Temporal and spatial fluctuations of environmental parameters are normally assigned as causes of variations in morpho-phenological characters of seaweeds and in their epibionts, but formal tests of such hypotheses are lacking, especially in narrow gradients. The present study evaluated the influence of a very small depth gradient (1 to 3 m) and of subtle seasonality characteristic of tropical areas on morpho-phenological traits and on the occurrence of sessile epiphytic organisms using a controlled orthogonal sampling design in a sublittoral population of the tropical brown alga Sargassum cymosum. Four temporal samples were obtained over a one-year period at three depths using nine replicates. The wet weight, maximum length, number of primary and secondary branches, and proportion of secondary branches with receptacles were recorded. Epibiosis was estimated by visual evaluation of percentage cover on secondary branches. Algal morphology varied as a function of the period of the year (weaker effect) and depth (stronger effect) but in different ways for each variable analysed. In general, fronds tended to be shorter, heavier, and more ramified in shallower areas. In relation to time, the morphological characters tended mostly to present higher values in January (summer) and/or April (autumn). Frequency of receptacles did not depend on algal morphology and depth at all but varied in time, although only in the deepest area. Epibiosis also did not depend on algal morphology but varied in relation to time (stronger effect) and, to a lesser extent, depth (weaker effect). The effect of time upon epibiosis also depended on the biological group analysed. These data support the hypothesis that algal morphology varies in relation to period of the year and depth, even under small temporal and spatial environmenal gradients.

This study was implemented to determine the environmental factors and causative organisms of the recent mucilage formation in the Marmara Sea. Samples were taken during the study from 7 different depths (0.5–30 m) of one sampling point of the Büyükada Island shore between January and June 2008. As a result, 62 phytoplankton species belonging to 5 different groups were identified. Dinoflagellates were dominant in terms of species number, and diatoms in terms of cell number. In January and February, mucilage formation was very dense, where 5 phytoplankton species (Clindrotheca closterium, Pseudo-nitzschia sp., Skeletonema costatum, Thalassiosira rotula (Bacillariophyceae) and Gonyaulax fragilis (Dinophyceae)) were reported as dominant organisms. Among them, Gonyaulax fragilis has never been reported in the Marmara Sea previously, thus that organism appeared firstly with the formation of dense mucilage and then when the mucilage decayed in May and June 2008, G. fragilis disappeared. Autofluorescent single-celled organisms were classified in three groups depending on their cell sizes (>20 μm, >2 μm, >0.2 μm) by membrane filtration and total count of bacteria were determined by epifluorescence microscope after dying with DAPI. The highest total bacteria was recorded in April at 25 m depth (6655 ± 44.4 cells ml−1) while the lowest count was in June at 0.5 m depth (1077 ± 26.1 cells ml−1). The seawater temperature ranged between 7.0 and 21.5°C, salinity between 20.9 and 37.4 ppt and dissolved oxygen amount between 2.75 and 12.75 mg l−1. The chlorophyll-a amount ranged between 0.10 and 6.35 μg l−1, the higher values were recorded in January at 15 m depth (6.35 μg l−1) and in April at 10 m depth (4.89 μg l−1). Among the nutrients, the amounts of nitrite + nitrate-N varied between 0.02 and 7.67 μg-at N l−1, phosphate-P between 0.11 and 0.96 μg-at P l−1 and silicate-Si between 0.37 and 8.93 μg-at Si l−1. The highest values were determined at a deeper layer where nutrients are accumulated. On the other hand, the N:P ratio interval was found as 0.1–11.3, Si:P ratio as 2.92–52.33 and N:Si ratio as 0.01–1.10 during the sampling period. Nitrogen was the limiting nutrient and the silica amount was enough to enable the development of diatoms.

Two species of benthopelagic deep-water crustaceans, the suprabenthic mysid Boreomysis arctica and the bathypelagic euphausiid Nematoscelis megalops were analysed in their lipidic composition, with especial emphasis on fatty acids, from specimens obtained in the north-west of Mallorca (Balearic Islands, western Mediterranean) at depths ranging between 650 and 780 m. Temporal shifts were studied seasonally, based on five cruises performed in August and November 2003, and February, April and June 2004, using a Macer-GIROQ suprabenthic sledge (0.5 mm mesh size). Evidences of omnivorous and carnivorous feeding habits were found for both species derived from their fatty acid and other lipid profiles. Boreomysis arctica showed a more varied fatty acid profile than N. megalops. This suggests that B. arctica feeds on a wider range of food sources and is a more opportunistic feeder. The high proportions of 16:1(n-7), 20:5(n-3) and 22:6(n-3) fatty acids in both species suggests a link between surface primary production and deep slope habitats, while markers such as 18:1(n-9) and the 20:1(n-9) and 22:1(n-11) fatty alcohols indicate a predatory activity, likely on calanoids. These components may arrive both via phytodetritus deposition to the seabed and by migratory movements of prey consumed by B. arctica and N. megalops close to the sea bottom. Seasonal changes in the total lipids and fatty acid composition of both species are related to the seasonal dynamics in their food sources, coupled with changes in the physiological or developmental stage of individuals. The proportion of total lipids and polyunsaturated fatty acids in the two species may be related to the different life histories of B. arctica and N. megalops. The mysid has direct development of embryos within brood pouches, so eggs with large amount of vitelum are generated and gonad is well developed. By contrast, the meso-bathypelagic euphausiids generate planktotrophic larvae, with a high number of free developmental larvae stages (from nauplius to Furcilia/Calyptopis), and eggs with poor storage of lipid compounds compared with B. arctica embryos.

The genus Callinectes comprises seven species of blue crab found on the Brazilian coast, almost all are recorded in Cachoeira River estuary. The objective of this study is to analyse distribution of Callinectes species in the estuary of Cachoeira River (Ilhéus, Bahia). Monthly collections were conducted in the low tide of neap tide for a year and in five stations distributed according to the estuary salinity gradient. Six traps were assembled and submerged at each station for two hours. Sediment samples were collected for granulometric characterization and measuring of organic matter content. Temperature, salinity and pH were also measured in the bottom water, as well as water transparency at the start of each collection. Five species were collected: Callinectes danae, C. ornatus, C. exasperatus, C. larvatus and C. bocourti. The species presented different distribution patterns based on the salinity gradient and transversal profile of the estuary. Only C. danae was found in all collection points, and was the most abundant species throughout the study period. Callinectes ornatus was restricted to external estuarine areas, which presented higher salinity and transparency values. Callinectes larvatus predominantly occurred in the external station and estuary partitions, mainly in the margin. In spite of the occurrence of C. exasperatus throughout the entire estuary, this species was restricted to the margin. This study supports the assumption that species distribution patterns of this genus are the result of both variable influence, namely salinity, and complex intraspecific and interspecific relations between the congeneric species.

The structure of hitherto-unknown exocrine glands in the caudal rami of the pelagic copepods of the genus Calanus was investigated, together with the vertical, diel and seasonal variations in the occurrence of granules secreted from the glands. Zooplankton samples were collected in Sagami Bay by vertical tows of a net from 4 discrete layers at 250-m intervals in the upper 1000 m both day and night, with an additional seasonal sampling in the upper 200 m. The samples contained copepodids of Calanus sinicus (stages IV–VI), C. jashnovi (stages IV–V), and unidentified Calanus (stages I–III), which possessed the glands regardless of the developmental stage and sex. Each caudal ramus has an inner- and an outer gland each of which opens in a pore at the ventral base of a caudal seta. According to light microscopy the cavities of only the inner glands contained many transparent granules, some of which appeared to have been discharged to the environment. The granules were present regardless of day/night, depth, and season, with the maximum number of 52/copepod. The cells surrounding the inner cavity contained well-developed rough endoplasmic reticulum, mitochondria, Golgi-bodies, and secretory granules; the outer cavity contained granules of much lower density than those in the inner cavity. These observations rule out the possible functions of the glands for egg and sex pheromone production, and suggest most likely function is predator avoidance. However, neither has mechanical disturbance excited luminescence, nor has ultraviolet emission excited fluorescence, suggesting the secretion is non-luminescent. Alternative possible functions include secretion of defensive substances or substances that might enhance swarm formation. A survey of preserved copepod collections indicated presence of similar glands in Calanus helgolandicus, C. pacificus, Cosmocalanus darwinii, Mesocalanus tenuicornis, and Nannocalanus minor, suggesting evolution of the glands in the common ancestor of these species that comprise a monophyletic group within the Calanidae.

The jumbo squid Dosidicus gigas is the only ommastrephid commercially caught in Mexico. Despite the economic and ecological importance of this species, little is known about its early life stages. The relationship between the presence of paralarvae and mesoscale oceanic features was investigated for the first time in the central Gulf of California, Mexico in February, April, June and September of 2008. A total of 86 paralarvae were found only in June and September (summer season), in the well-stratified column water where the thermocline was evident and warm sea surface waters (27.7° to 29.4°C) dominated. The greatest abundance of D. gigas paralarvae was observed within 2.23 to 3.48 km of the main front. The mantle length of the smallest paralarvae corresponded with the mantle length at hatching. The San Pedro Mártir Island–Santa Rosalia transect and Santa Rosalia–Guaymas transect were determined as the main hatching localities in June and September respectively. The number of paralarvae found in this study contrast with the potential fecundity of mature females which are found throughout the year.

This study analyses the significance of shell morphological variations in the venerid clam Tawera gayi, a typical element of shallow marine soft bottoms in southern South America and the most common species recovered from Late Quaternary marine deposits along the Beagle Channel, Tierra del Fuego. Fossil and modern Tawera shells from different localities around the southern tip of South America were analysed using the Elliptic Fourier Analysis (EFA) method. Taking into account the palaeontological history of this genus in the southern hemisphere, EFA was also performed on shells of Tawera congeners from South Africa (T. philomela) and New Zealand (T. spissa). The use of EFA permitted the distinction between the three Tawera species and geographical differentiation in the T. gayi groups. These morphological variations of T. gayi appear best related to ecophenotypic plasticity as a response to different environmental conditions, although the palaeobiogeographical history of Tawera in South America cannot be ruled out.

A detailed account is given for the first time of the biological morphology of pinnid larvae taken from the north-west Atlantic. Three species were present in plankton samples taken from depths of 150–200 m. These were maintained in small aquaria and details of their anatomy, development and metamorphosis recorded and illustrated as far as the young adult stage.

Lophelia pertusa, a cosmopolitan cold-water coral, offers potential for new palaeoclimate proxies. This study investigated its skeletal growth patterns to aid in this development. Corallite characteristics (calyx diameter, height, thecal width and banding) of L. pertusa sampled from oil platforms in the northern North Sea were examined. The mean distance between daughter polyps along a growth axis (27.4 ± 5 mm, SD) was equivalent to the estimated annual growth rate; hence, the polyps bud once a year. The majority of growth occurred in the first year when the characteristic trumpet shape of a corallite was formed, while the thecal wall thickened more consistently. Further examination of two polyps showed a dark growth band and centres of calcification along the full length of the inner theca, which represents early skeletal growth. Skeletal sampling adjacent to this area along sequential polyps shows promise as an annual chronology in these North Sea corals.

Morphometric and gonad maturity of Libinia spinosa on the coast of Mar del Plata, Argentina, were assessed. In both sexes various morphometric features were measured to determine the morphometric maturity, and through macroscopic inspection of gonads and analysis of its content, different stages of gonad maturity were described and the physiological maturity was estimated. In females, the carapace width ranged from 8 to 56.5 mm while in males from 4.6 to 81.97 mm. The size at which 50% of females were morphometrically mature was calculated at 40.6 mm. Based on the allometric growth of the abdomen, two morphometric groups of females were recognized as juvenile and adult phases. In males, results of principal component analysis showed that the most suitable variables that efficiently represent the size and sexual differentiation factor were the carapace width and cheliped length respectively. The size at which 50% of males were morphometrically mature was estimated at 58.9 mm. Based on the allometry of the cheliped growth, two morphometric groups were recognized as immature and mature phases. Males maintained under laboratory conditions moulted and growth was related to regular and terminal moults. Males reached their terminal moult at a wide size-range, from 48.5 mm to 61.4 mm of carapace width. This terminal moult coincided with the size of morphometric maturity. In both sexes four stages of gonad development were described, two corresponded to immature phases and two to mature phases. The size at which 50% of females and males reached gonad maturity was LC50 = 40.33 mm and LC50 = 33.6 mm, respectively. In females, both morphometric and gonad maturity occurred at a similar size. In males, gonad maturity is acquired prior to morphometric maturity, thus three different types of males were characterized: (1) those with small carapace width and cheliped, without spermatophores in their vas deferens; (2) those with large carapace width and small cheliped, bearing spermatophores in their vas deferens; and (3) those with large carapace width and cheliped, bearing spermatophores in their vas deferens.

Larvae of eight sea spiders from three families (Ammotheidae, Pycnogonidae and Phoxichilidiidae) are described for the first time. The external morphology of the first larval stage of each species is presented in detail using scanning electron microscopy photographs in order to determine the mode of postembryonic development. Three types of larval development are apparent in the species examined. The species Achelia gracilipes, Eurycyde spinosa, Pycnogonum rickettsi and Pycnogonum stearnsi (families Ammotheidae and Pycnogonidae) have larval morphologies indicative of an ‘ectoparasitic’ development. Morphological characteristics of Achelia simplissima and Achelia chelata (family Ammotheidae) larvae suggest an ‘endoparasitic’ development, while larvae of the species Anoplodactylus viridintestinalis (family Phoxichilidiidae) have traits implying an ‘encysting’ postembryonic mode of development. Larvae of the species Nymphopsis spinosissima have unusual morphological characteristics that may be indicative of a new developmental mode.

Through rearing known age individuals and maintaining chemically marked adults in captivity, this study explored the rate of increment formation in southern calamary (Sepioteuthis australis) statoliths over seasonal (summer and winter) and ontogenetic (hatchlings and adults) extremes. A ‘one increment–one day’ relationship was verified for captive-reared hatchlings up to 40 days post-hatching which remained stable across the seasonal extremes. This relationship, however, was not evident in the chemically marked adults as inconsistencies of up to 44 days were detected between the number of days elapsed post-stain and the increment count. No seasonal effect was detected in the ratio between increment count and days elapsed, however, the degree of underestimation was consistently greater for winter-caught adults by approximately 2.5 increments relative to summer-caught adults. This less-than-daily increment formation in adults may be due to: (1) the periodicity of increment formation changing throughout the squid's lifespan; (2) deleterious effects associated with rearing squid in captivity; and/or (3) compromised interpretation of the statolith microstructure as a result of the preparation method.

To highlight the diversity of extracellular embryonic matrix (ECM) secreting structures in the gastrulae of the starfish Pisaster ochraceus the localization of antibody generated to hyaline layer, was studied. It was shown that hyaline layer epitope takes place in the cortical granules. Moreover, this material was revealed in secretory vacuoles and secretory vesicles which are situated in the apical parts of ectoderm cells. Besides, the same molecules were found in the yolk granules having loosened content. It seems likely that in P. ochraceus the ECM is secreted by four types of secretory structures.

The oilfish, Ruvettus pretiosus, is an incidental by-catch of the drifting surface longlines targeting swordfish and Thunnidae in the Mediterranean and elsewhere. Despite its global distribution and frequent occurrence in the catch of many fishing gears, little is known about its biology. In this study we examined the dietary preferences and reproductive biology of this species from specimens caught in the eastern Mediterranean. The most numerous and frequently occurring prey items were benthopelagic fish, followed by cephalopods. The sex-ratio was highly skewed in favour of females (1:8.4), while histological examination of the collected ovaries displayed six developmental stages (perinucleolar, early and late lipid stage; early, middle and late vitellogenesis). Oocyte diameter ranged from 23–69 μm at the perinucleolar stage to 224–366 μm at the late vitellogenesis stage. Spawning is expected to occur during mid and late summer; however there were no individuals available from this period. The findings are discussed in relation to the ecology of the species.

In altricial mammals, mothers' care and attendance are essential for young to acquire survival skills. Despite the crucial importance of this early period for pup survival, not much is known about mother–pup behaviour and time allocation in the wild. To improve our understanding of the critical period of the sea otter development, a total of 240 30-minute focal follows of females with pups of different ages were conducted in four 6-hour-periods (dawn, day, dusk and night) from 4 June to 12 August 2008. Generalized linear models were used to investigate the impact of age, weather, tide and time of day on otters' behaviour. Pups significantly decreased resting behaviour and increased feeding, travelling, interacting and grooming behaviour with increasing age. Females with large pups fed and interacted significantly more, and travelled and groomed the pup less than females with small pups. Foggy conditions were associated with less resting on the water and increased travelling by pups. Tide did not appear to have an effect on sea otter behaviour. Grooming by pups occurred mainly during dawn in medium sized pups whereas large pups groomed themselves mostly during the day and night. Variations due to times of day tended to be apparent only in larger, i.e. older pups. Females and large pups were more active during the day. Mothers of smaller pups spent most of their active time travelling whereas females with large pups were mostly feeding. This study showed how sea otter females with pups adapted their behaviours as their pups grew and matured during the first months of life.

The preference for two shell species, Monodonta labio form confusa and Thais clavigera, was compared between two populations of the hermit crab Pagurus filholi from Oura Bay, Shimoda, central Japan and from Hakodate Bay, Hakodate, northern Japan. Hermit crabs from Oura Bay preferred T. clavigera to M. labio form confusa, whereas crabs from Hakodate Bay preferred M. labio form confusa. The shell of T. clavigera was more effective against desiccation and high temperature stress but heavier than M. labio form confusa. The preference of P. filholi from Oura Bay for T. clavigera may be attributable to the greater requirement for protection against higher physical stresses, even though a higher energetic cost related to the shell weight is incurred.

An inventory of the main epibiont organisms on living specimens, on empty shells and on pagurized shells of Fusitriton magellanicus collected in Zygochlamys patagonica fishing grounds off Argentina is provided here. Additionally, considering that the presence of the thick, hairy periostracum could be an inhibitor of boring and encrusting species, we analyse the presence of a periostracum in living F. magellanicus in relation to the presence of epibionts. More than 70% of all shells bore encrusting organisms (of at least 30 taxa) but only a small proportion of shells was heavily fouled, the majority of living, empty and pagurized shells being lightly or moderately fouled. Polychaetes were the most common epibiont group (present on more than 60% of shells) while sponges and ascidians were responsible for the majority of the heavily fouled living gastropods. In general, specimens had a moderate level of encrustation and, simultaneously, a low or medium coating of periostracum. Hairy gastropods (only 14% of the sampled specimens) had few or no epibionts. A relationship between the size of the shell and the level of encrustation was only found in living gastropods. Fusitriton magellanicus is the second species in importance (after the Patagonian scallop) for the provision of a hard settlement substrate in the shelf-break frontal area of the Argentine Sea.

Metacercariae of various digenean trematodes are assumed to impair the burrowing capacity of cockles Cerastoderma edule. To reveal if metacercarial infections of the gymnophallid Meiogymnophallus minutus have effects on burrowing and shell closure, a laboratory experiment using cockles with slight and extremely heavy infections was performed at water temperatures of 15, 20, and 25°C. Gaping of the cockle shell valves or other behavioural abnormalities, which have previously been ascribed to M. minutus infections, were not observed. Neither response time nor burrowing time differed significantly between slightly and heavily infected cockles at any of the temperatures tested, suggesting that the effects of the digenean trematode on its second intermediate host are not necessarily as pronounced as proposed by earlier publications, not even when additional environmental stress in the form of high water temperatures is present. Our findings question the hypothesis that M. minutus manipulates the behaviour of C. edule, in order to increase the probability of successful transmission to the avian final host.

Digenean trematodes infecting the mud snail Hydrobia ulvae were studied at two key sites of the Mondego Estuary (Portugal), from January 1993 to September 1995: a mud flat covered by the seagrass Zostera noltii, and a bare sand flat where seasonal macroalgal blooms occurred as a result of eutrophication. Digeneans belonging to Microphallidae, Notocotylidae, Haploporidae and Heterophyidae were recorded in snails from both sites whereas representatives from Echinostomatidae were only found in snails from the seagrass bed. The density of infected snails was higher at the seagrass bed than at the eutrophic area partly reflecting the difference in population structure of H. ulvae between sites. The Zostera noltii bed supports an abundant and well-structured mud snail population, with all size-classes represented, in contrast to a less abundant and juvenile dominated population in the eutrophic area. In the Z. noltii bed no clear seasonal and interannual patterns emerged in the infection densities. In the eutrophic area, the density of infected individuals increased in the presence of algae, and decreased during the occurrence of occasional flood events. Small scale spatial and temporal patterns in the prevalence of digenean trematodes in mud snails were therefore demonstrated within the Mondego Estuary that has experienced a mixture of anthropogenic impact and climate instability.

The edible cockle Cerastoderma edule is one of the most common soft sediment bivalves in Europe and of commercial relevance in some areas of its range. Information on the parasite fauna of cockles is available from several North Sea and Atlantic shore locations. However, little is known from the British Isles in this context. This study provides an inventory of the macroparasites of C. edule sampled from fourteen localities along the south coast of Ireland. Altogether, we identified ten taxa of macroparasites belonging to three major groups. The majority of them were digenean trematodes using cockles as second intermediate host. Infection rates and levels were comparatively low, with the exception of the gymnophallid Meiogymnophallus minutus, which was found to be prevalent at all sampling sites and often very abundant. Whilst parasite species composition in Irish cockles was similar to the one found in conspecifics from northern Europe, it showed distinct differences from the macroparasite fauna reported from C. edule collected in southern Europe and northern Africa.