The strength of the North Atlantic Current (NAC) (based on sea-surface elevation slopes derived from altimeter data) is correlated with westerly winds (based on North Atlantic Oscillation [NAO] Index data over a nine year period [1992–2002] with 108 monthly values). The data time window includes the major change in climate forcing over the last 100 years (1995 to 1996). It is shown that the NAO Index can be used for early warning of system failure for the NAC. The correlation response or early warning time scale for western Europe and south England is six months. The decay scale for the NAC and Subtropical Gyre circulation is estimated as three years. Longer period altimeter elevation/circulation changes are discussed. The sea-surface temperature (SST) response of the North Sea to negative and positive NAO conditions is examined. The overall temperature response for the central North Sea to NAO index forcing, reflecting wind induced inflow, shelf circulation and local climate forcing, is ∼5 months. In years with strong North Atlantic winter wind induced inflow, under marked NAO positive conditions, mean temperatures (∼10.5°C) are about 1°C warmer than under negative conditions. In 1996 under extreme negative winter NAO conditions, the North Sea circulation stopped, conditions near the Dogger Bank became more continentally influenced and the winter (March) temperature fell to 3.1°C whereas in 1995 under NAO positive winter conditions the minimum temperature was 6.4°C (February). Seasonal advance of North Atlantic and North Sea temperature is derived in relation to temperature change. Temperature change and monthly NAO Index are discussed with respect to phytoplankton blooms, chlorophyll-a measurements, ocean colour data and the anomalous north-eastern Atlantic 2002 spring/summer bloom SeaWiFS chlorophyll concentrations.

for many decades, scientists at the marine biological association (mba) in plymouth and the centre for environment, fisheries and aquaculture science (cefas), formerly the directorate of fisheries research, at lowestoft have undertaken considerable research into the ecology and life histories of elasmobranch fish around the british isles.

This review provides insights into the distribution and impact of oestrogens and xeno-oestrogens in the aquatic environment and highlights some significant knowledge gaps in our understanding of endocrine disrupting chemicals. Key areas of uncertainty in the assessment of risk include the role of estuarine sediments in mediating the fate and bioavailability of environmental (xeno)oestrogens (notably their transfer to benthic organisms and estuarine food chains), together with evidence for endocrine disruption in invertebrate populations.

Emphasis is placed on using published information to interpret the behaviour and effects of a small number of ‘model compounds’ thought to contribute to oestrogenic effects in nature; namely, the natural steroid 17β-oestradiol (E2) and the synthetic hormone 17α-ethinyloestradiol (EE2), together with the alkylphenols octyl- and nonyl-phenol (OP, NP) as oestrogen mimics. Individual sections of the review are devoted to sources and concentrations of (xeno)oestrogens in waterways, sediment partitioning and persistence, bioaccumulation rates and routes, assays and biomarkers of oestrogenicity, and, finally, a synopsis of reproductive and ecological effects in aquatic species.

Microzooplankton community composition, abundance, biomass and grazing impact were assessed, along with measurements of ciliate growth and mortality, during the onset of the spring bloom in the north-east Atlantic. The study was undertaken as part of the UK Biogeochemical Ocean Flux Study during 1 May to 15 June 1990. The microzooplankton community was composed of protozoans and metazoan developmental stages with respective mixed-layer depth integrated biomass values ranging from 127 to 638 and 74 to 394 mg C m−2. High numbers of aloricate ciliates (up to 35,000 cells l−1) dominated the microzooplankton community during early May prior to the onset of the spring bloom. Ciliate abundance then declined rapidly during mid-May with community growth rates ranging from −0·71 to 0·23 d−1. High abundances of metazoplankton (up to 400 l−1) were also recorded at this time and may have contributed to the decline in ciliate numbers. In late May and early June the protozoan community comprised a more even mix of dinoflagellates, tintinnids and aloricate ciliates. Phytoplankton mortality rates, measured using a dilution technique, ranged from 0·2 to 0·5 d−1. The microzooplankton consumed 8 to 44 μg C l−1 d−1, equivalent to between 16 and 40% of the chlorophyll biomass and 38 and 154% of primary production. These high rates of herbivory reflect the predominance of small (<5 μm in length) phytoplankton cells present throughout the first half of the study and support previous studies demonstrating the microzooplankton to be the main grazers of phytoplankton in the north-east Atlantic. However, there is also evidence that a disparity between predator and prey may have prevented a response by the microzooplankton to rapid increases in phytoplankton biomass and production during the spring bloom.

This special issue of JMBA papers on the gelatinous plankton is dedicated to Sir Frederick Russell, Director of the Plymouth Laboratory of the Marine Biological Association from 1945 to 1965 and pioneer in the study of gelatinous plankton.

Benthic macroinvertebrates were sampled seasonally in the subtidal and upper and lower swash zones at two sites in each of six nearshore habitat types on the lower west coast of Australia. The habitat types, which differed mainly in the extent of their exposure to wave activity and whether sea grass and/or nearshore reefs were present, had been distinguished quantitatively using values for a suite of seven statistically-selected enduring environmental characteristics (Valesini et al., 2003). The core samples yielded 121 species representing eight phyla, among which the Polychaeta, Malacostraca and Bivalvia were the most speciose classes, contributing ∼38, 23 and 10%, respectively, to the total number of individuals. The total number of species and mean density of macroinvertebrates at the most protected habitat type (1), i.e. 70 and 209·2 individuals 0·1 m−2, respectively, were far greater than in any other habitat type. Habitat type influenced species composition to a greater extent than either zone or season. Furthermore, the extents of the differences among the species compositions of the six habitat types statistically matched the extents of the differences among the values for the suite of enduring environmental characteristics that distinguished each of those habitat types. Overall, the species composition at habitat type 1 was the most distinct, containing five abundant species of polychaetes that were adapted to deposit-feeding in calm waters with high levels of organic material and which were rare in all other habitat types. In contrast, the fauna at the most exposed habitat type was characterized by four crustacean species and a species of bivalve and polychaete, whose mobility and tough external surface facilitated their survival and feeding in turbulent waters. The zonal differences in faunal compositions among habitat types were greatest in the case of the subtidal zone. The faunal compositions differed among zones and seasons only at the most protected habitat type.

Jellyfish medusae prey on zooplankton and may impact fish recruitment both directly (top-down control) and indirectly (through competition). Abundances of Aurelia aurita, Cyanea lamarckii and Cyanea capillata medusae (Scyphozoa) in the North Sea appear to be linked to large-scale inter-annual climatic change, as quantified by the North Atlantic Oscillation Index (NAOI), the Barents Sea-Ice Index (BSII) and changes in the latitude of the Gulf Stream North Wall (GSNW). Hydroclimatic forcing may thus be an important factor influencing the abundance of gelatinous zooplankton and may modulate the scale of any ecosystem impact of jellyfish. The population responses are probably also affected by local variability in the environment manifested in intra-annual changes in temperature, salinity, current strength/direction and prey abundance. Aurelia aurita and C. lamarckii in the north-west and south-east North Sea exhibited contrasting relationships to change in the NAOI and BSII: north of Scotland, where the North Sea borders the Atlantic, positive relationships were evident between the abundance of scyphomedusae (data from 1974 to 1986, except 1975) and the indices; whereas west of northern Denmark, a region much less affected by Atlantic inflow, negative relationships were found (data from 1973 to 1983, except 1974). Weaker negative relationships with the NAOI were also found in an intermediate region, east of Scotland, for the abundance of A. aurita and C. capillata medusae (1971 to 1982). East of Shetland, the abundance of jellyfish was not correlated directly with the NAOI but, in contrast to all other regions, the abundances of A. aurita and C. lamarckii (1971 to 1986, not 1984) were found to correlate negatively with changes in the GSNW, which itself was significantly positively correlated to the NAOI with a two year lag. On this evidence, we suggest that, for jellyfish, there exist three regions of the North Sea with distinct environmental processes governing species abundance: one north of Scotland, another east of Shetland, and a more southerly group (i.e. east of Scotland and west of northern Denmark). Impacts by jellyfish are likely to vary regionally, and ecosystem management may benefit from considering this spatial variability.

The benthic system of the Golfo San Jorge was characterized from physico-chemical parameters based on samplings obtained during seasonal research cruises carried out on board the INIDEP vessels from springtime 1999 through wintertime 2000. Spatial and seasonal variations of temperature, salinity, density, oxygen content and chlorophyll-a in bottom water and concentration of total organic matter, total organic carbon, total nitrogen, chlorophyll-a and phaeopigments in sediments were analysed. The origin and nutritional value of the deposited organic matter were also assessed. The behaviour of the physico-chemical characteristics of the benthic habitat, studied applying statistical techniques, defined three sectors with particular characteristics and minimum seasonal variations: sector 1, the largest and deepest one, comprises the central area of the gulf and corresponds to a depositional environment; sector 2 comprises the areas next to the extremes of the gulf and corresponds to a flow or erosive environment; sector 3 includes the coastal area and south-east part of the gulf and belongs to a transitional environment.

elasmobranch fish are susceptible to over-exploitation by commercial and recreational fisheries and an increasing focus of conservation initiatives. the lack of accurate species-specific landings data in many european fisheries and the paucity of biological data have restricted the types of stock assessment that can be undertaken. hence, other methods of determining the overall status of elasmobranch fish are required. for demersal elasmobranchs around the british isles, the most widely available biological data describe life histories and abundance from fishery-independent surveys. here, we examine the length-distribution of demersal elasmobranchs caught during groundfish surveys, to determine which life history stages are sampled effectively. for these stages, we report trends in abundance and relate the trends to knowledge of the species' biology and fisheries, and to the decline criteria that are used to assess species' status by nature conservation agencies. the analyses show that many large demersal elasmobranchs have been severely depleted in uk waters but that groundfish surveys still provide a good source of data for monitoring changes in status of the more abundant species. for rare and highly depleted species, groundfish surveys often provide good retrospective descriptions of declines, but the surveys have limited power to detect recent changes in status.

Zooplankton and hydrography of the upper 200 m was studied in coastal and pelagic waters off central Greece (eastern Mediterranean) during July 1998. The spatial distribution of the main environmental (temperature, salinity, fluorescence) and zooplankton (abundance, dry-weight, dominant groups) features of the area was delimited over an intense grid of 124 stations. The complex topography of the surveyed area comprised an interesting field for the study of pelagic–coastal interaction and its influence on the taxonomic composition of zooplankton.

A typical summer thermal stratification was observed over the entire study area. Marked differences were found in surface-salinity between the eastern (Aegean Sea) and the western (Ionian Sea) part of the study area, which was attributed to the presence of less saline waters originating from the Black Sea. A deep fluorescence maximum was present in both coastal and pelagic stations. Zooplankton abundance and biomass showed an inshore–offshore gradient with coastal areas being significantly richer than pelagic areas. The taxonomic composition of zooplankton varied greatly both along the inshore–offshore gradient and among the different semi-enclosed Gulfs. Copepods were the dominant group in the pelagic waters comprising 67–78% in terms of mean relative abundance. In coastal areas, copepods were less important with cladocerans (especially the species Penilia avirostris) being the dominant group (44–51%). Appendicularians and chaetognaths comprised an important component of the zooplankton community over the entire surveyed area with mean relative abundance ranging from 2·5 to 14% and 0·6 to 5·8%, respectively.

The concentrations of booster compounds were surveyed in the port of Osaka, Japan. The concentrations of Sea-Nine 211, Diuron and Irgarol 1051 in water samples from the port of Osaka were in the ranges <0·30–0·55 ng l−1, 13–350 ng l−1, 1·3–77 ng l−1, respectively. Pyrithiones were not detected in water samples. The levels of Diuron and Irgarol 1051 in the port of Osaka were high in the mooring area for small and medium-hull vessels with poor flushing.

Susceptibility of bacterial populations in estuarine water to antifouling biocides was studied. Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione dissolved in dimethyl sulfoxide (DMSO) were added to estuarine water and number of colony forming units (CFU) of bacteria in estuarine water was counted using R2A agar plate. The CFU was not decreased at the concentration less than 1·0 mg/l of Diuron, Irgarol 1051 and Copper pyrithione. However, CFU was decreased at 0·1 mg/l of Sea-Nine 211. Degradation of Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione by bacteria in estuarine water was studied using a die-away method. At an initial concentrations of 0·1 mg/l, observed half-lives of Sea-Nine 211 and Copper pyrithione were 10 and 20 days, respectively. In contrast, Diuron and Irgarol 1051 were degraded scarcely during 60 days of culture.

Photodegradation of these booster biocides by sunlight and UV light were studied. Under UV, all biocides were below detection limit after one day of irradiation. Under sunlight, Copper pyrithiones were also below detection limits after one day. Drastic decrease of Sea-Nine 211 concentration was observed after one day. Diuron and Irgarol 1051 scarcely decreased during 17 days of sunlight irradiation.

A quantitative study of macrobenthos was carried out on three transects on the shelf and continental slope off Chile (22° to 42°S; from 100 to 2000 m water depth) within and beneath the oxygen minimum zone (OMZ). Macrobenthos mean densities ranged from 104 to 13 808 ind m−2, with highest values off Concepción (∼36°S), where highest chloroplastic pigment equivalents were also measured. Polychaetes were the numerically dominant group in all transects and depths, followed by peracarid crustaceans. Species richness and diversity correlated with observed changes in bottom-water oxygen concentrations and sediment-bound pigments. Our results show that the shelf macrobenthic communities were negatively affected by low oxygen. The non-metric multidimensional scaling (nMDS) analysis evidenced depth-related station groups which may be related to the different environments provided by the water masses involved. Indeed, the depth ranges of stations groups with their specific species inventories coincide quite well with the boundaries of the three important water masses in the region, the Equatorial Subsurface Water (∼50 m to ∼400 m depth), the Antarctic Intermediate Water (∼400 to ∼1200 m depth), and the Pacific Deep Water (>1200 m depth).

published data on the diversity, life history, ecology, and status of freshwater and euryhaline elasmobranchs was reviewed in the context of anthropogenic threats and principles of conservation biology. at least 171 species of elasmobranch, representing 68 genera and 34 families, are recorded from fresh or estuarine waters. of these, over half are marginal in estuaries, less than one-tenth are euryhaline, and one-fifth are obligate in fresh water. obligate freshwater elasmobranchs are dominated by myliobatoid stingrays, of which two-thirds are potamotrygonids endemic to atlantic drainages of south america. freshwater and euryhaline elasmobranchs adhere to strongly k-selected life histories and feed at high trophic levels, similar to those of their marine relatives. however, freshwater and euryhaline elasmobranchs are also subject to habitat constraints, notably more limited volume and physicochemical variability than the ocean, that may render them more vulnerable than marine elasmobranchs to the effects of human activities. the greatest diversity and abundance of freshwater and euryhaline elasmobranchs occur in tropical countries with enormous and rapidly increasing human populations, notably south america, west africa, and south-east asia. knowledge of the biology, distribution, ecology, and status of freshwater and euryhaline elasmobranchs is frustrated by unresolved taxonomic problems, which are briefly summarized. to clarify selected issues in the conservation of freshwater and euryhaline elasmobranchs, special attention is given to sharks of the genus glyphis, pristids, and potamotrygonids. to foster live release when possible as well as prevent discard of specimens and loss of data, an illustrated key to differentiate carcharhinus from glyphis sharks is provided. obligate freshwater elasmobranchs with limited geographic ranges are deemed most vulnerable to extinction, but euryhaline elasmobranchs that require access to the sea to breed are also at significant risk. based on the foregoing data and principles of conservation biology, suggested action plans for the conservation of freshwater and euryhaline elasmobranchs and the conservation of freshwater habitats are provided.

Regular sea temperature measurements have been made since 1975 at Gravelines (French coast of the Southern Bight of the North Sea) within the framework of a research programme aimed at monitoring the influence of the thermal discharge of a nuclear power plant. The sampling has yielded a 28-year time-series. Pluriannual natural fluctuations of temperature show cyclic patterns and long-term trends in good accordance with global climatic changes as revealed by the NAO (North Atlantic Oscillation) annual index.

Mesozooplankton distribution was investigated over an intensive grid of 124 stations in coastal and pelagic waters of central Greece (eastern Mediterranean) during July 1998. The complex topography of the area consisted of various semi-enclosed gulfs as well as open-sea areas and provided excellent fieldwork for determining species assemblages, their relationships to environmental parameters and the distribution and abundance patterns of the copepod species.

Three coastal and one pelagic group of stations were revealed by cluster analysis. Inverse analysis of species affinities defined distinct ‘coastal’ and ‘pelagic’ species assemblages. All coastal areas were dominated by a small number of species (e.g. Penilia avirostris, Podon spp., Ctenocalanus vanus, Paracalanus parvus and Centropages typicus) all belonging to the ‘coastal’ assemblage. Differences among these coastal areas were mainly due to small changes in relative abundance of a common-species list. On the contrary, pelagic stations were characterized by higher species diversity, low dominance and the presence of characteristic epipelagic and mesopelagic species of the Mediterranean Sea (e.g. Calocalanus spp., Haloptilus longicornis, Lucicutia flavicornis, Mecynocera clausi, Farranula rostrata, Mesocalanus tenuicornis and Oncaea mediterranea).

The observed differences in taxonomic composition and abundance of zooplankton were related to the marked differences in salinity values observed between the eastern and western part of the surveyed area. Bathymetry, temperature and fluorescence were also related with the inshore–offshore gradient of the zooplankton community observed in the pelagic areas as well as with the discrimination of the zooplankton communities of the various semi-enclosed gulfs of the region.

Fish assemblages associated with shallow (4–7 m deep) artificial rocky habitats (i.e. breakwaters) have been assessed between July 2002 and September 2003, at the marine protected area of Miramare and adjacent areas outside the reserve (northern Adriatic sea). Our purpose was to: (1) detect possible differences between ‘protected vs fished’ breakwaters; and (2) compare two visual-census techniques for fish assessment (i.e. strip transects vs stationary points). The fish assemblages observed between protected and fished breakwaters during all four sampling periods were statistically different. More fish taxa were found at the protected than fished breakwaters, while there was no difference in total fish density. Most fish species targeted by fisheries had a greater density (e.g. Sciaena umbra, Dicentrarchus labrax, Sparus aurata, Diplodus vulgaris, Diplodus sargus and Diplodus puntazzo) and/or size (e.g. S. aurata and D. annularis) at the protected than fished breakwaters. There was a significant difference in fish assemblages due to assessment method. In general, the number of taxa was greater when assessed by strip transects than stationary points. Total fish density was almost unaffected by the method used, while total density of demersal fish (i.e. excluding schooling species) tended to be greater when evaluated by strip transects, although the difference was statistically significant only in one sampling period out of four. These results indicate that protection from fishing may have the potential to influence fish assemblages associated with breakwaters. Additionally, caution should be used when comparing fish assemblage data collected by different visual assessment techniques.

An historical data set, collected in 1958 by Southward and Crisp, was used as a baseline for detecting change in the abundances of species in the rocky intertidal of Ireland. In 2003, the abundances of each of 27 species was assessed using the same methodologies (ACFOR [which stands for the categories: abundant, common, frequent, occasional and rare] abundance scales) at 63 shores examined in the historical study. Comparison of the ACFOR data over a 45-year period, between the historical survey and re-survey, showed statistically significant changes in the abundances of 12 of the 27 species examined. Two species (one classed as northern and one introduced) increased significantly in abundance while ten species (five classed as northern, one classed as southern and four broadly distributed) decreased in abundance. The possible reasons for the changes in species abundances were assessed not only in the context of anthropogenic effects, such as climate change and commercial exploitation, but also of operator error. The error or differences recorded among operators (i.e. research scientists) when assessing species abundance using ACFOR categories was quantified on four shores. Significant change detected in three of the 12 species fell within the margin of operator error. This effect of operator may have also contributed to the results of no change in the other 15 species between the two census periods. It was not possible to determine the effect of operator on our results, which can increase the occurrence of a false positive (Type 1) or of a false negative (Type 2) outcome.

Analysis of the biological time series of plankton samples collected by the Continuous Plankton Recorder (CPR) in the North Atlantic and North Sea has shown a regime shift in the plankton in this region. Both the distributions of planktonic organisms and their timing of occurrence in the seasonal cycle have changed and these changes appear to reflect global warming. In the North Sea the planktonic larvae of echinoderms have shown a recent dramatic increase in both relative and absolute abundance and their seasonal peak of occurrence has advanced by 47 days. The identity of the echinoderm larvae involved in this change has, however, remained equivocal. The small size of many organisms like echinoderm larvae combined with incomplete taxonomic keys hinders their visual identification and their fragility often means that useful morphological features are damaged during sampling by the CPR. Here, using new molecular methods applied to CPR samples, we show that planktonic larvae of the benthic Echinocardium cordatum dominate the North Sea plankton. We argue that since this species benefits from mild winters and warmer waters their numerical increase in the plankton is consistent with recent climatic changes that appear to be affecting the wider ecology of this region.

Thirty species of sponges (29 Demospongiae, 1 Hexactinellida) have been recorded in association with a white coral bank situated off Cape S. Maria di Leuca (southern Italy) at depths ranging from 430 to 1160 metres. Notwithstanding the occurrence of clearly eurybathic species, two depth-dependent sponge groups can be identified along the bathymetric gradient. Two species, Geodia nodastrella and Plocamiopsis signata, are reported for the first time from the Mediterranean Sea. The sponge assemblage shows a higher affinity with the fauna from the Boreal region, with very low number of Mediterranean endemic species. Systematic notes concerning the poorly known and intriguing species, studied using scanning electron microscopy analysis, are reported.

The unicellular sporophyte phase of the filamentous green alga, Acrosiphonia (Codiolales), is endophytic in the bladed red alga, Mazzaella splendens in southern British Columbia, Canada. Since endophyte maturity coincides with decreased host abundance (winter storms dislodge Mazzaella blades), many endophytes lose their host before zoospore release has occurred. We investigated whether the endophytes can reach reproductive maturity within decaying host tissue (drift blades) or as free-living entities once their host has disappeared. We demonstrate that both occur. Suspension of M. splendens blades, colonized by the endophyte phase of Acrosiphonia, in seawater tanks in winter, resulted in the germination and growth of filamentous Acrosiphonia plants (gametophytes) in spring. Net primary productivity of 132·2 g dry wt/m2/mo was estimated by harvesting total Acrosiphonia biomass after a one-month growing season. An estimate of Acrosiphonia survivorship from zoospore to macroscopic adult gametophyte (0·01–0·89%), is in close approximation with kelp spore survivorship to microscopic gametophyte (0·005–0·1%), but is 102–105 times higher than kelp survivorship from spore to macroscopic adult sporophyte. Differential survivorship in the field and in experimental tanks and among different study sites can be explained by variable mortality factors for spores and germlings and Acrosiphonia's success in colonizing highly disturbed environments.