Argyro Zenetos

A Sea Change — Exotics in the Eastern Mediterranean Sea

The eastern Mediterranean is susceptible to biological invasions because of its placement between the Atlantic, Pontic and Erythrean regions, busy maritime traffic, and lagoons and bays that are crowded with fish and shellfish farms. However, the greatest influx of invaders resulted from the opening of the Suez Canal in 1869, which allowed entry of Indo-Pacific and Erythrean biota. Exotic macrophytes, invertebrates and fish are found in most coastal habitats in the eastern Mediterranean. Some invaders have outcompeted or replaced native species locally, some are considered pests or cause nuisance, whereas other invaders are of commercial value. However, at variance with other invaded seas, the invasion into the eastern Mediterranean has increased the region’s biodiversity. The rate of marine biotic invasions has increased in recent decades; collectively they have significant ecological and economic impacts in the eastern Mediterranean. Some Erythrean invaders have already spread as far west as Malta and Sicily, and if global warming was to affect the Mediterranean sea-water temperature, then tropical invasive species would gain a distinct advantage over the native fauna.

Changes in benthic community structure along an environmental pollution gradient

Seasonal sampling of the benthic fauna in the Saronikos Gulf was undertaken during 1989 along three transects with increasing distance from the Great Collector outfall. The faunistic composition, descriptive measures and Cluster and Abundance/Biomass Comparison analyses were all used to assess the different degrees of pollution around the study area. The results of the above univariate and multivariate analyses indicate that the area can be divided into three zones according to the degree of pollution affecting the communities.

Ecoregion-Based Conservation Planning in the Mediterranean: Dealing with Large-Scale Heterogeneity

Spatial priorities for the conservation of three key Mediterranean habitats, i.e. seagrass Posidonia oceanica meadows, coralligenous formations, and marine caves, were determined through a systematic planning approach. Available information on the distribution of these habitats across the entire Mediterranean Sea was compiled to produce basin-scale distribution maps. Conservation targets for each habitat type were set according to European Union guidelines. Surrogates were used to estimate the spatial variation of opportunity cost for commercial, non-commercial fishing, and aquaculture. Marxan conservation planning software was used to evaluate the comparative utility of two planning scenarios: (a) a whole-basin scenario, referring to selection of priority areas across the whole Mediterranean Sea, and (b) an ecoregional scenario, in which priority areas were selected within eight predefined ecoregions. Although both scenarios required approximately the same total area to be protected in order to achieve conservation targets, the opportunity cost differed between them. The whole-basin scenario yielded a lower opportunity cost, but the Alboran Sea ecoregion was not represented and priority areas were predominantly located in the Ionian, Aegean, and Adriatic Seas. In comparison, the ecoregional scenario resulted in a higher representation of ecoregions and a more even distribution of priority areas, albeit with a higher opportunity cost. We suggest that planning at the ecoregional level ensures better representativeness of the selected conservation features and adequate protection of species, functional, and genetic diversity across the basin. While there are several initiatives that identify priority areas in the Mediterranean Sea, our approach is novel as it combines three issues: (a) it is based on the distribution of habitats and not species, which was rarely the case in previous efforts, (b) it considers spatial variability of cost throughout this socioeconomically heterogeneous basin, and (c) it adopts ecoregions as the most appropriate level for large-scale planning.

Invading the Mediterranean Sea: biodiversity patterns shaped by human activities

Human activities, such as shipping, aquaculture, and the opening of the Suez Canal, have led to the introduction of nearly 1,000 alien species into the Mediterranean Sea. We investigated how human activities, by providing pathways for the introduction of alien species, may shape the biodiversity patterns in the Mediterranean Sea. Richness of Red Sea species introduced through the Suez Canal (Lessepsian species) is very high along the eastern Mediterranean coastline, reaching a maximum of 129 species per 100 km2, and declines towards the north and west. The distribution of species introduced by shipping is strikingly different, with several hotspot areas occurring throughout the Mediterranean basin. Two main hotspots for aquaculture-introduced species are observed (the Thau and Venice lagoons). Certain taxonomic groups were mostly introduced through specific pathways – fish through the Suez Canal, macrophytes by aquaculture, and invertebrates through the Suez Canal and by shipping. Hence, the local taxonomic identity of the alien species was greatly dependent on the dominant maritime activities/interventions and the related pathways of introduction. The composition of alien species differs among Mediterranean ecoregions; such differences are greater for Lessepsian and aquaculture-introduced species. The spatial pattern of native species biodiversity differs from that of alien species: the overall richness of native species declines from the north-western to the south-eastern regions, while the opposite trend is observed for alien species. The biodiversity of the Mediterranean Sea is changing, and further research is needed to better understand how the new biodiversity patterns shaped by human activities will affect the Mediterranean food webs, ecosystem functioning, and the provision of ecosystem services.

Additions to the marine alien fauna of Greek waters (2007 update)

The list of marine alien fauna in Greek waters is updated taking into account new findings (published and unpublished data). According to the present work, the number of species increases from 102 to 110. Of the eight new records, five are zoobenthic species, two zooplanktonic and another one a teleost fish. Moreover, records referring to the expansion range of aliens from an established stand to new areas are also presented, pointing out the species that could be considered as possible invaders to local communities.

Distribution of Molluscs and Polychaetes in Coastal Lagoons in Greece

Abstract Hydrochemical (salinity, dissolved oxygen) and sedimentological parameters were investigated in the Messologhi lagoonal area of Greece in July 1981 and compared to the distribution of molluscs and polychaetes by means of the Spearman rank correlation. Dissolved oxygen in bottom waters showed the most obvious correlation with the distribution of species. The grouping of sampling stations based upon their faunal affinities displays the zonal organization of lagoonal populations which may be accounted for in terms of extent of isolation from the open sea, as in other Mediterranean lagoonal systems.

The Impact of Dumping Coarse Metalliferous Waste on the Benthos in Evoikos Gulf, Greece

Dumping of coarse metalliferous wastes, at about 75 m depth had mostly indirect effects on the benthic fauna, through changing the particle size composition of the sediment. Coarse polluted sediments had greater number of species and individuals and higher diversity than fine sediments but lower than clean sediments of similar partic!e size. The stability of the community decreased as indicated by the substitution of its characteristic species by others with wide ecological requirements.

European Marine Biodiversity Monitoring Networks: Strengths, Weaknesses, Opportunities and Threats

By 2020, European Union Member States should achieve Good Environmental Status (GES) for eleven environmental quality descriptors for their marine waters to fulfill the Marine Strategy Framework Directive (MSFD). By the end of 2015, in coordination with the Regional Seas Conventions, each EU Member States was required to develop a marine strategy for their waters, together with other countries within the same marine region or sub-region. Coherent monitoring programs, submitted in 2014, form a key component of this strategy, which then aimed to lead to a Program of Measures (submitted in 2015). The European DEVOTES FP7 project has produced and interrogated a catalogue of EU marine monitoring related to MSFD descriptors 1 (biological diversity), 2 (non-indigenous species), 4 (food webs) and 6 (seafloor integrity). Here we detail the monitoring activity at the regional and sub-regional level for these descriptors, as well as for 11 biodiversity components, 22 habitats and the 37 anthropogenic pressures addressed. The metadata collated for existing European monitoring networks were subject to a SWOT (strengths, weaknesses, opportunities and threats) analysis. This interrogation has indicated case studies to address the following questions: a) what are the types of monitoring currently in place?; b) who does what and how?; c) is the monitoring fit-for-purpose for addressing the MSFD requirements?, and d) what are the impediments to better monitoring (e.g. costs, shared responsibilities between countries, overlaps, co-ordination)? We recommend the future means, to overcome the identified impediments and develop more robust monitoring strategies and as such the results are especially relevant to implementing coordinated monitoring networks throughout Europe, for marine policy makers, government agencies and regulatory bodies. It is emphasized that while many of the recommendations given here require better, more extensive and perhaps more costly monitoring, this is required to avoid any legal challenges to the assessments or to bodies and industries accused of causing a deterioration in marine quality. More importantly the monitoring is required to demonstrate the efficacy of management measures employed. Furthermore, given the similarity in marine management approaches in other developed systems, we consider that the recommendations are also of relevance to other regimes worldwide.

Update of the marine Bivalvia Mollusca checklist in Greek waters

Species of marine bivalve molluscs identified in the last nine years in the Greek waters have been used to update the checklist published in 1996 (Fauna Graeciae VII) by inserting necessary changes and adding new records. The updated version includes 13 new species among which three are exotics (non-Mediterranean species), five rare, two new deep sea and one previously considered a fossil species. Also, as a result of new resources, the distributions of pre-existing native molluscs have been updated to include new habitat areas. The nomenclature is also up to date based on the CLEMAM Database. Thus five species are now excluded either because they are junior synonyms of pre-existing valid species (2) or because of old spurious records (3 species). Additions and corrections of the 1996 checklist have resulted in a total of 308 bivalves in Greek waters.

Evaluation of Online Information Sources on Alien Species in Europe: The Need of Harmonization and Integration

Europe is severely affected by alien invasions, which impact biodiversity, ecosystem services, economy, and human health. A large number of national, regional, and global online databases provide information on the distribution, pathways of introduction, and impacts of alien species. The sufficiency and efficiency of the current online information systems to assist the European policy on alien species was investigated by a comparative analysis of occurrence data across 43 online databases. Large differences among databases were found which are partially explained by variations in their taxonomical, environmental, and geographical scopes but also by the variable efforts for continuous updates and by inconsistencies on the definition of “alien” or “invasive” species. No single database covered all European environments, countries, and taxonomic groups. In many European countries national databases do not exist, which greatly affects the quality of reported information. To be operational and useful to scientists, managers, and policy makers, online information systems need to be regularly updated through continuous monitoring on a country or regional level. We propose the creation of a network of online interoperable web services through which information in distributed resources can be accessed, aggregated and then used for reporting and further analysis at different geographical and political scales, as an efficient approach to increase the accessibility of information. Harmonization, standardization, conformity on international standards for nomenclature, and agreement on common definitions of alien and invasive species are among the necessary prerequisites.