Factors affecting the occurrence of Porphyra vietnamensis Tanaka & Pham-Hoang Ho along the Goa coast

Abstract

Porphyra vietnamensis Tanaka & Pham-Hoang Ho occurs in the intertidal region of the Goa coast, during mon-soon months from June to September. The growth and distribution patterns of P. vietnamensis populations along the Goa coast were studied quantitatively. Data on algal distribution, abundance, biomass and hydro-logical parameters were collected at three sites (Dona Paula, Reis Magos estuarine sites and Vagator open coast), every fortnight for a period of 4 months (June-September 2002). Highest biomass was recorded at Vagator (1.3 kg m sup(-2)) followed by Dona Paula (0.9 kg m sup(-2)) and Reis Magos (0.5 kg m sup(-2)). The study reflected that nutrients (nitrate, nitrite and phosphate) and tem-perature were the factors responsible for the growth of this alga. Among them, phosphate was the main growth-promoting factor at Vagator; this was supported by its positive and significant correlation with the algal biomass. Low temperature was found to be conducive for algal growth, since it exhibited negative and significant correlation with algal biomass. Morphological observation of this alga indicated that thalli growth was relatively larger and well developed at Vagator compared to the other two sites.