Pitcher G.C.,South African Department of Environmental Affairs and Tourism |
Pitcher G.C.,University of Cape Town |
Figueiras F.G.,CSIC - Institute of Marine Research |
Hickey B.M.,University of Washington |
Moita M.T.,Institute Investigacao das Pescas e do Mar IPIMAR
Progress in Oceanography | Year: 2010
The upwelling systems of the eastern boundaries of the world's oceans are susceptible to harmful algal blooms (HABs) because they are highly productive, nutrient-rich environments, prone to high-biomass blooms. This review identifies those aspects of the physical environment important in the development of HABs in upwelling systems through description and comparison of bloom events in the Benguela, California and Iberia systems. HAB development is dictated by the influence of wind stress on the surface boundary layer through a combination of its influence on surface mixed-layer characteristics and shelf circulation patterns. The timing of HABs is controlled by windstress fluctuations and buoyancy inputs at the seasonal, event and interannual scales. Within this temporal framework, various mesoscale features that interrupt typical upwelling circulation patterns, determine the spatial distribution of HABs. The inner shelf in particular provides a mosaic of shifting habitats, some of which favour HABs. Changes in coastline configuration and orientation, and bottom topography are important in determining the distribution of HABs through their influence on water stratification and retention. A spectrum of coastline configurations, including headlands, capes, peninsulas, Rías, bays and estuaries, representing systems of increasing isolation from the open coast and consequent increasing retention times, are assessed in terms of their vulnerability to HABs. © 2010 Elsevier Ltd. All rights reserved.
Serra-Pereira B.,Institute Investigacao das Pescas e do Mar IPIMAR |
Afonso F.,University of Lisbon |
Farias I.,Institute Investigacao das Pescas e do Mar IPIMAR |
Joyce P.,Institute Investigacao das Pescas e do Mar IPIMAR |
And 2 more authors.
Helgoland Marine Research | Year: 2011
The reproductive processes of chondrichthyans are complex. Knowledge of the development and maturation of the oviducal gland is vital for understanding the reproductive biology of a species. This study represents the first contribution of this subject for skates. In the oviparous thornback ray, Raja clavata, oviducal gland development begins early in the developing stage with the formation of gland tubules and the distinct lamellae of each zone: club, papillary, baffle and terminal. Oviducal development is complete by the end of the developing stage when the storage and secretion of products is evident within the gland tubules of each zone. Periodic acid-Schiff and alcian blue histological staining showed that the secretory mucous cells of the club and papillary zones produce neutral and sulfated acid mucins. The last row of gland tubules of the papillary zone stains intensely for sulfated acid mucins. The baffle zone, which is responsible for the production of the egg capsule, represented 60-80% of the glandular zone of the oviducal gland. Sperm bundles were observed in the deeper recesses of the baffle zone during the maturation process, and during capsule extrusion, sperm were detected near the lumen. The terminal zone was composed of two types of gland tubules: serous (producing protein fibres) and mucous glands (producing sulfated acid mucins). © 2010 Springer-Verlag and AWI.
Rodhouse P.G.K.,British Antarctic Survey |
Pierce G.J.,University of Aberdeen |
Pierce G.J.,University of Aveiro |
Nichols O.C.,University of Massachusetts Dartmouth |
And 16 more authors.
Advances in Marine Biology | Year: 2014
Cephalopods are a relatively small class of molluscs (~. 800 species), but they support some large industrial scale fisheries and numerous small-scale, local, artisanal fisheries. For several decades, landings of cephalopods globally have grown against a background of total finfish landings levelling off and then declining. There is now evidence that in recent years, growth in cephalopod landings has declined. The commercially exploited cephalopod species are fast-growing, short-lived ecological opportunists. Annual variability in abundance is strongly influenced by environmental variability, but the underlying causes of the links between environment and population dynamics are poorly understood. Stock assessment models have recently been developed that incorporate environmental processes that drive variability in recruitment, distribution and migration patterns. These models can be expected to improve as more, and better, data are obtained on environmental effects and as techniques for stock identification improve. A key element of future progress will be improved understanding of trophic dynamics at all phases in the cephalopod life cycle. In the meantime, there is no routine stock assessment in many targeted fisheries or in the numerous by-catch fisheries for cephalopods. There is a particular need for a precautionary approach in these cases. Assessment in many fisheries is complicated because cephalopods are ecological opportunists and stocks appear to have benefited from the reduction of key predator by overexploitation. Because of the complexities involved, ecosystem-based fisheries management integrating social, economic and ecological considerations is desirable for cephalopod fisheries. An ecological approach to management is routine in many fisheries, but to be effective, good scientific understanding of the relationships between the environment, trophic dynamics and population dynamics is essential. Fisheries and the ecosystems they depend on can only be managed by regulating the activities of the fishing industry, and this requires understanding the dynamics of the stocks they exploit. © 2014 Elsevier Ltd.
Cervino S.,FARO |
Dominguez-Petit R.,CSIC - Institute of Marine Research |
Jardim E.,Institute Investigacao das Pescas e do Mar IPIMAR |
Jardim E.,European Commission - Joint Research Center Ispra |
And 3 more authors.
Fisheries Research | Year: 2013
Spawning stock biomass (SSB) is one of the most common measures of stock status. However recent research on reproductive potential has shown that alternative variables may be an improvement over SSB. In the case of European hake (Merluccius merluccius), it is known that large individuals produce more eggs by unit of body weight, and their quality is better than those of small individuals. Under these circumstances, application of reproductive potential may be pertinent in the implementation of the Johannesburg agreement, since it is not only the spawning biomass but also its age or length structure that defines stock productivity and its ability to achieve maximum sustainable yield (MSY). In this contribution we used an age-length structured population model to assess the impact of different reproductive indices (total spawning biomass, female spawning biomass and egg production) on MSY reference points. First, we analyzed how these different indices alter our perception about per recruit productivity. Second, we analyzed the quality of these alternative reproductive indices to explain and predict recruitment using different model structures (Ricker and Beverton-Holt) and Bayesian inference. Third, we combined per recruit models and stochastic stock-recruitment relationships to estimate the probability distributions of MSY biological reference points (MSY, Fmsy, Stockmsy, and Fcrash). Our results show that, for hake stocks where larger fish have a strong contribution to stock reproductive potential, use of alternative reproductive indices will affect estimations of stock sustainability. The change in perception of relative contribution of each length class is exhibited in two opposite ways: reproductive potential per recruit and the shape of the stock-recruitment relationship defined with steepness. In our case, the change from SSB to egg production, resulted in an increase in steepness which counteracted the depletion per recruit resulting in a larger Fmsy. © 2012 Elsevier B.V.
Bernardez P.,CSIC - Institute of Marine Research |
Prego R.,CSIC - Institute of Marine Research |
Giralt S.,CSIC - Institute of Earth Sciences Jaume Almera |
Esteve J.,University of Barcelona |
And 3 more authors.
Marine Geology | Year: 2012
A multidisciplinary study of the elemental geochemistry and mineralogical characteristics of the marine surficial sediment in the Northern Rias (NW Iberian Peninsula) has been carried out. The linkages between the marine sediment composition and their potential sources were examined.The influence of the river-borne sediments is only detected in the innermost part of the three Rias. Regional variations of the mineral assemblages are governed by the source-rock composition of the different geological complexes and the relative source-rock contribution controlled by the continental hydrology. Mineralogical composition of the Ortigueira Ria and adjacent shelf surficial sediments are mainly made up of mafic and ultramafic rocks of the Cape Ortegal complex indicated by the high content of Mg, Mn and chrysotile and riebeckite minerals. In areas nearby Ortegal complex the imprint of heavy minerals present in the surrounding rocks has also been recorded. Barqueiro and Viveiro Rias bed-sediments are influenced by granitic and metamorphic rocks from the Ollo de Sapo complex as revealed by the high contribution of muscovite and quartz.Mining activities in the continental domain left strong imprints on marine surficial sediments. Pyrite content is high in the innermost areas of the Ortigueira Ria since this mineral is exploited in the Mera River basin, whereas high muscovite percentages characterize the Viveiro Ria owing to the abundance of granitic rocks and its exploitation in the Landro River basin. Quartz content is high nearby Cape Estaca de Bares, induced by the presence of an important excavation of this material. © 2011 Elsevier B.V..
Clara Amorim M.P.,Instituto Superior Of Psicologia Aplicada |
Miguel Simoes J.,Instituto Superior Of Psicologia Aplicada |
Mendonca N.,Institute Investigacao das Pescas e do Mar IPIMAR |
Bandarra N.M.,Institute Investigacao das Pescas e do Mar IPIMAR |
And 2 more authors.
Journal of Experimental Biology | Year: 2010
Lusitanian toadfish males that provide parental care rely on acoustic signals (the boatwhistle) to attract females to their nest. We test the hypothesis that male quality, namely male size and condition that are relevant for parental success, is reflected in vocal activity and boatwhistle characteristics and thus advertised to females. We recorded 22 males over a week during the peak of the breeding season. Calling rate and calling effort (percentage of time spent calling) strongly reflected male condition (lipid content of somatic muscles) and to a smaller extent sonic muscle hypertrophy and larger gonads. Males in better condition (increased body lipid and relative higher liver mass) also contracted the sonic muscles at faster rate as shown by the shorter boatwhistle pulse periods. Amplitude modulation reflected the degree of sonic muscle hypertrophy. None of the measured male quality parameters were good predictors of boatwhistle duration and dominant frequency. Altogether this study strongly suggests that Lusitanian toadfish males advertise their quality to females primarily with boatwhistle calling rate and calling effort, which mainly reflect male condition. Because pulse period had low variability, consistent with the existence of a vocal central pattern generator, we suggest that males that sustain sonic muscles contraction at a very fast rate close to their physiological limit may be honestly advertising their quality (condition). Similarly, males that produce boatwhistles with higher amplitude modulation, a feature that seems dependent on sonic muscle hypertrophy, could be more attractive to females. © 2010. Published by The Company of Biologists Ltd.
Gameiro C.,University of Lisbon |
Zwolinski J.,Institute Investigacao das Pescas e do Mar IPIMAR |
Brotas V.,University of Lisbon
Hydrobiologia | Year: 2011
Tagus estuary is one of the largest estuaries of Western Europe. With the aim of unravelling the drivers of primary production in this shallow and turbid nutrient replete estuary, we tested the hypothesis that light availability is a major factor controlling phytoplankton production. Environmental parameters, phytoplankton biomass, community composition, and photosynthetic parameters were monitored at two sites in the estuary during a complete annual cycle. Despite the fact that nutrient concentrations were always above growth-limiting values, Chl a concentrations were relatively low throughout the study period. High water column turbidity, due to riverine inputs, promoted a rapid attenuation of light and created a compressed profile with optimal photosynthetic conditions. Therefore, the phytoplankton community, dominated by small cells, such as diatoms and cryptophycean flagellates, displayed highly photosynthetic efficiency and low light-saturated photosynthetic rates as a photo-acclimation response to low light conditions year-round. Primary production rate was unimodal, peaking in the summer months. In such estuarine system, gross primary production could thus be predicted by an existing robust empirical model based on pigment standing crop (Chl a), surface irradiance (E0) and optical depth (Zeup). Compared to other shallow estuaries, the Tagus can be classified as a low- to moderately productive estuary, being the turbidity-induced low light conditions the principal factor limiting phytoplankton growth. © 2011 Springer Science+Business Media B.V.
Uslu L.,Cukurova University |
Durmaz Y.,Ege University |
Duyar H.A.,Ondokuz Mayis University |
Bandarra N.M.,Institute Investigacao Das Pescas e do Mar IPIMAR
Journal of Animal and Veterinary Advances | Year: 2013
The present investigation was to study the nutritional value, fatty acid composition and α-tocopherol of the red macroalgae Rhodophyta (Antithamnion, Ceramium, Corallina and Laurencia sp.) in the Sinop Bay from Black Sea. The highest level of 20:5 (n-3) was 27.18% of Dry Weight (DW) for Antithamnion sp., however, the lowest level was 11.90% DW for Ceramium sp. The α-tocopherol content in samples showed marked variation among the four types of algae and it was max; 21.2±0.2 andmin; 8.5±0.3 μg g-1 DW. The highest level of total carotenoids was determined in the Antithamnion sp., contained as 1.69±0.46 mg g-1 DW. Nevertheless, the highest level of chlorophyll a was observed in the Laurencia sp. (0.26±0.01 mg g-1). The crude protein content of the Antithamnion sp. (28.1 ±0.3%) and Ceramium sp. (28.5±0.5%) was higher than the Corallina and Laurencia sp. As a result, Antithamnion sp., is a good source of lipids with a good level of EPA, total carotenoids and α-tocopherol and Ceramum sp., evidenced to be an excellent protein source. In Europe, the development of novel foods, such as functional foods could be a new possibility for the use of these macroalgae, especially for the protein, fatty acids and α-tocopherol-rich species in human nutrition. This present study results showed that these red macroalgae in the Sinop Bay could be utilized as functional ingredients for the valuable nutritional properties for seafood industries. © Medwell Journals, 2013.