General Ecology and Habitat Selectivity of Fresh Water Fishes of the Rawan Oya, Kandy, Sri Lanka

Abstract

This study was conducted over a five-month period at Rawan Oya, a 13.5km long left bank tributary of the River Mahaweli. Data on species composition and mircohabitat conditions were collected from 30 random sampling sites, representing 10 pools, 10 riffles and 10 runs. A single observation was made at each site, where a 10m-length of the stream was blocked with drag nets to get the values for abundance. Fishes were captured using the cast nets and scoop nets, identified and released back at the site of capture. The species richness, relative abundance and the microhabitat conditions were recorded for each habitat type. Physico-chemical parameters of water such as the stream velocity, temperature, pH, water depth, conductivity, Hardness, DO and BOD 5 were determined monthly at pre-selected sampling sites. A questionnaire survey was done among people in adjacent villagers, who are selected randomly. A total of 15 fish species belonging to 8 families were recorded of which 2 are endemic and 4 are exotic. The subsequent data analysis revealed that the Shannon Wiener diversity index and the Magalef Index are significantly high in pools. ANOVA test showed significant variation among the 3 habitat types in terms of the microhabitat features measured. Further, the Pearson Correlation test demonstrated that the different fish species have different microhabitat preferences and different habitat associations. Runs seemed to be the most suitable habitats for most of the fish species lotic habitat with the highest species richness compared with the other two habitat types (12 species). Riffles harbored the poorest in species composition (2 species). Pools had an intermediate number of species (9). Puntius bimaculatus, Hypostomus sp and Tor khudree only occurred in pools while Devario malabaricus, Glossogobius giuris, Lepidocephalichthys thermalis, Mystus vittatus, Rasbora daniconius and Xiphophorus maculatus are confined to runs of the stream with no species confined to riffles. Garra ceylonensis and Schistura notostigma occupy all three kinds of habitat types but with higher abundances in riffles. Among the fish found only in pools and runs, Puntius filamentosus were recorded in significantly higher numbers in pools than that in runs in contrast to the alien species such as Poecilia reticulata and Oreochromis mossambicus that showed a higher preference for runs.

Habitat selectivity of fresh water fishes of two second-order tropical streams in Tigray, Northern Ethiopia

“…Consistent sampling design for each site in each sampling period was applied to avoid biased results (Jha et al 2005). Samples in a given stream were taken per the planned time for all the study seasons along an identical trajectory, which included all major river microhabitats (pools, runs, and riffles) (Jones et al 2003;Jayaratne and Surasinghe 2010).…”

“…Monitoring of fish assemblages in wadable streams is principally based on electrofishing methods (Reynolds 1996;Fame Consortium 2005). Before the junction of the two study streams, each stream had 6 sites with 3 habitats each (pools, runs, and riffles) (Jones et al 2003;Newson and Newson 2000;Parasiewicz 2007; Jayaratne and Surasinghe 2010), and each habitat is with two sampling runs (Jayaratne and Surasinghe 2010;Jones et al 2003). Downstream of the confluence point, a site with 3 habitats and 2 runs in each habitat was performed.…”

Fish fauna of Doon Valley, District Dehradun, Uttarakhand, India

“…The overall assessment regarding the family-wise representation all over Doon Valley in general and Eastern and Western drainages in particular, has revealed the domination of the members of family Cyprinidae (Hora and Mukherjii, 1936;Uniyal and Mehta, 2007) as has also been reflected in earlier observations from Himalayas and Doon Valley (Grover et al, 1994;Uniyal, 2002;Johal, 2002;Nautiyal, 2005;Pathani and Upadhyay, 2006;Negi and Negi, 2010b) or other parts of the country (Bhat, 2003(Bhat, , 2004Lakra et al, 2010;Shahnawaz et al, 2010) and abroad (Jayaratne and Surasinghe, 2010;Sumith et al, 2011). This fact lends support to the widely acclaimed fact that Cyprinidae tops the list of 9 largest (most species -rich) families viz., Cyprinidae, Gobiidae, Cichlidae, Characidae, Loricariidae, Balitoridae, Serranidae, Labridae and Scorpianidae (Nelson, 2006).…”

“…The subjects like fish assemblages influenced by environmental factors or fish assemblage variation between geographically defined regions or spatial and temporal characterization of fish assemblages has been an area of interest among Ichthyologists in India (Bhat, 2003(Bhat, , 2004Sreekantha et al, 2007;Lakra et al, 2010;Shahnawaz et al,2010;Vijaylakshmi et al, 2010;Vijaylakshmi and VijayKumar, 2011) and abroad ( Jayaratne andSurasinghe, 2010, Sumith et al, 2011).…”

Diurnal variation in the feeding patterns and food preferences of Dwarf panchax (Aplocheilus parvus)

“…Diverse fish assemblages are distributed in a variety of lentic and lotic freshwater habitats throughout Sri Lanka (Jayaratne and Surasinghe 2010;Goonathilake 2012). Up to now 91 freshwater fish species have been recorded, which consist of 50 endemics and 24 exotics (Goonathilake 2012).…”