Biological impacts of oil pollution and cleaning in the intertidal zone of exposed sandy beaches : Preliminary study of the ‘Prestige’ oil spill. Estuarine, Coastal and Shelf Science 65

Abstract On 13th September 2002, the oil tanker ''Prestige'' sunk off the Galician coast, causing one of the most important oil spills in history, which affected the entire coastline, particularly the exposed rocky shores and sandy beaches. Seventeen exposed sandy beaches were analysed along the Galician coast, in May 2003, and results were compared with previous data for September 1995 and 1996. The intertidal areas of the beaches were sampled in four tidal zones along the beach profile: swash, resurgence, retention and dry sand. Six cores of 0.05 m 2 were taken at each level and washed through a 1 mm mesh. Sediment samples were collected at each level for sediment analysis. The species were grouped into six main taxonomic groups: polychaetes, molluscs, marine crustaceans, semi-terrestrial crustaceans, insects and others. The total number of species was calculated in each group before and after the oil spill. The disturbance effect on each tidal level was determined. A decrease in the species richness was generally observed in all the studied beaches, although this decrease was not homogeneous in all the taxonomic groups. Polychaetes, insects, semi-terrestrial crustaceans and others lost species in all cases, while marine crustaceans did not show this tendency, losing species in some cases and gaining in others. The most affected beaches lost up to 66.7% of the total species richness after the oil spill. The most disturbed levels were swash, losing most of the polychaetes, and dry sand, with decrease in insects and semi-terrestrial crustaceans in many cases. Dry sand level received a high amount of oil and was more affected by grooming and cleaning activities where fuel and polluted material were removed, including algal wrack that is used by the supratidal macrofauna as food and shelter

Ecology of exposed sandy beaches in northern Spain: environmental factors controlling macrofauna communities

Thirty-four exposed sandy beaches on the northern coast of Spain (from 42°11′ to 43°44′N, and from 2°04′ to 8°52′ W; ca. 1000 km) were sampled over a range of beach sizes, beach morphodynamics and exposure rates. Ten equally spaced intertidal shore levels along six replicated transects were sampled at each beach. Sediment and macrofauna samples were collected using corers to a depth of 15 cm. Morphodynamic characteristics such as the beach face slope, wave environment, exposure rates, Dean's parameter and Beach State Index were estimated. Biotic results indicated that in all the beaches the community was dominated by isopods, amphipods and polychaetes, mostly belonging to the detritivorous-opportunistic trophic group. The number of intertidal species ranged from 9 to 31, their density being between 31 and 618 individuals m-2, while individuals per linear metre (m-1) ranged from 4962 to 17 2215. The biomass, calculated as total ash-free dry weight (AFDW) varied from 0.027 to 2.412 g m-2, and from 3.6 to 266.6 g m-1. Multiple regression analysis indicated that number of species significantly increased with proximity to the wind-driven upwelling zone located to the west, i.e., west-coast beaches hosted more species than east-coast beaches. The number of species increased with decreasing mean grain size and increasing beach length. The density of individuals m-2 increased with decreasing mean grain size, while biomass m-2 increased with increasing food availability estimated as chlorophyll-a concentration in the water column of the swash zone. Multiple-regression analysis indicated that chlorophyll-a in the water column increased with increasing western longitude. Additional insights provided by single-regression analysis showed a positive relationship between the number of species and chlorophyll-a, while increasing biomass occurred with increasing mean grain size of the beach. The results indicate that community characteristics in the exposed sandy beaches studied are affected by physical characteristics such as sediment size and beach length, but also by other factors dependent on coastal processes, such as food availability in the water column

Population structure, growth and production of the yellow clam Mesodesma mactroides (Bivalvia: Mesodesmatidae) from a high-energy, temperate beach in northern Argentina

The yellow clam Mesodesma mactroides (Bivalvia: Mesodesmatidae) was once the most abundant intertidal species on the Atlantic coast of northern Argentina and an important commercial resource in South America. This study of a population inhabiting the intertidal zone of the sheltered-dissipative sandy beach Santa Teresita documents the species' population biology, including demographic structure, growth and production during December 2004 and December 2006, and adumbrates the critical state of M. mactroides at present. A total of 3,015 M. mactroides were collected and measured, whereas individuals were found with an anterior-posterior shell length between 2 and 64 mm. A von Bertalanffy growth function with an asymptotic length (L∞) of 85 mm and a growth constant (K) of 0.47 year-1 was established from length-frequency distributions. The longevity of the species is estimated at approximately 6 years, and instantaneous mortality rate was about three times higher than 40 years ago. Besides, this study confirmed that the overall growth performance index (OGP) is habitat-specific and can be used to group M. mactroides and M. donacium from different areas into temperate and upwelling species. Furthermore, OGP is inversely correlated with the latitudinal distribution of Mesodesma populations. The intertidal biomass ranged between 0.06 and 0.07 g AFDM m-2 year-1. Individual production was observed to be highest at 47 mm length (0.35 g AFDM m-2 year-1), and annual production ranged between 0.12 and 0.19 g AFDM m-2 year-1, resulting in productivity values (P/B) between 1.84 and 2.93. The comparison of the results of the present study with those of growth studies conducted on M. mactroides 40 years ago revealed the following considerable differences in the population structure of M. mactroides, indicating the conservation status of this intertidal bivalve as endangered: (1) present growth rates are faster, but that the maximum length attained has decreased, (2) the numbers of individuals per square metre were many times higher in the past than in the present, (3) bivalves from the present work never reached the 'commercial size' of 60 mm and (4) 40 years ago, the population of M. mactroides was composed of up to three cohorts, whereas in this study, there was only one single cohort visible.Fil: Herrmann, Marko. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina. Johann Heinrich von Thünen Institute; AlemaniaFil: Fernandez Alfaya, Jose Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Lepore, Mauro L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Penchaszadeh, Pablo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Arntz, Wolf E.. Institute for Polar and Marine Research; Alemani

Impact of oil spill and posterior clean-up activities on wrack-living talitrid amphipods on estuarine beaches

A geomorphological and faunistic seasonal study of six estuarine beaches on Paranaguá Bay, Brazil, was abruptly interrupted when the Chilean ship "Vicuña" exploded and sank, spilling 291 tons of bunker fuel oil. The beaches sampled twice before the accident were affected by the oil spill deposition and the posterior clean-up activities. Neither drastic reduction in abundances nor occurrences of oil-covered individuals were registered. Significant variation in both amount of debris and talitrid amphipod densities was directly related to beach clean-up activities. A short (1-3 month) manual clean-up of polluted wrack resulted in an increase in talitrid abundances, with the local distribution expansion of one species, Platorchestia monodi, from three to six of the beaches sampled. The active migration and concentration of organisms at sites without wrack during cleaning activities and a massive and continuous recovery of new debris, characteristic of estuarine beaches, may contribute to the findings.<br>Um estudo sazonal da geomorfologia e fauna de seis praias estuarinas na baia de Paranaguá, Brasil, foi interrompido bruscamente pela explosão e posterior afundamento do navio chileno Vicuña, que derramou 291 toneladas de óleo bunker. As praias que foram afetadas pela deposição de óleo e pelas posteriores atividades de limpeza, tinham sido amostradas duas vezes antes do acidente. Nas coletas posteriores ao acidente não foram registradas nem reduções drásticas das abundâncias nem indivíduos impregnados por óleo. As significativas variações tanto da quantidade de detrito quanto nas densidades de anfipodes talitrídeos foram relacionadas às atividades de limpeza. Uma limpeza manual e de curta duração (1 a 3 meses) resultou num aumento das abundâncias dos talitrídeos, juntamente com o aumento da distribuição de uma das espécies, Platorchestia monodi, que de três passou a ser encontrada em seis praias amostradas.Os fatores que contribuíram para estes resultados foram, por um lado, a migração ativa e a concentração de organismos em locais sem detrito durante as atividades de limpeza, e por outro, o contínuo aporte de novo detrito característico das praias estuarinas