Carapace mineralization and hepatopancreatic indices in natural and cultured populations of marron (Cherax tenuimanus) in Western Australia

Abstract

Marron (Cherax tenuimanus) were sampled from three wild populations in south-western Western Australia (Warren River, Donnelly River and Gardner River) and from five farmed populations in south-western, lower-western and central-western Western Australia. Mean calcium concentrations in the carapace were higher in wild populations (from 182320 to 213140 mg kg-1 dry matter) than in farmed populations (from 141960 to 182090 mg kg-1). The average calcium concentrations in the carapace were two-thirds those of other freshwater crayfish species. Mean carapace magnesium concentrations varied from 970 to 1880 mg kg-1 with no evident difference between wild and farmed populations. The proportion of calcium and magnesium in carapace inorganic matter varied from 54% to 78% and from 0·32% to 0·75%, respectively, being higher in the wild than in the farmed populations. With minor exceptions, carapace mineralization parameters correlated positively with calcium, magnesium and hardness of the water, and negatively with water pH. The wet hepatosomatic index, 4·5–6·0%, and the dry hepatosomatic index, 1·3–2·5%, were both higher in the farmed than in the wild populations, indicating better condition in the farmed marron. Hepatopancreas moisture concentration varied inversely with hepatosomatic index, ranging from 56·2% to 71·9%.

The effect of calcium concentration on the calcification of Daphnia magna

“…D. magna reared at 0.063 mM Ca are reported to have a Ca content in the range 2.8-5.4% of dry weight (Havas 1985), increasing to 7.7% of dry weight at 0.11 mM Ca (Cowgill 1976), which agrees well with our results. Studies of freshwater decapods also confirm a correlation between water Ca and animal Ca content (France 1987;Jussila 1997).…”

Dietary supplementation of mannan oligosaccharide improves the immune responses and survival of marron, Cherax tenuimanus (Smith, 1912) when challenged with different stressors

“…Total number of haemocytes, proportion of haemocyte types, bacteraemia and haemolymph clotting time have been used as indicators of health of crustacea [29,[37][38][39][40][41][42][43][44]. Recently, neutral red retention (NRR) assay has also been used to assess the immune status of shellfish by measuring the dye retention time of lysosomal membranes [45].…”

Health Status of Marron, Cherax cainii (Austin, 2002) Fedcustomized Probiotic Bacillus mycoides

“…Our previous work also demonstrated that B. mycoides significantly improved the intestinal bacterial population of marron compared to the commercial probiotic strains [46]. Modulation of GIT bacterial population and restoration of a normal microbiota constitutes the key components to maintain good health throughout the development stages of the animals [57] and this a stable commensal microbiota is part of the natural resistance to infections [25].…”

“…Measurement of THC followed the established methods described by [46]. In brief, 0.5 mL of haemolymph withdrawn from the second last ventral segment of marron placed into a haemocytometer (The Neaubauer Enhanced Line, Munich, Germany) counting chamber and immediately viewed under 100-fold magnification of camera-equipped microscope and images were taken for later THC counts.…”

“…The present study evaluated the effect of feeding duration using a marron Cherax caiini host origin strain, Bacillus mycoides [44,45] with previously demonstrated health benefits Ambas et al [46][47][48] by measuring intestinal bacterial population, hepatosomatic index (Hiw), total haemocyte count (THC), haemolymph bacteria (bacteraemia), glutathione peroxide (GPx) enzyme activity and survival rate.…”