No abstract

No abstract

No abstract

In this work we study the response of phytoplankton and potentially harmful species to river inflows in a coastal area of eastern Mediterranean, within the context of environmental status assessment suggested by the European Commission’s Water Framework Directive (WFD, 2000/60/EC) and Marine Strategy Framework Directive (MSFD, 2008/56/EC). The spatio-temporal distribution of phytoplankton communities and biomass (as chlorophyll a), potentially harmful species, nutrient levels, dissolved oxygen, salinity and temperature were studied. A marginal good to moderate physicochemical status was assigned in the delta of Spercheios river that outflows in Maliakos Gulf. Silicates and nitrates were indicated as proxies of freshwater influence in Maliakos Gulf, whereas ammonium, nitrites and phosphates as proxies of pollutants from non-point sources. Phytoplankton biomass and abundances reached high levels throughout Maliakos Gulf inter-seasonally. High silicates favored the dominance of Diatoms. The potentially harmful species were blooming frequently, with higher levels in the estuary, and they were associated with low salinity, showing the riverine influence on them. Pseudo-nitzschia was the most frequent potentially harmful genus with an interesting strong linkage with low silicates and nitrates. Maliakos Gulf demonstrated an overall mesotrophic condition and failed to achieve good ecological status.

No abstract

At present there is no consistent approach for the definition of Good Environmental Status (GES) and targets in the Mediterranean Sea, especially for Biodiversity Descriptors, according to the Article 12 of the Marine Strategy Framework Directive (MSFD). The use of plankton indicators in the Mediterranean Sea refers mostly to pelagic habitats in coastal waters and to case studies connected with environmental pressures, e.g. in the Adriatic, Aegean etc. The aim of this review is to study the existing biodiversity indicators for different plankton groups in order to compare GES definitions for the Biodiversity Descriptor and identify the relevant gaps and priority needs to improve coherence for the MSFD implementation across the Mediterranean. For these purposes, we focus on plankton indicators for phytoplankton, zooplankton and prokaryotes. Regional conventions (OSPAR, HELCOM, Barcelona and Bucharest Conventions) have long considered phytoplankton as a key element for integrated assessment systems. Phytoplankton biomass, community composition, abundance, frequency and intensity of blooms are used for such assessment purposes. Chlorophyll a still remains the most widely used indicator mostly thanks to its time saving, cost-effective and reproducible analytical methods that provide easily comparable datasets. Despite some integrated indices proposed for phytoplankton in the literature at the Mediterranean level, a number of constrains still prevent their wide use. Regarding zooplankton communities, commonly used indicators have a taxonomic base while recently size structure and biomass can provide a valuable index of zooplankton population dynamics and ecosystem production. Jellyfish blooms' occurrence and frequency are also considered important zooplankton Highlights ► Low coherence for GES definitions in Mediterranean plankton communities was found. ► Phytoplankton is a key element for assessment systems of MSFD and Regional Conventions. ► GES targets are based only on Chlorophyll a thresholds in the Mediterranean so far. ► Quantitative GES targets for zooplankton in Mediterranean exist only in Slovenia. ► Gaps mostly focus on lack of thresholds and baselines for many biodiversity indicators.

No abstract

The loss of Mediterranean macroalgal populations dominated by Cystoseira sensu lato is driven by a multitude of pressures. In the eastern Mediterranean Sea, climate change and the establishment of Lessepsian herbivore species have further intensified the ongoing decline of these canopy-forming algae. Knowledge of the reproductive phenology, embryology and growth of Cystoseira species is the first step towards successful reforestation measures. Gongolaria montagnei is one of the most common canopy-forming algal species with a wide horizontal and vertical distribution along the Greek coasts. Mature receptacles were collected from Saronikos Gulf (Aegean Sea), and germlings were cultured in mesocosms for 34 days, reaching up to 1.30 mm in length. Divisions and early developmental stages of G. montagnei are described and possible implications for future restoration efforts are discussed. A new approach to growth rate modeling, based on surface measurements of embryos and germlings is presented.