1,738 publications from this institution
Three decades following the onset of efforts to revert widespread eutrophication of coastal ecosystems, evidence of improvement of ecosystem status is growing. However, cumulative pressures have developed in parallel to eutrophication, including those associated with climate change, such as warming, deoxygenation, ocean acidification and increased runoff. These additional pressures risk countering efforts to mitigate eutrophication and arrest coastal ecosystems in a state of eutrophication despite the efforts and significant resources already invested to revert coastal eutrophication. Here we argue that the time has arrived for a broader, more comprehensive approach to intervening to control eutrophication. Options for interventions include multiple levers controlling major pathways of nutrient budgets of coastal ecosystems, i.e. nutrient inputs, which is the intervention most commonly deployed, nutrient export, sequestration in sediments, and emissions of nitrogen to the atmosphere as N2 gas (denitrification). The levers involve local-scale hydrological engineering to increase flushing and nutrient export from (semi)enclosed coastal systems, ecological engineering such as sustainable aquaculture of seaweeds and mussels to enhance nutrient export and restoration of benthic habitats to increase sequestration in sediments as well as denitrification, as well as geo-engineering approaches including, with much precaution, aluminum injections in sediments. These proposed supplementary management levers to reduce eutrophication involve ecosystem-scale intervention and should be complemented with policy actions to protect benthic ecosystem components.
Abstract Past environmental conditions in the Mediterranean Sea have been proposed as main drivers of the current patterns of distribution of genetic structure of the seagrass Posidonia oceanica , the foundation species of one of the most important ecosystems in the Mediterranean Sea. Yet, the location of cold climate refugia (persistence regions) for this species during the Last Glacial Maximum (LGM) is not clear, precluding the understanding of its biogeographical history. We used Ecological Niche Modelling together with existing phylogeographic data to locate Pleistocene refugia in the Mediterranean Sea and to develop a hypothetical past biogeographical distribution able to explain the genetic diversity presently found in P. oceanica meadows. To do that, we used an ensemble approach of six predictive algorithms and two Ocean General Circulation Models. The minimum SST in winter and the maximum SST in summer allowed us to hindcast the species range during the LGM. We found separate glacial refugia in each Mediterranean basin and in the Central region. Altogether, the results suggest that the Central region of the Mediterranean Sea was the most relevant cold climate refugium, supporting the hypothesis that long-term persistence there allowed the region to develop and retain its presently high proportion of the global genetic diversity of P. oceanica .
Volumen 13 de la Coleccion Divulgacion (CSIC/Catarata). Los libros que forman la coleccion responden a la demanda de informacion de los ciudadanos sobre los temas que mas les afectan: salud, medio ambiente, transformaciones tecnologicas y sociales, etc. Cada volumen, elaborado por un equipo de especialistas en la materia, esta coordinado por un investigador del CSIC.
The notion that less productive marine planktonic communities tend to be heterotrophic was tested by synthesizing reported estimates of the relationships between the net community production or community respiration and gross primary production (GPP), allowing calculation of the threshold GPP separating less productive, heterotrophic communities from more productive, autotrophic ones. A total of 35 estimates of the threshold GPP were assembled, derived from reports of comparative analyses of individual regions (Mediterranean Sea, Atlantic Ocean, Southern Ocean, Pacific Ocean, and Indian Ocean) and global comparative analyses for open‐ocean and coastal environments, time‐series analyses of changes in planktonic metabolism at individual locations, experimental manipulations in mesocosms, and a semi‐empirical modeling exercise. Planktonic communities of the open ocean and continental shelf showed threshold GPP values ranging 30‐fold, from 0.34 mmol O 2 m −3 d −1 to 9.45 mmol O 2 m −3 d −1 , with those for estuarine and coastal locations reaching 50.60 mmol O 2 m −3 d −1 . Antarctic and ultra‐oligotrophic ecosystems showed the lowest threshold GPP values (<2.2 mmol O 2 m −3 d −1 ), with a general consistency across approaches for a given ecosystem. Plankton community respiration in the absence of or under low primary production is not negligible and is supported by semi‐labile dissolved organic carbon. The analysis of GPP thresholds suggests that allochthonous organic inputs to the less productive regions of the ocean must be in the order of mmol O 2 m −3 d −1 , consistent with recent estimates of allochthonous inputs of organic carbon to the ocean.
Nutrients (C, N, and P) and metals (iron, molybdenum, nickel, zinc, vanadium, copper, and cobalt) were determined in water and multiyear ice sampled along the Greenland current and Fram Strait in July 2007. Total metal and nutrient concentrations in ice varied fivefold to tenfold, for most elements, across the area sampled. Data show that some nutrients (i.e., NH 4 + ) and metals (i.e., Fe, Zn, V, Cu, Ni, Mo, and Co) are enriched in Arctic ice relative to surface seawaters, suggesting that ice melting is a significant source of metals to the receiving seawaters, particularly Fe and Zn whose concentrations were significantly ( t test, P < 0.05) more than 2 orders of magnitude higher in ice than in surface seawater.
