The macrofauna of samples collected with a box-corer from northern Adriatic Sea muddy bottoms in five survey campaigns from 1985 to 1993 has been analysed separately in sediment strata of varying depth. Samples were collected before, during and after the dumping of large amounts of inert particulate material that covered the seabed and caused an almost total defaunation. After this disturbance the seabed was recolonized by a new community. This new community differed from the original one mainly on account of the abundance of Mysella bidentata, a small bivalve filter or surface deposit-feeder. In the original community M. bidentata was confined to the more superficial sediment layers (0–5 cm) at low population density. In the new community it was very abundant and evenly distributed even in the deep layers (5–20 cm). Analysis of species association performed on data from each of the 54 corer samples collected in the last sampling period, points to a marked association between M. bidentata and Nephtys incisa in deeper sediment layers. Deep layer colonization by Mysella in association with the burrowing polychaete N. incisa suggests a case of commensalism between these two species.

The diet breadth and diet overlap of two co-existing species of flatfish, plaice (Pleuronectes platessa) and dab (Limanda limanda) inhabiting a shallow bay in south-west Ireland are compared. They were shown to vary with the resource matrix, the gut region and the sample size. Diet breadth was calculated using Levin's index and diet overlap calculated using Horn's index. Values of diet breadth were considerably less for numerical abundance data when compared to percentage occurrence data. Similarly, diet overlap values were less for numerically derived data. In dab, diet breadths were significantly lower for stomach-only contents than for intestine-only or whole gut contents. In plaice, there were no significant differences in diet breadths between gut regions. Significantly lower diet overlaps for stomach-only data were also found. Reducing the size of sample to N=30 and N=10 resulted in increases in the calculated value of diet breadth, by as much as 0·13 and 0·34 respectively, these increases were frequently significant. The same reductions in sample size for diet overlap decreased overlap values by 0·02 and 0·13 respectively, significant only when sample reduced to N=10.

The breeding season of Nerophis lumbriciformis (Pisces: Syngnathidae), has not yet been determined for the southernmost part of its range. A total of 863 individuals was examined between March 1997 and November 1999. In Portugal, the breeding season of this species occurs throughout the year, with a marked reduction during summer and autumn, whilst in Britain it occurs from May to September. Despite these temporal differences, the water temperature at which breeding takes place is similar in the two areas (13–16°C). Together with preliminary laboratory observations with animals kept at different temperatures, these data support the hypothesis that the decrease in breeding activity during summer and autumn in Portugal is due to an inhibitory effect of high water temperature.

Littoraria ardouiniana and Littoraria melanostoma are common snails in Hong Kong, living and feeding on mangrove trees. Gut content and stable isotopic analyses were conducted to investigate the littorinid's diets. Gut content analyses revealed these snails ingested bark, epidermal plant cells, fungi, and microalgae, but that broken plant cells were the most abundant food items in the stomach and faecal contents. The gut contents of the two littorinid species, either from the mangrove trees Kandelia candel or Aegiceras corniculatum, were similar and showed little temporal variation throughout the year. Dual stable isotopic analysis, which investigated the δ13C and δ15N values of the littorinids and their potential food items, indicated that these littorinids might feed on mixed diets composed of parts of the mangrove trees and other items available on the trees such as phylloplane fungi, microalgae and cyanobacteria. These epiphytic mangrove littorinids are generalist grazers which graze on the substratum non-selectively as they are constrained on their host trees, and their diets are, therefore, dependent on food availability on the trees themselves.

The macrofauna of molluscs associated with soft bottoms in the Bay of Cádiz (southern Spain) was studied monthly from February 1994 to January 1996. The number of species (63) is high for a soft bottom and is related to environmental characteristics (growth of macrophytes) and the biogeographical setting of the studied area. Corbula gibba (∼90%) was the dominant species in this taxocoenosis together with the gastropod Nassarius pygmaeus and the bivalves Pandora inaequivalvis, Parvicardium exiguum and Macoma melo. The most frequent species during the two years was also the bivalve Corbula gibba (100%) followed by the gastropods Nassarius pygmaeus, Tricolia tenuis, Rissoa membranacea and the bivalve Macoma melo. Total abundance of the taxocoenosis in both years reached higher values in spring. The dynamics of the ecological indices such as diversity or evenness, and the species richness showed a similar pattern in both years, with low values of diversity and evenness together with high species richness in spring and summer months and the reverse in autumn and winter. The qualitative correspondence analysis of monthly samples shows an ordination related to seasonality in both studied years, however the values of Jaccard's coefficient do not indicate significant boundaries among the monthly samples. The quantitative correspondence analysis shows an ordination and grouping of samples related to the biology of species, particularly with the recruitment of C. gibba, the dominant species. The existence of similar trends in the structure of the taxocoenoses over both years, and the seasonality highlighted by the qualitative correspondence analysis, seems to indicate a certain stability of the ecosystem.

The stomach contents of 16 bottlenose dolphins Tursiops truncatus (Cetacea: Odontoceti) stranded in the Spanish Mediterranean coast were examined. Remains and size of prey were analysed and correlated with the ecological characteristics and behavioural patterns of this dolphin. Fish and cephalopods represented the main diet components, and hake Merluccius merluccius was the most important prey. The food habits were considered as mainly demersal according to the characteristics of the prey. The study suggested ontogenic and sexual differences in feeding behaviour based on diet composition and hake size. The potential causative factors, particularly as they relate to dolphin social structure, are discussed.

Ecological aspects of the marine tucuxi dolphin, Sotalia fluviatilis (Cetacea: Delphinidae), remain poorly known. Important information can be gathered in long-term studies using photo-identification. Using this methodology, the authors present the first evidence of site fidelity for marine tucuxis in the Cananéia Estuary (25°03′S 48°01′ W), south-eastern Brazil. A total of 86 easily recognizable individuals was catalogued from June 1996 to August 2001, but most of them have been sighted from May 2000. From June 1997 to August 2001, three female tucuxis were sighted on nine (KN #19), 22 (KN #30) and 28 (KN #10) different days in a relatively small area (∼16 km2). Each of them was observed with a calf in 1997–1998 and again with a new offspring in 2000–2001. Thirteen other individuals were reported on eight to 19 different days in the same area between May 2000 and August 2001. Our observations lead to conclusions on the evidence of site fidelity and indicate that calving intervals may range between two and three years for this species in the surveyed area.

We challenge a conclusion reached by Barnes & de Villiers in a paper that was recently published in this Journal, viz that certain benthic invertebrates occur in lower abundances in lagoons than in intertidal soft-bottom areas and that this difference is due to lower food supply at lagoon bottoms. Our experience in the Wadden Sea shows that food does not limit the abundance of primary consumers in areas where environmental conditions are harsh. Such conditions prevail in most of the upper half of the intertidal which is characterized by low abundance of zoobenthos despite a high food supply.

The coexistence of three taxa of Codium (Chlorophyta: Codiaceae) was examined on wave-swept shores of western Ireland: the introduced macroalgae Codium fragile ssp. atlanticum and ssp. tomentosoides and the native Codium tomentosum. In spring 1999 and 2000, four sites were monitored to evaluate whether past predictions regarding temporal changes and species replacement occurred. Introduced and native species of dichotomously branching Codium occurred at four tidal levels: in tidepools in (i) the upper barnacle zone; (ii) the mid barnacle/fucoid zone; (iii) the mussel zone, and (iv) on emergent substrata in the red algal turf/kelp zone. Codium fragile ssp. atlanticum and ssp. tomentosoides grew together in 11·9% of surveyed pools containing Codium. Compared to 1971 censuses, C. fragile ssp. atlanticum had increased in relative abundance at all tidal levels, and the dominance of C. fragile ssp. tomentosoides had declined. The native C. tomentosum constituted the same percentage of the population as it did in 1971. Pool availability and primary rock surfaces were not limiting at most sites, indicating that inter-subspecific and inter-specific competition could not account for temporal changes in Codium distribution on Irish shores. Ecological constraints other than intra-generic competition may have contributed to the purported long-term changes in Codium abundance.

Mercury determinations were carried out in mussels (Bathymodiolus azoricus) from three Mid-Atlantic Ridge hydrothermal vents (Lucky Strike, Menez Gwen and Rainbow) and shrimps (Rimicaris exoculata and Mirocaris fortunata) from Rainbow. Among the three hydrothermal vents, mussels of Menez Gwen show the highest levels of total Hg and comparing mussels and shrimps from Rainbow the former show more Hg than shrimps. Mussels from different hydrothermal vents are exposed to different kinds of environment which may result in distinct bioaccumulation processes. Detoxification processes in shrimps are related to the low concentrations found. When compared with coastal species from unpolluted sites, mussels show higher concentrations of total Hg and shrimps lower levels. The methyl-mercury concentrations found were very low, not exceeding the detection limit of the technique.

The relationship between sperm reservoir and total spermatophore length among 168 spermatophores from 44 species in 11 genera has been considered. Bivariate plots show that four Atlantic species of the genus Eledone produce spermatophores with relatively large sperm reservoirs that differ from all others. Measurements of the remaining spermatophores are so tightly correlated that a single equation explains over 96% of the variation. Functional constraints on gross spermatophore morphology may be so strong that males cannot manipulate sperm reservoir size independently of spermatophore size to maximize the sperm delivered at a single copulation. Alternate means to assure male paternity may have evolved in the group as a result. Despite the overall uniformity of the relationship among all species other than those of Eledone in the Atlantic, these measurements distinguish the overtly similar species Octopus bimaculatus–Octopus bimaculoides and separate Benthoctopus januarii from all others.

The population of Paguristes erythrops (Crustacea: Anomura) was studied based on seasonal abundance, size–frequency distribution, sex ratio and reproductive period (percentage of ovigerous females). Specimens were collected monthly by SCUBA diving in the infralittoral area of Anchieta Island, Ubatuba. A total of 543 individuals was analysed. Animal size (minimum and maximum shield length, respectively) was 1·7 and 11·8 mm for males, 1·7 and 10·3 mm for non-ovigerous females, and 3·2 and 7·8 mm for ovigerous females. The sex ratio was 0·91:1. Sexual dimorphism was recorded by the presence of males in the largest size-classes. The absence of ovigerous females during winter months (June to August) and their high incidence from January to March indicated discontinuity in the reproductive cycle, suggesting that females become ovigerous and breed in the summer, with the spawning period lasting from spring to autumn. This strategy of reproduction probably was based on competition with other coexisting species in this area.

The taxonomic identity of the common subtidal ctenostomate bryozoan Alcyonidium diaphanum is resolved using comparative morphological and molecular genetic techniques. The newly recognized lectotype series and topotype specimens are described and illustrated. The incorporation of spicules and foreign particles during colony growth is described. Colony morphology and genetic characters of the three commonly occurring morphotypes are examined, showing that just a single genetic species may be recognized, based on the 12s rRNA and CO1 mtDNA genes. Mitochondrial haplotypes show no general correlation with either colony morphotype or geographical location.

A comparative study of some tagging methods for the great scallop (Pecten maximus) is reported and intended to increase reliability and reduce costs associated with tagging. Tags were tested for ease of application, legibility, visibility and retention prior to a 17-month study of Pecten maximus in suspended (pearl net) culture. Of the six adhesives tested (standard epoxy resin, rapid epoxy resin, underwater epoxy resin, dental cement, cyanoacrylate fluid and cyanoacrylate gel), rapid epoxy resin and both cyanoacrylates were successful, bonding strongly and quickly to scallop shells. Of the three tag types used, Shellfish Tags (Hallprint) were favoured because they were simpler to apply, more visible, easier to read, and held more data than both Micromarkers (Brady) and engraved codes. In long-term trials 550 scallops were double tagged with Shellfish Tags using cyanoacrylate gel. Loss rates were 16% for tags on the umbo and 0·4% for tags positioned in grooves near to the shell margin. Loss rates did not increase over the 17-month period.

When the mean adult length and mean clutch volume of marine turtles are examined, a clear pattern for larger species to lay larger clutches is evident, in accord with predictions that female size constrains the available space for carrying eggs. However, when compared with this general trend, the volume of clutches laid by flatback turtles (Natator depressa) are smaller than expected. The implication is that the unusually flat morphology of flatback turtles, provides an additional constraint on their egg carrying capacity.

Mats of articulated coralline algal turf are common on many rocky intertidal shores. The dense fronds provide a habitat for extremely diverse and abundant macrofaunal assemblages. Despite a large contribution to faunal biodiversity of rocky shores, little has been published about these assemblages. This study describes patterns of distribution and abundance of macrofauna in coralline turf on rocky shores around Sydney. In addition, the potential of environmental variables (sediment, epiphytes, length and density of coralline fronds) for determining these patterns was also investigated. Relatively consistent differences were found between macrofauna in low- and mid-shore areas at all times of sampling and on all shores. Although there was some variation among shores, there was generally significant variation in macrofauna between sites separated by tens of metres. Generally, a relatively small number of taxa were responsible for the great majority of dissimilarity between assemblages. Apart for the small bivalve Lasaea australis, however, these taxa varied between heights on the shore, among times of sampling and among shores. These data illustrate the important contribution that coralline turf has for biodiversity of faunal assemblages on rocky shores around Sydney. They also provide a basis for investigating biological processes and physical factors responsible for structuring patterns of biodiversity of macrofaunal assemblage in coralline turf.

Three species of microgastropods, Eatoniella atropurpurea, Eatonina rubrilabiata and Amphithalamus incidata, are common in various habitats at mid to low levels on intertidal shores in New South Wales, Australia. These habitats include patches of sediment, pebbles and algal turf. These species are very patchy, varying in abundance within and among habitats at scales of centimetres to many metres. This study describes laboratory experiments which tested hypotheses about differences in mortality and growth rates for each species in three different habitats: sediment, pebbles and coralline turf. There was greater mortality in coralline turf without sediment for E. rubrilabiata and A. incidata, whereas Eatoniella atropurpurea showed a greater mortality in sediment. Moreover, Eatonina rubrilabiata had a faster rate of growth in sediment, whereas Eatoniella atropurpurea grew more rapidly in coralline turf. The different rates of mortality and growth for these species in different habitats provide mechanisms which may partially explain the patterns of abundance in the field.

Evidence of sexual dimorphism in the mud-shrimp Upogebia stellata was observed in the abdomen length, total length, and also in the chelae. For the same carapace length, males had a shorter abdomen and, therefore, total length, whilst their chelae were larger and more robust than the females. Of the 91 U. stellata individuals examined, a single specimen was found to be of an intersex type, i.e. it exhibited both male and female external characteristics. Sexual dimorphism and intersexuality are discussed.