Using fish assemblages to assess the ecological effects of marine protection on rocky habitats in a Portuguese natural park

Abstract

Intensive and regular fishing occurs in the marine area of the natural park “Parque Natural do Sudoeste Alentejano e Costa Vicentina” (PNSACV; SW coast of continental Portugal). In 2011, this area became a marine park with different protection levels (total, partial, and complementary). We assessed in 2011 and 2012 if partial protection (PP) in Marine Protected Areas (MPAs) changed the taxa richness, abundance, size, and community composition of cryptic and non-cryptic fishes. We also determined if these effects were observed outside PP areas in adjacent control areas. Underwater visual censuses (UVC) of cryptic and non-cryptic fish species were conducted in rocky subtidal habitats (~10 m deep) with band transects (25 x 2 m and 25 x 4 m, respectively) to determine abundance and size classes. The northern half of the PNSACV was sampled at a scale of tens (site— two sites per area; 4–6 transects per site) and hundreds (area) of meters. Two PP and six control areas were sampled. The homogeneity and abundance of bottom habitat types were assessed at each site. Effects of protection were not detected in the community structure or univariate analyses (i.e., taxa richness and total abundance) of non-cryptic and cryptic fishes. The early phase of the MPAs may have driven the lack of significant protection effects. Replication in time within a monitoring program is recommended to assess these conservation measures’ ecological effects.