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Os cachalotes (Physeter macrocephalus, Pm) foram extensamente caçados globalmente desde o século XIX, mas a caça comercial parou em 1986 graças à moratória estabelecida pela Comissão Baleeira Internacional (IWC). Esses cetáceos passam grande parte de suas vidas no oceano profundo, alimentando-se principalmente de cefalópodes. O oceano desempenha um papel importante na manutenção do equilíbrio ecológico da Terra. No entanto, ameaças atuais continuam a desafiar a saúde dos oceanos, enquanto os impactos sobre a biodiversidade marinha e as dinâmicas predador-presa ainda são pouco compreendidos. A investigação sobre a dieta dos cachalotes e sobre os cefalópodes oceânicos ao redor dos Açores começaram há várias décadas, inicialmente por meio do estudo do conteúdo estomacal de cachalotes caçados.
Quarenta anos depois, essa investigação passou para outro patamar. Esta tese tem como objetivo obter dados sobre a biodiversidade de cefalópodes do oceano profundo e a ecologia dos cetáceos, utilizando uma abordagem participativa de investigação com amostragem não invasiva. A transição regional da caça para a observação de cetáceos abriu novas oportunidades para envolver atores do turismo na colheita de amostras biológicas. Foram analisados três tipos de amostras para análise molecular. Primeiro, restos de cefalópodes, provavelmente trazidos à superfície por cetáceos, foram coletados e identificados por DNA barcoding, revelando a diversidade local de cefalópodes e fornecendo as primeiras informações sobre a dieta dos cetáceos seus predadores (projeto MONICEPH). Em segundo lugar, o ADN ambiental (eDNA) de amostras fecais de cachalores foi analisado via metabarcoding, enriquecendo consideravelmente as informações sobre a dieta desses predadores. Além disso, foram analisadas também amostras fecais de golfinhos-de-Risso (Grampus griseus, Gg) e de baleias piloto de barbatana curta (Globicephala macrorhynchus, Gma). Por fim, a pele descamada dos cachalotes, coletada junto às amostras fecais, permitiu a análise da região de controle do DNA mitocondrial (MCR) para identificar haplótipos. Como a maioria das amostras de cachalote foi coletada em São Miguel, foram avaliadas as diferenças na distribuição dos haplótipos e na dieta entre o norte e o sul da ilha.
No total, foram registados 34 taxa distintos de cefalópodes, pertencentes a 20 famílias. As 182 amostras de tecido de cefalópodes permitiram determinar 16 taxa, que foram todos identificados também nas amostras fecais, com exceção de um. O metabarcoding utilizando os primers Ceph18S em 36 amostras de Pm, Gg e Gma permitiu identificar 33 taxa de cefalópodes. A amplificação do MCR a partir de 70 amostras fecais e 34 de pele descamada possibilitou a identificação de 90 sequências de MCR atribuídas a 79 cachalotes, revelando quatro haplótipos, incluindo um identificado pela primeira vez a nível global. A distribuição geográfica dos diferentes haplótipos em São Miguel foi heterogênea, embora alguma fidelidade ao local tenha sido observada. Constatou-se que a dieta dos cachalores diferia entre o norte e o sul da ilha de São Miguel, bem como entre machos adultos e fêmeas, mas essas diferenças não foram associadas a haplótipos. Apesar das diferenças metodológicas, a comparação com análises históricas do conteúdo estomacal mostrou similaridade na ocorrência de taxa e nas famílias mais frequentes, embora algumas variações também tenham sido observadas. A sobreposição de onze taxa encontrados nas dietas de Gg e Gma permitiu obter os primeiros resultados para avaliar potenciais fatores que influenciam a competição interespecífica.
Este trabalho avançou o conhecimento sobre a biodiversidade de cefalópodes do oceano profundo por meio de uma abordagem inovadora, utilizando amostragem não invasiva e incorporando ciência participativa para monitorização contínua. Melhorou-se o conhecimento da dieta dos cachalotes e obtiveram-se os primeiros resultados para golfinhos de Risso e baleiaspiloto, que têm nichos ecológicos sobrepostos. Além disso, fornecem-se informações sobre a estrutura populacional e os padrões espaço-temporais dos cachalotes em torno de São Miguel.
Essa abordagem é altamente replicável e prioriza padrões éticos. Os dados resultantes são essenciais para os esforços de conservação e a gestão dos ecossistemas, tendo em conta os desafios oceânicos atuais.
ABSTRACT: Sperm whales (Physeter macrocephalus, Pm) were extensively hunted globally during the industrialization era, but the International Whaling Commission (IWC) ultimately banned commercial whaling. These cetaceans spend much of their lives in the deep ocean to feed mainly on cephalopods. That ecosystem plays an important role in maintaining ecological balance on Earth. However, modern threats continue to challenge ocean health, while the impacts on marine biodiversity and predator-prey dynamics remain poorly understood. Research on sperm whale diet and oceanic cephalopods around the Azores began several decades ago, initially through the study of dead sperm whale stomach contents. Forty years later, this research was further advanced. This thesis focuses on generating deep-ocean cephalopods biodiversity and cetaceans’ ecological data, using a participatory research approach with non-invasive sampling. The regional transition from whaling to whale watching opened new opportunities to involve tourism actors in biological samples collection. Three types of samples were targeted for molecular analysis. First, cephalopod remains, likely brought to the surface by cetacean predators, were collected and identified through DNA barcoding, revealing local cephalopod diversity and gave first information on predator diet (MONICEPH project). Second, environmental DNA (eDNA) from sperm whale faecal samples were analysed via metabarcoding and considerably enriched predator dietary information. Additionally, Risso’s dolphins (Grampus griseus, Gg) and short-finned pilot whales (Globicephala macrorhynchus, Gma) fecal samples were added to the analysis. Finally, samples of sperm whales’ sloughed skin enabled mitochondrial DNA control region (MCR) analysis to identify haplotypes. As most of sperm whales’ samples come from São Miguel, their haplotype distribution and diet differences were assessed between the north and south of the island. In total 34 distinct taxa of cephalopods from 20 families were recorded. The 182 cephalopods tissues allowed to determine 16 cephalopod taxa and they were all encountered in the fecal samples as well, expect for one. Metabarcoding using the Ceph18S primers on 36 samples of Pm, Gg and Gma, allowed to identify 33 cephalopod taxa. MCR amplification from 70 fecal and 34 sloughed skins samples, allowed to determine 90 MCR sequences assigned to 79 sperm whales and revealed four haplotypes, including one globally newly identified. The geographical distribution of the different haplotypes around São Miguel was heterogeneous, though some site fidelity was apparent. Moreover, sperm whale diets differed between the north and the south of São Miguel Island, and between adult males and females, but the differences were not assigned to haplotype. Despite differences in methodology, comparison with historical stomach content analysis showed similarity in taxa occurrence and in most frequent cephalopod families, while some variations were observed as well. Overlap of eleven taxa found in diets of Gg and Gma, allowed to obtain the first results to evaluate potential drivers of interspecies competition. This work advances knowledge of deep-ocean cephalopod biodiversity through an innovative approach, using non-invasive sampling and incorporating participatory science for ongoing monitoring. It improved understanding of sperm whale diet with modern tools and allowed to obtain first results for Risso’s dolphins and pilot whales, which share overlapping ecological niches. Moreover, it informs on sperm whales population structure and spatiotemporal patterns. This approach is highly replicable and prioritizes ethical standards. The resulting data are necessary to continue informing conservation efforts and ecosystem management in the face of ongoing oceanic challenges.
ABSTRACT: Sperm whales (Physeter macrocephalus, Pm) were extensively hunted globally during the industrialization era, but the International Whaling Commission (IWC) ultimately banned commercial whaling. These cetaceans spend much of their lives in the deep ocean to feed mainly on cephalopods. That ecosystem plays an important role in maintaining ecological balance on Earth. However, modern threats continue to challenge ocean health, while the impacts on marine biodiversity and predator-prey dynamics remain poorly understood. Research on sperm whale diet and oceanic cephalopods around the Azores began several decades ago, initially through the study of dead sperm whale stomach contents. Forty years later, this research was further advanced. This thesis focuses on generating deep-ocean cephalopods biodiversity and cetaceans’ ecological data, using a participatory research approach with non-invasive sampling. The regional transition from whaling to whale watching opened new opportunities to involve tourism actors in biological samples collection. Three types of samples were targeted for molecular analysis. First, cephalopod remains, likely brought to the surface by cetacean predators, were collected and identified through DNA barcoding, revealing local cephalopod diversity and gave first information on predator diet (MONICEPH project). Second, environmental DNA (eDNA) from sperm whale faecal samples were analysed via metabarcoding and considerably enriched predator dietary information. Additionally, Risso’s dolphins (Grampus griseus, Gg) and short-finned pilot whales (Globicephala macrorhynchus, Gma) fecal samples were added to the analysis. Finally, samples of sperm whales’ sloughed skin enabled mitochondrial DNA control region (MCR) analysis to identify haplotypes. As most of sperm whales’ samples come from São Miguel, their haplotype distribution and diet differences were assessed between the north and south of the island. In total 34 distinct taxa of cephalopods from 20 families were recorded. The 182 cephalopods tissues allowed to determine 16 cephalopod taxa and they were all encountered in the fecal samples as well, expect for one. Metabarcoding using the Ceph18S primers on 36 samples of Pm, Gg and Gma, allowed to identify 33 cephalopod taxa. MCR amplification from 70 fecal and 34 sloughed skins samples, allowed to determine 90 MCR sequences assigned to 79 sperm whales and revealed four haplotypes, including one globally newly identified. The geographical distribution of the different haplotypes around São Miguel was heterogeneous, though some site fidelity was apparent. Moreover, sperm whale diets differed between the north and the south of São Miguel Island, and between adult males and females, but the differences were not assigned to haplotype. Despite differences in methodology, comparison with historical stomach content analysis showed similarity in taxa occurrence and in most frequent cephalopod families, while some variations were observed as well. Overlap of eleven taxa found in diets of Gg and Gma, allowed to obtain the first results to evaluate potential drivers of interspecies competition. This work advances knowledge of deep-ocean cephalopod biodiversity through an innovative approach, using non-invasive sampling and incorporating participatory science for ongoing monitoring. It improved understanding of sperm whale diet with modern tools and allowed to obtain first results for Risso’s dolphins and pilot whales, which share overlapping ecological niches. Moreover, it informs on sperm whales population structure and spatiotemporal patterns. This approach is highly replicable and prioritizes ethical standards. The resulting data are necessary to continue informing conservation efforts and ecosystem management in the face of ongoing oceanic challenges.
Descrição
Tese de Doutoramento, Biologia, 09 de junho de 2026, Universidade dos Açores.
Palavras-chave
DNA metabarcoding Diet analysis Teuthophagous cetacean Cephalopod Parcipatory science
Contexto Educativo
Citação
SUCIU, Stéphanie R. A. (2025). Ecology of cephalopod/cetacean interactions in the Azores. Ponta Delgada: Universidade dos Açores, 2025. 172 p. Tese de Doutoramento em Biologia. Disponível em http://hdl.handle.net/10400.3/9032