Sustained deterioration of marine ecosystems in southern Spain

Recent research focused on the Gulf of Cádiz and the Alborán Sea has exposed the connections between human pressures, biodiversity loss, the provision of ecosystem services and the conservation and management strategies implemented in marine ecosystems. The results are alarming: Biodiversity in both marine areas has been in constant decline for the past three decades.

This study is part of the EME-Mar project, with the participation of biologist Paloma Alcorlo from the Biodiversity and Global Change Research Center (CIBC), attached to the Autonomous University of Madrid (UAM), in collaboration with a team of scientists from the UAM, the University of Murcia and the Rey Juan Carlos University, all of these institutions in Spain.

“Our starting hypothesis was that anthropogenic pressures intensify the loss of marine biodiversity and reduce the corresponding ecosystem services,” explains Alcorlo. “To do this, we used an integrated modeling approach and selected 60 indicators at the regional, national and international levels that provided long-term information for the period between 1985 and 2019”.

“Our results -adds the researcher- showed a decrease in marine biodiversity and its ecosystem services, despite the growing number of responses provided by society that are insufficient and/or need more time to take effect”.

The oceans, which cover more than 70% of the Earth’s surface, provide a variety of “ecosystem services.” These are the benefits derived from the very functioning of the marine ecosystem, for example: the provision of food and the generation of oxygen, as well as the crucial role of these in regulating the climate by absorbing carbon dioxide and influencing weather patterns.

The importance of these services to human populations has grown exponentially over the past century. However, technological and social progress has allowed the exploitation of coastal and marine ecosystems, highlighting the prevailing need for strategies to counteract this trend.

The EME-Mar project studies the interactions between biodiversity, supply of marine ecosystem services, anthropogenic pressures and management strategies for marine areas. (Photo: INWET / UAM / CIBC)

Conservation policies: a pending challenge

In 2018, the global fishing industry reached a historic milestone by catching 96.4 million tonnes of marine fish, molluscs, crustaceans and other invertebrates, with at least 34.2% of global stocks assessed to be overexploited. This situation is exacerbated in the Mediterranean Sea: according to the European Commission’s Technical-Economic Scientific Committee for Fisheries (STECF), 83% of the assessed fish stocks are overexploited.

The growing scientific and social awareness of the precariousness of the oceans and marine biodiversity has prompted the creation of marine protected areas (MPAs) in all the world’s oceans. These areas are characterized by having established protection objectives and limiting permitted fishing activities, focusing efforts on conservation. However, despite the constant increase in conservation regulations and policies, efforts to protect marine biodiversity still fall short of what is necessary.

“We would hope that the management policies implemented could mitigate the intensity of the anthropogenic pressures that trigger the loss of biodiversity in the Gulf of Cádiz and the Alborán Sea. However, according to our findings, they have not had the desired protective effect of guaranteeing a long-term recovery of stocks and sustainable fishing,” says Alcorlo.

Take an ecosystem approach

The study suggests that current conservation strategies may be insufficient or ineffective, or that there are other factors at play in the decline. Among the possible reasons that explain this inability to mitigate the loss of biodiversity are inefficient policies due to lack of knowledge or political interest, and the inappropriate design and size of marine protected areas.

The work points out other stress factors that contribute to the loss of biodiversity and that are not officially quantified, such as extraction by sport fishing vessels, black market fish trade, subsistence fishing, non-artisanal fishing recorded and poaching.

Lastly, the researchers of the EME-Mar project emphasize that “managing fisheries in a sustainable manner that allows for the production of high-quality food, as well as guaranteeing income and livelihoods for societies that depend on fishing, while Once the negative effects on biodiversity are minimized, they are unavoidable challenges”.

“It is essential to adopt an ecosystem approach that connects human needs and impacts with the state of biodiversity and its conservation, allowing an integrated decision-making process when managing coastal and marine ecosystems,” conclude the study authors. .

The study is entitled “Unravelling Complex Interaction among Coastal Management and Marine Biodiversity: A Case Study in Southern Spain”. And it has been published in the academic journal Sustainability. (Source: UAM)