Megafauna from the Charlie–Gibbs Fracture Zone (northern Mid-Atlantic Ridge) based on video observations from submersibles was analysed. Species composition was examined, frequency of species occurrence on the fracture wall and its base (depth range from 1740 m to 3100 m) and density of megafauna in the depression at the fracture zone bottom (4200–4500 m depth) were evaluated. At depths between 1700 and 2500 m hexactinellid sponges were most common and diverse. Deeper parts of the wall and its base were dominated by anthozoans (especially gorgonian corals) and echinoderms. A set of dominant species in the lower bathyal in the study area was different from that on the lower continental slope in the north-east Atlantic (Porcupine Seabight). An important contribution to local species richness of ‘rare’ species was demonstrated. The elpidiid holothurian, Kolga nana, occurred at high density in the abyssal depression.

The effects of winter flooding on the intertidal macrobenthic assemblages in the Guadiana estuary were studied by analysing several ecological parameters (abundance, biomass, species richness, diversity, degree of dominance of annelids and deposit-feeders species and number of predator species) as well as changes in the composition of the assemblages. Significant and systematic differences were found in the values of the ecological parameters, especially between winter and summer. We found a significant interaction between the factors ‘time’ and ‘site’, attributable to changes in abundance and composition of the assemblages. The assemblages showed a predominance of some opportunist species in most of the estuary after the flooding, suggesting that these species benefited from the new environmental conditions. Conversely, the assemblages in the mouth of the estuary were severely affected as was shown by the negative changes in biomass, species richness and diversity. These converse responses of the intertidal estuarine assemblages represent effects of flooding different from both catastrophic and negative effects on macrofaunal assemblages.

Using data available from the literature, patterns of biomass, production and productivity of sandy-beach macrofauna populations were examined, considering environmental (temperature, exposure, grain size and beach slope) and biological variables (life span and mean body mass) and feeding and taxonomic groups. A total of 102 estimates of both production and biomass and 105 estimates of P/B ratios were collected from 52 studies carried out between 42°46′S and 54°05′N, for 83 sandy-beach macrofauna populations. The negative relationship between P/B ratio and beach slope for the supralittoral amphipods agrees with the Habitat Safety Hypothesis, according to which these forms would show higher mortality in dissipative than in reflective beaches. The observed higher production of filter-feeders in exposed than in sheltered beaches suggests that more food is available for filter-feeders in exposed beaches. The higher production of filter-feeders (represented by bivalves and decapods), than of scavengers/predators (peracarids and gastropods) showed the importance of filter-feeders in the food web of sandy beaches. The P/B ratios were strongly related to life span, but weakly or not related to the mean body mass. The high amphipod P/B ratio was attributed to the short life span of these crustaceans; conversely, gastropods showed the lowest P/B ratio, in accordance with their longer life span. The observed differences in biomass, production and P/B ratios within crustaceans and molluscs were attributed to differences in life-history traits and feeding mode.

Seasonal changes in spatial structure of biomass of submerged aquatic vegetation (SAV) and environmental variables were evaluated in Celestun Lagoon, an estuarine habitat in Mexico. Geostatistical techniques were used to evaluate spatial autocorrelation and to predict the spatial distribution by kriging. The relative contribution of 11 environmental variables in explaining the spatial structure of biomass of SAV was evaluated by canonical correspondence analysis. Spatial partitioning between species of SAV was evident: the seagrasses Halodule wrightii and Ruppia maritima dominated the seaward and central zones of the lagoon, respectively, whereas the green alga Chara fibrosa was constrained to the inner zone. The spatial structure and seasonal variability of SAV biomass were best explained by organic carbon in the sediments, salinity and total suspended solids in the water column. Analysis at different spatial scales allowed identifying the importance of spatial structure in biotic and abiotic variables of this estuarine habitat.

Samples were collected from 10 stations distributed through three sectors in Guanabara Bay during two consecutive years, in order to determine factors that influence the spatial pattern of molluscs and to describe the structure and composition of this community in a eutrophic estuarine system on the Brazilian coast. Although only one species, the gastropod Heleobia australis, comprised 77% of mollusc abundance, 59 species were identified in the bay. In addition to H. australis, three other species were dominant: the gastropod Anachis isabellei and the bivalves Americuna besnardi and Ervilia concentrica. The mollusc communities were significantly influenced by the spatial gradient; the outermost sector has marine conditions, and the other sectors are typically estuarine, leading to differences in the composition and abundance of molluscs. The outermost sector showed the highest diversity, which gradually decreased towards the innermost sector where the dominance of a few opportunistic species is favoured by highly organic mud sediments. Sediment type was strongly correlated with mollusc occurrence in the bay. Guanabara Bay showed two indicator species: the bivalve E. concentrica of the outer sector, and the gastropod H. australis of the intermediate sector. Our results suggest that benthic molluscs in Guanabara Bay show characteristics related to levels of environmental impact. A monitoring programme based on this community is needed to evaluate the effects of human impacts on this community and to monitor changes in its biodiversity in Guanabara Bay.

Self-Organizing Maps (SOM) have been used for patterning and visualizing ten environmental parameters and phytoplankton biomass in a mactrotidal (>10 m) Gyeonggi Bay and artificial Shihwa Lake during 1986–2004. SOM segregated study areas into four groups and ten subgroups. Two strikingly alternative states are frequently observed: the first is a diverse non-eutrophic state designated by three groups (SOM 1–3), and the second is a eutrophic state (SOM 4: Shihwa Lake and Upper Gyeonggi Bay; summer season) characterized by enhanced nutrients (3 mg l−1 dissolved inorganic nitrogen, 0.1 mg l−1 PO4) that act as a signal and response to that signal as algal blooms (24 µg chlorophyll-a l−1). Bloom potential in response to nitrification is affiliated with high temperature (r = 0.26), low salinity (r = −0.40) and suspended solids (r = –0.27). Moreover, strong stratification in the Shihwa Lake has accelerated harmful algal blooms and hypoxia. The non-eutrophic states (SOM 1–3) are characterized by macro-tidal estuaries exhibiting a tolerance to pollution with nitrogen-containing nutrients and retarding any tendency toward stratification. SOM 1 (winter) is more distinct from SOM 4 due to higher suspended solids (>50 mg l−1) caused by resuspension that induces light limitation and low chlorophyll-a (<5 µg l−1). In addition, eutrophication-induced shifts in phytoplankton communities are noticed during all the seasons in Gyeonggi Bay. Overall, SOM showed high performance for visualization and abstraction of ecological data and could serve as an efficient ecological map that can specify blooming regions and provide a comprehensive view on the eutrophication process in a macrotidal estuary.

The feeding habits of the pelagic stingray (Pteroplatytrygon violacea) were studied using 84 stomachs of specimens caught in the northern Adriatic Sea in the period from April 2004 to October 2005. Percentage of empty stomachs found was overall very low, being a bit bigger in smaller specimens. The diet consisted of two main taxonomic groups such as teleost fish and cephalopods, but few specimens of crustaceans were recorded as well. The main food item was represented by anchovy, while cuttlefish and red band fish represented the alternative preys. Prey size was positively correlated with the size of predator. The proportion of anchovies in the diet grew with size of predator, while the one for red band fish decreased. The stingray was confirmed to be a top predator of pelagic fish species, although the presence of benthic prey shows that it feeds also at the bottom.

This paper describes the development of a method for quantitative measurement of the elemental composition of particulate matter (PM) in seawater. This method is based on use of wavelength dispersive X-ray fluorescence (WDXRF) analysing PM harvested on various filter types. As the amount of material is less than a monolayer of cells on the filters we reduced the need for absorption correction. Given the appropriate combination of filters and elements the detection limits are low: <1 µg/filter for carbon (C), nitrogen (N), and <0.1 µg/filter for silicon (Si), phosphorus (P), calcium (Ca) and iron (Fe). The analytical range used was 90–750 µg C, 23–116 µg N and 7–30 µg P, depending on the filters applied. Calibration constants for the elements included in this study were obtained from analysis of known quantities of chemical compounds on filters or silver plates. For carbon and nitrogen we also used comparative measurements of Synechococcus sp. cultures by CHN analyser and WDXRF. We harvested PM from 150 ml to 2000 ml on each filter in three replicates, obtaining less than 5% analytical variability between the replicates. One of the challenges using WDXRF as proposed here is the absorption of X-ray signals by the filter and variability of cell/particle sizes, and, consequentlyly, the variability of harvested PM on various filters. We find that an anodisc filter is best suited for C and N, while polycarbonate filters are best for heavier elements. Here we present analytical details and some data from field experiments related to C, N, P, Si, Ca and Fe in particles from seawater.

In this work, we evaluated the influence of long rocky jetties (~5 km) on fish abundance and diversity between sheltered and exposed marine sandy beaches. We also described and compared the fish community structure and investigated the relationships between environmental variables and fish assemblages. Fish were collected monthly with a beach seine net from May 2001 to May 2002 at the Cassino and Mar Grosso beaches. Twenty-nine taxa were caught and the fish assemblage showed similar composition between beaches (Sj = 62.1%; %Min = 52.3%), with 18 species in common. Most of the fish were juveniles, mainly young-of-the-year with sizes ≤60 mm total length. Eight species (Trachinotus marginatus, Mugil liza, Brevoortia pectinata, Menticirrhus littoralis, Menticirrhus americanus, Odontesthes argentinensis and Oncopterus darwinii) were the most abundant, accounting for 95.6% of the total catch. At both beaches, only T. marginatus, M. liza and M. littoralis were frequent and abundant, but with some differences in their relative abundance. The canonical correspondence analysis results showed that temperature had the highest correlation with fish abundance. Seasonal changes in fish assemblage structure were evident, with a greater species diversity and abundance in the spring and summer. The overall results indicate that the presence of jetties had no effect on fish assemblages of adjacent sandy beaches. Moreover, differences between beaches were related to some species abundance and not to differences in the number and composition of species between beaches.

The feeding habits of the apron ray, Discopyge tschudii, were investigated, off Uruguay and northern Argentina, and we tested the hypothesis that the diet changes with increasing body size, between sexes and seasons using a multiple-hypothesis modelling approach. Discopyge tschudii preys mainly on polychaetes (88.77% index of relative importance (IRI)) followed by siphons of the clam Amiantis purpurata (8.13% IRI) and amphipods (3.08% IRI). Ontogenetic, sexual and seasonal changes were found. Larger individuals of D. tschudii consumed buried polychaetes more often. The consumption of errant polychaetes was higher in males and in the cold season. Also, amphipods were preyed on more heavily by females and the number of siphons of A. purpurata consumed was higher in the cold season.

Macrofaunal community structure is determined by a number of environmental variables. The riverine run-off during the monsoon brings about drastic changes in the physico-chemical parameters of a tropical estuary. The aim of the present study was to investigate the influence of rainfall in structuring the benthic macrofaunal community of a tropical estuary. The temporal dynamics of the macrobenthic community in the monsoon dominated Mandovi estuary (central west coast of India) was studied fortnightly from June 2007 to June 2009. A fixed location, downstream of the Madovi river, was sampled for benthic and water parameters. Ten replicates were collected during each sampling date using a Van Veen grab (0.04 m2). The macrofaunal abundance showed temporal fluctuation. The multivariate analysis showed the clustering of the samples linked to the environmental parameters (CCA and LINKTREE). The temporal variation observed in the macrofaunal abundance was basically due to changes in abundance of the dominant species. The variation in macrofaunal abundance was brought about by the recruitment and settling of re-suspended adults. It can be concluded that the macrofaunal structuring is influenced by temporal changes in the environment associated with the annual monsoon rainfall. Hence climate induced changes in the monsoonal pattern may affect the macrobenthic assemblages of tropical estuaries.

The diets and trophic ecology of the dominant fish species from the marine coastal region of Aveiro (north-western Portugal) caught during a summer survey were studied. Mysids were the most important prey group for the fish assemblage analysed. As a consequence, there was a high dietary overlap between species and a low incidence of piscivory. Nevertheless, a clear segregation of trophic niches was observed, with one group (comprising the species Chelidonichthys cuculus, Callionymus lyra, Dicologlossa cuneata and Pomatoschistus lozanoi) showing a stronger preference for infaunal epibenthic prey, such as polychaetes and amphipods, another group (including Arnoglossus imperialis, Arnoglossus laterna, Chelidonichthys obscurus, Chelidonichthys lucernus, Echiichthys vipera, Pagellus acarne and Trisopterus luscus) preying mostly upon suprabenthic prey, mainly mysids, and a third group (Engraulis encrasicolus and Trachurus trachurus) feeding largely on planktonic prey like copepods. Some species, including A. imperialis, C. lyra, E. vipera, T. trachurus and T. luscus, showed ontogenic diet shifts that may be related to the habitat occupied by different size-classes and/or to their ability to capture prey of different size.

The rising impact of invasive species and climate change on Mediterranean fish biodiversity highlight the urgency to evaluate the current status of natural assemblages. Here we investigated the rocky-reef fish of Malta and Lampedusa (Strait of Sicily, Mediterranean Sea), two islands of high biogeographical importance subjected to a different level of protection and anthropic pressure. By using underwater visual census, a total of 192 counts were performed in May–June and September–October 2007 using a hierarchical spatial design and four depth layers. Overall, 23 families and 61 different taxa were recorded. Out of them, two highly invasive species were censused (i.e. Siganus luridus and Fistularia commersonii) with relatively low abundances. Native Labridae and Sparidae shape the assemblage structure of both islands, and thermophilic species such as Sparisoma cretense and Thalassoma pavo occur with high densities. The fish assemblages of Malta and Lampedusa were relatively similar in species composition, richness and total abundance. Nevertheless, multivariate analysis depicted significant differences between these two islands, mainly attributable to the unevenness of Labridae. Significant differences in the size distribution of the most abundant species were detected between islands, with parallel variation across time. The pattern of spatio-temporal variability of the whole assemblage structure strongly resembled that of nekto-benthic fish, hence pointing out the relevance of this guild as an indicator species group in future monitoring activity. This study will serve as a current baseline against which future changes in the central Mediterranean fish assemblages can be assessed.

Macrobenthic data from estuaries along the Pernambuco coast in north-eastern Brazil were analysed to evaluate the effect of sieve mesh size (1.0 mm × 0.5 mm) and sampling depth (0–10 cm × 0–20 cm) on the description of infaunal communities, in an attempt to discuss standardized sampling procedures for different ecological studies objectives in these ecosystems. In general, the difference in sieve retention was less evident for biomass but was important for abundance: the 1.0 mm sieve retained only 27% of total individuals but 77% of total biomass. Regarding sampling depth, the 0–10 cm layer contained most individuals (94%) but contributed just 64% of the overall biomass. Although no strong differences in community structure were observed at most sites with the use of different sieves, the correlations among community dissimilarity using different meshes with environmental parameters (organic matter, total-N and microphytobenthos) indicated that the use of the 0.5 mm sieve will allow a better evaluation of the status of these estuaries. The results also highlight the importance of taking the vertical distribution of tropical macrofauna into account for quantitative estimates: for taxa composition and abundance the top layer is clearly essential, whereas for biomass the deeper layers should also be considered.

Larval survival during planktonic dispersal is crucial to the connectivity among benthic populations. Although predation has been suggested as an important cause of larval mortality, this process has rarely been quantified in the field. We measured the abundance of various larval species in the water column in St George’s Bay, Nova Scotia, Canada, on 3 different occasions in summer (August 2008, July and August 2009), the period of high larval abundance in our region. We sampled four numerically dominant predators (scyphozoans: Cyanea capillata and Aurelia aurita; fishes: Gasterosteus aculeatus and Merluccius bilinearis) and lobster larvae near the water surface with a neuston net and other larval species in the water column (3 m depth) with a ring net. Larvae found in the gut contents of the predators included various species of gastropods, crustaceans and bivalves, and these were more abundant in the scyphozoans than the fishes. We attribute these differences to variation in predation method. For certain larval taxa, we found significant differences between the proportional abundance in the guts of C. capillata and in the water column, indicating prey selectivity. This study evaluates the potential impact of predation on larval survival and indicates that the presence of predators can cause changes in abundance and consequent taxonomic shifts in species dominance of larvae, influencing their successful subsequent recruitment to the benthos.

To analyse temporal distributions of microplankton populations and relationships to environmental conditions in marine ecosystems, a dataset of microplankton communities was investigated using a range of statistical methods. A total of 164 microplankton species comprising 100 microalgae and 64 ciliates were identified from 120 samples, respectively. Both planktonic microalga and ciliate assemblages showed temporal patterns and were significantly correlated between their temporal variations in abundance. The microplankton communities were characterized by 14 ciliates (e.g. Strombidium sulcatum, Tintinnopsis tubulosoides and Strombidium cheshiri) and 18 microalgae (e.g. Skeletonema costatum and Alexandrium tamarense). Multiple regression analyses showed that the interspecies correlations among these dominant species represented a complex network with a clear seasonal shift. Temporal pattern of microplankton communities was significantly correlated with the environmental variables such as temperature, salinity and nitrate nitrogen. The results suggest the clear species distribution and temporal dynamics of microplankton communities in response to environmental changes, and multivariate statistical approaches were a useful tool to reveal the species distribution patterns and complex microplanktonic interspecies correlations in marine ecosystems.

Biological traits analysis (BTA) is considered to be a powerful technique for describing the ecological functioning of marine benthic assemblages. This study is the first to apply BTA to assess differences in the traits of benthic faunal assemblages between areas exposed to heavy and light trawling in a major upwelling ecosystem along the west coast of southern Africa. The data were collected from two sampling locations in Namibia and six sampling locations in South Africa. The intensity of trawling varied from area to area. Significant differences in biological traits (BT) were detected between heavily and lightly trawled areas. Weighted infaunal traits showed significant differences between heavily and lightly trawled areas for 17% of the traits investigated, while 24% of epifaunal traits investigated were significantly different between areas of different trawling intensities. This suggests that the measured BTs of the epifauna might be more sensitive to trawling disturbances than BTs of the infauna. The infaunal traits differed significantly between areas with larger or smaller proportions of sand and mud. Nevertheless, more of the significant differences in infaunal BTs were related to variations in trawling intensity than to variations in sediment composition. Significant modifications of BTs are likely to lead to modified functioning of the community and provide more general potential indicators for management than those based on species. The study confirms the need for more basic biological and life history data on macro-benthic invertebrates but nevertheless shows that BTA detected specific features that correlate with trawling intensity and that these features may be important for epifaunal assemblage functioning.

Near-shore recent benthic foraminifera from three ecologically important (Olive Ridley turtle congregation sites) but vulnerable sites encompassing 23 sampling stations (12 in Rushikulya, 5 in Devi and 6 in Gahirmatha) along coastal Orissa, north-west Bay of Bengal (BoB) in India were studied for the first time for their composition, distribution and assemblage patterns. Thirty-nine species of benthic foraminifers (from 6 orders and 23 families) were identified of which all 39 were present in Rushikulya, 22 in Devi and 12 in Gahirmatha with abundance ranging from 35–2620 individuals/10 cm3 in the sediments. The communities across the sites were dominated by eurytopic rotalids followed by miliolids and textularids. Benthic foraminifer assemblages were found to be dominated by Ammonia species complex (up to 38% in Rushikulya, 64% in Devi and 22% in Gahirmatha). Agglutinated foraminifers were infrequent in the sediments (7 species in Rushikulya, 4 species in Devi and 3 in Gahirmatha) on the other hand, being dominated by Quinqueloculina agglutinans in Rushikulya and Trochammina macrescens and Ammobaculites agglutinans in Devi and Gahirmatha. The substrates along the study sites were found mostly to be sand dominated and in some of the stations sediment composition influenced the foraminifer distribution pattern. The present findings on the assemblage patterns of benthic foraminifers from three coastal settings in Orissa along the BoB are comparable with previous reports from other sandy coastal ecosystems in the world. Overall these data provide valuable insights into the distribution and assemblage patterns of benthic foraminifers from the BoB coastal regions.

Mesozooplankton was studied during 2008 in coastal waters of the İskenderun Bay in order to determine seasonal changes in abundance, biomass, community structure and their relationship with environmental factors. Samples were collected seasonally at five stations using WP-2 net of 200 µ mesh size by vertical hauls. A total of 23 planktonic groups including 30 copepod species, 4 cladocerans and 4 chaetognaths were identified. Copepods were the most important group during the whole period of survey. Penilia avirostris was found to be dominant in spring, while Paracalanus parvus in summer and winter, and Acrocalanus gibber in autumn. Mesozooplankton abundance varied from 438 ind m−3 (autumn) to 7163 ind m−3 (spring), while biomass varied between 2.2 mg m−3 (summer) and 52.9 mg m−3 (autumn). Differences in abundance and biomass between seasons were statistically significant (P < 0.01). Clear seasonal distribution patterns were observed in the area. Two peaks in abundance were defined: a major peak in spring and a second minor one in autumn. It seems that the trophic element was the main factor affecting the density distribution of zooplankton populations, whereas species distributions were more affected by hydrographical parameters, namely: seawater temperature and salinity.

The trophic structure of organisms is an important aspect of the ecosystem as it describes how energy is transferred between different trophic levels. Here, we studied the diet and foraging ecology of 144 individuals belonging to five abundant fish species of subtidal habitats at Isla Robinson Crusoe. Sampling was conducted during the austral spring and summer of 2007 and 2008, respectively. The shallow subtidal habitat is mainly characterized by the abundance of two types of habitat: foliose algae and encrusting invertebrates. Diet and trophic characteristic of fishes were obtained by volumetric contribution and frequency of occurrence of each prey item. Of the five species studied, one is herbivorous (juvenile Scorpis chilensis), four are omnivores (Nemadactylus gayi, Malapterus reticulatus, Pseudocaranx chilensis and Scorpis chilensis adult), and one carnivore (Hypoplectrodes semicinctum). The dietary diversity index was relatively low compared to other temperate reef systems, which could indicate a low availability of prey items for coastal fishes. The morphological parameters indicated that cranial structures and pairs of pectoral fins influence the foraging behaviour. Differences in fin aspect ratio among species provided insight about fish depth distribution and feeding behaviour. These results suggest important adaptive changes in the depth gradient of fishes in the subtidal environments of this island. According to our records, this is the first attempt to characterize the trophic ecology of the subtidal fish assemblages at Juan Fernandez Archipelago, revealing the need for testing hypotheses related to selective traits that may enhance species coexistence in oceanic islands.