Bloom of micro alga Chlorella marina (Butcher) in the Karapad lagoon, Gulf of Mannar, southeast coast of India

Abstract

A study was conducted to find out the possible cause of sudden changes in the colour of the Karapad lagoon water and associated variation in the hydrography. The discolouration of lagoon water was noticed after the excavation work to deepen the lagoon area by the Municipal authorities to enable free boating. Microscopic examination of the lagoon water revealed the blooming of micro alga Chlorella marina. The blooming lasted for a month and has not caused any adverse effect. During the bloom days, the algal cell density attained a peak of 3.1x 105 cells l -1 on 5 th day. Very high chlorophyll concentration was noticed in the lagoon water during the bloom days than the post bloom days. The studies revealed that the nutrient enrichment due to the re-suspension of sediments from the excavation activities might have triggered the algal outburst in the Karapad lagoon. Along with high nutrients, the surface water temperature and salinity might also have supported the algal proliferation.

Hypoxia conditions caused by the Green Noctiluca in the coral reef ecosystem of Tuticorin surface coastal waters along the Gulf of Mannar (Biological Paradise)

“…Furthermore, the surface coastal waters of the Tuticorin coast from Tharuvaikulam Ecopark (west) to Kasuwar Island (east) are a part of marine biological paradise; there have been several actions to put into practice to reduce anthropogenic pressure which affect the paradise. Previous ndings in India on the abrupt arrival of Green Noctiluca on the seawater surface ranged from 1200 Cells/L to 13.5 lakh Cells/L (Gopakumar et al, 2009;Miyaguchi et al, 2006;Gomes et al, 2018;Mishra et al, 2022). However, human activities are not the main cause of blooms; Green Noctiluca species dominated the plankton community during the bloom extent area, with a high concentrated cell density of 5.60 × 10 5 Cells/L in location 5.…”

“…Noctiluca scintillans is a cosmopolitan, heterotrophic dino agellate (Baliarsingh et al, 2016) that is renowned for changing green and red colour water phenomena in the marine waters that produce bioluminescence sporadically (Liu & Hastings, 2007;Gopakumar et al, 2009;Zhang et al, 2017). Noctiluca scintillans is found in two strains: red and green.…”

“…Noctiluca scintillans is found in two strains: red and green. Red strains are fully heterotrophic and develop a slew of carotenoid pigments that provide the distinctive red color whilst, Green strains are symbiotic prasinophytes (green algae) that produce the characteristic green colour (Zhang et al, 2017; Lotliker et al, 2018).The development of green and red colour in waters, creation of bioluminescence, and continued existence in hypoxic and anoxic seas are the ecological characteristics of Noctiluca blooms (Gopakumar et al, 2009;Lotliker et al, 2018). The little oxygen levels induced by the bloom of N. scintillans in uence the coral reef environment and biodiversity (Baliarsingh et al, 2016;Raj et al, 2020).…”

“…Recent outbreaks of Noctiluca scintillans occurrence were reported along east coast (Gopakumar et al, 2009;Misra et al, 2022). Red variants of Noctiluca have been speci ed along the Tamil Nadu coast (Aiyar et al, 1935), the Rushikulya River, and off the coast of south Orissa (Mohanty et al, 2007).…”

“…Red variants of Noctiluca have been speci ed along the Tamil Nadu coast (Aiyar et al, 1935), the Rushikulya River, and off the coast of south Orissa (Mohanty et al, 2007). The Noctiluca scintillans bloom augment saltwater thickness, which requires sh to respire high dissolved oxygen to push saltwater than they obtain from it, resulting in a shortage of dissolved oxygen and hence it leads mortality (Gopakumar et al, 2009). Although much research was put forward to discover the critical cause of the harmful algal bloom (HABs), a conclusion has yet to arrive.…”