Environmental status assessment of Mediterranean Sea finds notable differences between ecoregions

The researchers say that protected areas enhanced fish populations and no-trawl zones improved overall ecological status. They argue that more work is needed to gather sufficient data for assessments and to develop indicators that accommodate differences between sites.

Protecting marine biodiversity is a global concern specifically covered by the UN’s Sustainable Development Goal 14 (Life Below Water) and addressed in the EU through various instruments, primarily the Marine Strategy Framework Directive. The main goal of the directive is to achieve ‘good environmental status’, based on 11 descriptors, in marine ecosystems across Member States. It establishes the model of marine protected areas as a key tool for achieving this, although 'good environmental status’ should be achieved in non-protected areas as well. This study¹ aimed to investigate the environmental status across the Mediterranean Sea with reference to protected areas and a range of ecosystem components.

The study assessed 26 marine protected areas alongside corresponding non-protected control areas (more than 20 kilometres away). It also included a non-trawl area alongside two control areas that permit trawling. The researchers gathered data for each site from scientific literature published between 2015 and 2019, comprising 1 249 separate records. They focused on seven ecosystem components – including seagrass (Posidonia oceanica), macroalgae (seaweeds), fish and sea urchins – for which sufficient information was available on their spatial occurrence, current status, trends and ecological interactions. They used one or more indicators, such as abundance or biomass, to evaluate each ecosystem component. They then analysed the data using the Nested Environmental status Assessment Tool, developed by the EU DEVelopment Of innovative Tools for understanding marine biodiversity and assessing good Environmental Status (DEVOTES) project.

According to the researchers the assessment for the whole Mediterranean Sea returned a ‘moderate’ environmental status. However, there were notable differences between ecoregions, they say, with the Western Mediterranean achieving ‘good’ status, the Adriatic and Aegean seas at ‘moderate’ status and the Ionian ‘poor’. Protected areas in the Western Mediterranean mostly achieved ‘good’ or ‘high’ status, they report. The no-trawl area was very effective, they say, with ‘high’ environmental status, while the trawled control areas were ‘poor’ or ‘bad’.

The overall status levels for seagrass and sea urchins were ‘high’ and ‘good’ respectively, according to the researchers, contributing significantly to the achievement of ‘moderate’ status across the Mediterranean. They report that macroalgae were mostly low but notably higher in protected areas in the Western Mediterranean. Algal forests formed by canopy and erect algae appear to be the most challenging components for conservation, as these were overall found in ‘bad’ condition, both in protected and non-protected areas at the basin scale. The researchers suggest that MPAs alone cannot assist the recovery of canopy algae. They recommend additional conservation actions such as improvement of water quality, control of indigenous and invasive herbivores, and implementation of restoration actions to prevent the loss of canopy algae.

Fish abundance was greater in protected areas than non-protected ones in all regions, they say, particularly in the Western Mediterranean and the Aegean.

The researchers draw attention to the effectiveness of the trawling ban and suggest that this approach could be applied more widely. They say that although protected areas are effective at enhancing fish populations, this effect does not appear to extend substantially beyond their boundaries to the control areas.

The researchers argue that a complex set of conditions results in a highly context-dependent status of different areas – due to varying ecological relationships and management techniques. They observe that protected areas in the Adriatic have not achieved ‘good’ environmental status despite evidence that conservation actions have been effective. They suggest that this is because certain environmental features and long-term impacts make the threshold levels of key indicators unattainable in some sites. They argue that setting appropriate ecological targets is a substantial challenge, especially alongside ongoing environmental disturbance from factors such as climate change and invasive species expansion.

The researchers suggest that an increase in systematic, long-term monitoring is needed to provide adequate data for thorough assessments of ecosystem health. They note that many of the source studies are based on samples from very small areas and they highlight the need for larger-scale surveys to more accurately represent the areas being considered. They also recommend further development of complementary protection measures, such as Natura 2000 sites.  They propose that future work should support the development of flexible environmental indicators that can be adapted to site-specific conditions and situations.

Footnotes:

1. Part of the EU Advancing marine conservation in the European and contiguous seas

(MarCons COST) action and supported by the EU MEDREGION and Towards the establishment of Marine Protected Area Networks in the Eastern Mediterranean (PROTOMEDEA) projects.

Source:

Fraschetti, S., Fabbrizzi, E., Tamburello, L., Uyarra, M. C., Micheli, F., Sala, E., Pipitone, C., Badalamenti, F., Bevilacqua, S., Boada, J., Cebrian, E., Ceccherelli, G., Chiantore, M., D'Anna, G., Di Franco, A., Farina, S., Giakoumi, S., Gissi, E., Guala, I., Guidetti, P., Katsanevakis, S., Manea, E., Montefalcone, M., Sini, M., Asnaghi, V., Calò, A., Di Lorenzo, M., Garrabou, J., Musco, L., Oprandi, A., Rilov, G., and Borja, A. (2022) An integrated assessment of the Good Environmental Status of Mediterranean Marine Protected Areas. Journal of Environmental Management 305: 114370. Available from: https://doi.org/10.1016/j.jenvman.2021.114370

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“Science for Environment Policy”: European Commission DG Environment News Alert Service, edited by the Science Communication Unit, The University of the West of England, Bristol.

Notes on content:

The contents and views included in Science for Environment Policy are based on independent, peer reviewed research and do not necessarily reflect the position of the European Commission. Please note that this article is a summary of only one study. Other studies may come to other conclusions.