Every year fisheries discard >10 million tonnes of fish. This provides a bounty for scavengers, yet the ecological impact of discarding is understudied. Seabirds are the best-studied discard scavengers and fisheries have shaped their movement ecology, demography and community structure. However, we know little about the number of scavenging seabirds that discards support, how this varies over time or might change as stocks and policy change. Here, we use a Bayesian bioenergetics model to estimate the number of scavenging birds potentially supported by discards in the North Sea (one of the highest discard-producing regions) in 1990, around the peak of production, and again after discard declines in 2010. We estimate that North Sea discards declined by 48% from 509,840 tonnes in 1990 to 267,549 tonnes in 2010. This waste had the potential to support 5.66 (95% credible intervals: 3.33-9.74) million seabirds in the 1990s, declining by 39% to 3.45 (1.98-5.78) million birds by 2010. Our study reveals the potential for fishery discards to support very large scavenging seabird communities but also shows how this has declined over recent decades. Discard bans, like the European Union's Landing Obligation, may reduce inflated scavenger communities, but come against a backdrop of gradual declines potentially buffering deleterious impacts. More work is required to reduce uncertainty and to generate global estimates, but our study highlights the magnitude of scavenger communities potentially supported by discards and thus the importance of understanding the wider ecological consequences of dumping fisheries waste. ; Publisher PDF ; Peer reviewed
Fundings: Natural Environment Research Council (GrantNumber(s): VertIBase project [NE/N01765X/1]) Department for Business, Energy and Industrial Strategy, UK Government (GrantNumber(s): Offshore Energy Strategic Environmental Assessment) ACKNOWLEDGMENTS We gratefully acknowledge the support of the crew and scientists of the MRV Scotia 2016 (0916S) and 2018 (1018S) cruises: Marianna Chimienti, Helen Wade, Laura Williamson, Ewan Edwards, Ross Culloch, Tom Evans, Sarah Fenn, David Hunter, Eric Armstrong, and Adrian Tait. This work was supported by the NERC VertIBase Project [NE/N01765X/1] and the UK Department for Business, Energy and Industrial Strategy's Offshore Energy Strategic Environmental Assessment Programme. ; Peer reviewed ; Publisher PDF
Dissertação de mestrado em Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra. ; Os ecossistemas marinhos têm vindo a enfrentar um aumento no número de ameaças como a exploração insustentável dos recursos marinhos (por exemplo a pesca excessiva), degradação e perda de habitats marinhos, efeitos da poluição, da introdução de espécies invasoras e efeitos das alterações climáticas. Uma possível forma de diminuir tais impactos é através da implementação de Áreas Marinhas Protegidas (Marine Protected Areas, MPAs), que desempenham um papel importante na conservação da biodiversidade e contribuem para a recuperação do ambiente marinho. No entanto a percentagem do oceano que está actualmente sob protecção (2.8%) é bastante baixo considerando um dos objectivos estabelecidos pela CBD (Convention on Biological Diversity): proteger pelo menos 10% da costa e áreas marinhas até 2020. As águas circundantes ao arquipélago das Berlengas têm um grande valor de conservação devido às suas características que levam à agregação de grande produtividade marinha, permitindo a subsistência de várias aves marinhas, algumas delas em perigo de extinção (como a Pardela-Balear Puffinus mauritanicus). Embora esta área esteja actualmente sob protecção, os limites da Área Marinha Protegida (MPA) não se sobrepõem totalmente à área definida como importante para as aves marinhas (marine Important Bird Area, mIBA) que foi estabelecida com base apenas na biodiversidade local. Os limites actuais da MPA das Berlengas foram definidos com a contribuição de informação de rastreamento das áreas de procura de alimento mais importantes para uma ave marinha predadora de topo com uma ampla distribuição, a Cagarra Calonectris diomedea, sobretudo durante a fase de alimentação às crias entre 2005 e 2008. Contudo, os limites da mIBA e MPA das Berlengas não foram avaliados usando informação de rastreamento de todo o ciclo reprodutivo da espécie durante vários anos (para englobar a estocasticidade ambiental inter-anual). O objectivo desta tese foi usar dados de rastreamento de uma ave marinha predadora de topo para definir importantes áreas de procura de alimento e avaliar a sua adequabilidade no estabelecimento de uma rede de Áreas Marinhas Protegidas ao longo de Portugal Continental. Mais especificamente este trabalho pretende responder às seguintes questões: (1) Que factores (ambientais ou antropogénicos) influenciam a distribuição de procura de alimento da Cagarra ao longo do período de reprodução e através dos anos? (2) Estarão os actuais limites (da mIBA e MPA das Berlengas) a proteger todas as importantes áreas de procura de alimento desta espécie? Para responder a estas questões fixaram-se dispositivos de GPS (Global Positioning System) nas penas do dorso dasaves para identificar as áreas de procura de alimento usadas pela espécie. Modelos de distribuição de espécies (MaxEnt) foram realizados usando informação de rastreamento e dados ambientais de forma a entender que variáveis ambientais desencadeiam a distribuição de procura de alimento da espécie. Para avaliar a adequabilidade dos limites das actuais mIBA e MPA das Berlengas usou-se o software Zonation, que pode ser usado para o delineamento e avaliação de Áreas Marinhas Protegidas, produzindo diferentes cenários dependendo das especificações das prioridades de conservação. Os resultados demonstraram diferentes padrões de procura de alimento em 2010 e 2012 comparativamente com os anos de 2011 e 2013; e também diferenças nas características das viagens, com viagens mais perto da colónia nos períodos de alimentação das crias. Estas diferenças anuais podem estar relacionadas com a variação climática, como reflectido pelo índice NAO (North Atlantic Oscillation), que mostra valores de índice positivos mais altos em 2012 (considerando o período de tempo de estudo) e valores de índice negativos mais baixos em 2010. Durante o período de alimentação das crias, as aves mostraram um comportamento de procura de alimento designado por central-place foraging, como consequência da constante necessidade de voltar para a colónia para alimentar as crias. Portanto, áreas na periferia da colonia são mais propensas a ser usadas durante o período de alimentação das crias do que durante os períodos de incubação e antes da postura do ovo. De forma geral, as aves exploraram sobretudo áreas produtivas sobre a plataforma continental nos arredores da colónia e áreas ao longo da costa Portuguesa, assim como áreas produtivas mais distantes perto de bancos e montes submarinos na região do Norte Atlântico. Os resultados permitem-nos concluir que a actual MPA está apenas a proteger 25.9% das áreas de procura de alimento mais relevantes para a Cagarra. Enquanto essas áreas de procura de alimento sobrepõem-se 45.5% com a mIBA das Berlengas. Um valor de sobreposição mais elevado (59.6%) é obtido ao comparar com as novas Áreas Marinhas Protegidas propostas que estão actualmente sob a avaliação do governo Português. A implementação das novas Áreas Marinhas Protegidas iria permitir a protecção das áreas de procura de alimento mais relevantes para a Cagarra. Isto porque a sua implementação iria gerar uma conectividade entre a maioria das áreas a norte e sul da actual MPA das Berlengas, providenciando um corredor ecológico para a Cagarra e outros organismos marinhos. ; Marine ecosystems have been facing an increasing number of threats such as unsustainable exploitation of marine resources (e.g. overfishing), degradation and loss of marine habitats, pollution, invasive species and climate change. A possible way to diminish the impact of such threats is through the establishment of Marine Protected Areas (MPAs), which play an important role in biodiversity conservation and contribute to restock the entire marine environment. However the percentage of ocean that are already protected (2.8%) is alarmingly low considering one of the targets set by the Convention on Biological Diversity (CBD): to protect at least 10% of coastal and marine areas until 2020. Berlengas archipelago surrounding waters have great conservation value due to features that congregate a high marine productivity, allowing the survival and maintenance of several seabird species, some of them endangered (e.g. the Balearic shearwater Puffinus mauritanicus). Although this important area is currently under protection, the boundaries of the Berlengas Marine Protected Area (MPA) do not overlap fully with the Berlengas marine Important Bird Area (mIBA), which was designated based on the areas with great importance to the small range local biodiversity. The present boundaries of the Berlengas MPA were defined with the contribution of tracking information of the most important foraging areas of a wide range seabird top predator, the Cory's shearwater Calonectris diomedea, mostly during the chick-rearing phases of 2005 – 2008. Yet, the boundaries of the Berlengas mIBA and MPA have not been assessed, using tracking information for the whole breeding cycle of this species during several years (in order to take into account inter-annual environmental stochasticity). The aim of this thesis was to use tracking data of a seabird top predator to define boundaries of key foraging grounds and assess their adequacy on the establishment of a network of Marine Protected Areas within Mainland Portugal. More specifically, this work intended to answer the following questions: (1) Which factors (environmental or Human-related) drive the foraging distribution of Cory's shearwater along the breeding period and across years? (2) Are the current boundaries (from both Berlengas mIBA and Berlengas MPA areas) protecting all key foraging grounds of this species? To address these questions Global Positioning System (GPS) tracking devices were attached to the back feathers of Cory's shearwater in order to identify the foraging areas used by this species. Species Distribution Models (SDM; MaxEnt) were performed using foraging tracking data combined with environmentaldata in order to understand which environmental variables trigger the foraging distribution of the species. To better access the adequacy of the current Berlengas mIBA and MPA boundaries it was used the conservation planning software Zonation. This software can be used to design and evaluate Marine Protected Areas by producing different scenarios depending on specification of conservational priorities. Results showed very distinct foraging patterns in 2010 and 2012 comparing with 2011 and 2013 and also distinct foraging trip characteristics, with trips closer to the colony during chick-rearing periods. These annual differences may be related with climatic variation, as reflected by the North Atlantic Oscillation (NAO) index, with the highest positive index value in 2012 (considering our study period) and the lowest negative index value in 2010. During the chick-rearing period, birds showed a typical central-place foraging behaviour, as a consequence of the constant need to return to the colony to feed their chick. Therefore, areas in the vicinity of the colony are more likely to be used during chick-rearing than during pre-laying and incubation periods. Overall, birds mostly exploited productive areas above the continental shelf around the colony and along the Portuguese coast, as well as more distant productivity areas near known banks and seamounts of the north Atlantic region. Results also allowed to conclude that the actual Berlengas MPA is only protecting 25.9% of the most relevant foraging region for Cory's shearwater. While the same foraging region overlapped 45.5% with the Berlengas mIBA. A considerably higher overlapped area (59.6%) was obtained when comparing with new proposed Marine Protected Areas, under evaluation by the Portuguese government. The implementation of these new areas would protect the most relevant foraging areas of Cory's shearwater. This is because the implementation of these new areas would generate connectivity between the main areas north and south of the actual Berlengas MPA, thus providing an ecological corridor for Cory's shearwaters and other marine taxa.
K. Woo, M. Le Vaillant, T. van Nus, and especially A. Wesphal, J. Schultner and I. Dorresteijn, assisted with field work, often under unpleasant conditions. K. Wauthier was instrumental in wrestling the gamma counter into submission. P. Redman and C. Hambly conducted the isotopic analyses. K. Scott and K. Campbell provided the FoxBox. K.H.E. benefited from a Natural Sciences and Engineering Research Council (NSERC) Vanier Scholarship, Association of Canadian Universities for Northern Studies Garfield Weston Northern Studies Award and the Arctic Institute of North America Jennifer Robinson Scholarship. Research support came from Bird Studies Canada/Society of Canadian Ornithologists James Baillie Award, Animal Behavior Society Research Grant, American Ornithologists' Union Research Grant, Frank Chapman Research Grant, the Waterbird Society Nisbet Grant and NSERC Discovery Grants to J.F.H. and W.G.A. Any use of trade names is for descriptive purposes only and does not imply endorsement by the US Government. ; Peer reviewed ; Publisher PDF
Living on the wind-swept Ascension Island, lying as it does in the middle of the Atlantic with Britain 4,000 miles in one direction and the Falklands 4,000 miles in the other, the simple pleasure of an evening spent with a cat on your lap should not be underestimated. And thereby hangs a tale, a remarkable conservation success story that would rid the island of a marauding migrant horde. Rats stowed away on ships and came ashore, and cats were introduced to contain the rodents. Both found easy prey in the abundant seabird colonies and over the next 200 years brought some species to the brink of extinction. At the start of the millennium a plan was conceived to redress the balance. Adapted from the source document.
Funding: This work was supported by the University of Oxford Christopher Welch Scholarship (to J.A.K.); ASAB Undergraduate Project Scholarship (to J.A.K.); UKRI BBSRC scholarship grant number BB/M011224/1 (to J.W. and N.G.); The Queen's College, University of Oxford (to A.L.F.); Junior Research Fellowship at St. John's College, University of Oxford (to O.P.); Merton College, University of Oxford (to T.G.); Mary Griffiths Award (to T.G.); BBSRC David Phillips Fellowship grant numbers BB/G023913/1 and BB/ G023913/2 (to C.R.); and Jesus College, University of Oxford (to G.K.T.). This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 682501) (to G.K.T.) ; Dynamic soaring harvests energy from a spatiotemporal wind gradient, allowing albatrosses to glide over vast distances. However, its use is challenging to demonstrate empirically and has yet to be confirmed in other seabirds. Here, we investigate how flap-gliding Manx shearwaters optimize their flight for dynamic soaring. We do so by deriving a new metric, the horizontal wind effectiveness, that quantifies how effectively flight harvests energy from a shear layer. We evaluate this metric empirically for fine-scale trajectories reconstructed from bird-borne video data using a simplified flight dynamics model. We find that the birds' undulations are phased with their horizontal turning to optimize energy harvesting. We also assess the opportunity for energy harvesting in long-range, GPS-logged foraging trajectories and find that Manx shearwaters optimize their flight to increase the opportunity for dynamic soaring during favorable wind conditions. Our results show how small-scale dynamic soaring affects large-scale Manx shearwater distribution at sea. ; Publisher PDF ; Peer reviewed
