title: Freshwater scarcity effects on the aquatic macrofauna of a European Mediterranean-climate estuary.
abstract: In the Mediterranean-climate zone, recurrent drought events and increasing water demand generally lead to a decrease in freshwater input to estuaries. This water scarcity may alter the proper function of estuaries as nursery areas for marine species and as permanent habitat for estuarine species. A 12-year data set of the aquatic macrofauna (fish, decapod and mysid crustaceans) in a Mediterranean estuary (Guadalquivir estuary, South Spain) was analysed to test if water scarcity favours the nursery function of regional estuaries to the detriment of permanent estuarine inhabitants. Target species typically displayed a salinity-related distribution and estuarine salinisation in dry years resulted in a general upstream community displacement. However, annual densities of marine species were neither consistently higher in dry years nor estuarine species during wet years. Exceptions included the estuarine mysid Neomysis integer and the marine shrimp Crangon crangon, which were more abundant in wet and dry years, respectively. High and persistent turbidity, a collateral effect of water scarcity, altered both the structural (salinity-related pattern) and functional (key prey species and predator density) community characteristics, chiefly after the second drought period of the analysis. The observed high inter-year environmental variability, as well as species-specific effects of water scarcity, suggests that exhaustive and long-term sampling programmes will be required for rigorously monitoring the estuarine communities of the Mediterranean-climate region.
authors.affiliation: IFAPA Centro El Toruño, Camino Tiro de Pichón s/n, 11500 El Puerto de Santa María, Spain. Electronic address: quique.gonzalezortegon@andaluciajunta.es.
authors.forename: Enrique
authors.initials: E
authors.lastname: González-Ortegón
authors.affiliation: Instituto Español de Oceanografía, Apartado 2609, 11006 Cádiz, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Baldó
authors.affiliation: Instituto de Ciencias Marinas de Andalucía (CSIC), Avda. República Saharaui 2, 11519 Puerto Real, Cádiz, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Arias
authors.affiliation: Instituto de Ciencias Marinas de Andalucía (CSIC), Avda. República Saharaui 2, 11519 Puerto Real, Cádiz, Spain.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Cuesta
authors.affiliation: Departamento Biología Animal, Edificio C-1, Campus Universitario de Rabanales, Universidad de Córdoba, 14071 Córdoba, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Fernández-Delgado
authors.affiliation: IFAPA Centro El Toruño, Camino Tiro de Pichón s/n, 11500 El Puerto de Santa María, Spain.
authors.forename: César
authors.initials: C
authors.lastname: Vilas
authors.affiliation: Instituto de Ciencias Marinas de Andalucía (CSIC), Avda. República Saharaui 2, 11519 Puerto Real, Cádiz, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Drake
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000145:classification / Q000254:growth & development*; D017753:Ecosystem; D004784:Environmental Monitoring; D063366:Estuaries; D005618:Fresh Water / Q000032:analysis*; D013030:Spain; D014881:Water Supply / Q000032:analysis* / Q000706:statistics & numerical data
keywords: Aquatic macrofauna; Climatic cycle; Estuarine community; Freshwater inputs; Guadalquivir estuary; Water scarcity