Hypnea musciformis (Wulfen in Jacqu.) J. V. Lamour. is a native source of kappa-carrageenan, a commercially important galactan, exploited for decades on the northeastern Brazilian coast. Further studies to obtain information about the effects of abiotic factors on the carrageenan yield and quality of specimens from the southeastern Brazilian coast (Rio de Janeiro State) are needed. In this study, the carrageenan yield and quality of H. musciformis was analyzed over a period of 1 year in populations from Rio de Janeiro state. One epiphytic population was collected at a site situated at the entrance of the Sepetiba Bay (Praia Vermelha), another in the middle of the bay (Praia Grande) and a third (Praia Rasa) in a place exposed to the open sea. An epilithic population was also collected at Praia Rasa. In the sampling period, different changes were observed in the carrageenan yield and quality (viscosity and sulphate content) of the H. musciformis (August 1994 to June 1995 at the different sites and habitats (epilithic and epiphytic). Kappa carrageenan was the only one of its type detected. Only one population showed a correlation between viscosity and degree of sulphate content. Our analyses suggest that abiotic factors, such as water movement, desiccation stress, low salinity and extreme temperatures, were the main abiotic factors that influenced the changes in carrageenan of the populations studied. Thus, for a rational use of natural beds of H. musciformis, it is desirable to estimate the changes in carrageenan and algal biomass in the place to be exploited.

RESUMO -(Variação espaço-temporal de populações de Hypnea musciformis (Rhodophyta, Gigartinales) na baía de Sepetiba e Armação dos Búzios, RJ, Brasil). Três populações de Hypnea musciforlllis foram analisadas ao longo do Estado do Rio de Janeiro; duas epifíticas, sublitorãneas, localizadas na baía de Sepetiba (município de Mangaratiba) e uma epilítica, litorânea, localizada em praia exposta a mar aberto (praia Rasa, município de Armação de Búzios). Essas populações foram analisadas quanto à produção de biomassa, flora acompanhante e as possíveis interações com alguns fatores ambientais. As biomassas de H. musciformis variaram nos três locais, não havendo padrão sazonal comum. Observou-se que a movimentação de água, insolação, flora acompanhante e a relação entre a epífita e o hospedeiro, Sargassum spp., causaram efeitos diferenciados sobre a produção das biomassas nas diferentes populações.Palavras chave -Hypnea musciformis, carragenófita, sazonalidade, biomassa ABSTRACT -(Spatial and temporal variation ofpopulations of Hypnea musciformis (Rhodophyta, Gigartinales) in the Sepetiba bay and "Armação dos Búzios", RJ, Brazil). Three populations of H. musciformis were analyzed throughout Rio de Janeiro State; two sublittoral epiphytic populations located in the Sepetiba bay (Mangaratiba municipality), and one intertidal epilithic population on the shore facing the open sea (Rasa beach, Armação dos Búzios municipality). These populations were analyzed for seasonality in biomass production, the accompanying flora species, and the possible interactions with some environmental factors. The biomass production of H. lIluscifonnis was different at each site, water movement, sunlight, accompanying flora, and the relation between the epiphyte and host, Sargassum spp., caused different effecls on biomass production in differenl populations.

The carragenophyte Kappaphycus alvarezii has been introduced into tropical regions, including Brazil, for aquaculture purposes. Our study estimated the biomass loss of farmed cuttings, the establishment of cuttings outside the rafts, the occurrence of spores, and evaluated the invasive potential of K. alvarezii at three sites in Rio de Janeiro state. Temperature, salinity, water transparency, wind velocity and direction (hydrodynamic indicator) and solar radiation (irradiance availability indicator) varied spatially. We found no spores in cultivated cuttings and no verified spore recruitment on artificial substrata. Biomass loss of cuttings varied temporally; however, it was restricted to the cultivation management area of one site and was low compared to native algal biomass. The establishment of cuttings was apparently limited by herbivory at Ilha Grande Bay and controlled by water transparency, hydrodynamics and temperature at Sepetiba Bay. The invasive potential of K. alvarezii was considered remote. However, the use of environmental protocols for cultivation activities is necessary to prevent environmental impacts, mainly in tropical regions.

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