Response of polychaetes to oil spills in natural and defaunated subtropical mangrove sediments from Paranaguá bay (SE Brazil)

Abstract

A short-term short-scale field manipulation experiment was designed to assess the effects of total or partial defaunation, by sediment drying or diesel oil respectively, on polychaete recolonization rates in mangrove sediments of Paranaguá Bay, SE Brazil. After replacement of defaunated cores in the field, disturbed and adjacent undisturbed control sites were subsequently sampled together with adjacent undisturbed control sites on different dates over a 64-day period. Analyses of variance were carried out to test for differences in polychaete populational densities among experimental treatments and sampling dates. Examination of cores impacted by oil showed that most polychaete species kept rather active, quickly reacting to mechanical or light stimuli or moving rapidly. Polychaete recolonization of local mangroves after small-scale disturbance by oil was a fast process, in contrast to that following total defaunation by sediment drying. Rapid recolonization was largely dependent upon the differing mobility of adults of individual species from unaffected areas nearby, epifaunal crawlers or infaunal predators exhibiting the most rapid recovery rates. Conversely, the slow-paced recolonization of completely defaunated areas was due to the modification of sediment properties by drying and to the absence of larvae or juveniles of local species during the experiment.

CARACTERIZAÇÃO DA MACROFAUNA BENTÔNICA EM VIVEIROS DE CULTIVO DO CAMARÃO-BRANCO-DO-PACÍFICO, Litopenaeus vannamei (BOONE, 1931), NO ENTORNO DO ESTUÁRIO DO RIO JAGUARIBE, CEARÁ, BRASIL

“…A predominância de poliquetas capitelídeos em áreas estuarinas é fato comum nos resultados obtidos por trabalhos de caracterização da macrofauna bentônica (Couto et al,, 1995;Mochel, 1999;Franklin-Junior, 2000;Faraco;Lana, 2003;French et al, 2004;Sampaio, 2004;Varadharajan& Soundarapandian, 2013). Segundo Silva (2006), as espécies Laeonereis cf.…”

Variação Em Pequena Escala Da Macrofauna Bentônica Em Uma Planície De Maré Do Estuário Do Rio Pacoti - Ceará, Brasil

“…Em estudos sobre endofauna de planícies lamosas entremarés, Oliveira & Mochel (1999) registraram a mesma taxocenose, porém com valores de dominância de 72% de poliquetas, 15% de crustáceos e 8% moluscos bivalves. A dominância dos poliquetas em áreas estuarinas é fato comum na maior parte dos trabalhos de caracterização de macrofauna bentônica (Couto et al, 1995;Dittman, 2000;Franklin-Junior, 2000;Faraco & Lana, 2003;French et al;2004;Sampaio, 2004). Sampaio (2004) comparou a macrofauna em bosques de mangues do Pará, norte do Brasil, e observou uma dominância dos poliquetas com 72% do total dos invertebrados coletados.…”

Small-scale experimental contamination with diesel oil does not affect the recolonization of Sargassum (Fucales) fronds by vagile macrofauna

“…In contrast, small-scale studies with areas of highly localized defaunation, as simulated in the current experiment where fronds of Sargassum from both treatments (CG and IG) were reintroduced onto intact algal banks, may favor a rapid rate of recolonization and recovery by the original fauna. This was noted by RITCHIE (1995), who examined the effects of crude oil spills, and their derivatives, on different types of shoreline, and FARACO & LANA (2003) who observed the rapid response of polychaetes in peripheral oil spill areas in natural and defaunated subtropical mangrove sediments. In the present study, the similarity in densities of associated fauna, 12 days after treatment, to those in the natural conditions (NC) indicate a rapid rate of recolonization and recovery.…”

“…Some controlled experiments, simulating spillages and their effects compared with areas that have not been affected across many different coastal environments, have been carried out (HYLAND et al 1990, FARACO & LANA 2003. However, no studies have examined the effect of diesel oil on the recolonization process and succession in macrobenthic phytal communities.…”