Alien turf: Overfishing, overgrazing and invader domination in south-eastern Levant reef ecosystems

Gil Rilov, Ohad Peleg, Erez Yeruham, Tal Garval, Ania Vichik, Ofrat Raveh

Research output: Contribution to journalArticlepeer-review

Abstract

Coastal reefs are highly diverse marine ecosystems that in many regions suffer today from growing pressures by human activities. Among the most highly-stressed are those found in the Levantine basin (south-eastern Mediterranean Sea). The Levant represents the trailing-edge of distribution of native species where they are exposed to the most extreme temperature and salinity conditions, and the region is also fast-warming and exposed to a great many alien species and strong fishing pressure. In this study, the ecological state of reefs in the south-eastern Levant was assessed quantitatively (including inside a small marine reserve) using current, extensive, survey data with reference to anecdotal historical information on their more pristine past. The results of very extensive subtidal community surveys that were conducted in north Israel indicate that reefs in this area are currently dominated by turf-forming algae and aliens, and sustain low numbers of top predators. Specifically, it was found that on these Levant reefs: (1) commercial species represent a very small part of the fish assemblage (except inside the reserve); (2) alien species constitute a considerable portion (23–44%) of the fish assemblage (including in the reserve) and 95–99% of epi-benthic molluscs, including inside the marine reserve; and (3) turf barrens are the dominant substrate cover, while cover of native brown algae canopy is limited to small patches occurring only during winter and spring. These findings suggest that the Levant reefs have been highly transformed by overfishing and alien invasions, and probably also climate change, and that even well managed marine reserves had little effect on alien species presence. From a biogeographic-conservation perspective, as both warming and bioinvasions continue in the Mediterranean, it is expected that this degraded reef state will gradually advance westward. Alleviating fishing pressure with marine reserves might make the reefs more resilient to these regional pressures, but alien invaders will remain a dominant feature in the system. Therefore, a more realistic conservation target might be the preservation or restoration of ecosystem functions rather than the original native biodiversity.

Original languageEnglish
Pages (from-to)351-369
Number of pages19
JournalAquatic Conservation: Marine and Freshwater Ecosystems
Volume28
Issue number2
DOIs
StatePublished - Apr 2018

Bibliographical note

Funding Information:
Israel Ports Company; Goldman Philanthropic Partnerships; European Commission, Grant/ Award Number: 249147; Israel Science Foundation, Grant/Award Number: 1217/10; Marie Curie Reintegration Programme under the European Union's Seventh Framework, Grant/ Award Number: 249147

Funding Information:
We thank IOLR's Marine Community Ecology Lab past research assistants (A. Konstantinovsky, N. Bartov, E. Israeli, Y. Hyams, U. Arkin, A. Barash, M. Grossowicz, U. Zacharia, O. Almog, O. Frid, O. Abramson) for their extensive efforts in both field (40–50 dives per season) and lab work. We thank the marine crew of IOLR for their help in the field (especially E. Hagai). Our study in the marine reserve was greatly supported by EcoOcean that provided their research boat under reduced cost, as well as the Israel Parks and Nature Authority that helped with the logistics and with post‐survey site mapping. Several people helped with taxonomic identification including A. Israel with macroalgae, H. Mienis with mollusca, S. Shefer with sponges and E. Mizrahi with worms. The Rinkevich lab at IOLR did the DNA barcoding and identified several of the live rock specimens for the Haifa surveys. This work was supported mainly by the Goldman Foundation, the Israel Port Authority, and also partly by grants from the Marie Curie Reintegration Programme under the European Union's Seventh Framework, grant number 249147 (to G.R.), and the Israel Science Foundation, grant number 1217/10 (to G.R.).

Publisher Copyright:
Copyright © 2017 John Wiley & Sons, Ltd.

Keywords

  • alien species
  • biodiversity
  • climate change
  • coastal
  • fishing
  • marine protected areas

ASJC Scopus subject areas

  • Aquatic Science
  • Ecology
  • Nature and Landscape Conservation

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