Effect of a possible interaction between pH and salinity on the growth of Posidonia oceanica (L.) Delile, 1813.

Reverse osmosis seawater desalination is a steadily growing industry in Mediterranean countries, but little information is available regarding its potential adverse environmental impact. Brine discharge from these plants has high salinity and a relatively low pH. The present paper describes mesocosm experiments carried out to determine the effect of a possible interaction between this simultaneous pH reduction and increase in salinity and the growth of the seagrass Posidonia oceanica (L.) Delile, 1813. Our results did not show any effect from the interaction between these two factors, although we did detect a significant growth reduction in plants when high salinities and low pH values occurred separately.La desalación de aguas marinas mediante ósmosis inversa es una actividad en desarrollo en la cuenca mediterránea cuyos posibles impactos ambientales son poco conocidos. El agua de rechazo de dichas plantas posee una elevada salinidad y un pH relativamente bajo. En el presente trabajo se realizaron experimentos en mesocosmos para estimar el efecto de una posible interacción entre dicho descenso del pH y el incremento de la salinidad sobre el crecimiento de la fanerógama marina Posidonia oceanica (L.) Delile, 1813. En los resultados obtenidos no se observó un efecto de la interacción entre ambos factores, pero sí una reducción significativa del crecimiento de la planta frente al aumento de la salinidad y al descenso del pH por separado.Instituto Español de Oceanografí

Atlas de las praderas marinas de España

Knowledge of the distribution and extent of seagrass habitats is currently the basis of management and conservation policies of the coastal zones in most European countries. This basic information is being requested through European directives for the establishment of monitoring programmes and the implementation of specific actions to preserve the marine environment. In addition, this information is crucial for the quantification of the ecological importance usually attributed to seagrass habitats due to, for instance, their involvement in biogeochemical cycles, marine biodiversity and quality of coastal waters or global carbon budgets. The seagrass atlas of Spain represents a huge collective effort performed by 84 authors across 30 Spanish institutions largely involved in the scientific research, management and conservation of seagrass habitats during the last three decades. They have contributed to the availability of the most precise and realistic seagrass maps for each region of the Spanish coast which have been integrated in a GIS to obtain the distribution and area of each seagrass species. Most of this information has independently originated at a regional level by regional governments, universities and public research organisations, which explain the elevated heterogeneity in criteria, scales, methods and objectives of the available information. On this basis, seagrass habitats in Spain occupy a total surface of 1,541,63 km2, 89% of which is concentrated in the Mediterranean regions; the rest is present in sheltered estuarine areas of the Atlantic peninsular regions and in the open coastal waters of the Canary Islands, which represents 50% of the Atlantic meadows. Of this surface, 71.5% corresponds to Posidonia oceanica, 19.5% to Cymodocea nodosa, 3.1% to Zostera noltii (=Nanozostera noltii), 0.3% to Zostera marina and 1.2% to Halophila decipiens. Species distribution maps are presented (including Ruppia spp.), together with maps of the main impacts and pressures that has affected or threatened their conservation status, as well as the management tools established for their protection and conservation. Despite this considerable effort, and the fact that Spain has mapped wide shelf areas, the information available is still incomplete and with weak precision in many regions, which will require an investment of major effort in the near future to complete the whole picture and respond to demands of EU directives

Atlas de las praderas marinas de España

Knowledge of the distribution and extent of seagrass habitats is currently the basis of management and conservation policies of the coastal zones in most European countries. This basic information is being requested through European directives for the establishment of monitoring programmes and the implementation of specific actions to preserve the marine environment. In addition, this information is crucial for the quantification of the ecological importance usually attributed to seagrass habitats due to, for instance, their involvement in biogeochemical cycles, marine biodiversity and quality of coastal waters or global carbon budgets. The seagrass atlas of Spain represents a huge collective effort performed by 84 authors across 30 Spanish institutions largely involved in the scientific research, management and conservation of seagrass habitats during the last three decades. They have contributed to the availability of the most precise and realistic seagrass maps for each region of the Spanish coast which have been integrated in a GIS to obtain the distribution and area of each seagrass species. Most of this information has independently originated at a regional level by regional governments, universities and public research organisations, which explain the elevated heterogeneity in criteria, scales, methods and objectives of the available information. On this basis, seagrass habitats in Spain occupy a total surface of 1,541,63 km2, 89% of which is concentrated in the Mediterranean regions; the rest is present in sheltered estuarine areas of the Atlantic peninsular regions and in the open coastal waters of the Canary Islands, which represents 50% of the Atlantic meadows. Of this surface, 71.5% corresponds to Posidonia oceanica, 19.5% to Cymodocea nodosa, 3.1% to Zostera noltii (=Nanozostera noltii), 0.3% to Zostera marina and 1.2% to Halophila decipiens. Species distribution maps are presented (including Ruppia spp.), together with maps of the main impacts and pressures that has affected or threatened their conservation status, as well as the management tools established for their protection and conservation. Despite this considerable effort, and the fact that Spain has mapped wide shelf areas, the information available is still incomplete and with weak precision in many regions, which will require an investment of major effort in the near future to complete the whole picture and respond to demands of EU directives.Versión del edito

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”

Responses of two Mediterranean seagrasses to experimental changes in salinity

The aim of this study is to examine the effects of variations in salinity levels on growth and survival of two fast-growing Mediterranean seagrasses, Cymodocea nodosa and Zostera noltii. We also tested the capacity of C. nodosa to acclimate to a gradual increase in salinity and to discover how it responds to a sharp rise in salinity in combination with other factors, such as increases in temperature, seasonality and different plant-population origins. Several short-term (10 days) experiments were conducted under controlled conditions. For each experiment, ten marked shoots were placed in 5-l aquaria, where they were exposed to different salinity treatments (ranging from 2 to 72 psu). Growth and survival of both species were significantly affected by salinity. A significant effect between salinity and temperature on the shoot growth rate of C. nodosa was also detected, but not on shoot mortality. When C. nodosa plants were acclimated by gradually increasing the salinity level, it was observed that acclimatisation improved tolerance to salinity changes. A different response to salinity variations, depending on the origin of the plants or the season of the year, was also detected. These results indicated that Z. noltii plants tolerate conditions of hyposalinity better than C. nodosa, and that the tolerance range of C. nodosa may change depending on the temperature, the season or the population.This research was financed by an ACUAMED contract and by an FPI grant (FPI 01 A 002) from the Generalitat Valenciana

Salinity tolerance of the Mediterranean seagrass Posidonia oceanica: recommendations to minimize the impact of brine discharges from desalination plants

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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

Bioindicators, Monitoring, and Management Using Mediterranean Seagrasses: What Have We Learned from the Implementation of the EU Water Framework Directive?

Seagrasses are flowering plants that inhabit coastal and transitional waters. They colonize sedimentary seabeds (and to a lesser extent rocky substrates) and present unique adaptations to the marine environment. Seagrasses are especially sensitive to environmental deterioration and live in a world that is particularly threatened by human activity. The response of the plants and their associated communities to disturbances is relatively well known. This has facilitated the development of a large number of seagrass bioindicators based on biochemical, physiological, morphological, structural, demographic, and community measures, especially after the deployment of the EU Water Framework Directive (WFD) and to a lesser extent the implementation of the Marine Strategy Framework Directive. Bioindicators are at the interface between science and policy. In order for their use by managers for different purposes (monitoring, water quality assessment, long-term changes, etc.) to be robust and consistent, a clear definition of management goals is needed. The development of bioindicators must also be based on careful evaluation together with rigorous and transparent selection processes to ensure their scientific credibility. Here, we present bioindicator indices based on seagrasses that were developed with the context of the implementation of the WFD in Catalonia, NE Spain, to assess the ecological status of coastal and transitional water bodies. Ecological status includes aspects concerning both the quality of the biological community and the hydrological and chemical characteristics of the environment. For this reason, and to develop a WFD-compliant system for ecological status assessment based on Mediterranean seagrasses, we used multivariate techniques to combine different bioindicators, gathered from different levels within the biological organization, into single biotic indices (POMI and CYMOX, based on the species Posidonia oceanica and Cymodocea nodosa, respectively). We report how this was achieved and how the robustness and reliability of those indices were assessed through correlation with human pressures, uncertainty analysis, and intercalibration. Finally, besides their applicability, we discuss their shortcomings and what we, as seagrass biologists, have learned overall from responding to the challenges posed by the WFD and specifically by the part dealing with seagrasses.Peer reviewe