Remarkable size-spectra stability in a marine system undergoing massive invasion

Area of Science:

• Marine biology
• Ecology
• Fisheries science

Background:

• The Mediterranean Sea is a biodiversity hotspot experiencing significant biological invasions.
• Non-indigenous species are suspected drivers of community structure changes in invaded ecosystems.
• Size spectra are reliable indicators of food web structure and community dynamics.

Purpose of the Study:

• To investigate the impact of Red Sea fish invasions on indigenous Mediterranean species communities.
• To utilize size spectra analysis as a novel method for assessing biological invasion effects.
• To compare the community size spectra of indigenous and non-indigenous species over a 20-year period.

Main Methods:

• Analysis of 20 years of trawl catch data from Israel's Mediterranean coastline.
• Estimation and comparison of community size spectra for indigenous and non-indigenous fish species.
• Assessment of changes in relative biomass and size distribution of both species groups.

Main Results:

• Non-indigenous species biomass increased significantly over the 20-year study period.
• The size spectra of non-indigenous species converged with those of indigenous species, particularly for small and large size classes.
• The size spectrum of indigenous species remained stable, showing no significant changes throughout the invasion period.

Conclusions:

• Despite increased biomass of non-indigenous species, indigenous species community structure in the Mediterranean appears resilient to these invasions.
• The convergence of size spectra suggests similar ecological roles or sensitivities (e.g., to fishing) between indigenous and invasive species.
• The study highlights the utility of size spectra in evaluating the ecological impact of biological invasions on marine communities.