Discovery of the Critically
Endangered annual killifish Austrolebias wolterstorffi (Ahl, 1924)
(Cyprinodontiformes: Rivulidae) in Lagoa do Peixe National Park, Rio Grande do
Sul, southern Brazil
L.E.K. Lanés 1& L. Maltchik 2
1,2 Laboratory of Ecology and
Conservation of Aquatic Ecosystems, University of Vale do Rio dos Sinos
(UNISINOS). Av. Unisinos 950, Bairro Cristo Rei, CEP 93022-000, São Leopoldo,
Rio Grande do Sul, Brazil.
Email: 1 lelanes@gmail.com, 2 maltchik@unisinos.br
Date of
publication (online): 26 October 2010
Date of
publication (print): 26 October 2010
ISSN
0974-7907 (online) | 0974-7893 (print)
Editor: Carlos Alberto S de Lucena
Manuscript details:
Ms # o2499
Received 02 June 2010
Final revised received 17
August 2010
Finally accepted 02 September
2010
Citation: Lanés, L.E.K. & L. Maltchik (2010). Discovery of the critically
endangered annual killifish, Austrolebias wolterstorffi (Ahl, 1924) (Rivulidae: Cyprinodontiformes) in Lagoa do Peixe National
Park, Rio Grande do Sul, southern Brazil. Journal of Threatened Taxa 2(11):
1282-1285.
Copyright: © L.E.K. Lanés & L. Maltchik2010. Creative
Commons Attribution 3.0 Unported License. JoTT allows unrestricted use
of this article in any medium for non-profit purposes, reproduction and
distribution by providing adequate credit to the authors and the source of
publication.
Acknowledgements:This research was supported by funds from UNISINOS
(02.00.023/00-0) and CNPq (52370695.2). Luis Esteban Krause Lanés has scholarship
masters of the CNPq and Leonardo Maltchik
holds a Brazilian Research Council - CNPq Research
Productivity grant. The material was obtained under MMA/IBAMA/ICMBio
permits (18576-1). This manuscript was improved by the comments of two
anonymous reviewers.
Abstract: This
paper documents the discovery of the rare and Critically Endangered annual
killifish Austrolebias
wolterstorffi in temporary
wetland of Lagoa do Peixe National Park, an important conservation unit of
southern Brazil protected under the Ramsar Convention and recognized Biosphere
Reserve.
Keywords:Annual fish, Cynolebiasinae, endemic,
freshwater, Neotropics, protected areas, Ramsar sites, restricted-range fishes,
threatened species, wetlands.
For figure &
images -- click here
The neotropicalaplocheiloid genus Austrolebias Costa comprises 40 small annual killifishes
endemic to South America, distributed in southern Brazil, southern Bolivia,
Paraguay, Uruguay and northeastern Argentina (Costa 2010). Their highest diversity occurs in
Uruguay and southern Brazil, where several distinct species may be found
sympatric or syntopic. Austrolebias populations live in shallow temporary wetlands
formed close to rivers, streams and lagoons during the rainy season, and die
off when the pools dry (Costa 2003, 2006). Their eggs survive the dry season and hatch after the next
rainy season begins.
The genus Austrolebias has recently been redefined phylogenetically
by Costa (2006), including the species previously referred to the genus Megalebias Costa. Subsequently the genus Austrolebias was divided into subgenera (Costa 2008),
according to clades defined in Costa (2006). Accordingly the subgenus Megalebias which has
the same general geographic range as Austrolebias, comprises five valid species: Austrolebias cheradophilus (Vaz-Ferreira, Sierra de Soriano &
Scaglia-de-Paulete, 1964), Austrolebias
elongatus (Steindachner,
1881), Austrolebias
monstrosus (Huber, 1995), Austrolebias prognathus (Amato, 1986), and Austrolebias wolterstorffi (Ahl, 1922). They can reach a large size (about 70-120 mm SL), making
some the largest among the family Rivulidae (Costa 1998, 2001). These large species are generally rarer than
smaller species that are often abundant in their habitats (Costa 2009), probably
due to increased energy demand as a function of larger body size (Laufer et al.
2009; Arim et al. 2010).
Austrolebias wolterstorffi (Image 1) the type-species of the Megalebias subgenus is a medium size species (compared
with other species of rivulid fishes) reaching about 78mm, endemic to the
Laguna dos Patos hydrographic system and adjacent coastal drainages in southern
Brazil and eastern Uruguay. The
species feeds mainly on mollusks and is the most specialized of the
moluscivorous Austrolebias (Costa 2009). Austrolebias
wolterstorffi is considered
Critically Endangered by the red books of threatened fauna of Rio Grande do Sul
State (Reis et al. 2003) and Brazil (Rosa & Lima 2008), due to the
extensive alteration and loss of wetlands in that region, through anthropogenic
activities, especially agriculture. The species is considered vulnerable to developments of forestation
with exotic species (e.g. Eucalyptus, Acacia and Pinus) (ZAS
2007).
According to previous studies the record of A. wolterstorffi closest to the Lagoa do Peixe National Park
was for the São Caetano locality, more than 100km of protected area (see the
map in Costa 2006). This paper
documents the discovery of the species in Lagoa do Peixe National Park and
presents recommendations for its conservation in southern Brazil.
Material examined: A female (46.35 SL) was captured on 28 June
2008 in shallow (33.17 ± 5.16 cm depth) palustrine temporary wetland, 31006’55”S
& 50050’57”W (Image 2), during a field trip of a research project
conducted by the Laboratory of
Ecology and Conservation of Aquatic Ecosystems, University of Vale do Rio dos
Sinos (UNISINOS). The purpose of
the project was to establish the diversity and distribution of annual
fishes in Lagoa do Peixe National Park (Fig.
1). Water samples revealed the
following parameters: pH: 6.52 ± 0.1; dissolved oxygen: 9.36 ± 0.91 mg/l;
conductivity: 41.17 ± 10.83 mS; and water temperature: 15.69 ± 0.38 0C. The specimen collected by hand net
(D-shaped, 30cm width) was
euthanized with a lethal dose of phenoxyethanol, fixed in situ with 10% formalin
and later transferred to 70% ethanol. Measurements were made with an electronic digital caliper reading to the
nearest 0.01mm, and material was vouchered in collections of fishes of Museu de
Ciências e Tecnologia da Pontifícia Universidade Católica do Rio Grande do Sul
(MCP 44520). The material was
identified based on Costa (2006).
Diagnosis: According to Costa (2006), A. wolterstorffi is distinguished from the remaining species of
the Megalebias subgenus by having fewer scales in longitudinal (31-35 vs. 50-75), minute contact organs on uppermost
pectoral-fin ray in males (prominent contact organs on most pectoral-fin rays),and
a greater number of branchiostegal rays(7 vs. 6).
Austrolebias
wolterstorffi is considered a restricted-range fish (Nogueira et al. 2010), and there
are only two previous records of the occurrence of the species in
protected areas of Brazil, both in Rio Grande do Sul state: Delta do Jacuí
State Park (Reis et al. 2003) and Private
Natural Heritage Reserve of Pontal da Barra (Volcan et al. 2009). Although these populations are
theoretically protected, these areas have many conflicts of land use, and
growing urbanization threatens the habitats of vulnerable species. Despite presenting a relatively wide
area of distribution along the Coastal Plain of Laguna dos Patos hydrographic
system (Costa 2006), records of A. wolterstorffi in the
northern portion of the system, where the species has more representation in
ichthyological collections are increasingly rare (Reis et al. 2003). In the south of the Laguna dos Patos,
Lanés et al. (2005) documented the occurrence of A.
wolterstorffi in a private area of municipality of Pelotas, near to Pontal da
Barra swamp, and Porciúncula et al. (2006) and Quintela et al. (2007) recorded
the species in coastal adjacent drainage to this hydrographic system in Rio
Grande municipality, an important wetland located in the industrial district of
this city.
The Lagoa do Peixe National Park (LPNP) is the
only conservation unit in southern Brazil protected under the Ramsar
Convention. The LPNP presents a
variety of continental, estuarine and marine wetlands, ensuring the survival of
a wide variety of species of several groups of organisms. Is recognized Biosphere Reserve and
integrates various networks for the protection of waterfowl in the world, such
as the Western Hemisphere Shorebird Network. Although several surveys of fish fauna in the
area of the park have been made, only recently has killifish diversity has been
revealed. Costa & Lanés (2009) describe Rivulus riograndensis a freshwater non-annual killifish whose
type-locality is Pai João swamp in Lagoa do Peixe National Park, and Correa et
al. (2009) documented the occurrence of Austrolebias minuano Costa
& Cheffe, 2001 in park area, a species endemic to southern Brazil and
threatened in the category “endangered” (Reis et al. 2003; Rosa & Lima
2008).
Based on the recent records of endangered
killifishes, Lagoa do Peixe National Park, traditionally recognized for its
biodiversity related to marine and estuarine ecosystems, is recognized now for
its importance in the conservation of these endangered species that present
restricted distribution and are exclusive of continental wetlands. These are the most threatened ecosystems in
southern Brazil, and studies suggest that over 90% of natural wetlands have been
lost (Rolon et al. 2008; Maltchik 2010), especially due to drainage for
irrigated rice production (Fontana el al. 2003).
Although the record of A. wolterstorffi for LPNP is important, it is required for
their conservation and that wetlands of southern Brazil be preserved from
agriculture and exotic forestry expansion, since these are the most threatened
ecosystems in this region and are habitat to several endemic and endangered
species. In addition, studies are
needed to assess the population status ofA. wolterstorffi in protected
areas, establish priority areas for conservation, perform bio-ecological
research and establish the inclusion of species in the IUCN Red List of
Threatened Species. These
recommendations apply also for other Austrolebias species
endangered and endemic to southern Brazil.
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