Temporal and Spatial Distribution of Fish Larval Assemblages of the Tebrau Straits South Western Johore Peninsular MalaysiaBy

A. Arshad, Roushon A., S K Daud & Mazlan A G Department of BiologyFaculty of Science, UPM

Email: azizar@fsas.upm.edu.my

Biological and ecological information on fish larvae is essential for fisheries management.Spawning ground and spawning season could be determined based on the spatio-temporal larval distribution dataTemporal patterns of variation in the composition of assemblages can also be used to determine dynamics of recruitment patterns of fish. Introduction

Objectives of the researchTo establish the list of fish larvae found within the seagrass bed, mangrove, estuarine and open sea of the Tebraus Straits .To determine the composition, abundance and distribution of fish larvae in the study areas.

Materials and MethodsStudy area:The Study were conducted in the Tebrau Straits. Five (5) stations were selected:St.1 (N 010 23.345/; E 1030 36.741/), River Pendas St.2 (N 010 22.790/; E 1030 38.140/), R. Pendas EstuarySt.3 (N 010 21.597/; E 1030 37.491/), Straits/ MangroveSt.4 (N 010 19.414/; E 1030 35.628/), Seagrass bedSt.5 (N 010 18.799/; E 1030 35.246/), Open seasEach sampling station is approximately 1 km apart from each other (Fig.1)

Sampling:Monthly sampling was carried out during full moon/new moon period, at both high and low tides.Samples of fish larvae were collected using Bongo net (Fig.2) through 30 min subsurface net towing.A flowmeter is attached to the net in order to determine the volume of the water filtered.Sampling period: October 2007 to March 2008

Habitat ParametersAt each sampling station, the following environmental parameters are being obtained by YSI multiparameter recorder: Temperature (0C) Dissolved oxygen (mg/L) Salinity (ppt) PH Total dissolved solid (mg/L) & Conductivity (mS/cm)

Sample Processing:After each tow, samples were immediately fixed in 5% formalin and transported to the laboratory for further analysis.Samples were sorted out to family level, taxonomically identified and permanently stored in 75% alcohol.Identification to the family level using the appropriate literatures (Leis and Carson-Ewart, 2000; Kawaguchi, 2002)

Composition & Distribution In the laboratory fish larvae were sorted from the rest of zooplankton. Numerical estimation of larval abundance of different families were counted using a dissecting microscope.

Results

Environmental Parameters: Site AnalysisMean SD of the environmental parameters from the different stations were calculated and from the analysis of variance (ANOVA) stated that there were significant differences (P < 0.05) among the five stations (Table 1)Environmental Parameters: Tidal AnalysisMean SD of the environmental parameters during low tide and high tide were also calculated and showed significant differences (P < 0.05) (Table 2)

Species Composition and AbundanceA total of 34 families were identified. From these, 16 occurred in River, 22 in Estuary, 19 in Strait, 22 in Seagrass bed and 14 in Open sea. Among the 34 families, 13 families are commercially important (Table 3).Overall, 5 families (Clupeidae, Blenniidae, Sparidae, Gobiidae and Sillaginidae) were the most common in term of numbers in the study areas.

Some Photographs of Fish Larvae

Abundance and Spatial DistributionThe highest mean number (240.33 /unit effort) of fish larvae was found in the Merambong seagrass beds.

This was followed by the station 3 located in Tebrau Straits (fringed with mangroves) and lowest in the open sea area (Fig.4)An analysis of variance (ANOVA) stated that there were significant differences between the stations on the basis of abundance of fish larvae (p < 0.05)

Spatio-temporal Distribution

The highest number (1074/unit effort) of fish larvae was found during the month of February in Merambong seagrass bed. (Fig.5)

Lowest number of fish larvae (6/unit effort) was found during the month of October in the upper river station (Fig.5)

Correlation Betn Larval Abundance and Environmental ParametersThere were no significant correlation between abundance of fish larvae and environmental parameters

Parameters X AbundanceCorrelation co-efficient (r)Significance level at 5% levelCommentTemp X abundance-0.073P> 0.05Not significantSal X abundance0.328P> 0.05Not significantDO X abundance0.192P> 0.05Not significantCod. X abundance-0.051P> 0.05Not significantPH X abundance0.212P> 0.05Not significantTDS X abundance0.318P> 0.05Not significant

Lists of Fish larvae known to exist in the coastal waters of Gelang Patah, Johore have been established.A total of 34 different families were identified from the coastal waters of Tebrau Straits, Johore. Summary of results

The average highest number ( 240.33 /unit effort) of fish larvae was found in Merambong seagrass bed and lowest in the open sea.An analysis of variance (ANOVA) stated that there were significant differences between the stations on the basis of abundanceSummary of results

Temporal variations were observed on the abundance of fish larvae, where the highest number (1074/unit effort) of larvae was recorded in the month of February in seagrass bed and the lowest number (6/unit effort) was found in October of River Pendas station.. There were no significant correlation (P > 0.05) between the abundance of fish larvae and environmental parameters.Summary of results

THANK YOU FOR YOUR ATTENTION

Fig.1. Geographical location and three sampling stations

Fig.2. Bongo Net (Mesh size 500 m, mouth diameter 0.3 m and length 1.3 m )

Fig. 4. Photograph of YSI

St-1. River of Pendas

St-2. Estuary

St-3. Straits of Teberau

St-4. Seagrass area

St-5. Open Sea

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