Survival in the dark: strategies adopted by Tetraselmis indica (Chlorodendrophyceae, Chlorophyta)

ABSTRACT

The adaptive strategy of Tetraselmis indica to survive darkness was evaluated over a period of 182 days. Resting cells formation and reduction in catabolic activity facilitated dark survival and their rejuvenation. The occurrence of thick-walled cells (type 1) and thin-walled cells with the condensed chloroplast (type 2) in light-dark and dark conditions respectively indicated differential resting cell formation. The dissolved organic carbon remained nearly constant throughout the dark period signifying T. indica did not favour heterotrophy. Upon re-illumination of dark-adapted cells, the lag phase lengthened from 2 to 28 days when darkness period increased from 8 to 182 days, respectively. However, this negative influence on growth was compensated by an increase in growth rate from 0.35 to 0.95 d⁻¹. This resurgence capability of T. indica after six months of dark exposure and distinctive resting cell formation indicate a differential population sustenance mechanism. Further elucidation of dark adaptability and survival strategies in T. indica may have significance in ecological and evolutionary processes.

SUBJECT EDITOR:

• Hongyue Dang

KEYWORDS:

• Tetraselmis indica
• growth
• metabolic activity
• resting cell

Acknowledgements

S.M.N. greatly acknowledges a research fellowship awarded by University Grants Commission, India. S.M.N. is also grateful to Drs V.V.S.S. Sarma, D. Narale, L. Baragi and Mr K. Mapari for their help. This is a CSIR-NIO contribution (6207).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Council of Scientific & Industrial Research (CSIR) funded project Ocean Finder (PSC0105).