A carregar...
Publicação
Single and multiple stressor impacts of climate change and deep-sea mining on the black coral Antipathella wollastoni
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 2.76 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
Os ecossistemas de corais de águas frias (CWC) são particularmente sensíveis aos impactos humanos. As potenciais ameaças colocadas pelas mudanças previstas na química da água do mar relacionadas com o aquecimento dos oceanos (OW) e a acidificação dos oceanos (OA) podem afetar a sua fisiologia (por exemplo, crescimento, respiração) e a sobrevivência das espécies que compõem estes ecossistemas vulneráveis. Além disso, as potenciais atividades de extração mineira em águas profundas irão gerar plumas de sedimentos que poderão afetar os organismos marinhos, particularmente os organismos bentónicos suspensívoros. Projeções climáticas recentes mostram que algumas partes da Dorsal Médio-Atlântica, incluindo os Açores, que são de interesse para as empresas de mineração, deverão sofrer alterações a nível das propriedades das massas de água relacionadas com as alterações climáticas (OW, OA) já em 2040. Portanto, é crucial compreender os efeitos cumulativos das alterações climáticas e das plumas de mineração nos CWC. O coral negro Antipathella wollastoni é um habitante comum das encostas das ilhas dos Açores formando populações densas tipicamente em paredes verticais. Esta espécie apresenta ampla distribuição em profundidade ocorrendo principalmente entre 15 e 520 m, sendo descrita até 1420 m de profundidade. O objetivo desta dissertação foi melhorar a compreensão dos efeitos de estressores ambientais, como temperatura (OW) e pH (OA) e partículas de sulfuretos polimetálicos (PMS) originadas por atividades de mineração em mar profundo, na fisiologia de A. wollastoni. As colónias de coral negro foram recolhidas nas zonas costeiras das ilhas do Faial e Pico, entre os 27 e os 40 m. Sabendo que A. wollastoni pode ser encontrada em maiores profundidades, também testei os efeitos dos estressores em condições hiperbáricas para identificar possíveis alterações fisiológicas entre condições atmosféricas e hiperbáricas. Quatro experiências diferentes foram realizadas simulando (1) os efeitos da exposição aguda a partículas de PMS (10 mg L-1), geradas durante potenciais atividades de mineração e OA, sob pressões hiperbáricas e atmosféricas; (2) os efeitos da exposição aguda a partículas de PMS e OW, sob pressões hiperbáricas e atmosféricas; (3) os efeitos da exposição a médio prazo (9 semanas) ao OW; (4) os efeitos da exposição de curto prazo (3 dias) às partículas de PMS, na fisiologia do A. wollastoni. Além disso, foi realizado um estudo observacional para registar o comportamento dos pólipos de A. wollastoni sob exposição a partículas de PMS. Os efeitos da exposição às partículas de PMS, OA e OW foram avaliados medindo as taxas de respiração, sobrevivência e condição do tecido. Os resultados do estudo confirmaram a hipótese apresentada nesta dissertação de que o estado fisiológico de A. wollastoni é diferentemente afetado por um efeito combinado de estressores. Particularmente, o efeito combinado da exposição às partículas de PMS e do aumento da temperatura é o fator de maior impacto na fisiologia de A. wollastoni. As taxas de respiração do coral negro aumentaram 9 vezes quando expostos às partículas de PMS e ao aumento da temperatura, provavelmente indicando um efeito sinergético desses estressores. Além disso, A. wollastoni, em condições experimentais, parece ser menos sensível ao efeito de condições de baixo pH (OA) do que ao aumento da temperatura (OW). A. wollastoni demonstrou capacidade de ajustar a sua resposta metabólica ao aumento da temperatura, possivelmente indicando uma ampla tolerância térmica. Registos de vídeo mostraram que a exposição às partículas de PMS, como único estressor, teve um impacto severo na condição física de A. wollastoni, com a perda total de tecido após 48h de exposição levando à morte de todos os fragmentos após 72h. Os resultados das experiências realizadas sob diferentes condições hidrostáticas indicaram que A. wollastoni não apresentou alteração nas taxas metabólicas quando exposta a estressores em condições hiperbáricas, em comparação com condições atmosféricas. A ausência de um efeito significativo da pressão hiperbárica na resposta fisiológica de A. wollastoni aponta para o uso adequado desta espécie como proxy experimental para múltiplos impactos de estressores no mar profundo, pelo menos para o intervalo de pressões testadas. Esta pesquisa contribui para ampliar o nosso conhecimento sobre os efeitos das atividades antropogénicas nas comunidades de corais negros e para apresentar informações importantes para apoiar ferramentas de gestão para a criação de normas, diretrizes e programas de monitorização das atividades de mineração em mar profundo como parte do regime regulatório “Mining Code” preparado pela Autoridade Internacional dos Fundos Marinhos (International Seabed Authority, ISA).
ABSTRACT: Cold-water coral (CWC) ecosystems are particularly sensitive to human impacts. Potential threats posed by predicted changes in seawater chemistry related to ocean warming (OW) and ocean acidification (OA) could affect their physiology (e.g. growth, respiration) and survival of the species that compose these vulnerable ecosystems. Moreover, potential deep-sea mining extraction activities will generate sediment plumes expected to impact marine organisms, particularly benthic suspension feeders. Recent projections show that some parts of the Mid-Atlantic Ridge, including the Azores, that are of interest to mining companies are predicted to experience changes in water mass properties related to climate change (OW, OA) as early as 2040. Therefore, it is crucial to understand the cumulative effects of climate change and mining plumes on CWC. The black coral Antipathella wollastoni is a common inhabitant of island slopes in the Azores forming dense populations typically on vertical walls. This species has a wide depth distribution occurring mainly between and 520 m but being described to 1420 m depth. The aim of this dissertation was to improve our understanding of the effects of environmental stressors, such as temperature (OW) and pH (OA) and polymetallic sulphide (PMS) particles originated from deep-sea mining activities, on the physiology of A. wollastoni. Black coral colonies were collected in coastal areas of Faial-Pico Islands, around 27 to 40 m. Knowing that A. wollastoni can be found at higher depths, I also tested the stressor effects under hyperbaric conditions to identify possible physiological changes between atmospheric and hyperbaric conditions. Four different experiments were conducted simulating (1) the effects of acute exposure to PMS particles (10 mg L-1), generated during potential mining activities and OA, under hyperbaric and atmospheric pressures; (2) the effects of acute exposure to PMS particles and OW, under hyperbaric and atmospheric pressures; (3) the effects of medium-term exposure (9 weeks) to OW; (4) the effects of short-term exposure (3 days) to PMS particles, on the physiology of the A. wollastoni. Additionally, an observational study was conducted to record A. wollastoni polyp’s behaviour under PMS particle exposure. The effect of PMS particles exposure, OA and OW were assessed by measuring respiration rates, survival, and tissue condition. Results of the study confirmed the hypothesis put forward in this dissertation that A. wollastoni physiological state is differently affected by a combined effect of stressors. Particularly, the combined effect of PMS particle exposure and increased temperature is the most impactful factor on A. wollastoni physiology. The black coral respiration rates showed an increase by 9 times-fold when exposed to PMS and increased temperature, probably indicating a synergetic effect of these stressors. Also, A. wollastoni, under experimental conditions, seems to be less sensitive to the effect of low pH conditions (OA) than to increased temperature exposure (OW). A. wollastoni showed the ability to adjust its metabolic response to increasing temperatures, possibly indicating a broad thermal tolerance. Video records showed that PMS particles exposure, as a single stressor, had a severe impact on A. wollastoni physical condition, with the total loss of tissue after 48h exposure leading to the death of all fragments after 72h. The results from the experiments performed under different hydrostatic conditions, indicated that A. wollastoni, did not show any change on metabolic rates when exposed to stressors under hyperbaric conditions, when compared with atmospheric conditions. The absence of a significant effect of hyperbaric pressure on the physiological response of A. wollastoni, points out to the suitability of using this species as an experimental proxy for multiple stressor impacts in the deep-sea, at least for the range of pressures tested. This research contributes to broadening our knowledge regarding the effects of anthropogenic activities on black corals communities and to put forward key information to support management tools for the creation of standards, guidelines, and monitoring programs of deep-sea mining activities as part of the International Seabed Authority’s (ISA) Mining Code.
ABSTRACT: Cold-water coral (CWC) ecosystems are particularly sensitive to human impacts. Potential threats posed by predicted changes in seawater chemistry related to ocean warming (OW) and ocean acidification (OA) could affect their physiology (e.g. growth, respiration) and survival of the species that compose these vulnerable ecosystems. Moreover, potential deep-sea mining extraction activities will generate sediment plumes expected to impact marine organisms, particularly benthic suspension feeders. Recent projections show that some parts of the Mid-Atlantic Ridge, including the Azores, that are of interest to mining companies are predicted to experience changes in water mass properties related to climate change (OW, OA) as early as 2040. Therefore, it is crucial to understand the cumulative effects of climate change and mining plumes on CWC. The black coral Antipathella wollastoni is a common inhabitant of island slopes in the Azores forming dense populations typically on vertical walls. This species has a wide depth distribution occurring mainly between and 520 m but being described to 1420 m depth. The aim of this dissertation was to improve our understanding of the effects of environmental stressors, such as temperature (OW) and pH (OA) and polymetallic sulphide (PMS) particles originated from deep-sea mining activities, on the physiology of A. wollastoni. Black coral colonies were collected in coastal areas of Faial-Pico Islands, around 27 to 40 m. Knowing that A. wollastoni can be found at higher depths, I also tested the stressor effects under hyperbaric conditions to identify possible physiological changes between atmospheric and hyperbaric conditions. Four different experiments were conducted simulating (1) the effects of acute exposure to PMS particles (10 mg L-1), generated during potential mining activities and OA, under hyperbaric and atmospheric pressures; (2) the effects of acute exposure to PMS particles and OW, under hyperbaric and atmospheric pressures; (3) the effects of medium-term exposure (9 weeks) to OW; (4) the effects of short-term exposure (3 days) to PMS particles, on the physiology of the A. wollastoni. Additionally, an observational study was conducted to record A. wollastoni polyp’s behaviour under PMS particle exposure. The effect of PMS particles exposure, OA and OW were assessed by measuring respiration rates, survival, and tissue condition. Results of the study confirmed the hypothesis put forward in this dissertation that A. wollastoni physiological state is differently affected by a combined effect of stressors. Particularly, the combined effect of PMS particle exposure and increased temperature is the most impactful factor on A. wollastoni physiology. The black coral respiration rates showed an increase by 9 times-fold when exposed to PMS and increased temperature, probably indicating a synergetic effect of these stressors. Also, A. wollastoni, under experimental conditions, seems to be less sensitive to the effect of low pH conditions (OA) than to increased temperature exposure (OW). A. wollastoni showed the ability to adjust its metabolic response to increasing temperatures, possibly indicating a broad thermal tolerance. Video records showed that PMS particles exposure, as a single stressor, had a severe impact on A. wollastoni physical condition, with the total loss of tissue after 48h exposure leading to the death of all fragments after 72h. The results from the experiments performed under different hydrostatic conditions, indicated that A. wollastoni, did not show any change on metabolic rates when exposed to stressors under hyperbaric conditions, when compared with atmospheric conditions. The absence of a significant effect of hyperbaric pressure on the physiological response of A. wollastoni, points out to the suitability of using this species as an experimental proxy for multiple stressor impacts in the deep-sea, at least for the range of pressures tested. This research contributes to broadening our knowledge regarding the effects of anthropogenic activities on black corals communities and to put forward key information to support management tools for the creation of standards, guidelines, and monitoring programs of deep-sea mining activities as part of the International Seabed Authority’s (ISA) Mining Code.
Descrição
Dissertação de Mestrado, Estudos Integrados dos Oceanos, 11 de outubro de 2024, Universidade dos Açores.
Palavras-chave
Climate change deep-sea mining hyperbaric pressure antipatharians or 21 black corals Antipathella wollastoni ocean acidification ocean warming polymetallic sulphide particles
Contexto Educativo
Citação
ARZENI, Beatriz Gouveia. (2024). "Single and multiple stressor impacts of climate change and deep-sea mining on the black coral Antipathella wollastoni". Horta: Universidade dos Açores, 2024, 75 p. Dissertação de Mestrado em Estudos Integrados dos Oceanos. Disponível em http://hdl.handle.net/10400.3/8915