Deterioration of soft-bottom benthos along the Swedish Skagerrak coast
نویسندگان
چکیده
Oxygen deficiency in the near-bottom water associated with eutrophication has been shown to have negative impacts on marine benthos in many Scandinavian waters. In the present study, the benthic fauna and the sedimentary habitat have been studied between 7 and 34 m depth; at 14 stations in three Swedish fjords in four different years, and at 12 stations along the Swedish coast in three different years. Ignition loss of the top sediment indicated generally enriched conditions. The benthic fauna showed temporal declines in number of species, numerical abundance and biomass, particularly since the first samplings in 1976 at the fjord stations, and in 1987 at the coastal stations. Benthic macrofauna was lacking at some stations and very low numbers were recorded in several samples. Highest quantities were recorded at the deepest fjord and coastal stations. Multivariate analysis showed that the faunal composition changed with time. Analysis of sediment profile images classified the benthic habitat as disturbed with a thin vertical depth distribution of the apparent redox potential discontinuity. It is the first time reductions in benthic fauna have been shown to occur in relatively shallow waters over large coastal areas at the Swedish Skagerrak coast. The cause of the deterioration of the fauna is suggested to be low oxygen concentrations at the bottom in association with detached vegetation, leading to organic enrichment and locally even to anoxic sediment conditions. D 2005 Elsevier B.V. All rights reserved.
منابع مشابه
Dynamics of the Freshwater-influenced Surface Layers in the Skagerrak
The Skagerrak receives large amounts of freshwater, both in the form of rather low-saline waters from the Baltic Sea and the southern North Sea and in pure form from local rivers. These waters, mixed with the underlying Atlantic Water, participate in a variable, mainly wind-driven, cyclonic surface circulation in the Skagerrak. This paper presents a thorough analysis of hydrographic data to pro...
متن کامل374-377 Baden.p65
Seagrasses are aquatic flowering plants that occur worldwide and may be abundant on soft and sandy bottoms along coastal margins (1). In recent decades, a decrease in aerial extension has occurred mainly along industrialized coasts. This is documented throughout many distributional areas (2) and is one reason why seagrasses are listed in the Rio-declaration (1992/93:13) as habitats worthy of pr...
متن کاملSwedish Plectida (Nematoda). Part 7. Setostephanolaimus tchesunovi sp. n. from the west coast of Sweden.
A new species of Setostephanolaimus, S. tchesunovi sp. n., is described from bottom sediments collected in the Skagerrak and Gullmarn Fjord off the west coast of Sweden. It is characterised by 1.0-1.3 mm long body, outer labial setae 6.5-8.5 µm long, cephalic setae 9-11 µm long, subcephalic setae 4-6 µm long, transversely-oval amphid, female with monodelphic opisthodelphic reproductive system, ...
متن کاملFluxes of Water and Nutrients within and into the Skagerrak
Results from simultaneous velocity, salinity and nutrient measurements within the Southern Jutland Current and in the Skagerrak are presented. The measurements were undertaken during the 1990 and 1994 period along three sections perpendicular to the northwest coast of Denmark with the main purpose of estimating the importance of the Southern Jutland Current as a carrier of nutrients and contami...
متن کامل