Mapping multi-species habitat use for marine conservation planning

Tese de Doutoramento, Ciências do Mar (Biologia Marinha)As áreas marinhas protegidas (AMPs) desempenham um papel chave na preservação da biodiversidade e dos habitats, e na gestão sustentável dos recursos naturais. Um desenho representativo, conectado, resiliente e adequado das redes de AMPs requere uma boa compreensão da distribuição das espécies e da sua preferência de habitats. No entanto, um conhecimento detalhado está geralmente concentrado em apenas alguns locais de amostragem e espécies. A presente tese está direcionada para os peixes marinhos em habitats costeiros até os 40 m. A abordagem que foi desenvolvida foca-se no desenho de redes de AMPs planeadas para otimizar benefícios ecológicos. Para esta finalidade, previsões preditivas de um conjunto de variáveis dos peixes foram mapeadas para identificar áreas prioritárias para a conservação de múltiplos espécies e objetivos. A dissertação está organizada em sete capítulos. O capítulo 1 dá uma introdução geral ao estado do conhecimento da ciência das AMPs, modelos de distribuição de espécies (MDEs) e ao ecossistema marinho da área de estudo, que integra duas ilhas vizinhas do arquipélago dos Açores (Nordeste Atlântico). Uma visão geral da rede existente de AMPs e das pescas regionais está descrita. O capítulo conclui com a motivação e objetivos desta dissertação. O capítulo 2 apresenta o método de amostragem para aquisição dos dados de ictiofauna, a seleção das espécies-alvos, e os dados ambientais que foram usados na dissertação. Os principais métodos de MDEs utilizados para a produção de mapas preditivos são explicados em detalhe. Este capítulo é a base metodológica para os seguintes três capítulos. Abundância ou presença-ausência de peixes de recife com diferentes ecologias tróficas são modelados e mapeados no capítulo 3. Os resultados mostram que o ambiente determinou o padrão espacial das espécies estudadas. Por exemplo, a abundância foi sempresuperior na interface entre os principais tipos de habitat: rocha e sediment. As áreas com a presença potencial de espécies individuais foram espalhadas na área de estudo mas mais pequenos para múltiplas espécies de um determinado nível trófico. Estes hotspots de multi-espécies são uma potencial contribuição para o 'efeito de reserva' minimizando a área necessária para a conservação. O capítulo 4 apresenta modelos espaciais para a biomassa desovante e a fecundidade potencial (o número de oócitos das fêmeas matures) de peixes de recife selecionados. As duas medidas mostraram uma distribuição espacial heterogénea por espécie e influenciada pela batimetria, forças oceanográficas e distância à fronteira do habitat. Mapas de fecundidade potencial refinaram os padrões espaciais da biomassa desovante para espécies com um sex-ratio altamente enviesado para os machos. Hotspots reprodutivos de várias espécies são potenciais "habitats fonte" aumentando a produção e exportação de larvas para áreas adjacentes. Como tal, vêm potencialmente apoiar o "efeito de recrutamento" das AMPs. Consequentemente, a sua total proteção deve ser promovida. Diferentes índices de biodiversidade e de vulnerabilidade intrínseca para a pesca são analisados no capítulo 5. A proteção de locais de alta biodiversidade é frequentemente exigida em conservação marinha. No entanto, os resultados mostraram que somente os padrões de biodiversidade podem não representar bem as áreas de maior interesse e necessidade para a conservação. A integração da vulnerabilidade intrínseca para a pesca no planeamento espacial resultou numa identificação mais precisa de sítios prioritários. A combinação de ambos os parâmetros é proposta como uma nova abordagem para apoiar o planeamento espacial marítimo que serve a gestão pesqueira e os objetivos de conservação. O capítulo 6 é uma análise abrangente que combina os mapas preditivos que foram produzidos nos três capítulos anteriores com outras características do habitat e sócio-econômicos. Cenários alternativos da rede de reserva foram produzidos com o software 'Marxan', considerando diferentes alvos de conservação e objetivos. Os resultados demonstraram que a estatística da rede (ex. tamanho, 'rácio da-borda-à-área', e percentagem da linha de costa protegida) e o posicionamento da reserva foram influenciados, principalmente, pelos diferentes níveis de proteção. As diferenças foram menos pronunciadas entre soluções que se focaram na pesca ou na conservação da biodiversidade. As soluções criadas pelo Marxan correspondem parcialmente à atual rede de AMPs. Estas mostram alternativas para a localização e tamanho das áreas protegidas, que podem ser usadas em processos de gestão adaptativa. O capítulo 7 combina a discussão geral dos resultados da dissertação, impactos e possíveis trabalhos futuros. Os resultados evidenciam que as AMPs não podem beneficiar igualmente todas as espécies, portanto, é fundamental incluir informação da ecologia espacial de multi-espécies no seu desenho. Análises de representatividade mostraram que todos os hotspots de multi-espécies são quantitativamente bem integrados na rede existente de AMPs. Porém dada a elevada importância biológica/ecológica e a pequena extensão destes hotspots, os futuros processos de gestão devem promover a proteção de toda a área de hotspots para assegurar o seu funcionamento ecológico. Devido à sua clareza a aplicação de mapas preditivos deve ser uma ferramenta prioritária para a gestão do espaço marítimo, especialmente em situações de escassez de dados, desde que rigorosos critérios de validação sejam aplicados. O enquadramento apresentado é simples, direto e eficiente na identificação de habitats com potencialmente alta abundância, fecundidade, diversidade e vulnerabilidade para a pesca. Propõe-se a integração desta abordagem promissora como um primeiro passo de um múltiplo processo para a identificação de sítios prioritários para a conservação que servem vários objetivos.ABSTRACT: Marine protected areas (MPAs) can play a key role in preserving biodiversity and habitats and in managing the sustainable use of natural resources, including fish stocks. Designing representative, connected, resilient, and adequate MPA networks requires a good understanding of the species’ distribution and habitat preferences. Yet, detailed knowledge is often reduced to a few sampled locations and species. This thesis focuses on marine reef fishes in coastal habitats down to the 40 m isobath. A framework is developed to design MPA networks that optimise ecological benefits. For this purpose, predictive distributions of a set of fish variables are spatialised to identify potential sites of priority for conservation that can serve multiple species and objectives. The thesis is organised in seven chapters. Chapter 1 gives an overall introduction to the state of the art on the science of MPAs, species distribution models (SDMs) and the marine ecosystem of the study area, two neighbouring islands of the Azores archipelago (Northeast Atlantic). It includes an overview of the existing MPA network and regional fisheries. The motivation and objectives of the thesis are outlined. Chapter 2 presents the sampling method to acquire fish data, the selection of individual study species, and the environmental data that are used in the thesis. The main methods and background knowledge for the statistical models used to describe the species-environment relationships and to produce predictive maps are explained in detail, setting the basis for the following three chapters. The occurrence and abundance of reef fishes with different trophic ecologies are modelled and spatialised in chapter 3. Results showed that the environment shapes the spatial distribution patterns of the reef fishes. For instance, the abundance was typically highest at the interface between rock and sediment, highlighting the importance of this main ecotone for subtidal fish assemblages. Individual species were predicted to occur in large parts of the study area but these areas were much smaller if multiple species from the same trophic guild were considered. These multi-species abundance hotspots can be a major potential contribution to the 'reserve effect' of MPAs while minimising the area needed for protection. Chapter 4 presents spatially explicit models for the spawning biomass and the potential fecundity (number of oocytes of mature females) of selected reef fishes. The spatial distribution of both measures was heterogeneous, species-specific and influenced by bathymetry, oceanographic forces and the distance to the habitat edge. Maps of the potential fecundity further refined the spatial patterns of the spawning biomass for species with sex-ratios highly skewed towards males. Multi-species reproductive hotspots were identified and are potential 'source habitats' of increased larvae production and export to adjacent areas. As such, they potentially support the 'recruitment effect' of MPAs and their complete protection should be promoted. Chapter 5 evaluates different indices of biodiversity and vulnerability to fishing of fish assemblages. The protection of high-biodiversity sites is often demanded in marine conservation. Yet, results showed that biodiversity patterns alone may not represent well the areas of higher need for conservation. Integrating the intrinsic vulnerability to fishing in spatial planning resulted in a more precise identification of priority sites. The combination of both parameters is proposed as a novel approach to support marine spatial planning that serves fisheries management and conservation objectives. Chapter 6 is one comprehensive analysis that combines the predictive maps produced in the previous three chapters with additional habitat and socio-economic characteristics. Alternative scenarios for a reserve network are produced with the systematic conservation software 'Marxan' considering different conservation targets and objectives. Results demonstrated that the network statistics (e.g. size, edge-to-area ratio, and percentage of protected coastline) and reserve localisation were mainly influenced by the targeted level of protection. In contrast, differences were less pronounced between solutions that focused either on fisheries aspects or the protection of biodiversity within a given conservation target. The solutions provided by Marxan overlapped only partially with the existing MPA network. They provide potential alternatives for the location and size of protected areas that can be used in adaptive management processes. Chapter 7 combines a general discussion of the thesis results, impacts and possible future work. Results highlight that MPAs may not equally benefit all species, thus it is critical to include information of multi-species spatial ecology in their design. Analyses of representativeness showed that all multi-species hotspots are quantitatively well integrated in the existing MPA network. However, given the high biological/ecological significance and the rather small extent of these hotspots, future adaptive management processes should, possibly, promote the protection of the entire area of the hotspots to ensure their ecological functionality. Because of its clarity the application of predictive species distribution maps should be a principle tool for marine spatial management, especially in data scarce situations, provided that rigorous validation criteria are applied. The presented framework is simple, straightforward and efficient in identifying habitats with potentially high fish abundance, fecundity, biodiversity or vulnerability to fishing. It is proposed to integrate this promising approach as a first step of a manifold process for the identification of priority sites for conservation that serve multiple purposes

Acoustic tag retention of the Mediterranean slipper lobster Scyllarides latus (Latreille, 1802) in the Azores

Moulting, growth and retention of externally attached acoustic tags were studied in ten Mediterranean slipper lobsters, Scyllarides latus (Latreille, 1802). Animals were kept in a cage at 20 m depth in Faial Island, Azores, over a period of nine months. No negative effects of tag attachment on moult or behaviour were detected, but a negative effect on growth cannot be excluded. Moulting was correlated with ambient water temperature and resulted in an increase of approximately 7% in mean size and 17% in mean weight. The results demonstrate that the use of externally attached acoustic transmitters in this species is adequate for medium-term movement studies but not for longer-term annual studies, due to the rate of molting

Evaluating seabed habitat representativeness across a diverse set of marine protected areas on the Mid-Atlantic Ridge

Marine ecosystem-based management requires good spatial information on the distribution of marine species and habitats. Often, such information is limited to a few sampled locations, but modelling techniques can be applied to produce predictive distribution maps. A harmonized broad-scale seabed habitat map was recently produced for the archipelagos of Macaronesia under the EMODnet Seabed Habitats Programme. We use this new information to produce an extent-based evaluation of the representativeness and level of protection conferred by the current set of marine protected areas (MPAs) in the Azores to the variety of benthic marine habitats found in this oceanic region. A more objective assessment of the protection effectively provided to the habitats is obtained by applying a scoring system to the MPAs based on the number of allowed extractive and non-extractive human activities and their potential impact on marine biodiversity and habitats. Results show that Azorean habitats within the MPAs are nearly entirely classified as highly protected. In total, 26 habitats (7 of which are endangered and 2 are rare) have at least 10% of their extent in the Azores EEZ protected by MPAs, but another 29 fail to meet this target (4 on-shelf habitats and 25 deep-sea habitats), highlighting the need to extend current protection of bathyal and abyssal habitats and applying adequate ecological coherence criteria. This approach sets a standard that can be used wherever similar information is available, be it in other European regions or beyond.info:eu-repo/semantics/publishedVersio

Predictive mapping of reproductive fish habitats to aid marine conservation planning

Post-settlement spillover from marine protected areas (MPAs) can support adjacent fished populations and has been subject of many scientific studies. The larval subsidy effect, on the contrary, is more challenging to study and less demonstrated although it, arguably, provides key benefits for fisheries. We modeled and predicted the spatial distribution of fish spawning biomass and fecundity across a temperate insular MPA network (Azores archipelago, Northeast Atlantic) and identified potential single and multi-species reproductive habitats (RHs) in shallow reefs. Reproductive strategies or skewed sex ratios influenced spatial patterns of potential spawning biomass and fecundity. Predicted multi-species RHs covered 5-20% of the studied reef habitat. Given their potentially high reproductive output we argue that such sites should be considered in marine conservation planning to increase chances of achieving fisheries and conservation benefits. Spatial patterns of the reproductive output may function as surrogates for larval subsidy when limited or no larval connectivity information is available and assist in identifying potential larval sources and priority sites for conservation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Supporting Online Material (SOM) for: Impact of contrasting conditions at the North-Western Azores Current on carbon-and N 2fixation rates and the abundance of diazotrophic unicellular cyanobacteria

Supplementary data for Riou et al. 2016 PLos On

Importance of N2-Fixation on the Productivity at the North-Western Azores Current/Front System, and the Abundance of Diazotrophic Unicellular Cyanobacteria

International audienceTo understand the impact of the northwestern Azores Current Front (NW-AzC/AzF) system on HCO 3 −-and N 2-fixation activities and unicellular diazotrophic cyanobacteria (UCYN) distribution , we combined geochemical and biological approaches from the oligotrophic surface to upper mesopelagic waters. N 2-fixation was observed to sustain 45-85% of the HCO 3 −-fix-ation in the picoplanktonic fraction performing 47% of the total C-fixation at the deep chlorophyll maximum north and south of the AzF. N 2-fixation rates as high as 10.9 μmol N m-3 d-1 and surface nitrate δ 15 N as low as 2.7‰ were found in the warm (18-24°C), most saline (36.5-37.0) and least productive waters south of the AzF, where UCYN were the least abundant. However, picoplanktonic UCYN abundances up to 55 cells mL-1 were found at 45-200m depths in the coolest nutrient-rich waters north of the AzF. In this area, N 2-fixation rates up to 4.5 μmol N m-3 d-1 were detected, associated with depth-integrated H 13 CO 3 −-fixa-tion rates at least 50% higher than observed south of the AzF. The numerous eddies generated at the NW-AzC/AzF seem to enhance exchanges of plankton between water masses, as well as vertical and horizontal diapycnal diffusion of nutrients, whose increase probably enhances the growth of diazotrophs and the productivity of C-fixers