Meiofauna associada a ilhas orgânicas no Oceano Atlântico Sudoeste
Data
2023-09-27
Autores
Ávila, Ana Karoline Frutuoso de 
Orientadores
Gallucci, Fabiane
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Quedas orgânicas, como carcaças de baleia e parcelas de madeira, têm sido investigadas há muitas décadas no mar profundo. Esses ambientes efêmeros são importantes para o ambiente oligotrófico do mar profundo, abrigando uma densa fauna oportunista e especializada. Vários estudos com foco em macro invertebrados têm se dedicado a descrever e comparar quedas orgânicas, com o intuito de compreender como esses ambientes são colonizados, explorando sua diversidade e os fatores que moldam a estrutura das comunidades. Embora alguns estudos relatem a presença de organismos da meiofauna como parcela significativa da fauna colonizadora de substratos orgânicos, poucos esforços foram empreendidos para aprofundar nossa compreensão da dinâmica de colonização e da composição dessas comunidades em quedas orgânicas. Nesse contexto, a atual dissertação tem por objetivo investigar a meiofauna associada a ossos de baleia e parcelas de madeira experimentalmente implantadas em diferentes profundidades, bem como uma carcaça natural encontrada a 4204 m de profundidade no Oceano Atlântico Sudoeste profundo. Dessa forma, a dissertação foi estruturada em três capítulos, complementados pela introdução ao tema e pelas considerações finais do trabalho. O capítulo 1 tem como enfoque principal a investigação da meiofauna, em particular as assembleias de Nematoda colonizadoras de ossos implantados a 1500 e 3300 metros em diferentes latitudes, e de uma carcaça natural encontrada a 4204 metros, e compará-las às assembleias de Nematoda de outros ambientes de mar profundo. Este capítulo mostra que as assembleias de Nematoda associadas a vértebras de baleia se assemelham àquelas presentes em fontes hidrotermais e locais de exsudações frias. Diferenças entre as carcaças implantadas em diferentes profundidades e também a carcaça natural indicam também que as condições oceanográficas e o tempo de deposição da carcaça no fundo do oceano podem influenciar a composição e a riqueza das assembleias de Nematoda em ilhas orgânicas no mar profundo. A segunda parte da dissertação (Capítulos 2 e 3) amplia a abrangência das investigações sobre a meiofauna em ilhas orgânicas no Oceano Atlântico Sudoeste para uma área mais rasa na região sul da Bacia de Santos, e adiciona o substrato madeira, a fim de ampliar nossa compreensão dos processos de colonização e dispersão da meiofauna nesses ambientes. Assim, o Capítulo 2 tem por objetivo descrever as assembleias de Nematoda colonizadoras de parcelas de madeira e ossos de baleia implantados a 550 metros de profundidade no Oceano Atlântico Sudoeste. As assembleias de Nematoda colonizaram ambos os substratos e apresentaram assembleias com baixa riqueza de gêneros e a dominância de gêneros únicos, compartilhando fauna com outros ambientes quimiossintéticos. Dessa forma, este capítulo apresenta novos resultados que suportam evidências de que ambientes efêmeros e outros ambientes quimiossintéticos amplamente distribuídos podem desempenhar um papel importante na colonização e dispersão de gêneros específicos no mar profundo. Por fim, no Capítulo 3, são apresentadas observações sobre o processo de colonização de ossos de baleia em relação às condições de degradação do substrato. Este capítulo evidencia que tanto as condições de degradação quanto às interações bióticas têm o potencial de influenciar a estrutura da meiofauna em substratos orgânicos. Dessa forma, esta dissertação contribui para conhecimento das estruturas das comunidades colonizadoras de substratos orgânicos, em especial a meiofauna, e sua importância para a diversidade e conectividade no mar profundo. Sugerindo que ilhas orgânicas potencialmente atuem como um importante ambiente intermediário para dispersão e evolução de organismos meiofaunais associados a ambientes quimiossintéticos no mar profundo, particularmente no Oceano Atlântico Sudoeste.
Organic falls, such as whale falls and wood plots, have been investigated for many decades in the deep sea. These ephemeral environments are important to the deep-sea oligotrophic environments, harboring dense opportunistic and specialized fauna. Several studies focusing on macroinvertebrates have described and compared organic falls in order to understand how these environments are colonized, their diversity, and the drivers of community structure. Although some studies report the presence of meiofauna organisms as a significant portion of the colonizing fauna in organic substrates, few studies have been conducted to understand the dynamics of colonization and the composition of these communities in organic falls. This dissertation aims to describe the endofauna communities associated with experimentally deployed whalebone and wood parcels at different depths, as well as those associated with a natural carcass found at 4204 meters depth in the deep Southwest Atlantic Ocean. In this way, the dissertation was structured into three chapters, increased by the general introduction and the final considerations. Chapter 1 investigates the meiofauna, specifically nematodes assemblages that colonizing whalebones deployed at 1500 and 3300 meters at different latitudes, as well as a natural carcass found at 4204 meters. This chapter demonstrates that nematode assemblages associated with whalebones are similar to those present at hydrothermal vents and cold seeps. It also shows that oceanographic conditions and the time of carcass deposition on the ocean floor can influence the composition and richness of nematode assemblages on deep-sea organic islands. The second part of the dissertation (Chapters 2 and 3) extends our investigations into meiofauna on organic falls in the Southwest Atlantic Ocean in a shallower site (i.e., 550m) in the southern region of the Santos Basin, and adds the wood substrate in order to broaden our understanding of colonization and dispersal of meiofauna in these environments. Thus, Chapter 2 aims to describe nematode assemblages colonizing wood and whalebone deployed at a depth of 550 meters in the Southwest Atlantic Ocean. Nematoda assemblages colonized both substrates and presented assemblages with a low richness of genera and the dominance of single genera, resembling fauna with other chemosynthetic environments. Thus, this chapter presents new results that support evidence that ephemeral and other widely distributed chemosynthetic environments may play an important role in the colonization and dispersal of specific genera in the deep sea. Finally, Chapter 3 presents observations regarding the colonization process of whalebone in relation to substrate degradation conditions. This chapter highlights that degradation conditions and biotic interactions have the potential to influence the meiofauna structure in organic substrates. Overall, this dissertation aims to contribute to the understanding of the structure of communities in organic substrates, especially meiofauna communities, and their significance in deep-sea environments in terms of biodiversity and connectivity. Thus, our results consistently support that ephemeral organic falls could potentially serve as an important intermediate environment for the dispersal and evolution of deep-sea nematodes associated with chemosynthetic production in the SW Atlantic Ocean, corroborating previous studies focused on macrofaunal representatives.
Organic falls, such as whale falls and wood plots, have been investigated for many decades in the deep sea. These ephemeral environments are important to the deep-sea oligotrophic environments, harboring dense opportunistic and specialized fauna. Several studies focusing on macroinvertebrates have described and compared organic falls in order to understand how these environments are colonized, their diversity, and the drivers of community structure. Although some studies report the presence of meiofauna organisms as a significant portion of the colonizing fauna in organic substrates, few studies have been conducted to understand the dynamics of colonization and the composition of these communities in organic falls. This dissertation aims to describe the endofauna communities associated with experimentally deployed whalebone and wood parcels at different depths, as well as those associated with a natural carcass found at 4204 meters depth in the deep Southwest Atlantic Ocean. In this way, the dissertation was structured into three chapters, increased by the general introduction and the final considerations. Chapter 1 investigates the meiofauna, specifically nematodes assemblages that colonizing whalebones deployed at 1500 and 3300 meters at different latitudes, as well as a natural carcass found at 4204 meters. This chapter demonstrates that nematode assemblages associated with whalebones are similar to those present at hydrothermal vents and cold seeps. It also shows that oceanographic conditions and the time of carcass deposition on the ocean floor can influence the composition and richness of nematode assemblages on deep-sea organic islands. The second part of the dissertation (Chapters 2 and 3) extends our investigations into meiofauna on organic falls in the Southwest Atlantic Ocean in a shallower site (i.e., 550m) in the southern region of the Santos Basin, and adds the wood substrate in order to broaden our understanding of colonization and dispersal of meiofauna in these environments. Thus, Chapter 2 aims to describe nematode assemblages colonizing wood and whalebone deployed at a depth of 550 meters in the Southwest Atlantic Ocean. Nematoda assemblages colonized both substrates and presented assemblages with a low richness of genera and the dominance of single genera, resembling fauna with other chemosynthetic environments. Thus, this chapter presents new results that support evidence that ephemeral and other widely distributed chemosynthetic environments may play an important role in the colonization and dispersal of specific genera in the deep sea. Finally, Chapter 3 presents observations regarding the colonization process of whalebone in relation to substrate degradation conditions. This chapter highlights that degradation conditions and biotic interactions have the potential to influence the meiofauna structure in organic substrates. Overall, this dissertation aims to contribute to the understanding of the structure of communities in organic substrates, especially meiofauna communities, and their significance in deep-sea environments in terms of biodiversity and connectivity. Thus, our results consistently support that ephemeral organic falls could potentially serve as an important intermediate environment for the dispersal and evolution of deep-sea nematodes associated with chemosynthetic production in the SW Atlantic Ocean, corroborating previous studies focused on macrofaunal representatives.
Descrição
Citação
ÁVILA, Ana Karoline Frutuoso de. Meiofauna associada a ilhas orgânicas no Oceano Atlântico Sudoeste. 2023. 63 f. Dissertação (Mestrado em Biodiversidade Marinha e Costeira) - Universidade Federal de São Paulo, Instituto do Mar, Santos, 2023.