Taxa de crescimento e produção de CaCO3 de rodolitos na costa semiárida brasileira

Abstract

Rodoliths are free-living structures formed by non-articulated coralline red algae. These organisms have great importance in the carbon cycle, as they can stock carbon in the form of calcium carbonate (CaCO3). In addition, a wide range of associated organisms can shelter in rhodolith beds due to their structural complexity. The present research reported the growth rate of these algae as well as the calcium carbonate production rate of a rhodolith bed in an area of the internal continental shelf of the Brazil's semiarid coast. The red Alizarin tagging method was applied and after 7 months a growth rate of 2.46 ± 0.19 mm.year-1 was observed, a higher value than in low latitudes, which has colder waters. In addition, the Mann-Whitney test revealed a significant difference (p <0.05) between the growth rate of different growth patterns. The carbonate production rate was 99.36 ± 3.45 g.m-2.year-1, a lower production than in other latitudes due to the small number of rhodolites per m² found on the site. After comparing the results obtained and data extracted from a systematic literature review, it was observed that the growth rates of calcareous algae grow towards the equator line. This work can serve as a basis for quantitative studies on the production of biogenic carbonates in the oceans and for studies on the responses of these organisms to environmental changes.