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Abstract
The behavioural response of the mud lobster, Thalassina anomala Herbst, 1804, to different trapping devices (TD), was studied in the mangrove areas of Sibuti, Sarawak, East Malaysia. Nine different TDs were deployed in this study. Observations revealed that there were no differences in response, neither due to the various types of mound, or as a result of the different TDs: rather, the lobsters either avoided, or obstructed those TDs. Detailed observations revealed that the mud lobsters showed skilled avoidance by either moving freshly dug, moist mud into the TD-types made of bamboo and plastic, or moved the fishing net out of the burrow when it was obstructed by such a type of TD. The damaged parts of the mound caused by deployment of the TD were successfully reconstructed or rebuilt by the mud lobster, using moist mud from the bottom of their tunnel. There was no particular period determined, i.e., neither by day nor at night, when the mud lobsters repaired or rebuilt their opened or otherwise disturbed burrows.
Abstract
Mesocyclops leuckarti is a zooplankton that is potentially suitable as a live food for freshwater fish larvae. Aquaculture farmers often struggled to create nutritious live feed to maximize the production of larval fish. This study aimed to determine the effects of different enrichments on life-table parameters, protein, lipid and fatty acid content of M. leuckarti when enriched with different dietary enrichments. In this study, five treatments for raising the copepod were compared: rice bran, soybean meal, Chlorella sp., Spirulina sp., and unenriched (control). The results showed that M. leuckarti after 16 days of cultivation enriched with rice bran produced a higher population density (53.3 ind/ml) and survival rate (97.4%) than when cultivated with any of the other diets. In terms of nutritional value, protein content was higher in M. leuckarti enriched with rice bran (52% DW) and soybean meal (53% DW). However, lipid content was highest in M. leuckarti enriched with rice bran (14% DW). Fatty acids, such as α-linolenic acid ALA (7.21%) and docosahexaenoic acid DHA (6.26%) were higher in M. leuckarti enriched with rice bran. Eicosapentaenoic acid EPA (7.16%) and arachidonic acid ARA (7.74%) were higher in M. leuckarti enriched with Chlorella sp. This study suggests that organic by-products are better sources for strengthening and improving the growth performance and life history of this copepod, and possibly also of zooplankton organisms in general.