Impacts of disturbance on fish communities in Sungai Pur, Terengganu

Abstract

There are a few experimental studies regarding the response of stream fish towards human-induced di sturbance conducted in the past; with studies often addressed the effects of disturbance and fish assemblages resiliency over long time interval. This study aim to investigate the effects of human-induced disturbance by electrofishing towards the abundance of fish species and the ability of the fish assemblages to bounce back to its original pre-disturbance species composition. Study was conducted at Sg. Pur, Kuala Berang in Hulu Terengganu District, Terengganu. Four stations, Station A, Station B, Station C and Station D was set up at the area. Each station then divided into two substation, 1 and 2. The first sampling was considered as the pre-disturbance model and sampling was performed in all the substations. The second sampling was considered as two months post di sturbance period with sampling only carried out in substation A2, B2, C2 and 02. The last sampling was the four months post disturbance period and sampling was performed in substations A 1, B 1, C 1 and D 1. The result demonstrated that the first sampling was the sampling occasions with the most number of fish and their species captured while the second sampling vice versa. The five most abundant species were Rasbora sp., Rasbora natura, Nemacheilus selangoricus, Systomus banksi and Osteochilus waandersii. The abundance of fish assemblages was greatly reduced after the disturbance as demonstrated by the number of fish captured during two months post disturbance period. However, after four months, the abundance of fish assemblages and the amount of species present at the substations were increased. Similarity Index indicated similarity between first sampling and second sampling, first sampling and third sampling and hi gh similarity between second sampling and third sampling. It was discovered that all five of the most abundant species came from the same family, Cyprinidae. The major characteristic of this family is it is highly mobile, thus facilitate recolonization. The seasonal variation during sampling occasions also proved to influence the number of fi sh captured. High similarity between sampling occasions show that recovery of species composition occurred within a short time which was less than two months. It is hope that this study facilitates other researchers to predict the effects of human-induced di sturbance towards species abundance and the fish assemblages' recovery in short term accurately, thus, assists in the conservation efforts not only for fish assemblages but also stream itself as a whole.