Bacterial diversity of the sediments transiting through the gut of <i>Holothuria scabra</i> (Holothuroidea; Echinodermata)

This work analyzes bacterial diversity of sediments transiting through the gut of Holothuria scabra which is an important bioturbator in tropical shallow waters. This edible holothurian species has a social and economic importance for coastal populations in many developing countries. Bacterial biodiversity was analyzed by sequencing the 16S rRNA of bacterial cultures and clones. DAPI and FISH methods were used to determine and compare the number of bacteria found in the various gut compartments. A total of 116 phylotypes belonging to the ?-Proteobacteria (60.5 %), a-Proteobacteria (24.5 %), Bacteroidetes (6 %), Actinobacteria (2.75 %), Fusobacteria (1.75 %), Firmicutes (1.75 %), Cyanobacteria (1.75 %) and d-Proteobacteria (1 %) were identified. The number of bacteria is significantly greater (1.5×) in the foregut than in the ambient sediments. The number of bacteria significantly decreases in the midgut and remains stable until defecation. Some ?-Proteobacteria, especially Vibrio, are less affected by digestion than other bacterial taxa. The season has an impact on the bacterial diversity found in the sediments transiting through the gut: in the dry season, ?-Proteobacteria are the most abundant taxon, while a-Proteobacteria dominate in the rainy season. Vibrio is the most frequent genus with some well-known opportunistic pathogens like V. harveyi, V. alginolyticus and V. proteolyticus. Findings show that sediment-associated microbial communities are significantly modified by H. scabra during their transit through the gut which supports the view that holothurians play a substantial role in the structuring of bacterial communities at the sediment–seawater interface

Isotopic tracing of sediment components that are assimilated by epibiontic juveniles of Holothuria scabra (Holothuroidea)

Despite H. scabra’s wide distribution and status as one of the best candidates for sustaining the development of tropical sea cucumber aquaculture, very few data are available regarding the organic fraction it assimilates in practice. In this study we report experimental results where H. scabra’s diet was supplemented with various 15N-labelled organic fractions of sediment. We used juveniles weighing between 38- 88 mg at the beginning of the experiment (ca. 2 cm long and 30 days old). Their growth was measured over a four week period and their 15N composition recorded. The results showed that H. scabra juveniles assimilated all added organic components from both dissolved and particulate fractions of the sediment. Bacteria seem to be an important food source for juveniles, even more so than microphytobenthos (diatoms).Holothurian aquaculture and nutritio

Isotopic tracing of sediment components assimilated by epibiontic juveniles of <i>Holothuria scabra</i> (Holothuroidea)

Despite Holothuria scabra's wide distribution and status as one of the best candidates for sustaining the development of tropical sea cucumber aquaculture, very few data are available regarding the organic fraction it assimilates in practice. In this paper we report experimental results where H. scabra's diet was supplemented with various 15N-labelled organic fractions of sediment. We used juveniles weighing between 38 and 88 mg at the beginning of the experiment (~2 cm long and 30 days old). Their growth was measured over a four-week period and their 15N composition recorded. The results showed that H. scabra juveniles assimilated all added organic components from both dissolved and particulate fractions of the sediment. Bacteria seem to be an important food source for juveniles, even more so than microphytobenthos (diatoms)

Problems related to the farming of Holothuria scabra (Jaeger 1833)

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The effect of food quality and rearing density on the growth and survival of epibenthic juveniles of the sea cucumber Holothuria scabra

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Processing and marketing of holothurians in the Toliara region, southwestern Madagascar

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Madagascar Holothurie SA: la première entreprise commerciale axée sur l’aquaculture des holothuries à Madagascar Bêche-de-mer

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Madagascar Holothurie SA: The first trade company based on sea cucumber aquaculture in Madagascar

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