Author(s): Ratheesh Kumar M, Greeshma VL, Sibin Antony, Vimexen V, Faisal AK, Mohind Mohan, Ajayakumar Varma R, Anoop Krishnan K

Abstract: A temporal, nocturnal sampling along Kavaratti lagoon was conducted in order to find organism(s) exhibiting bioluminescence and factors favoring the proliferation of same. Bioluminescence involves oxidation of luciferin in conjunction with luciferase enzyme. None of the phytoplankton species were found to be bioluminescent. Among the total zooplankton species encountered, only one ostracod crustacean Cypridina hilgendorfii was found to be bioluminescent. Low nutrient values (NO2< 4µmol L-1, NO3< 8.254µmol L-1, NH4 < 0.92 µmol L-1, Inorganic PO4 <0.25 µmol L-1, SiO4< 5.93 µmol L-1) established oligotrophic condition of Kavaratti lagoon. Most of the abiotic parameters have little or no relationship with Cypridina hilgendorfii. However Pearson correlation values showed negative relationship with nitrite (-0.366), ammonia (-0.107) and pH (-0.250). Population of Cypridina hilgendorfii reached its zenith during high tide hours (19840 nos m-3, 17764 nos m-3, 18370 nos m-3). Hierarchical cluster analysis showed a close linkage between Cypridina hilgendorfii and tide. Analysis of variance diagram represented an inverse relationship of Cypridina hilgendorfii with phytoplankton species. This could be explained on the basis of predator prey interaction and active scavenging habit of Cypridina hilgendorfii during night. Bioluminescent glows of Cypridina hilgendorfii serves a variety of functions like illumination, counter illumination, intra specific communication, and defence mechanism from predators. High tide associated with optimum temperature and salinity favoured growth of Cypridina hilgendorfii.

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