Morphological, chemical and growth patterns characterization in shells of Phorcus species along the northeastern coasts of Tunisia

This work is a characterization of the morphometry, the relative growth and the metal contamination degree of the shells of two species belonging to Phorcus genus along the northeastern rocky coasts of Tunisia. The gastropods were sampled from nine locations during the winter 2017. Our findings suggested a spatial morphometric variability probably linked to the extent of the continental shelf, the coasts’ geomorphology, the dynamics of water masses, the predation and the competition effects. Furthermore, the shell investigation allowed the study of the growth pattern and indicated that the development in shell size was faster than the increase in weight. Moreover, the use of Phorcus shells as bioindicators of long-term metal contamination seems to be of growing interest, due to their abundance, high longevity, easy sampling and ecobiological features, both in a scientific and ecosystem management perspective that aims to the establishment of conservation measures targeting marine coastal environments

The effect of organic and conventional production methods on sea bream growth, health and body composition: A field experiment

This study aimed to develop a better understanding of organic sea bream aquaculture production in Greece, in particular its consequences for fish growth, health and body composition, and to propose and update standards for sustainable organic sea bream farming. Gilthead sea bream were kept in sea cages at densities of 4 kg m–3 (organic) and 15 kg m–3(conventional), and were fed organically produced feed (45% crude protein, 14% fat) or conventional feed (46% crude protein, 17% fat). The amino acid profile of the conventional diet, particularly the lysine content, which is one of most important dietary amino acids for sea bream, appeared to be unsatisfactory. “Organic” sea bream stored less fat content in their white muscle than the conventional sea bream. The liver lipid content was lower and the hepatosomatic index was higher for the organic sea bream. The microbiological analysis showed that both Enterobacteriaceae and Escherichia coli on the skin were below the enumeration detection limit in both the organic and conventional sea bream. Total viable counts on the skin and muscle of both the organically and conventionally cultured sea bream were approximately 3 log cfu g–1, which is well below the acceptable limit (7 log cfu g–1) for marine species. The results showed that the combination of a low stocking density and feed with a different ingredient composition but similar nutritional value resulted in similar growth rates and nutrient profiles of the final product. Further research on nutrition is required to provide information on setting the appropriate standards for organic sea bream aquaculture to ensure that the final product is in line with the consumers’ preferences

Size dependent metal concentrations in two marine gastropod species

The effect of size on the accumulation of Cd, Cr, Cu, Mn, Ni, Fe and Zn in the muscle and viscera of the gastropods Monodonta turbinata and Cerithium vulgatum was investigated. The concentration of the essential metals Cr, Mn and Ni and the non-essential metal Cd decreased with increasing size in both of the species and tissues. The concentration of the essential metals Cu, Fe and Zn, showed a less constant relation with size. © 1994 Kluwer Academic Publishers

Monodonta Turbinata (BORN); Toxicity and Bioaccumulation of Cu and Cu + Cr Mixtures

The effects of copper and chromium are studied on the cosmopolite marine prosobranch Monodonta turbinata (Born). The influence of Cu and of the mixture Cu + Cr was tested by the determination of the LC50 (48 h), the LT50, the respiration and bioaccumulation rates. The tested concentrations of metals caused a significant reduction of the respiration rate of Monodonta. Cu accumulates progressively in the tissues of the prosobranch proportionally to the Cu concentrations of the tested media. In all experiments [LC50 (48 h), LT50, oxygen consumption and bioaccumulation] when Cu and Cr act jointly, an antagonism is observed: the mixtures caused less pronounced effects than Cu and Cr acting alone. Generally Monodonta was found to be much more sensitive to Cu than other benthic species. © 1993, Taylor & Francis Group, LLC. All rights reserved