Distribution and suitable habitat of the cold-water corals Lophelia pertusa, Paragorgia arborea, and Primnoa resedaeformis on the Norwegian continental shelf

Cold-water corals are habitat-forming species that are also classified as indicators of vulnerable marine ecosystems (VMEs) due to the threat of various anthropogenic impacts, e.g., fisheries and oil/mineral exploration. To best protect VMEs, knowledge of their habitat requirements and distribution is essential. However, comprehensive sampling of the deep sea is difficult due to access and cost constraints, so species distribution modeling (SDM) is often used to predict overall distributions and ecological preferences of species based on limited data. We used Maximum Entropy (Maxent) modeling to predict the probability of presence of the reef-building scleractinian Lophelia pertusa and the octocorals Paragorgia arborea and Primnoa resedaeformis using a total of 2149 coral presence points and 15 environmental predictor variables. The environmental variables used in the analysis were processed to 176 m resolution and included bathymetry, depth, geomorphometric characteristics [slope, aspect, and bathymetric position index (BPI)], oceanography (temperature, salinity, current directions, and speed), surface chlorophyll a concentration, sediment type, and marine landscape type. Comparing presence points with environmental data showed that the temperature and depth range for Lophelia was narrower compared to the gorgonians, and it occurred in shallower, warmer water. Observations showed that Lophelia had a broad, bimodal response to Broad BPI, while the predicted model indicated a more narrow response. Paragorgia tolerated the greatest range of sloping according to the model. All three species were observed with a bimodal pattern along a wide range of mean current speed, while the models indicated a high response to faster current speed. Jackknife tests showed that sediment type was an important predictor for gorgonian corals, while BPI and minimum temperature were more important for Lophelia. The spatial precision of the models could be further increased by applying environmental layers with a higher and uniform spatial resolution. The predicted distribution of corals and their relation to environmental variables provides an important background for prioritizing areas for detailed mapping surveys and will aid in the conservation efforts for these VMEs in Norwegian waters and beyond.publishedVersio

Environmental drivers and the distribution of cold-water corals in the global ocean

Species distribution models (SDMs) are useful tools for describing and predicting the distribution of marine species in data-limited environments. Outputs from SDMs have been used to identify areas for spatial management, analyzing trawl closures, quantitatively measuring the risk of bottom trawling, and evaluating protected areas for improving conservation and management. Cold-water corals are globally distributed habitat-forming organisms that are vulnerable to anthropogenic impacts and climate change, but data deficiency remains an ongoing issue for the effective spatial management of these important ecosystem engineers. In this study, we constructed 11 environmental seabed variables at 500 m resolution based on the latest multi-depth global datasets and high-resolution bathymetry. An ensemble species distribution modeling method was used to predict the global habitat suitability for 10 widespread cold-water coral species, namely, 6 Scleractinian framework-forming species and 4 large gorgonian species. Temperature, depth, salinity, terrain ruggedness index, carbonate saturation state, and chlorophyll were the most important factors in determining the global distributions of these species. The Scleractinian Madrepora oculata showed the widest niche breadth, while most other species demonstrated somewhat limited niche breadth. The shallowest study species, Oculina varicosa, had the most distinctive niche of the group. The model outputs from this study represent the highest-resolution global predictions for these species to date and are valuable in aiding the management, conservation, and continued research into cold-water coral species

Driving forces in the distributions of the three most common deep-water coral species in Norway: Lophelia pertusa, Paragorgia arborea, and Primnoa resedaeformis

Postponed access: the file will be accessible after 2018-10-16This thesis explores a set of environmental variables may be used to predict the spatial distribution of the three most common cold-water coral (CWC) species in Norway: Lophelia pertusa, Paragorgia arborea, and Primnoa resedaeformis. CWCs are important biogenic habitats that provide substrate and living space for a variety of deep-sea sessile organisms and commercially important fish, but are threatened by various anthropogenic impacts (e.g. bottom trawling, petroleum exploration and mineral mining), leading to increased efforts to appraise and protect them. Deep-sea exploration is difficult due to cost, time and access constraints, so in order to target protection efforts, species distribution models (SDM) can be created to find areas with the highest probability of species presence. The Maximum Entropy (Maxent) 3.4.1 program was used on CWC presence data and several environmental variable layers covering the Norwegian continental shelf from the southern end of Norway to Svalbard. Data on CWC presence positions from MAREANO video records for all three species together with the IMR Lophelia Reef Database with additional Lophelia presence points were used. The environmental variables were: depth and terrain proxies from a bathymetry layer (processed to 176 x 176m resolution) from EMODnet, oceanographic variables from the Norkyst-800 model, surface chlorophyll a concentration from the Ocean Biology Processing Group in NASA, and sediment and marine landscape type as defined by NGU. Data was prepared and visualized in ArcMap 10.5.1 and environmental characteristics at CWC presence points were summarized in Excel prior to modeling. Maxent produced SDMs that indicated high probability of presence especially on the continental margin and along the Norwegian coast and near fjords. Jackknife tests showed that sediment was particularly important for the gorgonian corals, while chlorophyll a uniquely predicted well for Lophelia. Depth, mean current speed, marine landscape, and slope were important individual indicators of presence for all. The hope is that information gained from the modeled distributions and predictor variables used will help conservation efforts for Lophelia, Paragorgia, and Primnoa.Master's Thesis in BiologyBIO39

Predicting the Distribution of Indicator Taxa of Vulnerable Marine Ecosystems in the Arctic and Sub-arctic Waters of the Nordic Seas

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Species distribution modelling to support marine conservation planning

This thesis explores some important practical considerations concerning the use of species distribution models in marine conservation planning. Using geo-referenced gorgonian distribution data, together with explanatory environmental variables, predictive models have been used to map the spatial distribution of suitable gorgonian (sea fan) habitat in two study sites; Hatton Bank, in the Northeast Atlantic, and Lyme Bay on the south coast of Devon. Generalized Linear Models (GLMs), Generalized Additive Models (GAMs) and a Maximum Entropy (Maxent) model have been used to support critical investigation into important model considerations that have received inadequate attention in the marine environment. The influence of environmental data resolution on model performance has been explored with specific reference to available datasets in the nearshore and offshore environments. The transferability of deep-sea models has been similarly appraised, with recommendations as to the appropriate use of transferred models. Investigating these practical issues will allow managers to make informed decisions with respect to the best and most appropriate use of existing data. This study has also used novel approaches and investigated their suitability for marine conservation planning, including the use of model classification error in the spatial prioritisation of monitoring sites, and the adaptation of an existing presence-only modelling method to include absence data. Together, these studies contribute both practical recommendations for marine conservation planning and novel applications within the wider species distribution modelling discipline, and consider the implications of these developments for managers, to ensure the ongoing improvement and development of models to support conservation planning

Species distribution models for three deep-sea coral and sponge taxa in the Southern California Bight

Deep-Sea Coral and Sponge (DSCS) species are signature taxa of deep-water habitats, however understanding the ecological mechanisms that drive their geographic distributions can be difficult to uncover due to the challenges of surveying deep-water ecosystems. A recent study on benthic assemblages in Southern California revealed statistical associations between several DSCS and demersal fishes, many of which are important to management agencies due to commercial or conservation concerns. Maps that predict where these DSCS may occur are needed for the management and protection of these DSCS taxa and the fauna that rely on them for habitat. In this thesis, I develop predictive models and maps for three DSCS in the Southern California Bight, Antipathes dendochristos, Plumarella longispina, and an unidentified Porifera sponge. Two of the taxa, P. longispina and Porifera have been identified to be associated with young-of-the-year rockfish in a previous study. Predictive maps were created using species distribution models developed with habitat-related variables (e.g. food availability, depth, and bathymetry). Generalized Additive Models (GAMs) were created using the best practices for developing DSCS species distribution models, which includes accounting for spatial auto-correlation and model uncertainty. I provide a comparison of how these model results differ from the results of a commonly used modeling approach, Maxent, that relies on presence-only data. Both GAMs and Maxent models performed well when predicting known occurrences, but the variables deemed most important in those models differed. Predictions using GAMs found that all three taxa were distributed in patches across the study region and that the covariates that predicted species distributions were similar between the three taxa. Specifically, species distributions primarily relied on depth, northern currents, and eastern currents. Maxent predictions were much more constrained throughout the study area, with high suitability found mostly on the fringes of the islands off the coast, and covariates relationships were more variable between species. When the GAMs were constrained to the areas where the model had low uncertainty (Bayesian credible interval ranges \u3c 0.25), the predicted species distributions were more similar between the two modeling methods. High probability of DSCS occurrence exist both inside and outside the Channel Islands National Marine Sanctuary (CINMS), with large areas occurring beyond sanctuary boundaries, mostly north of Santa Barbara Island, around Santa Catalina and San Clemente Islands, and along the coast near San Diego. These areas may be important for future explorations and conservation considerations

Islands in the mud: The South Texas banks provide crucial mesophotic habitat for coral communities

On the continental shelf off the coast of South Texas lie a series of natural hard-bottom structures (rocky outcrops and relic coral-algal reefs) known as the South Texas Banks (STB), which provide critical habitat for benthic organisms and pelagic fish. The depth of the banks, a persistent nepheloid layer, and strong currents have resulted in few studies that provide quantitative biodiversity data on the STB. Using a remotely operated vehicle (ROV), video surveys were conducted to quantitatively describe the mesophotic coral communities and assess habitat suitability of five STB: North Hospital, Hospital, Southern, Big Adam, and Mysterious Banks. Each of these STB have significantly different benthic communites, with coral communities composed primarily of antipatharians and octocorals. Big Adam Bank had the lowest biodiversity and the least coral cover. Mysterious Bank had abundant antipatharians, specifically Stichopathes spp., but low biodiversity overall. Hospital Bank had low coral diversity that was offset by high diversity in sponges and other invertebrate species. North Hospital and Southern Banks had abundant and diverse populations of coral species, including scleractinians, and other benthic invertebrates. These data indicate that the STB are crucial islands of biodiversity in an area with few suitable areas for coral reef species. In addition, predictive modelling of habitat suitability provided valuable estimates on the potential distribution of key benthic community members, such as scleractinians and antipatharians, throughout the entire areas of the five banks assessed

Modeling the suitable habitat of a structural red gorgonian species in the Mediterranean/east Atlantic regions predicts a wider distribution than previously known

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Univerdade do Algarve, 2015Understand how the distribution of deep-sea species is shaped by environment is a challenge for ecologists, given the difficulty of sampling at these locations. Paramuricea clavata is a long-lived species that inhabits the Mediterranean coralligenous assemblages. Its known distribution was so far described as being restricted to Mediterranean Sea, however, new populations were found in the neighboring Atlantic Ocean, suggesting a wider distribution. BRT is a modeling technique that uses algorithms to describe the relation between environmental and presence data, in order to assess species distribution. This method has been applied to ecological studies, showing good accuracy in predicting suitable habitats, since it copes well with the major problems associated with niche modeling. We use BRT to describe the suitable habitat of Paramuricea clavata by determining the variables that limit its distribution, and the species’ tolerance range for these variables. Our results accurately revealed that the suitable habitat is mainly characterized by complex bottom topography (represented by slope) and temperature, presenting a wide range for the first variable (> 0.3⁰) and a well-defined range for the second (12.3 to 26.5⁰C). In addition to the previous known distribution, new potential sites of occurrence were revealed in the Mediterranean Sea, along the coast of Morocco, Algeria, Tunisia and Strait of Sicily, and on the Atlantic coasts between Morocco and southwest Iberia. With this study we were able to describe, for the first time, the ecological niche and potential global distribution of this important structuring species. Moreover, our results contribute to the achievement of future studies of monitoring and conservation of benthic communities in poorly-sampled areas. With the predicted climate change for Mediterranean, the occurrence of mortality events in benthic communities will continue, especially to those found in shallower areas, putting P. clavata at risk.O clima tem um papel fundamental na forma como molda a distribuição global dos organismos, sendo por isso importante conhecer e compreender os limites de tolerância dos mesmos a variações ambientais. Devido à dificuldade de amostragem em ecossistemas profundos, existe ainda uma grande lacuna no que diz respeito aos factores que controlam a distribuição das espécies que neles habitam, nomeadamente as comunidades bentónicas. O Mediterrâneo é um ecossistema que apresenta características muito particulares, abrigando uma vasta diversidade de organismos essencialmente associados às comunidades coralígenas. A Paramuricea clavata é uma das espécies estruturantes mais importantes destas comunidades, tendo um papel muito importante no funcionamento e manutenção do ecossistema. Nos últimos anos, o aumento da temperatura observado no Mediterrâneo tem provocado eventos de mortalidade massiva junto das comunidades bentónicas, levando à perda de populações desta gorgónia. A distribuição conhecida desta espécie era até hoje restrita ao Mediterrâneo, principalmente na zona Norte. Contudo, novas populações foram encontradas no Atlântico adjacente, junto a costa sul e oeste de Portugal e no mar Alboran, indicando uma distribuição mais ampla. Boosted Regression Tress (BRT) é um método de modelação recentemente aplicada na área da ecologia, que permite relacionar dados ambientais com dados de presença, possibilitando a descrição de padrões de distribuição para as espécies. Este método usa algoritmos que aprendem a relação existente entre os dados tipos de dados, permitindo a descrição do seu padrão. BRT resulta da junção de dois algoritmos, árvores de regressão e agregação, o que permite que o modelo final seja construído tendo em conta as interações existentes entre os dados. A flexibilidade do BRT permite contornar os principais problemas associados à modelação de dados ecológicos tais como: 1) capacidade de lidar com diferentes tipos de dados; 2) minimização da perda de função que ocorre devido à tendência de amostragem (sampling bias), existência de locais na área de estudo com maior numero de amostras que outros; 3) é dos métodos menos afetados pela resolução dos dados; e 4) reduz o sobre-ajuste do modelo aos dados da amostra (overfitting), por considerar todas as possíveis combinações destes. Por ser uma técnica que tem revelado boa capacidade de previsão da distribuição, nós utilizamos o BRT para descrever o habitat adequado para a P. clavata. Deste modo, determinámos quais as variáveis mais relevantes para descrição da distribuição desta espécie e quais os seus limites de tolerância. O método mostrou-se eficaz, apresentado um excelente poder preditivo (AUC: 0.98; TSS: 0.96; sensibilidade: 0.98, especificidade: 0.98). O habitat adequado para esta gorgónia é caracterizado por uma topografia de fundo complexa, elevada produtividade e hidrodinamismo de moderado a forte. Os nossos resultados revelaram a topografia do fundo, representada pelo declive, como sendo a variável mais importante para a caracterização do habitat desta espécie, apresentando uma contribuição de 21.5% e um intervalo de tolerância sem limite máximo, > 0.3⁰. Esta variável é um bom indicador da dinâmica que ocorre no fundo, sendo que elevações topográficas estão normalmente associadas a alterações no padrão das correntes, e a zonas de maior produtividade. A Temperatura tem também um papel muito importante (contribuição de 19%), contudo, o intervalo de tolerância é bastante restrito (12.3 a 26.5⁰C), limitando assim a sua área de distribuição. Através deste modelo, verificámos também que, apesar dos nossos dados de presença ocorrerem entre os 15 e 100 m de profundidade, esta consegue atingir os 200 m. Este facto é interessante, visto que a partir de uma determinada profundidade as perturbações ocorridas à superfície não se fazem sentir com tanta intensidade. Neste sentido, a existência de populações profundas pode ser um indicador de zonas de refúgio. A distribuição da espécie ocorre numa estreita linha da costa, ao longo do Mediterrâneo e Atlântico adjacente, e também em ilhas e outras em elevações topográfica do fundo, como montes e bancos submarinos. Para além dos novos locais de presença ocorridos no Atlântico e mar Alboran, o nosso modelo prevê uma boa probabilidade de ocorrência para a região sul do Mediterrâneo, nomeadamente ao longo da costa de Marrocos, Argélia e costa noroeste da Tunísia. Para o Atlântico, a área entre Agadir, Marrocos, e a costa sudoeste da Península Ibérica revela também a possibilidade de ocorrência desta gorgónia. Tendo em conta que se tratam de regiões pouco estudadas, os nossos dados sugerem estas áreas como potenciais alvos para estudos futuros de monitorização e conservação destes habitats. Com as alterações climáticas previstas para o Mediterrâneo, há uma forte possibilidade de ocorrer perda de grande parte das populações da espécie, especialmente das que habitam zonas menos profundas