The invasive soft-shell clam Mya arenaria was recorded for the first time in the Tagus estuary, central Portugal. Propagules of the soft-shell clam were probably unintentionally introduced into the Tagus estuary through ballast water. Mya arenaria was observed in muddy sands in the upper intertidal zone. The assemblage in which the softshell clam was observed was composed of typical estuarine species such as the gastropod Hydrobia ulvae, the bivalve Scrobicularia plana and several polychaete species. The population density of Mya arenaria in the finding area was 40 ind m -2 with a fresh biomass of 163.5 g FW m -2 .
The invasive red swamp crayfish Procambarus clarkii is a human-mediated introduced species in the Iberian Peninsula. The species was introduced for economic reasons in the south of the Peninsula, but it is currently abundant and widespread in Portugal and Spain. As an invasive species, it is regulated by different laws in the Iberian Peninsula. Thus, although exploitation of this crayfish is permitted by the central government in Spain, the species is subjected to severe restrictions in Portugal. Moreover, regional governments in Spain only allow recreational fishing of P. clarki, except in southern Spain where there is an industrial activity based on the red swamp crayfish. We propose compromise measures in order to reconcile the economic exploitation of this aquatic resource and environmental concerns. The proposal mainly consists of the sale of live male specimens of P. clarkii and of dead (processed) female specimens. Biological invasion resulting in new established populations of P. clarkii in the wild would therefore be impossible. Transformation of P. clarkii into an economic resource with minimum environmental hazard seems feasible.
Realistic assessments of the ecological status of benthic habitats, as requested by European directives such as the Water Framework Directive and the European Marine Strategy Framework Directive, require biotic indices capable of detecting anthropogenic impact without having preliminary knowledge of the occurring pressures. In this context, a new general-purpose biotic index (GPBI) based on the deviation of benthic macrofauna community composition and structure from a valid reference (i.e., good ecological status) is proposed. GPBI is based on the assumption that as a site becomes impacted by a pressure, the most sensitive species are the first to disappear, and that stronger impacts lead to more important losses. Thus, it explicitly uses the within-species loss of individuals in the tested station in comparison to one or several reference stations as the basis of ecological status assessment. In this study, GPBI is successfully used in four case studies considering the impact of diversified pressures on benthic fauna: (1) maerl extraction in the northern Bay of Biscay, (2–3) dredging and trawling in the North Sea, and (4) hypoxic events at the seafloor in the Gullmarfjord. Our results show that GPBI was able to efficiently detect the impact of the different physical disturbances as well as that of hypoxia and that it performs better than commonly used pressure-specific indices (M-AMBI and TDI). Signal detection theory was used to propose a sound good/moderate ecological quality status boundary, and recommendations for future monitoring are also provided based on the reported performance of GPBI.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.