Mariculture of Perna viridis (green mussel), Perna indica (brown mussel) and Crassostrea
madrasensis (Indian backwater oyster) is getting popular in India but the productivity of this
sector is affected by inadequate supply of spats. The natural spat resources are the only viable
option available to the bivalve farmers to meet the seed requirements. Early detection of the
larvae of the three target species in the plankton samples collected from the coastal waters will be
helpful to predict the time of spat settlement which is crucial for the successful spat collection
using cultch materials. The present work deals with the development of DNA markers in the
form of Species Specific PCR (SSPCR) and Species Specific nested PCR (SSnPCR) for the specific
and sensitive detection of the larvae of three target bivalves from unsorted plankton samples.
Analysis of the experimental plankton samples using SSnPCR proved that the method can detect
even a single veliger larva from a plankton biomass of 40mg. Similarly, SSPCR could be used to
detect a minimum of 20 numbers of veliger larve from a plankton biomass of 40 mg. The SSPCR
could also be used to assess the numerical density of the target bivalve larvae in coastal water
and it was possible to detect approximately 106 larvae in 1000 liters of water. The utility of
SSPCR and SSnPCR was also evaluated in the plankton samples collected from the coastal waters.
The spat collectors placed in the study area were observed to have rich settlement of the target
bivalve larvae showing a positive correlation with the lab results obtained. Screening of the
Plankton samples have proved that these methods can be effectively employed to detect the
presence of the target bivalve larvae in the coastal waters and it can be used as a ‘spat-fall
prediction tool’ to manage the spat collection process more effectively by the bivalve farmers