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X-Ray Mag #62 - Sep 2014
X-Ray Mag #62 - Sep 2014
X-Ray Mag #62 - Sep 2014
X-Ray Mag #62 - Sep 2014
X-Ray Mag #62 - Sep 2014
X-Ray Mag #62 - Sep 2014
X-Ray Mag #62 - Sep 2014
X-Ray Mag #62 - Sep 2014
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Mediterranean best protected by no-take marine reserves

A study by international scientists suggests that the best way for marine life to recover is by marine reserves.
  Photo: Parent Géry / Wikimedia Commons
Dusky grouper (Epinephelus marginatus)
Intense exploitation over millennia has depleted Mediterranean species from the large to the small, including the Mediterranean monk seal, sea turtles, bluefin tuna, groupers, red coral, lobsters and limpets. Habitat destruction, pollution, introduced species and climate change have also taken a toll on Mediterranean species and ecosystems.
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The study which conducted surveys at multiple locations, from Turkey to Morocco, provides the first benchmark of the structure of the Mediterranean rocky nearshore marine life. A major insight is that, at the Mediterranean scale, partially protected MPAs (which allow some fishing) are not effective in restoring fish populations – as opposed to well enforced no-take marine reserves, which are effective.

Historical ecosystems
Marine conservation should not be about protecting at any cost, but to keep a sustainable environment based on its natural environment. This raises the question; what would a ‘healthy’ Mediterranean rocky bottom look like? There are no pristine sites (i.e. undisturbed by humans, with historical ecosystem structure and carrying capacity) left in the Mediterranean that allows us to set a baseline against which to compare the health of current ecosystems. Research made on pristine historically unfished sites in the central Pacific, show intact complex reef ecosystems harbor large biomass of fishes with inverted biomass pyramids and high coral cover.

Fishing pressure has been a major stressor on Mediterranean reef systems. Thus, in the Mediterranean, we would expect total fish biomass to be also the single most important indicator of the health of fish populations, with biomass increasing with decreased fishing pressure, as Mediterranean no-take marine reserves demonstrate. Therefore, according to the study marine reserves are the best for recovery of fish towards a pristine state, possibly including cascading effects leading to a wider recovery of the protected ecosystems. However, the scientists still expect these current baselines to be far from historical intact ecosystems, which include all apex predators such as sharks and monk seals.

Enforcement vital
An important result of the study is that MPAs where fishing is allowed and weakly enforced no-take marine reserves had fish biomass comparable to unprotected sites. The worst performing MPA was Morocco’s Al-Hoceima, which is a ‘paper park’ with virtually no management and enforcement. While apex predators, which are an important component of the fish population, reach a maximum of 49% of total fish biomass at the Medes Islands Marine Reserve, Spain. This is similar to the Papahanaumokuakea Marine National Monument in the NW Hawaiian Islands, USA and approaching the inverted biomass pyramid found at unfished reefs in the central Pacific. Moreover, the biomass of apex predators such as the dusky grouper (Epinephelus marginatus) continues to increase at the Medes Island Marine Reserve after 27 years of protection. These results suggest that well enforced Mediterranean marine reserves are recovering similarly to reserves elsewhere that moved from a degraded state with a low fish population to populations similar to unfished sites.

Climate change
In addition to the direct and indirect impacts of overexploitation, there have been other major impacts to Mediterranean nearshore reefs. Historically, land use changes in the Mediterranean region had accompanying changes in nutrients and sedimentation, and a major loss of coastal habitats. The
Mediterranean is also increasingly affected by climate change. Seawater temperatures are steadily increasing, extreme climatic events and related disease outbreaks are becoming more frequent, faunas are shifting, and invasive species are spreading.

Source:
Sala E, Ballesteros E, Dendrinos P, Di Franco A, Ferretti F, et al. (2012) The Structure of Mediterranean Rocky Reef Ecosystems across Environmental and Human Gradients, and Conservation Implications. PLoS ONE 7(2): e32742. doi:10.1371/journal.pone.0032742

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