Research communica ons - NF-POGO alumni Nashad Musaliyarakam Nansen Environmental Research Centre and Department of Marine Biology, Microbiology & Biochemistry, University of Science and Technology, India. Wikipage: h p://www.nf-pogo-alumni.org/~Nashad+Musaliyarakam
On the Occurrence of Trichodesmium erythraeum (Ehrenberg) bloom along the southwest coast of India (Arabian Sea) uring the last several decades, harmful algal bloom (HAB) events have been observed in more loca ons than ever before, throughout the coast of India. There have been 39 causa ve species responsible for blooms of which NocƟluca scinƟllans and Trichodesmium erythraeum are the most common. Repor ng of massive fish mortality in Indian waters has been associated with the blooming of Cochlodinium polykricoides, Karenia mikimotoi, K. brevis, Trichodesmium erythraeum, T. thiebauƟi and ChaƩonella marina. Occurrences of these blooms are coincided with South west monsoon and North east monsoon. Around eighty blooms were recorded during the period 1998-2012. Poten ally toxic microalgae recorded from the Indian waters were Alexandrium spp., Gymnodinium spp., Coolia monoƟs, Prorocentrum lima, Dinophysis spp., and Pseudo-nitzchia spp. (Padmakumar et al., 2012). The incidence of a large scale Trichodesmium erythraeum bloom along the southwest coast of India observed on 30th April 2014 is accounted. It is a marine cyanobacterium, an important nitrogen fixer in the sea. It is one of the common bloom forming species found in the tropical and sub-tropical waters, par cularly in the eastern tropical Pacific and Arabian sea (Westberry et al., 2006). Trichodesmium normally occurs in macroscopic bundles or trichomes and blooms formed by it are o en extremely patchy with yellowish brown color. The blooms appeared during rela vely high temperature condi ons (30.5 - 31.8 °C) when coastal water salinity was greater than 31 psu (31.47 - 33.82). A significant reduc on in nitrate concentra on was no ced during the bloom period, whereas rela vely high concentra ons of phosphate were observed. DO concentra on ranged from 6.4 - 8.0 mg L-1. These condions favor abrupt increases in Trichodesmium density (2.16 - 2.32 106 filaments L-1), contribu ng 99.58% to total plankton community. Blooms cons tuted both individual trichomes and colonial forms although later dominated up to 95%. Low zooplankton biomass was found in bloom area with respect to non blooming regions. Harpac coid copepods were dominated followed by Chaetognatha. Trichodesmium is not a food source for most of the zooplankton and this may have been the reason for the low mesozooplankton biomass in the mixed layer.
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References Padmakumar, K.B.; Menon, N.R.; Sanjeevan, V.N., 2012. Is occurrence of Harmful Algal Blooms in the Exclusive Economic Zone of India on the rise? Interna onal journal of oceanography. Vol. 2012, Ar cle ID 263946, 7 pp. Westberry, T.K.; Siegel, D.A., 2006. Spa al and temporal distribu on of Trichodesmium blooms in the world’s oceans. Global Biogeochem Cycles 20:GB4016. Trichodesmium bloom - off Calicut, Kerala, India and at 10X magnifica on (Trichodesmium erytraeum)
Details of the loca on and nutrients of the bloom site
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