Pelo menos duas décadas de invasão de Isognomon bicolor no litoral sudeste do Brasil: a regulação top-down de suas populações já seria possível?
Data
2019-07-04
Autores
Santos, Guilherme Lacerda dos 
Santos, Leticia Gevaerd Motta dos
Bianchini, Gabriel Victor
Orientadores
Ignacio, Barbara Lage
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Os costões rochosos são ecossistemas complexos, pois abrigam uma
enorme diversidade de organismos que são importantes ecologicamente para o
ambiente e economicamente para os seres humanos. São ambientes que estão
sujeitos à ocorrência de bioinvasão, um fenômeno causado pela introdução
acidental ou não, de uma espécie em um habitat não compreendido na
distribuição geográfica natural desta espécie. Essa invasão pode causar um
desequilíbrio no local ao qual foi introduzido, podendo levar os organismos nativos
e o próprio ambiente a se adaptarem às novas condições. Nas últimas décadas, o
bivalve invasor Isognomon bicolor se estabeleceu em costões do litoral sudeste
do Brasil, sendo considerado então uma espécie relativamente nova nesse local.
Sua densidade populacional variou fortemente neste curto período, da dominância
a baixíssimo recobrimento em condição de colapso populacional e atual fase de
aparente recuperação populacional. Este estudo realizou dois experimentos e
avaliou a atual intensidade de predação dessa espécie e possíveis alterações ao
longo desses anos (Ingham & Zischke, 1977; López et al. 2010), considerando
avaliar a possibilidade de regulação populacional top-down para I. bicolor.
Considerou-se os predadores Stramonita haemastoma e Trachypollia nodulosa e
constatou-se o baixíssimo consumo da espécie introduzida. A preferência
alimentar se deu em favor da espécie de presa nativa Brachidontes solisianus. A
espécie nativa é comum e bastante abundante no Brasil, e tem tamanho médio
menor do que a espécie introduzida. Comparativamente, observou-se eficiência
de consumo (tempo de manipulação menor e predação efetiva). Concluiu-se que
a regulação top-down não foi a responsável pela regulação da população de
Isognomon bicolor na região sudeste do Brasil.
The rocky shores are complex ecosystems, as they harbor an enormous diversity of organisms that are ecologically important to the environment and economically to humans. They are environments that are subjected to the occurrence of bioinvasion, a phenomenon caused by the accidental introduction, or not of a species in a habitat not understood in the natural geographic distribution of this species. This invasion can cause an unbalance in the place to which it was introduced, and may lead native organisms and the environment itself to adapt to the new conditions. In the last decades, the invasive bivalve Isognomon bicolor settled in the coast of the southeastern of Brazil, being considered then a relatively new species in that place. Its population density varied strongly in this short period, from dominance to very low coverage in the condition of population collapse and current phase of apparent population recovery. This study carried out two experiments and evaluated the current intensity of predation of this species and possible changes over the years (Ingham & Zischke, 1977; López et al., 2010), considering the possibility of top-down population regulation for I. bicolor. The predators Stramonite haemastoma and Trachypollia nodulosa were considered and the very low consumption of the introduced species was verified. The food preference was in favor of the native prey species Brachidontes solisianus. The native species is common and quite abundant in Brazil, and has a smaller average size than the introduced species. Comparatively, consumption efficiency (time of minor manipulation and effective predation) was observed. It was concluded that the top-down regulation was not responsible for the regulation of the population of Isognomon bicolor in the southeastern region of Brazil.
The rocky shores are complex ecosystems, as they harbor an enormous diversity of organisms that are ecologically important to the environment and economically to humans. They are environments that are subjected to the occurrence of bioinvasion, a phenomenon caused by the accidental introduction, or not of a species in a habitat not understood in the natural geographic distribution of this species. This invasion can cause an unbalance in the place to which it was introduced, and may lead native organisms and the environment itself to adapt to the new conditions. In the last decades, the invasive bivalve Isognomon bicolor settled in the coast of the southeastern of Brazil, being considered then a relatively new species in that place. Its population density varied strongly in this short period, from dominance to very low coverage in the condition of population collapse and current phase of apparent population recovery. This study carried out two experiments and evaluated the current intensity of predation of this species and possible changes over the years (Ingham & Zischke, 1977; López et al., 2010), considering the possibility of top-down population regulation for I. bicolor. The predators Stramonite haemastoma and Trachypollia nodulosa were considered and the very low consumption of the introduced species was verified. The food preference was in favor of the native prey species Brachidontes solisianus. The native species is common and quite abundant in Brazil, and has a smaller average size than the introduced species. Comparatively, consumption efficiency (time of minor manipulation and effective predation) was observed. It was concluded that the top-down regulation was not responsible for the regulation of the population of Isognomon bicolor in the southeastern region of Brazil.
Descrição
Citação
SANTOS, Guilherme Lacerda dos; SANTOS, Leticia Gevaerd Motta dos; BIANCHINI, Gabriel Victor. Pelo menos duas décadas de invasão de Isognomon bicolor no litoral sudeste do Brasil: a regulação top-down de suas populações já seria possível? 2019. 31f. Trabalho de conclusão de curso de graduação (Bacharelado Interdisciplinar em Ciência e Tecnologia do Mar) - Instituto do Mar, Universidade Federal de São Paulo, Santos, 2019.