Categoria 2: Comunicação de ocorrência de espécies exóticas invasoras
THE FIRST OCCURRENCE OF THE ASIAN CLAM CORBICULA FLUMINAE
(BIVALVIA:CORBICULIDAE) IN PARANOÁ LAKE, BRASÍLIA, BRAZIL
MARTINS-SILVA, M.J.1, PIRES-JUNIOR,O.R.2, RODRIGUES, J.C.A.1, COUTINHO,M.F.2 &
MIRANDA F.R.2
1 – Benthos Laboratory, University of Brasilia. 2 – Toxinology Laboratory, University of
Brasilia.
In a recent past, three species of Asian freshwater bivalves, Corbicula fluminea,
C. largillierti and Limnoperna fortunei, have been introduced into South American
inland waters, since their first report, works of new occurrences in South American
region has been increased (Silva e Souza, 2004).
Corbicula fluminea (Figure 1) was found for the first time in Brazil on 1978 and
was believed to have been introduced to the Guaíba and Jacuí River basins in southern
Brazil (Veitenheimer-Mendes, 1981).
C. fluminea is a freshwater bivalve that lives buried in the sand, this clam can
obstructs pipelines and irrigation canals by achieving population density above 10.000
individuals/m2 (Silva e Souza, 2004).
Paranoá Lake is an artificial reservoir that was constructed in 1959 on purposes
of offering recreation activities and enhancement of the microclimate in Brazil's Federal
Capital, Brasilia. Paranoá Lake has an area of 37,5 Km2, it has four main creeks that
provide water sources: Bananal, Torto, Riacho Fundo and Gama (Figure 2).
Empty shells were discovered casually under Bragetos’ bridge (North Paranoá
Lake) in October 2004 during observations of the Paranoá Lake’s water. In this locality
the empty shells was very abundant (300 individuals /m2), carpeting the lake margins.
Local fishermen reported that these mollusks appeared around 4-5 years ago.
Shells were manually collected inside of 1 m2 area and the alive shells were
captured by a D Net in February/2005. The sampled bivalves were counted and
measured with an electronic digital calipter. The approximate age of C. fluminea found
was calculated (Cataldo and Boltovskoy, 1998). To observe the occupation of C.
fluminae the lake was traveled all over its extension (Figure 2)
Suggesting that the biggest shell may belongs to the first generation, based on
length we predict that the biggest shell found (39.63 mm) had about 4-5 years,
supporting fishermen observations. Almost all collected shells belong to the class
length (20.0-25.0 cm)
The early sexual maturity, high reproductive potential and a remarkable ability
to occupy different environments makes this species an aggressive invasor. These
characteristics can provoke a drastic decline of native’s bivalves populations. In Paraná
and Paranapanema River, Takeda et al (2000) predicted that some native molusks
populations were decreasing in consequence of the presence of this asian clam. The
Paranoa Lake malacofauna is poorly known, up to now only two native bivalves were
found in Paranoá Lake Psidium sp and Diplodon sp. and one invasive gastropod
Melanoides tuberculatus. Although we do not known if this species are overlaping
theirs niches causing competition. Some studies show that this clam accumulates toxic
substances in its tissues, therefore may prove a threat to human health because they
are a food resource for the fish that humans eat.
Silva, J.S.V and Souza, R.C.C.L (2004) Água de lastro e bioinvasão – Rio de Janeiro:
Interciência 224p.
Takeda, A. M.; Higuti, J.;Fujita, D. S., & Bubena, M. R., (2000) Proliferação de uma
espécie de bivalve invasora, Corbicula fluminae, na área alagável do Alto Paraná
(Brasil). In: Seminário Brasileiro sobre água de lastro, 1, Arrail do Cabo, p.11.m
Figure 1. Corbicula fluminea collected under Brageto’s bridge of Paranoá Lake, BrasíliaDF
Figure 1. Paronoá Lake localization in Brazil. Assigned area means the local of
Corbicula fluminea first observation.