Eurydice pulchra in littoral mobile sand

12-11-2004
Researched byGeorgina Budd Refereed byDr John Fish
EUNIS CodeA2.2232 EUNIS NameEurydice pulchra in littoral mobile sand

Summary

UK and Ireland classification

EUNIS 2008A2.2232Eurydice pulchra in littoral mobile sand
EUNIS 2006A2.2232Eurydice pulchra in littoral mobile sand
JNCC 2004LS.LSa.MoSa.AmSco.EurEurydice pulchra in littoral mobile sand
1997 Biotope

Description

Well-draining beaches of coarse to medium grained mobile sand, generally on exposed coasts, support populations of burrowing amphipods and the isopod Eurydice pulchra. The degree of drainage appears to be a critical factor in determining the presence of polychaetes; only Scolelepis squamata appears to be capable of tolerating the well-drained sediments of this biotope. In more exposed conditions this biotope may extend the full width of the shore or be restricted to the lower part of the shore with barren sands (LGS.BarSnd) higher up. This biotope has two facies; drying upper and mid shore sands, and highly mobile lower shore and shallow sublittoral sand bars. Burrowing amphipods found frequently include Bathyporeia pelagica, Bathyporeia pilosa, Pontocrates arenarius and Haustorius arenarius. Scolelepis squamata, if present, occurs in only low densities. Oligochaetes may be present and are often common where there is freshwater influence. This community is distinguished from the amphipod-polychaete communities (LGS.AP) by its impoverished polychaete fauna (only occasional Scolelepis squamata or other polychaetes) and its lack of bivalves. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Recorded distribution in Britain and Ireland

A common biotope that occurs on all coasts of Britain and Ireland, where the hydrodynamic regime and underlying topography and geology allow accumulation of sandy substrata. Largely absent in the south-east of England.

Depth range

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Additional information

Other biotopes are represented by this key information review; LGS.AP, LGS.AP.P, LGS.AP.Pon, which are distinguished from LGS.AEur by their greater diversity of polychaete species and the presence of bivalves. The two sub-types; LGS.AP.P and LGS.AP.Pon differ in their proportion of amphipods and polychaetes and the specific species present in the sand.

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Habitat review

Ecology

Ecological and functional relationships

Patterns of distribution and abundance in exposed sandy beaches have been assumed to be primarily controlled by specific species responses to the hydrodynamic climate and sediment characteristics which are intimately linked, a scenario where biological interactions do not appear to play a critical role (McLachlan, 1983). There is a conspicuous lack of information concerning the effects of biotic factors e.g. competition, on the structure and distribution of sandy beach populations, as it is likely that detection of intra- and interspecific competition in such a dynamic environment is very complex (Branch, 1984). Consequently the ecology of exposed sandy beaches remains relatively poorly understood in comparison to rocky shores (Schoeman et al., 2000).
  • The macrofauna of sandy beaches and the meiofauna (and microfauna) of the interstices between sand grains, comprise two entirely separate faunal components with limited overlap or exchanges of energy (McLachlan, 1983). This is because the meiofauna are extremely small interstitial forms while the macrofauna are several orders of magnitude larger.
  • The meiofauna are likely to be important consumers of the microphytobenthic productivity. The dominant components of sandy beach meiofauna are nematodes and harpacticoid copepods with several other taxa of variable importance (McLachlan, 1983). There is a well established relationship between the relative proportions of nematodes and harpaticoids and grain size. Nematodes tend to dominate in finer sediments, harpaticoids in coarser sediments and in sediments with a median grain size of 0.3-0.35 mm they are both equally important (Gray, 1971; McLachlan et al., 1981).
  • The macrofauna of sandy beaches are often abundant. A common feature is the high degree of mobility displayed by all species with shifting distributions in the intertidal. The crustaceans, polychaetes and molluscs are the most conspicuous taxa on sandy beaches, the Crustacea e.g. Eurydice pulchraand Bathyporeia pelagica being most abundant on exposed sandy shores.
  • The sandy beach comprises an unusual ecosystem in that the customary food chain of plants-herbivores-carnivores is not clearly discernible (Eltringham, 1971). The absence of macroalgae means that herbivorous macrofauna either feed on the biogenic film, on and in the deposit, or on phytoplankton from the overlying seawater during high tide, or on plant debris carried by currents to the area from elsewhere.
  • The isopod Eurydice pulchra is a carnivore feeding on a wide range of invertebrates found on sandy shores.
  • The sandy intertidal zone is utilized by juvenile flatfish as a feeding ground. Sole, Solea solea, dab, Limanda limanda, flounder, Platichythys flesus and plaice, Pleuronectes platessa migrate inshore on the flood tide to feed upon tidally active crustaceans, such as Bathyporeia and Eurydice spp., polychaetes and young bivalves and their siphons (Elliott et al., 1998).
  • The biotope complexes represented by this key information review are used by important wintering and passage birds for feeding and roosting and consequently are important visiting predators. Particularly dependent species are brent geese, shelduck, pintail, oystercatcher, ringed and grey plovers, bar-tailed and black-tailed godwits, curlew, redshank, knot, dunlin and sanderling (Jones & Key, 1989; Davidson et al., 1991).

Seasonal and longer term change

  • Vertical migrations from the substratum into the overlying sea water are made by the dominant crustaceans e.g. Eurydice pulchra and Bathyporeia pelagica. Such behaviour is endogenously controlled and has a circatidal rhythm that is coupled to a circasemilunar pattern of emergence (Alheit & Naylor, 1976; Fish & Fish, 1972; Preece, 1971; Fincham, 1970a & 1970b; Jones & Naylor, 1970; Watkin, 1939b).
  • Fish & Preece (1970) observed the disappearance of Bathyporeia pelagica from their sampling site in west Wales in March 1967 and specimens were not recorded again until October. In subsequent years the disappearance of Bathyporeia pelagica was sudden and characterized by the movement of a large proportion of the population to the lowest levels of the shore. The seasonal change was believed to be influenced by salinity-temperature fluctuations to which the species is intolerant.
  • Seasonal storm events can change sediment distribution and composition significantly e.g. the removal of the top 20 cm of sand has been reported (Dolphin et al., 1995).
  • Seasonal change has been documented for the meiofauna of sandy shores in temperate regions, with the meiofauna occurring in lower abundance and moving deeper into the sediment in winter (citations in McLachlan, 1983). Vertical migrations other than seasonal have been reported in response to heavy rain, wave disturbance, tidal factors and changes in moisture and oxygen over the tidal cycle.
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Habitat structure and complexity

The hydrodynamic regime (tides, waves and residual currents) together with the underlying physiography and geology create the conditions for a given substratum to develop. In terms of ecological relationships the interstices of the sand are significant owing to influences on the physical and chemical properties of the substratum to which the infauna are sensitive. Most physical properties of the interstitial system are directly determined by the sediment properties which in turn are related to the wave and current regime. Grain size, shape and degree of sorting are most important in determining porosity and permeability which influence drainage. Drainage is critical in determining the moisture content, oxygen saturation, organic content and the depth of the reducing layer (if present). Permeability increases with coarse substrate and better sorting, and drainage also increases on steeper beaches. The macrophyte community is poor owing to the lack of stable substrata, consequently the presence of occasional stones or an artificial substratum (e.g. coastal defences) would allow the establishment of some species of macrophyte e.g. Chorda filum.

Productivity

The primary production of sandy shores is very low if the sand is particularly clean, i.e. low in organic matter. Steele & Baird (1968) gave a figure of 5 g of carbon per m² per year for the productivity of a moderately exposed sandy beach. In most situations, diatoms are the primary producers of the depositing shore, and are confined to the illuminated sediment surface layers. The role of sulphur reducing bacteria is limited in clean sandy shore environments owing to the lack of an anoxic black sub-surface layer (under normal conditions). The phytoplankton of the sea becomes a temporary part of the sandy shore ecosystem when the tide is in and primary producers from other environments appear on the shore. These are invariably macroalgae that have become detached from rocky substrata and have been washed up, eventually they decompose on the beach and contribute to the energy budget of the shore system. Consequently most productivity on the depositing sandy shore may be categorised as secondary, derived from detritus and allochthonous organic matter, which is utilized by the fauna.

Recruitment processes

  • Eurydice pulchra breeds between April and August once sea temperatures rise above 10°C, and the highest number of juveniles occur around the periods of maximum summer temperatures. Males and females pair during their nightly swimming on falling spring tides and mating occurs in the sand once the female has completed her moult. Incubation of the embryo in the brood pouch takes some 7-8 weeks and after release of the young, the female returns to the non-breeding condition (J. Fish, pers. comm.). Juvenile Eurydice pulchra first appear in July, the minimum length being 1.7 mm (J. Fish, pers. comm.). Although the first juveniles may reach sexual maturity before the onset of winter, they begin breeding in the following spring and die during their second autumn after a total life span of approximately 15 months. Mid-summer juveniles also mature to breed the following summer and only reached 12 months of age before dying. In contrast, the last broods appearing as late as October, do not mature until late the following summer. They breed in their second October and then over-winter for a second time, producing a second brood in the spring before dying of at 18-20 months old (Hayward, 1994; Jones, 1970; Fish, 1970).
  • Bathyporeia pelagica may breed throughout the year, but the greatest reproductive activity occurs during spring and late summer/autumn. Males and females pair whilst swimming and mate on the night-time ebb tides following each new and full moon. Development of an egg to the stage when it is released as a juvenile takes about 15 days to complete. The over-wintering population of Bathyporeia pelagica consists largely of juvenile animals. These mature in spring to form the majority of the next breeding population and eventually die in June and July, after a life span of about one year (Fish & Preece, 1970). Bathyporeia pilosa has a similar recruitment cycle.
  • In Pontocrates arenarius from Irish Sea coasts breeding has been recorded throughout the year (Fish & Fish, 1996).
  • Little is known of the breeding patterns of Haustorius arenarius populations in Britain, but females with eggs are found during the summer months and longevity is believed to be two, possibly three years (Fish & Fish, 1996).
  • Scolelepis squamata from the south coast of England bred from March to at least July. The sexually mature worms are not pelagic. Fertilization is external and the larva is free swimming for about five weeks before settlement (Fish & Fish, 1996).
  • Important meiofaunal nematodes and harpacticoid copepods of the sandy shore are reported to have year round reproduction with generation times ranging from 1-3 months (McIntyre, 1969).

Time for community to reach maturity

Little evidence concerning community development was found and consequently information on the key species recruitment processes and longevity has been used to infer a time period of 1 to 2 years. One of the important characterizing species, Bathyporeia pelagica, produces a sequence of broods throughout the spring and summer which reach maturity within a year to produce subsequent generations. The meiofaunal community produces several generations within a year.

Additional information

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Preferences & Distribution

Recorded distribution in Britain and IrelandA common biotope that occurs on all coasts of Britain and Ireland, where the hydrodynamic regime and underlying topography and geology allow accumulation of sandy substrata. Largely absent in the south-east of England.

Habitat preferences

Depth Range
Water clarity preferences
Limiting Nutrients No information found
Salinity
Physiographic
Biological Zone
Substratum
Tidal
Wave
Other preferences No text

Additional Information

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Species composition

Species found especially in this biotope

Rare or scarce species associated with this biotope

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Additional information

No text

Sensitivity reviewHow is sensitivity assessed?

Explanation

Eurydice pulchra and Bathyporeia pelagica are both considered to be important characterizing species of the LGS.AEur biotope. In the absence of these species the biotope would not be recognised and would be more like the barren coarse sand shore biotope, LGS.BarSnd, which lacks a macrofaunal community.

Species indicative of sensitivity

Community ImportanceSpecies nameCommon Name
Important characterizingBathyporeia pelagicaAn amphipod

Physical Pressures

 IntoleranceRecoverabilitySensitivitySpecies RichnessEvidence/Confidence
High High Moderate Major decline High
The infauna reside in the uppermost layers of the substratum and removal of the substratum would cause a major decline in species richness, as they would be removed with it. Thus all the biotopes represented by this key information review have been assessed to be highly intolerant of substratum loss at the benchmark level. Recolonization by the important characterizing species is likely following deposition of a sandy substratum, therefore recovery has been assessed to be high. However, extensive areas of intertidal mud and sand flats have been lost through land-claim (Davidson et al., 1991) and should this biotope be covered over it would never recover.
Low Very high Very Low Rise Low
Smothering by 5 cm of sand is unlikely to affect adversely the important characterizing species which are able to burrow. Therefore, an intolerance of low has been recorded.

However, biotope intolerance is likely to be higher if the smothering sediment is atypical for the biotope e.g. fine silt or shingle, and assuming that the smothering materials were not rapidly removed or dispersed by the hydrographic regime, the atypical substrata would dramatically change the nature of the surface substratum. Over the duration of one month species not normally found within the biotope may find conditions favourable for colonization and the LGS.AEur biotope may start to shift to another community. The biotope would possibly not be recognized. Recovery has been assessed to be very high on return to prior conditions (see additional information below).

Tolerant Not relevant Not relevant No change Low
Increased suspended sediment derived from within the biotope, e.g. as the result of storm induced turbulence, is unlikely to be of significance to the important characterizing species as they do not suspension feed and therefore an assessment of not sensitive has been made.
Tolerant Very high Not sensitive* Minor decline Moderate
A decrease in suspended sediment may result in overall erosion of intertidal sands, where erosion is not compensated by deposition, but over the duration of one month effects are unlikely to be significant. The important characterizing species are not dependent on a supply of suspended material for feeding, so an assessment of not sensitive has been made.
Intermediate Very high Low Decline Low
In most circumstances, desiccation is unlikely to prove a lethal factor to the species of an established beach fauna, since the risk of drying up follows a regular pattern to which the species of the biotope have evolved both physiological and behavioural adaptations (Eltringham, 1971). The important characterizing species are mobile, with an endogenous swimming rhythm that is coupled to circasemilunar pattern of emergence, which serves to reduce the risk of animals being stranded high on the shore (Jones & Naylor, 1970; Fish & Fish, 1972; Alheit & Naylor, 1976). Other species of the community are infaunal and their environmental position and ability to bury deeper into the sand is likely to protect them from drying out. However, a change in desiccation may result as a consequence of alteration of the water table or beach gradient and hence drainage of the beach. The population residing in the upper facies of the beach are likely to avoid conditions to which they are intolerant and move seawards. The important characterizing species are unlikely to be destroyed but in their absence from the upper facies of the biotope, the biotope may not be recognized and intolerance has been assessed to be intermediate. Recovery has been assessed to be very high, as the species will recolonize as soon as conditions become tolerable.
Intermediate Very high Low Minor decline Moderate
Increased emergence (e.g. by tidal and storm surge barrages) is likely to increase the desiccation of the sediment, especially at the top of the shore and may consequently extend the extent of the barren sands biotope (A2.221), and potentially allow terrestrial plants, such as pioneer saltmarsh species e.g. Salicornia sp. or Spartina spp. to invade the very top of the shore. The important characterizing species of the biotope, Eurydice pulchra and Bathyporeia pelagica are both intertidal species which experience regular periods of emersion. Individually these species were assessed to have a low intolerance to an increase in the emergence regime owing to the fact that their environmental position and ability to burrow, would protect them to a greater extent from effects of desiccation. Scolelepis squamata appears to be capable of tolerating the well-drained sediments of this biotope and generally demonstrates a high tolerance to different environmental conditions (Souza & Borzone, 2000). However, Scolelepis squamata, is normally only present in the LGS.AEur biotope in low densities, so if already at the limit of its tolerance, an increase in the emergence regime may exclude it from the biotope. Furthermore, during an increased period of emergence (see benchmark), the populations of infaunal crustaceans may be susceptible to increased predation pressure by feeding wildfowl but at the expense of fish that feed in the intertidal. Intolerance to an increase in the emergence regime has been assessed to be intermediate. The key characterizing species of the biotope are unlikely to be destroyed by the factor but may experience a reduction in viability owing to predation pressure. In addition, the biotope may be effectively squeezed to the lower part of the shore (but not necessarily lost) as the upper facies of drying sand becomes more extensive. Recovery has been assessed to be very high (see additional information below).
Intermediate Very high Low Decline Moderate
The key characterizing species, Eurydice pulchra and Bathyporeia pelagica, were assessed not to be intolerant of a decrease in emergence regime. A decrease in the emergence regime may have implications for other species that utilize the biotope. For instance on the Oosterschelde, construction of a storm surge barrier resulted in the loss of 33% of intertidal habitat (Meire, 1993). Such a reduction in the exposed area or tidal range may increase the area available to fish for feeding, but at the expense of the wildfowl feeding period, which in turn reduces the carrying capacity of the area for wildfowl. The carrying capacity being reached when every new individual entering the habitat causes the emigration or death of another bird (Goss Custard, 1985). Intolerance has been assessed to be intermediate.
High High Moderate Decline Moderate
The nature of the substratum is, in part, determined by the hydrodynamic regime including water flow rate. Changes in the water flow rate will change the sediment structure and have concomitant effects on the community. The important characterizing species, Eurydice pulchraand Bathyporeia pelagica, demonstrated a preference for substrata of a specific grade (1.0-0.5 mm and 0.125-0.5 mm median diameter respectively). Although the species may not be directly exposed to the increased current, the factor would probably cause a redistribution/reduction of the preferred substrata and the species populations may become restricted or lost from a location. Consequently the biotope may no longer be identified in the location and intolerance has been assessed to be high. Recovery has been assessed to be high (see additional information below).
High High Intermediate Major decline Moderate
The nature of the substratum is, in part, determined by the hydrodynamic regime including water flow rate. Changes in the water flow rate will change the sediment structure and have concomitant effects on the community. The important characterizing species, Eurydice pulchraand Bathyporeia pelagica, demonstrated a preference for substrata of a specific grade (1.0-0.5 mm and 0.125-0.5 mm median diameter respectively). Although the species may not be directly affected by decreased current, it would probably cause the accretion of finer particulate and organic matter and to which the important characterizing species are intolerant and the species populations may become restricted or lost from a location. The accretion of muds and organic matter would encourage littoral mud communities to develop and the LGS.AEur biotope, and others represented by this review would no longer be recognised. Therefore intolerance has been assessed to be high. Recovery has been assessed to be high (see additional information below).
Low Very high Very Low Minor decline Low
Many intertidal species are adapted to temperature extremes, can alter metabolic activity, burrow deeper in sediment or move to deeper water. At low tide, air temperature becomes critically important to intertidal animals, and on sandy beaches the substratum, from the surface to a depth of several centimetres, can experience large variations in temperature during a single cycle and throughout the year (Hayward, 1994). For instance, Khayrallah & Jones (1980b) reported the temperature range of sand at a depth of 1 cm during neap tides to be from -2°C in February 1973, to a maximum of 25°C in July 1977. Although adapted to temperature change, severe acute change may result in seasonal reduction in species richness and abundance, but the effects of an acute temperature increase are not necessarily direct and may be more related to the resultant changes in other factors, especially oxygen resulting from enhanced microbial activity (Hayward, 1994; Eltringham , 1971). Intolerance has therefore been assessed to be low and variable.
Low Very high Moderate Minor decline Low
Many intertidal species are adapted to temperature extremes, can alter metabolic activity, burrow deeper in sediment or move to deeper water. Although adapted to temperature change, severe change may result in seasonal reduction in species richness and abundance. At low tide, air temperature becomes critically important to intertidal animals, and on sandy beaches the substratum, from the surface to a depth of several centimetres, can experience large variations in temperature during a single cycle and throughout the year (Hayward, 1994). For instance, Khayrallah & Jones (1980b) reported the temperature range of sand at a depth of 1 cm during neap tides to be from -2°C in February 1973, to a maximum of 25°C in July 1977. The effect of an unusually cold winter on the infauna is a simple physical one, in which body fluids freeze, causing cell and tissue damage. However, Crisp (1964) reported that species of amphipod and isopods seemed to be unharmed by the severe winter of 1962-1963 and intolerance has been assessed to be low.
Tolerant Not relevant Not relevant No change Moderate
Primary productivity due to pelagic phytoplankton and microphytobenthos contribute to intertidal benthic communities and is light limited. Incoming tides and wave action suspend sediment resulting in high local turbidity, so microphytobenthos normally experience light limiting conditions periodically. However, the majority of productivity in these biotopes is secondary (detritus) and the biotope has been assessed to be not sensitive to the light attenuating effects of an increase in turbidity.
Tolerant Not sensitive* No change Moderate
A decrease in turbidity, possibly associated with a decrease in wave action, may allow fish to hunt more efficiently, as prey items such as the crustaceans become more visible when swimming. However, as the important characterizing species are likely to be not sensitive to an increase in light penetration, the biotope has been assessed not to be sensitive.
High High Moderate Major decline Moderate
Wave action determines the slope and width of sandy intertidal areas. An increase in wave exposure would alter the habitat through increased erosion (which may not be compensated for by deposition) and ultimately the nature of the substratum would change becoming coarser, forming deposits of shingle or gravel rather than sand, creating conditions outside the species habitat preference. Intolerance has been assessed to be high as the important characterizing species would probably no longer be found. Recovery has been assessed to be very high, for instance, at Village Bay on St Kilda, an island group far out into the Atlantic west of Britain, an expanse of sandy beach was removed offshore as a result of winter storms to reveal an underlying rocky shore (Scott, 1960). Yet in the following summer the beach was gradually replaced when wave action was less severe. Eurydice pulchra was a species reported to be a frequent member of the re-colonizing fauna, its recovery being aided by the ability to survive in the shallow sublittoral zone where substrata may be deposited.
High High Intermediate Major decline Moderate
Wave action determines the slope and width of sandy intertidal areas. Decreases in wave exposure would probably cause accretion of finer sands, silts and clays and lessen the slope of the shore, which in turn would alter drainage and the oxygenation of the substratum. Opportunistic species, more typically associated with muddy littoral biotopes, may colonize the biotope. The important characterizing species of the LGS.AEur biotope, and others represented by this review, demonstrated a preference for clean relatively well drained sand, and may be exposed to unfavourable conditions. In the absence of these species the biotope may no longer be recognisable. Therefore intolerance has been assessed to be high. Recovery has been assessed to be high on return to prior conditions (see additional information below).
Tolerant* Not relevant Not sensitive* Not relevant Moderate
Disturbance by noise and visual presence of human activities will be considered together. Disturbance causes birds that frequent the biotope to fly away. A reduction in predation pressure may benefit infaunal populations of crustaceans and polychaetes and therefore an intolerance assessment of not sensitive* has been made. For information, disturbance tolerance by birds is species dependant, some species habituating to noise and visual disturbance while other become more nervous. For example brent geese, redshank, bar-tailed godwit and curlew are more 'nervous' than oyster catcher, turnstone and dunlin. Turnstones will often tolerate one person within 5-10m. However, one person on a tidal flat can cause birds to stop feeding or fly off affecting c. 5 ha for gulls, c.13ha for dunlin, and up to 50 ha for curlew (Smit & Visser 1993). Goss-Custard & Verboven (1993) report that 20 evenly spaced people could prevent curlew feeding over 1000 ha of estuary.
Tolerant* Not relevant Not sensitive* Not relevant Moderate
Disturbance by noise and visual presence of human activities will be considered together. Disturbance causes birds that frequent the biotope to fly away. A reduction in predation pressure may benefit infaunal populations of crustaceans and polychaetes and therefore an intolerance assessment of not sensitive* has been made.
Low Very high Very Low Minor decline Moderate
Abrasion is unlikely to affect the infaunal species of this biotope. Species such as amphipods and isopods may be small enough to avoid damage. The tops of polychaete burrows may be damaged and repaired subsequently at energetic cost to their inhabitants. In other biotopes represented by this review, the bivalve, Angulus tenuis, may be abundant and is an important food source for young plaice. This brittle bivalve may be damaged by abrasion from objects impacting and dragging through the sand, therefore A2.223, , and may be more intolerant than the LGS.AEur biotope, but intolerance has been assessed to be low. Recovery has been assessed to be very high as a proportion of the tellin population is likely to remain undamaged and it breeds annually.
Tolerant Not relevant Not relevant No change High
The important characterizing species, Eurydice pulchra and Bathyporeia pelagica, are both mobile species and leave the protection of the substratum regularly owing to their endogenous swimming rhythm. The polychaete, Scolelepis squamata, lives infaunally in vertical tubes formed from sand and mucus and is associated with the swash and surf zones of high energy sandy beaches (Dauer, 1983). Scolelepis squamata has been observed to swim and significant seasonal changes in its distribution within the swash and surf zones have been reported, indicating that the species is able to re-establish itself within the substratum following displacement. The biotope community has been assessed to be not sensitive to displacement.

Chemical Pressures

 IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
High Moderate Moderate Major decline Low
Areas of sandy intertidal adjacent to industrialised and urbanised estuaries and coastlines may receive effluent discharges which contain a variety of synthetic conservative contaminants, i.e. those with a long half-life are likely to bioaccumulate and thus have a toxic effect (Clark, 1997). In general, crustaceans are widely reported to be intolerant of synthetic chemicals (Cole et al., 1999) and intolerance to some specific chemicals has been observed in amphipods. Powell (1979) inferred from the known susceptibility of Crustacea to synthetic chemicals and other non-lethal effects, that there would probably also be a deleterious effect on isopod fauna as a direct result of chemical application. Smith (1968) found that, at a concentration of 10 ppm, the oil dispersant BP 1002 killed the majority of Eurydice pulchra in 24 hours at 12°C. However, in the field a proportion of the Eurydice pulchra population survived exposure to lethal concentrations of BP 1002, both in the sand and water.
It is apparent that different taxa of the biotope are likely to differ in their susceptibility to different synthetic chemicals and that this may be related to differences in their physiology (Powell, 1979). Consequently, in the absence of evidence to the contrary and owing to the diversity of synthetic chemicals to which the biotope may be exposed, intolerance has been assessed to be high. Recovery requires dilution, biodegradation or removal of the contaminant from the sediments which may take several years, and recoverability has therefore been assessed to be moderate.
Heavy metal contamination
Intermediate Moderate Moderate Decline Low
For most metals, toxicity to crustaceans increases with decreased salinity and elevated temperature, therefore marine species living within their normal salinity range may be less susceptible to heavy metal pollution than those living in salinities near the lower limit of their salinity tolerance (McLusky et al., 1986).
Jones (1973; 1975b) found that mercury (Hg) and copper (Cu) reacted synergistically with changes in salinity and increased temperature (10°C) to become increasingly toxic to species of isopod, including Eurydice pulchra. Intolerance has been assessed to be intermediate specifically because alterations in salinity and temperature influence the effect of heavy metals on the community and the entire population may not be destroyed but may experience sublethal effects which may reduce the viability of the population. Recovery requires dilution, biodegradation or removal of the contaminant from the sediments which may take several years. Therefore recoverability has been assessed to be moderate.
Hydrocarbon contamination
High Moderate Moderate Major decline High
Oil spills result in large scale damage to intertidal communities. Oil smothers sediments preventing oxygen exchange, producing anoxia and death of infauna. Stranded oil penetrates the sediment, especially sands due to wave and tidal action and destabilises the sediment. Microbial degradation of the oil increases the biological oxygen demand and hence anoxia. Amphipods have been reported to be particularly intolerant of oil pollution (Suchanek, 1993). After the Amoco Cadiz oil spill there was a reduction in both the number of amphipod species and the number of individuals (Cabioch et al., 1978). Initially, significant mortality would be expected, attributable to toxicity and the effects of smothering, therefore intolerance has been assessed to be high as amphipods are important characterizing species in all the biotopes represented by this review. Often populations do not return to pre-spill abundances for 5 or more years, which is most likely related to the persistence of oil within sediments (Southward, 1982) and recoverability has therefore been assessed to be moderate.
Radionuclide contamination
No information Not relevant No information Not relevant Not relevant
Radionuclides can accumulate within substrata in a similar way to heavy metals. However, there is little information concerning their biological effects (Cole et al., 1999).
Changes in nutrient levels
High High Moderate Major decline High
The effects of organic enrichment on sedimentary systems and their benthos is well documented and shows a consistent sequence of response - the Pearson-Rosenberg model (Pearson & Rosenberg, 1978). Greater organic inputs, coupled with reduced oxygenation lead to conditions of slow degradation and create anaerobic chemical conditions within the sediment. In turn, microbial activity is enhanced whilst the redox potential of the sediments is reduced which in turn increases the production of hydrogen sulphide and methane (Fenchel & Reidl, 1970). A state of anaerobiosis limits the macroinfauna to species which can form burrows or have other mechanisms to obtain their oxygen from the overlying water. Moderate enrichment provides food which enhances species abundance, whilst a mixing of organisms with different responses initially increases diversity (Elliott, 1994). With greater enrichment, the diversity declines and the community becomes increasingly dominated by a few pollution tolerant, opportunistic species such as the polychaete Capitella capitata.
For instance, prior to the introduction of a sewage treatment scheme in the Firth of Forth, the communities of several sandy beaches were considerably modified by gross sewage pollution (Read et al.,1983). The west end of Seafield beach exhibited extremely reduced diversity with a community dominated by Scolelepis fuliginosa and Capitella capitata, to the almost exclusion of all other species of macrofauna. However, at Portobello beach, a reduction in the number of species was recorded and the presence of a 'dominant' replacement community was less obvious. Furthermore, in 1977, before the introduction of the sewage scheme, meiofauna population counts at Seafield and Portobello were also conspicuously lower than for other Scottish beaches (McIntyre, 1977). Many of the major taxa commonly associated with marine intertidal meiobenthos were scarce or absent. Only nematodes, gastrotriches, harpacticoids and turbellarians were commonly identified from samples, nematodes being the most abundant taxon.
intolerance to nutrient enrichment has been assessed to be high owing to the resultant modification of the faunal community. Following sewage pollution abatement in 1977, dramatic changes in the macrofauna occurred. The Scolelepis / Capitella community declined steadily throughout 1978-1979, so that by spring 1980 species normally associated with 'cleaner' sandy beaches were recorded e.g. Microthalmus sp., Ophiodromus flexuosus, Eulalia viridis, Eurydice pulchra and Monoculodes sp., but not at pre-impact abundances. There was also an increase in meiofaunal diversity and reduction in dominance by certain taxa. Recovery has been reported to be high as full recovery is likely to take several years.
Low Very high Very Low Insufficient
information
Low
Salinities higher than that of seawater are uncommon, although surface pools may increase in salinity owing to evaporation in hot conditions. However, owing to the relatively well drained nature of the substratum in the LGS.AEur biotope, pooling of surface water is unlikely and the infaunal species may avoid the factor by burrowing. Intolerance has been assessed to be low in light of lack of evidence to the contrary. Recovery has been assessed to be very high because the important characterizing species are abundant and would rapidly repopulate areas of localised reduced abundance.
Low Very high Moderate Minor decline Moderate
Intertidal sands may be exposed to rainfall at low tide, however, freshwater sits on the surface of denser seawater and interstitial water remains close to full salinity. In order to tolerate salinity changes, species may osmoregulate, may stop irrigating their burrow, or may move seaward if mobile or burrow deeper into the sediment (McLusky 1989). Freshwater flowing seaward over sandflats may have a localised effect on species diversity and abundance. Eurydice pulchra was found to be relatively euryhaline (Jones, 1970b), whilst Bathyporeia pelagica migrates seaward in response to reduced salinities, the effect of which is enhanced by higher temperature (Preece, 1970). An intolerance assessment of low has been made, owing to the lack of mortalities arising from reduced salinities in the field. Recovery has been assessed to be very high because the important characterizing species are abundant and would rapidly repopulate areas of localised reduced abundance.
High High Moderate Major decline Very low
Coarse sands may have relatively high oxygen concentration and a lack a black reducing layer. Brafield (1964) concluded that the most significant factor influencing the oxygenation is the drainage of the beach which, in turn, is determined by the slope and particle size. Oxygen depletion becomes a severe problem at all states of the tide on only the finest grained beaches, and as a general rule, if the percentage of particles of less than 0.25 mm in diameter exceeds 10% of a sand, then the oxygen concentration of its interstitial water will be less than 20 % of the air saturation level, and will drop rapidly during low tide periods. As the LGS.AEur biotope community is not normally exposed to conditions of anoxia it has consequently been inferred that the biotope community would have a high intolerance to a decrease in oxygenation at the benchmark level. On return to prior conditions, re-population is likely and has been assessed to be high (see additional information below).

Biological Pressures

 IntoleranceRecoverabilitySensitivityRichnessEvidence/Confidence
No information Not relevant No information Insufficient
information
Not relevant
The most common parasites of sand inhabiting invertebrates belong to the Trematoda, a class of the phylum Platyhelminthes, and to the Copepoda, a group of crustaceans whose free living members are either planktonic or sediment dwelling. Trematodes (flukes) usually have three consecutive hosts, although two to four are known. In the marine environment, the primary hosts are normally fish or birds, and the first secondary host a gastropod or bivalve mollusc. The second intermediate host may belong to a variety of taxonomic hosts including the coelenterates, turbellarians, annelids, crustaceans, molluscs, insects or fish (Eltringham, 1971). However, an intolerance assessment for the biotopes represented by this review cannot be made owing to insufficient information concerning impacts on the population.
No information Not relevant No information Not relevant Not relevant
Insufficient
information.
Intermediate Very high Low Minor decline Moderate
None of the important characterizing species of the LGS.AEur, LGS.AP, LGS.AP.P & LGS.AP.Pon biotopes are targeted for extraction. However, Arenicola marina occurs in the biotopes LGS.AP and LGS.AP.P, which have a more diverse polychaete community than LGS.AEur. Arenicola marina is targeted by bait diggers who extract the species both manually and mechanically. Mechanical lugworm dredging is more severe and can result in the complete removal of Arenicola marina (Fowler, 1999). McLusky et al. (1983) examined the effects of bait digging on blow lug populations in the Forth estuary. Dug and infilled areas and unfilled basins left after digging re-populated within 1 month, whereas mounds of dug sediment showed a reduced population. Basins accumulated fine sediment and organic matter and showed increased population levels for about 2-3 months after digging. Overall recovery is generally regarded as rapid. However, Fowler (1999) pointed out that recovery may take longer on a small pocket beach with limited possibility of recolonization from surrounding areas. Therefore, if adjacent populations are available recovery will be rapid and a rank of 'very high' has been given. However where the affected population is isolated or severely reduced (e.g. by long-term mechanical dredging), then the recovery period may be extensive.
Intermediate Very high Low Decline High

Additional information

Recoverability
Little evidence concerning community development was found and consequently information on the important characterizing species recruitment processes and longevity has been used to infer a time period of 1 to 2 years for the community to recover. One of the important characterizing species, Bathyporeia pelagica, produces a sequence of broods throughout the spring and summer which reach maturity within a year to produce subsequent generations. The meiofaunal community produces several generations within a year.

Importance review

Policy/Legislation

- no data -

Exploitation

The biotope is not targeted for commercial exploitation, but is likely to be used for recreational purposes in popular tourist areas.

Additional information

-

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Citation

This review can be cited as:

Budd, G.C. 2004. Eurydice pulchra in littoral mobile sand. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. Available from: http://www.marlin.ac.uk/habitat/detail/344

Last Updated: 12/11/2004