1,721,009 research outputs found
El paper de s’Albufera de Mallorca en la protecció del medi marí
Get PDF[cat] Multitud d’estudis han demostrat que les zones humides poden actuar com a filtres capaços de retenir nutrients i altres contaminants, evitant que arribin al medi marí. Per tant, són de vital importància per a mantenir els ecosistemes litorals en bones condicions. En el cas de s’Albufera de Mallorca, aquesta capacitat de retenció de nutrients no ha estat mai estudiada. Amb aquest treball es pretén començar a omplir el buit de coneixement existent en aquest aspecte per a que, en un futur, pugui ser aplicat a una gestió sostenible del paratge natural de s’Albufera de Mallorca. En aquest estudi, s’ha quantificat el fòsfor (total, orgànic i inorgànic) present a 532 mostres obtingudes a partir de 9 testimonis de sediment recollits a diferents localitzacions de s’Albufera (interior del canal, marge del canal i zones inundables). D’aquesta manera, es varen poder conèixer les variacions en les concentracions de fòsfor entre les diverses localitzacions i les seves respectives fondàries. La concentració de fòsfor total va ser significativament més elevada als testimonis recollits a zones inundables que als mostrejats al canal i al marge d’aquest. A més, en els primers, en cap moment s’hi varen observar concentracions molt baixes; mentre que, en els segons, a partir d’una certa profunditat la presència de fòsfor era mínima. Per una altra banda, es va trobar que la concentració de fòsfor inorgànic en la capa superficial dels testimonis recollits al canal i al seu marge predominava per sobre de la de fòsfor orgànic. En canvi, pels testimonis mostrejats a zones inundables, la concentració d’ambdós tipus de fòsfor va ser molt més equitativa
Efectos del aumento de la temperatura sobre el metabolismo de praderas de Cymodocea nodosa afectadas por la macroalga invasora Halimeda incrassata
No full text[spa] Hoy en día el cambio climático es la principal amenaza para nuestro entorno, con
el calentamiento global como una de sus principales consecuencias. El Mediterráneo
es especialmente sensible a este calentamiento y su biodiversidad marina se está
sometiendo a un proceso de tropicalización. En este estudio se ha evaluado
experimentalmente la respuesta de las tasas metabólicas (respiración (CR),
producción primaria bruta (GPP) y producción primaria neta (NCP)) de comunidades
de la fanerógama marina Cymodocea nodosa colonizada por la macroalga invasora
Halimeda incrassata a lo largo de un rango de temperaturas actual y proyectado para
finales del siglo XXI en el Mediterráneo, en dos estaciones del año. Las tasas
metabólicas se obtuvieron a partir de los cambios en la concentración de oxígeno,
medidos con sensores de oxígeno (IKS-Aquastar), dentro de cámaras de incubación
cerradas a temperaturas que van de 17 a 23ºC en primavera y de 25 a 33ºC en
verano. Usando medidas de alcalinidad y pH también se ha obtenido la concentración
de pCO2 (μatm) durante las incubaciones.
Las tasas metabólicas son sensibles al aumento de la temperatura, sobre todo
en verano, mientras que en primavera la macroalga invasora parece no estar activa. A
temperaturas más cálidas se produce un aumento de CR y GPP al estudiar los
macrófitos por separado, aumento que es mayor para CR que para GPP. En las
praderas invadidas, se confirma que la presencia de Halimeda incrassata disminuye
las tasas metabólicas a partir de un óptimo de temperatura. Con el aumento de la
temperatura estas comunidades también tienden a pasar de una NCP positiva donde
la comunidad es autotrófica, a una NCP negativa donde la comunidad es heterotrófica
con una tendencia a emitir CO2 y agotar la concentración de oxígeno. En resumen, un
efecto combinado de aumento de la temperatura y colonización por especies invasoras
lleva a estos ecosistemas a ser una fuente de carbono, con sus consecuentes efectos
negativos sobre el ambiente.[eng] Nowadays, climate change is the most important threat to our global
environment, with global warming as one of its main consequences. The
Mediterranean area is especially sensitive to this warming and its marine biodiversity is
undergoing rapid alteration and “tropicalization”. In this study we have experimentally
evaluated response of the metabolic rates as Community Respiration (CR), Gross
Primary Production (GPP) and Net Community Production (NCP), of seagrass
communities consisting of Cymodocea nodosa colonized by the invasive macroalgae
Halimeda incrassata. We assessed two different seasons with their ambient
temperature ranges and temperature increases as expected towards the end of the
21st century in the Mediterranean. The metabolic rates were obtained from changes in
oxygen concentration measured with oxygen-sensors (IKS-Aquastar) in incubation
chambers at temperatures ranging from 17ºC to 23ºC in spring and from 25ºC to 33ºC
in summer. Using point measurements of alkalinity and continuous pHNBS values we
also obtained the pCO2 (μatm) concentration during this incubations.
Metabolic rates are sensitive to temperature increments, especially in summer,
while during the spring the invasive macroalgae seem inactive. At higher temperatures
there is an increase of CR and GPP when macrophytes were evaluated separately.
This increase is higher for CR than for GPP. In invaded meadows, with both species
present, the presence of Halimeda incrassata causes the reduction of metabolic rates
starting from an optimum temperature. With temperature increases, these communities
tend to shift from a positive NCP of an autotrophic community, to a negative NCP of a
heterotrophic community, with a tendency to emit CO2 and exhaust the oxygen
concentration of the water column. In summary, the combined effect of a temperature
increase and colonization by invasive species reverts these ecosystems to a carbon
source instead of sink, with its consequent negative effects for the environment
Changes in dissolved oxygen due to anthropogenic disturbances and consequences for coastal marine life
Get PDF[eng] Increased anthropogenic pressures to coastal ecosystems in the last Century are
threatening coastal ecosystems, their biodiversity and ecosystems functioning. The two main
stressors affecting coastal systems are increases in nutrients loadings and global warming.
How coastal ecosystems will response to the combined effects of these two pressures remain
uncertain. In this Ph.D. dissertation I explore the consequences of global warming on
planktonic and benthic metabolism and on oxygen dynamics. I also explore the responses of
benthic communities to the main consequence of eutrophication, oxygen depletion, and the
environmental modulation of the responses of benthic organisms to hypoxia. Results confirm
a steeper increase in respiration rates than in production rates with warming in experimental
systems, whereas no differences were found between the responses of these metabolic rates
to temperature, within the current thermal range, in a natural system. Results suggest an
increase in the likelihood of hypoxia with warming. We also show that hypoxia thresholds
vary greatly across marine benthic organisms and that the conventional definition of 2 mg
O2/liter to designate waters as hypoxic is below the empirical sublethal and lethal oxygen
thresholds for half of the species tested, and explore the environmental modulation of these
thresholds.
All studied processes and results obtained within this work reveal, in summary, that
anthropogenic disturbances are significantly affecting coastal metabolism, and therefore,
oxygen dynamics, leading to oxygen declines due to the combined effects of eutrophication
and warming, threatening coastal biodiversity and ecosystems functioning.[cat] L'increment de les pressions antropogèniques als ecosistemes costaners durant el darrer segle
estan posant en perill la seva biodiversitat i el seu funcionament. L'increment en l’aport de
nutrients a les costes i l'escalfament global són les dues pressions més importants que afecten
als sistemes costaners. Cóm respondran aquests sistemes a l'efecte combinat d'aquestes dues
pressions és incert. En aquesta tesi doctoral exploro les conseqüències de l'escalfament global
en el metabolisme de les comunitats planctòniques i bentòniques i en les dinàmiques
d'oxigen. També exploro les respostes de les comunitats bentòniques a la major conseqüència
de l'eutrofització, la disminució de la concentració d'oxigen dissolt, i la modulació ambiental
de les respostes dels organismes bentònics a l hipòxia. Els resultats confirmen un major
increment en les taxes respiratòries que en les de producció amb l’escalfament en sistemes
experimentals, mentre no es troben diferències entre les respostes d'aquestes taxes
metabòliques a la temperatura, dins el seu rang tèrmic actual, en sistemes naturals. Els
resultats suggereixen que l'escalfament global augmentarà la probabilitat d'episodis hipòxics.
També mostram que els llindars d'hipòxia varien àmpliament en els diferents organismes
bentònics marins i que la definició tradicional d'hipòxia de 2 mg O2/litre per designar les
aigües com hipòxiques està per davall dels llindars de les concentracions letals i subletals
empíriques per a la meitat de les espècies testades. També exploram la modulació ambiental
d'aquests llindars.
Tots els processos estudiats i els resultats obtinguts en aquest treball revelen, en
resum, que les pertorbacions antropogèniques afecten significativament el metabolisme de les
comunitats costaneres i, per tant, les dinàmiques d'oxigen, produint una disminució en la
concentració d'oxigen a causa dels efectes combinats de l'eutrofització i l'escalfament, posant
en perill la biodiversitat costanera i el funcionament dels ecosistemes
Spatial and Temporal Variability of Seawater Chemistry in Coastal Ecosystems in the Context of Global Change
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Spatial and Temporal Variability of Seawater Chemistry in Coastal Ecosystems in the Context of Global Change
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Mediterranean seagrasses as carbon sinks: Methodological and regional differences
No full textThe increasing rates of CO2 due to anthropogenic activities are causing important potential climate threats for the Mediterranean Sea: ocean acidification and warming. In this region, two seagrass species, Posidonia oceanica and Cymodocea nodosa can play a crucial role in climate change mitigation. Through their metabolic activity, they can act as carbon sinks; buffer lowering pH values during the day and store carbon in the sediment underneath their meadows. In this study we analyse the metabolism synthesized from published data on seagrass community metabolism and from own results to evaluate trends through time of these two species comparing two methodologies: benthic chambers and multiparametric sensors. Furthermore, we analysed seasonal trends of both seagrass species´ metabolic rates and their variation between the Eastern and Western Mediterranean basins, with no significant results despite the clear visual trends. Our analysis revealed that there are significant differences between methodologies, with multiparametric sensors estimating higher rates, but unable to differentiate between habitats and useful to assess seagrass metabolism at a community level whereas benthic chambers are capable to evaluate rates at a seagrass species level. We found significant differences between the two Mediterranean regions for both methodologies, with highest rates of Net Community Production found in the Easter basin. At a species level, we found that Posidonia was more productive compared to Cymodocea. Furthermore, 86.7 % of the metabolic values reflected that the meadows were acting as carbon sinks in the Western basin.This work was funded by the Spanish Ministry of Economy and Competitiveness (Project MEDSHIFT, CGL2015-71809-P) and Project RTI2018-095441-B-C21 (SUMAECO) from the Spanish Ministry of Science, Universities and Innovation.Peer reviewe
Mediterranean seagrasses as carbon sinks: methodological and regional differences
No full textThe increasing rates of CO2 due to anthropogenic activities are causing important potential climate threats for the Mediterranean Sea: ocean acidification and warming. In this region, two seagrass species, Posidonia oceanica and Cymodocea nodosa, can play a crucial role in climate change mitigation. Seagrasses can act as carbon sinks, buffer lowering pH values during the day and storing carbon in the sediment underneath their meadows. However, available data documenting these processes are scattered and collected using different methodologies, which makes its interpretation and generalization very challenging. In this study, we analyzed published and unpublished data (collected for this study) on seagrass community metabolism to compare two methodologies, benthic chambers and multiparametric sensors, and evaluate trends through time for these two species. Furthermore, we analyzed seasonal trends of both seagrass species' metabolic rates and their variation between the eastern and western Mediterranean basins. Most evaluated meadows, 80.9 %, were autotrophic. Calculated metabolic rates differ between methodologies, with multiparametric sensors estimating rates almost an order of magnitude higher, 143.22±28.21 (SE) mmol O2 m-2 d-1 for net community production (NCP) compared to an average of 18.75±3.80 (SE) mmol O2 m-2 d-1 for measurements with benthic chambers. However, sensors are not able to differentiate between habitats and only useful to assess seagrass metabolism at a broader community level, whereas benthic chambers are capable of evaluating rates at the species level and confirm that P. oceanica is more productive compared to C. nodosa. We found similar metabolic rates in the eastern and western Mediterranean regions for P. oceanica with the benthic-chamber technique and higher NCP in the west based on sensor measurements.This work was funded by the Spanish Ministry of Economy and Competitiveness (MEDSHIFT, grant no. CGL2015-71809-P) and the Spanish Ministry of Science, Universities and Innovation (project SUMAECO, grant no. RTI2018-095441-B-C21). Susana Flecha was supported by a Margalida Comas postdoctoral scholarship, funded by the government of the Balearic Islands. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)
Experimental evaluation of the Response of coastal Mediterranean planktonic and benthic metabolic rates to warming
No full text[eng] The Mediterranean Sea has been identified as one of the hotspots for climate change. Intense warming in the Mediterranean Sea may have strong implications for biological activity and ecosystem functioning. To elucidate the effects of warming on planktonic and benthic metabolism, we performed experiments under different increasing temperature regimes, ranging from three to six different temperatures. The lowest range of temperatures assessed was of 2.6 A degrees C and the maximum was 7.5 A degrees C. Our results suggest that a 6 A degrees C warming of the Mediterranean waters may yield a mean increment in planktonic respiration rates of coastal communities of 24 %, higher than the mean increase expected for planktonic gross primary production (9 %). These results confirm earlier theories, and agree with previous experiments, of a higher increase in respiration rates than in primary production with warming, with the subsequent consequences for the carbon cycle, resulting in a negative feedback to climate warming, as ocean communities will capture less CO2
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