This study reports on the seasonal variations of the community structure of a coastal ecosystem, off the central coast of Brazil. Samples were collected on a monthly basis on board a bottom otter trawl vessel from October 2003 to September 2004. A total of 57 species belonging to 26 families and 10 orders were collected. Resident species, which presented a high proportion of juveniles throughout the year, were the most abundant. Among these, benthonic fish of the Sciaenidae family were the dominant species, followed by Tetraodontiformes, nektonic Sciaenidae and Clupeiformes. Benthonic fish were more abundant during the spring/summer months (October to February) and pelagic species dominated the autumn/winter months (May to September). However, these differences were not statistically significant. The spring/summer months were also characterized by reproduction activity, while the autumn/winter months saw high proportions of juveniles. Indicator species analyses showed that 5 species presented significant differences in their occurrence and abundance throughout the seasons of the year. This study shows that the coastal area is an important place for reproduction and a nursing ground of many species. It also shows evidence of community-level reproductive patterns for a tropical ecosystem. Future studies are necessary to identify the likely ecosystem forcings underlying these patterns.

The present study aims to evaluate the vertical distribution of intertidal benthic organisms in different periods of the year, relating them to tide, air temperature, height and wave periodicity in breakwaters off the northern Rio de Janeiro State, and to compare the zonation at two sites (Pier and Barra) with distinct hydrodynamics, due to different wave swell. Quadrats of 400 cm2 were sampled by a photoquadrat method. The upper limit of the marine organisms was higher at the Barra site (intertidal zone of 3.8 m) than at the Pier site (intertidal zone of 2.2 m). The littoral fringe assemblage did not show significant differences between sites, but a larger range of this fringe and the upper eulittoral band at Barra was quite evident. This site was mostly characterized by species of more exposed areas such as Chaetomorpha sp. and Perna perna in the upper and lower eulittoral bands, and by C. teedii and Ulva fasciata in the sublittoral fringe. A seasonal difference was identified in the air exposure degree at the Pier site, which was higher in October 2005 and February 2006. The air temperature and wave height and periodicity differed significantly among the four studied periods. The typical seasonal species were F. clenchi (July 2005 and October 2005), Gigartina domingensis (July 2005), Grateloupia sp. (October 2005) and Porphyra acanthophora (October 2005 and February 2006). The intermediate benthic band of the intertidal zone occupied a narrow zone, changing its spatial location according to the season of the year. The hypothesis of annual variation of the benthic community zonation according to the seasonal variability of tides, air temperatures and wave's height and periodicity was accepted for the intermediate band of the intertidal zone, due to the taxonomic differences and the abundance of dominant species in the four seasons. The difference in the vertical distribution of the intertidal benthic assemblages of both breakwaters highlights a distinct wave exposure condition, and reflects the breakwaters' orientation and the wave swell at each site.

Wet biomass of principal plankton components and whole plankton standing stock were assessed in waters of the Heron Island ring reef and surrounding deep lagoon. Biomass of phytoplankton ranged between 30 to 120 mg m−3, without its pronounced depletion over the reef shallows. Picocyanobacteria and prochlorophyte algae contributed over 70% of this biomass. Biomass of bacterioplankton varied between 75 to 340 mg m−3, with its maximum over the reef flat. Biomass of planktonic protozoa's ciliates and zooflagellates ranged between 20 to 110 mg m−3. The daytime biomass of zooplankton varied between 490 to 1590 mg m−3 in the deep lagoon in the zone of intense tidal currents. Over the reef shallows, it was 10–20 mg m−3. At night, it rose there up to 800 to 4000 mg m−3 as the result of emerging demersal zooplankton from the benthic substrates. The time scale of nocturnal emerging by different taxa was also documented. Biomass of whole demersal zooplankton communities hiding by the daytime in bottom substrates at the reef flat was found to be over 100 g m−2. Problems of nutrition planktivore reef fauna related to the plankton production and abundance are discussed.

The distribution of abundance and biomass of prokaryotes, flagellates, ciliates and phytoplankton, were studied in five ponds of increasing salinity in the Sfax solar saltern (Tunisia) coupled with environmental factors. The results showed that abundance of eukaryotic microorganisms decreased with increasing salinity of the ponds whereas prokaryotes (heterotrophic bacteria and Archaea) were abundant in the hyper-saline ponds. Phototrophic picoplankton was found in a large range of salinity values (70 and 200‰). Phototrophic non-flagellated nanoplankton which dominated in the first sampled pond was substituted by phototrophic flagellated nanoplankton in the other ponds. Heterotrophic nanoplankton dominated in the crystallizer pond but its quantitative importance declined in the less saline ponds. Diatoms and dinoflagellates were the major contributors to phytoplankton abundance in the first ponds (>90% of total abundance). Ciliated protozoa were found in all the ponds except in the crystallizer in which prokaryotes proliferated. Oligotrichida and Heterotrichida were the most abundant ciliate groups. Overall, species richness decreased with salinity gradient. We propose a simplified diagram of the Sfax saltern's food web showing the dominant role of the microbial loop along the salinity gradient.

The cryptic invasion of the Asian macroalga Codium fragile (Suringar) Hariot ssp. fragile on north-eastern Atlantic shores has been long considered a classical example of a successful invader that has competitively displaced native congeners. Yet, the lack of quantitative information about morphologically similar native congeners, namely Codium tomentosum Stackhouse and C. vermilara (Olivi) Delle Chiaje, has hindered interspecific comparisons and ecological predictions. From September 2002 to 2005, we made extensive intertidal surveys on 12 northern and 26 southern rocky shores of the English Channel, specifically documenting the abundance, distribution and identity of Codium assemblages. On the north side of the English Channel, the native C. tomentosum and alien C. fragile were both sparsely distributed in intertidal pools in Devon. In contrast, the natives were absent from and the alien was locally abundant in shallow lagoons and rocky reefs around Bembridge and Whitecliff on the Isle of Wight. Finally, in the Channel Islands off the Atlantic coast of France, Codium spp. were abundant in pools and on low-shore emergent substrata with native species predominating. Patterns of distribution varied substantially among Guernsey, Jersey and Alderney, despite their close proximity. The regional variation in the algal distributions merits further investigation to determine whether the pattern is produced by: (1) anthropogenic activities and effects; (2) ecological interactions; (3) oceanographic factors; or (4) some combination of these.

This study shows that the smaller phytoplankton are better able to acclimate to rapid fluctuations in temperature in the open ocean. In contrast, phytoplankton of all sizes have possibly the same ability along the coast.

This paper describes phytoplankton abundance data collected in the Sea of Marmara in 2000 and identifies new species to the region. The quantitative sampling was carried out monthly at 3 stations and seasonally at 6 stations at depths of 0.5, 5, 10 and 20 m. Additionally, vertical samplings by plankton net from 15–0 m were carried out in order to determine the species diversity. Simultaneously measured physical (salinity, temperature and Secchi disc) and chemical parameters (dissolved oxygen, nitrate + nitrite, chlorophyll-a, phosphate and silicate) were evaluated together with phytoplankton data. One hundred and fifteen species were recorded which are members of 55 dinoflagellates, 42 diatoms, 11 silicoflagellates and 7 other groups. Those species include toxic species with high reproduction rates and species that are accepted as carrying risk. Blooms of Anabaena sp., Nitzschia longissima (Brébisson in Kützing) Ralfs in Pritchard and Prorocentrum triestinum Schiller species were observed during the study. Dictyocha antarctica Lohmann 1919, Dictyocha crux Ehrenberg 1840 and Nitzschia rectilonga Takano 1983 species were recorded for the first time from the coastal waters of Turkey. The maximum phytoplankton abundance has been observed during the winter and autumn seasons in the 0.5 and 5 m depths; the concentration of the diatoms was higher during late winter and autumn, however, the concentration of the dinoflagellates was always high during the whole year and they did not show a seasonal variation. The phytoplankton density was lower at the 20 m depths because of the low light penetration property of the Sea of Marmara.

Marine specialist herbivores inhabiting Japanese rocky shores are significantly more diverse than in other biogeographical regions at comparable latitudes. The interaction webs of specialist sacoglossans were investigated on the Pacific shore of Honshu, Japan. The host use of the small stenophagous sacoglossan opisthobranch Placida sp. (sensu Baba, 1986) was investigated in association with the green macroalgae Codium spp. Based on field associations, Placida sp. attacked six congeneric algal host species out of eight investigated (75%) in and around Sagami Bay and ten of 20 species (50%) in Japan. In pairwise-choice feeding experiments, Placida sp. preferred the algal host from which it was collected (source alga) to alternate host and non-host algae. Preference rankings, however, could be altered based on the condition or identity of the choices (e.g. old versus young fronds of C. fragile). Connectance values were lower in these high-diversity assemblages than in their low-diversity counterparts on other temperate shores (but these values may increase with additional study). The sacoglossan occasionally coexisted with two other common sacoglossan species (Elysia trisinuata and E. setoensis) and several other less common ones. However, interspecific feeding interactions appeared minor, with no discernible evidence of interference or exploitation competition. Despite the diverse assemblage of specialist sacoglossans feeding on Codium spp., these Japanese sacoglossans (1) had low niche differentiation, (2) were weak interactors with their hosts, and (3) had negligible intra-guild interactions.

Most known algal toxins act on ion channels either directly or indirectly, resulting in a change in intracellular ion concentrations when administered to targeted cells. The present project developed the working conditions for the use of fluorescent dyes in monitoring changes in membrane potential, intracellular calcium, and intracellular sodium levels in mammalian cell lines. Using these conditions, we were able to demonstrate specific changes in fluorescent signals in response to several purified toxins. We were also able to generate algal extracts which, when administered to the developed fluorimetric assays, were able to elicit different pattern of changes in membrane potential, intracellular calcium, and intracellular sodium levels. The differential pattern of responses induced by the different algal toxins in the three fluorimetric assays serve as a proof of concept for the use of multiplex fluorimetric assays in the laboratory monitoring of algal toxins.

The faunal composition within three mono-specific algal habitats was investigated at Likuri Island, southern Viti Levu, Fiji Islands. Gracilaria maramae was the dominant alga within algal drift mat, seagrass bed, and rocky substrate habitats at the study site. This algal species exhibits two distinctive morphologies depending on whether it is attached or loose-lying. When attached to seagrass blades or rocky substrates, this alga has long straight branches stemming from a single holdfast, while detached individuals develop curled tendrils that re-attach to adjacent substrates. Re-attachment behaviour and high growth rates result in a dense mat of drift algae, which provides a suitable micro-habitat for macro-invertebrates. The sources of algal fragments that contribute to the algal mat appear to be nearby seagrass beds and rocky substrates, where this species may settle directly from spores. Storm events may detach these algae, although pulling experiments showed that the attachment to rocky substrates is 5 times stronger than the attachment to seagrass blades. Results from the macro-faunal samples indicate that the loose-lying algal mat habitat had the highest abundance and biodiversity of organisms, followed by the seagrass bed, and then the rocky substrate habitat. The ability of loose G. maramae fragments to re-attach, along with their high growth rate, may provide a unique micro-habitat for highly abundant and diverse faunal assemblages, which in turn may sustain adjacent near-shore communities. This study highlights the ecological importance of floating algal mats to coastal ecosystems, which should be considered in future management strategies throughout the Fiji Islands.

The overall biotic pressure on a newly introduced species may be less than that experienced within its native range, facilitating invasion. The brown alga Sargassum muticum (Yendo) Fensholt is a conspicuous and successful invasive species originally from Japan and China. We compared S. muticum and native macroalgae with respect to the biotic pressures of mesoherbivore grazing and ectocarpoid fouling. In Strangford Lough, Northern Ireland, S. muticum thalli were as heavily overgrown with seasonal blooms of epiphytic algae as native macroalgal species were. The herbivorous amphipod Dexamine spinosa was much more abundant on S. muticum than on any native macroalga. When cultured with this amphipod, S. muticum lost more tissue than three native macroalgae, Saccharina latissima (Linnaeus) Lane et al., Halidrys siliquosa (Linnaeus) Lyngbye and Fucus serratus Linnaeus. Sargassum muticum cultured with both ectocarpoid fouling and amphipods showed a severe impact, consistent with our previous findings of large declines in the density of S. muticum observed in the field during the peak of fouling. Despite being a recent introduction into the macroalgal community in Strangford Lough, S. muticum appears to be under biotic pressure at least equal to that on native species, suggesting that release from grazing and epiphytism does not contribute to the invasiveness of this species in Strangford Lough.

In the present study, we evaluate the influence of biotic and abiotic factors on temporal fluctuations of Sargassum filipendula in a subtropical shore. Monthly algal samples, abiotic components, amphipod grazer density, and epiphyte biomass were obtained from a Sargassum bed in south-eastern Brazil. Density of S. filipendula fronds decreased during the sampling period, whereas dry mass was more constant, although with a noticeable reduction in the warmer months. Hypnea musciformis was the most frequent epiphyte on S. filipendula, occurring in all sampling periods, although with significant temporal variation. Sargassum filipendula density and dry mass were both influenced by epiphyte dry mass, temperature, and amphipod grazers. Sargassum filipendula biomass negatively influenced total epiphyte biomass, whereas H. musciformis biomass was positively influenced by phosphate, nitrite, and S. filipendula density and negatively influenced by S. filipendula dry mass and amphipod grazer abundance. Algal temporal fluctuations can be related to local abiotic and biotic factors, but the variation observed for S. filipendula and its epiphytes suggest that these factors have quite distinct effects for these algae.

Rafting on floating macroalgae is a common dispersal mechanism of marine benthic invertebrates. Most benthic macroalgae are inhabited by diverse epifaunal communities but not all organisms may be adapted to live on floating algae. In particular, knowledge about the immediate effects of algal detachment on the associated biota is limited. Herein, we studied the composition of the communities of mobile invertebrates on benthic thalli of Ascophyllum nodosum and compared it with detached thalli that had floated for short periods. The community of the mobile invertebrates changed significantly within the first minute after detachment of the algae and showed decreased diversity and a tendency towards reduced abundances in most taxa. However, during the subsequent two hours of floating at the sea surface the species composition did not change further. A comparison of the size-spectra of the gastropod Littorina obtusata from attached and detached algae did not reveal differential migratory activity among size-classes of these gastropods. Most of the species encountered in this study are common rafters in coastal and offshore waters, which are well capable of holding onto floating seaweeds. Therefore, our results indicate that the animals actively abandoned the macroalgae immediately after detachment. A benefit of this behaviour may be to avoid increased predation risk in the open water. The fact that individuals remain associated with their algal host after detachment indicates the importance of rafting dispersal for a great variety of phytal species that might lead to range expansion and regional population persistence through metapopulation effects.

The relatively shallow coldwater coral reefs growing off the eastern coast of Mingulay, north-west Scotland, are excavated by five sponge species, three of which, Alectona millari, Pione vastifica and Cliona lobata, were known previously from Scottish waters. The other two species are new to Scotland and Great Britain. One species is here described as new to science: Cliona caledoniae sp. nov. The species shows a superficial resemblance in colour (orange) and spiculation (possession of tylostyles and knobby microscleres) to Cliothosa hancocki described disjunctly from the Pacific Ocean and the Mediterranean Sea, but it differs clearly in lacking the characteristic Cliothosa amphiasters with branching rays. The Scottish species only possesses peculiar thick-rayed streptasters, which at first glance appear rather similar to the second microsclere type reported for Cliothosa hancocki, knobby-rayed amphiasters. However, the majority of the microscleres in the Mingulay species appear to be genuine spirasters (not amphiasters), and exhaustive search for true amphiasters, branching or otherwise, was in vain. The new species is extensively illustrated. Furthermore, we also report the first occurrence in British waters of Spiroxya levispira, originally described from Azorean deep waters, and subsequently reported from Madeira and several Mediterranean localities. It was found to occur not uncommonly in the Mingulay reefs, and additionally also in reefs of the Rockall Bank, west of Ireland. The spicular characters generally match those of the southern locations. The newly recorded species is described and amply illustrated.

A new free-living marine nematode species, Oncholaimus moanae sp. nov., is described from intertidal fine sand in southern New Zealand. Oncholaimus moanae sp. nov. can be distinguished from other species of the genus by the presence of a pre-cloacal papilla bearing four pairs of short, stout spines, a post-cloacal papilla, long (>70 μm) spicules, and a demanian system with two openings situated laterally at level of uvette. The δ13C signature of O. moanae sp. nov. suggests that benthic microalgae are the main carbon source for this species, but an elevated δ15N signature suggests predatory feeding habits. The fatty acid composition of O. moanae sp. nov. is rich in highly unsaturated fatty acids, which are likely to originate from heterotrophic protists (e.g. ciliates). The data obtained in this study suggest, for the first time, that marine nematodes can be a high quality food source (i.e. rich in highly unsaturated fatty acids) to predators. Large nematodes living near or at the sediment surface, in particular, may represent an important trophic link between heterotrophic protists and higher trophic levels in marine sediments.

Recently developed methods allow quantification and examination of point patterns. Understanding patterns of aggregation or regularity of larval recruits at various spatial scales can help in identifying underlying ecological and biological processes determining their distribution. A rocky shore plot (30 cm wide × 100 cm tall) in southern Hokkaido, Japan was cleared each summer. Barnacle (Chthamallus challengeri) recruitment, after a period of approximately 134 days, was recorded using 40 photographs (25 cm2); 8 photographs per 20 cm horizontal band of tidal height, 5 bands total. Barnacle recruits within each photograph were mapped and co-ordinates used to analyse aggregation at scales from 0–2 cm using Ripley's K statistic and neighbourhood density function (NDF) (both models assumed heterogeneity of first-order density). Quadrat density counts at scales from 20–50 cm provided estimates of aggregation using Morisita's standardized index. These analyses showed that barnacle recruits demonstrate ordered spacing up to a distance of 6 mm. From 6 mm to 2 cm recruits show random spacing based on NDF, but ordered distribution based on the Ripley's K statistic. This discrepancy is likely a result of the cumulative nature of the Ripley's K statistic. At larger scales, Morisita's standardized index indicated aggregation. This result may be explained biologically by the trade off between maximizing need for space at small spatial scales, however being constrained by copulation with neighbours, resulting in aggregation at scales larger than the maximum penis length. The observed pattern was consistent among years with different recruitment densities and among tidal levels, indicating site specific characteristics and interspecific interactions may have a larger influence than desiccation stress or density dependence on spacing of recruits.

The seasonal dynamics of Acartia tonsa and the invader Eurytemora americana were analysed in relation to the environmental variability occurring from April to November in the Bahía Blanca Estuary. Twice a month, the abundance of eggs, nauplii, copepodites and adults was examined and some environmental variables were recorded. Multivariate statistics (CCA) was applied to analyse the data of variables. Acartia tonsa eggs and nauplii diminished from April–May and they were almost absent between June and September, although a small larval peak could be detected from the end of July to October. All the stages of this species increased in number through spring. Eurytemora americana was registered as from June and only nauplii larvae were observed, with a peak increase during September. Copepodites and adults were observed as from July, increasing in number until peaking at the end of September. The number of all stages of this species decreased abruptly, the whole population disappearing from the plankton. The A. tonsa developmental stages were most positively correlated with temperature, photoperiod and other light variables whereas those of E. americana showed positive correlations with chlorophyll-a and salinity. The gradients of the main environmental factors likely give rise to a certain niche separation facilitating the coexistence of the two copepod populations within the period studied.

Epibiotic interactions between macroalgae and crustaceans have rarely been described. We examined the interaction between the mole crab, Emerita analoga and the opportunistic algae Enteromopha spp. in a sandy beach of the central coast of Peru. Enteromorpha spp. was found fouling the carapace of the mole crab that provides the only stable substrate to spore settlement in the beach environment. Epibiosis prevalence was up to 2.1%, and affected mainly larger, ovigerous females. Prevalence presented a seasonal pattern, with peaks during summer. Mole crab body condition was higher when fouled, whereas fecundity was not affected. Fouled mole crabs burrowed at lower speed, which was reversible by the removal of epibiotic algae. The burrowing depth was not affected by epibiosis. Contrary to the expected, the effects of algal epibiosis on demographic and life history parameters of mole crabs, with the exception of body condition, were mainly neutral but important on behavioural traits.

In this study, four species of fiddler crabs (Uca) at Inhaca Island, Mozambique, were studied: their fecundity determined and egg loss between the first and last embryonic development stage evaluated. Ovigerous female crabs were collected throughout February to March (wet season) of 2006, during day-time at low tide, in Ponta Rasa (U. annulipes and U. inversa) and Saco (U. chlorophthalmus and U. vocans) mangroves. Average brood size increased significantly with female and species size, ranging from 932 (CW = 8.51 mm) in U. annulipes, to 18,057 (CW = 23.5 mm) in U. vocans. The number of embryos decreased significantly over the incubation period for each species. Brood loss from embryonic stage I to stage IV for U. annulipes, U. inversa, U. chlorophthalmus and U. vocans was 12.3%, 14%, 43.2% and 23.6%, respectively (P < 0.05). Positive allometry was recorded for all species in the early development stage, however, due to the higher relative brood loss in larger females (U. vocans), when comparing the number of embryos in late developmental stage, a negative allometry was possible to observe. The average volume of embryos at the same stage differed among species although significant differences were found between embryonic stages for all species. Embryo volume increased 96.1%, 93.3%, 92.9% and 96.3% in, respectively, U. annulipes, U. inversa, U. chlorophthalmus and U. vocans (P < 0.05). Differences in brood loss were attributed to habitat substrate and structure, stress factors and behavioural aspects.

A dichotomous identification key for brachyuran zoeal stages from Peter the Great Bay (Russian waters of the Sea of Japan) is provided for the first time. The key covers 16 taxa identified to species level and uses only the most conspicuous external characters of larvae that are easy to observe under a stereomicroscope without specimens dissection. The key is based on the accounts by various authors and new original descriptions of larvae obtained both from plankton samples and from laboratory culture. Brief descriptions of larvae of 16 brachyuran species are also included.