Long-term sediment records reveal over three thousand years of heavy metal inputs in the Mar Menor coastal lagoon (SE Spain).

The Mar Menor lagoon combined high biological production and environmental quality, making it an important economic engine. However, the pressure of human activities put its ecological integrity at risk, the oldest environmental impact being mining activity recorded since Roman times, about 3500 years ago, reaching its maximum intensity in the 20th century, contributing heavy metals to the lagoon sediments for almost 30 centuries. This work reviews the spatiotemporal evolution of the main heavy metals in this coastal lagoon using data from 272 surface sediment samples obtained during the last 40 years and two deep cores covering the total history of the lagoon (c. 6500 yrs BP), so as their incidence in the lagoon trophic web. The observed patterns in sedimentation, sediment characteristics and heavy metal content respond to the complex interaction, sometimes synergistic and sometimes opposing, between climatic conditions, biological production and human activities, with mining being mainly responsible for Pb, Zn and Cd inputs and port activities for Cu. High Fe/Al, Ti/Al and Zr/Al ratios identify periods of mining activity, while periods of arid climatic conditions and deforestation that increase erosion processes in the drainage basin and silt concentration in the lagoon sediments are determined by high Zr/Rb and, to a lesser extent, Zr/Al and Si/Al ratios. After the cessation of direct discharges into the lagoon in the 1950s, the recent evolution of heavy metals concentration and its spatial redistribution would be determined by hydrographic and biogeochemical processes, solubility of different elements, and coastal works in harbours and on beaches. The bioconcentration factor decreases along the trophic levels of the food web, suggesting that the lagoon ecosystem provides an important service by retaining heavy metals in the sediment, largely preventing their bioavailability, but actions involving resuspension or changes in sediment conditions would pose a risk to organisms.

On the Leptocytheridae Ostracods of the Long-Lived Lake Ohrid: A Reappraisal of their Taxonomic Assignment and Biogeographic Origin.

Leptocythere karamani Klie, one of few non-marine species of the family Leptocytheridae (Ostracoda), is redescribed from specimens recently collected from the long-lived Lake Ohrid on the Albanian-Macedonian border. Detailed morphologies of valves and limbs of this species were compared with those of other Ohrid-Prespa leptocytherids, of some recent marine representatives of the genera Leptocythere Sars and Callistocythere Ruggieri from the Mediterranean, Irish and Baltic seas as well as with that of fossil non-marine species from the Miocene palaeo-Lake Pannon belonging to the genera Amnicythere Devoto and Euxinocythere Stancheva. Comparison with other species of Leptocytheridae inhabiting fresh to brackish waters of the Black-Azov, Caspian and Aral seas were also carried out using descriptions provided in the literature. Based on the comparative morphological studies it is shown that L. karamani and other Ohrid leptocytherids have a number of characters distinguishing them from other members of the genus Leptocythere but demonstrating a relationship with species of the genus Amnicythere. The most reliable of these characters are: a) anterior valve vestibulum from where mostly uni-ramified pore canals start, b) the entomodont hinge type with a strong anterior anti-slip tooth, a smooth posterior anti-slip bar on the left valve, and c) the hemipenis with underdeveloped lateral lobe and reduced clasping organ. From this strong evidence, the Ohrid leptocytherid species are allocated to the genus Amnicythere. Finally, a biogeographic scenario on the origin of the Ohrid leptocytherids is proposed which matches the "Lake Pannon derivate hypothesis". Close relationship of the Ohrid Amnicythere species with the non-marine leptocytherid taxa from the Neogene lakes of Central and Eastern Europe and with extant taxa from the Black and Caspian seas may indicate that the Ohrid Amnicythere derived from Lake Pannon species which were able to colonise lakes in Southern Europe through a stepping-stone process and subsequently to adapt to freshwater environment.