Crustacea: Ostracoda

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The distribution and assemblage composition of the ostracod fauna (Crustacea: Ostracoda) on Filey Brigg, North Yorkshire S.L. Hull

a

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University College Scarborough , Filey Road, Scarborough, North Yorkshire, YO11 3AZ, UK Published online: 17 Feb 2007.

To cite this article: S.L. Hull (1998) The distribution and assemblage composition of the ostracod fauna (Crustacea: Ostracoda) on Filey Brigg, North Yorkshire, Journal of Natural History, 32:4, 501-520, DOI: 10.1080/00222939800770271 To link to this article: http://dx.doi.org/10.1080/00222939800770271

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JOURNAL OF NATURAL HISTORY, 1998, 32, 5 0 1 - 5 2 0

The distribution and assemblage composition of the ostracod fauna (Crustacea: Ostracoda) on Filey Brigg, North Yorkshire S. L. H U L L

University College Scarborough, Filey Road, Scarborough, North Yorkshire, Y O l l 3AZ, UK

Downloaded by [University of Hull] at 07:44 12 February 2015

(Accepted 29 September 1997) Intertidal algae from rockpools at different tidal heights, along with Laminaria holdfasts and samples of sublittoral algae were collected from both the sheltered and exposed side of Filey Brigg, North Yorkshire. Samples of sediments were also collected from MLWS on the sheltered shore. A total of 1091 individual ostracods, consisting of 32 species, from 20 genera and 12 families, were identified from 15 sites along the Brigg in July 1996. The current study lists the occurrence of thirteen species previously unrecorded for the Yorkshire coast, and confirms presence of three species that were thought to have a general distribution around the British Isles. The seven Paradoxostoma species showed distinct zonation patterns on both the sheltered and exposed shore. Paradoxostoma ensiforme and P. variabile were only found intertidally, P. hibernicum decreased numerically down shore, and P. bradyi and P. abbreviatum were only found in low shore, Laminaria holdfast or sublittoral samples. This pattern was also seen in many other species, e.g. Xestoleberis aurantia, which only occurred in the intertidal phytal samples, whereas others were only found sublittorally, e.g. Selerochilus

truneatus. Cytherois fischeri, Paradoxostoma robinhoodi, Hemicytherura cellulosa, Leptocythere psammophila, Semicytherura sella and Sclerochilus gewermuelleri were found on the exposed shore only and Cuneocythere semipunctata only occurred on the sheltered shore. Apart from these differences in distribution, the other species occurred on both sides of the Brigg, with only minor differences in density. Some species were more numerous on the sheltered shore (e.g. Heterocythereis albomaculata), whereas others occurred in higher frequencies on the exposed shore (e.g.P. hibernicum). However, there was no marked difference in assemblage structure between the sheltered and exposed side of Filey Brigg. The intertidal phytal assemblages then showed a high degree of similarity. However the sublittoral assemblages were markedly dissimilar from the highshore assemblages and there was little similarity between the intertidal phytal and sediment assemblages. Although some species occurred in both habitats, e.g. Cythere lutea, others were only found in either one or the other. The phytal assemblages had a higher species richness of ostracods and were more diverse than the sediment assemblages. However, there was no correlation between phytal ostracod species diversity and tidal height, or between diversity and sediment content of the algae. The Yorkshire coast ostracod fauna is compared and contrasted with that previously described by other workers from southern and western Britain. KEYWORDS" Marine ostracods, zonation, assemblage structure, meiofauna.

Introduction O s t r a c o d s h a v e an extensive fossil h i s t o r y a n d wide g l o b a l d i s t r i b u t i o n ( b o t h in freshwater a n d m a r i n e e n v i r o n m e n t s ) , a n d for m a n y years t h e y have been used as 0022-2933/98 $12"00© 1998Taylor&FrancisLtd.


502

S.L. Hull

indicators of past climate and environmental change (Neale, 1964). Due to their usefulness as indicator species, their distribution in sediments dating back to the Cambrian period has been documented (Brasier, 1995). More recent studies confirm the assessment of environmental change (e.g. Boomer et al., 1996), but also illustrate the need for baseline data in order to determine the magnitude and direction of the changes in species abundance and assemblage composition. Apart from the work of various dedicated and distinguished ostracod taxonomists who have described some extant ostracod faunas in detail, the majority of current publications deal with fossil, rather than extant assemblages. Therefore there is a need to describe and understand the dynamics and composition of modern assemblages in order to detect any changes which may result from natural or anthropogenic origins. Most studies centred upon the study of the structure of phytal epifaunal communities do not classify ostracods down to species level (e.g. Coleman, 1939; Dommasnes, 1969), although more recent studies have begun to address the problem (e.g. Preston and Moore, 1989; Jarvis and Seed, 1996). In the UK, phytal ostracod assemblages have been described in some detail from South Wales (Whatley and Wall, 1975; Trier, 1993), Anglesey (Williams, 1969), the Isles of Scilly (Neale, 1970), the Bristol Channel (Horne, 1982b), and Plymouth (Elofson, 1940). However, despite the descriptive work of Victorian taxonomists, e.g. Brady (1868) and Brady and Norman, (1889), plus samples collected for recent taxonomic revisions (e.g. Horne and Whittaker, 1985; Athersuch and Horne, 1987), and a survey of the fauna of kelp holdfasts (Moore, 1973), little appears to be known about the distribution of species and the structure of ostracod assemblages on the North Sea coast of England. Wieser (1952) found no correlation between tidal height and the distribution of ostracods during a study of the phytal assemblages on the shore in front of the Plymouth marine laboratory. However, Whatley and Wall (1975), from a study in the vicinity of Aberystwyth, suggested that some littoral species prefer certain shore zones but that the overall pattern was confused due to the differential distribution and survival of the animals on different algal species. In Norway, only four ostracod species were permanent residents of Corallina officinalis (L.), although a further nine species were found intermittently throughout the year (Hagerman, 1968). The relationship between ostracods and algae appears to be complex. Ostracod distribution and occurrence may be dependent upon algal morphology, seasonal development of the algae, sediment content and the microhabitat of the algal species as well as being related to general zonation patterns (Whatley and Wall, 1975). For the aforementioned reasons, the current study focuses on a community approach to the study of phytal ostracod distributions, investigating the distribution of ostracods in rockpools collected from a mixture of algal species at given shore heights. The aims of the current study were: (1) to compile a list of extant species from a variety of habitats on Filey Brigg; (2) to compare the composition of ostracod assemblages found at different sites in close proximity (both phytal and sedimentary); and finally, (3) to contrast the assemblage found on the N.E. coast of England with those previously described in the literature from S.W. Britain. Method and materials

Sample collection and identification Samples of sediment and algae were collected from 15 sites along Filey Brigg, North Yorkshire (O.S. Grid Reference TA/128816) during one week of spring tides

Ostracods of Filey Brigg

503

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Scale 200m

FIG. 1. Map of Filey Brigg (54° 13%1, 00° 15%V) showing sediment sample collection sites and the location of the transects from which the phytal samples were taken. E = exposed shore, S = sheltered shore. in July 1996. This site was chosen as it presents a variety of habitats, both phytal and sedimentary, under both sheltered and exposed conditions all within a small area, thus it was possible to associate changes in faunistic composition with physical features of the habitat. Samples of mixed algae were collected from both the sheltered and exposed side of the Brigg from 10cm depth in similarly-sized rockpools at each of three shore heights (MHW, Mid-shore and MLW) plus a further three samples of holdfasts from the Laminaria digitata zone (figure 1). Sublittoral algae were collected from a depth of 10m below Chart Datum on both the sheltered and exposed side of Filey Brigg during the same month from a 1 m quadrat using SCUBA equipment. The samples of algae collected from the sheltered (S) and exposed (E) shores are described in table 1, along with the dry weight of algal material and sediment content for each sample. Samples of sediment (100 g) were also collected at MLWS from various littoral sites along the sheltered side of Filey Brigg (there was no accessible sediment on its exposed side). Fine sand was collected from the dense beds of Ulva lactuca at the end of the Brigg (S1), silt from Modiolus beds ($2), fine sand trapped by the red alga Audouinella spp. ($3), fine sand/silt from the corner of the till cliffs ($4), and a sample of medium-grained sand from the beach 100m from $4 ($5). In the laboratory, ostracods were removed carefully from the algae by washing the algae in 4% formalin in seawater through 1 mm, 250 #m and 65 #m sieves. The sediment from the algae was collected and dried to estimate the weight of trapped sediment. The algae were then checked to ensure that all the ostracods had been removed, and then the samples dried then weighed. The ostracods were handpicked from the sieves and stored in 70% alcohol until required for analysis. The sediments were also sieved through the same sieves and the ostracods picked from the sieves and stored as for the phytal samples. Identification was done using both a highpower microscope and binocular microscope. All identification and taxonomy is based upon that of Athersuch et al. (1989), and the results are expressed as number of ostracods per 30 g dry weight of algal tissue, or per 100 g of sediment. Data analysis To provide a qualitative index of faunal similarity, Czekanowski's coefficient (QS) (Hicks, 1980) was calculated from binary presence/absence data to examine

Eh

Em

El

Ela Esub

Sh

Sm

Sl

Sla

Ssub

Mid-shore

MLW

Laminaria Sub-littoral

Sheltered MHW

Mid-shore

MLW

Laminaria

Sub-littoral

Sample designation

Exposed MHW

Sample

Corallina officinalis, Hypoglossum hypoglossoides, Plocamium eartilaginum, Delessaria sanguinea, Desmarestia ligulata

Enteromorpha intestinalis, Blidingia, Spongomorpha arcta, Fucus spiralis Coralina officinalis, Ulva lactuca, Cladophora rupestris, Ceramium rubrum, Fucus vesiculosus Corallina officinalis, Fucus serratus, Ceramium rubrum, Gracilaria verrucosa, Cladophora rupestris Laminaria digitata

Enteromorpha intestinalis, Blidingia, Spongomorpha arcta, Fucus spiralis Corallina officinalis, Ulva lactuca, Cladophora rupestris, Ceramium rubrum, Fueus vesiculosus Corallina officinalis, Fucus serratus, Ceramium rubrum, Gracilaria verrucosa, Cladophora rupestris Laminaria digitata Corallina officinalis, Hypoglossum hypoglossoides, Plocamium eartilaginum, Delessaria sanguinea, Desmaretia liguIata

Species

24.5

25.6

27'1

35-9

32"4

35-3 25.6

31"8

28"2

33'5

Dry weight of algae (g)

Table 1. Description of the phytal samples collected from Filey Brigg.


Fine sand, shell fragments Fine sand, silt

Fine sand, silt

Fine sand, silt

Fine sand, silt

Shell fragments, sand Fine sand, silt

Fine and coarse sand

Fine and coarse sand

Coarse sand

Sediment type

5"3

4.6

10"9

9-5

5'7

3-0 3"4

5-0

4'2

6"1

Sediment content (g)

.t-" ~Z

4~


505

the species association between samples, i.e. QS = 2j/(a + b) Where j = t h e number of joint occurrences of a species, and a and b are the total number of species found in each sample. Classification was achieved using the BrayCurtis similarity coefficient to construct dendrograms (Ludwig and Reynolds, 1988). Sample diversity, evenness and species richness were calculated using the Shannon Wiener diversity index and modified Student's t-tests calculated to determine if there was any significant difference in diversity between samples (Magurran, 1988). All other statistical analyses were done using Minitab© for Windows.


Results A total of 1091 ostracods, consisting of 32 species from 20 genera and 12 families, were identified from the 15 sites along Filey Brigg. It appears from the literature that 13 of these species have not been previously recorded for the east coast of England. A further 19 species were identified from valves and complete carapaces but are not included herein. Appendix 1 summarizes the occurrence and relative abundance of the 32 species sampled.

Extant ostracod species found at Filey Brigg ORDER PODOCOPIDA SUPERFAMILY CYTHERACEA

Family Cuneocythevidae Mandelstam, 1959 Genus Cuneocythere Lienenklaus, 1894 Cuneocythere semipunctata (Brady, 1868) One live adult found amongst the holdfast of Ssub. Family Cytheridae Baird, 1850 Genus Cythere O. F. Mtiller, 1785 Cythere lutea (O. F. Mtiller, 1785) A very common species with a ubiquitous distribution. Both adults and juveniles were found amongst the algae at all the tidal levels on both the sheltered and exposed shore. This species accounted for 18-1% of the Eh fauna, 5-3% of the Era, 33"7% of the El and 2.6% of the Ela fauna on the exposed shore. Similarly, on the sheltered shore this species accounted for 41.8% of the Sh, 26.3% of the Sm, 37"2% of the SI and 16.6% of the Sla. Live adults were also found in 4 out of 5 of the sediment samples collected, being absent only from $4. Family Cushmanideidae Puri, 1974 Genus Pontocythere Dubowsky, 1939 Pontocythere elongata (Brady, 1868) Live animals recovered from $5, and complete carapaces recovered from $4. Family Leptocytheridae Hanai, 1957 Genus Callistocythere Ruggieri, 1953 Callistocythere badia (Norman, 1862)

506

S.L. Hull

Live adult females (no males) found only in the Eh assemblages on the exposed shore, accounting for 11.8% of the ostracod fauna. Genus Leptocythere Sars, 1925 Leptocythere pellucida (Baird, 1850) Amongst algae in both sheltered (Sh=0-7% of the fauna) and exposed (Eh= 2.3%) pools, and also live individuals from $5 (35%). Complete carapaces and both left and right valves were also found in $5 and $4. Leptocythere psammophila Guillaume, 1976


Live animals found in $5 and amongst Ela holdfasts (3.3% of the fauna). Carapaces were also found in all the sediment samples except $3. Family Cytheruridae G. W. Mt~ller 1894 Genus Hirschmannia Elofson, 1941 Hirschmannia viridis (O. F. M~iller, 1785) Live juveniles found amongst algae only in mid-shore pools (Sm =22.8% of the fauna) and exposed shore (Em = 3%). Right valve of adult carapace found in $5. Genus Loxoconcha Sars, 1866 Loxoeoncha rhomboidea (Fischer, 1855) One live adult and right valve found in $5. Genus Palmoconcha Swain and Gilby, 1974 Palmoconeha laevata (Norman, 1865) Live individuals found amongst algae from Em (1.2% of fauna) and El (3.7%) pools on the exposed shore. Live individuals also recovered from $4 and $5. Family Hemicytheridae Puri, 1953 Genus Hemicythere Sars, 1925 Hemicythere villosa (Sars, 1866) Live animals found in Eh (5.9% of the fauna), El (3"7%), Ela (6-7%) and from Esub (5.7%) on the exposed shore. Complete carapaces found in S1, $2, $5 and $3 along with individual valves. Genus Heterocythereis Elofson, 1941 Heterocythereis atbomacutata (Baird, 1838) A common species accounting for 5-12-9% of the fauna at all tidal heights from algae on the exposed shore, and 9"5 24% of the fauna at all tidal heights on the sheltered shore. Live animals also found amongst $3, $4, and $5 along with the complete carapaces and valves of both adults and juveniles. Genus Urocythereis Ruggieri, 1950 Urocythereis britannica Athersuch, 1977


507

Live animals found in S1 and $2 along with a complete carapace. Family Paradoxostomatidae Brady and Norman, 1889 Genus Paradoxostoma Fischer, 1855 Paradoxostoma abbreviatum Sars, 1866 Live animals recovered from Eh (1.3% of the fauna), Ela (3'3%) and Esub (12.8%) on the exposed shore and also from Ssub (14.3%) on the sheltered shore. Complete carapaces were also found in $5.


Paradoxostoma bradyi Sars, 1928

On the exposed shore, found amongst algae in El (20% of the fauna), Ela (20%) and Esub (4-3%). A similar pattern was found on the sheltered shore, S1 (4.4%), Sla (5-5%) and within Ssub (21-4%). Both adults and juveniles were present. Complete carapaces were also found in $4 and $5. Paradoxostoma ensiforme, Brady, 1868

A common intertidal species. However it was not found amongst the algae from the Eh pools nor in the sub-littoral sample, but accounted for 45.1% of the Em fauna, 3.7% of the El, and 23.3% of Ela fauna. On the sheltered shore this species accounted for 3"7% of the Sh fauna, 7% of the Sin, 15% of the Sl, 5.5% of the Sla and 7-1% of the Ssub fauna. This species was not found amongst the sediment samples. Both adults and juveniles were present in all samples. Paradoxostoma hibernicum Brady, 1868

Both adults and juveniles were found intertidally amongst the algae on both the sheltered and exposed shores. Accounted for 14.1% of the fauna in Eh, 4% of Em, and 3.7% of the El fauna on the exposed shore, and 15.5% of the Sh, 9.5% of the Sm and 15% of the Sl fauna on the sheltered shore. No individuals were recovered from the Laminaria holdfasts nor from the sublittoral algae, and this species was absent from the sediment samples. Paradoxostoma nealei Horne and Whittaker, 1985

Adults found in the Em samples from the exposed shore accounting for 1.6% of the fauna. On the sheltered shore, accounted for 3"5% of the Sm and 6.2% of the Sl fauna. No individuals were recovered from the Laminaria holdfasts, sublittoral algae or the sediment samples. Paradoxostoma normani Brady, 1868

A rare species, not recorded from any of the samples collected from the exposed shore, and only found in the sheltered shore Sl algae, accounting for 0-8% of the fauna. Not present in the sediment samples. Paradoxostoma robinhoodi Horne and Whittaker, 1985

Not recovered from the intertidal zone or sub-littoral algae on the sheltered shore, or from the sediment samples. Accounted for 2.8% of the Em, 2.5% of the El, 3.3% of Ela and 18.6% of the Esub fauna on the exposed shore. Only adults present.

508

S.L. Hull

Paradoxostoma varh~bile(Baird, 1835) A common intertidal species, accounting for 3"5% of the Eh, 17.5% of the Em, 21"3% of the El and 20% of the Ela fauna on the exposed shore. A similar pattern was observed on the sheltered shore, with this species accounting for 2.3% of the Sh, 7% of the Sm and 15-9% of the Sl fauna. This species was not found sublittorally nor in the sediment samples. Genus Cytherois G. W. Miiller, 1884 Cytheroisfischeri (Sars, 1866)


Individuals of this species were not recorded from the sheltered shore samples, nor the sediment samples. This species was only found in the Em pools of the exposed shore accounting for 1.6% of the fauna. Family Cytherideidae Sars, 1925 Genus Sarsicytheridea Athersuch, 1982 Sarsicytheridea punctillata (Brady, 1865) Live animals found in Sl, and complete carapaces recovered from $2 and $4 and one right valve from $5. Family Bythocytheridae Sars, 1928 Genus Bythocythere Sars, 1866 Bythocythere bradyi Sars, 1926 Live animals recovered from $4, and complete carapaces recovered from $5. Genus Sclerochilus Sars, 1866 Sclerochilus abbreviatus Brady and Robertson, 1839 Not found in the intertidal samples or sediment samples, but accounted for 21.4% of the Ssub and 5-7% of the exposed shore Esub samples. Sclerochilus gewemuelleri Dubowsky, 1939 Only found from the exposed shore Esub sample accounting for 10% of the fauna. Sclerochilus hicksi Athersuch and Horne, 1987 Only found in the sub-littoral samples, accounting for 7-1% of the Ssub and 8.6% of the Esub shore fauna. Sclerochilus schornikovi Athersuch and Horne, 1987 On the exposed shore only found in the Esub sample accounting for 5"7% of the fauna. On the sheltered shore accounted for 0.8% of the Sl and 8.6% of the Ssub fauna. Three complete carapaces recovered from $5 and one right valve from $3. Sclerochilus truncatus (Malcomson, 1886) Not found in the intertidal samples, but accounted for 7.1% of the Esub and Ssub fauna. Also found Sla sample (5.5% of the fauna) from the sheltered shore. Complete carapaces were also recovered from $3 and $5 and two left valves from $4.


509

Genus Hemieytherura Elofson, 1941 Hemicytherura cellulosa (Norman, 1865) This species was not found in any of the sheltered shore samples, but both adults and juveniles were recovered from the Em (3"2% of the fauna) and Esub (21.4%) algal samples from the exposed shore.


Genus Semicytherura Wagner, 1957 Semicytherura nigreseens (Baird, 1938) A species found in the upper intertidal regions of both the sheltered and exposed shore, accounting for 17.6% of the fauna in the Eh pools and 4.5% of the fauna of the Em pools on the exposed shore. A similar pattern was found on the sheltered shore with this species accounting for 4.6% of the Sh and 8.8% of the Sm fauna. This species was absent from the low shore and sublittoral samples and also from the sediment samples.

Semicytherura sella (Sars, 1866) Only found in holdfast of the exposed shore Ela accounting for 3"3% of the fauna. Family Xestoleberidae Sars, 1928 Genus Xestoleberis Sars, 1966 Xestoleberis aurantia (Baird, 1838) A relatively common intertidal species, accounting for 12-9% of the Eh, 0.4% of the Em and 3.7% of the El fauna on the exposed shore and 6-9% of the Sh, 3.5% of the Sm and 0.8% of the S1 fauna on the sheltered shore. All adult females contained eggs. This species was not found in the sediment samples or sublittorally.

Phytal ostracod zonation Figure 2 illustrates the zonation of some of the most abundant phytal ostracod species on the sheltered and exposed sides of Filey Brigg. Callistocythere badia was found only amongst the fine sand in the Eh pools on the exposed shore (figure 2a), and occurred in all three pools sampled. Leptocythere pellueida was found only in MHW pools but occurred on both the sheltered and exposed shores (Eh and Sh). Semicytherura nigrescens (figure 2b) occurred in both the MHW and mid-shore pools on both the sheltered and exposed shore, and a similar pattern was seen in Hirschmannia viridis and Xestoleberis aurantia, although the latter species was also recovered from the MLW pools (figure 2c). The genus Paradoxostoma was an important constituent of intertidal rockpool assemblages on both shores. The numbers of P. hibernicum declined down-shore (figure 2d), accounting for a higher proportion of the fauna at MHW. Both Heterocythereis aIbomaculata (figure2e) and Cythere lutea (figure2f) occurred throughout the intertidal zone on both shores, although they accounted for a greater proportion of the fauna on the sheltered shore and were also found on the sublittoral algae on the sheltered shore. Paradoxostoma variabile (figure 2g) was found throughout the intertidal region on the exposed shore, although it was not an important constituent of the MHW pools, and was also absent from the sublittoral sample. On the sheltered shore this species increased in importance down shore, but was absent from the Laminaria or sublittoral sample. Paradoxostoma ensiforme (figure 2h)

510

S.L. Hull a) Callistocythere badia

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d) Paradoxostoma hibernicum • Exposed [] Sheltered

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The zonation of twelve phytal ostracod species on both the sheltered and exposed shore of Filey Brigg.

occurred at all levels on the sheltered shore and was an important constituent of the low shore pools. This species dominated the fauna of the mid-shore pools on the exposed shore, but was absent from both the M H W shore pools and the sublittoral algae. Two further members of the genus Paradoxostoma were only found in the MLW pools, Laminaria and sublittoral samples: P. bradyi was an important constituent of the exposed shore low pool and Laminaria samples, and a similar pattern was seen on the sheltered shore with this species being an important constituent of the sublittoral assemblage (figure 2i). Paradoxostoma abbreviatum was only found sublittorally on the exposed shore, but did occur in the MLW pools and Laminaria samples from the sheltered shore (figure 2j). Members of the genus Sclerochilus were only found in Laminaria samples and sublittorally. Scleroehilus truncatus was found in both the Laminaria and sublittoral samples on the exposed

Ostracods of Filey Brigg g) Paradoxostoma variabile

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j) Paradoxostoma abbreviatum • Exposed [] Sheltered


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shore but was only found sublittorally on the sheltered shore (figure 2k). Sclerochilus abbreviatus (figure 21) was only found sublittorally, and was an important constituent o f the sheltered shore fauna. A similar pattern was reflected by the distribution of S. schornikovi and S. hicksi. Paradoxostoma robinhoodi, Hemicytherura cellulosa and Sclerochilus gewermuelleri were important constituents of the exposed shore sublittoral assemblages, but did not occur in the sheltered shore sample, and a further two species only occurred in the exposed shore Laminaria faunas, Leptocytherepsammophila and Semicytherura sella. The only species that occurred on the sheltered shore, but not on the exposed shore, was Cuneocythere semipunetata. In terms of species composition there was surprisingly, very little difference between the exposed and sheltered shore faunas. However, there some species were found in greater abundance on the sheltered shore, i.e. Heterocythereis albomaculata (Z2= 12.62, d f = 3 , P = 0 . 0 0 6 ) and Cythere lutea (X2 = 9-62, d f = 3, P = 0.027, whereas Paradoxostoma variabile (Z2 = 22-78, d f = 2,

512

S.L. Hull


P=0.0001) and P. hibernicum (Z2=16"37, df=2, P=0.0001) occurred in higher frequencies on the exposed shore. For the remainder of the species which occurred on both the exposed and sheltered side of the shore, there was no significant difference in frequency, e.g. Xestoleberis aurantia (Z2= 1-21, df=2, P=0.545). Comparison of ostracod assemblage structure The Czekanowski coefficients reflect the overall similarity between the 15 assemblages based upon a qualitative analysis of species presence/absence data, and are presented in table 2. The similarity between the littoral phytal assemblages was generally high (QS>0.500), but there was an overall pattern of decreasing similarity with rockpool height on the shore, e.g. Ela shows greater similarity to Em (QS=0.608) than to Eh (QS =0-421). The sublittoral phytal assemblages, however, show very little similarity to the high shore assemblages (e.g. Sh-Ssub QS =0; Eh to Esub QS =0.105), and Esub shows greatest similarity to Ssub (QS = 0"778). The four sediment assemblages (S1-$4) showed very little similarity to the phytal assemblages or to each other (QS0.44) than to S1-$3 (QS 55% similarity. The two sublittoral samples, (Esub and Ssub), form cluster C that has a very low similarity to the other two clusters (< 12%). The cluster analysis of the sediment assemblages is presented in figure 3b. Two distinct clusters are apparent, cluster D contains S1-$3 (S1 to $2, 71% similarity), and cluster E contains $4 and $5 (> 60% similarity). The two clusters are quite dissimilar < 9% similarity. The results of the Shannon Weiner diversity indices, species richness and evenness for the 15 assemblages are shown in table 3. There was no overall pattern of change in diversity with height on shore, either on the exposed or sheltered shore. In terms of species richness, the S1-$3 assemblages contained only a few species (4 or less), whereas the greatest species richness was found in the Em assemblage (S=13). Although the Em assemblage had the highest richness one species (Paradoxostoma ensiforme), accounted for 45% of the fauna within the assemblage, thus Em had the lowest evenness (E=0.69) found throughout the 15 assemblages. On the exposed shore, Esub had the highest diversity (H'=2.18) and a high evenness value ( E = 0.95), followed by Eh ( H ' = 2.05, E = 0"99). The diversity of the Eh assemblage was significantly higher than that of the Sh assemblage (t = 4.33, d f = 103, P < 0.001). However, on the sheltered shore, the highest diversity was found in the Sm assemblage (H'=2.06), although this was not significantly different from that of the exposed shore (t=2.67, P >0.05). The diversity of the Ssub ( H ' = 1-59) assemblage was not significantly different from that of the Esub assemblage (t = 1-65, P >0.05) despite the difference in H' values. There was no significant correlation between algal sediment content (expressed as grams of sediment per gram of seaweed) and diversity (Spearman rank correlation coefficient, r s = 0" 104, P = 0-1), or between trapped algal sediment content and species richness (rs = 0.415, P > 0-05).

Sh Sm Sl Sla Ssub Eh Em El Ela Esub $1 $2 $3 $4 $5

Table 2.

0.889 --

Sm

0.600 0.700 --

SI

0.375 0.428 0.555 --

Sla

Eh 0.778 0.555 0-600 0-375 0.117 --

Ssub

0.235 0-235 0-421 0.533 --

0.727 0.818 0-583 0.300 0.190 0.545 --

Em 0-600 0.600 0.545 0.556 0.421 0.600 0.667 --

El 0-421 0.632 0-571 0-588 0.444 0.421 0.608 0.762 --

Ela 0.000 0-000 0.381 0-353 0.778 0.105 0.174 0.381 0-400 --

Esub 0.154 0.153 0.267 0.364 0-167 0.154 0.117 0.267 0-286 0-143 --

S1 0.333 0.333 0.286 0.200 0.000 0.333 0.250 0.286 0.307 0.000 0.571 --

$2

0.364 0-364 0.154 0.222 0.200 0.364 0.267 0.307 0.333 0.000 0.333 0.400 --

$3

0-250 0.250 0.111 0.143 0.133 0.250 0.200 0-222 0.235 0.000 0.000 0.000 0.222 --

$4

0.375 0-375 0.222 0.286 0.267 0.375 0.300 0.444 0.470 0-058 0.182 0-222 0.444 0.714

$5

Czekanowski coefficients (QS) representing a qualitative estimate o f faunal affinity between the fifteen assemblages investigated at Filey Brigg (site designations as in table 1).


t.a,a

t~ t~

'-~

514

S.L. Hull 3 a)

SI Ela

i

Sh

Eh Sm

C

Esub

t

Ssub


100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0

% Similarity

3 b)

S1 D

$2 $3

$5

I 100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0

% Similarity F I G . 3.

Dendrograms obtained after cluster analysis of Bray-Curtis similarity coefficients, (a) phytal assemblages and (b) sediment assemblages.

The lowest diversity occurred in the sediments collected from the $2 and $3 sites ( H ' = 0.95 and 0.64 respectively), and although evenness was high (E = 0.87 and 0"93 respectively), very few species were found at these two sites. The highest diversity found within the sediment samples was found in $4 ( H ' = 1.90), which had the same number of species as was found in $5, but a higher evenness. Some species occurred in both the phytal and sediment samples (e.g. Heterocythereis albomaculata and Cythere lutea), however, Palmoconcha laevata, Bythocythere bradyi, Pontocythere elongata and Urocythereis britannica were only found amongst the sediment samples. An overall comparison of the five H' values obtained for the exposed, sheltered and sediment assemblages demonstrated a significant difference in diversity (ANOVA, F2,12 = 5.56, P = 0.02), the exposed shore having higher diversity overall than the sediment assemblages (Tukey, P = 0.05). Discussion In the current study, 32 extant species of ostracod were found at Filey Brigg. Eleven of these species had not been previously recorded for the Yorkshire coast


515


Table 3. Shannon Wiener diversity (H'), Species Richness (S) and Evenness (E) for the ostracod assemblages from 15 sites at Filey Brigg (site designations as in table 1). Site

No. of live individuals, n

Diversity, H'

Richness, S

Evenness, E

Eh Em E1 Ela Esub Sh Sm Sl Sla Ssub S1 $2 $3 $4 $5

85 233 79 27 75 140 65 118 19 14 7 6 5 8 25

2-05 1'78 1.79 1'82 2.18 1"67 2-06 1"92 1-84 1'59 1-15 0-95 0-64 1-90 1-68

9 13 9 8 10 9 10 12 8 8 4 3 2 7 7

0-99 0'69 0.82 0'88 0"95 0'76 0"89 0"77 0"88 0"77 0-83 0"87 0-93 0"98 0-86

(i.e. CaIlistocythere badia, Leptocythere pellucida, L. psammophila, Urocythereis britannica, Sarsicytheridea punctilla, Paradoxostoma hibernicum, Hirschmannia viridis, Bythocythere bradyi, Pontocythere elongata, Sclerochilus abbreviatus, S. schornikovi). A further four species recorded as being broadly distributed around the British Isles (Brady and Norman, 1889) were also present, (i.e. Cytheroisfischeri, Cytherura nigrescens = Semicytherura nigrescens, Cytherura sella = S. sella, Loxoconcha impressa = Loxoconcha rhombiodea). In a study o f the fauna of kelp holdfasts, Moore (1973) recorded the presence of Hemicythere villosa, Cythere albomaculata = Heterocythere albomaculata, and Cythere lutea in samples collected from Filey Brigg, plus a further eleven species (Loxoconcha tamarindus= Palmoconcha laevata, Philomedes interpuncta, Cythermorpha fuscata, Sclerochilus contortus, Paracytherois arcuata, P. flexuosa, Cytherura cellulosa = Hemicytherura cellulosa) at various sites on the north east coast of England. Paradoxostoma variabile, P. abbreviatum, P. bradyi and P. normani were found in Laminaria holdfast samples collected at Robin Hood's Bay (Moore, 1973) and Horne and Whittaker (1985), during a re-evaluation of the taxonomy of the genus Paradoxostorna, recorded a further three species at that site (i.e., P. ensiforme, P. nealei, P. robinhoodi). All seven species listed as occurring at Robin Hood's Bay were also found on Filey Brigg, plus one additional species, P. hibernicum. The taxonomy of Sclerochilus was revised by Athersuch and Horne (1987) who recorded three species from the Yorkshire coast (i.e.S. gewemuelleri and S. hicksi from Robin Hoods Bay, and S. truncatus (juvenile only) from Whitby). All three of these species were also found on Filey Brigg, plus two additional species, Sclerochilus abbreviatus and S. schornikovi. However, Sclerochilus contortus was not found during the current study, but had been previously recorded from Robin Hood's Bay (Moore, 1973). The current study also confirms the presence of Cythere (?) semipunctata = Cuneocythere semipunctata and Xestoleberis aurantia, neither of which had been previously recorded for the Yorkshire coast (Brady and Norman, 1889).


516

S.L. Hull

Ostracod zonation patterns Although some species had an almost ubiquitous distribution (e.g. Cythere lutea, Heterocythereis albomaculata), other species were more limited in their distribution patterns. Wieser (1952) found no relationship between ostracod species and tidal height, and zonation patterns may be masked by other factors (Whatley and Wall, 1975). Home (1982b) examined the zonation of 28 species of ostracod on Corallina at Gore Point, Bristol Channel and found that the distribution of certain species did vary with tidal height. In the current study in which only algal assemblages were examined rather than separate algal species, zonation patterns were also apparent. The species of the genus Paradoxostoma showed some interesting distribution patterns. Paradoxostoma hibernicum declined in number down shore and was not found in the low shore or from sublittoral samples. Paradoxostoma ensiforme occurred at all tidal levels. Paradoxostoma variabile increased in number down shore. Paradoxostoma bradyi was an important constituent of the low shore and Laminaria samples, and P. abbreviatum was found mainly in the sublittoral samples. Paradoxostoma variabile is an important constituent of low shore intertidal assemblages (Home, 1982a, 1982b), but its importance may vary with season (Preston and Moore, 1989). At Filey Brigg, the different species of the genus Paradoxostoma may occupy different niches on the shore at different tidal heights. The Sclerochilus species found at Filey Brigg were only found on the Laminaria samples or sublittorally, therefore the current study agrees with the findings of Athersuch and Horne (1987) who regarded the genus Sclerochilus as containing shallow-water benthonic species. Hirschmannia viridis, Xestoleberis aurantia and Semicytherura nigrescens were only found within the tidal rockpools and occurred in greater numbers higher upshore. These three species are common constituents of the phytal habitat (Hagerman, 1965; Elofson, 1969), and are known to show seasonal patterns in abundance related to their life-cycles (Hagerman, 1968, 1978). All adult female Xestoleberis aurantia contained eggs within their carapaces and are known to breed during the summer months (Hagerman, 1978). Hirschmannia viridis was only represented by juveniles as this species breeds in spring after which the adults die and the juveniles overwinter in the A-7 or A-8 instar (Hagerman, 1969). One species, Callistocythere badia, which was an important constituent of the high-shore rockpools on the exposed shore, did not occur elsewhere. This littoral species appears to be confined to the British Isles where it has a widespread but infrequent distribution (Athersuch et al., 1989) and is regarded by some authors as a Lusitanian/ Mediterranean species (Vork and Thomsen, 1996). Ostracod assemblage structure The 32 species found on Filey Brigg compares well with the number of species found by other workers, i.e. 28 species on Corallina from the Bristol Channel (Home, 1982b), 21 phytal species from three sites in Pembrokeshire (Trier, 1993), 23 species from the Aberystwyth area (Whatley and Wall, 1975), 35 species from various sites (both phytal and sedimentary) on the Isles of Scilly (Neale, 1970) and 14 species from Corallina in W. Norway (Hagerman, 1968). The intertidal phytal assemblages of ostracods had a high degree of similarity (table 2), but the pattern overall was one of decreasing similarity with progression down shore, which is probably is reflection of the zonation of the different constituent species. However, the sublittoral assemblage showed very little similarity with the high-shore assemblage. Five of the eight species found in the Ssub and five of the



517

10 species found in the Esub assemblages did not occur intertidally. This contrasts with the pattern found by Trier (1993) who recorded that only five of 22 species found sublittorally did not occur between the tide marks. Quantitative analysis using the Bray Curtis similarity dendrograms, confirmed that there was considerable clustering attributable to tidal level. The sediment assemblages were rather speciespoor in comparison with the phytal assemblages, with the greatest number of species being found in $4 and $5. Elofson (1940) found 17 species living on mud in Plymouth, and Hagerman (1965) recorded 30 species from a study of 57 benthic samples from various depths in the Oresund. Two of the species found in the sediment samples were also found on algae and sublittorally, i.e. Cythere lutea and Heterocythereis albomaculata. These two species are known to be generalists with broad distributions (Athersuch et at., 1989) and have also been found associated with intertidal Sabellaria reefs (Horne, 1982a). However, some of the species found in the sediments can be regarded as true sediment-dwelling species, e.g. Palmoconcha laevata, Bythocythere bradyi, Pontocythere elongata and Uroeythereis britannica (Elofson, 1969; Athersuch et al., 1989). In terms of species richness and number of individuals, ostracod assemblages are not as diverse as some littoral assemblages, e.g. copepods see Hicks (1980). The sediment ostracod assemblages are generally less diverse than the phytal assemblages, both in terms of number of individuals and species richness. There is no overall pattern in species diversity either with tidal height, or the trapped sediment content of the algae. This may be a consequence of the seasonal changes in number of individuals and species richness resulting from the life cycles of individual species. The exposed and sheltered sides of the shore had very similar ostracod assemblages, although there was some minor differences in species composition. However, there were some quite marked differences in frequency of occurrence between the two sides of the Brigg, for example Heterocythereis albomaculata and Cythere lutea both occurred in higher frequencies on the sheltered shore, and Paradoxostoma variabile and P. hibernicum occurred in higher frequencies on the exposed shore. As previously stated, both H. albomaculata and C. lutea are generalists and are often found in high sediment-content environments, and therefore would not be affected by the higher sediment content of the sheltered shore algae. The genus Paradoxostoma have specialised mouthparts that may be used for feeding on algal sap (Horne and Whittaker, 1985), therefore they may have greater success in less sediment-rich environments.

Comparison of Filey Brigg ostracods with previously reported British assemblages The assemblages on Filey Brigg bear a strong resemblance to those already reported in the literature with a few notable presences and absences of species. There are three species within the genus Aurila Pokorny, 1955, none of which was found at Filey (or Robin Hood's Bay, Scarborough or Selwick's Bay on the north side of Flamborough Head; Hull, unpublished data). Aurila formed an important constituent of the low shore assemblage at Gore Point in the Bristol Channel (Horne, 1982b) and species from this genus have also been recorded from Pembrokeshire (Trier, 1993), Anglesey (Williams, 1969), Isles of Scilly (Neale, 1970), near Aberystwyth (Whatley and Wall, 1975), but not from Norway (Hagerman, 1965, 1968). It appears that Aurila species reach their northern limits on the south coast of Britain (Athersuch et al., 1989), therefore the North Sea may be too cold for these parthenogenetic females.


518

S.L. Hull

The genus Paradoxostoma was well represented at Filey Brigg, with different species being important constituents of littoral and sublittoral phytal assemblages. However, three members of the genus have been recorded on the west and south coasts of Britain but they were not found in the current study, i . e . P , sarniense Brady 1868, P. porlockense Horne and Whittaker 1985 and P. pulchellum Sars 1866. Paradoxostoma sarniense is regarded as a southern species (Athersuch et al., 1989), but P. pulchellum has been reported from Norway (Hagerman, 1968), and its absence from Filey cannot be explained. It is also absent from other sites sampled on the Yorkshire coast (Robin Hood's Bay, Scarborough or Selwick's Bay on the north side of Flamborough Head; Hull, unpublished data). Another genus that is well represented at Filey Brigg, is the shallow water benthonic genus Sclerochitus. Five species were found at there; S. hicksi which had only previously reported from the type locality (Athersuch et al., 1989), S. gewemuelleri, also known from Robin Hood's Bay and S. truncatus previously known on the Yorkshire coast only from one juvenile from Whitby (Athersuch and Horne, 1987). Sclerochilus gewemuelleri has also been reported from the Bristol Channel (Horne, 1982b), and S. abbreviatus from Pembrokeshire (Trier, 1993). The current study extends the knowledge of the distribution of ostracods around the shores of the British Isles, and describes the patterns of zonation down shore and the structure of ostracod assemblages in different tidal habitats. This study provides a basis for continuing research into the dynamics and structure of ostracod assemblages on the North Sea coast of Britain.

Acknowledgements The author would like to thank the Research and Postgraduate School at University College Scarborough for providing funding for the study and also Professor P. G. Moore and Dr J. E. Whittaker for providing helpful comments on an earlier draft of this manuscript.

References ATHERSUCH, J., HORNE, D. J., and WHITTAKER, J. E., 1989, Marine and Brackish Water Ostracods, Synopses of the British Fauna (New Series) No. 43. (Avon: E. J. Brill), 357 pp. ATHERSUCH,J., and HORNE, D. J., 1987, Taxonomy of the genus Sclerochilus Sars (Crustacea: Ostracoda) from British waters with a pictorial key, Zoological Journal of the Linnean Society, 91, 197-222. BRASlER, M. D., 1995, Microfossils (Suffolk: Chapman and Hall), 193 pp. BOOMER, I., WHATLEY~R., and ALADIN, N., 1996, Aral Sea Ostracoda as environmental indicators, Lethaia, 29, 77-85. BRADY, G. S., and NORMAN, A. M., 1889, A monograph of the marine and freshwater ostracoda of the North Atlantic and of North-Western Europe. Section I. Podocopa, The Scientific Transactions of the Royal Dublin Society, 4(Series II), 63-270, pls 8 23. BRADY, G. S., 1868, A monograph of Recent British Ostracoda, Transactions of the Linnean Society of London, 26 (2), 1-495. COLEMAN, J., 1939, On the faunas inhabiting intertidal seaweeds, Journal of the Marine Biological Association of the United Kingdom, 24, 129 183. DOMMASNES, A., 1969, On the fauna of Corallina officinalis in Western Norway, Sarsia, 38, 71-86. ELOFSON,O., 1940, Notes on the Ostracod fauna of Plymouth, Journal of the Marine Biological Association of the United Kingdom, 24, 495-504. ELOFSON, O., 1969, Marine Ostracoda of Sweden, (Jerusalem: Israel Program for Scientific Translations), 156 pp.



519

HAGERMAN,L., 1965, The ostracods of the Oresund, with special reference to the bottom living species, Ophelia, 2, 49-69. HAGERMAN,L., 1968, The ostracod fauna of Coraltina officinalis L. in western Norway, Sarsia, 36, 49-54. HAGERMAN, L., 1969, Environmental factors affecting Hirshmannia viridis (O. F. Muller) (Ostracoda) in shallow brackish water, Ophelia, 7, 79-99. HAGERMAN, L., 1978, The life-cycle of three species of algal-living ostracods from brackish water, Ophelia, 17, 231-237. HICKS, G. F. R., 1980, Structure of phytal harpacticoid copepod assemblages and the influence of habitat complexity and turbidity, Journal of Experimental Marine Biology and Ecology, 44, 157-192. HORn, D. J., 1982a, The ostracod fauna of an intertidal Sabellaria reef at Blue Anchor, Somerset, Estuarine, Coastal and Shelf Science, 15, 671-678. HORNE, D. J., 1982b, The vertical distribution of phytal ostracods in the intertidal zone at Gore Point, Bristol Channel, Journal of Micropalaeontology, 1, 71-84. HORNE, D. J., and WHITTAKER,J. E., 1985, A revision of the genus Paradoxostoma Fischer (Crustacea: Ostracoda) in British waters, Zoological Journal of the Linnean Society, 85, 131-203. JARVIS, S. C., and SEED, R., 1996, The meiofauna of Ascophyllum nodosum (L.) Le Jolis: characterisation of the assemblages associated with two common epiphytes, Journal of Experimental Marine Biology and Ecology, 199, 249-267. LUDWIG, J. A., and REYNOLDS, J. F., 1988, Statistical Ecology." a primer on methods and computing (USA: John Wiley and Sons), pp. 337. MAGURRAN, A. E., 1991, Ecological Diversity and Its Measurement, (Princeton University Press: Chapman and Hall), 179 pp. MOORE, P. G., 1973, The kelp fauna of Northeast Britain. II Multivariate classification: turbidity as an ecological factor, Journal of Experimental Marine Biology and Ecology, 13, 127-163. NEALE, J. W., 1964, Ostracods as Ecological and Palaeoecological Indicators, Stazione Zoologica, Di Napoli Eds. Califano, L., Montalenti, G., Dohrn, P., and Puri, H. S. Napoli, 33, (suppl.), pp. 347-307. NEALE, J. W., 1970, The marine fauna and flora of the Isles of Scilly. Crustacea: Ostracoda, Journal of Natural History, 4, 399-411. PRESTON, A. O., and MOORE, P. G., 1989, Seasonal cycles of abundance of the flora and fauna associated with Cladophora albida (Huds.) Kt~tz in rockpools, Journal of Natural History, 23, 983-1002. TRIER, K., 1993, A preliminary study of the brackish and marine Ostracoda of the Pembrokeshire Coast, S.W. Wales, in K. G. McKenzie and P. J. Jones (eds) Ostracoda in the Earth and Life Sciences (Rotterdam: A. A. Balkema), pp. 571-581. VOR~:, K. A., and THOMSEN,E., 1996, Lusitanian/Mediterrauean ostracods in the Holocene of Denmark: implications for the interpretation of winter temperatures during the postglacial temperature maximum, Holocene, 6, 423-432. WHATLEY, R. C., and WALL, D. R., 1975, The relationship between Ostracoda and algae in littoral and sublittoral marine environments, in F. M. Swain (ed.) Biology and Palaeobiology of Ostracoda. Bulletin of the American PaIeaontology Society, 65, 173-203. WIESER, W., 1952, Investigations on the meiofauna inhabiting seaweeds on rocky coasts: IV Studies on the vertical distribution of the fauna inhabiting seaweeds below the Plymouth laboratory, Journal of the Marine Biological Association of the United Kingdom, 31, 145-174. WILLIAMS, R., 1969, Ecology of the Ostracoda from selected marine intertidal localities on the coast of Anglesey, in J. W. Neale (ed.), The Taxonomy, Morphology and Ecology of Recent Ostracoda, (Edinburgh: Oliver and Boyd), pp. 229 327.

1

Bythocythere bradyi Callistocythere badia Cuneocythere semipunctata Cythere lutea Cytheroisfischeri Hemicythere villosa Hemicytherura cellulosa Heterocythereis albomaculata Hirschmannia viridis Leptocythere pellucida Leptocythere psammophila Loxoconcha rhomboidea Palmoconcha laevata Paradoxostoma abbreviatum Paradoxostroma bradyi Paradoxostoma ensiforme Paradoxostoma hibernicum Paradoxostoma nealei Paradoxostoma normani Paradoxostoma robinhoodi Paradoxostoma variable Pontocythere elongata Sarsicytheridea punctillata Sclerochilus abbreviatus ScleroehiIus gewemuelleri Sclerochilus hicksi Sclerochilus schornikovi Sclerochilus truncatus Semicytherura nigrescens Semicytherura sella Urocythereis britannica Xestoleberis aurantia

Species

S a r s , 1926 (Norman, 1862) (Brady, 1868) (O. F. MOller, 1785) (Sars, 1866) (Sars, 1866) (Norman, 1865) (Baird, 1838) (O. F . M O l l e r , 1 7 8 5 ) (Baird, 1850a) G u i l l a u m e , 1976 (Fischer, 1855) (Norman, 1865) S a r s , 1866 S a r s , 1928 B r a d y , 1868 B r a d y , 1868 Horne and Whittaker, B r a d y , 1868 Horne and Whittaker, (Baird, 1835) (Brady, 1868) (Brady, 1865) Brady and Robertson, D u b o w s k y , 1939 Athersuch and Home, Athersuch and Horne, (Malcomson, 1886) (Baird, 1938) (Sars, 1866) A t h e r s u c h , 1977 (Baird, 1838) 1987 1987

1839

1985

1985

1

1

--

1

4

S1

1

1

3

$2

1

2

$3

3 1

1

--

7 8

1 4 1

11

15

3

12

11 1 2

5

3

--

1

16

10

Eh

1

3

1

$5

--

1

$4

1

11

7 43

111 10 4

3

13 4 -8 13 5

Em

3

2 17

3 1 16 3 3

5

3

27

El

--

1

6

1

-1 -7 --

3

2

2

Ela

--4 7 6 4 5 -. . --

--

-----4 15 ---1 --9 3 ----13

Esub

The Ostracod fauna of Filey Brigg. Figures denote number of individuals per 30 g of dry s e a w e e d f o r t h e p h y t a l s a m p l e s a n d p e r 100 g o f s e d i m e n t f o r t h e s e d i m e n t s a m p l e s ( s i t e d e s i g n a t i o n s a s i n t a b l e 1).

Appendix


. . 9

3

4 20 --

1

31 1

1

54

Sh

. .

--

2

4

4 6 2

6 13

--

15

Sm

--. .

--

--

1

1

--

1

1

1 2

3

--

--

1

18

3 1 ---

3

8

3

1

--

5 17 2 7

17

2

-42

1

Sl ~ Sla

--

--

--

-------

--

--

--

---------

--

----1 --

--

---

Ssub

~"

~

L~ tO