Effects of fishery protection on biometry and genetic structure of two target sea cucumber species from the Mediterranean Sea

Sea cucumber fisheries are now occurring in most of the tropical areas of the world, having expanded from its origin in the central Indo-Pacific. Due to the overexploitation of these resources and the increasing demand from Asian countries, new target species from Mediterranean Sea and northeastern Atlantic Ocean are being caught. The fishery effects on biometry and genetic structure of two target species (Holothuria polii and H. tubulosa) from Turkey, were assessed. The heaviest and largest individuals of H. polii were found into the non-fishery area of Kusadasi, also showing the highest genetic diversity. Similar pattern was detected in H. tubulosa, but only the weight was significantly higher in the protected area. However, the observed differences on the fishery effects between species, could be explained considering the different percentage of catches (80% for H. polii and 20% for H. tubulosa)

An Ecosystem-Based Approach to Assess the Status of a Mediterranean Ecosystem, the Posidonia oceanica Seagrass Meadow

17 páginas, 8 tablas, 3 figurasBiotic indices, which reflect the quality of the environment, are widely used in the marine realm. Sometimes, key species or ecosystem engineers are selected for this purpose. This is the case of the Mediterranean seagrass Posidonia oceanica, widely used as a biological quality element in the context of the European Union Water Framework Directive (WFD). The good quality of a water body and the apparent health of a species, whether or not an ecosystem engineer such as P. oceanica, is not always indicative of the good structure and functioning of the whole ecosystem. A key point of the recent Marine Strategy Framework Directive (MSFD) is the ecosystem-based approach. Here, on the basis of a simplified conceptual model of the P. oceanica ecosystem, we have proposed an ecosystem-based index of the quality of its functioning, compliant with the MSFD requirements. This index (EBQI) is based upon a set of representative functional compartments, the weighting of these compartments and the assessment of the quality of each compartment by comparison of a supposed baseline. The index well discriminated 17 sites in the north-western Mediterranean (French Riviera, Provence, Corsica, Catalonia and Balearic Islands) covering a wide range of human pressure levels. The strong points of the EBQI are that it is easy to implement, non-destructive, relatively robust, according to the selection of the compartments and to their weighting, and associated with confidence indices that indicate possible weakness and biases and therefore the need for further field data acquisition.Peer reviewe

Seasonal variations of digestive enzymes in sea cucumbers (Holothuria tubulosa, G. 1788) under culture conditions

Emiroglu, Dilek/0000-0001-8371-6407WOS: 000504439600001PubMed: 31880099Sea cucumber, Holothuria tubulosa (Gmelin, 1788), is an economically valuable species due to its rich nutrients content that being exported in Turkey. However, culture of this species is difficult due to a lack of knowledge. the main objective of this study is to investigate seasonal activities of main digestive enzymes (protease, lipase, and amylase) for nutritional requirements. in this sense, sea cucumbers were stocked in the glass aquarium and sediment was 10 cm. It was replaced monthly and enriched (1% of the living individual weight) by dried Sargassum sp. Total protease and amylase enzymes have shown higher activity compared to lipase. All three enzyme activities were maximum in the summer and minimum in the winter. in summer, the highest measured total protease, amylase, and lipase activity values were 6.45 +/- 0.66, 6.77 +/- 0.72, and 2.78 +/- 0.32 U/mg per protein, respectively. in winter, the lowest total protease, amylase, and lipase activity values were measured as 2.03 +/- 0.16, 1.14 +/- 0.14, and 0.12 +/- 0.01 U/mg per protein, respectively. As a conclusion of the study, seasonal expression of the main digestive enzymes was strictly dependent on water temperatures and food abundance and also it was ideal to feed this species with food containing high protein and carbohydrate under appropriate temperatures for commercial culture

Phosphorus acquisition by citrate- and phytase-exuding Nicotiana tabacum plant mixtures depends on soil phosphorus availability and root intermingling

Citrate and phytase root exudates contribute to improved phosphorus (P) acquisition efficiency in Nicotiana tabacum (tobacco) when both exudates are produced in a P deficient soil. To test the importance of root intermingling in the interaction of citrate and phytase exudates, Nicotiana tabacum plant-lines with constitutive expression of heterologous citrate (Cit) or fungal phytase (Phy) exudation traits were grown under two root treatments (roots separated or intermingled) and in two soils with contrasting soil P availability. Complementarity of plant mixtures varying in citrate efflux rate and mobility of the expressed phytase in soil was determined based on plant biomass and P accumulation. Soil P composition was evaluated using solution (31) P NMR spectroscopy. In the soil with limited available P, positive complementarity occurred in Cit+Phy mixtures with roots intermingled. Root separation eliminated positive interactions in mixtures expressing the less mobile phytase (Aspergillus niger PhyA) whereas positive complementarity persisted in mixtures that expressed the more mobile phytase (Peniophora lycii PhyA). Soils from Cit+Phy mixtures contained less inorganic P and more organic P compared to monocultures. Exudate-specific strategies for the acquisition of soil P were most effective in P-limited soil and depended on citrate efflux rate and the relative mobility of the expressed phytase in soil. Plant growth and soil P utilization in plant systems with complementary exudation strategies are expected to be greatest where exudates persist in soil and are expressed synchronously in space and time