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Foraging ecology of five toothed whale species in the Northwest Iberian Peninsula, inferred using carbon and nitrogen isotope ratios
No full textThe feeding ecology and habitat use of the most frequently sighted and/or regularly reported stranded or by-caught toothed whale species of the North Western Iberian Peninsula (NWIP) were examined, with a special focus on their trophic position (TP) and relationships with their prey. With this aim, the stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) of common dolphin (Delphinus delphis), bottlenose dolphin (Tursiops truncatus), harbour porpoise (Phocoena phocoena), striped dolphin (Stenella coeruleolba) and long-finned pilot whale (Globicepahala melas) were analyzed in muscle samples taken from stranded and by-caught animals between 2004 and 2008. Stable isotopes were also measured in 17 species of fish and cephalopods previously identified as prey species, based on stomach content analyses, and in plankton. The trophic enrichment factors (TEF) were calculated for all five species and in addition, isotopic mixing models were applied to estimate the proportional contribution of each prey source to the diet of the common dolphin, which was the toothed whale species best sampled in our study. Plankton, fish and cephalopods exhibited an increasing trend in their δ13C values (from − 19.6‰ to − 15.3‰) along the offshore-inshore axis, with a less clear spatial pattern observed for δ15N values. Striped dolphins exhibited the lowest mean δ13C, δ15N and TP values (− 17.6‰, 10.8‰ and 4.3, respectively), which confirms the oceanic character of this species and its lower trophic position when compared to the other toothed whales analyzed. The common dolphin exhibited mean δ13C, δ15N and TP values that were at an intermediate level (− 17.0‰, 11.7‰ and 4.7, respectively) and results of the mixing model indicated that blue whiting (Micromesistius poutassou) was the main component of the diet. The harbour porpoise, bottlenose dolphin and pilot whale exhibited higher and very similar isotopic compositions and TPs. The mean TEF obtained between predators and their main prey were 1.4‰ for δ15N and 0.8‰ for δ13C. These results provide information on stable isotope incorporation data for toothed whales, which are essential if conclusions are to be drawn in issues concerning trophic structures and habitat use in the NWIP
Pescadores, conhecimento local e mudanças costeiras no litoral Português
Get PDFAs alterações climáticas são um dos maiores desafios que a sociedade enfrenta atualmente. As comunidades costeiras são particularmente vulneráveis, uma vez que estão crescentemente expostas aos riscos de erosão costeira e de subida do nível do mar. Os pescadores que vivem na e da costa têm uma visão privilegiada das mudanças costeiras e, em resultado da sua atividade, detêm um conhecimento que, apesar de não ser técnico, se baseia na experiência e é específico ao local. Em Portugal, este é um tema ainda pouco explorado e são raros os estudos das ciências sociais sobre as comunidades piscatórias. Este estudo pretende assim ser um contributo para uma temática que se encontra num estado ainda muito incipiente no nosso país. Para tal, analisamos os discursos de uma amostra de entrevistas em profundidade realizadas a pescadores de três zonas da costa portuguesa - Vagueira, Costa da Caparica e Quarteira. Os resultados revelam a existência de um conhecimento específico e profundo acerca da evolução da costa, das mudanças costeiras e das suas causas. Concluímos, através dos seus discursos, que os pescadores compreendem a complexidade das questões costeiras e a multiplicidade de fatores e usos\ud
que a influenciam. São também críticos em relação às opções técnicas que têm sido tomadas. Apesar de se verificarem algumas diferenças entre as três zonas de estudo na análise que os entrevistados fazem da eficácia das obras de proteção costeira, todos são capazes de propor medidas alternativas para mitigar o avanço o mar e a erosão costeira. Verifica-se ainda que este saber local não só não é incorporado nas soluções técnicas de gestão costeira, como os pescadores não são consultados aquando da tomada de decisões que os afetam diretamente. Tal poderá dever-se, por um lado, a uma desvalorização social da própria atividade pesqueira o que terá originado uma auto-avaliação negativa do valor social dos pescadores, refletindo-se numa incapacidade de reivindicação, só parcialmente ultrapassada quando estes são representados em associações ou sindicatos. Para além deste estatuto social inferior, parece haver também uma certa “incompatibilidade cultural” e de linguagem entre pescadores e especialistas, dificultando ainda mais o diálogo entre os dois e a incorporação do conhecimento local em decisões técnicas
Effects of environmental variability on different\ud trophic levels of the North Atlantic food web
No full textThe effects of environmental change on the biodiversity, structure and functioning of\ud
marine ecosystems is still poorly understood. In fact, very few studies have focused on changes in\ud
the at-sea foraging tactics of pelagic seabirds in relation to environmental stochasticity. Aiming at\ud
filling this knowledge gap, from 2005 to 2010 we directly measured the influence of climate (as\ud
driven by the North Atlantic Oscillation phenomenon) on (1) marine productivity (i.e. chlorophyll\ud
a concentration), (2) fish prey abundances and (3) the foraging behaviour of a top marine predator,\ud
the Cory’s shearwater Calonectris diomedea borealis. There was a dramatic change in the foraging\ud
strategy of the birds during 2010, which seems to be mostly related to a climatic event that\ud
occurred during the winter of 2009 to 2010. This event had a negative impact on the productivity\ud
of the surroundings of the breeding colony and decreased the abundance of pelagic prey fish,\ud
which in turn altered the spatial, feeding and trophic ecology of Cory’s shearwater and decreased\ud
their reproductive success. However, the negative trend in the abundance of pelagic prey (estimated\ud
from acoustic surveys and commercial fisheries landings) may be of concern because it\ud
does not seem to be only related to the climatic event of 2010. Long-term monitoring of the interactions\ud
between top predators, their prey and lower strata of the food web is crucial for a comprehensive\ud
assessment of the impacts that environmental variation may have on coastal ecosystems\ud
worldwide
Report of the Working Group on Anchovy and Sardine (WGANSA), 23–28 June 2012,Horta,Azores Portugal.
No full textParent–offspring dietary segregation of Cory’s shearwaters\ud breeding in contrasting environments
No full textIn pelagic seabirds, who often explore distant food resources, information is usually scarce on the level of trophic segregation between parents and their offspring.\ud
To investigate this issue, we used GPS tracking, stable\ud
isotopes and dietary information of Cory’s shearwaters\ud
Calonectris diomedea breeding in contrasting environments.\ud
Foraging trips at Selvagem Grande (an oceanic island)\ud
mainly targeted the distant African coast, while at Berlenga\ud
island (located on the continental shelf), shearwaters foraged mainly over nearby shelf waters. The degree of isotopic segregation between adults and chicks, based on\ud
d13C, differed markedly between the two sites, indicating\ud
that adult birds at Selvagem fed their chicks with a mixture\ud
of shelf and offshore pelagic prey but assimilated more\ud
prey captured on coastal shelf waters. Isotopic differences\ud
between age classes at Berlenga were much smaller and\ud
may have resulted from limited dietary segregation or from\ud
age-related metabolic differences. The diet of shearwaters\ud
was also very different between the two colonies, with\ud
offshore pelagic prey only being detected at Selvagem\ud
Grande. Our findings suggest that spatial foraging constraints influence resource partitioning between pelagic\ud
seabirds and their offspring and can lead to a parent–offspring dietary segregation
Geolocators Reveal Migration and Pre-Breeding\ud Behaviour of the Critically Endangered Balearic\ud Shearwater Puffinus mauretanicus
No full textUsing combined miniature archival light and salt-water immersion loggers, we characterise the year-round individual at-sea\ud
movements of Europe’s only critically endangered seabird, the Balearic shearwater Puffinus mauretanicus, for the first time.\ud
Focusing on the non-breeding period, we show that all of the 26 breeding birds tracked from their breeding site on\ud
Mallorca in the Mediterranean Sea successfully made a 2–4 month migration into the Atlantic Ocean, where they utilised\ud
well-defined core areas off Portuguese and French coasts. As well as identifying high-risk areas in the Atlantic, our results\ud
confirm that breeding birds spend most of the year concentrated around productive waters of the Iberian shelf in the\ud
western Mediterranean. Migration phenology appeared largely unrelated to the subsequent (distinctly synchronous)\ud
breeding attempt, suggesting that any carry-over effects were compensated for during a long pre-laying period spent over\ud
winter in the Mediterranean. Using the light and salt-water immersion data alone we were also able to characterise the\ud
pattern of pre-laying visits to the colony in considerable detail, demonstrating that breeding pairs appear to coordinate\ud
their over-day visits using a high frequency of night-time visits throughout the winter. Our study shows that geolocation\ud
technology is a valuable tool for assessing the spatial distribution of risks to this critically endangered species, and also\ud
provides a low-impact method for remotely observing the detailed behaviour of seabird species that may be sensitive to\ud
disturbance from traditional study methods
SAFESEA - Manual de Apoio para a Promoção de uma Pesca Mais Sustentável e de um Mar Seguro para Cetáceos
No full textA model for ocean circulation on the Iberian coast.
Get PDFWe used a three-dimensional model with generic vertical coordinate to investigate the structure of flow and transports on the Iberian shelf-slope region. Two different types of experiments were conducted. The first was a process-oriented study to investigate the role of thermohaline forcing in the generation and meridional variability of the poleward slope current. The second experiment was a more realistic simulation for the year of 1994, a period for which there are several long-term current\ud
meter data sets available. Comparisons between model, data and other published works have shown a reasonable agreement both qualitatively and quantitatively. The results obtained included the seasonal cycle with upwelling during the summer and a winter surface poleward current over the shelf, with a permanent undercurrent transporting Mediterranean Water along the Portuguese and Spanish slopes. The along-slope transports were predominant especially in the OMEX II–II study area. The meridional transport is poleward all year round, decreasing from winter to summer and from the south to the north. D 2002\ud
Elsevier Science B.V. All rights reserved
Campanha de Manutenção\ud e Construção de Ninhos Artificiais\ud para a Cagarra na Ilha da Berlenga
No full textAs Berlengas constituem o único local conhecido na costa continental portuguesa para a nidificação\ud
da Cagarra Calonectris diomedea borealis. A reduzida dimensão da sua população no final da década\ud
de 1980 e na década de 1990, levou a SPEA, juntamente com a Reserva Natural das Berlengas, a\ud
realizar uma campanha de conservação em 1999. Face ao sucesso desta campanha, que consistiu\ud
essencialmente na construção de ninhos artificiais (os quais foram posteriormente ocupados), foi\ud
realizada uma segunda campanha em Agosto de 2011, no âmbito do projecto FAME (Future of the\ud
Atlantic Marine Environment). Nesta campanha participaram 12 voluntários que colaboraram na\ud
construção de 50 novos ninhos e na manutenção de 34 ninhos artificiais
The Environmental History of Cetaceans in Portugal: Ten\ud Centuries of Whale and Dolphin Records
Get PDFThe history between cetaceans and humans is documented throughout time not only in reports, descriptions, and tales but also in legal documents, laws and regulations, and tithes. This wealth of information comes from the easy spotting and identification of individuals due to their large size, surface breathing, and conspicuous above water behaviour. This work is based on historical sources and accounts accounting for cetacean presence for the period between the 12th and 17th centuries, as well as scientific articles, newspapers, illustrations, maps, non-published scientific reports, and other grey literature from the 18th century onwards. Information on whale use in Portugal’s mainland has been found since as early as the 12th century and has continued to be created throughout time. No certainty can be given for medieval and earlier events, but both scavenging of stranded whales or use of captured ones may have happened. There is an increasing number of accounts of sighted, stranded, used, or captured cetaceans throughout centuries which is clearly associated with a growing effort towards the study of these animals. Scientific Latin species denominations only started to be\ud
registered from the 18th century onwards, as a consequence\ud
of the evolution of natural sciences in Portugal and increasing interest from zoologists. After the 19th century, a larger number of observations were recorded,\ud
and from the 20th century to the present day, regular\ud
scientific records have been collected. Research on the\ud
environmental history of cetaceans in Portugal shows a\ud
several-centuries-old exploitation of whales and dolphins,\ud
as resources mainly for human consumption, followed in\ud
later centuries by descriptions of natural history documenting strandings and at sea encounters. Most cetaceans\ud
species currently thought to be present in Portuguese mainland waters were at some point historically recorded