Exceptionally high but still growing predatory reef fish biomass after 23 years of protection in a Marine Protected Area

PLoS One. 2021 Feb 8;16(2):e0246335. doi: 10.1371/journal.pone.0246335. eCollection 2021.

Abstract

Marine Protected Areas (MPAs) help replenish fish assemblages, though different trophic levels may show diverse recovery patterns. Long-term protection is required to achieve total recovery but poaching events may prevent the achievement of full carrying capacity. Here, we have analysed the effect of long-term protection on the entire reef fish community and the different trophic levels in the Cabo de Palos-Islas Hormigas MPA (SE Spain; SW Mediterranean Sea) in order to assess their recovery patterns after 23 years of protection. We compared the values for carrying capacity obtained with the maximum values achieved at regional scale, and we assessed the effect of a reduction in the surveillance over a few years, during which poaching events increased, on the recovery patterns. We found that, overall, biomass of fishes increased with time while density diminished. In particular, piscivorous and macro-invertivore fish increased while the other trophic groups remained constant or declined, suggesting top-down processes. For the entire study period, those trophic groups were approaching carrying capacity; however, when accounting only for the period in which enforcement was high and constant, they grew exponentially, indicating that full carrying capacity may have not been achieved yet. When compared to other Mediterranean MPAs, the Cabo de Palos-Islas Hormigas MPA showed values for biomass that were disproportionately higher, suggesting that local factors, such as habitat structure and associated oceanographic processes, may be responsible for the dynamics found. Our results help to understand the potential trajectories of fish assemblages over a consolidated MPA and highlight empirically how the reduction of surveillance in a period may change the recovery patterns.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomass*
  • Conservation of Natural Resources* / statistics & numerical data
  • Coral Reefs*
  • Fishes*
  • Mediterranean Sea
  • Population Growth
  • Predatory Behavior

Grants and funding

This work is part of the research projects "Scientific Monitoring of the Cabo de Palos - Islas Hormigas marine reserve (1996-2018)" (Regional Fisheries and Aquaculture Service - Autonomous Community of Murcia, with funds from EU, notably the European Maritime and Fisheries Fund - EMFF), REDEMED (MINECO CGL2013-49039-R) and ABHACO2DE (Fundación Séneca 19516/PI/14). IR is funded by a Spanish MINECO FPI contract. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.