Roger Villanueva

The biodiversity of the Mediterranean Sea: estimates, patterns, and threats.

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well. This abstract has been translated to other languages (File S1).

Lipid and fatty acid composition of early stages of cephalopods: an approach to their lipid requirements.

We report here the main lipid classes and the fatty acid composition from the total lipids of hatchlings of three cephalopod species: Sepia officinalis, Loligo vulgaris and Octopus vulgaris, as well as the lipid composition of two selected crustaceans that have been used previously with success as food resource for rearing cephalopod hatchlings: zoeae of Pagurus prideaux and the mysidacean Acanthomysis longicornis. Additionally, we report the lipid class and fatty acid composition of two cultures of O. vulgaris paralarvae reared with enriched Artemia juveniles, and with enriched Artemia juveniles plus a prepared pelleted diet. From their lipid composition and that of their natural food, it can be deduced that cephalopod paralarvae and juveniles must require a food rich in polyunsaturated fatty acids (PUFA), phospholipids and cholesterol and with a moderate content in neutral lipids. There was a clear influence of the lipid composition of the food on the lipids of cultured octopus paralarvae both at the level of lipid class and fatty acid composition. The cultured octopus paralarvae showed a lower content of PUFA as compared with the newly hatched individuals. Co-feeding techniques based on the use of polar lipid and PUFA enriched Artemia together with palatable pellets seemed to be a possible way to improve paralarval and juvenile cephalopod culture beyond the experimental scale.

The fatty acid composition of Octopus vulgaris paralarvae reared with live and inert food: deviation from their natural fatty acid profile

Abstract The fatty acids of the mature ovary, late eggs and wild juveniles of Octopus vulgaris were analysed to establish, in accordance with the published data on the fatty acid composition of hatchlings, a theoretical framework of the ideal fatty acid profile, i.e. the “natural” fatty acid profile, during the early life of the species. The time course variation of the fatty acid composition of paralarvae reared in cultures fed enriched Artemia nauplii on their own, or supplemented with encapsulated microdiets, was also analysed and compared. The fatty acid composition of the cultured planktonic paralarvae was chemometrically related to that of the wild benthic juveniles by means of a multivariate discriminant analysis. Irrespective of the dietary treatment, the artificial feeding produced distinct lipid and fatty acid profiles as compared to the “natural” one. The influence of the fatty acid profile of Artemia seems clearly reflected in the cultured O. vulgaris paralarvae. The effect of the fatty acid composition of food was evident in the paralarvae after 10 days of feeding and remained essentially unchanged during the experimental period up to 30 days. The total lipid of the cultured animals increased notably, as did the levels of monounsaturated fatty acids, to the detriment of polyunsaturated fatty acids (PUFA) and, particularly, docosahexaenoic acid (DHA). Poor growth and high mortality seemed to result from a nutritional imbalance in the fatty acid profile (i.e. DHA/eicosapentaenoic acid (EPA) ratio) produced by the artificial feeding, suggesting also that the microdiet was inefficiently digested and/or assimilated. Wild juveniles tend to lose lipids as they increase in weight. Possible causes are discussed.

Ethical and welfare considerations when using cephalopods as experimental animals

When using cephalopods as experimental animals, a number of factors, including morality, quality of information derived from experiments, and public perception, drives the motivation to consider welfare issues. Refinement of methods and techniques is a major step in ensuring protection of cephalopod welfare in both laboratory and field studies. To this end, existing literature that provides details of methods used in the collection, handling, maintenance, and culture of a range of cephalopods is a useful starting point when refining and justifying decisions about animal welfare. This review collates recent literature in which authors have used cephalopods as experimental animals, revealing the extent of use and diversity of cephalopod species and techniques. It also highlights several major issues when considering cephalopod welfare; how little is known about disease in cephalopods and its relationship to senescence and also how to define objective endpoints when animals are stressed or dying as a result of the experiment.

Growth and proteolytic activity of Octopus vulgaris paralarvae with different food rations during first feeding, using Artemia nauplii and compound diets

Experiments were conducted to investigate growth and proteolytic activity of the common octopus Octopus vulgaris, reared with different diets and ration levels during first feeding. Four ration levels were tested, 0.2, 2, 4 and 10 Artemia nauplii ml 1 day 1 and co-feeding techniques were tested using 10 Artemia nauplii ml 1 day 1 plus three different compound millicapsules. Total proteolytic activity, trypsin and chymotrypsin levels were recorded from eggs, hatchlings and during the first month of paralarval rearing. Five days after hatching, paralarval weight and proteolytic activity was dependent on food ration. The low-food treatment did not lead to an increase in hatchling weight, in contrast with the positive increase of the other treatments. After 20 days, best survival was observed in treatments fed 2 and 4 nauplii ml 1 day 1 . High nauplii rations of 10 nauplii ml 1 day 1 plus millicapsule diet treatments produced higher growth and higher proteolytic, trypsin and chymotrypsin levels, but poor survival. Total proteolytic activity was correlated with paralarval weight, whereas trypsin and chymotrypsin were maintained at hatchling levels only for the high food and co-feeding treatments, and decreased in the others. The trypsin activity in the high-food treatment showed a sharp increase after 15 days and 880 mg of the mean dry weight (2.5 times hatchling weight). Millicapsules were ingested by the paralarvae after 5 days but did not lead to a significant increase in weight. Enriched Artemia nauplii seem to be useful only as an initial diet until a doubling in hatchling weight is achieved. This period can extend from 11 to 14 days at 20 � C, after which a larger prey and/or suitable microdiet is required. D 2002 Elsevier Science B.V. All rights reserved.

Decapod crab zoeae as food for rearing cephalopod paralarvae.

Abstract A simple method of providing a regular supply of live food for the experimental culture of paralarval cephalopods is described. The primary food source utilized was hatched zoeae of large laboratory populations of the hermit crab, Pagurus prideaux . Zoeal size, swimming behaviour, and distribution in the water column make these zoeae a suitable live prey for rearing early post-hatching planktonic stages of cephalopods and probably other marine zooplanktivores. Ovigerous P. prideaux females were collected from the sea throughout the year at depths between 10 and 90 m in the NW Mediterranean and maintained at densities of up to 500 specimens · m −2 . One month after spawning in aquaria, 38% of the females of P. prideaux started to incubate a second clutch of eggs. Other decapod crustacean species, such as Liocarcinus depurator and Dardanus arrosor , were maintained to use their zoeae as a food source for cephalopod paralarvae. P. prideaux zoeae were used as the sole or main food resource for rearing Loligo vulgaris and Octopus vulgaris , during the first 2 months of life. First feeding and initial growth in L. vulgaris and O. vulgaris paralarvae can be successfully stimulated using decapod zoeae with a total length equivalent to 50–100% of the cephalopods mantle length.

Swimming behaviour and food searching in planktonic Octopus vulgaris Cuvier from hatching to settlement

Abstract The planktonic life in Mediterranean Octopus vulgaris lasts about 2 months but we know virtually nothing of this phase of its life history, which represents around 10–15% of the estimated life span. Swimming behaviour from hatching to settlement was studied by video-recording techniques, using five groups aged 1, 15, 30, 42 and 60 days, by when they have become benthic. During the planktonic stage, the backwards, squid-like jet swimming was the predominant type of displacement. Strong morphometric changes, basically in arm growth, influence their jetting capacities and probably the settlement process. Feeding behaviour was analyzed using two species of decapod zoeae as prey, Liocarcinus depurator (L.) and Pagurus prideaux Leach; it is that of a visual predator. The forward displacement typically forms part of this predatory behaviour. During the planktonic phase, the presence of prey increases the turning rate and reduces the swimming speed of Octopus vulgaris individuals. Both responses may improve the exploitation of patchy food environments.

Continuous spawning in the cirrate octopods Opisthoteuthis agassizii and O. vossi: features of sexual maturation defining a reproductive strategy in cephalopods

The reproductive strategy of the cirrate octopods Opisthoteuthis agassizii and O. vossi (collected off Namibia from 1988 to 1990) was analyzed. Ovarian oocyte size frequency analysis for both species revealed continuous egg production over the entire adult life span. Mature eggs were stored in the single oviducal gland and distal oviduct, but oviducal gland fullness was not related to body size (p>0.2). All O. agassizii male specimens from 95 to 5400 g total weight were sexually mature, as were all females from 190 to 1650 g, indicating that considerable growth takes place after the onset of sexual maturity. “Continuous spawning” is defined as a single, extended and continuous period of egg maturation and spawning. This model of reproductive strategy is previously unreported in cephalopods. All O. vossi male specimens from 750 to 3050 g total weight, and females from 800 to 1300 g, were sexually mature. Mature males and females of both species were collected in all seasons of the year. The adaptation of cirrate octopods to non-scasonal deep-sea environments is considered. The sexual maturity characteristics of males were analyzed, and examination of the spermatophore revealed opercular structures previously unreported in cephalopods. For females, the micropyle of the eggs are described and the mineral analysis of the egg shell disclosed that sulphur was the major element present.

Cephalopod Culture: Current Status of Main Biological Models and Research Priorities

A recent revival in using cephalopods as experimental animals has rekindled interest in their biology and life cycles, information with direct applications also in the rapidly growing ornamental aquarium species trade and in commercial aquaculture production for human consumption. Cephalopods have high rates of growth and food conversion, which for aquaculture translates into short culture cycles, high ratios of production to biomass and high cost-effectiveness. However, at present, only small-scale culture is possible and only for a few species: the cuttlefish Sepia officinalis, the loliginid squid Sepioteuthis lessoniana and the octopuses Octopus maya and O. vulgaris. These four species are the focus of this chapter, the aims of which are as follows: (1) to provide an overview of the culture requirements of cephalopods, (2) to highlight the physical and nutritional requirements at each phase of the life cycle regarded as essential for successful full-scale culture and (3) to identify current limitations and the topics on which further research is required. Knowledge of cephalopod culture methods is advanced, but commercialization is still constrained by the highly selective feeding habits of cephalopods and their requirement for large quantities of high-quality (preferably live) feed, particularly in the early stages of development. Future research should focus on problems related to the consistent production of viable numbers of juveniles, the resolution of which requires a better understanding of nutrition at all phases of the life cycle and better broodstock management, particularly regarding developments in genetic selection, control of reproduction and quality of eggs and offspring.

Interannual growth differences in the oceanic squid Todarodes angolensis Adam in the northern Benguela upwelling system, based on statolith growth increment analysis

Analysis of growth by year of hatching was estimated from the statolith growth increments of the oceanic squid Todarodes angolensis in three consecutive years. Samples were taken between November 1987 and February 1990 in the northern Benguela upwelling system. Growth increments suggested that hatching took place throughout the year and that the life cycle was ≈ 1 yr. From the onset of sexual maturity in the final third of the life cycle, growth rates were subject to considerable individual variation. Growth rate was significant highest in the 1987 year class, presumably because of exceptionally cool environmental conditions in the Benguela region. The response of T. angolensis to interannual environmental variability in the northern Benguela system is discussed. The results from this study suggest that it will be important to consider variability in growth rate in relation to environmental conditions, in future studies of squid age and growth.