Phenology of an agarophyte Gracilaria birdiae Plastino and E.C. Oliveira (Gracilariales, Rhodophyta) in Northeastern Brazil

Abstract

Abstract:The reproductive phenology and thallus length of Gracilaria birdiae were studied over a period of 12 months in a natural bed in Northeastern Brazil. Fertile specimens of G. birdiae were observed during the entire study period. Tetrasporophytes were the most common with an annual mean of 80.1±5.6%, followed by cystocarpic plants (9.3±3.4%), male gametophytes (8.3±3.6%) and infertile plants (2.2±3.4%). Only male gametophytes and infertile plants showed a variation in occurrence frequency during the year (p<0.05). With respect to thallus length, a distinct seasonal variation was observed for all reproductive stages (p<0.05), with the highest values recorded during the rainy season (March to August) and the lowest in the dry season (September to February). The results demonstrate that the size of individuals in this population is significantly affected by the periodic changes in the environment caused by rainfall regimes and hydrodynamism.

Effects of light quality on reproduction, growth and pigment content of <em>Gracilaria birdiae</em> (Rhodophyta: Gracilariales)

“…Otherwise, cystocarps and spermatangial conceptacles were not differentiated in sufficient amounts to promote the decrease of GRT, and their differentiation could not be related to any specific wavelength. The higher fertility of tetrasporophytes in comparison with gametophytes agrees with the phenology of G. birdiae (Carneiro et al 2011). Moreover, tetrasporophytes were much more abundant and efficient at occupying environmental niches than gametophytes, indicating a greater ability to respond to environmental signals as inductors of fertility, in turn resulting in higher propagation of the species.…”

“…Thus, the photoperiod can influence reproductive status of tetrasporophytic thalli, even if not exposed exactly to 8L:16D in nature. Under these circumstances, the photoperiod could explain the frequency variation of reproductive stages observed in natural populations of G. birdiae by Carneiro et al (2011). These authors observed higher tetrasporophyte percentages during the winter months when photoperiods are shorter than in summer months.…”

“…Oliveira has shown higher potential for agar extraction, although only natural banks have been exploited (Plastino and Oliveira 2002). The species has been harvested in northeast Brazil near coastal communities, and the short time interval between one harvest and the next is not sufficient to permit the complete recovery of seaweed beds (Carneiro et al 2011). This species occurs from the northeast (3°S) to the southeast (20°S) coast of Brazil (Plastino and Oliveira 2002), and its extreme populations are in geographical areas 2500 km apart.…”

“…This species occurs from the northeast (3°S) to the southeast (20°S) coast of Brazil (Plastino and Oliveira 2002), and its extreme populations are in geographical areas 2500 km apart. Fertility is commonly observed, with abundance of tetrasporophytes in comparison with gametophytes (Carneiro et al 2011). Considering its geographic distribution and daily photoperiods (Brazilian National Institute for Space Research, http:// sonda.ccst.inpe.br/basedados/index.html), G. birdiae may be exposed to photoperiods ranging from 10.8 to 13.9 h in the winter and summer solstice, respectively.…”

Seaweed Production Potential in the Brazilian Northeast: A Study on the Eastern Coast of the State of Rio Grande do Norte, RN, Brazil

“…In Brazil, marine seaweed occurs along the coast, but is more diverse and abundant in the northeast. The seaweed exuberance in this region is mainly related to favorable temperatures, salinities and light conditions, as well as rocky substrates and suitable reefs for their establishment and growth [10,34].…”