Fourier spectral analysis was used to highlight a rhythmic dimension of the click repetition pattern of the sperm whale (Physeter macrocephalus). Analysis of numerous series of regular clicks only showed occasionally the previously described codas used for communication. Out of a sample recording of vocalizing sperm whales, an apparent cacophony, belonging to a year-round resident group foraging a few miles off the coast of Gran Canaria, the individual click sequences of four animals have been unravelled by cross-correlating their time wave shapes.

The Fourier spectrum, which yields the harmonic aspects of each isolated click sequence, shows a deterministic structure that appears as a strong modulating frequency. This shows that click production is not a random process and possibly characterizes, in fact, a signature of the animal. Here we introduce a new concept: this rhythmic modulation represents the acoustic signature of each individual sperm whale, which we have called RIME (rhythmic identity measurement). The RIME would allow a whale to distinguish its own echo time pattern from the background of other click trains during echolocation. The RIME appears to represent a new concept in communication strategies and might also be present in other-social-odontocete repertoires.

Density and size of Chromis fumea (Pisces: Pomacentridae) were regularly monitored during 13 months (from August 1996 to August 1997), on two artificial reefs in New Caledonia (south-west Pacific ocean): a ship-wreck (CT2) just after scuttling, and an assemblage of iron boxes (Caissons) sunk more than 50 years ago. The settlement of C. fumea was first observed 20 August 1996 and lasted 20 days. At the beginning the recruits were 1 cm size-class fish and at the end 2 cm size-class. This major settlement phase was again observed one year later (September 1997). A second minor settlement phase occurred in December 1996 on CT2. Significant immigration of adults was also observed between November 1996 (6 cm) and April 1997 (7 cm), indicating that this species is capable of medium range migration (>50 m). Population size decreased by 87·8% between the settlement of juveniles and the first immigration phase of adults. The final density of the 1996 cohort was 10·5% of the initial input of recruits on CT2 and 19·3% on Caissons. Initial density of recruits was 3·4 times higher on CT2 than on Caissons, whereas density of juveniles was similar at the end of the survey, indicating that post-settlement mortality was greater on CT2. Chromis fumea von Bertalanffy growth models were similar on CT2 and Caissons. This short-lived species is characterized by an initial rapid growth phase (K>3·36 y−1), with the fish reaching 68·5% of L∞ in three months, and a second slower growth phase (1 cm in ten months).

A new hand-held corer for meiofaunal sampling and vertical profile investigation was developed. Its design and use prevents problems connected with core compression caused by the use of a plunger for core extrusion as generally applied in common coring techniques. This represents an advantage when meiofauna vertical profiles are investigated. A comparison between vertical profiles obtained from the newly developed corer and from commonly used corers shows that non-extrusive techniques significantly reduce sediment core compression.

To examine the effects of submergence time, free-space availability, and larval supply on height-related differences in settlement density of Semibalanus cariosus, we monitored the daily settlement density in plots where all benthos were removed daily and in natural-community plots, which were left undisturbed, at two sites with different tidal heights: the centre and the upper limit of S. cariosus zone, during one settlement season. Settlement density was higher at the low-tidal site, where settler mortality was low, than at the mid-tidal site, where settler mortality was high. The between-site differences in settlement was determined by larval preference for height and not immersion time. The settlement preference for height was masked on days with high larval supply, since suitable settlement sites in lower height were saturated by settlers.

Cold vapour atomic absorption spectrophotometry (CV-AAS) was used to evaluate total mercury concentrations in Posidonia oceanica, after initial mineralization of the samples in a microwave oven. Measurements were taken of three leaf tissue types: the adult leaf blade, the adult leaf sheath, and the intermediate leaf blade. Plants were sampled monthly over a one year period at two sites presenting different degrees of pollution: Rosignano (Tuscany, Italy) and Tonnara (Corsica, France).

The mercury concentrations recorded in the different P. oceanica tissues were systematically higher at the more contaminated of the two sites, thus confirming the value of this plant as a biological indicator. The mercury concentrations observed exhibit seasonal variations, with higher concentrations recorded in winter than in summer. These variations seemed to be negatively correlated to the plant's phenology. Also, the mean mercury concentrations were generally lower in young tissue (intermediate leaf blade) than in the older tissue (adult leaf blade).

Plant size and aspects of the reproductive potential of monotypic and polytypic populations of Fucus spiralis and Fucus spiralis forma nanus were compared. The two formae were distinct, but the differences between them were less pronounced where they co-occurred, suggesting the possibility of a level of inter-forma gene flow. Fucus spiralis f. nanus plants pay a potential reproductive cost in that they produce smaller eggs than F. spiralis, but the two formae appear to have similar levels of total reproductive output (eggs per unit of receptacle tissue).

Numbers of naked amoebae (Gymnamoebae) inhabiting the lower intertidal zone of two sandy beaches were estimated using a novel enrichment cultivation method. Samples were collected between June and September, 1999. Beach sand at Kames Bay, Isle of Cumbrae, Scotland contained on average 2604 amoebae cm−3 while at Dania Beach, Florida, USA, sand harboured 4236 amoebae cm−3. This is the first study to focus on the abundance of naked amoebae inhabiting a sandy beach. These numbers are higher than densities generally reported for shallow subtidal sands and show that amoebae must be considered in future studies on the dynamics of sandy beach communities.

Each spring, a localized stock of herring (Clupea harengus, Teleostei, Clupeidae) spawn in the Blackwater Estuary (Essex, UK). The eggs are laid on a gravel bank (Eagle Bank) at the mouth of the estuary. Incubation takes three to four weeks and, after hatching, the larvae can be caught in the area for several months. In this paper, results are presented from a finite-element circulation model used to simulate tidal and wind driven flow fields for the region. A particle tracking model was then used to simulate the dispersal of young herring larvae, up to first feeding, hatching from the Eagle Bank. The simulations predicted that, over a period of 12 d, around 63% of particles would be retained in the area of the Eagle Bank at high water whilst 22% of particles would be further south towards the Buxey Sands. Over the same time, ∼7% of the particles released would be found in the River Blackwater itself. Imposing a steady state wind of 10 m s−1 from the south-west (the dominant wind direction during spring in this area) or north-east had the effect of moving the majority of particles into the river or offshore to the south respectively.

The fragmentation process in Hydractinia pruvoti (Motz-Kossovska, 1905) which live on shells inhabited by hermit crabs is activated by the intensity of water movement that induces a rapid and abundant production of propagules by transversal fission. Being produced by all kinds of polyps in the polymorphic colony, fragments are very different from each other both in shape and size. After their liberation, fragments first settle on the bottom, then dedifferentiate and produce a network of hydrorhizae from which new polyps arise.

Trigonioids represent the most plausible marine outgroup for freshwater palaeoheterodonts, yet details of their early ontogeny are scant. We utilized museum specimens and scanning electron microscopy to characterize the prodissoconch structure of the ‘living fossil’ Neotrigonia margaritacea. This species produces a large inflated prejuvenile shell (mean length ±SD=664±16.9 μm, N=8) that lacks both an umbone and a prodissoconch II. It is concluded that N. margaritacea does not rely on planktotrophy to fuel its prejuvenile ontogeny.

A molecular genetic analysis of Coris julis from different sites in the Mediterranean and the Atlantic and C. atlantica from the Cabo Verde Islands was applied to infer phylogenetic relationships between the taxa. More precisely, partial 12S mitochondrial rDNA sequence data were used in maximum parsimony, neighbour-joining, and maximum likelihood analysis to generate phylogenetic trees. The polymorphism observed indicated an important differentiation between the C. atlantica and C. julis specimens and supported the existence of two different species.

The variability in density estimates of intertidal, infaunal benthos due to the shape and tidal orientation of sampling devices is discussed. Although all intertidal sampling devices are fundamentally of the same design, three different cross-sections were investigated, square, circular and rectangular, with the first two of common use in intertidal sampling. Results demonstrated that tidal orientation of the sampling device does not induce variability in density estimates. Furthermore, no difference in density estimate could be detected between the square and circular cores, both having a very similar cross-section. In contrast, some species exhibited significant differences when comparing rectangular vs square/circular cores combined. It is postulated that these are caused by species-specific small-scale spatial patterns.

Hediste diversicolor from several populations on the Basque coast shows great intraspecific variation in the number of paragnaths (chitinous teeth) in its proboscis. Interpopulation variation in the number of paragnaths was observed in groups I and III. Most group numbers are strongly correlated; only group VI seems to behave independently. In general, the number of paragnaths is higher than those from earlier studies on other populations at locations along the whole latitudinal gradient of the species distribution; groups II and VI are the most stable. A significant relationship was observed between the paragnath number and the granulometry of sediment: in general the number is higher in coarse sandy sediments and decreases with the fine grain fraction.

The occurrence of developmental abnormalities in two ovoviviparous littorinids (Littorina neglecta and a barnacle-dwelling form of L. saxatilis) inhabiting the barnacle zone at Peak Steel, Ravenscar on the north-east coast of England was investigated. In general developmental abnormalities appeared to be a rare occurrence in both taxa. However, L. neglecta was found to have a significantly greater proportion of deformed embryos in their brood pouches than L. saxatilis B (Figure 1). A distinct seasonal variation in the number of developmental abnormalities was observed in L. neglecta, and it is suggested this is a result of broods developing outside of the main reproductive season being more prone to deformity.

The life history of the hydrozoan, Hybocodon prolifer, was observed. The polyp from the actinula larva forms the stolon soon after metamorphosis. The stolon is dormant during the warm seawater season. The polyp does not produce the medusa. In early winter the stolon starts to form the polyp, and the polyp produces the medusae. Subsequently the polyp forms the stolon. Experimentally the stolon can be induced to form the polyp at any time during aestivation by treatment with low temperature seawater. Neither the polyp from the actinula nor that from the aestivating stolon forms the next polyp. In this case the hydrozoan is solitary. When the polyp forms the stolon with branches, a polyp is formed from each branch after aestivation. In this case the hydrozoan is colonial. If the stolon piece is divided into several pieces, a polyp is formed from each piece. When the contents of the stolon are extruded, the extruded cells form a cellular mass in several hours, and undergo morphogenesis to form a polyp, as does an intact stolon. The stolon is covered by a thick perisarc, and the endodermal cells contain large quantities of yolk-like granules. A few nematoblasts are found dispersed among the endodermal cells.

A preliminary comparative analysis of colony growth and zooid size in the perennial bryozoan Flustra foliacea (Bryozoa: Cheilostomatida) reveals reduced colony growth in the Bay of Fundy relative to growth in the Menai Straits and the Skagerrak, while seasonal fluctuations in zooid size are in synchrony with temperature regimes. Such retrospective morphometric analyses may allow inferences of primary productivity and thermal regimes and provide insights into the life histories of both Recent and fossil bryozoans.

The first finding of the brittle star Amphiura securigera (Echinodermata: Ophiuroidea) in the Tyrrhenian Sea is reported. According to literature data, biotopic and edaphic features of the bottom indicate that this species preferentially lives in detritic mud-free biotopes characterized by good water circulation. Present data show that in the Mediterranean Sea A. securigera extends its bathymetric range as far as the circalittoral and upper bathyal floors.

The hyoid arch and branchiostegal rays of Paraliparis leptochirus (Pisces: Liparidae) and of Paraliparis murieli are described for the first time. The restoration of the validity of Eutelichthys Tortonese on the basis of the presence of only five branchiostegal rays in P. leptochirus, its type species, is proposed. Paraliparis murieli has, as the other Paraliparis spp., a hyoid arch with six branchiostegal rays. The endochondral pectoral girdle of P. leptochirus, P. murieli and P. hystrix is described for the first time, and some data about the girdle of P. edwardsi are given. Differences between P. hystrix and P. murieli, described simultaneously, and between P. murieli and P. australis are established.

Paragnath variation was examined in two populations of the epitokous form of the polychaete Perinereis cultrifera from the English Channel and the Algerian Mediterranean coast. Populations differ from each other in the mean number of paragnaths in groups I, II, III, V and VII–VIII, in the number of teeth per half jaw and in the morphology of paragnaths in the posterior belt. Individuals of the two populations studied share no common alleles at five loci involved in electrophoretic comparison. The general protein band patterns reveal 13 markers that discriminate between the Perinereis individuals. Congruence of all the reported results agree with the assignment that P. cultrifera is a complex of species, probably more than two.

The occurrence of the aristeid shrimp Hymenopenaeus debilis in the Mediterranean Sea is reported from two individuals collected in the Alborán Sea and off Eivissa (western Mediterranean) from depths of 668-679 and 1109-1140 m, respectively. Comments on the origin of the populations and biogeography of the species are related to the Mediterranean pseudopopulations hypothesis.