Turbelários límnicos (Platyhelminthes) em ecossistemas de arroz irrigado da Planície Costeira do sul do Brasil

Abstract

Turbellarians occur in a variety of wetlands, being also abundant in temporary water bodies. Several turbellarians are top predators in their microhabitats, many of them feeding on zooplankton. However, they are seldom taken into account in biodiversity studies. Information on turbellarian diversity in Brazilian freshwater ecosystems mainly came from taxonomical studies. In southern Brazil, there are a high number of wetlands, most of them represented by rice fields. Despite their impact on natural areas, these managed ecosystems can play an important role in freshwater biodiversity conservation. The aim of the present work was to report on an inventory done in irrigated rice fields of three areas of the Coastal Plain of southern Brazil, viz. Cachoeirinha, Santo Antônio da Patrulha e Camaquã. We found 144 species of freshwater turbellarians, distributed in six taxonomic groups (Catenulida, Macrostomida, Lecithoepitheliata, Proseriata, Rhabdocoela, and Tricladida). Twenty-three species are recorded for the first time for Brazil. Catenulida showed the highest relative abundance in Cachoeirinha, followed by Rhabdocoela. In Santo Antônio and Camaquã, Tricladida had the highest relative abundance, followed by Catenulida. Results suggest that some turbellarian species show a high level of habitat specificity with only 38% of the registered turbellarians occurring in a single study area. Although there is a paucity of turbellarian inventories in Brazilian natural wetlands, hampering a comparison between natural and managed wetlands, results indicate high species richness in the areas studied. Resumo: Os turbelários são encontrados em uma grande variedade de hábitats aquáticos, sendo abundantes inclusive em áreas úmidas temporárias. Diversos turbelários são predadores de topo nos seus microhabitats, muitos deles alimentando-se de zooplâncton. No entanto, raramente os turbelários são considerados em inventários de diversidade. Informações sobre sua diversidade nos ecossistemas límnicos brasileiros provêm principalmente de estudos taxonômicos. No Rio Grande do Sul, há um grande número de áreas úmidas, sendo a maioria delas representadas por lavouras de arroz. Esses ecossistemas manejados, embora tenham alto impacto sobre áreas naturais, podem exercer um importante papel na conservação da biodiversidade aquática. Este estudo teve por objetivo inventariar os turbelários ocorrentes em áreas de cultivo de arroz irrigado de três localidades da Planície Costeira do sul do Brasil (Cachoeirinha, Santo Antônio da Patrulha e Camaquã). Foram registradas 144 espécies de turbelários, distribuídas em seis grupos taxonômicos (Catenulida, Macrostomida, Lecithoepitheliata, Proseriata, Rhabdocoela e Tricladida). Vinte e três espécies são registradas pela primeira vez para o Rio Grande do Sul. Catenulida apresentou a maior abundância relativa em Cachoeirinha, seguida por Rhabdocoela, enquanto nas outras duas localidades, a maior abundância relativa foi de Tricladida, seguida por Catenulida. Os resultados sugerem que algumas espéci...

Microturbellarians (Platyhelminthes and Acoelomorpha) in Brazil: invisible organisms?

“…Such records were mainly distributed among São Paulo, Rio Grande do Sul and Paraná (Marcus, 1943(Marcus, , 1944(Marcus, , 1945a(Marcus, , 1951(Marcus, , 1954Gamo and Leal-Zanchet, 2004;Vara and Leal-Zanchet, 2013;Braccini and Leal-Zanchet, 2013). Considering the freshwater groups, the temnocephalids certainly constitute an exception, with species recorded for various regions in Brazil (Monticelli, 1899;Cuocolo, 1940, 1941;Ferreira Yuki et al, 1993;Damborenea, 1994;Ernst and Lovich, 1996;Vianna and Melo, 2002;Amato et al, 2003, , 2006Seixas et al, 2010aSeixas et al, , b, c, 2011Seixas et al, , 2014.…”

“…Prolecithophorans inhabit freshwater and marine environments, but they have no records in Brazilian freshwater ecosystems (Vara and Leal-Zanchet, 2013;Braccini and Leal-Zanchet, 2013). The members of this taxon were sampled in marine environments on coastal areas of the state of São Paulo (Table 1).…”

“…Most marine turbellarians are limited to the littoral zone of the ocean (Hyman, 1951). Freshwater forms may occur in temporary or permanent wetlands, such as lakes, natural or artificial ponds, pools, ditches, streams and rivers (Kolasa, 1991;Noreña-Janssen, 1995;Young, 2001), as well as in agroecosystems (Bambaradeniya et al, 2004;Vara and Leal-Zanchet, 2013). Some marine flatworms, such as acoels and polyclads, and freshwater rhabdocoels are planctonic (Hyman, 1951;Rocha et al, 1990;Dumont et al, 2014).…”

“…In addition, a new species of marine rhabocoel was recently described (Reygel et al, 2014). Freshwater turbellarians from southern Brazil were investigated by Gamo and Leal-Zanchet (2004), Vara and Leal-Zanchet (2013) and Braccini and Leal-Zanchet (2013) in natural wetlands and agroecosystems. Temnocephalids from various Brazilian regions were studied by Monticelli (1899), Cuocolo (1940, 1941), Amato et al (2003Amato et al ( , 2006Amato et al ( , 2007Amato et al ( , 2010Amato et al ( , 2011, and Seixas et al (2010aSeixas et al ( , b, c, 2011Seixas et al ( , 2014.…”

“…Material collected by the net should be transferred to plastic vials containing water from the sampling site. The vials should be transported to the laboratory and carefully examined under a stereomicroscope (Braccini and Leal-Zanchet, 2013;Vara and Leal-Zanchet, 2013). For sorting, samples may be treated by the method of reduction of oxygen (Schockaert, 1996) or by examining all sampling water under the stereomicroscope (Brusa et al, 2003).…”