Lethal and sublethal effects of naphthalene and 1,2-dimethylnaphthalene on the marine copepod <Emphasis Type="Italic">Paracartia grani</Emphasis>

Here we evaluate the effects of two quantitatively very important components of the water soluble fractions of fuel oils (naphthalene and 1,2-dimethylnaphthalene, hereafter NAPH and C2-NAPH, respectively) on the survival, feeding and egg production rates, and viability of eggs of the coastal copepod Paracartia (Acartia) grani. Acute toxicity responses resulted in lethal concentrations (LC50) of 2,535 and 161 μg l⁻¹ for NAPH and C2-NAPH, respectively, with no evidence of narcotic effects. Hydrocarbon-specific differences in the toxicity response indicate that sublethal effects (EC50) on feeding by C2-NAPH were likely driven by induced mortality, whereas NAPH has direct negative effects on feeding. Sublethal effects on egg production rates followed a similar detrimental pattern to the one exhibited by feeding rates, suggesting that the lower egg production rates were mediated by the decrease in feeding rates. At the exposure time tested (24 h), the 50% reduction effective concentrations (EC50) determined for sublethal effects were relatively high in comparison with hydrocarbons’ concentrations found under natural circumstances. Long exposure (4 days) of P. grani adults to the tested hydrocarbons at concentrations well below the recorded EC50, however, had no significant effects on feeding, egg production and hatching rates. The viability of the eggs was either not affected or only slightly influenced when healthy eggs were incubated under very high concentrations (up to 6,400 and 700 μg l⁻¹ NAPH and C2-NAPH, respectively). The significance of the effects of oil spills on marine zooplankton communities is discussed in light of the results presented in this study.     

Diffusive gradient in thin films with open and restricted gels for predicting mercury uptake by plants

Environmental Chemistry Letters - The presence of mercury (Hg) in the environment is a major concern because mercury is toxic for living organisms. Estimating the Hg toxicity of environmental...     

Influence of hydrodynamic conditions on the production and fate of Posidonia oceanica in a semi-enclosed shallow basin (Stagnone di Marsala,Western Sicily)

An integrated approach using hydrodynamic and transport numerical models, lepidochronology and stable isotope analysis was used to investigate how local hydrodynamic conditions influence the primary production and fate of the seagrass Posidonia oceanica in a Mediterranean semi-enclosed marine system (Stagnone di Marsala). The water mass exchange aptitude of different sectors of the basin was analysed, and data collected were used to select two sectors (colonized by Posidonia oceanica showing the lowest and highest water exchange values) for biological analyses. According to the mean dispersal coefficient differences simulated by the hydrodynamic model, growth rate and primary production of P. oceanica differed between sectors, with average values lower in the central sector where water exchange is lower than in the southern sector. Although P. oceanica coverage and primary production were higher in the southern sector, carbon and nitrogen stable isotope analysis suggests that the transfer of seagrass organic matter to higher trophic levels of the food web was higher in the central sector. The possibility of a link between hydrodynamism, production and fate of organic matter is proposed to explain the observed patterns.     

The Mediterranean intertidal habitat as a natural laboratory to study climate change drivers of geographic patterns in marine biodiversity

Nylon bags containing yellow leaves of Rhizophora apiculata and Avicennia marina, were immersed for 80 days from August to October, 1996. the decomposing leaves were collected every 10 days and analysed for dry weight loss and six biochemical parameters: tannins, total amino acids, total sugars, total nitrogen, total lipids and fatty acid profile. the leaf weight initially decreased very rapidly by about 50% of the start in two species of mangroves within 10 days. Similar changes were observed with tannins, total amino acids and sugars. However, the concentration of nitrogen increased significantly with decomposition. There was no significant change in total lipid and fatty acid profile. the highest concentration of fatty acid in the decomposing leaves was palmitic acid (16:0). Unsaturated fatty acids such as, 18:1 w7c and 18:1 w9c were found to be present in decomposing leaves of both species.     

Climate change,marine policy and the valuation of Mediterranean intertidal ecosystems

This commentary describes a gap in the qualitative and quantitative knowledge of the provision of benefits to humans from the intertidal ecosystems of the Mediterranean and offers a framework for quantification of the benefits provided by these systems. The identification of such benefits, understanding their spatial distribution and their subsequent quantification will be critical to the design of policy responses to future climate change, sea level rise and seawater acidification. A baseline understanding of the current state of ecosystem functions, as well as of the provision of related ecosystem services, is therefore needed. Further, researchers must strive to generate forecasts of the changes in these functions and services conditional on policy responses and the range of expectations for climate change.     

2,3,7,8-Substituted PCDDs and PCDFs in sea lion (Otaria flavescens) skin biopsies from two South-western Atlantic populations

Congener specific 2,3,7,8-chlorinated PCDDs and PCDFs were determined in skin biopsies taken from sea lions (Otaria flavescens) living in two areas of the South-western Atlantic on the coast of Argentina (Mar del Plata and Punta Bermeja). This is the first report on PCDDs and PCDFs in sea lion skin biopsies from the southern hemisphere. Differences were found in the congener pattern according to the sampling area. Animals living in the polluted area (Mar del Plata harbour) had detectable levels of all seventeen 2,3,7,8-substituted congeners. Sea lions living in a control environment (Punta Bermeja, Patagonia) only exhibited 5 detectable congeners out of all seventeen 2,3,7,8-substituted congeners. However, total levels were low in both colonies studied. These data are consistent with previous work which has indicated that dioxins occur at relatively low levels in marine mammals, possibly due to rapid catabolism or elimination.