Evaluating the ecological impact of an oil spill is a complex issue requiring coherently articulated examination of the sequence of interactions that link the cell, where contaminants exert their effects, to the ecosystem, where interactions with human activities arise. This sequence of interactions traverses the frontiers between scientific disciplines (chemistry, toxicology, physiology, and fisheries ecology). Using the common sole (Solea solea L.) as a model species for the coastal habitats polluted by the “Erika” oil spill, our research project attempted to define indices of functional integrity that characterised the consequences of fuel exposure at the different biological levels. The coupling of field observations with experimental laboratory work revealed how functional alterations which are readily observable within individuals and their organs are progressively obscured as investigation progresses towards more complex organisational levels. Some of the approaches and indices are proposed as instruments for evaluating the impact of contamination by hydrocarbons.

Despite its wide use in terrestrial ecology, distance sampling is as yet rarely used in underwater visual censuses. The present study attempts to compare density estimators based on distance sampling and on strip transects. Three stations with increasing densities of Chaetodontidae and Pomacanthidae were sampled twice by two divers of unequal experience, using two different transect types. A total of 96 transects and 2970 records of Chaetodontidae and Pomacanthidae were analysed. Nine estimators based on distance sampling were calculated and only the best fit (DT estimator) was kept for comparison with other estimators. These were either based on the average distance of the fish to the transect (AD estimator), or a 3-m- or 5-m-wide strip transect estimator (FW3 and FW5, respectively). There were no significant differences between the means found by DT, AD and FW3. Lower density estimates were given by FW5 in all cases. FW3 and FW5 did not detect several significant differences between stations which were otherwise detected by DT or AD. The number of transects needed to detect a significant difference between stations was four to ten times higher with FW3 or FW5 than with DT or AD. Diver experience was found to be a significant factor in density estimates. However, this factor was less important than the choice of the density estimator. Transect type or the day of sampling had no consequence for the estimates. The distance distributions of fish were divided into three different patterns which may be explained by a combination of detectability function and a behavioural component.

The fisheries of Lake Victoria in East Africa must be managed effectively to ensure sustainable food supplies. This has been impossible in the past due to inadequate knowledge of commercially important fish stocks. Here we present the first acoustic abundance estimates of fish in Lake Victoria. Five lakewide acoustic surveys were conducted between 1999 and 2001, using the Simrad EY500 echo-integrator with a 120 kHz split-beam transducer. There are many species of fish in Lake Victoria, however, only limited identification of targets can be achieved by present methods. Broad categories were distinguished by visual examination of echo-traces. The echo-integrals were partitioned between four target groups: (1) the Nile perch (Lates niloticus), a top predator, (2) small pelagics comprising mainly the dagaa Rastrineobola argentea together with mixed species of haplochromines, (3) the crustacean Caridina nilotica and (4) other species. Spatial and temporal differences in the Standing Crop were observed between north and south, and between shallow and deep water. Most fish were found inshore but the spatial distribution varied between seasons. Mid-lake fish densities were higher in August compared to February. In August, the water column is well mixed while in February it is stratified with a low-oxygen layer inhospitable to fish near the bottom. There are consequent changes in the characteristics of observed echo-traces. Over the survey series, Nile perch biomass showed a consistent decline, while the stocks of small pelagic species increased. We emphasize the need for simple rules to identify species, and hydrographic monitoring to assist echo-trace classification. In the absence of any other source of comprehensive biomass estimates, the value of acoustic surveying in Lake Victoria is demonstrated.

The fishery for Antarctic krill has been stable for a decade with approximately 100 000 tonnes being caught each year. There is continuing commercial interest in products derived from krill. An examination of patent databases indicates that the development of products for human consumption has been overtaken by the development of aquaculture, pharmaceutical and medical products. The development of products for aquaculture is most likely to be the factor that will drive growth in the krill fishing industry. Management of the Antarctic krill fishery has proceeded in advance of expansion and precautionary catch limits for Antarctic krill currently total 4.89 million tonnes ~50 times the existing harvesting level.

Our understanding of the microcell oyster parasites of the genera Bonamia and Mikrocytos has expanded in recent years with the application of ultrastructural and especially molecular biological research approaches. Molecular phylogenetic analyses of SSU rRNA genes have united three species, Bonamiaostreae, Bonamiaexitiosa, and Mikrocytos (now Bonamia) roughleyi, in a microcell clade within the Haplosporidia, supporting both early and recent ultrastructural observations. Ultrastructural and molecular phylogenetic evidence has emerged that Mikrocytos mackini, on the other hand, is a unique protist with unusual adaptations for a parasitic existence. DNA probes and polymerase chain reaction (PCR) assays promise new insights into the life cycles, transmission, and diversity of these organisms. The development of Ostrea edulis lines selected for B. ostreae resistance will increase the viability of aquaculture industries for this species and, combined with rapidly developing biotechnological approaches for studying host defenses and host-parasite interactions, will allow greater insight into the nature of phenomena such as resistance and tolerance to disease in oysters.

This paper presents a comprehensive study of the impact of damming on the spawning migrations of Barbus barbus in the canalized River Meuse (Southern Belgium). A Denil fish pass on the Ampsin-Neuville dam was controlled 251 times in 1989-1993. The most striking feature is the almost complete absence of barbel in 1990-1993 (15 fishes in 4 years). Most captures of barbel in the fish pass in 1989 were clumped within a few days (mid-May) and related with spawning migrations. Stepwise multiple regression analyses revealed that attractivity was the major condition set allowing barbel to migrate successfully through the pass, while feasibility parameters (water velocity) were found not to be relevant. The variables involved in the attractivity condition set refer indirectly to the influence of water catchment by a hydroelectric plant and to the relative importance of the flow in the pass. The study concludes that this additional condition set significantly interferes with the natural environmental stimuli triggering spawning migrations in barbel and questions the effectiveness of the thermally-related reproductive strategy of the species in an environment with restricted longitudinal connectivity. This statement is discussed in parallel with the recent evolution of barbel populations in canalized rivers.

Rainbow trout juveniles (Oncorhynchus mykiss) were fed diets containing high levels (50, 70 or 100%) of vegetable proteins for 8 weeks. Vegetable protein sources employed were soybean meal, lupin seed meal and corn gluten meal, as well as potato protein concentrate. Nutritional evaluation showed that diets containing 50 or 70% plant protein supported growth rates, fish acceptance and nutritive utilization similar to those of both a whole fish meal diet and a commercial trout feed. A taste panel proved that organoleptic properties of fish were not affected by feeding on diets containing high levels of vegetable feedstuffs.

The first internal transcribed spacer (ITS-1) of nuclear ribosomal DNA and mitochondrial DNA 16S rRNA were amplified by Polymerase chain reaction (PCR) using genomic DNA extracted from adult tissue of four species of Scylla spp. and the first zoeal stages of S. serrata, S. paramamosain and S. olivacea as template. Using the ITS-1 region, variation in product fragment length was found to be useful for distinguishing S. serrata and S. olivacea from two other species. The other two species (S. paramamosain and S. tranquebarica) could be identified using the restriction endonuclease Hha I. Using 16S rDNA, all four species were identified using PCR-restriction fragment length polymorphism (RFLP) by double digestion with DraI and HindIII. These genetic markers can be used for hybridization breeding studies and in field studies of larval and juvenile mud crabs of the genus Scylla.

The toxicity of five cryoprotectants – methanol, DMSO, glycerol, ethanediol and sucrose – on different development stages of zebrafish embryos was investigated. Embryos were exposed to a range of cryoprotectant concentrations for 30 min at room temperature. Post-heart beat stage embryos were more resistant to cryoprotectants than carly embryonic stages. The maximum non-toxic concentrations of cryoprotectants on heart beat stage embryos were 2 M methanol, 2 M DMSO, 1 M glycerol, 2 M ethanediol and 0.5 M sucrose. Gradual stepwise addition did not reduce toxicity. Heart beat stage embryos survived 2 M methanol at room temperature for up to 5 hours, whilst DMSO and ethanediol were toxic after 3 and 1 hour exposure respectively. The effect of the nature and concentration of cryoprotectant, equilibrium time, and cooling rate were investigated during cooling to –30 °C. Methanol was more effective than either DMSO or ethanediol for zebrafish embryo cryopreservation and 0.3 °C/min was found to be the optimum cooling rate. Two-step addition of cryoprotectants, with the higher concentration of cryoprotectants added at 0 °C, improved the results. The best embryo survivals obtained after cooling were 94% at – 10 °C, 72% at – 15 °C, 43% at –20 °C, and 8% at –25 °C, no embryos hatched following cooling to –30 °C. Ice formation within the egg was found to be the main factor affecting survival of the embryos.

Yellowfin tuna (Thunnus albacares) are known to preferentially occupy the surface mixed layer above the thermocline and it has been suggested that they are physiologically restricted to water temperatures no more than 8 °C colder than surface waters. However, we here report for dive data acquired from a large yellowfin tuna which demonstrate for the first time that this species is indeed capable of making prolonged dives into deep cold waters. A yellowfin tuna (134 cm fork length) caught near an anchored fish aggregating device (FAD) in the Seychelles (Western Indian Ocean) was equipped with an internally implanted archival tag and released. The fish was recaptured 98 days later. As predicted for this species, this fish spent 85% of its time shallower than 75 m (maximum thermocline depth experienced by the fish) but, over the course of the track, it performed three deep dives to 578 m, 982 m and 1160 m. Minimum ambient water temperatures recorded at these depths were 8.6 °C, 7.4 °C and 5.8 °C respectively and varied by up to 23.3 °C from surface temperatures. The fish spent 8.3% of its time in waters more than 8 °C colder than the surface layer and daily experienced a wide range of sea temperatures (mode at 15-16 °C) and of temperatures of the gut cavity (mode at 6 °C). The reason for these dives can not be known. These depths and temperatures significantly exceed those reported in the literature so far and clearly demonstrate that this species has the physiological and behavioral ability to penetrate deep cold sections of the ocean.

Seagrass meadows support high biodiversity and are important for invertebrate harvesting activities in developing countries. The aim of this study was to estimate the social and ecological effects of invertebrate harvesting, i.e. how this exploitation may affect/has affected seagrass variables (biomass, shoot density and canopy height), macrofaunal community structure, the use and importance of these resources for the livelihood of local people over time. A multi-disciplinary approach was used, including interviews with harvesters, observations of the number/activities of invertebrate harvesters, and a biological field study in Zanzibar, Tanzania. The study showed that women/children harvest invertebrates, and they prefer large seagrass patches, high to medium shoot density, and high seagrass cover. All interviewees said they had noticed a decline in seagrass distribution over the last decade,  >20% considered it a large decline. Interviewees also reported decreased numbers of animals, but no change in the number of animal species over the last decade. The main reasons for the decline of seagrass and animals according to interviewees, are an increase in the number of harvesters, and a change in attitude, i.e. people being less careful about the intertidal zone and seagrasses. Invertebrate harvesting was found important for food security and provision of cash income. The current average catch weight was ca. 2 kg/collection day/person, and 3 kg and 5 kg, 5–10 and 30 years ago respectively according to interviewees. At present, the harvesting women earn ca 60–70% and ca 40% of what they would have if catches were the same sizes as they were 5–10 and 30 years ago respectively, according to our calculations. The field sampling within seagrass beds showed that an inaccessible/remote site had significantly higher invertebrate abundance and species richness/diversity than an exploited site (ANOVA). Multivariate statistics further revealed weak but significant differences for animal abundance and biomass between these sites. By combining findings from both interviews and field sampling this study shows that invertebrate harvesters can influence macrofaunal community structure in seagrass meadows, which in turn results in negative impacts on local harvesters’ economy and livelihood.

The pressures on the use of the seashore are steadily rising, not only in developed countries but worldwide. Anthropogenic activity has long impacted the marine continental shelf down to a depth of approximately –200 m. New activities are now affecting this coastal space such as renewable energies, recreational uses and aquaculture in addition to the traditional ones of navigation or fishing. This evolution raises new sources of conflict amongst users which can require state involvement in order to manage the different stakeholders and pressure groups. However, the coastal space still offers a large potential for development for two reasons. Firstly, the physical three dimensional potential of this space enables the whole water column to be used, principally to increase the fishing productivity as in Japan. Secondly, innovative synergies can be created between socio-technical and ecological uses (a “fourth dimension”) such as the eco-design of wind turbine foundations in order to create fish habitat or sea grass settlement. This new vision in “4D” for the design and the management of coastal infrastructure can potentially reduce the risk of conflict as different uses of the coastal space would not necessarily exclude one another. Indeed, several forms of synergy could be developed such as fisheries with aquaculture or biological sustainability with social acceptability. Until now, limited attempts at such an approach have been done. We suggest this is likely due to the absence of a common eco-engineering vision and the lack of experience amongst biologists and engineers in the co-construction of projects. This eco-engineering, or “green” vision, also takes into account the complexity and resilience of the ecosystem in the long term, if underwater engineered infrastructures are also “eco”-designed to increase ecological gain This new conception, for development within the coastal area, provides for an increased bio-oriented complexity to engineered structure and therefore a better resistance of the ecosystem in the long term to anthropogenic pressures and a reduction in multi-user conflicts.

Habitat utilisation by juveniles of 13 commercially important fish species was studied in five habitats located in Chwaka Bay, Zanzibar: mangrove creeks, mangrove channel, sand/mud flats, a seagrass area close to mangroves, and a seagrass area far from mangroves. Fish samples were collected from each habitat using a seine net, and fish abundance and size were measured to determine habitat utilisation. The seagrass beds near to mangroves showed the most diverse fish assemblage of all habitats, possibly because it functions as a corridor between the mangroves and deeper parts of the embayment. Juveniles of Cheilio inermis, Hipposcarus harid,Leptoscarus vaigiensis, and Scolopsis ghanam inhabited seagrass beds only. Juveniles of Gerres filamentosus and Monodactylus argenteus were mainly found in the mangrove habitats. Lethrinus variegatus, Pelates quadrilineatus and Siganus sutor were found in more than two habitats, with highest abundances in seagrass beds. Juveniles of Gerres oyena, Lethrinus lentjan, Lutjanus fulviflamma and Sphyraena barracuda were the most generalist species and were found in all studied embayment habitats. Visual census surveys supported the seine net data showing that most fishes in the embayment habitats were juveniles or sub-adults. In terms of habitat utilisation by different size classes, five of the 13 species (Lethrinus lentjan, L. variegatus, P. quadrilineatus, Siganus sutor and Sphyraena barracuda) were found as small-sized individuals in shallow and turbid mangrove areas, whereas large-sized individuals were observed in deeper and less turbid seagrass beds. A possible explanation for this pattern could be an ontogenetic shift in habitat utilisation, although this could not be proven. The patterns observed in the present study show a high similarity to those observed in marine embayments in the Caribbean, indicating that similar mechanisms are at work which make these systems attractive juvenile habitats.

Sixteen silver eels (Anguilla anguilla L.) were tagged with pressure-sensing ultrasonic transmitters and tracked for 1 to 152 hours, 12 in the western Mediterranean and 4, treated with pituitary extracts, in the Sargasso Sea. When released on the shelf of the Mediterranean near Gibraltar the eels preferred a course which led them continuously to deeper water. Four specimens released on the Morrocan shelf, reached depths of 350 m, continued to swim north or changed their earlier easterly course towards the north. Three eels in the Sargasso Sea showed progress in a southwesterly direction. No influence of tidal stream on the swimming course and speed is obvious except for one eel, released in the Straits of Gibraltar. In the Mediterranean, the eels exhibited conspicuous daily vertical migration downward during dusk and upward during dawn with a mean swimming depth of 196 m during darkness, 344 m during daylight. Depth preference during night probably varied with the phase of the moon. Maximum swimming depth near Gibraltar as well as in the Sargasso Sea was nearly 700 m. The eels in the Mediterranean swam at a mean speed of 0.3 m.s−1 and were slower than most eels tracked in northern waters. Differences in the speed and in the directed swimming in the course of the lunar or the solar day are visible.

Individual Pinctada margaritifera molluscs were collected from the Takapoto atoll (Tuamotu Archipelago, French Polynesia) and used to produce ten first generation full-sib families in a hatchery system, following artificial breeding protocols. After three years of culture, these progenies were transferred to Rangiroa atoll (Tuamotu Archipelago, French Polynesia) and tested for their potential as graft donors. A large-scale grafting experiment of 1500 grafts was conducted, in which a single professional grafter used ten individual donor oysters from each of the ten families, grafting 15 recipient oysters from each donor. The recipient oysters were all obtained from wild spat collection in Ahe (Tuamotu Archipelago, French Polynesia). After 18 months of culture, 874 pearls were harvested. Highly significant donor family effects were found for nucleus retention, nacre thickness, nacre weight, pearl colour darkness and visually-perceived colour (bodycolor and overtone), pearl shape categories, surface defects and lustre, the last two of which are components of the Tahitian classification grade. No significant difference was recorded between the ten G1 families for the absence or presence of rings. The progenies could be ranked from “best” (i.e., the donor whose grafts produced the greatest number of grade A pearls) to the “worst”. Some progenies had extreme characteristics: family B presented the greatest number of pearls with lustre (98%) and a high proportion of dark gray to black with green overtone pearls (70%). These results have important implications for the selective breeding of donor pearl oysters: it may be possible to reach a point where specific donor lines whose grafts produce pearls with specific quality traits could be identified and maintained as specific breeding lines.

Specimens belonging to 20 species (7 families) of catfishes have been collected in French Guyana. The anatomy and histology of the male reproductive tracts have been studied. In the most primitivespecies (Helogeneidae, Ariidae) no seminal vesicle is present in the males. In the Pimelodidae,Loricariidae and Callichthyidae (and also in an african Bagridae), there is a progressive transition, going from anterior to posterior in the male tract, from testicular tissue towards round germ cell-free tubules and finally to seminal vesicular tissue. All these families produce round-headed spermatozoa and have external fertilization. The Auchenipteridae and Ageneiosidae are characterized by elongated sperm nuclei, internal fertilization with the aid of a gonopodium and sperm storage in the ovaries. In the Auchenipteridae there is a clear-cut distinction between testes and seminal vesicles. In the Ageneiosidae there is no seminal vesicle, but the dilated deferent duct displays a high secretory activity. Depending on the family and species, the seminal vesicles may carry out either one or both of the two main functions: secretion and sperm storage. In addition, in some species, sperm is also stored in one or two accessory pouches until fertilization. The trends that we have observed in the changes in the organization of the reproductive tracts are in agreement with the hypotheses proposed for catfish evolution from comparative anatomical data.

We analyzed the small-scale fishery in the port of Vilanova i la Geltrú (NWMediterranean) to assess the fishing practices in this fishery and produce economicindicators of its status. We defined the fishing tactics (or métiers) of this fishery witha multivariate analysis approach for evaluating the main fishery resources and fishinggears employed. Our results show that netters in this fishery practice 7 types of fishingtactics. Five of these fishing tactics, in terms of target species, gear and seasonality,are also used in other small-scale Mediterranean fisheries. The main types of fishing gear(trammel nets, gillnets) and target species (Sepia officinalis,Solea vulgaris, Mullus surmuletus andMerluccius merluccius), and a well defined seasonality, are alsoobserved in other studies of Mediterranean small-scale fisheries. We show that theseasonal rotation of fishing tactics is determined by the availability of different fishspecies rather than market price. Identifying the fishing tactics, which in theMediterranean are relatively limited in number, of small-scale fisheries providesinformation for developing monitoring and management strategies for these fisheries. Wealso assessed the economic performance of the small-scale fishery in Vilanova i la Geltrúand its conflicts with other uses of the coastal zone. We conclude that small-scalefisheries are an economically viable activity although seriously threatened by concurrentuses of the coastal zone (conflict with other extractive activities; competition for spacewith tourism and leisure activities; pollution). The integrated management of the uses ofthe coastal zone is necessary in order to sustain small-scale fisheries, which have becomeless important in economic terms, but which are an important social component of localcoastal communities and are a source of high quality seafood with a low ecological impact.

Echo sounder data were used to investigate the spatio-temporal variability of shoal behaviour in the Bay of Biscay. Data collected from annual surveys were processed using MOVIES-B software in order to mcasure this variability. The software was designed to measure morphological, energetic and space-time distribution descriptors from the acoustic signal received from fish shoals. Two surveys, DAAG 90 and DAAG 91, provided the appropriate characteristics for such an analysis. The survey's objective was to obtain relative abundance indices for the anchovy (Engraulis encrasicolus) biomass in the Bay of Biscay. The surveys were carried out in the same area (southern Bay of Biscay), at the same period (April) within one year interval (1990 and 1991), using the same equipment (vessel, acoustic system, fishing gear) in a multispecies environment. Frequency distributions for every descriptor were obtained and used to describe the acoustic detection of fish shoals. The analysis of frequency distributions of space-time descriptors (year, day-hour and bottom depth) allowed the construction of derived discrete variables, which defined new subsets of detections. The subsets were then described by the continuous variables. A principal components analysis was used to describe the multidimensional data structure and to describe behaviour patterns. The size and external outline unevenness are correlated groups of shoal descriptors, but are independent of the water column shoal position and the degree of internal shoal structure. An important feature is shoal size variability between years. Significant differences in shoal characteristics were found between bathymetric zones of the same region and the pattern was similar between years. This spatial wariability is related to the distribution of different species between bathymetric zones. Although it was not possible to explain size variability between years, this will be necessary to improve shoal characterization. More knowledge about oceanographic conditions, the productivity level and availability of food, predator pressure and accurate identification of shoal speeies is required, in order to study the spatial or temporal variability in size and behaviour of shoals.

The curve used until recently by the International Commission for the Conservation ofAtlantic Tunas (ICCAT) to represent the growth of western Atlantic bluefin tuna,Thunnus thynnus, was estimated using tagging information and modalsizes that corresponded primarily to very young fish (ages 1–3, primarily). The estimatedmaximum average size from this curve is very large (382 cm), which could be a result ofthe scarcity of large bluefin in the data used. Recently, scientists have developedtechniques for reading ages from bluefin ear bones (otoliths); the accuracy of the agereadings has been validated with bomb radiocarbon dating. These age readings are primarilyfor large bluefin (ages 5 and older), and indicate slower growth and older ages than waspreviously assumed. However, an analysis of these data resulted in growth curves thatpredicted very small mean sizes for the youngest age group, which could be a result of thelack of small fish in the data used. In this study, we combine the otolith-based agereadings with the size frequency distributions of small (ages 1–3) bluefin caught by purseseiners in the 1970s where the age groups are distinctly statistically as well as visibleto the eye. We analyzed the two datasets jointly using a maximum likelihood approach andassumed that variability in length-at-age increases with age. The resulting growth curvepredicts sizes at young and old ages that are very consistent with observed data such asthe maximum sizes observed in the catch and the modal sizes for very young bluefin. Theresulting curve is also very similar to the curve used by ICCAT for eastern Atlantic andMediterranean bluefin.

Anti-Bacillus megaterium activity was measured in unfractionated plasma withdrawn from three common US East Coast bivalve molluscs: an oyster Crassostrea virginica and the mussels Geukensia demissa and Mytilus edulis. The activities of the plasma samples from these bivalves were also measured against a C. virginica pathogen Perkinsus marinus. Strong anti-B. megaterium activity was measured in plasma from C. virginica and M. edulis, but was not detected in G. demissa. Bactericidal activity was found in hemocyte extracts from all bivalves in this study, suggesting a cellular origin of cytotoxic humoral factors. Peptides (< 10 kDa) were separated from the plasma samples by ultrafiltration; weak antibacterial peptide activity was quantified in C. virginica peptides, but not in peptides from the mussels. In the case of P. marinus, plasma from M. edulis or G. demissa was boldly cidal as compared to plasma from C. virginica. This difference in activity probably reflects the low pathogenicity of this oyster parasite for the mussel species tested. In summary, the bactericidal activity of plasma proteins from these bivalves showed considerable interspecies variation and did not necessarily correlate directly with antiprotistan activity. When present, antibacterial and antiprotistan activities seemed to be associated with plasma proteins rather than < 10-kDa plasma peptides, with the possible exception of C. virginica anti-B. megaterium activity and the occasionally expressed anti-P. marinus activity of M. edulis peptides. The precise identity of the plasma protein(s) responsible for the antimicrobial activities measured have yet to be determined, but it is likely that agents other than, or in addition to, lysozyme play significant roles in the process.