Assessment of metal concentrations in commercially important fish species in Black Sea.

In the present study, concentrations of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were measured in the muscle, gill, and gonads of the pelagic fish species Trachurus mediterraneus, Engraulis encrasicolus ponticus, and Sprattus sprattus that are important both commercially and for the ecosystems in the Black Sea. The samples were collected during 2011. The metals were determined using inductively coupled plasma mass spectrometry (ICP-MS) following an acid digestion. The highest concentrations of As, Cd, Co, Cr, Cu, Pb, and Zn were found in E. encrasicolus ponticus, whereas the greatest concentrations of Ni were found in T. mediterraneus and Mn in S. sprattus. Results showed that average metal concentrations in the tissues of T. mediterraneus, E. encrasicolus ponticus, and S. sprattus decreased in the order gill > gonad > muscle, gonad > gill > muscle, and gill > gonad > muscle, respectively, for the three species. When metal concentrations of fish tissues were compared between fish gender, there were only statistical differences in the gonads of the studied fish species (p < 0.05). The present study demonstrated that the metals have different correlations with condition factor (CF) and gonadosomatic index (GSI) of the fish species. Cr showed statistically important positive correlation to the GSI in male T. mediterraneus. Co showed statistically important positive correlation to CF in female E. encrasicolus ponticus, and also Co and Cd showed correlation to CF in male T. mediterraneus. Cd concentrations in the muscle tissues of the fish species were above the maximum acceptable concentration for human consumption

Status and recommendations for sustainable freshwater aquaculture in Brazil

Brazil is a megadiverse country and is participant of fundamental environmental agreements for biodiversity conservation. However, the internal politics and the cultures that affect negatively the ecological integrity in Brazilian freshwater need to be improved on the condition of sustainable management. Scientific community, the government and stakeholders are in constant conflicts of goals. Meanwhile, the current model for Brazilian aquaculture shows problems of ecological impact due to the lack of appropriated planning and legislation to the aquatic biota. The non-recognition of sustainable census incorporated in its environmental politics reflects in an archaic and unsustainable management, with the following characters: a non-specific approach for technical management, the indiscriminate use of interspecific hybrids and non-native species and the lack of skilled labour. The potential impact on native species and the introduction of pathogens are the main negative effects on aquatic biota. This way, the aim of this article is to elucidate the conflicts of interests and ecological effects of fish aquaculture in Brazil, besides providing good practices and sustainable alternatives for management.Departmento de Morfologia Instituto de Biociências Universidade Estadual PaulistaLaboratório de Ecologia Pesca e Ictiologia Departamento de Biodiversidade Programa de Pós-Graduação em Aquicultura e Desenvolvimento Sustentável Universidade Federal do ParanáLaboratory of Ecology and Conservation Department of Environmental Engineering Federal University of ParanáDepartment of Agroecology Flakkebjerg Research Centre Aarhus UniversityLaboratório de Ecologia de Peixes e Invasões Biológicas Departamento de Biologia Animal e Vegetal Centro de Ciências Biológicas Rodovia Celso Garcia Cid Universidade Estadual de LondrinaWater Research Group Unit for Environmental Sciences and Management Potchefstroom Campus North-West UniversityDepartment of Parasitology Institute of Biosciences São Paulo State University (UNESP)Laboratório de Genética de Peixes Faculdade de Ciências Universidade Estadual PaulistaFederal Technological University of Paraná (UTFPR)Department of Biology and Animal Science School of Engineering São Paulo State University (UNESP)Departmento de Morfologia Instituto de Biociências Universidade Estadual PaulistaDepartment of Parasitology Institute of Biosciences São Paulo State University (UNESP)Laboratório de Genética de Peixes Faculdade de Ciências Universidade Estadual PaulistaDepartment of Biology and Animal Science School of Engineering São Paulo State University (UNESP

Population collapses in introduced non-indigenous crayfish

Invasive species often have instable population dynamics and are known to collapse or oscillate heavily after passing through the initial lag/growth phases. Long-term data-series documenting these fluctuations are however rare. We use long-term (starting in the early 1960s), semi-quantitative data on the invasive signal crayfish (Pacifastacus leniusculus), capturing its population development after introduction in 44 Swedish lakes. In total 18 (41 %) of these populations had experienced a collapse. A stepwise discriminant function analysis including 20 different ecological or physicochemical characteristics identified three variables explaining collapses in the following order: stocking year, population age and mean air temperature. Populations stocked in the 1980s were more likely to collapse than populations stocked in the 1970s. Lakes with collapses were located in areas with 0.4 A degrees C higher yearly mean air temperatures than the still viable populations. Collapses also depended on the time phase of the population and started to occur 12 years after stocking and were most frequent in the interval 16-20 years after stocking and after 11-15 years duration of the established phase with harvestable densities. An analysis of prevalence and pathogen load of Aphanomyces astaci was conducted in eight of the studied populations. A. astaci was present in all populations but neither the level of prevalence nor the pathogen load in infested specimens differed significantly between lakes with collapses and lakes without. Our results highlight the potential sensitivity and instability of introduced crayfish. The importance of density-dependence and temperature suggest that both climate variability and/or fisheries can influence these processes