Abstract
Two sites, in which Rhodophyta and Chlorophyta were the dominant algae, were selected in the intertidal zone of a sandstone reef at Piedade Beach to evaluate macroalgal recruitment and succession from March 2007 through January 2008. At each site, 2 meter transects were sampled using 20 x 20 cm quadrats in the midlittoral zone of the reefflat. The initial position of the quadrats was randomly chosen. Green algae (filamentousand foliose) showed a bloom at the end of the rainy season (approximately 250 grams of dry weight/m2 on October 2007), as indicated by the differences between the monthly average biomass values observed in the recruitment plots. The biomass measurements of control quadrats and in the succession treatments did not differ statistically during the rainy season for either Chlorophyta or Rhodophyta at Site 1 or during the dry season at Site 2. Green and red algae (filamentous and corticated) exhibited a pattern of alternating oscillations, as shown by the principal component analysis of recruitment, rainfall and air temperature. These results suggested a negative relationship between temperature and the recruitment of red algal biomass. Key words: Macroalgal Biomass, Benthic Ecology, Sandstone Reefs, Ecological Succession, Algal Recruitment.
Highlights
The sandstone reefs located in the southern littoral area of Pernambuco State are generally parallel to the coast and are not always exposed at low tide
The green algal biomass in the control plots was statistically different in August 2007 at Site 2 from the biomass sampled from these non -manipulated plots in March 2007 and January 2008 (Figure 1), whereas no such statistical differences were found for the biomass of the red algae collected from the control plots at Site 1
No statistical differences between the biomass on the succession and the control quadrats were found for the red algae (U=2, Z=1.091, p>0.05) or for the green algae
Summary
The sandstone reefs located in the southern littoral area of Pernambuco State are generally parallel to the coast and are not always exposed at low tide They furnish the main hard substrate for the attachment of benthic algae in the region (Sousa and Cocentino, 2004). Mansilla and Pereira (2001) have observed reduced Rhodophyta biomass and algal diversity on a reef further south in Pernambuco’s littoral during the rainy season, compared with samples collected during the summer. These authors found differences related to rainfall, temperature and salinity in the community structure of tidal pools. Perennial algae, such as the corticated algae belonging to the phylum Rhodophyta, genera Gelidium, Solieria, Gracilaria and Hypnea, in addition to the filamentous red algae Centroceras and Ceramium, were observed at the study sites (Simões et al, 2009)
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