Wild Postlarvae Research Articles

Rearing condition influences gene expression in postlarval American lobster (Homarus americanus).

The American lobster (Homarus americanus) is an economically important species in the western Atlantic and its climate-driven range shift northward along the east coast of the United States is well documented. The thermal tolerance of lab-reared postlarvae of this species has been extensively investigated to better understand settlement and recruitment dynamics. However, there have been few studies focused on wild-caught postlarvae, and even fewer that have analyzed lab-rearing conditions in context of diet. In this study, we investigated gene transcriptional changes in postlarvae caught in the wild, as well as postlarvae reared in the laboratory on a brine shrimp diet or a wild-sourced zooplankton diet. We found between wild-caught and brine shrimp-reared larvae 3,682 differentially expressed genes, and between wild and zooplankton-reared postlarvae 3,939 differentially expressed genes. Between the two lab-reared groups fed different diets 2,603 genes were differentially expressed. We also exposed individuals in all rearing groups to chronic temperature treatments of 8°C and 26°C and found that both temperature extremes elicit 68-95% fewer transcriptional changes in wild postlarvae compared to either lab-reared group. In wild postlarvae, we identified differential expression of transcripts within the FoxO signaling pathway, a signaling pathway with a central role in cellular physiology, as potential molecular markers for cold tolerance in the American lobster. These findings contextualize the current literature on lab-reared postlarvae as containing conservative estimates for in situ organisms and can be used to inform population distribution modeling efforts. They also provide evidence for the need to adjust lab-rearing techniques or source wild larval crustaceans to augment studies of larval biology.

Comparative quality assessment of wild and hatchery-produced black tiger shrimp (Penaeus monodon) post-larvae in pre-stocking nursing condition

Farmers of Bangladesh like to stock wild post-larvae (PL) of Black tiger shrimp (Penaeus monodon). However, wild PL collection is detrimental to aquatic biodiversity, and the supply of hatchery PL is sufficient. The study was conducted in Cox's Bazar, Bangladesh, to compare the quality aspects of wild and hatchery PL in terms of size variation, survival, tolerance, and morphology.

IMPACTOS AMBIENTAIS DOS CULTIVOS DE CAMARÕES MARINHOS NO NORDESTE DO BRASIL

Com a estabilização da pesca em escala mundial, a aqüicultura surge como a mais importante alternativa. Entre os recursos marinhos cultivados, os camarões peneídeos representam o grupo mais promissor no Brasil. Após seu início na década de 70 do século passado, a carcinicultura marinha brasileira, passou por uma série de crises, até atingir o patamar do sétimo maior produtor mundial e líder da América Latina, em 2002, com uma produção de 60.128 t. A Região Nordeste brasileira é responsável por 96,5% dessa produção, quando se considera toda a cadeia produtiva. O tema carcinicultura tem sucitado controvertidos debates entre ambientalistas e a classe produtora. Como principiais danos, a carcinicultura causaria a destruição de manguezais, salinização de aqüíferos, poluição das áreas adjacentes pelos efluentes das fazendas, perda da biodiversidade durante a coleta de pós-larvas e escape de espécies exóticas para o ambiente natural. Todos estes pontos podem ser mitigados pela as boas práticas de cultivo, e alguns deles já não atingem os carcinicultores brasileiros, tais como a construção de viveiros em áreas de mangue e coleta de pós-larvas silvestres. É indiscutível que continuidade deste importante agronegócio depende da proteção do meio ambiente, ao qual está intimamente ligado.

The impact of climate change on prawn postlarvae fishing in coastal Bangladesh: Socioeconomic and ecological perspectives

In Bangladesh, prawn (Macrobrachium rosenbergii) farming remains dependent on the capture of wild postlarvae as hatchery production is still inadequate. However, prawn postlarvae fishing has been accompanied by concerns over recent climate change. Different climatic variables including cyclone, salinity, sea level rise, water temperature, flood, rainfall, and drought have had adverse effects on coastal ecosystem, thus determining a decline in the availability of prawn postlarvae and thereby catch. The households of postlarvae fishers also face a variety of socioeconomic constraints due to climate change. Considering extreme vulnerability to the effects of climate change, an integrated approach needs to be introduced to cope with the challenges.

Prawn postlarvae fishing in coastal Bangladesh: Challenges for sustainable livelihoods

Fishing for prawn (Macrobrachium rosenbergii) postlarvae is a major contributor to the livelihoods of the coastal poor in Bangladesh, including women. A study of coastal livelihoods along the lower Pasur River in southwest Bangladesh indicates that on average 40% of total annual income comes from postlarvae fishing during the few months involved. However, indiscriminate fishing of wild postlarvae, with high levels of by-catch, has an impact on biodiversity in coastal ecosystems. This has provoked imposition of restrictions on postlarvae collection. The ban has, however, not been firmly enforced because of the lack of alternative livelihoods for coastal poor. A conceptual framework, drawn from an approach to poverty reduction known as the sustainable livelihoods approach, is applied to understanding the role of prawn postlarvae fishing. Evidence from this study suggests that postlarvae fishers faced a number of livelihood constraints, including poor livelihood assets. This paper concludes that wider livelihood options need to be found for postlarvae fishers to support their livelihoods.

Comparing skeletal development of wild and hatchery-reared Senegalese sole (Solea senegalensis, Kaup 1858): evaluation in larval and postlarval stages

The Senegalese sole is a marine pleuronectiform that naturally occurs in Southern Europe and Mediterranean region where it is being produced in aquaculture, in particular in Portugal and Spain. The aim of this study was to assess the quality of hatchery-reared larvae in comparison with those reared in the wild, and determine to which extension wild growing larvae are also affected by skeletal deformities. The main structures affected included those forming the axial skeleton, the caudal fin complex and both anal and dorsal fins, with the most prevalent anomalies affecting caudal vertebrae and arches. Hatchery-reared fish presented a higher incidence of deformities (79%) compared with the 19% observed in wild specimens. In wild postlarvae collected in Autumn no deformities were observed. This work clearly shows that wild Senegalese sole present less skeletal deformities than those hatchery-reared during larval stages, indicating a selective mortality of wild deformed fish and/or an effect of aquaculture-related rearing conditions in the development of skeletal deformities in sole.

Fisheries and aquaculture implications of a meristic character in wild postlarvae of the shrimp, Litopenaeus vannamei (Boone, 1931) (Decapoda, Penaeoidea)

Worldwide, at least eight species of penaeid shrimp are involved in aquaculture operations (Bailey-Bruck & Moss, 1991) and the undiscriminating exploitation of wild shrimp postlarvae in offshore areas for stocking aquaculture ponds is a common practice that works against the industrial fishery’s interest. In order to minimize the possible damage created by a massive extraction of wild postlarvae from natural recruiting areas, it is imperative to establish certain management rules to ensure the success of both fishing and aquaculture activities. The tropical regions of the eastern Pacific and the Indo-Pacific represent an ideal environmental setting in which a selective strategy of extraction of wild shrimp postlarvae can be implemented for aquaculture purposes. In this region, nearly a billion shrimp postlarvae are annually collected to meet the increasing demand of private aquaculture enterprises that involve multimillion dollar investments with a high social impact. When fishing managers are confronted with such a conflict, rather than facing the need for optimizing the exploitation of the resources of wild shrimp postlarvae, they opt for the construction of costly laboratory rearing facilities for obtaining shrimp postlarvae. The main advantages of having such facilities are the year-round availability of shrimp postlarvae, and the guarantee of their sanitary quality standards. However, this practice, in addition to raising postlarval production costs, also undermines the rational use of a valuable natural resource (i.e., shrimp postlarvae) seriously affecting the economy of the local population by

Effects of temperature, density, and diet on development, survival, settlement synchronism, and fatty acid profile of the ornamental shrimp Lysmata seticaudata

The effects of different rearing temperatures, densities, and diets on the larval development, survival to metamorphosis, settlement synchronism, and fatty acid profile of the ornamental shrimp Lysmata seticaudata were evaluated. Survival of larvae raised at 20 °C was not significantly different (average±standard deviation) (94.8±4.5%) from that of those raised at 26 °C (85.3±9.5%), and presented significantly longer larval durations (31.8±1.0 days) than the ones raised at 26 °C (19.5±1.3 days). Larvae starved in zoea I displayed significantly lower survival (64.7±10.0%), and higher numbers of larvae remained in the last zoeal stage and died before metamorphosing. Larvae fed newly hatched Artemia nauplii, Artemia metanauplii or enriched Artemia metanauplii displayed similar survival (85.3±9.5%, 81.3±5.9%, and 75.5±2.1%, respectively) and similar larval stage durations. Larvae cultured at rearing densities of 10, 20, and 40 larvae l −1 showed similar survival rates (85.3±9.5%, 88.0±1.8%, and 86.8±5.4%, respectively). When cultured at 40 larvae l −1, a significantly higher proportion of larvae remained in the last zoeal stage (13.5±5.9%) 15 days after the settlement of the first postlarva. The survival of larvae fed newly hatched Artemia nauplii, or fed newly hatched Artemia nauplii until zoea V and switched to enriched Artemia metanauplii until settlement did not differ significantly (86.8±5.4% and 87.0±6.0%, respectively). Both treatments showed similar proportions of late stage larvae that did not metamorphose by the 15th day following the first settled postlarva. With the exception of larvae starved in zoea I, and those cultured at 40 larvae l −1, that did not display any “mass settlement period,” settlement mainly occurred during the 3rd and the 7th day following the settlement of the first postlarva. The fatty acid content of postlarvae cultured under different temperatures (20 and 26 °C) and fed the same larval diet (newly hatched Artemia) were similar. With the exception of docosahexaenoic acid (DHA) content, postlarvae fed enriched Artemia metanauplii displayed similar fatty acid content to those displayed by postlarvae fed on newly hatched Artemia and Artemia metanauplii. Wild postlarvae displayed a significantly lower fatty acid content (46.95±2.85 μg/mg dry weight), when compared to cultured organisms. These differences in fatty acid composition were more pronounced on saturated and monounsaturated fatty acids. Wild postlarvae always displayed a significantly higher DHA/EPA ratio (1.01±0.13), even when compared with that of postlarvae fed on enriched Artemia.

The effect of dietary protein and total energy content on digestive enzyme activities, growth and survival of Litopenaeus setiferus (Linnaeus 1767) postlarvae

The eAect of dietary protein and energy content on the activity of digestive enzymes (total proteinases, trypsin, chymotrypsin a-amylase and lipase), and growth and survival of Litopenaeus setiferus postlarvae was investigated under controlled conditions. There was a clear relationship between the diet fed to the postlarvae, growth and survival. Highest weight gain (2110 a 96.7%) was obtained with a 400 g kg )1 protein and low energy diet (13.9 kJ g )1 )( P < 0.05). The optimal protein to energy ratio (P/E) estimated was 28.8 mg of protein kJ )1 . Good survival was obtained with low energy diets containing between 200 and 400 g kg )1 protein and with high energy diets containing 300‐500 g kg )1 protein. Higher values for total proteinases, trypsin and a-amylase were obtained with the low energy, 400 g kg )1 protein diet. Chymotryptic activity was considerably lower than that of other proteinases and lipase activity was too low to be reliably measured with the turbidimetric method employed. Total proteinase activity was significantly lower than in experimentally grown postlarvae. The a-amylase activity was at least two orders of magnitude higher in wild postlarvae than in animals fed with the best experimental diet. Protein requirement was related to total energy content of the diet: best growth and digestive enzyme activity coincide with the low energy, 400 g kg )1 protein diet. These results suggest that dietary carbohydrates cannot spare protein because growth rates obtained with diets containing 200‐300 g kg )1 protein (337 and 226 g kg )1 dextrin content, respectively) were significantly lowered.

Fatty acids of wild and cultured Penaeus vannamei larvae from Ecuador

The main fatty acids of total lipid from wild and cultured postlarvae-10 (PL-10) of Penaeus vannamei obtained throughout 1 year from five different sampling sites along the Ecuadorian shore and four shrimp hatcheries, were analysed by gas-liquid chromatography. Cultured larvae showed higher levels of 18:3 n − 3 but lower levels of 20:5 n − 3 and 22:6 n − 3 than the wild ones. The fatty acid profile of wild postlarvae had a higher degree of unsaturation during the dry colder season than during the wet and hotter winter months. Wild and cultured postlarvae were clearly separated when the total lipid fatty acid results were introduced in a multivariate discriminant analysis model.

Identification of Wild Postlarvae of the Penaeid Shrimps, Genus &lt;i&gt;Penaeus&lt;/i&gt;, in the Pacific Coast of Central America

Identification of Wild Postlarvae of the Penaeid Shrimps, Genus &lt;i&gt;Penaeus&lt;/i&gt;, in the Pacific Coast of Central America

Morphology of Postlarvae of the Whiteleg Shrimp Penaeus vannamei.

Postlarvae of known parentage of Penaeus vannamei were reared in a laboratory. Their morphological characters were sequentially described, and compared with those of wild specimens and with previous descriptions. Differences in relative rostral length and in size at the first appearance of the spine and spinules have been detected between reared and wild postlarvae. A similarity in morphology was confirmed by a comparison with previous studies, but a difference in the ratio of antennular flagella, which was a subgeneric criterion of penaeid postlarvae, was revealed. The relative growth of carpus was compared between specimens in different localities, and the similarity in this growth was revealed.

Relative Growth of Penaeid Postlarvae as a Useful Tool for Identification.

Postlarvae of penaeid prawns were collected in coastal waters. It was revealed that the relationship between the lengths of carapace and body parts such as the 6th abdominal somite or 3rd pereiopod was linear, and the difference in that relationship between species was supposed to be applicable for the identification of postlarvae. From this viewpoint, examinations and rearing experiments on wild postlarvae were carried out. It was revealed that the relative growth of carpus of the 3rd pereopod facilitated the identification of wild postlarvae, especially those with close similarities in morphology. The introduction of this new criterion is concluded to be useful for distinguishing species.

Effects of Time of Day, Water Temperature, and Water Velocity on Swimming by Postlarvae of the American Lobster,Homarus americanus

Swimming speeds and swimming behavior of laboratory-reared and wild postlarvae (larval stage IV) of the American lobster, Homarus americanus, were observed in tanks of still water and in a linear flume. Mean swimming speeds ranged from about 7 cm∙s−1in the "claws-apart" swimming mode to 13.2 cm∙s−1in the streamlined, "claws-together" mode. In the flume, the total time spent swimming during a 30-min test period decreased as water velocity increased from 8 to 14 cm∙s−1. The time spent swimming was greater during the day than at either dusk or night. Postlarvae spent very little time swimming at 15 °C but significantly more at 21 °C. Wild postlarvae were larger, heavier, and swam more rapidly than laboratory-reared postlarvae. Rapid, directional swimming by postlarval lobsters may play a role in determination of distribution and recruitment to benthic populations.