as a ‘progressive’ species, i.e. one that shows increased abundance under slight organic enrichment (Leppakoski, 1975, cited in Gray, 1979; Hiscock et al., 2004). Protodorvillea kefersteini can become very plentiful in organically enriched habitats (Warwick et al., 1986), this species was very abundant in the vicinity of a sewage outfall at Kircaldy (S.C. Hull pers. comm).  Protodorvillea  kefersteini were dominant species in muddy,  organically enriched sediments (organic content approximately 25%) located about 100 and 500 m from fish farm cages, in a bay in Corsica, France (Terlizzi et al., 2010). Similarly, this species was also dominant in sediments close to fish farms in Greek bays where organic matter and nitrogen content had increased.

Sensitivity assessment.  Protodorvillea kefersteini is tolerant of organic enrichment. At the pressure benchmark organic inputs are considered likely to represent a food subsidy and are unlikely to significantly affect the structure of the biological assemblage or impact the physical habitat. Biotope sensitivity is therefore assessed as ‘High’ and resilience as ‘High’ (by default) and the biotope is therefore considered to be ‘Not sensitive’.

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.

This biotope is only found in infralittoral sand banks and sand waves and other areas of mobile medium-coarse sand, and characterizing species  burrow or live interstitially within the sediment and would not be able to survive if the substratum type was changed to either a soft rock or hard artificial type. Consequently, the biotope would be lost altogether if such a change occurred. 

Sensitivity assessment.  The Resistance to this change is ‘None’, and the Resilience is assessed as ‘Very low’, due to the long-term nature of a change in substratum.  The biotope is assessed to have a ‘High’ Sensitivity to this pressure at the benchmark. 

Increase in gravel content within the Folk classes is unlikely to negatively impact the characterizing species Hesionura elongata. Increases in finer sand or silt are likely to reduce abundance of Hesionura elongata  as this species is found in greater abundance in sediments with larger grain sizes, and decreases in abundance in fine sediments. Moulaert & Hostens (2007) found that higher gravel content and sediment grain size was a key environmental factor determining the presence of Hesionura elongata. Desprez (2000) found that a change of habitat to fine sands from coarse sands and gravels (from  deposition of screened sand following aggregate extraction) changed the biological communities present. Tellina pygmaea and dominated the fine sand community.

Sensitivity assessment.  Sediment changes are likely to alter the composition of the biological assemblage leading to biotope reclassification. Biotope resistance is, therefore, assessed as Low (as some species may remain), resilience is Very low (the pressure is a permanent change) and sensitivity is assessed as High.

A number of studies assess the impacts of aggregate extraction on sand and gravel habitats. Extraction would remove the infauna that may be present in this biotope. Recovery of sediments will be site-specific and will be influenced by currents, wave action and sediment availability (Desprez, 2000). Except in areas of mobile sands, the process tends to be slow (Kenny & Rees, 1996; Desprez, 2000 and references therein).  Boyd et al., (2005) found that in a site subject to long-term extraction (25 years), extraction scars were still visible after six years and sediment characteristics were still altered in comparison with reference areas with ongoing effects on the biota. The strongest currents are unable to transport gravel. A further implication of the formation of these depressions is a local drop in current strength associated with the increased water depth, resulting in deposition of finer sediments than those of the surrounding substrate (Desprez et al., 2000 and references therein). See the physical change pressure for assessment

Sensitivity assessment. Resistance is assessed as ‘None’ as extraction of the sediment swill remove the characterizing and associated species present. Resilience is assessed as ‘Medium’ as some species may require longer than two years to re-establish (see resilience section) and sediments may need to recover (where exposed layers are different). Biotope sensitivity is therefore assessed as ‘Medium’.

No evidence. The characterizing species are infaunal and likely to be protected from abrasion, although movement of sediments may damage a proportion of the population. Biotope resistance is assessed as 'Medium' and resilience as 'High', so that biotope sensitivity is considered to be 'Low'.

Protodorvillea kefersteini is soft-bodied and therefore vulnerable to damage by physical abrasion. However, its environmental position as burrowing interstitial species should provide a high degree of protection from activities that lead to surface abrasion only. Similarly, as a small polychaete species, living  infaunally  and capable of burrowing rapidly, Hesionura elongata is also  likely to withstand physical disturbance caused by bottom towed fishing gears (such as otter or beam trawls) (Vanosmael et al., 1982; Bolam et al., 2014).  Experiments in shallow, wave disturbed areas, using a toothed, clam dredge, found that some polychaete taxa without external protection and with a carnivorous feeding mode were enhanced by fishing. Protodorvillea kefersteini was one of these: large increases in abundance in samples were detected post dredging and persisting over 90 days. The passage of the dredge across the sediment floor will have killed or injured some organisms that will then be exposed to potential predators/scavengers (Frid et al., 2000; Veale et al., 2000) providing a food source to mobile scavengers including these species. 

 In a coarse gravelly substratum exposed to high current velocities the crab Cancer pagurus was observed to dig pits, approximately 30 cm in diameter and 10 cm deep. Experiments were conducted to identify macrobenthic recolonization processes and differences in abundance between pits and unmanipulated areas.Protodorvillia kefersteini (McIntosh) (Polychaeta) showed a rapid increase in abundance at 21 days after disturbance (Thrush, 1986).

Gilkinson et al. (1998) simulated the physical interaction of otter trawl doors with the seabed in a laboratory test tank using a full-scale otter trawl door model.  Between 58% and 70% of the bivalves in the scour path that were originally buried were completely or partially exposed at the test bed surface.  However, only two out of a total of 42 specimens showed major damage.  The pressure wave associated with the otter door pushes small bivalves out of the way without damaging them.  Where species can rapidly burrow and reposition (typically within species occurring in unstable habitats) before predation mortality rates will be relatively low. These experimental observations are supported by diver observations of fauna dislodged by a hydraulic dredge used to catch Ensis spp. Small bivalves were found in the trawl tracks that had been dislodged, from the sediments, including the venerid bivalves Dosinia exoleta, Chamelea striatula and the hatchet shell Lucinoma borealis.  These were usually intact (Hauton et al., 2003) and could potentially reburrow. Tellina (formerly Moerella pygmaea) may, therefore, be displaced by penetration and disturbance but survive. 

Sensitivity assessment. Evidence is limited but the biological assemblage present in this biotope is characterized by species that are likely to be relatively tolerant of penetration and disturbance of the sediments. Either species are robust or buried within sediments or are adapted to habitats with frequent disturbance (natural or anthropogenic) and recover quickly. Biotope resistance is assessed as ‘Medium’ as some species will be displaced and may be predated or injured and killed. Biotope resilience is assessed as ‘High’ as most species will recover rapidly. Biotope sensitivity is therefore assessed as ‘Low’.

No direct evidence was found to assess this pressure, the characterizing polychaetes live infaunally and are predatory and may not be directly impacted by either a decrease or increase in suspended solids.

Sensitivity assessment. Based on the characterizing polychaetes biotope resistance is assessed as 'High' and resilience as 'High' so that the biotope is assessed as 'Not sensitive'.

No evidence.

No evidence.

No evidence was returned on the impact of litter on characterizing species for this biotope, although studies show impacts from ingestion of micro plastics by sub surface deposit feeding worms (Arenicola marina) and toxicants present in cigarette butts have been shown to impact the burrowing times and cause DNA damage in ragworms Hediste diversicolor.

Litter, in the form of cigarette butts has been shown to have an impact on Ragworms. Hediste diversicolor showed increased burrowing times, 30% weight loss and a  >2 fold increase in DNA damage when exposed to water with toxicants (present in cigarette butts) in quantities 60 fold lower than reported from urban run-off (Wright et al., 2015). Studies are limited on impacts of litter on infauna and this UK study suggests health of infauna populations are negatively impacted by this pressure.

Studies of sediment dwelling, sub surface deposit feeding worms, a trait shared by species abundant in this biotope, showed negative impacts from ingestion of micro plastics. For instance, Arenicola marina ingests micro plastics that are present within the sediment it feeds within. Wright et al. (2013) carried out a lab study that displayed presence of micro plastics (5% UPVC) significantly reduced feeding activity when compared to concentrations of 1% UPVC and controls. As a result, Arenicola marina showed significantly decreased energy reserves (by 50%), took longer to digest food, and decreased bioturbation levels. These effects would be likely to impact colonisation of sediment by other species, reducing diversity in the biotopes the species occurs within. Wright et al. (2013) also present a case study based on their results, that in the intertidal regions of the Wadden Sea, where Arenicola marina is an important ecosystem engineer, Arenicola marina could ingest 33mᵌ; of micro plastics a year.

Sensitivity assessment. ‘No evidence’ was returned to complete a sensitivity assessment, however, both microplastics and the toxicants present in cigarette butts are likely to have negative impacts on the characterizing species.

No evidence was found on effects of electric and magnetic fields on the characterizing species.

Electric and magnetic fields generated by sources such as marine renewable energy device/array cables may alter behaviour of predators and affect infauna populations. Evidence is limited and occurs for electric and magnetic fields below the benchmark levels, confidence in evidence of these effects is very low.

Field measurements of electric fields at North Hoyle wind farm, North Wales recorded 110µ V/m (Gill et al., 2009). Modelled results of magnetic fields from typical subsea electrical cables, such as those used in the renewable energy industry produced magnetic fields of between 7.85 and 20 µT (Gill et al., 2009; Normandeau et al., 2012). Electric and magnetic fields smaller than those recorded by in field measurements or modelled results were shown to create increased movement in thornback ray Raja clavata and attraction to the source in catshark Scyliorhinus canicular (Gill et al., 2009).

Flatfish species which are predators of many polychaete species including dab Limanda limanda and sole Solea solea have been shown to decrease in abundance in a wind farm array or remain at distance from wind farm towers (Vandendriessche et al., 2015; Winter et al., 2010). However, larger plaice increased in abundance (Vandendriessche et al., 2015). There have been no direct causal links identified to explain these results.

Sensitivity assessment. ‘No evidence’ was available to complete a sensitivity assessment, however, responses by flatfish and elasmobranchs suggest changes in predator behaviour are possible. There is currently no evidence but effects may occur on predator prey dynamics as further marine renewable energy devices are deployed, these are likely to be over small spatial scales and not impact the biotope.

Species within the biotope can probably detect vibrations caused by noise and in response may retreat in to the sediment for protection. However, at the benchmark level the community is unlikely to be sensitive to noise and therefore is ‘Not sensitive’.

All characterizing species live in the sediment and do not rely on light levels directly to feed or find prey so limited direct impact is expected.  Most species will respond to the shading caused by the approach of a predator, however, their visual acuity is probably very low. Even then, additional disturbance, such as an electronic flash, caused the retraction of palps and cirri and cessation of all activity for some minutes. Visual disturbance, in the form of direct illumination during the species' active period at night, may therefore result in loss of feeding opportunities, which may compromise growth and reproduction.

As this biotope is not characterized by the presence of primary producers it is not considered that shading would alter the character of the habitat directly. More general changes to the productivity of the biotope may, however, occur. Beneath shading structures there may be changes in microphytobenthos abundance, which would affect food resources (Tait & Dipper, 1998).

Shading will prevent photosynthesis leading to death or migration of sediment microalgae altering sediment cohesion and food supply to higher trophic levels. The impact of these indirect effects is difficult to quantify.

Sensitivity assessment. Based on the direct impact, biotope Resistance is assessed as ‘High’ and Resilience is assessed as ‘High’ (by default). The biotope Sensitivity is considered to be ‘Not sensitive’.

This biotope is reported in offshore waters (JNCC, 2015) and this pressure is considered 'Not relevant'.

‘Not relevant’ to seabed habitats. NB. Collision by interaction with bottom towed fishing gears and moorings are addressed under ‘surface abrasion’.

Characterizing species may have some, limited, visual perception. As they live in the sediment the species will most probably not be impacted at the pressure benchmark.

Characterizing species are not cultivated or translocated. This pressure is 'Not relevant'.

No evidence.

No evidence.

No characterizing species are targeted directly by fishing activities at a commercial or recreational scale, this pressure is therefore ‘Not relevant’.

Species within the biotope are not functionally dependent on each other, although biological interactions will play a role in structuring the biological assemblage through predation and competition. Removal of species would also reduce the ecological services provided by these species such as secondary production and nutrient cycling.

Sensitivity assessment. Species within the biotope are relatively sedentary or slow moving although the infaunal position may protect some burrowing species from removal. Biotope resistance is, therefore, assessed as ‘Low’ and resilience as ‘High’ as the habitat is likely to be directly affected by removal and some species will recolonize rapidly.  Therefore, sensitvity is assessed as 'Low'. Some variability in species recruitment, abundance and composition is natural and therefore a return to a recognisable biotope should occur within 2 years. Repeated chronic removal would, however, impact recovery.