The effect of aerial drying of biofilmed surfaces to simulate a tidal emersion upon the settlement preferences of spirorbid and bryozoan larvae was investigated using choice experiments with still water conditions carried out in the laboratory. Aerial drying of biofilmed slates and pieces of Fucus serratus for 1 h at 20°C negated their usual settlement-inducing properties to larvae of Spirorbis spirorbis, S. tridentatus and Flustrellidra hispida. Such larval settlement preference may contribute to observed variations in the natural distribution of these species in the intertidal.

Stable carbon isotope measurements (δ13C) were used to assess the sources of carbon assimilated by the fan mussel Pinna nobilis, in sea grass Posidonia oceanica meadows, and an associated shrimp Pontonia pinnophylax which occurs within this bivalve's mantle cavity. The primary carbon sources available to both animals displayed a wide range of δ13C values, from −12·3 to −22·3‰. The δ13C and δ15N of Pinna nobilis and Pontonia pinnophylax suggest that they assimilate carbon from similar sources, occupy comparable trophic levels and that their association is commensal.

The distribution and spatio–temporal variation of Helicolenus dactylopterus (Pisces: Scorpaenidae) population was studied from 816 bottom trawls developed along the Iberian coast. Multifactor analysis of variance was used to test the differences in abundance and biomass and cluster analysis was applied to detect differences in population structure. The results showed a bathymetric and latitudinal gradient in abundance and population structure along three geographic sectors in the surveyed area. In the southern area, the species was more frequent and showed a wider bathymetric distribution range than northwards. The depth range with the maximum frequency of occurrence was also wider in the southern area than northwards. Similar trends were observed in terms of abundance and biomass, with the highest and lowest indices in the southern and northern areas, respectively. The age composition of the catches showed that the population consisted mainly of young-of-the-year and juvenile fish. This fraction of the population is well represented, at a mesoscale, along the whole surveyed area, but adults are well represented only at a local scale, at the deepest strata surveyed in the southern area. In this case, recruits of age 0 and juveniles up to 4-y old were restricted to depths shallower than 500 m, while adult fish older than 6 y of age appeared below this depth. In the southern area, seasonal changes in the population structure were also observed, with modes of small fish (3–6 cm) from March to June, as a consequence of the species recruitment to the bottom. Some direct and indirect factors of biogeographic, environmental and anthropogenic origin affecting the observed gradient are discussed.

Geostatistical analysis was used to investigate the effect of drift kelp on the spatial distribution of the sea urchin Tetrapygus niger. The positions of all sea urchins were mapped in four experimental plots in the rocky intertidal zone of the central Chilean coast. When drift macroalgae were added, the sea urchins left the substratum irregularities, increased in number inside the experimental plots, and tended to form a dense aggregation around the kelp. After the drift macroalgae was removed, the aggregations disappeared and the sea urchins returned to the depressions and/or interstices of the substratum. The results suggest that the influx of drift kelp is the triggering factor in the formation of dense aggregations of this species.

The anatomy of the hook apparatus that attaches egg strings to the fish parasites Haemobaphes cyclopterina, Lernaeocera branchialis, Lernaeocera lusci, Lernaeenicus sprattae, Sarcotretes scopeli and Pennella balaenoptera (Copepoda: Pennellida) is described and illustrated. The hook rises from a cupulate base, extending posteriorly and anteriorly in the body cavity. The suspension of the apparatus in the trunk of the different species differs, but the function is similar. The hook tip enters the genital antrum, nearly penetrates the proximal end of the egg string, and continues into a notch on the antrum wall. The apex of the egg string acquires a concave depression like the finger end of a glove. In this way the string is mechanically attached inside the female genital segment. The mobile ectoparasites Lepeophtheirus salmonis and Hatschekia hippoglossi have hooks which function similarly, but perforate the strings.

Enhydrosoma curvirostre is redescribed from archived and new material with particular attention to the structure of the mouthparts and other details of the fine structure not previously reported. It is shown that the species cannot be maintained in Enhydrosoma but is more closely related to Cletodes, the genus in which the original author placed it. However, it is shown that the species must be assigned to a new genus, Spinapecruris, as a result of possessing autapomorphies on the maxillule (only seven setae on the basis), thoracopods 2–4 (a large spine on the distal margin) and possibly the caudal ramus (proximal insertion of seta VII) and lacking apomorphies which may define Cletodes.

Microphytobenthos are significant primary producers in many coastal systems. It is therefore important to quantify their biomass and productivity. Chlorophyll-a is often used as an index for microphytobenthic biomass. However, complications arise as most studies of sediment properties have been on a millimetre scale, whilst chemical and biological gradients in the surface layers of sediment occur over a microscale. The development of a new technique, the Cryolander (Wiltshire et al., 1997; Wiltshire, 2000), now allows microscale analysis of the sediment surface. Areas of high and low diatom biomass were compared using two coring techniques of different vertical resolution; the Cryolander method, with a vertical resolution of 0·2 mm and plastic core tubes (coarse coring), with a vertical resolution of 5 mm. Results indicated that, except at extreme biomass levels, coarse coring does not detect statistically significant differences in chlorophyll-a between obviously diverse sample sites. This may lead to misinterpretation of seasonal and spatial data when coarse coring is used. Furthermore microscale sectioning allows distinctions to be made between chlorophyll-a measured in the photic zone (photosynthetically active biomass (PAB)) and chlorophyll-a measured below the photic zone (photosynthetically inactive biomass (PIB)), allowing accurate determination of biomass specific primary production.

This is the first report on the presence of basking sharks Cetorhinus maximus in Galician waters (north-west Iberian Peninsula) from sightings, strandings and incidental catches by fishing gear. Morphometric, biological, geographic and temporal data on 19 basking sharks recorded from 1988 to 1998 are presented. Average total length is 401·4 cm. Male:female ratio is 0·6. Seventy per cent of records are from incidental fishing catches in bottom gill nets. Approximately 74% of sharks were recorded during February, March and April, which may suggest that the species occurs seasonally in this area.

There is sometimes a significant bias in the sex ratio of fish caught by longline. Usually, more females than males are caught. The possible reasons for unequal sex ratios in longline catches are listed and discussed. One sex could be more common in the area where the fishery takes place because there really is an unequal sex ratio in the population or because the other sex preferentially occurs in different places. Alternatively, longline fishery might preferentially catch one of the sexes. This could be a result of size difference between the sexes and thus a different response to the given hook size or bait size. Finally, sexes could differ in their feeding behaviour. There is growing evidence that females—not only of fish—are ‘energy maximizers’: they find food faster and spend more time feeding than do males. Thus, fishing methods using bait are likely to catch a higher proportion of females than fishing methods that do not use bait.

The purpose of the present study was to assess the relationship between sediment composition and biological community structure in mixed sands and gravel deposits of the eastern English Channel. Although some species are clearly associated with particular sediment types, the results confirm the lack of correspondence between community composition of the benthos and particle size distribution in unconsolidated sand and gravel deposits. The results also suggest that sample-to-sample variability commonly recorded in the species composition of macrofauna may reflect significant under-sampling by conventional grab sampling techniques. The implications of this for environmental monitoring and impact studies is discussed.

Arcachon Bay was the last important shell culture area of the French Atlantic coast without a stock assessment of the accidentally introduced Crepidula fornicata (Gastropoda). Following a stratified sampling strategy, 205 stations were sampled with a dredge. The total biomass of C. fornicata was estimated at 155 tn (confidence limits: 72 tn) scattered on 2·4 km2, i.e. about 5% of the infralittoral area. This biomass is very low compared to other exploited shellfish sites. Amongst mean environmental parameters (such as bathymetry, temperature, salinity, sediment grain-size, anthropic activity), the major keyfactors differentiating Arcachon Bay from other French sites were searched to explain the differences in C. fornicata colonization pattern. It seems that the low biomass of C. fornicata, 30 y after its occurrence was first recorded in the bay, could be correlated to: (1) the scarcity of subtidal muddy sediments which are suitable for C. fornicata settlement; (2) the presence of large Zostera spp. beds on both intertidal and subtidal areas; and (3) the absence of bottom trawl fishing.  Growth, production and productivity (P/B) ratios were compared between five stations characterized by different hydrological and sediment parameters. Growth and productivity (0·3 y−1) were not affected by mean biomass suggesting a lack of population regulation by intraspecific competition.