The Monthly Distribution & Abundance of Jellyfish (Medusae) Species in the Coastal Waters of Penang National Park, Penang, Malaysia.

Sim Yee Kwang1 & Khairun Yahya1,2
1Centre For Marine & Coastal Studies (CEMACS), Universiti Sains Malaysia, 11800 USM Penang, Malaysia.
2School of Biological Sciences, Universiti Sains Malaysia, 11800 USM Penang, Malaysia.
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 Summary of Research

A study of monthly abundance and distribution of jellyfish population was conducted for 18-months period around the coastal waters of Penang National Park (PNP), Penang, Malaysia started November 2009 until April 2011. Towing and scooping methods were applied for samples collection using fishing boat cruising at the speed of approximately 2.5 nautical knots during neap tide. The scooping method used visual observation to detect jellyfish from the water surface.  Meanwhile towing method required a custom-made trawl towed behind the boat for submerged jellyfish specimen. A total number of five jellyfish species from five different genera were identified, namely; Phyllorhiza punctata, Chrysaora sp., Rhopilema sp., Chiropsoides buitendijki, and Carybdea morbakka. The dominant Chrysaora sp.contributed up to 96.58% of the total jellyfish catch.  The maximum jellyfish number recorded was 57.07±12.37 individuals/1000m3 in May 2010. No occurrences of significant jellyfish bloom but their presence were observed throughout the whole sampling periods.
 
Physical-chemical parameters recorded were within the normal ranges. pH, temperature, salinity, conductivity, dissolved oxygen, total suspended solid, biological oxygen demand and chlorophyll-a varied between 8.09-8.97, 29.12°C-32.06°C, 28.56ppt-30.30ppt, 47.05µS/cm-53.36µS/cm, 4.26mg/L-6.70mg/L, 36.60mg/L-80.53mg/L, 0.38mg/L-3.19mg/L and 0.33mg/L-2.41mg/L respectively. For nutrient, nitrite, nitrate, ammonia and phosphate varied between 0-0.03mg/L, 0-0.05mg/L, 0-0.02mg/L and 0-0.01mg/L respectively. The concentration of nutrients was positively correlated with the abundance of jellyfish (nitrite, r = 0.414, p<0.01; nitrate, r = 0.521 p<0.01; ammonia, r = 0.294, p<0.01). This implies that sewage discharge, land based pollutants and other human activities result in nutrient loading into coastal waters and causes jellyfish bloom. Thus, the frequency of jellyfish bloom in waters of Penang National Park could act as an indicator for marine environment degradation due to anthropogenic activities.


Key words: Jellyfish (Medusae), Monthly Distribution, Abundance, Water Quality, Coastal Waters, Penang National Park, Malaysia