Spatial and Temporal Dynamics of Bentho-Demersal Communities From Bottom Trawl Across the Moroccan Mediterranean Coast in Relation to Environmental Conditions: Implications for Fisheries Management.

Abstract

Understanding the temporal and spatial patterns, as well as habitat preferences, of marine communities is crucial for interpreting ecosystem functioning and effectively protecting marine organisms' resources. In this paper, we investigated the changes in marine communities in the Moroccan Mediterranean (20-620 m depth) over both space and time. Using data from trawl scientific surveys conducted by the National Fisheries Research Institute from 2018 to 2021, we conducted a quantitative analysis to (1) assess the seasonal spatial patterns of bentho-demersal communities, including both economically important species and those not directly targeted by fisheries, and (2) explore the interactions between these communities and environmental factors to gain deeper insights into the dynamics of communities structure. We selected several environmental characterizations including depth, sea surface temperature, bottom temperature, salinity, chlorophyll-a, dissolved oxygen, pH, and bottom seabed nature. Depth was the predominant factor responsible for most of the variation observed in both ecological parameters and the composition of bentho-demersal species. The study largely confirms that bentho-demersal communities along the Moroccan Mediterranean coast respond to their environment, displaying a structural pattern shaped by an offshore to inshore environmental gradient, and exhibiting low seasonal variations. These results have significant implications for fisheries management, offering crucial insights into the parameters influencing the distribution of bentho-demersal communities. This is particularly relevant for mixed-species fisheries, just like those operating in the Moroccan Mediterranean trawl fishery.