Resumen de First record of Trichodesmium Erythraeum Ehrenberg ex Gomont (Cyanobacteria) in the Coastal Waters of Kankesanthurai, Northern Sri Lanka
Sivashanthini Kuganathan, Sivagini Krishnamoorthy, Uventhikka Sivanantham, Nahmagal Krishnapillai, Khalingarajah Harichandra, Sutharshiny Sathyaruban
Trichodesmium erythraeum Ehrenberg ex Gomont 1892 is the most abundant cyanobacterial species in tropical and subtropical waters of the world. The present study reports a dense bloom of the filamentous, colonial cyanobacterium T. erythraeum off Kankesanthurai (KKS) coast, Northern Sri Lanka. A prominent reddish-brown surface water discoloration was observed on a low windy day, 28th March 2021 in the first inter-monsoonal period, during a regular coastal monitoring programme. The bloom persisted only for one day and the physicochemical properties and phytoplankton composition of the coastal waters on the same day were reported. The observed bloom stretched over a length of approximately 6 km along the KKS coastal waters. The main water quality parameters such as surface seawater temperature (30.14–30.69°C), dissolved oxygen (5.91–6.14 mg L− 1), salinity (31.8–33.2 psu), pH (7.57–8.15), nitrate (1.4–2.4 mg L− 1), phosphate (0.18–1.26 mg L− 1) and Chlorophyll-a concentration (4.77–5.97 mg m− 3) were recorded in the area at which the bloom existed. A maximum density of 33750 filaments L− 1 for T. erythraeum was recorded in the bloom site. In addition to T. erythraeum, diatoms and dinoflagellates were also recorded from the water sample. Among the total phytoplankton recorded, T. erythraeum contributed 77%, T. thiebautii contributed only 3% whereas other phytoplankton contributed 20%. The present research paper indicates the first record of T. erythraeum bloom in the KKS coastal waters, Northern Sri Lanka and provides baseline information for future research.
