Ictioplancton asociado a praderas de Posidonia oceanica durante la época estival en la reserva marina de Tabarca

El hábitat es un factor decisivo en la supervivencia de los estadios tempranos. Los objetivos de este trabajo se centran en describir el poblamiento ictioplantónico de la pradera de P. oceanica en la reserva marina de Tabarca, así comosu comportamiento según el periodo día-noche. Se calaron redes fijas a nivel de P. oceanica y a 2 m por encima de ella durante cinco días en julio de 2000. Se capturaron 353 larvas. Las familias más abundantes fueron Clupeidae, Sparidae, Engraulidae y Gobbidae, representando el 31%, el 27%, el 11% y el 6%, respectivamente. Especies de pequeño tamaño presentan capacidad de seleccionar el hábitat. Concluimos que la pradera de P. oceanica es un factor determinante de la estructura del poblamiento larvario de especies demersales. Palabras clave: Larvas de peces, Fanerógamas marinas, Refugio, Redes fijas de plancton.Habitat complexity plays a key role in survival in early stages of fish larvae. We investigated fish larvae assemblage and its relation with P. oceanica seagrass at the Tabarca Island Marine Reserve. Samples were taken using moored plankton nets at two depths (0 and 2 m from P. oceanica meadow) over five consecutive days in July 2000. Three hundred and fifty-three larvae were captured. The most abundant families were Clupeidae (31%), Sparidae (27%), Engraulidae (11%) and Gobiidae (6%). We observed that small fish larvae were able to select nursery areas. We conclude that the P. oceanica leaf canopy is a major factor in structuring the larval fish assemblages of some demersal species. Key words: Fish larvae, Seagrasses, Habitat shelter, Moored plankton nets.El hábitat es un factor decisivo en la supervivencia de los estadios tempranos. Los objetivos de este trabajo se centran en describir el poblamiento ictioplantónico de la pradera de P. oceanica en la reserva marina de Tabarca, así comosu comportamiento según el periodo día-noche. Se calaron redes fijas a nivel de P. oceanica y a 2 m por encima de ella durante cinco días en julio de 2000. Se capturaron 353 larvas. Las familias más abundantes fueron Clupeidae, Sparidae, Engraulidae y Gobbidae, representando el 31%, el 27%, el 11% y el 6%, respectivamente. Especies de pequeño tamaño presentan capacidad de seleccionar el hábitat. Concluimos que la pradera de P. oceanica es un factor determinante de la estructura del poblamiento larvario de especies demersales. Palabras clave: Larvas de peces, Fanerógamas marinas, Refugio, Redes fijas de plancton

Ictioplancton asociado a praderas de Posidonia oceanica durante la época estival en la reserva marina de Tabarca

Ichthyoplankton associated with P. oceanica meadows during the summer season in the Tabarca marine reserveHabitat complexity plays a key role in survival in early stages of fish larvae. We investigated fish larvae assemblage and its relation with P. oceanicaseagrass at the Tabarca Island Marine Reserve. Samples were taken using moored plankton nets at two depths (0 and 2 m from P. oceanica meadow) over five consecutive days in July 2000. Three hundred and fifty¿three larvae were captured. The mostabundant families were Clupeidae (31%), Sparidae (27%), Engraulidae (11%) and Gobiidae (6%). We observed that small fish larvae were able to select nursery areas. We conclude that the P. oceanica leaf canopy is a major factor in structuring the larval fish assemblages of some demersal species

Polychaete distribution pattern on the Valencian Community coast, Spanish Mediterranean

Changes in benthic community structure are strongly related to environmental factors, and we need to determine how these natural changes occur in order to interpret the possible changes associated with anthropogenic impacts. The aim of this survey was to characterize and classify the polychaete assemblages inhabiting unpolluted soft bottoms in the Spanish Mediterranean in relation to environmental factors. Thirteen localities were sampled at depths between 9 and 31 m, from 2004 to 2006. Multivariate techniques showed that the structure of polychaete assemblages detected in 2004 was consistent over time and correlations between polychaetes and environmental factors were detected. The study area comprises four kinds of communities mainly characterized by polychaete assemblages, sediment types, and depth.

Sensitivity of amphipods to sewage pollution

International audienceAmphipods are considered a sensitive group to pollution but here different levels of sensitivity were detected among species, by analysing the impact of five sewage outfalls, with different flow and treat- ment levels, on amphipod assemblages from the Castellon coast (NE Spain). Sewage pollution produced a decrease in the abundance and richness of amphipods close to the outfalls. Most of the species showed high sensitivity, particularly species such as Bathyporeia borgi, Perioculodes longimanus and Autonoe spiniventris, whereas other species appeared to be more tolerant to the sewage input, such as Ampelisca brevicornis. These different responses could be related to burrowing behaviour, with fossorial species being more sensitive and domicolous species being less affected. Benthic amphipods, which live in direct contact with sediment, are widely used for bioassay and numerous species are usually employed in ecotoxicology tests for diverse contaminants. In order to consider amphipods for monitoring and biodiversity programmes, it is important to establish the degree of sensitivity of each species to different sources of pollution

Echinoderms as indicators of brine discharge impacts

Echinoderms are osmoconformer organisms and are expected to be very sensitive to brine discharges. The objective of this study is to examine the use of echinoderms as early warning indicators of the impact of brine discharges and its application in the management of desalination discharges. We sampled using visual census along transect lines, for nine consecutive years and in three different stations, i.e. before the seawater reverse osmosis desalination plant began operating and thereafter. One year after the plant operation, echinoderms disappeared from the localities affected by the desalination brine. When the desalination brine was diluted with seawater prior to discharge, it was observed a recovery of echinoderm densities in these localities. Therefore, echinoderm populations may be used as early indicators to monitor impacts associated with a desalination brine discharge, but also to detect a possible recovery of a previously impacted area when additional mitigation measures to reduce the impact of brine discharge have been implemented.This project was financially supported by the Water Consortium “Mancomunidad de Canales del Taibilla”

A methodology for applying Taxonomic Sufficiency and benthic biotic indices in two Mediterranean areas

Biotic indices have been developed to summarise information provided by benthic macroinvertebrates, but their use can require specialized taxonomic expertise as well as a time-consuming operation. Using high taxonomic level in biotic indices reduces sampling processing time but should be considered with caution, since assigning tolerance level to high taxonomic levels may cause uncertainty. A methodology for family level tolerance categorization based on the affinity of each family with disturbed or undisturbed conditions was employed. This family tolerance classification approach was tested in two different areas from Mediterranean Sea affected by sewage discharges. Biotic indices employed at family level responded correctly to sewage presence. However, in areas with different communities among stations and high diversity of species within each family, assigning the same tolerance level to a whole family could imply mistakes. Thus, use of high taxonomic level in biotic indices should be only restricted to areas where homogeneous community is presented and families across sites have similar species composition

Response of different benthic indices to diverse human pressures

International audienceThe interest in benthic indicators for soft-bottom marine communities has dramatically increased after a rather long period of relative stagnation due to the need for new tools to assess the status of marine waters, called for by the Clean Water Act and the Water Framework Directive. Our expertise on ben- thic communities has permitted us to gather a vast amount of data from diverse water bodies under unpolluted and polluted conditions (e.g., accidental oil spill, sewage, long-term anthropogenic estuarine constraints) in tidal estuaries, harbours, and on the coastal shelf from Atlantic Ocean and Mediterranean Sea. We compared the results of four biotic indices on the various available datasets: Shannon-Wiener H diversity, AMBI and BO2A, which divide the species into Ecological Groups, and ITI, which divides the species into trophic groups, and the agreement of Best Professional Judgement (BPJ) on the assessment of ecological conditions. Benthic indicators as "sentinel species", which is a particular species that by its presence or its relative abundance warns of possible unbalances in the surrounding environment or dis- tortions in community functions, was also tested. Indicators, BPJ and opportunist sentinel species gave similar ECoQS for the different sampling sites. We discuss the use of Biological Indicators as 'objective' or 'subjective' alternatives for assessing soft-bottom communities, and propose to employ simple methods such as BPJ and taxonomy sufficiency in such diagnostic approaches

Evolution of Posidonia oceanica seagrass meadows and its implications for management

Results of the monitoring network of the Posidonia oceanica meadows in the Valencia region in Spain are analysed. For spatial comparison the whole data set has been analysed, however, for temporal trends we only selected stations that have been monitored at least 6 years in the period of 2002–2011 (26 stations in 13 localities). At the south of the studied area, meadows are larger, and they have higher density and covering than that in the Valencia Gulf, excluding Oropesa meadow. Monitoring of P. oceanica meadows in the Valencia region in Spain indicates that most of them are stationary or they are increasing their density and covering while no decline was observed in the studied meadows. These results indicate that there is not a general decline of P. oceanica meadows and that the decline of P. oceanica, when it has been observed in other studies, is produced by local causes that may be managed at the local level. This study also reflects the importance of long series of direct data to analyse trends in the population dynamics for slow-growing species.Diputación de Alicante, Municipalities of El Campello Alicante and Calpe and the Spanish Ministry of Agriculture Food and Environment