Experimental evaluation of co-culture of juvenile sea cucumbers, Holothuria scabra (Jaeger), with juvenile blue shrimp, Litopenaeus stylirostris (Stimpson) Auteur(s) : Purcell, S Patrois, Jacques Fraisse, N Éditeur(s) : Blackwell science Résumé : The co-culture of juvenile sea cucumber Holothuria scabra (Jaeger), or 'sandfish', with juvenile blue shrimp Litopenaeus stylirostris (Stimpson) was tested by growing groups in co-culture and monoculture for 3 weeks in tanks with enriched sand substratum. Feed was supplied on trays, accessible only to shrimp. Survival of shrimp and sandfish was high in all treatments (73-100%). Growth of shrimp did not differ between monoculture and co-culture, but sandfish grew significantly slower in co-culture (P=0.03), although their sand burying and surface foraging were apparently unaffected by shrimp (P=0.76). However, shrimp increased the levels of total ammonia-N in tanks, which related inversely with sandfish growth (P=0.04). Conversely, sandfish did not appear to lower the water quality for shrimp culture. While sandfish bioturbate sediments and eat organic deposits, the juveniles did not significantly reduce the organic content of sand in tanks. Co-culturing juveniles of the two species in earthen ponds appears feasible, with no detriment to shrimp production, presenting a cost-effective method for growing sandfish to larger sizes for restocking. These findings underpin further studies to test the viability of commercial co-culture of sandfish with blue shrimp at later stages in the production cycle of shrimp. Aquaculture Research (1355-557X) (Blackwell science), 2006-03 , Vol. 37 , N. 5 , P. 515-522 Droits : 2006 Blackwell Publishing, Inc. http://archimer.ifremer.fr/doc/2006/publication-1356.pdf DOI:10.1111/j.1365-2109.2006.01458.x http://archimer.ifremer.fr/doc/00000/1356/ | Partager |
Grow-out of sandfish Holothuria scabra in ponds shows that co-culture with shrimp Litopenaeus stylirostris is not viable Auteur(s) : Bell, J Agudo, N Purcell, S Blazer, P Simutoga, M Pham, Dominique Della Patrona, Luc Éditeur(s) : Elsevier Résumé : We examined the potential for producing the large numbers of sandfish (Holothuria scabra) needed for restocking programmes by co-culturing juveniles with the shrimp Litopenaeus stylirostris in earthen ponds. Our experiments in hapas within shrimp ponds were designed to detect any deleterious effects of sandfish on shrimp, and vice versa. These experiments showed that a high stocking density of juvenile sandfish had no significant effects on growth and survival of shrimp. However, survival and growth of sandfish reared with shrimp for 3 weeks were significantly lower than for sandfish reared alone. Increased stocking density of shrimp also had a significant negative effect on survival and/or growth of sandfish. A grow-out trial of juvenile sandfish in 0.2-ha earthen ponds stocked with 20 shrimp post-larvae m(-2), and densities of sandfish between 0.8 and 1.6 individuals m(-2), confirmed that co-culture is not viable. All sandfish reared in co-culture were dead or moribund after a month. However, sandfish stocked alone into 0.2-ha earthen ponds survived well and grew to mean weights of similar to 400 g within 12 months without addition of food. The grow-out trial demonstrated that there is potential for profitable pond farming of sandfish in monoculture. Further research is now needed to identify the optimal size of juveniles, stocking densities and pond management regimes. (C) 2007 Elsevier B.V. All rights reserved. Aquaculture (0044-8486) (Elsevier), 2007-12 , Vol. 273 , N. 4 , P. 509-519 Droits : 2007 Elsevier B.V. All rights reserved. http://archimer.ifremer.fr/doc/2007/publication-3590.pdf DOI:10.1016/j.aquaculture.2007.07.015 http://archimer.ifremer.fr/doc/00000/3590/ | Partager |
Adaptive aspects of phenotypic plasticity in echinoderms Auteur(s) : Ebert, Ta Éditeur(s) : Gauthier-Villars Résumé : Echinoderms show phenotypic plasticity in which variation in environmental conditions elicit graded reaction norms of morphological change. With the sea urchin Strongylocentrotus purpuratus under laboratory conditions, decreases in available food caused decreases in dry weights of the gonad and gut coupled with increases in the mass of Aristotle's lantern and length of the demi-pyramids. Spine clipping caused increased spine growth as well as decreases in the gut and gonad masses. Survival rate remained unchanged over a range of feeding and clipping treatments. In the field, at Sunset Bay, Oregon, well-fed sea urchins, with relatively small demi-pyramids, showed survival rates similar to poorly fed sea urchins that had large demi-pyramids. The wide range of morphological change, coupled with the narrow range of-change in survival, suggests that morphological plasticity buffers survival and hence would increase fitness. Phenotypic plasticity shown by other sea urchins includes changes in the relative sizes of Aristotle's lantern in Diadema antillarum and Echinometra mathaei and seasonal variation in the density of pedicellariae in Echinus esculentus. Variation in body size of echinoids and asteroids in different habitats and variation in number of arms in crinoids also may be examples of adaptive plasticity. Seasonal atrophy of internal organs in the sea cucumber Parastichopus californicus has been interpreted as an adaptive response to food limitation but, given the nature of responses in other echinoderms, such an interpretation seems unlikely and the significance of seasonal atrophy of organs in holothurians remains unknown. Oceanologica Acta (0399-1784) (Gauthier-Villars), 1996 , Vol. 19 , N. 3-4 , P. 347-355 Droits : info:eu-repo/semantics/openAccess http://archimer.ifremer.fr/doc/00094/20492/18187.pdf http://archimer.ifremer.fr/doc/00094/20492/ | Partager |