title: Intertidal macrofauna and environmental stress at a riverine-marine boundary.
abstract: A field experiment was carried out to test the effect of pore water salinity on the macrobenthic assemblages in an estuarine region of the Tagus estuary (Portugal) subjected to wide fluctuations in salinity. The conditions at the experimental site ranged from freshwater (minimum salinity 0.2) to mesohaline (maximum salinity 15.3). The experimental site was affected by an unexpected deposition of fluid mud during summer. Redundancy Analysis discriminated the experimental treatments along the first canonical ordination axis. The analysis also revealed an experimental gradient of increasing environmental stress, in which the minimal presence of organisms corresponded to treatments representing a high level of environmental stress. Sediment dynamics and saline fluctuations were the major factors that, together, determined the low macrofaunal abundance and species diversity at the experimental site. The most abundant macrofaunal species in this harsh environment were the polychaetes Hediste diversicolor and Streblospio shrubsolii.
authors: IBB-Institute for Biotechnology and Bioengineering, Center for Biological and Chemical Engineering, Instituto Superior Técnico (IST), Lisbon 1049-001, Portugal; Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, Vigo E-36310, Spain. Electronic address: aconde@ist.utl.pt.
authors: Anxo
authors: A
authors: Conde
authors: Júlio M
authors: JM
authors: Novais
authors: Jorge
authors: J
authors: Domínguez
mesh_terms: D000818:Animals; D044822:Biodiversity; D063366:Estuaries; D005618:Fresh Water; D019015:Geologic Sediments; D011077:Polychaeta / Q000502:physiology*; D011174:Portugal; D054712:Salinity; D012621:Seasons; D013312:Stress, Physiological
keywords: Environmental harshness; Fluid mud; Macrofaunal abundance; Saline fluctuations; Species richness; Tagus estuary