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Saurel C.,Bangor University | Saurel C.,IMAR Institute of Marine Research | Petersen J.K.,Danish Shellfish Center | Wiles P.J.,Bangor University | Kaiser M.J.,Bangor University
Marine Ecology Progress Series | Year: 2013

Field measurements of physical and biological parameters, together with the estimation of mass transport and estimation of clearance rates (for feeding rate) using a biodeposition method (defecation) were combined to improve the understanding of the limiting factors that affect the feeding rate of blue mussels in an intertidal commercial re-laid benthic mussel bed. The study used an in situ feeding rate method to describe one of the mechanisms that underpins mussel bed self-patterning. The feeding rate of mussels measured using the in situ method (defecation) closely matched the rate of the measured turbulent transport of chl a. This relationship suggested that the supply rate of food limited the growth of mussels in this system. Vertical food depletion ([chl a] <1 μg l-1; height <6 cm) was measured above the mussel bed, and horizontal food depletion (at 5 cm above the bed) was measured in the water column at both mussel patches as well as at adjacent bare patches and in between. Mussel size mirrored the measured food gradient such that larger mussels occurred at the edge compared with the middle of the patches of mussels. In this system, the high mussel feeding rate (2.9 l ind.-1 h-1), despite food depletion near the mussel bed, is due to the interaction of 3 hydrodynamic processes: vertical turbulent mixing, advection and re-suspension. These processes are themselves altered through a positive feedback mechanism associated with the mussel bed morphology. We found that the highest feeding rates are achieved when mussel beds are interspersed with patches of bare mud; thus stocking strategies that promote the formation of self-patterning should be encouraged © 2013 Inter-Research. Source


Gamito S.,University of Algarve | Chainho P.,University of Lisbon | Costa J.L.,University of Lisbon | Medeiros J.P.,University of Lisbon | And 2 more authors.
Ecological Modelling | Year: 2010

The brackish water amphipod Corophium orientale is the dominant macroinvertebrate species in the upper Mira estuary, a small mesotidal system located in the southwest coast of Portugal. As climate changes will increase the frequency and intensity of extreme events such as floods and droughts, these will have a negative effect on benthic estuarine invertebrates, namely C. orientale. In order to understand the effects of these events on C. orientale, a dynamic model, based on published information and calibrated with field data, was developed and different scenarios were tested. For model construction, the annual development of three cohorts of C. orientale, their growth rates, and the establishment of the timing of each cohort rise and extinction are introduced. This structure can be repeated indefinitely, for years, and few parameters are required. The model simulations highlight the need for refuge areas that enable a fast recovery of the amphipod population after an extreme event and the recolozination of the affected areas. © 2009 Elsevier B.V. All rights reserved. Source


Ferreira C.S.S.,Research Center on Natural Resources | Ferreira A.J.D.,Research Center on Natural Resources | De Lima J.L.M.P.,University of Coimbra | De Lima J.L.M.P.,IMAR Institute of Marine Research | Nunes J.P.,University of Aveiro
Bodenkultur | Year: 2011

This paper presents the methodology and the first results of a study that is being developed in the Ribeira dos Covões micro-catchment, located in central Portugal, to study the impact of different land uses and the urbanization process on spatio-temporal hydrological changes based on a multi-scale approach. The aim of this study is to contribute for a better understanding on how land use changes impact hydrological processes. This is critical for predicting urban floods in fast urbanized areas and their mitigation (e.g. real-time flood warning procedures), which has become crucial for planning, management, and supporting the sustainable development of the basin. Source


De Lima M.I.P.,IMAR Institute of Marine Research | De Lima M.I.P.,Polytechnic Institute of Coimbra | Santo F.E.,Institute of Meteorology | Ramos A.M.,University of Vigo | And 3 more authors.
Atmospheric Research | Year: 2013

Changes in the climatology of precipitation and surface air temperature are being investigated worldwide, searching for changes in variability, the mean and extreme events (maximum and minimum). By exploring recent adjustments in the climate of mainland Portugal, particularly in the intensity, frequency and duration of extreme events, this study investigates trends in selected specific indices that are calculated from daily precipitation data from 57 and surface air temperature data from 23 measuring stations scattered across the territory. Special attention is paid to regional differences and variations in seasonality. The data cover the periods 1941-2007 for precipitation, and 1941-2006 for temperature. They are explored at the annual and seasonal scales and for different sub-periods.Results show that trends in annual precipitation indices are generally weak and, overall, not statistically significant at the 5% level. Nevertheless, a decreasing trend is revealed by regional indices of total wet-day precipitation and extreme precipitation (above the 99th percentile). Seasonal precipitation exhibits significant decreasing trends in spring precipitation, while extreme heavy precipitation events, in terms of both magnitude and frequency, have become more pronounced in autumn. Results for winter and summer suggest that the extremes have not suffered any significant aggravation.Trends for air temperature are statistically more significant and marked than for precipitation and indicate general warming across the territory. This warming trend is revealed very consistently by the time series of individual stations and regional mean temperature, and is also consistent with the findings reported in other studies for Portugal and at the European scale. © 2012 Elsevier B.V. Source


Bettencourt R.,University of The Azores | Bettencourt R.,IMAR Institute of Marine Research | Pinheiro M.,Bioinformatics Unit | Egas C.,Advanced Services Unit | And 6 more authors.
BMC Genomics | Year: 2010

Background: Bathymodiolus azoricus is a deep-sea hydrothermal vent mussel found in association with large faunal communities living in chemosynthetic environments at the bottom of the sea floor near the Azores Islands. Investigation of the exceptional physiological reactions that vent mussels have adopted in their habitat, including responses to environmental microbes, remains a difficult challenge for deep-sea biologists. In an attempt to reveal genes potentially involved in the deep-sea mussel innate immunity we carried out a high-throughput sequence analysis of freshly collected B. azoricus transcriptome using gills tissues as the primary source of immune transcripts given its strategic role in filtering the surrounding waterborne potentially infectious microorganisms. Additionally, a substantial EST data set was produced and from which a comprehensive collection of genes coding for putative proteins was organized in a dedicated database, "DeepSeaVent" the first deep-sea vent animal transcriptome database based on the 454 pyrosequencing technology.Results: A normalized cDNA library from gills tissue was sequenced in a full 454 GS-FLX run, producing 778,996 sequencing reads. Assembly of the high quality reads resulted in 75,407 contigs of which 3,071 were singletons. A total of 39,425 transcripts were conceptually translated into amino-sequences of which 22,023 matched known proteins in the NCBI non-redundant protein database, 15,839 revealed conserved protein domains through InterPro functional classification and 9,584 were assigned with Gene Ontology terms. Queries conducted within the database enabled the identification of genes putatively involved in immune and inflammatory reactions which had not been previously evidenced in the vent mussel. Their physical counterpart was confirmed by semi-quantitative quantitative Reverse-Transcription-Polymerase Chain Reactions (RT-PCR) and their RNA transcription level by quantitative PCR (qPCR) experiments.Conclusions: We have established the first tissue transcriptional analysis of a deep-sea hydrothermal vent animal and generated a searchable catalog of genes that provides a direct method of identifying and retrieving vast numbers of novel coding sequences which can be applied in gene expression profiling experiments from a non-conventional model organism. This provides the most comprehensive sequence resource for identifying novel genes currently available for a deep-sea vent organism, in particular, genes putatively involved in immune and inflammatory reactions in vent mussels.The characterization of the B. azoricus transcriptome will facilitate research into biological processes underlying physiological adaptations to hydrothermal vent environments and will provide a basis for expanding our understanding of genes putatively involved in adaptations processes during post-capture long term acclimatization experiments, at "sea-level" conditions, using B. azoricus as a model organism. © 2010 Bettencourt et al; licensee BioMed Central Ltd. Source

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