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Early life stages of fish are insufficiently studied in most regions around the globe, and consequently, there is an important gap in knowledge on the life cycle of most teleosts. In the Canary Islands (Eastern Central Atlantic), most studies on ichthyoplankton communities are based on traditional net tows in open waters that provide information about early larval stages of pelagic species in the area, while nearshore benthic fish remain highly understudied. In this study, light traps were employed for the first time to assess post-larval stages of neritic fish in this archipelago. A two-year survey was carried out to collect nearshore fish larvae every 6 months at 11 localities from El Hierro, Tenerife and Lanzarote. A total of 3940 fish larvae classified into 13 orders, 28 families and 44 species were collected. These results provide a wide description of the composition of the inshore ichthyoplankton off the Canary Islands, across islands and seasons. Main environmental factors (SST, sea floor orography, oceanographic phenomena ...) influencing the population dynamics of this community are discussed. Additionally, the ichthyoplankton assemblages were assessed from the intra-annual perspective, analyzing the species composition and abundances by months and seasons, and providing new insights into reproduction cycles of many common benthic fishes at shallow marine ecosystems of the islands. This study is important to further understand the life cycles of some of the most common fish species in the Canary Islands, unraveling main environmental factors that affect the success of their offspring that sustain populations. • Inshore ichthyoplankton community of the Canary Islands assessed by light traps. • Smaller coastal shelves off an island meant larger densities of fish post-larvae. • Changes in ichthyoplankton composition through months and seasons described. • New insights on life cycles of common fish species in the region. [ABSTRACT FROM AUTHOR]

Our previous work confirmed that the higher survival, growth, and commercial performance of a mussel stock collected from a specific lagoon have been maintained over the last 25 years at a microgeographic scale despite intensive transfers of its spat to other local mussel sites. The objective of this study was to identify potential selection mechanisms supporting the quality of this stock. We used a mesocosm approach to examine the effect of maximum seawater temperature measured in the field on the different ontogenic stages of Mytilus edulis to simulate similar patterns in the laboratory. We demonstrated that thermal selection did not affect the development of peri-metamorphic stages (< 1 mm) since no effects were observed on growth, survival, or prodissoconch II size under natural thermal variations. However, our experimental results clearly indicated the existence of a thermal selective pressure (24 °C for 85 h) on 4.5–7 mm juvenile mussels, with growth performance enhanced in surviving individuals. Mortality was 37% higher compared to the control group, suggesting the elimination of more sensitive and less performant mussels. Interestingly, surviving individuals showed improved shell and tissue growth rates, by 22 and 51%, respectively. Our results support the hypothesis that the thermal selection of highly performant stock is size-dependent. The selective pressure demonstrated in this study along with our previous work highlighting the physiological and genetic differences between local stocks constitute the key mechanisms leading to the observed stable production performance over decades at a microgeographic scale. • A selective pressure affecting late post-larval mussels (> 4.5 mm) was induced by thermal peak. • The thermal selection eliminated sensitive spat but led to enhanced growth of surviving individuals. • The development of early post-larvae (< 1 mm) appears not to be affected by this thermal selection. [ABSTRACT FROM AUTHOR]

This study evaluated different artificial substrates during pre-nursery of Pacific white shrimp in a biofloc system. Post-larvae (PL 5–80 PL L −1 ) were raised in 60 L tanks filled with 52 L of chlorinated seawater (35‰) and 6 L of the microalga Chaetoceros muelleri . Four treatments were performed, including control (no artificial substrate), Bidim ® (geotextile), mosquito net screen (2 mm mesh) and Needlona ® (polyester fiber). The total surface area of artificial substrate comprised 100% of the tank area (0.89 m 2 ). PLs were fed nine times a day using commercial feed. Molasses was added in all treatments four times a day at an average carbon:nitrogen ratio of 14.7:1. The experiment was carried out until the PLs reached PL20, and during this time, water quality, survival, weight gain and survival to salinity stress were all evaluated. Water quality parameters remained within the accepted levels for shrimp rearing, with the exception of total suspended solids (TSS) in mosquito net screen and control, which had the highest values (507 ± 5.50 mg L −1 and 565 ± 23.46 mg L −1 , respectively). Using Needlona ® as artificial substrate increased the survival rate (91 ± 11.6%) and reduced TSS (42%) when compared to the control. No significant differences were observed in final weight and survival to salinity stress. Among the different substrates, Needlona ® was the most suitable for application in Pacific white shrimp prenursery in the biofloc system, essentially because it could maintain levels of solids suspended in water without the use of clarifiers or water exchange, resulting in higher survival. [ABSTRACT FROM AUTHOR]

This study aimed to assess the movement patterns of post-larvae (PL) of whiteleg shrimp and black tiger shrimp, which were linked to the epidemic of acute hepatopancreatic necrosis disease (AHPND) in Thailand in 2013, using social network analysis. Hatcheries or nurseries were assigned as origin nodes, whereas cultivated ponds were designated as destination nodes. From 376 farms, data of 1300 ponds were collected from network data using a questionnaire. We found that 1477 nodes with 1315 ties appeared in this study. These were divided into a network of cases and controls that presented 538 nodes with 436 ties and 1013 nodes with 879 ties, respectively. The top four out-degree centrality values in the entire partial network, cases, and controls were used to analyze ego-alter similarity. The results showed that each PL provider played a different role in the association with the disease sender. A simulated network using exponential random graph models presented edges as a significant microstructure. In addition, our analysis indicated that the hatchery or nursery (PL provider) is an important node for AHPND occurrence. In conclusion, this study led us to understand the source of PL, which plays a key role in the surveillance, prevention, and control of AHPND. [ABSTRACT FROM AUTHOR]

In this study, we present the results of two experiments; in the first one we evaluated the effects of four larval dietary treatments on the survival and growth of the sea urchin Paracentrotus lividus , larvae and post-larvae. In the second experiment we have measured the effects of two different settlement substrates, combined with the presence of conspecifics, on metamorphosis, survival and growth of post-larvae. The microalgae dietary treatments consisted in: Dunaliella tertiolecta (Duna); 50% mixture of Isochrysis galbana and D. tertiolecta (ID); 50% mixture of Chaetoceros gracilis and D. tertiolecta (CD); 33% mixture of I. galbana , C. gracilis and D. tertiolecta (ICD). Although all dietary treatments resulted in a good survival at competence, significant difference in post-larval survival was observed between treatments, and indeed, only larvae fed Duna and CD survived to 180 days post settlement (DPS). In the second experiment, the settlement substrates consisted in a film of cultured Ulvella lens or a naturally developing biofilm of diatoms, and the employed rearing water was either natural seawater or seawater previously exposed to P. lividus adults. At 10 DPS, larger ( p < 0.05) post-larvae were observed in the natural biofilm treatment, whilst the presence of conspecifics significantly increased larval settlement in both substrates ( p < 0.01). These results indicate that it is important to consider the survival of post-larvae and juveniles to establish the efficiency of the dietary treatment on the hatchery production of P. lividus . Furthermore, it suggests that improved settlement protocols, such as the use of conspecifics, could contribute to increase hatchery outputs. Finally, it confirms the suitability of U. lens as settlement cue but also highlights that further research is required to establish its effectiveness for post-larvae first feeding. Statement of relevance Our work contributes to improving hatchery rearing methods of larvae and post-larvae of the sea urchin Paracentrotus lividus . [ABSTRACT FROM AUTHOR]

Populations of the Common European cockle ( Cerastoderma edule ) often have highly patchy distributions and variable recruitment success. One of the proposed reasons is that high densities of filter feeders and/or bioturbators are thought to reduce the success of larval settlement and post-settlement survival, but the direct causal processes driving these observations are not clearly identified and validated. Through combined field and laboratory experiments, we test the hypothesis that macrofauna cause decreases in post-larval density through feeding and movement activities. The effect of excluding the bioturbating lugworm Arenicola marina and filter-feeding adult cockles on post-larval cockle densities was estimated in separate field experiments at two locations from the time of initial larval settlement in May 2012 to late summer August 2012. Lugworm exclusion led to a significant increase in cockle post-larval densities whereas the opposite was true for adult cockles, where exclusion led to a reduction in C. edule post-larval density. Although clear effects were observed in the field, experiments conducted in the laboratory failed to detect changes in mortality or byssus drifting of post-larvae as a consequence of macrofaunal activity. This study demonstrates that the presence of macrofauna can have both positive and negative effects on post-settlement density of C. edule post-larvae. Thus the density, distribution and identity of macrofauna have significant effects on the density and spatial distribution of C. edule post-larvae during the post-settlement period. These observations have implications for conservation and fishery management of this species. [ABSTRACT FROM AUTHOR]

Understanding the spatial structure of populations at different scales can help reveal the processes controlling abundance and distribution. For species with a pelagic larval stage and highly mobile post-larval stage, such as the common cockle Cerastoderma edule , changes in spatial distribution from settlement through to juvenile stages are likely to occur at various spatial scales influencing the population dynamics observed. To record such changes a small-scale high-resolution field survey of C. edule post-larvae over an area of 60 × 80 m of tidal mudflat was conducted using a spatially-explicit staggered-nested design in the Dee estuary, UK. The survey was repeated three times from initial settlement in June 2011 to March 2012. Changes in spatial structure were described using Moran's I correlograms and prediction mapping, with analysis of correlations between cockle cohorts and sediment composition. At the first sampling event in June 2011, when initial settlement was occurring, post-larvae were highly aggregated in patches of 10–14 m in size and 16–20 m apart. By October 2011 the post-larvae had become more evenly dispersed with some small scale (< 4 m) random patchiness and a gradient in post-larval density. This spatial structure was maintained into March 2012 but with increased patchiness. At settlement post-larval density showed no correlation with adult abundance or sediment mud content, but by October 2011 and March 2012 there was a strong positive correlation with adult abundance. Such changes in spatial structure, abundance and adult association after settlement show the likely importance of small scale (metres to tens of metres) processes on post-larval survival from predation and adult interactions, thereby potentially shaping adult distributions. Small scale patchiness in post-larvae can be created at settlement; however the distribution and association with adults change over time. [ABSTRACT FROM AUTHOR]

Giant freshwater prawn ( Macrobrachium rosenbergii , de Man, 1879) is an important commercial species due to its importance as food supply as well as a valuable export product. Since invertebrates lack a true adaptive immune response, stimulating M. rosenbergii for protection against white tail disease (WTD) with r-MCP capsid protein is a possible approach. The effectiveness of intramuscular injection of adult freshwater prawn with r-MCP protein and immersion of post-larvae (PL) of M. rosenbergii in r-MCP protein were investigated for their ability to protect against white tail disease. In experiment 1, the r-MCP protein injected adult prawn showed good immune response compared to PBS injected adult M. rosenbergii (mean body weight: 14.3 g). Samples were collected at different day intervals (24, 72, 120 and 168 h) to analyze the hematological and immunological parameters and to study the immune-related and HSP gene expressions with β actin as internal control in hemocytes, gill tissue and hepatopancreas by RT-PCR and quantification of immune and HSP gene expression by quantitative real-time PCR. In experiment II, the PL (10–12) of M. rosenbergii were exposed to r-MCP protein by immersion for 24 h and challenged with Mr NV and XSV inoculum at a volume equal to 0.1% of the total rearing medium. The samples were collected at different day intervals, i.e. 1st day, 2nd day and 5th day from treated group and 1st day, 5th day and moribund samples from Mr NV and XSV infected PL group to analyze the expression of immune-related gene of M. rosenbergii by RT-PCR. Quantitative real-time PCR was employed to determine the cycle threshold ( C T ) value of immune gene expression with β actin as host gene. The obtained percentage survival of post-larvae treated with purified r-MCP protein and challenged with Mr NV and XSV was 76.03% on 15th day p.i., 99.78% survival was recorded in normal group on 15th day p.i. and 0% survival was recorded in Mr NV and XSV infected group on 10th day p.i. This suggests that the prawn immune system is able to specifically recognize and react with protein. This study shows that stimulation of the immune system of prawn with r-MCP helps to control WTD in giant freshwater prawn, M. rosenbergii . [ABSTRACT FROM AUTHOR]

Abstract: Population connectivity scales are important tools to achieve a mechanistic understanding of the factors regulating the abundance and distribution of marine populations and therefore support conservation actions to manage fisheries and stocks. We used 10 microsatellites markers on mullets' samples across the Spanish coast to determine the spatial scale of gene flow as well as the origin of post-larvae caught inside two MPAs. Population structure varied from complete homogeneity for Mullus barbatus, to high spatial variability in Mullus surmuletus samples. Differential habitat utilization by species, geomorphological features and oceanographic patterns are discussed as potential causes of patterns observed. Although we were unable to verify the origin of most post-larvae caught inside MPAs we suggest that they may act as genetic reservoirs due to high heterozigosity levels found in adult specimens inside (M. surmuletus) and nearby (both) them. Our results indicate that early life history traits (i.e. larvae) may not be the only determinant on species dispersal capability, suggesting that other mechanisms such as fine scale adult or juvenile movement may have been underestimated as promoting population connectivity. [Copyright &y& Elsevier]

Abstract: Four diatoms species Amphora sp., Navicula incerta, Nitzschia sp. and Proschkinia sp., were tested as food for Haliotis tuberculata coccinea post-larvae. Larvae were settled on Ulvella lens and Ulva rigida germlings at a density of 0.5larvaecm2 of substrate. Growth and survival, in each dietary treatment, were monitored during ten weeks. Experimental nursery tanks were weekly inoculated with 2L of the different diatom inoculums (105–106 cellsmL−1). Proximate biochemical compositions were significantly different for the four diatom species. Amphora sp. presented a significantly higher lipid and protein contents with 7.11±0.29% DW and 18.50±0.97% DW respectively, while Proschkinia sp. presented the lowest protein content and the highest ash content. The fatty acid profiles of the diatoms were variable but remained typical of the diatom family. Larvae contained significantly more lipids (25.30±0.93% DW) than juveniles. The different fatty acid compositions found for the various diatom species were dissimilar to the ones of larvae, juveniles and substrates; (Courtois de Viçose et al., in press-a) the fatty acid compositions of these last two not being different among treatments. 16:4n−3, 20:4n−6 (arachidonic acid, ARA) and 22:5n−3 (docosapentaenoic acid, DPA) were the most abundant fatty acids in juveniles while 20:5n−3 (ecosapentaenoic acid, EPA) was the dominant polyunsaturated fatty acid (PUFA), present at a comparable level in all diatoms. This suggests that the post-larvae and juveniles are capable to absorb a selection of fatty acids from the food source or that they are able to synthesise them from precursor dietary fatty acids. Growth rates obtained in the present study are presenting different phases and diatom diets made little difference to growth rate of post-larvae until reaching around 0.8–1mmSL, after which divergence in growth rate among diets became significant. Post-larvae fed the diatom with the highest protein and lipid contents (Amphora sp.) showed the best daily growth rate (DGR) of 50±3μm over the feeding trial, highlighting the joint influence of diatoms’ protein and lipid content on growth. Around 2mmSL, juveniles exhibited increased growth rates, in all treatments, reaching 94μmday−1, indicating a possible shift in nutrition towards green macroalgae germlings and suggesting that U. lens and U. rigida are used as a complement to the diatom diet at this stage. 18:2n−6 and 18:3n−3 found in high amount in all juveniles as well as in all substrates could be an indication of that nutritional shift and could be involved in growth enhancement. [Copyright &y& Elsevier]

Abstract: Critical thermal minima (CTMin) and maxima (CTMax) values were determined for the Pacific white shrimp Litopenaeus vannamei post-larvae and juveniles at four different acclimation temperatures (15, 20, 25, and 30°C). The CTMin of shrimp at these acclimation temperatures were 7.82, 8.95, 9.80, and 10.96°C for post-larvae and 7.50, 8.20, 10.20, and 10.80°C for juveniles, respectively, at 1°Ch−1 cooling rate. The CTMax values were 35.65, 38.13, 39.91, and 42.00°C for post-larvae and 35.94, 38.65, 40.30, and 42.20°C for juveniles at the respective acclimation temperatures. Both acclimation temperature and size of the shrimp affected CTMin values of L. vannamei (P<0.01). Overall, juveniles displayed significantly lower CTMin values than the post-larvae (P<0.0001). However, the CTMax response by post-larvae and juveniles were not significantly different from each other and no interaction was determined between the acclimation temperature and development stage (P>0.01). The area of the thermal tolerance polygon over four acclimation temperatures (15, 20, 25, and 30°C) for the post-larvae of L. vannamei was calculated to be 434.94°C2. The acclimation response ratio (ARR) values were high ranging from 0.35 to 0.44 for both post-larvae and juveniles. L. vannamei appears to be more sensitive to low temperatures than other penaeid species and its cold tolerance zone ranged from 7.5 to 11°C. In successful aquaculture temperature must never fall below 12°C to prevent mortalities. Upper thermal tolerance is less of a problem as in most subtropical regions maximum water temperature rarely exceeds 34°C, but care should be given if shallow ponds with low water renewal rate are being used. [ABSTRACT FROM AUTHOR]

Abstract: To elucidate the effects of delayed metamorphosis and delayed post-settlement feeding on larval competence and post-larval survival and growth in the small abalone Haliotis diversicolor, we examined three sets of experiments. First, a pebble coated with crustose coralline algae (CCA) was used to induce competent H. diversicolor larvae to metamorphose at 2, 5, 8, 12, or 17days (Group A) or 2, 6, 10, or 12days (Group B) after fertilization. To observe spontaneous attachment and metamorphosis, some larvae from Group B were maintained without the addition of a CCA-coated pebble. Rapid metamorphosis was observed in older larvae of both CCA-induced groups; 2days after the addition of the CCA-coated pebble, 50–75% of the 2-day-old larvae and more than 85% of the 5–12-day-old larvae had metamorphosed. The percentage of spontaneously metamorphosed individuals increased 14days after fertilization, reaching 50.6±16.7% (mean±S.E.) at 18days. Second, metamorphosed post-larvae that had experienced larval periods of 5, 8, 11, or 15days (Group A) or 4, 7, or 10days (Group B) were reared at 26°C with or without the benthic diatom Nitzchia ovalis as the sole food source. The survival and growth rates of the fed post-larvae in both groups decreased with the length of the larval swimming period; of the post-larvae from larvae of more than 7–11days old, fewer than 70% still survived 16days after metamorphosis. Mean growth rates during the 6days after metamorphosis were lowest for the post-larvae from the larvae with the longest period of swimming. Third, newly settled post-larvae from 2-day-old larvae were reared at 26°C with delays of 0, 3, 6, 9, or 12days before first feeding (N. ovalis). Feeding delays of longer than 6days dramatically depressed post-larval survival rates; approximately 1week after the onset of feeding, more than 65% and fewer than 20% of the larvae subjected to feeding delays of 0–3days or 6–12days, respectively, still survived. These results indicate that H. diversicolor is more susceptible to the detrimental effects of delayed metamorphosis and delayed post-settlement feeding than are the larger abalone species Haliotis discus hannai and Haliotis iris. [Copyright &y& Elsevier]

Abstract: The nutritional value of four microalgal species: Chaetoceros muelleri, Pavlova lutheri, Tahitian strain of Isochrysis sp. (TISO), and Thalassiosira pseudonana in single- and bi-species diets was evaluated for larvae and post-larvae of the basket cockle, Clinocardium nuttallii. Larval shell growth and metamorphic rate were found to be the greatest with both single- and mixed-species diets comprising TISO. For the post-larvae, however, optimal shell growth was observed in both single- and mixed-species diets containing Chaetoceros muelleri. In another feeding experiment, the microalga Tetraselmis suecica was tested singly and in combination with TISO. Results showed that the food value of Tetraselmis suecica alone was poor for both larvae and post-larvae. In contrast, the mixed-species diet of Tetraselmis suecica and TISO resulted in significantly improved larval and post-larval growth, similar to the respective best (control) diets as identified in the first experiment. It is concluded that, for the hatchery production of Clinocardium nuttallii seed, a single-species diet of TISO is the best for the larvae and a single-species diet of Chaetoceros muelleri is the best for the post-larvae. A nutritional transition period during which both the microalgal species may be required, is also suggested for the hatchery production of basket cockle seed. [Copyright &y& Elsevier]

Abstract: Protein synthesis is a major determinant of growth and yet little is known about the environmental factors that influence protein synthesis rates in farmed freshwater prawns. To this end, post-larvae and juveniles of Macrobrachium rosenbergii were exposed to various salinities (0, 14, 30‰) to determine whole-animal rates of fractional protein synthesis (k s) and oxygen uptake. In the post-larvae that migrate upstream from brackish to freshwater areas, whole-animal k s was unaffected by salinity, but rates of oxygen uptake were significantly lower at 14‰. In the freshwater juveniles, a different response was observed, as mean k s was significantly higher at 14‰ compared with 0‰, but rates of oxygen uptake remained unchanged. Such differences are thought to be related to the energetic costs of osmoregulation and to the ability to maintain osmotic gradients in freshwater. In an additional experiment, acclimation temperature (20, 26, 30 °C) had a direct effect on k s in juveniles held at 0‰. In all cases, changes in k s resulted from alterations in RNA activity at constant RNA capacity. In juveniles at least, whole-animal rates of protein synthesis were highest at 14‰ and 30 °C which corresponds to the optimal salinity and temperature recommended for the growth and culture of M. rosenbergii. [Copyright &y& Elsevier]

Abstract: In a commercial scallop hatchery spat production depends on a culture system which ensures high survival and good growth. Reuse of water with algae may increase the food exploitation and hence reduce the costs. Post-larvae of great scallop (Pecten maximus) were studied in a commercial hatchery using a partial open and continuous feeding tank system. Three different water recirculation rates (67, 83 and 92%) were tried out in two experiments with post-larvae originating from three spawning groups of ages between 43 and 57 days post-spawn, 316–886μm shell-height and 1.1–9.6μg ash-free dry weight. The post-larvae were held in sieves in tanks of 2500l where a downwelling flow was maintained by airlifts. New water with a mix of monocultured algae was continuously added to the tanks at algal concentrations of 10 and 15cellsμl−1 in experiment 1 (groups 1 and 2) and 2 (group 3), respectively. The algal supply to each sieve was reduced along with increased recirculation rate, but was kept between 6 and 13cellsμl−1. Generally no significant differences in survival, growth or chemical content were found between the three recirculation rates, while few differences were found between and within groups. Large variation in survival was found between and within groups (1–81%). Highest survival was found in experiment 1, and where post-larvae from two settlements were used, the first settlement survived better than the second. The daily growth ranged from 15 to 62μm shell-height and from 0.3 to 2.6μg ash-free dry weight. The scallop post-larvae could well be reared at all three recirculation rates studied as an increase from 67 to 92% did not seem to affect the post-larval performance seriously. The algal supply, however, had to be compensated by an increasing number of cells (>10cellsμl−1) when increasing the recirculation rate. [Copyright &y& Elsevier]

Abstract: The feeding of the late larval stages of the spiny lobster, Panulirus cygnus, and the energy reserves used by the non-feeding post-larvae for crossing the continental shelf of Western Australia were examined through their lipid composition. Lipid was a significant component of the biomass of all larval and post-larval samples (range 63–213 mg g−1 of dry biomass). The fatty acid profiles of late stage larvae (8–9) suggest that they were feeding on salps and small crustaceans, such as euphausids, from oligotrophic pelagic communities where herbivorous and microbial grazing is an important basis to the food web. There was a marked decrease in lipid content of post-larvae progressively across the continental shelf, and this corresponded closely with decreasing dry mass, suggesting that post-larvae were using lipid as an energy source during cross-shelf movement at a rate of 1.6 J km−1. This is considerably lower than for other spiny lobster species, suggesting that the post-larvae of the western rock lobster may use physical processes as well as active swimming for onshore transport. This may help to explain the large inter-annual variability in the post-larval settlement of this species, which is closely related to differences in weather patterns capable of greatly varying onshore advection processes. [Copyright &y& Elsevier]

A feeding trial was conducted to study the effect of iso-energetic diets containing 250 (D1), 300 (D2), 350 (D3) and 400 g (D4) crude protein (CP) kg−1 dry matter (DM), in hybrid post-larvae of Clarias batrachus ♀ × Clarias gariepinus ♂. Triplicate groups of post-larvae with mean initial body weight 67±6 mg were reared in cement tanks (4 m×1 m), in outdoor rearing system and fed diets at 10% of body weight for 30 days. Performance was judged on the basis of growth (specific growth rate, SGR), percent survival, feed conversion ratio (FCR) and protein efficiency ratio (PER), which were influenced both linearly and quadratically. An increase in body weight gain, SGR, PER and decreased FCR was observed with increasing dietary protein. The percent survival was increased linearly (P<0.01) as well as quadratically (P<0.05) among fish fed increased levels of protein. Both amylolytic and proteolytic enzymes in the intestine of hybrid Clarias catfish were studied. The α-amylase activity decreased linearly (P<0.05) with increased dietary protein level and protease activity increased.The fish accumulated increasing (linear component, P<0.05) protein as well as ash and decreasing lipid in the whole body with increasing dietary protein. The broken-line regression analysis indicated that for maximal growth, hybrid Clarias catfish post-larvae require 365 g dietary crude protein kg−1 diet. [Copyright &y& Elsevier]

The development from the non-feeding post-larva (puerulus) to the first instar juvenile of spiny lobsters is highly energetically demanding. These demands may greatly compromise the energy reserves of the lobsters following settlement, leading to reduced growth and survival in the wild, and also in aquaculture. Therefore, the lipid class and fatty acid composition of wild caught pueruli and first instar juveniles of the spiny lobster Jasus verreauxi (H. Milne Edwards, 1851) were analysed by thin layer chromatography-flame ionisation detection and capillary gas chromatography. Pueruli contained substantially more lipid than first instar juveniles (mean difference =3.5 mg, or 41.9%) and most of this difference was due to the presence of greater amounts of polar lipid (mean difference =3.9 mg or 49.2%) in pueruli. First instar juveniles contained significantly more triacylglycerol (mean =0.2 mg), consistent with the polar lipid being converted to a more readily metabolised lipid class in the hepatopancreas. These results indicate that polar lipid is the major energy store during the non-feeding puerulus stage of spiny lobsters from the genus Jasus. Overall, the essential, polyunsaturated linoleic, docosahexaenoic and eicosapentaenoic acids did not show a significant decrease between the two developmental stages, despite the absence of feeding. However, significant reductions in the abundance of both saturated and monounsaturated fatty acids between the two stages were identified (decrease of 811 and 783 μg per individual, respectively). This suggested that selective depletion of non-essential fatty acids may be occurring, with resultant sparing of the essential fatty acids. Supplying diets rich in these depleted fatty acids, and in particular the essential fatty acids, preferably in polar lipid, is likely to result in increased survival and growth of J. verreauxi and other spiny lobsters from first instar juveniles in aquaculture. [Copyright &y& Elsevier]

Tripneustes ventricosus is a commercially important species of sea urchin native of the tropical Atlantic Ocean. With the purpose of providing a scientific basis for the development of its production by aquaculture, several experiments were performed under hatchery conditions, including spawning induction, larval culture, settlement and juvenile culture. The efficiency of different spawning stimuli was assessed, including the use of UV-irradiated seawater; thermal and electric shocks, and injections of potassium chloride (KCl) and acetylcholine (ACh). Growth and survival of larvae maintained at different culture conditions were compared, including culture densities (2, 6 and 12 zygotes mL−1; 0.5, 1 and 2 larvae mL−1), culture systems (9 L aquaria, 75 L and 500 L tanks), water renewal rates (total and partial), feed amount (15 and 30 cells μL−1 d−1), feeding regime (constant or increasing) and type of diet (Isochrysis galbana, and a mixture of I. galbana and Chaetoceros calcitrans). Different stimuli to induce the larval settlement were tested, including low temperature, KCl, l -glutamine and γ-aminobutyric acid (GABA), as well as different substrates (artificial and benthonic microalgae biofilms). Finally, the growth and survival of juveniles were assessed under indoor conditions. The highest percentage of spawning individuals and the shorter response times were obtained using ACh. The average fecundity was 1.5 × 106 oocytes female−1. This variable exhibited a positive correlation with the female body size. One of the most relevant results of the present study was the completion of the embryo and larval developmental stages of T. ventricosus. Higher levels of larval either survival or growth were found in the tanks with the highest volume (500 L), maintaining conditions of low culture densities and complete water renewal and a constant supply of microalgae during all the larval development stage (15 cells of I. galbana and C. calcitrans μL−1 day−1). The larval settlement was obtained using low temperatures in all the tested substrates, except the substrate with artificial biofilm containing Sargassum and Thalassia. After 9 months of culture in laboratory conditions, juveniles of 44-mm length were obtained, using a regime of complete water renewal, and feeding the larvae with artificial biofilm, benthic microalgae and macroalgae. Although the present study made possible to identify appropriate culture conditions for obtaining hatchery-reared juveniles of white sea urchin, the low survival rates observed during the larval culture and the settlement stage must be improved with further research on the feeding requirements and the optimal water quality conditions for this species. • This is the first report of fecundity, early larval development and settlement of T. ventricosus. • Acetylcholine injection was the most effective method for T. ventricosus spawning induction. • The basic culture conditions and feeding regime required for obtaining competent larvae of T. ventricosus were determined. • The larval settlement of T. ventricosus was obtained reducing the water temperature in almost all the tested substrates. • -The high growth and survival rates of T. ventricosus juveniles are promising results for its aquaculture use. [ABSTRACT FROM AUTHOR]