Using MixSIAR to quantify mixed contributions of primary producers from amino acid δ15N of marine consumers.

Estimations of the trophic position and the food web nitrogen baseline from compound-specific isotope analysis of individual amino acids (CSIA-AA) are challenged when the diet of consumer organisms relies on different proportions of vascular and non-vascular primary producers. Here we propose a method to infer such proportions using mixing models and the δ15N CSIA-AA values from marine herbivores. Combining published and new data, we first characterized CSIA-AA values in phytoplankton, macroalgae and vascular plants, and determined their characteristic ß values (i.e. the isotopic difference between trophic and source AA). Then, we applied MixSIAR Bayesian isotope mixing models to investigate the transfer of these isotopic signals to marine herbivores (molluscs, green turtles, zooplankton and fish), and their utility to quantify autotrophic sources. We demonstrated that primary producer groups have distinct δ15NAA fingerprints that can be tracked into their primary consumers, thus offering a rapid solution to quantify resource utilization and estimate ßmix values in mixed-sourced environments.

Assessing the toxicity of chemical compounds associated with land-based marine fish farms: the sea urchin embryo bioassay with Paracentrotus lividus and Arbacia lixula.

In aquaculture, disinfection of facilities, prevention of fish diseases, and stimulation of fish growth are priority goals and the most important sources of toxic substances to the environment, together with excretory products from fish. In the present study, embryos of two species of sea urchin (Paracentrotus lividus and Arbacia lixula) were exposed to serial dilutions of six antibiotics (amoxicillin (AMOX), ampicillin, flumequine (FLU), oxytetracycline (OTC), streptomycin (ST), and sulfadiazine [SFD]) and two disinfectants (sodium hypochlorite (NaClO) and formaldehyde [CH(2)O]). Alterations in larval development were studied, and the effective concentrations (ECs) were calculated to evaluate the toxicity of the substances. Both species showed similar sensitivities to all substances tested. Disinfectants (EC(50) = 1.78 and 1.79 mg/l for CH(2)O; EC(50) = 10.15 and 11.1 mg/l for NaClO) were found to be more toxic than antibiotics. AMOX, OTC, and ST caused <20 % of alterations, even at the highest concentrations tested. FLU was the most toxic to P. lividus (EC(50) = 31.0 mg/l) and SFD to A. lixula (EC(50) = 12.7 mg/l). The sea urchin bioassay should be considered within toxicity assessment-monitoring plans because of the sensitivity of larvae to disinfectants.

Implementation of a minimal set of biological tests to assess the ecotoxic effects of effluents from land-based marine fish farms.

Environmental monitoring plans (EMP) that include chemical analysis of water, a battery of bioassays and the study of local hydrodynamic conditions are required for land-based marine aquaculture. In this study, the following standardized toxicity tests were performed to assess the toxicity of effluents from eight land-base marine fish farms (LBMFFs) located on the northwest coast of Spain: bacterial bioluminescence (with Vibrio fischeri at 15 and 30 min), microalgal growth (with Phaeodactyllum tricornutum and Isochrysis galbana) and sea urchin larval development (with Paracentrotus lividus and Arbacia lixula). These bioassays were evaluated for inclusion in routine fish farm monitoring. Effective concentrations (EC(5), EC(10), EC(20), EC(50)) for each bioassay were calculated from dose-response curves, obtained by fitting the bioassay results to the best parametric model. Moreover, a graphical method of integrating the results from the battery of bioassays and classifying the toxicity was proposed, and the potential ecotoxic effects probe (PEEP) index was calculated. The bacterial bioluminiscence test at 30min, growth of I. galbana and larval development of A. lixula were found to be the most sensitive and useful tests. Graphical integration of these test results enabled definition of the ecotoxicological profiles of the different farms. The PEEP index, considering EC(20), efficiently reflected the toxic loading potential of LBMFF effluents. In conclusion, a battery of bioassays with species from different low trophic levels is recommended as a rapid and cost-effective methodology for assessing LBMFF discharges. The graphical integration method and the PEEP index are proposed for consideration in EMPs for such farms.

Use of macroalgae stored in an Environmental Specimen Bank for application of some European Framework Directives.

Different European Framework Directives have established a series of objectives for conservation of the coast, and monitoring tools must be made available to test compliance with these aims. In the present study the use of macroalgae deposited in an Environmental Specimen Bank was evaluated as a possible environmental tool for monitoring the coastal ecosystem. The concentrations of Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn in three species of the genus Fucus (Fucus spiralis, Fucus vesiculosus and Fucus ceranoides) were measured at sampling sites distributed along the coast of Galicia (NW Spain). In the period 1990-2001, the concentrations of the metals were higher in 1990 than in 2001, with the exception of: i) Mn in F. ceranoides and Fe in F. spiralis-F. vesiculosus, for which there were no differences between the sampling periods, and ii) Zn in F. vesiculosus and Fe in F. ceranoides, for which the concentrations were higher in 2001 than in 1990. In the period 2001-2007 concentrations of the metals were more stable, especially in F. ceranoides (e.g. Al, Fe, Hg, Ni and V). The concentrations were also more stable vin F. vesiculosus in 2005 (i.e. Al, Cr, Fe, Mn and Zn). The population density distributions are consistent with the results of the statistical tests. The results indicate that macroalgae of the genus Fucus may be useful for applying different European Framework Directives, given that the macroalgae are sufficiently sensitive to changes in concentrations of metals, and may be suitable for long-term monitoring and used for the detection of increased concentrations of metals (real-time monitoring).