Abundância relativa e distribuição de Loricariichthys spixii (Steindachner) (Siluriformes, Loricariidae) no reservatório de Lajes, Estado do Rio de Janeiro, Brasil

Abstract

ABSTRACT. Relative abundance and distrib ution of Loricariic ht hys SplXII (Steindachner) (Siluriformes, Loricariidae) in the Lajes reservoir, Rio de Janeiro State, Brazil The armored calfish Loricoriichthys ~pixii (Sleindachner, 1882) is lhe mOSI abundanl member of lhe Loricariidae family in the Lajes reservoir (22°42'-22°50'S 43°53'-44°05'W), the largest dam in the State ofRio de Janeiro State, bullittle is known about its biology and life cyc\e. A standardized fish sampling program in tlu'ee zones of the reservo ir (Iower, middle and upper reaches), during three annual cyc\es: monthly in 1994/ 1996 and bi -monlhly in 1997 was conducted out aiming to assess and add knowledge of the population structure of this species. Fishes were caught using gill nels (50 m long, 3 m deplh and 25 to 45 mm meshes), amounting 160 samples. Water temperature, pH and transparency were registered at each sample to correlate with fish abundance. Loricariichthys ~pixii (Steindachner, 1882) was the most abundant fish species in the reselvoir, contributing about on third of the total nllmber and half ofthe tota l weight ofthe catches, but a decreasing trend was observed over the three year 01' the study, with num bel' and biomass being significantly more abundant in 1994, followed by 1996 and 1997. There is no clear dependence between environmental parameters and fish occurrence, excepl for the coincidence of decreasi ng tish abundance and decrcasing leveIs ofwater ofthe reservoir over the three year. Fishes were more abundant in lhe high and intell11ediate reaches ofthe reservoir, near to mOllth ofthe tributaries. Seasonally, there is no clear variation in relative abundance. The success of use of lhe reservoir by L. ~pixii could be atlributed to availability of l11uddy and sandy subslrate associated with its k-strategy by carrying eggs, which could allow this species fàces the environmenlal changes of the reservoir, mainly the variations in leveI of water, by hydroelectric power demand o KEY WORDS. Lajes, reservoir, Loricariidae, di stribution, environmental parameters.A famí lia Loricariidae reúne espécies vulgarmente conhecidas como cascudos e cascudos-vio la, sendo caracterizadas por apresentar o corpo revestido por p lacas ósseas, boca inferior e lábios desenvolvidos em forma de ventosa (NELSON 1994). Constituem um dos grupos mais numerosos de peixes Siluriformes neotropicais, compreendendo aproximadamente 600 espécies reconhecidas. Têm sua distribuição limitada à América do Sul e Centra1 -Panamá e Costa Rica (FOWLER 1954;NELSON 1994). REGAN (1904)

Morphology of gonads, maturity and spawning season of Loricariichthys spixii (Siluriformes, Loricariidae) in a Subtropical Reservoir

“…This disturbance could contribute to the wide reproductive period, a mechanism to increase eggs and juvenile survival by the species. Duarte and Araújo (2001) found a close relationship between the water level and L. spixii abundance and attributed this pattern to the increased feeding resources availability and shelter during the high water level season. Overall L. spixii probably found in Lajes reservoir favorable environmental conditions to its development, as indicated by its remarkable high abundance in this relatively closed environment.…”

“…It has successfully adapted to manmade lakes formed from impounded rivers, where fish composition has shift in response to changes in hydrological system (Duarte and Araújo, 2001). Few studies on its reproduction at Lajes reservoir, the largest man-made lake in Rio de Janeiro State, are available.…”

Population structure and reproductive biology of Loricariichthys melanocheilus Reis & Pereira, 2000 (Siluriformes: Loricariidae) in the rio Ibicuí, Brazil

“…Tos et al (1997) and Duarte & Araújo (2001) also observed preference for lentic environments by Loricariichthys platymetopon and L. spixii in the rio Paraná and in the Lajes reservoir (State of Rio de Janeiro), respectively. Lowe McConnell (1999) states that a higher concentration of fish is expected in lakes during the dry season because of water retraction in wetlands.…”

“…Studies conducted on the genus Loricariichthys have focused primarily on L. anus (Valenciennes, 1835), L. platymetopon Isbrücker & Nijssen, 1979(Tos et al, 1997Querol et al, 2002;Marcucci et al, 2005;Bailly et al, 2011) and L. spixii (Steindachner 1881) (Duarte & Araújo, 2001). So far, there is no record in the literature of studies addressing aspects of the biology of Loricariichthys melanocheilus, probably because it is a recently described species and is not widely distributed along several Brazilian basins, but rather, restricted only to the southern region of Brazil.…”

Habitat preferences of common native fishes in a tropical river in Southeastern Brazil

“…Similarly to T. striatulus and H. littorale, L. castaneus preferred slowly flowing waters in areas with sandy and gravel substrates, although the latter two species occurred primarily in shallow water (depth < 4 m). These three Siluriformes are typical fishes of lentic or slow-moving systems (Suzuki et al, 2000;Duarte & Araújo 2001;Santos et al, 2010) and were found in a wide range of microhabitats and aquatic systems, including reservoirs (Araújo & Santos, 2001), shallow riverine zones Terra et al, 2010), and floodplains (Hostache & Mol, 1998). Fig.…”