Analysis of the impact of Holothuria scabra intensive farming on sediment

• Published in: Cahiers de biologie marine Vol. 54; no. 4; pp. 703 - 711
• Main Authors: PLOTIEAU, Thomas, BAELE, Jean-Marc, VAUCHER, Romain, HASLER, Claude-Alain, KOUDAD, Dunia, EECKHAUT, Igor
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Roscoff Ed. de la station biologique 01-10-2013
• Subjects: Animal and plant ecology; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; Biological and medical sciences; Echinodermata; Fundamental and applied biological sciences. Psychology; General aspects; Holothuria scabra; Holothurioidea; Invertebrates; Marine; Sea water ecosystems; Synecology; ISW, Indian Ocean, Madagascar; Organic matter; Sea cucumber; Holothuria scabra; Sediment; Echinodermata; Intensive farming; Sediments; Marine environment; Holothuroidea; Hydrobiology; Analysis; Bacteria; Invertebrata; Aquaculture
• ISSN: 0007-9723; 2262-3094

We analysed the impact of intensive Holothuria scabra farming by comparing various parameters of the sea cucumber food (i.e. the upper layer of the sediment) inside and outside the pens of two farms in the south-west of Madagascar. Our analyses showed that: (i) the proportion of the finest grain size fraction (< 250 mu m) decreased from 5 to 14%, (ii) the global carbonate proportion decreased by 5%, (iii) aragonite was the carbonate type most affected by holothurians, followed by calcite and magnesian calcite, (iv) the total organic matter did not vary significantly, (v) the number of bacteria decreased by up to 50%, and (vi) the concentration of photosynthetic microorganisms fell by up to 22%, within sea farm pens. Based on these results we suggest that fallow practice should be considered in the future for holothuri-culture.Original Abstract: L'impact de l'elevage intensif d'Holothuria scabra sur le sediment a ete etudie par comparaison de plusieurs elements alimentaires de cette espece (i.e. provenant de la couche superieure du sediment) a l'interieur et a l'exterieur des enclos d'elevage. Cette etude a ete realisee sur le sediment de deux fermes dans le sud-ouest de Madagascar. Nos analyses demontrent que: (i) la proportion de grains de petite taille (< 250 mu m) diminue de 5 a 14%, (ii) le taux de carbonates diminue de 5%, (iii) l'aragonite est le type de carbonates le plus affecte par l'activite des holothuries, suivie par la calcite et la calcite magnesienne, (iv) le taux de matiere organique ne differe pas significativement, (v) le nombre de bacteries diminue jusqu'a 50%, et (vi) la concentration de microorganismes photosynthetiques diminue jusqu'a 22%, a l'interieur des enclos d'elevage. Au vu de ces resultats, la pratique de jacheres devrait etre developpee a l'avenir en holothuriculture.