Sains Malaysiana 46(8)(2017): 1191–1200

http://dx.doi.org/10.17576/jsm-2017-4608-04

Factors Influencing the Distribution of Chl-a along Coastal Waters of East Peninsular Malaysia

(Faktor Mempengaruhi Taburan Chl-a di Pesisir Pantai Timur Semenanjung Malaysia)

F. SHAARI & M.A. MUSTAPHA*

School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

Diserahkan: 14 Jun 2016/Diterima: 8 Februari 2017

ABSTRACT

Determination of chlorophyll-a (Chl-a) distribution in the coastal waters is important to understand the coastal environmental conditions. This study was conducted to understand the spatial and temporal distribution of Chl-a along coastal waters of east Peninsular Malaysia and factors influencing its variability using Chl-a data derived from Aqua MODIS satellite (1 km spatial resolution) from January 2006 to December 2012. Chl-a variability was described using empirical orthogonal function (EOF) analysis. In-situ data (temperature, salinity, density and nitrate) and rainfall data from the Department of Meteorology were analyzed using spatial interpolation to determine factors influencing the distribution of Chl-a. The seasonal progressions of Chl-a showed high value during northeast monsoon along the coast. This variability was described by four modes of the EOF analysis. The first mode (72.08% of total variance) indicated seasonal cycle with high variability along the coast. Second mode (17.03% of variance) explained the northeast monsoon with high variability from river mouth to the south. Third mode (2.39% of variance) indicated variability during southwest monsoon along the coast and much higher to the south. Mode 4 (1.93% of variance) explained the inter-monsoon period observed along the northern and southern coastline. Concentration and distribution of Chl-a were related to availability of nutrient influenced by rainfall. The thermohaline front was also observed to play an important role in accumulation of phytoplankton biomass during northeast and southwest monsoon.

Keywords: Chl-a; Coastal waters; empirical orthogonal function (EOF); nitrate

ABSTRAK

Penentuan taburan klorofil-a (Chl-a) di pesisir pantai adalah penting bagi memahami keadaan persekitaran pesisir pantai. Penyelidikan ini telah dijalankan untuk memahami taburan reruang dan masa Chl-a di pesisiran pantai timur Semenanjung Malaysia dan faktor yang mempengaruhi variasi taburan menggunakan data Chl-a daripada satelit Aqua MODIS (1 km resolusi reruang) dari Januari 2006 hingga Disember 2012. Variasi Chl-a diterangkan dengan mengunakan analisis fungsi ortogon empirik (EOF). Data in-situ (suhu, saliniti, ketumpatan dan nitrat) serta data hujan daripada Jabatan Meteorologi dianalisis dengan menggunakan interpolasi reruang bagi menentukan faktor yang mempengaruhi taburan Chl-a. Taburan musiman Chl-a menunjukkan kepekatan tertinggi semasa monsun timur laut dan tersebar di sepanjang pesisir pantai. Variasi ini diterangkan melalui empat mod analisis EOF. Mod pertama (72.08% daripada jumlah varians) menerangkan kitaran bermusim dengan variasi yang tinggi sepanjang pesisir pantai. Mod kedua (17.03% daripada jumlah varians) menerangkan keadaan monsun timur laut dengan variasi yang tinggi di muara sungai ke arah selatan. Mod ketiga (2.39% varians) menunjukkan keadaan monsun barat daya di sepanjang pesisir pantai dan lebih tinggi di bahagian selatan. Mod keempat (1.93% variasi) pula menerangkan keadaan peralihan iaitu di sepanjang bahagian utara dan selatan pesisir pantai. Kepekatan dan taburan klorofil-a di bahagian selatan pesisir pantai didapati berhubungan dengan ketersediaan nutrien yang dipengaruhi oleh curahan hujan. Struktur termohalin didapati memainkan peranan yang penting terhadap pengumpulan biojisim fitoplankton semasa monsun timur laut dan barat daya.

Kata kunci: Chl-a; fungsi ortogon empirik (EOF); nitrat; pesisir pantai

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*Pengarang untuk surat-menyurat; email: muzz@ukm.edu.my