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Temporal and Spatial Distribution of Fish Larval Assemblages of the Tebrau Straits South Western Johore Peninsular Malaysia. By A. Arshad, Roushon A., S K Daud & Mazlan A G Department of Biology Faculty of Science, UPM Email: [email protected]. Introduction. - PowerPoint PPT Presentation
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Temporal and Spatial Distribution of Fish Larval Assemblages of the Tebrau Straits
South Western Johore Peninsular Malaysia
By
A. Arshad, Roushon A., S K Daud & Mazlan A G Department of Biology
Faculty of Science, UPM
Email: [email protected]
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 data
Temporal patterns of variation in the composition of assemblages can also be used to determine dynamics of recruitment patterns of fish.
Introduction
Objectives of the research
1. To establish the list of fish larvae found within the seagrass bed, mangrove, estuarine and open sea of the Tebrau’s Straits .
2. To determine the composition, abundance and distribution of fish larvae in the study areas.
Materials and Methods
Study 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 Estuary
St.3 (N 010 21.597/; E 1030 37.491/), Straits/ Mangrove
St.4 (N 010 19.414/; E 1030 35.628/), Seagrass bed
St.5 (N 010 18.799/; E 1030 35.246/), Open seas
Each 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 Parameters
At 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 Analysis
Mean ± 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 Analysis
Mean ± 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 Abundance
A 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
Cynoglossidae, 50x Clupeidae. 40x Tetraodontidae, 50x
Triacanthidae, 40x Monacanthidae, 50xLeiognathidae, 100x
Blenniidae, 50x Cynoglossidae, 45x
Belonidae, 50x
Syngnathidae, 25x
Gobiidae, 50x
Samaridae, 50x
Unidentified, 100x
Sillaginidae, 50x
Unidentified, 50x
Abundance and Spatial Distribution
The 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)
50.17
103.67
26.67
240.33
160
0
50
100
150
200
250
300
River Estuary Strait Seagrass Off shore
Study sites
Mea
n fis
h la
rvae
(nos
/uni
t eff
ort)
Fig.4. Spatial distn of fish larvae
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)
MONTH
Mar 08Feb 08Jan 08Dec 07Nov 07Oct 07
Ab
un
da
nce
(n
os.
/ un
it e
ffort
)1200
1000
800
600
400
200
0
Station
River
Estuary
Strait
Seagrass
Off shore
Fig.5. Temporal and spatial distribution of fish larvae
Correlation Betn Larval Abundance and Environmental Parameters
Parameters X Abundance
Correlation co-efficient (r)
Significance level at 5% level
Comment
Temp X abundance
-0.073 P> 0.05 Not significant
Sal X abundance 0.328 P> 0.05 Not significant
DO X abundance 0.192 P> 0.05 Not significant
Cod. X abundance -0.051 P> 0.05 Not significant
PH X abundance 0.212 P> 0.05 Not significant
TDS X abundance 0.318 P> 0.05 Not significant
There were no significant correlation between abundance of fish larvae and environmental parameters
• 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 abundance
Summary 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 µm, 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