Ecosystem exploitation and trophodynamic indicators: A comparison between the Northern Adriatic Sea and Southern New England     

Fabio Pranovi  Jason S. Link   《Progress in Oceanography》2009,81(1-4):149

In an ecosystem-based resource management context, it is crucial to assess the relationships between community structure and ecosystem function and how those relationships change with resource extraction. To elucidate how changes in resource use can affect community structure and ecosystem function, we executed a comparative analysis of two different ecosystems subjected to notable fishing pressure. We contrasted the Northern Adriatic Sea (NAS) and Southern New England (SNE) ecosystems by examining outputs from comparable steady-state models. Both ecosystems have relatively high fishing pressure and a high biomass of benthic invertebrates. The basic structure of the food webs shows differences both in the number and definition of the functional groups, as described in the models. Fisheries, on the contrary, show similarities both in terms of catches and discards. Almost all statistics summarizing the structure and flows showed values three times higher in the SNE than in the NAS ecosystem, but despite this difference the two ecosystems exhibited similar, overall properties. Biomass ratios and the Mixed Trophic Impact (MTI) analysis showed that both ecosystems are dominated by the benthic compartment. Removing the biomass effect, however, shows a clear top-down effect, with a high rank achieved by fishing activities. In general terms, the low mean trophic level of catches and the high primary production required (PPR) values result in a high overexploitation level of the ecosystem, as highlighted by the L index. We conclude by exploring how comparative studies will continue to be valuable as ecosystem-based management is further implemented.  相似文献   

The operational sex ratio of the sea urchin Paracentrotus lividus populations: the case of the Mediterranean marine protected area of Ustica Island (Tyrrhenian Sea, Italy)     

Paola Gianguzza  Fabio Badalamenti  Fabrizio Gianguzza  Chiara Bonaviri  & Silvano Riggio 《Marine Ecology》2009,30(1):125-132

We investigated, with a series of field and laboratory observations, the possible effect of the starfish Marthasteria glacialis predation on the operational sex ratio (OSR), i.e. the number of sexually mature males divided by the total number of sexually mature adults of both sexes at any one time, of the edible sea urchin Paracentrotus lividus . The OSR was estimated three times during the sea urchin summer spawning period (July 2004, June 2005 and July 2006) on barren substrates of Ustica Island Marine Protected Area (Southern Tyrrhenian Sea, Italy). Four sites were selected: two characterized by high M. glacialis density (take zone C) and two controls with low starfish density (no-take zone A). Mature sea urchins were independently collected by SCUBA diving and sexed. The adult sex ratio was skewed towards males at high M. glacialis density sites, whereas it was balanced (1:1) at predator low-density sites. Results of sex-selective feeding experiments in the laboratory showed that females of P. lividus were more vulnerable to M. glacialis predation. These outcomes underline the possible importance of M. glacialis in regulating the OSR of P. lividus populations.  相似文献   

Steeper biomass spectra of demersal fish communities after trawler exclusion in Sicily     

Sweeting  Christopher J.; Badalamenti  Fabio; D'Anna  Giovanni; Pipitone  Carlo; Polunin  N. V. C. 《ICES Journal of Marine Science》2009,66(1):195-202

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