The present study describes the reproductive biology, population structure and life history traits of the abundant intertidal crab Xantho poressa. Between March 2007 and April 2008, a total of 1918 individuals were collected in Corrales de Rota (south-western Spain), a human-modified intertidal habitat characterized by an artificial high complexity. Suitable refuges for crabs (cobbles and boulders) are very abundant in this area and density (maximum of 50 ind*m−2) was directly related with the area covered by these stones. In spring and summer, size–frequency distributions showed a polymodal pattern with seasonal variations related to the incorporation of juveniles to the adult population. Newly settled juveniles were not found in the Corrales suggesting an ontogenetic migration from a distant recruitment habitat. The annual reproductive cycle was seasonal and successive peaks in the abundance of ovigerous females were observed in late spring and summer. Females probably produced multiple broods during a long intermoult period. The gonadosomatic index had a cyclic pattern of variation with peaks two weeks prior to those of ovigerous females; it was lower during the non-reproductive season. The hepatosomatic index was high during spring, decreased during summer and increased gradually at the end of the reproductive season. There was a monthly cycle of larval release resulting from a combination of a cyclic and synchronic ovarian maturity, oviposition and incubation; hatching took place during neap tides when the moon was at last quarter. The adaptive significance of the rhythmic reproduction and hatching observed may not be explained by the predator avoidance hypotheses. The overall sex-ratio did not differ from 1:1 but one male and several females coexist under a stone, indicating a female biased operative sex-ratio. The combination of a complex habitat, its use, and a strong sexual dimorphism suggest a refuge–defence polygenic mating system. The survival and fitness of X. poressa in the Corrales de Rota are probably enhanced by the availability of shelter, a consequence of a highly complex habitat, and probably, of human activity.

Laboratory observations on the formation of concentric growth ridges on the shell of small Pecten maximus revealed that their rate of production was related to the size of the shell and to the growth increment in a given period. These factors are related, naturally, and the larger the shell, the greater is the growth increment and the number of ridges produced in a given time. Also, in shells of a similar size the higher the growth rate, the larger is the width of each ridge and the greater is the number of ridges produced. Faster growth is achieved therefore by increasing the width and number of ridges. The rate of ridge production at 10 °C was less than half that at 14·5 °C in conditions which were otherwise identical.

In previous papers (Millar, 1952; 1954a; 1954*0 I have dealt with the re-productive cycle of several ascidians in Scottish waters, and in the present account observations are extended to other species.

The course of breeding was studied in the following species. Family Polyclinidae:Sidnyum turbinatum Savigny, Aplidium nordmanni (Milne Edwards), A.punctum (Giard), A.pallidum (Verrill) and Polyclinum aurantium Milne Edwards. Family Didemnidae:Didemnum candidum Savigny and Lissoclinum argyllense Millar. Family Clavelinidae: Clavelina lepadiformis (Müller).

Samples of Balanus improvisus were collected from 15 sites in the Baltic, the west coast of Sweden, the British Isles and North America. They were analysed with horizontal starch gel electrophoresis for 11 loci and with opercular plate morphometry for 10 metrical characters. Analyses of isozyme patterns revealed a high degree of genetic similarity amongst populations. The Baltic sites, however, showed less heterozygote deficiency than the British and American sites indicating higher stability and outcrossing in the Baltic. Morphometric characters showed somewhat more heterogeneity than isozymes. The Baltic was relatively more homogeneous by morphometrical characters than by isozymes compared with the other areas. Both analyses separated to some extent the three geographical regions from each other and clustered sites by salinity. Individuals at low salinity had relatively small opercular openings compared to individuals from high salinity.

This study reports the age estimation of marine tucuxi dolphins (Sotalia fluviatilis) found dead along the south-east coast of Brazil (24°40′S–25°30′S). The investigated specimens were collected from August 1995 to December 1998. Ages were estimated through the number of Growth Layer Groups (GLGs) from decalcified and stained thin sections of teeth. A total of 36 individuals was investigated. Estimated ages of marine tucuxis varied from zero to 29 years. The growth curve was attained from a modification of the von Bertalanffy equation applied to body length and age data. It was possible to estimate the total length of 97·8 cm in newborns, physical maturity was attained at seven years of age, and an asymptotic length of 179·8 cm.

The physiology of mesophotic Scleractinia varies with depth in response to environmental change. Previous research has documented trends in heterotrophy and photosynthesis with depth, but has not addressed between-site variation for a single species. Environmental differences between sites at a local scale and heterogeneous microhabitats, because of irradiance and food availability, are likely important factors when explaining the occurrence and physiology of Scleractinia. Here, 108 colonies of Agaricia lamarcki were sampled from two locations off the coast of Utila, Honduras, distributed evenly down the observed 50 m depth range of the species. We found that depth alone was not sufficient to fully explain physiological variation. Pulse Amplitude-Modulation fluorometry and stable isotope analyses revealed that trends in photochemical and heterotrophic activity with depth varied markedly between sites. Our isotope analyses do not support an obligate link between photosynthetic activity and heterotrophic subsidy with increasing depth. We found that A. lamarcki colonies at the bottom of the species depth range can be physiologically similar to those nearer the surface. As a potential explanation, we hypothesize sites with high topographical complexity, and therefore varied microhabitats, may provide more physiological niches distributed across a larger depth range. Varied microhabitats with depth may reduce the dominance of depth as a physiological determinant. Thus, A. lamarcki may ‘avoid’ changes in environment with depth, by instead existing in a subset of favourable niches. Our observations correlate with site-specific depth ranges, advocating for linking physiology and abiotic profiles when defining the distribution of mesophotic taxa.

From experiments in the sea with wire cages and boxes with perforated zinc sides and tops more than 100 individuals of certain Crustacea which had grown inside the apparatus have been obtained at various subsequent dates.

Minimal mean rates of growth are obtainable from the difference between maximum size at immediate entry and size at a given later date, and the approximate age by an allowance for age at entry plus the maximum time occupiable in the experimental apparatus. It was found that C. maenas spawned early in the year may attain a carapace width of 30 to 40 mm. by the following winter. In experiments extending over twelve months from July to July male C. maenas attained a carapace width of 43 to 53 mm. and females 37 mm. at an estimated maximum age of 15 months.

This work is the outcome of an undertaking by the Mechanical Engineering Department to repair and if possible to improve a grab used by the Marine Laboratory. The grab was a type which has a good record of effective sampling on coarse hard sediment as reported by Smith & McIntyre (1954) and fully confirmed by our own experience. Its success in these difficult sediments is believed to be due to the initial penetration provided by the spring-propelled jaws and to adequate weight opposing the upward forces as the lifting cable closes them. Because of wear in the cocking mechanism the machine in question had become dangerous to operate and a number of parts had fractured. Improvements to the cocking/triggering mechanism were successful but it was felt that the repaired striking motion would remain prone to further failure by fatigue and wear. A fair degree of mechanical insight was necessary for effective operation and it was considered fairly laborious to use continuously, so the basic problem was reviewed from an engineering design standpoint with attention to the ergonomic and mechanical problems of achieving a quick turnaround in a small boat such as the laboratory's 10 m coble, and to ensuring durability.

Fish are perhaps one of the most highly parasitized of animal groups, and the unnatural crowding which occurs in hatcheries and aquaria favours the greatly increased possibility of heavy infestation by some parasites. Such hazards have been recognised in freshwater fishes for some time (see, for example, Dogiel, Petrushevski & Polyanski, 1961), and diseases of marine fishes are now beginning to receive increasing attention (Sindermann, 1966).

This note examines the way the pharyngeal feeding filter is constructed within the salp endostyle. Three salp species (Pegea confoederata, Thalia democratica and Salpa fusiformis) have been examined: results from each are essentially similar. The endostyle is a deep ventral groove in the pharynx, divided by a line of long basal cilia. These are flanked by gland cells which secrete the ‘mucus” which forms one of the sets of filaments of the filter. Beside the openings of this basal row of gland cells (marked by bumps of curious ‘mucus’ rodlets), there is a fence of two adjacent rows of cilia. The first of these two rows, (nearest the basal mid-line), whose tips lie next to the rodlet bumps, are regularly spaced 1.0 μm apart along the endostyle, whilst the cilia of the second row are at around half this spacing. Passing upwards in the endostylar groove, this first ciliary fence is followed by a ciliated zone, and then a second row of glandular cells is linked to a second ciliary fence with a single row of cilia only.

Filaments derived from the first set of gland cells pass obliquely over the ciliated zone, and continue over the second ciliary fence. The cilia of the second fence are often surrounded by very striking borders or curtains of rodlets which appear to dissolve, run down the cilia and pass off the tips as filaments, when they are joined by the first set of filaments to form a net with an elongate rhomboidal mesh. As this passes upwards, the mesh changes to become more or less square by the time it comes to overlie a striking asymmetrical band of cilia arranged in columns, when it is now composed of two sets of filaments running vertically and horizontally, spaced some 1.3 μm apart.

Various aspects of the formation of this filter net are considered.

The dogfish eggcase protects the developing embryo for up to a year against predation and fouling. The mechanical protection is provided by the strength and resilience of the case. The aim of this study was to determine the mechanisms underlying the case's antifouling proficiency. The eggcase is constructed of oxidatively cross-linked proteins, which are primarily collagen. Two main hypotheses were examined, firstly that the egg case scavenges heavy metals and these act as deterrents. Secondly, the tanning agents, particularly dihydroxyquinones, through reaction with Fe2+, produce hydroxy radicals that act as deterrents. This process is called the Fenton reaction. Using ten different species of marine bacteria, Semibalanus cyprids and Enteromorpha zoospores, a variety of experiments were conducted to examine the effect of surface chelation, iron loading, changing the surface roughness, different collagen types and quinones, and the presence of antioxidants. The results suggest that the photoactivated generation of free radicals is partially responsible for the antifouling mechanism of the eggcase. Collagen and quinone chemistry and surface integrity are also considered to be important in the antifouling process.

Although oogenesis is the best-known stage of development in sponges of the subclass Calcinea (Porifera, Calcarea), several aspects of this process await further investigation. In the present study, we examined by light and electron microscopy the oogenesis of three species of the order Clathrinida (Clathrina aurea, Borojevia aspina and B. brasiliensis) from the coast of Rio de Janeiro state (Brazil). Oogenesis in these species was a rare and not synchronized event, neither in the individual nor in the population level. Oocytes grew between the choanoderm and the pinacoderm. They did not form any special structure for nourishing the egg and phagocytosis of somatic cells was not observed. The vitellogenesis of B. aspina and B. brasiliensis was performed in a mixed pathway, while in C. aurea it was not possible to observe the vitellogenesis. In the Borojevias, the surrounding choanocytes provided small clear vesicles at the same time that oocytes modified phagosomes to produce fibrous yolk inclusions. The phylogenetic character mapping analysis indicated that egg development in the mesohyl is the ancestral state for Calcinea, while the ancestral condition of the vitellogenesis is still uncertain.

Ontogenetic and seasonal variations in the diet were studied for a benthopelagic fish, the red cod Salilota australis (Pisces: Moridae) from the Falkland Islands shelf. The study revealed that small fish (<39 cm total length, TL) fed mainly on benthic gammarid amphipods, with squid Loligo gahi, Illex argentinus and the fish Patagonotothen spp. being of secondary importance. In medium sized fish (40–60 cm TL) the importance of fish in their diet increased, but benthic gammarid amphipods remained important, although their role decreased in the percentage by weight. Large fish (>61 cm TL) fed mainly upon Patagonotothen spp. which consisted of 90% by weight. Seasonal variations were analysed only for medium-sized fish. In February–June, S. australis fed mainly on benthic amphipods and Patagonotothen spp. In July–October, the squid Loligo gahi became the most common prey. In November–January benthic crustaceans reappeared in the diet, and Patagonotothen spp. became the most important prey item followed by benthic gammarid amphipods and the isopod Seriolis sp. The niche breadth was found to be similar in the different size groups (2·03–2·66), indicating that the fish fed on one to two abundant prey items in each group. The niche breadth of medium-sized fish varied seasonally reflecting the diversity of prey items utilized throughout the year.

The present study checks on the validity of the hypothesis that heterozygosity and the fluctuating asymmetry (FA), common measure of the developmental stability, are linked in populations of wild and cultured stocks of Sparus aurata from five countries. Muscle and liver samples were analysed for variation in 26 allozymes and three microsatellite loci. Pectoral fin rays and upper and lower gill rakers of the first branchial arch were counted on the left and on the right sides of each fish. Fluctuating asymmetry existed in the majority of the samples although their values were consistently low, (0·305±0·147), but higher in the cultured samples. The allozyme heterozygosity values were always high, but lower in the cultured samples. The microsatellite DNA analysis produced similar results. Heterozygosity was higher in cultured individuals (except for the Greek samples). These findings seem to be early evidence that the reared samples are losing some genetic variation, especially due to the loss of the rarest alleles (which were present in the wild populations). Genetic drift, probably caused by propagation practices, is most likely responsible for the decrease of the genetic variation. No distinct pattern of geographic separation was identified.

Developmental stages of a haemogregarine were found within polychromatocytes and erythrocytes in Giemsa-stained blood smears from six evileye pufferfish (Amblyrhynchotes honckenii) caught at Koppie Alleen in the De Hoop Nature Reserve, South Africa. This unusual haemogregarine, Haemogregarina (sensu lato) koppiensis sp. nov., was characterized by encapsulated gamonts with recurved tails, features more common in haemogregarines infecting amphibian and reptilian erythrocytes than in those from fish. Haemogregarina koppiensis is only the third species of fish haemogregarine to have been described from South Africa.

In the present work we describe nine saccular otolith morphometric indices (circularity, rectangularity, aspect ratio, percentage of the otolith surface occupied by the sulcus, percentage of the sulcus length occupied by the cauda length and ostium length, otolith length relative to the length of the fish, rostrum aspect ratio and percentage of the rostrum length occupied by the otolith length) of 41 species of the Tripterygiidae family collected mainly from New Zealand, Australia, Chile, South Africa, Mediterranean Sea and North America. The principal component of analysis showed that the indices that best explain the variability between species were related to sulcus and rostrum morphometry. According to cluster analysis, otolith morphometry could reflect the diversity of microenvironments for some genera such as Notoclinops and Forsterygion, while this does not happen to genera like Enneapterygius and Ruanoho. The discriminant analysis showed that the species Helcogrammoides cunninghami, Karalepis stewarti, Lepidoblennius haplodactylus, Notoclinus compressus, Ucla xenogrammus can be discriminated by using the morphometric indices. Two new indices related to the sulcus that were of great value for the discrimination of these species are described for the first time. This information will be a useful tool for palaeontological, taxonomic and trophic ecology studies.

We examined the distribution, hatch-date, growth, and mortality of larval Benthosema pterotum, a dominant pseudoceanic myctophid in the shelf region of the East China Sea, during early autumn when the main spawning has been predicted. This species is a key species in the food web of this area. Larvae were abundant in the area south of Cheju Island (60–80 m depth), corresponding with the adult habitat. Occurrence of the larvae was restricted to the onshore side of the shelf-break salinity front, indicating that this front acted as a barrier restricting the offshore dispersion of the larvae. In the area where the larvae occurred, a cyclonic eddy is formed, which is considered to limit the dispersal of the larvae, enabling them to recruit into the area of adult habitat. Modes of hatch-date appeared from late August to early September and from mid to late September, suggesting that large-scale spawning events occurred at least twice during the spawning season. Since the modes coincided with the new moon period, B. pterotum is suggested to spawn periodically once a month around the new moon, resulting in efficient mating and fertilization. Mean absolute growth rate (0.26 mm d−1) and weight-specific growth rate (18.8% of dry body weight d−1) were higher than previously reported values of other subtropical–tropical myctophids, which would be related to the high food availability in the study area. Daily instantaneous mortality coefficient during the first two weeks after hatching was estimated to be 0.28 d−1 (equivalent to 24.7% mortality d−1).

Artificial reefs (ARs) are often used to improve fishing and, consequently, the economy of a region. However, the way in which the species use the reefs may vary between fish assemblages. An assessment was made of the influence of an AR complex on the transient fish population off the northern coast of Rio de Janeiro state and, therefore, two control areas were sampled. Gillnets were used to capture individual fish in six sampling surveys. Cumulative abundance and biomass curves (ABC) were used to assess the possible effects of the reefs on the community's functional structure. In the dry season, during which the influence of the Paraíba do Sul River is smaller, a larger richness of r-strategy species and juveniles of K-strategy species was observed in the reef area compared with the control areas, suggesting that the AR acts as a protective environment for these species. During the lower river discharge period the results indicated a potential disturbance in the functional structure of the AR fish community and, therefore, a less stable environment relative to the control areas. This ‘instability’ warrants a positive connotation, as it indicates that the artificial reefs are harbouring species that are particularly sensitive to predation, making the reef a powerful tool for maintaining these populations on the northern coast of Rio de Janeiro.

Dynamics of the Abra alba muddy fine sand community of the Rance Basin (western English Channel), initially sampled in one station by Retière at the beginning of the 1970s after the tidal power station built at the mouth of the estuary went into service, was reassessed from 1995 to 1997. Results showed a more ‘mature’ community in 1995–1997 with an increase in the number of species. After a short period, in spring 1995, during which the structure of the community was comparable to those described in 1972–1973, the assemblage was characterized by a great interannual structural stability. Densities of dominant species seem to fluctuate around a mean value comparable to the carrying capacity of the biota for these species. The recruitment of the dominant species with a long life span appears low compared to the densities of adults but seems sufficient to assure the replacement of individuals. Our results suggest that the pattern of massive recruitment followed by high mortality rates could not be the general rule and that a pattern of moderate recruitment followed by low post-settlement mortality of recruits should be more frequent.

Tissues from a number of marine species were treated with a variety of solutions, including 1% of the major ‘detergent’ (B.P. 1002) used in attempting to disperse the oil from the ‘Torrey Canyon’ and 1% of each of the three major constituents of B.P. 1002, two of which are non-ionic surfactants.

The extracts were submitted to vertical starch-gel electrophoresis in order to measure both the effect of the detergent in facilitating the breakdown of cellular structure (extractability), and the irreversible effect on activation or inhibition of various enzymes and other proteins.

The proteins studied include a variety of NAD- and NADP-linked dehydrogenases, esterases, blood and nerve haemoglobins, plasma proteins, egg white and yolk proteins, and r-phycoerythrin.

The results confirm the general opinion that detergents increase the extractability of proteins from cells. In particular lipoprotein systems are altered, e.g. ‘fast’ serum lipoprotein in fishes (and other vertebrates). Other effects are also observed, e.g. sole but not turbot haemoglobin is rendered relatively insoluble, probably because the detergent stabilizes haemoglobin binding to other components in the erythrocyte. Certain enzymes, e.g. some esterases and amylases, are activated—a not surprising observation. However, a few enzymes are altered in electrophoretic mobility or in activity in a way that one might not expect, e.g. bass Morone labrax lactate dehydrogenase.

The results indicate that ‘oil-spill’ detergents and their constituent surfactants are biochemically quite powerful agents. It is too early to attempt to correlate in vitro and in vivo observations but there is an indication that starch-gel electrophoresis provides a useful supplement to more conventional methods used in the studies on complex pollution problems.