Dinoflagellates cyst assemblage concerning trophic index for eutrophication from major ports along the west coast of India

An overview of dinoflagellates cysts assemblage is presented as a trophic index for three monsoon-influenced estuarine and marine ports along the Indian coast. The cyst distribution (including harmful species) showed a trend of highest abundance and species number in highly eutrophicated estuarine (Cochin-south) followed by medium (New-Mangalore-central) and low (Kandla-north) levels of eutrophicated marine ports. The investigation revealed four new species in the region (Bitectatodinium spongium, Gonyaulax elongatum, Brigantedinium sp. and potential harmful species Blixaea quinquecornis-cyst similar to planktonic). Autotrophs dominance in the highly productive Cochin and New-Mangalore ports reveals that, in eutrophic systems, heterotrophs need not always be dominant. The indicator taxa (Polykrikos, Protoperidnium, and Lingulodinium) presence in high density indicated a eutrophic system. This study concludes cyst (species numbers/Fisher-alpha index/indicator species) as potential eutrophication proxies and emphasizes greater harmful-algal-bloom risks in the high trophic-index ports (Cochin and New-Mangalore).

Automated summary

This study presents an overview of dinoflagellates cysts assemblage as a trophic index in three monsoon-influenced estuarine and marine ports along the Indian coast. The investigation reveals the abundance and species number of cysts (including harmful species) are highest in highly eutrophicated estuarine ports, followed by medium and low eutrophicated marine ports. Four new species are found in the region. Autotrophs dominate in highly productive ports, suggesting that heterotrophs are not always dominant in eutrophic systems. The study concludes that cysts can be potential proxies for eutrophication and emphasizes the greater risks of harmful algal blooms in high trophic-index ports.