Quantitative variables applied to phenological studies of Sargassum vulgare C. Agardh (Phaeophyceae - Fucales) from Ilha Grande Bay, State of Rio de Janeiro

Abstract

-(Quantitative variables applied to phenological studies of Sargassum vulgare C. Agardh (PhaeophyceaeFucales) from Ilha Grande Bay, State of Rio de Janeiro). The suitability of quantitative variables for phenological studies was evaluated in a population of the brown seaweed Sargassum vulgare from "Praia das Gordas", Angra dos Reis, Ilha Grande Bay, state of Rio de Janeiro. From June 1998 to May 1999, twenty adult individuals were randomly sampled at bimonthly intervals. Fifteen variables related to the vegetative and reproductive development of perennial and non-perennial parts of the individuals were quantified. Variables related to the non-perennial parts were more useful than those related to the perennial parts, because they showed a clear variation over the year. Vegetative development declined from June to October, and increased from October to February, when maximum median values of thallus height, total dry mass, non-perennial parts dry mass, and degree of branching were reached. This pattern coincided with those described for other species of the genus from warm temperate regions. Thallus height, a usually employed character in other phenological studies of Sargassum, showed lower coefficient of variation (53.2%) than those related to dry mass (72.0% to 182.3%). Peak of reproduction occurred from June to August, according to the following variables: fertile primary lateral branches number and dry mass and receptacles dry mass. Nonperennial parts dry mass and receptacles dry mass are recommended for phenological studies of S. vulgare. This methodological procedure avoids the sampling of the whole individual and warrants its regeneration from the perennial parts.Key words -methodology, reproduction, Sargassum, temporal variation, vegetative development RESUMO -(Variáveis quantitativas aplicadas a estudos fenológicos de Sargassum vulgare C. Agardh (PhaeophyceaeFucales) da Baía da Ilha Grande, Estado do Rio de Janeiro). A população de Sargassum vulgare da Praia das Gordas, Angra dos Reis, Baía da Ilha Grande, Estado do Rio de Janeiro, foi estudada de junho de 1998 a maio de 1999, a fim de avaliar a adequação de variáveis quantitativas para estudos fenológicos desta alga parda. Vinte indivíduos adultos foram coletados aleatoriamente a intervalos de dois meses. Quinze variáveis relacionadas ao desenvolvimento vegetativo e reprodutivo das partes perenes e não perenes dos indivíduos foram quantificadas. As variáveis relacionadas às partes não perenes mostraram claramente variação ao longo do ano, sendo mais úteis do que aquelas relacionadas às partes perenes. O desenvolvimento vegetativo diminuiu na população de junho a outubro e aumentou de outubro a fevereiro, quando valores medianos foram máximos para altura do talo, massa seca total, massa seca das partes não perenes e grau de ramificação. Esse padrão coincidiu com os descritos para outras espécies do gênero em regiões temperadas quentes. A altura do talo, geralmente empregada em outros estudos fenológicos de Sargassum, mostrou menor coeficiente d...

Temporal variation of amphipod assemblages associated with Sargassum filipendula (Phaeophyta) and its epiphytes in a subtropical shore

“…The increase in habitat complexity of sediments and rocky shores provided by macrophytes allows the maintenance of a diverse faunal assemblage, which is an essential component for the energy flow of shallow marine environments (Edgar et al 1994;Nelson and Waaland 1997). However, macrophyte beds present seasonal changes in density, biomass and structural complexity (Leite and Turra 2003;Széchy et al 2006), due to macrophyte phenology and algal community dynamics, including variation from both epilithic and epiphytic species (Borum 1987;Orth and van Montfrans 1984;Széchy and Paula 1997). Thus, the habitat of phytal assemblages is not stable along time, and the assemblages change in response to these biological alterations and to changes in environmental conditions, such as temperature and wave action (Edgar 1983;Johnson and Scheibling 1987;Sánchez-Moyano et al 2001).…”

“…In southeastern Brazil, several species of Sargassum and a great diversity of epiphytes occur mainly in sheltered and semisheltered shores (Széchy and Paula 1997). Within this region, the seasonal fluctuation of host macroalgae and epiphytes can vary among different shores (Széchy et al 2006), possibly resulting in variation of habitat availability for the phytal assemblages (Tanaka and Leite 2003). Amphipod crustaceans and gastropod molluscs dominate these assemblages (Jacobucci and Leite 2002) and commonly respond to variation in epiphyte cover (Leite and Turra 2003), although few studies simultaneously evaluated the relationship among these factors.…”

Distribution of epiphytic macroalgae on the thalli of their hosts in Cuba

“…When the thallus surface has little mucilage, it provides favorable conditions for the establishment of epiphytes (Paula & Oliveira-Filho 1980;Széchy et al 2006).…”

Dimensão fractal e métodos quantitativos aplicados ao estudo de comunidades do macrobentos marinhos

“…As partes que persistem em espécies perenes são o apressório e os ramos principais, que, com o tempo irão aumentar gradativamente de dimensão (PAULA & OLIVEIRA-FILHO, 1980;SZÉCHY et al, 2006).…”

“…Tal como acontece com outros gêneros de Fucales, o crescimento e reprodução do Sargassum é altamente sazonal, tanto em regiões temperadas quanto tropicais e subtropicais (SZÉCHY et al, 2006). A ação de ondas e a interferência do homem no costão rochoso também contribuem para a existência de diferenças significativas na estrutura populacional dessa macroalga (NASSAR et al, 2002;THIBAUT et al, 2005).…”