Posidonia oceanica meadows are facing global threats mainly due to episodic heat waves. In a meso... more Posidonia oceanica meadows are facing global threats mainly due to episodic heat waves. In a mesocosm experiment, we aimed at disentangling the molecular response of P. oceanica under increasing temperature (20 °C-32 °C). The experiment was carried out in spring, when heat waves can potentially occur and plants are putatively more sensitive to heat stress, since they are deprived in carbohydrates reserves after the cold winter months. We aimed to identify the activation of different phases of the cellular stress response (CSR) reaction and the responsive genes activated or repressed in heated plants. A molecular traffic light was proposed as a response model including green (protein folding and membrane protection), yellow (ubiquitination and proteolysis) and red (DNA repair and apoptosis) categories. Additionally, we estimated phenological trait variations to complement the information obtained from the molecular proxies of stress. Despite reduced leaf growth rate, heated plants di...
ABSTRACT The influence of eutrophication associated with the presence of coastal constructions (d... more ABSTRACT The influence of eutrophication associated with the presence of coastal constructions (dykes, quays and seaports) and several natural phenomena over the benthic biological communities in a bay of southeastern Iberia (Aguilas, Murcia) is studied in this work. This bay has an area of 6.3 km2, where a small floodway, belonging to a drainage system of 49 km2 discharge. Eighty-five per cent of its shoreline is occupied by an industrial port, and an artificial beach. Due to the semi-arid character of this zone, periodical high intensity rains occur, causing floods with a great quantity of suspended materials that are discharged into the sea through the drainage streams. This significantly conditions the biological functioning of the planktonic and benthic marine populations in the affected littoral zone. The analysis of the sediments, and of the physical and chemical parameters, shows that the constructions built in the bay make it difficult for the fine materials poured into it after the floods to be washed away, thus prolonging the eutrophication associated with natural phenomena. The cartography of the bay clearly shows the effects of these periodical earth-carrying floods on the structure of the Posidonia oceanica meadows, and on the distribution of the fine materials. Comparison of recent aerial photographs reveals regression symptoms of the P. oceanica meadow associated with coastal works. The analysis of the biocoenosis diversity of the P. oceanica and the soft-bottoms shows different states of succession in relation to the degree of perturbation.
Reverse osmosis membranes at many desalination plants are disinfected by periodic shock treatment... more Reverse osmosis membranes at many desalination plants are disinfected by periodic shock treatments with sodium metabisulphite, which have potentially toxic effects to the environment for marine life, although no empirical and experimental evidence for this is yet available. The aim of this study was to characterise for the first time, the physico-chemical modification of the marine environment and its biological effects, caused by hypersaline plumes during these membrane cleaning treatments. The case study was the Maspalomas II desalination plant, located in the south of Gran Canaria (Canary Islands, Spain). Toxicity bioassays were performed on marine species characteristic for the infralittoral soft bottoms influenced by the brine plume (Synodus synodus and Cymodocea nodosa), and revealed a high sensitivity to short-term exposure to low sodium metabisulphite concentrations. The corrective measure of incorporating a diffusion system with Venturi Eductors reduced nearly all the areas of influence, virtually eliminating the impact of the disinfectant.
Journal of Experimental Marine Biology and Ecology, 2007
Here we studied the effects of adding organic carbon and nutrients to sediment on the physiology ... more Here we studied the effects of adding organic carbon and nutrients to sediment on the physiology and survival of the seagrass Posidonia oceanica in a field experiment in the Medes Islands (NE Spain). Nine randomly selected plots were established at a depth of 10 m; three were ...
ABSTRACT There are major concerns in the Mediterranean Sea over the effects of hypersaline efflue... more ABSTRACT There are major concerns in the Mediterranean Sea over the effects of hypersaline effluents from seawater desalination plants on seagrass communities. However, knowledge concerning the specific physiological capacities of seagrasses to tolerate or resist salinity increases is still limited. In this study, changes in the photosynthetic characteristics, pigment content, leaf light absorption, growth and survival of the seagrass Cymodocea nodosa were examined across a range of simulated hypersaline conditions. To this end, large plant fragments were maintained under salinities of 37 (control ambient salinity), 39, 41 and 43 (practical salinity scale) in a laboratory mesocosm system for 47 days. At the end of the experimental period, net photosynthesis exhibited a modest, but significant, decline (12e17%) in all tested hypersaline conditions (39e43). At intermediate salinity levels (39e41), the decline in photosynthetic rates was mainly accounted for by substantial increases in respiratory losses (approximately 98% of the control), the negative effects of which on leaf carbon balance were offset by an improved capacity and efficiency of leaves to absorb light, mainly through changes in accessory pigments, but also in optical properties related to leaf anatomy. Conversely, inhibition of gross photosynthesis (by 19.6% compared to the control mean) in the most severe hypersaline conditions (43) reduced net photosynthesis. In this treatment, the respiration rate was limited in order to facilitate a positive carbon balance (similar to that of the control plants) and shoot survival, although vitality would probably be reduced if such metabolic alterations persisted. These results are consistent with the ecology of Mediterranean C. nodosa populations, which are considered to have high morphological and physiological plasticity and a capacity to grow in a wide variety of coastal environments with varying salinity levels. The results from this study support the premise that C. nodosa has a higher tolerance to hypersaline conditions than the highly sensitive Posidonia oceanica, the other dominant Mediterranean seagrass, which is limited to marine environments with stable salinities.
Posidonia oceanica meadows are facing global threats mainly due to episodic heat waves. In a meso... more Posidonia oceanica meadows are facing global threats mainly due to episodic heat waves. In a mesocosm experiment, we aimed at disentangling the molecular response of P. oceanica under increasing temperature (20 °C-32 °C). The experiment was carried out in spring, when heat waves can potentially occur and plants are putatively more sensitive to heat stress, since they are deprived in carbohydrates reserves after the cold winter months. We aimed to identify the activation of different phases of the cellular stress response (CSR) reaction and the responsive genes activated or repressed in heated plants. A molecular traffic light was proposed as a response model including green (protein folding and membrane protection), yellow (ubiquitination and proteolysis) and red (DNA repair and apoptosis) categories. Additionally, we estimated phenological trait variations to complement the information obtained from the molecular proxies of stress. Despite reduced leaf growth rate, heated plants di...
ABSTRACT The influence of eutrophication associated with the presence of coastal constructions (d... more ABSTRACT The influence of eutrophication associated with the presence of coastal constructions (dykes, quays and seaports) and several natural phenomena over the benthic biological communities in a bay of southeastern Iberia (Aguilas, Murcia) is studied in this work. This bay has an area of 6.3 km2, where a small floodway, belonging to a drainage system of 49 km2 discharge. Eighty-five per cent of its shoreline is occupied by an industrial port, and an artificial beach. Due to the semi-arid character of this zone, periodical high intensity rains occur, causing floods with a great quantity of suspended materials that are discharged into the sea through the drainage streams. This significantly conditions the biological functioning of the planktonic and benthic marine populations in the affected littoral zone. The analysis of the sediments, and of the physical and chemical parameters, shows that the constructions built in the bay make it difficult for the fine materials poured into it after the floods to be washed away, thus prolonging the eutrophication associated with natural phenomena. The cartography of the bay clearly shows the effects of these periodical earth-carrying floods on the structure of the Posidonia oceanica meadows, and on the distribution of the fine materials. Comparison of recent aerial photographs reveals regression symptoms of the P. oceanica meadow associated with coastal works. The analysis of the biocoenosis diversity of the P. oceanica and the soft-bottoms shows different states of succession in relation to the degree of perturbation.
Reverse osmosis membranes at many desalination plants are disinfected by periodic shock treatment... more Reverse osmosis membranes at many desalination plants are disinfected by periodic shock treatments with sodium metabisulphite, which have potentially toxic effects to the environment for marine life, although no empirical and experimental evidence for this is yet available. The aim of this study was to characterise for the first time, the physico-chemical modification of the marine environment and its biological effects, caused by hypersaline plumes during these membrane cleaning treatments. The case study was the Maspalomas II desalination plant, located in the south of Gran Canaria (Canary Islands, Spain). Toxicity bioassays were performed on marine species characteristic for the infralittoral soft bottoms influenced by the brine plume (Synodus synodus and Cymodocea nodosa), and revealed a high sensitivity to short-term exposure to low sodium metabisulphite concentrations. The corrective measure of incorporating a diffusion system with Venturi Eductors reduced nearly all the areas of influence, virtually eliminating the impact of the disinfectant.
Journal of Experimental Marine Biology and Ecology, 2007
Here we studied the effects of adding organic carbon and nutrients to sediment on the physiology ... more Here we studied the effects of adding organic carbon and nutrients to sediment on the physiology and survival of the seagrass Posidonia oceanica in a field experiment in the Medes Islands (NE Spain). Nine randomly selected plots were established at a depth of 10 m; three were ...
ABSTRACT There are major concerns in the Mediterranean Sea over the effects of hypersaline efflue... more ABSTRACT There are major concerns in the Mediterranean Sea over the effects of hypersaline effluents from seawater desalination plants on seagrass communities. However, knowledge concerning the specific physiological capacities of seagrasses to tolerate or resist salinity increases is still limited. In this study, changes in the photosynthetic characteristics, pigment content, leaf light absorption, growth and survival of the seagrass Cymodocea nodosa were examined across a range of simulated hypersaline conditions. To this end, large plant fragments were maintained under salinities of 37 (control ambient salinity), 39, 41 and 43 (practical salinity scale) in a laboratory mesocosm system for 47 days. At the end of the experimental period, net photosynthesis exhibited a modest, but significant, decline (12e17%) in all tested hypersaline conditions (39e43). At intermediate salinity levels (39e41), the decline in photosynthetic rates was mainly accounted for by substantial increases in respiratory losses (approximately 98% of the control), the negative effects of which on leaf carbon balance were offset by an improved capacity and efficiency of leaves to absorb light, mainly through changes in accessory pigments, but also in optical properties related to leaf anatomy. Conversely, inhibition of gross photosynthesis (by 19.6% compared to the control mean) in the most severe hypersaline conditions (43) reduced net photosynthesis. In this treatment, the respiration rate was limited in order to facilitate a positive carbon balance (similar to that of the control plants) and shoot survival, although vitality would probably be reduced if such metabolic alterations persisted. These results are consistent with the ecology of Mediterranean C. nodosa populations, which are considered to have high morphological and physiological plasticity and a capacity to grow in a wide variety of coastal environments with varying salinity levels. The results from this study support the premise that C. nodosa has a higher tolerance to hypersaline conditions than the highly sensitive Posidonia oceanica, the other dominant Mediterranean seagrass, which is limited to marine environments with stable salinities.
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