Helminth communities of the lesser sandeel Ammodytes tobianus L. off the west coast of Ireland

The helminth parasites present in 412 lesser sandeels (Ammodytes tobianus) taken from June 1996 to May 1997 from the Aran Islands on the west coast of Ireland were examined. Ten helminth parasite species were recorded, and more than 92% of the sandeels were infected with at least 1 helminth species. Seven of the species were digeneans, including Brachyphallus crenatus, Hemiurus communis, Derogenes varicus, Lecithaster gibbosus, Opechona bacillaris, Cryptocotyle lingua, and Galactosomum lacteum; 2 nematodes, including Hysterothylacium sp. and Contracaecum sp.; and 1 cestode, Scolex pleuronectis. Three of the 7 digenean species were either larvae or immature. Only 2 species, the digeneans G. lacteum and H. communis, had prevalences greater than 50%. The dominant species was G. lacteum, accounting for 67% of all parasites present. The relationship between spawned groups, host length, and season versus the abundance, prevalence, species richness, and the total number of parasites in the infracommunities was investigated. No difference was found between the parasite communities of the 2 spawning races of the host population. Mean abundance and prevalence of the different parasite species showed seasonal variation. Numbers of parasite species and numbers of parasites increased with fish length. The role of A. tobianus as an intermediate host for helminths was assessed; it was determined that most were infectious to birds or mammals, with the majority of the parasite species being autogenic (infectious to fish). The mean number of parasites per fish was nearly a quarter of the value recorded for A. tobianus in the North Sea, where a much higher intensity of infection was recorded.     

Microdistribution within a population ofAcrocnida brachiata (Montagu), (Echinodermata: Ophiuroidea) in Little Killary, west coast of Ireland

Acrocnida brachiata (Montagu), like many other infaunal ophiuroids, has a penchant for gregariousness. In Little Killary, a small embayment on the west coast of Ireland, it colonises an extensive tract of sandy inshore ground (ca 7 m depth), at densities of 150–200 individuals/m². In the course of a two-year study, variation in regular suction-sampling returns prompted a detailed study of the species distribution pattern. Towards this end, 256 contiguous and stratified core samples were taken along a line of transect, in May 1995. These showed randomness with respect to the population at large, but exposed an aggregated distribution for juveniles and adults separately, at different levels within the sediment. Juveniles formed wide, ‘loose’ patches in the surficial deposit, while adults formed smaller, denseer patches deeper within the sediment. It remains to be seen what this approach may expose, when applied in different seasons, or during different phases of the species life cycle.     

The epifaunal communities of Pelvetia canaliculata and Fucus spiralis

The distribution, size and abundance of Pelvetia canaliculata (L.) and Fucus spiralis L. and the epifaunal communities associated with these two high shore fucoid algae have been studied at several contrasting sites in North Wales. Several environmental parameters were measured at each site and correlated with the distribution of the algae and their associated fauna. These weeds, which occur in perhaps the harshest zone of the shore, support exceedingly impoverished epifaunal communities in which the amphipod Hyale nilssoni (Rathke), small littorinids and acarines predominate. This contrasts markedly with the extremely diverse epifaunal communities associated with algae situated lower in the intertidal zone.     

Hydroid epifaunal communities in Arctic coastal waters (Svalbard): effects of substrate characteristics

The knowledge of cryptic epifaunal groups in the Arctic is far from complete mostly due to logistic difficulties. Only recently, advances in sample collection using SCUBA diving techniques have enabled to explore delicate hydroid fauna from shallow waters. This study is the first attempt to examine the relationship between substrate property (such as size of rock, morphological characteristics of algal or bryozoan host) and hydroid community composition and diversity in the Arctic. Samples of substrates for hydroid attachment including rocks, algae, bryozoans and other hydrozoans were collected around the Svalbard. Examination revealed no substrate-specific species. The substrate property did not have a strong influence on hydroid community. Both species composition and richness were not related to colonized rock surface area and to morphological characteristic of algal host. Therefore, results indicate the opportunistic nature of hydroid fauna in terms of substrate preference. However, the presence or absence of hydroids depended on the surface area of rocky substrate. Hydroids were more often present on rocks of larger surface area. Erect hydroids and bryozoans were important attachment surface for stolonal hydroids.     

The biology of the scaldfish, Arnoglossus laterna (Walbaum) on the west coast of Scotland.

The biology of a Scottish population of the small bothid flatfish, Arnoglossus laterna , was studied from January 1975 until September 1976. The data were taken from monthly samples totalling over 500 fish trawled in 18–36 m on a soft mud bottom. Otoliths were used for age determination and a growth curve was constructed which showed that most growth occurs in the first 2–3 years of life. The maximum age recorded was 8+ years. The fish first mature sexually in their second year at a standard length of 6–7 cm and the short spawning season lasts from the late June to August. Fecundity is length-dependent and the relationship could be described by the regression equation: log fecundity = 3·3472 log standard length (mm) -2·1064. The diet consists mainly of decapod crustaceans (particularly crangonid shrimps), polychaetes, mysids and small fish.     

Salinity stratified benthic macrofaunal communities and long-term monitoring along the west coast of Sweden

Benthic macrofauna was quantitatively sampled in 12 coastal areas along the west coast of Sweden in 1971–1976. The Baltic Current creates a halocline at ≈15m depth which acts as a barrier between two differently structured benthic communities, one of which has a wide extension along the coast below the halocline and the other above the halocline. Physical and chemical factors, e.g., variations in salinity and temperature, have a great influence on the faunal structure above the halocline, whereas biological processes are the main determinating factors of the faunal composition in the comparatively more stable environment below the halocline. The sub-halocline community contains significantly more species (60%), a significantly higher mean abundance (4200 compared with 2000 ind. m^?2) and a significantly greater mean biomass (146 compared with 71 g m^?2 wet wt) than that above the halocline. Diversity measured by the Shannon-Wiener formula and its evenness had approximately the same means in both these habitats, 3.3–3.7 and 0.62, respectively.Four of the areas investigated in 1976 were also studied in the 1920's by approximately the same methods. The number of species, abundance, and biomass were significantly greater in the recent samples than in those taken half a century ago. and the community structures differed between the two periods. These differences are attributed to seasonal and natural long-term changes and different methods in processing the samples obtained. It is concluded that the halocline is a habitat divider and creates a vertical discontinuity for benthic communities on the west coast of Sweden.     

Pigment signatures reveal temporal and regional differences in taxonomic phytoplankton composition off the west coast of Ireland

The composition of phytoplankton assemblages in April, 1998in Galway Bay and during a summer phytoplankton bloom occurringsouthwest of Ireland in August, 1998, was characterized by pigmentsmeasured by high-performance liquid chromatography. Pigmentdata reflecting phytoplankton assemblages dominated by diatomsin Galway Bay and dinoflagellates in the southwest of Irelandwere compared to phytoplankton cell counts. Significant relationshipswere found between the fucoxanthin concentrations and the diatomcell numbers (P < 0.0002 r² 0.63) during April, and betweenfucoxanthin (P < 0.0001 r² 0.79), 19'hexanoyloxyfucoxanthin(P < 0.0001 r² 0.77) concentrations and Gyrodinium aureolumcell numbers during the summer bloom.     

Use of drift substrates to characterize marine fungal communities from the west coast of Portugal

This survey reports the occurrence, diversity and similarity of marine fungi associated with five categories of drift substrates (Arundo donax, Phragmites australis, Spartina maritima, "other stems" and driftwood) collected on four sandy beaches of the western coast of Portugal. "Other stems" and driftwood are composite samples with a variety of identified and unidentified pieces of non-woody and woody substrates respectively. Fifty-six taxa were identified, including 38 Ascomycota and 18 anamorphic fungi. Twenty-six taxa were generalists; however several cases of "substrate recurrence" were identified. The very frequent fungi differed among the categories of studied substrates, with the exception of Corollospora maritima, very frequent on four categories. Except for S. maritima, P. australis and driftwood, cases of multiple fungal colonization were rare. S. maritima was the single substrate with five different marine fungi on one sample, as well as with the highest number of very frequent fungi, highest percentage of colonization and average number of fungi per sample. Driftwood presented the highest value of fungal richness (37 taxa) and A. donax the lowest (22 taxa). ANOSIM analysis of similarity showed that all substrates supported different fungal communities with the exception of the pair P. australis/"other stems". The effect of sample size on estimated fungal richness was tested, and the results let us conclude that, although most of the sporadic fungi (<1% occurrence) will be detected only in a very large number of samples, 60 samples of A. donax and "other stems" and 70 samples of all the other substrates may suffice to assess their respective representative marine mycota.     

The importance of predation and competition in organizing the intertidal epifaunal communities of Barnegat Inlet,New Jersey

Summary Community organization was studied by experiment and observation from October 1972–October 1974 in the marine epifaunal assemblages at each end of Barnegat Inlet, New Jersey. The rock jetty at the wave-exposed eastern end of the inlet possesses an intertidal community with the following attributes: (1) a high intertidal zone dominated by the barnacle, Balanus balanoides, but also occupied by the blue mussel, Mytilus edulis, in rock crevices, (2) a mid and low intertidal zone with usually <10% free space and extreme numerical dominance by Mytilus edulis (usually >85% cover) during summer and fall, and (3) almost no intertidal predators or herbivores. The predatory seastar, Asterias forbesi, is abundant subtidally. Controlled removal experiments indicate that in the mid and low intertidal underlying barnacles perish as a consequence of the establishmentof extensive secondary cover by Mytilus, probably because Mytilus outcompetes Balanus through suffocation or starvation. Mytilus transplants demonstrate that the mussels do not survive outside of crevices in the high intertidal, which thus may represent for Balanus a refuge from competition by Mytilus.The pilings on docks at the protected western end of Barnegat Inlet possess an intertidal epifaunal community with the following characteristics: (1) a high intertidal zone that includes Balanus balanoides, a second barnacle, Balanus eburneus, and an herbivorous gastropod, Littorina littorea, (2) a mid and low intertidal zone with usually >40% free space in the summer and fall and the remaining area covered by several abundant species with no extreme dominant, and (3) abundant predators, chiefly the oyster drill, Urosalpinx cinerea, the blue crab, Callinectes sapidus, and a mud crab, Neopanope texana sayi. Asterias forbesi, while abundant subtidally, is also occasionally present on intertidal surfaces. Controlled exclusion of predators by caging several replicate pilings at the western end of the inlet reveals that predation prevents monopolization of mid and low intertidal space by the apparent competitive dominant, Mytilus. Predation appears to be a direct cause of the relatively great temporal and spatial heterogeneity in the mid and low intertidal of these pilings.Thus, although the Barnegat Inlet intertidal system appears to follow closely the patterns of community organization described for several other rocky intertidal coastlines, this organizational pattern is noteworthy because it is repeated here in a far more seasonal environment and with a new cast of interacting competitors and predators. That crabs play an important role as predators is novel for North America, but only perhaps because all previous North American studies have ignored the rocky intertidal zones of quiet, estuarine waters where in Europe predatory crabs are known to be extremely significant.This paper is dedicated to the memory of Robert H. MacArthur     

Seagrass bed patchiness: effects on epifaunal communities in San Diego Bay, USA

Seagrass habitat structure influences epifaunal density, diversity, community composition and survival, but covariation of structural elements at multiple scales (e.g., shoot density or biomass per unit area, patch size, and patch configuration) can confound studies attempting to correlate habitat structure with ecological patterns and processes. In this study, we standardized simulated seagrass shoot density and bed area among artificial seagrass beds in San Diego Bay, California, USA to evaluate the singular effect of seagrass bed configuration (“patchiness”) on the density and diversity of seagrass epifauna. Artificial seagrass beds all were 1 m², but were composed of a single large patch (“continuous” treatment), four smaller patches (“patchy” treatment), or 16 very small patches (“very patchy” treatment). We allowed epifauna to colonize beds for 1 month, and then sampled beds monthly over the next 3 months. Effects of seagrass bed patchiness on total epifaunal density and species-specific densities were highly variable among sampling dates, and there was no general trend for the effects of fragmentation on epifaunal densities to be positive or negative. Epifaunal diversity (measured as Simpson's index of diversity) was highest in very patchy or patchy beds on two out of the three sampling dates. Very patchy beds exhibited the highest dissimilarity in community composition in the first two sampling periods (August and September), but patchy beds exhibited the highest dissimilarity in the third sampling period (October). Our results indicate that seagrass patch configuration affects patterns of epifaunal density, diversity, and community composition in the absence of covarying bed area or structural complexity, and that patchy seagrass beds may be no less valuable as a habitat than are continuous seagrass beds. The spatial pattern employed when harvesting or planting seagrass may influence epifaunal habitat use and should be a key consideration in restoration plans.     

The red-crab bloom off the west coast of Baja California, Mexico

Hydroacoustic data indicate that the benthic red crab Pleuroncodesplanipes(Stimpson, 1860) rises from the bottom towards the surfaceat dusk from very compacted patches settled on the continentalshelf. The behaviour is fast and abrupt, lasting >60 min.     

The genus Eurydice on the west coast of India

An ecological survey of the sandy beaches of the west coast of India revealed an important population of eurydicid isopods ( Eurydice peraticis Jones; E. indicis sp. nov.) of which one species is new to science. The systematics of these isopods are described, and their distribution on the Arabian Sea coast and the Indian beaches is discussed. Differences in their horizontal and vertical distribution on the beaches are explained in relation to the prevailing environmental conditions, of which exposure is the most important.