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9th International Workshop on Marine Technology (MARTECH), virtual, 16-18 June 2021, Eutrophication risk determination requires a continuous acquisition of nutrient data to establish environmental trends. In the context of the MarRISK project, a portable module has been designed to autonomously measure inorganic nutrients together with other parameters such as temperature and salinity along coastal transects

[Resumen]: El objetivo de este proyecto ha sido investigar y determinar si los machos y las hembras de delfín mular (Tursiops truncatus) presentan un mismo uso de hábitat o si, por el contrario, el área que es utilizada difiere en función del sexo. La población de delfines sobre la que se ha realizado la investigación es una población residente que se encuentra en la Ría de Arousa. Para la realización de esta investigación se ha utilizado la foto-identificación para el reconocimiento de individuos, un sistema de información geográfica (QGIS) para conocer el área de distribución de cada uno de los individuos muestreados y diversos análisis estadísticos que conducirán a la resolución del asunto en cuestión. Los resultados obtenidos han demostrado que tanto los machos como las hembras de delfín mular presentan un mismo uso de hábitat, no habiendo diferencias en función del sexo. Con estos resultados se ha verificado que no existe una segregación espacial en la distribución de los ejemplares en función del sexo, habiendo una predominancia de grupos mixtos. Esto va a implicar que el impacto de las actividades humanas será homogéneo en lo que al sexo de los ejemplares se refiere. [Abstract]: The aim of this project has been to investigate and determine if male and female of bottlenose dolphins (Tursiops truncatus) have the same use of habitat or if, on the contrary, the area they use differs according to sex. The population of dolphins on which the research has been carried out is a resident population that is found in Ría de Arousa. To achieve this research, photo-identification has been used for the recognition of individuals, a geographic information system (QGIS) to know the distribution area of each of the sampled individuals and various statistical analyzes that will lead to the resolution of the matter. The results obtained have shown that both male and female of bottlenose dolphins have the same use of habitat, with no differences based on sex. With these results it has been verified that there is no spatial segregation in the distribution of the specimens according to sex, with a predominance of mixed groups. This will imply that the impact of human activities will be homogeneous in terms of the sex of the specimens. Traballo fin de mestrado (UDC.CIE). Bioloxía mariña. Curso 2021/2022

Studying the ecology of a species requires a comprehensive approach encompassing several techniques aimed at understanding different aspects of their ecology such as distribution and habitat, their role in the ecosystem and interactions with the other species. In a constantly changing world, in which (coastal) marine ecosystems are consistently being impacted by human activities, the improved knowledge on marine top predators ecology is of key importance in order to develop effective conservation measures and management plans. In this regard, this thesis uses different approaches to better understand the ecology of a marine top predator, the short-beaked common dolphin (Delphinus delphis, Linnaeus 1758) in Galician waters, North-West Spain, and explores its conservation needs. To do so, the study combines data collected during 273 days at sea, covering a total distance of 9,417 km between March 2014 and October 2017, with information gathered by several studies conducted in the area in previous years. The data collected over four years contributed to improving our understanding of the environmental, topographic and anthropogenic factors influencing the dolphins distribution, and highlighted the areas entailing the most and least suitable habitats for the species and the areas with a higher degree of overlap with fishing activities. This information was combined with regional fisheries information to build an Ecopath with Ecosim framework to study the role of common dolphins in the ecosystem and its relationships with the other species. Furthermore, the approach provided information about the ecological impacts of fisheries on common dolphins and other cetacean species in the area. Results point out the importance of the continental shelf waters for the species and highlight the species vulnerability to direct and especially indirect impacts caused by fisheries, principally trawling activities. In this regard, the study predicts an important population decrease for common dolphins if fishing effort is increased. An interdisciplinary approach combining distribution and habitat use studies with the analysis of trophic food webs was used to explore the overlap between common dolphins and fisheries and the direct and indirect impacts caused on this cetacean species, providing new information on the indirect effects of fisheries on common dolphins, which will be of great value in the development of effective conservation measures and fishing management plans.

Cetaceans frequently display skin marks which can be caused by diseases, parasites, and interactions among conspecifics and with human activities. For the present study, we used one year of photo-identification data for resident bottlenose dolphins of the Ría de Arousa (NW Spain). The aims of this study were to assess the types of skin marks found on bottlenose dolphins and compare them between adult males and females. Four body sections (anterior, ventral, central, and posterior) were defined to assess the prevalence, abundance, richness, and distribution of the marks. Boat-based surveys were carried out on 65 days between January and October 2017 for a duration of 352 hours, with 218 groups of dolphins observed during 98 hours. A total of 178 individuals were identified, and 21 adult sexed individuals (12 males and 9 females) were used for the analysis. Social-induced marks (tooth-rakes, nicks, and linear marks), skin disorders, and parasitic marks were observed, but none of the individuals showed human-induced injuries. All skin marks, except parasitic marks, were found on all the individuals. The abundance of marks is similar between males (mean ± SD = 130.7 ± 20.7) and females (mean ± SD = 88.3 ± 17.5) (Mann-Whitney, z = 1.53, p > 0.05). The richness in tooth-rakes was significantly higher in males, while the richness in skin disorders was significantly higher in females. Skin mark types were dependent on body section, with the posterior section exhibiting more tooth-rake marks and the anterior section exhibiting more skin disorder marks. The behavioural variation between sexes, with males exhibiting more aggressive and agonistic behaviour than females, may explain the fact that males have a higher incidence of social-induced marks. These results show that the analysis of cetacean skin marks is a research technique that can be efficiently used to assess the health and social behaviour of a population. Os cetáceos exibem, frequentemente, marcas corporais que podem ser causadas por doenças, parasitas e interações intraespecíficas e com atividades humanas. Neste estudo, foi usado um ano de dados de identificação fotográfica de golfinhos roazes residentes na Ría de Arousa (NW Espanha). Os objetivos deste estudo foram avaliar os tipos de marcas corporais encontrados nos golfinhos roazes e compará-los entre machos e fêmeas adultos. Quatro seções do corpo (anterior, ventral, central e posterior) foram definidas para avaliar a prevalência, abundância, riqueza e distribuição das marcas. Foram realizadas 65 saídas (dias) de barco, entre janeiro e outubro de 2017, num período de 352 horas, com 218 grupos de golfinhos observados durante 98 horas. Foram identificados 178 indivíduos e 21 indivíduos adultos, cujo sexo foi determinado (12 homens e 9 mulheres), foram utilizados para a análise. Observaram-se marcas sociais (arranhões, cortes e marcas lineares), condições de pele (doenças) e marcas causadas por parasitas. Nenhum dos indivíduos apresentou marcas induzidas por humanos. Todas as marcas corporais, exceto marcas causadas por parasitas, foram encontradas em todos os indivíduos. A abundância de marcas foi maior nos machos (média ± DP = 130,7 ± 20,7) do que nas fêmeas (média ± DP = 88,3 ± 17,5). A riqueza em arranhões foi significativamente maior nos machos, enquanto a riqueza em marcas de doenças de pele foi significativamente maior nas fêmeas. Os tipos de marcas de corporais dependiam da secção do corpo, com a secção posterior a exibir mais marcas de arranhões e a seção anterior mais marcas de doenças. As diferenças de comportamento entre os sexos, com os comportamentos mais agressivos e agonistas dos machos, em comparação com as fêmeas, podem explicar o facto de os machos apresentarem uma maior incidência de marcas induzidas por interações sociais. Estes resultados mostram que a análise das marcas corporais em cetáceos é uma técnica de investigação que pode ser usada para avaliar a saúde e o comportamento social de uma população. Mestrado em Biologia Marinha Aplicada

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Studying the ecology of cetaceans living under the pressure of anthropogenic activities is essential for their conservation. Yet, there is a paucity of information on cetaceans and shellfish farming. Using a long-term and year-round dataset, this study investigates the ecology and the behaviour of a coastal cetacean, the bottlenose dolphin (Tursiops truncatus), in an important area for shellfish farming (Ría de Arousa, North-West Spain). A resident population of bottlenose dolphins was present year-round in this area. Their seasonal abundance varied from 56 to 144 individuals and their apparent survival was high. Of the investigated environmental factors, depth and shellfish farms were influencing dolphins habitat use, and chlorophyll-a and dissolved oxygen were influencing their spatio-temporal aggregation patterns. Foraging behaviour was mainly determined by the sea surface temperature, time of the day, and whether the dolphins were foraging within shellfish farm areas. Dolphins were predicted to be more likely found foraging inside these areas than outside (57% vs. 43%). Findings of this study also revealed variation in foraging behaviour among dolphins, with some individuals foraging more frequently than others within the shellfish farms. In turn, individuals that frequently foraged within shellfish farms had weaker associations compared to others. This study generates key insights into the ecology and the behaviour of a coastal cetacean living under the pressure of the shellfish farming industry. It further provides valuable information on conservation priorities for coastal cetaceans living under such pressures as well as regulations for the shellfish farming industry., L'étude de l'écologie des cétacés vivant sous la pression d'activités anthropiques est essentielle pour leur conservation. Cependant, il existe peu d'informations sur les cétacés et la conchyliculture. À l'aide d'un ensemble de données collectées à long terme, cette étude examine l'écologie et le comportement d'un cétacé côtier, le grand dauphin (Tursiops truncatus), vivant dans une zone importante pour la conchyliculture (Ría d’Arousa, Nord-Ouest de l'Espagne). Le grand dauphin était présent à l'année dans cette région. Leur abondance saisonnière variait de 56 à 144 individus et leur survie apparente était élevée. Parmi les facteurs environnementaux étudiés, la profondeur et la présence de fermes conchylicoles influaient sur leur utilisation de l’habitat, et la chlorophylle-a et l’oxygène dissous influaient sur leurs modes d’agrégation spatio-temporelle. Leur comportement alimentaire dépendait principalement de la température de la surface de la mer, de l’heure de la journée et du fait que les dauphins s’alimentent dans les zones conchylicoles, les dauphins ayant une probabilité plus élevée de se nourrir à l'intérieur de ces zones, qu'à l'extérieur (57%-43%). Certains individus s’alimentaient plus fréquemment que d'autres autour des fermes conchylicoles. À leur tour, les individus qui se nourrissaient fréquemment autour des fermes avaient des associations plus faibles que les autres. Cette étude génère des informations clés sur l'écologie et le comportement d'un cétacé vivant sous la pression de l'industrie conchylicole, sur les priorités de conservation des cétacés vivant sous de telles pressions, ainsi que sur les réglementations applicables au secteur de la conchyliculture.