Impacto ecológico, comportamental e fisiológico da bioinvasão sobre populações nativas: o caso do siri invasor Charybdis hellerii
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Data
2016-01-26
Autores
Oliveira, Diogo Nunes de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Processos ecológicos como competição e predação tem o potencial de regular populações, influenciando no funcionamento do ecossistema por intermédio da partição de recursos e perda de espécies. A adição de espécies exóticas em teias tróficas podem alterar esses processos ecológicos e provocar efeitos em cascata. Em um estudo pioneiro, avaliamos por uma perspectiva multidisciplinar, os impactos da introdução de uma espécie de siri asiática na costa oeste do Atlântico. Para isso, aspectos populacionais, ecológicos, fisiológicos e comportamentais foram avaliados em ambiente natural e através de experimentação em laboratório. Nossos resultados revelaram que a espécie de siri invasora Charybdis hellerii está estabelecida na litoral do estado de São Paulo, é um competidor vigoroso, disputando recursos com seis espécies de decápodes nativos, e um predador eficiente, de hábito onívoro, que pode elevar a pressão predatória sobre quatro grupos de presas, três consideradas ‘engenheiros do ecossistema’. As análises comportamental e fisiológica revelaram ainda que a espécie invasora e a nativa Cronius ruber são mais ativas, realizam mais interações comportamentais intra e interespecífica, tendem a dominar a região do entremarés inferior em costões rochosos e que ambas disputam diretamente as mesmas tocas e os mesmos alimentos quando estão no mesmo ambiente. Dessa forma, o aumento populacional da espécie invasora pode elevar a pressão competitiva sobre C. ruber, aumentando também a chance de exclusão competitiva. Se essa exclusão ocorrer e a pressão seletiva do ambiente for elevada, pode não haver tempo hábil suficiente para que mecanismos comportamentais e fisiológicos se desenvolvam permitindo a adaptação da espécie nativa à um novo habitat. Ocorrendo isso, essa espécie poderá entrar em processo de extinção local. Nossos dados suportam a hipótese de que a introdução de C. hellerii no litoral paulista e sua adição nas teias tróficas locais pode elevar a pressão predatória e competitiva, modificando as interações tróficas, a estrutura das comunidades e sendo potencialmente danosa ao equilíbrio do ecossistema.
Ecological processes, such as predation and competition, have the potential to regulate populations, influencing the functioning of the ecosystem through resources partition and loss of species. The addition of alien species into food webs may change these ecological processes and cause cascading effects. In a pioneering study, the impact of the introduction of a species of Asian crab on the Atlantic west coast was evaluated by a multidisciplinary perspective. For this, population, ecological, physiological, and behavioral aspects were evaluated in natural environment and in laboratory experimentation. The results revealed that the species of invasive crab Charybdis hellerii is established on the coast of São Paulo State. This species is a vigorous competitor, competing for resources with six decapod native species, and an efficient predator with omnivorous habit, which can raise the predatory pressure on four prey groups, three of them considered 'ecosystem engineers'. Behavioral and physiological analysis also showed that invasive species and native Cronius ruber are more active, performing more intra and interspecific behavioral interactions. These species tend to dominate the region of the lower intertidal on rocky shores and both compete directly for the same burrow and food when they are in the same environment. Thus, the population growth of invasive species may increase the competitive pressure on C. ruber, also increasing the risk of competitive exclusion. If this exclusion occurs and environmental selective pressure is high, it may not have enough time for developing behavioral and physiological mechanisms that allow the adaptation of native species to a new habitat. This occurring, this species can get into a local extinction process. Our data support the hypothesis that the introduction of C. hellerii on the São Paulo State coast and the addition in local food webs may raise the predatory and competitive pressure by modifying trophic interactions, community structure and are also potentially harmful to the balance of the ecosystem.
Ecological processes, such as predation and competition, have the potential to regulate populations, influencing the functioning of the ecosystem through resources partition and loss of species. The addition of alien species into food webs may change these ecological processes and cause cascading effects. In a pioneering study, the impact of the introduction of a species of Asian crab on the Atlantic west coast was evaluated by a multidisciplinary perspective. For this, population, ecological, physiological, and behavioral aspects were evaluated in natural environment and in laboratory experimentation. The results revealed that the species of invasive crab Charybdis hellerii is established on the coast of São Paulo State. This species is a vigorous competitor, competing for resources with six decapod native species, and an efficient predator with omnivorous habit, which can raise the predatory pressure on four prey groups, three of them considered 'ecosystem engineers'. Behavioral and physiological analysis also showed that invasive species and native Cronius ruber are more active, performing more intra and interspecific behavioral interactions. These species tend to dominate the region of the lower intertidal on rocky shores and both compete directly for the same burrow and food when they are in the same environment. Thus, the population growth of invasive species may increase the competitive pressure on C. ruber, also increasing the risk of competitive exclusion. If this exclusion occurs and environmental selective pressure is high, it may not have enough time for developing behavioral and physiological mechanisms that allow the adaptation of native species to a new habitat. This occurring, this species can get into a local extinction process. Our data support the hypothesis that the introduction of C. hellerii on the São Paulo State coast and the addition in local food webs may raise the predatory and competitive pressure by modifying trophic interactions, community structure and are also potentially harmful to the balance of the ecosystem.
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Palavras-chave
Ecologia Trófica, Trophic Ecology, Competição, Predação, Adição de espécie, Substituição de espécie, Competition, Predation, Addition of species, Species substitution