Environmental factors related to the production of a complex set of spicules in a tropical freshwater sponge.
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2015
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Adverse natural conditions will, generally, induce gemmulation in freshwater sponges. Because of this
environmental dependence, gemmoscleres are given exceptional value in taxonomic, ecological and
paleoenvironmental studies. Other spicules categories such as microscleres and beta megascleres have
received little attention with regard to their occurrence and function during the sponge biological cycle.
Metania spinata, a South American species common to bog waters in the Cerrado biome, produces alpha
and beta megascleres, microscleres and gemmoscleres. To detect the environmental factors triggering
the production of all these kinds of spicules, the species annual seasonal cycle was studied. Artificial
substrates were devised, supplied with gemmules and placed in Lagoa Verde pond which contained a
natural population of M. spinata. Field monitoring was conducted for eight months in order to observe
the growth of sponges and spicules formation. Samples of water were taken monthly for physical and
chemical parameters determination. The appearance of the alpha megascleres was sequentially followed
by that of microscleres, gemmoscleres and beta megascleres. The first ones built the new sponge skeleton,
the last three were involved in keeping inner moisture in the sponge body or its gemmules. The water
level, temperature and the silicon (Si) concentration in the pond were the most important factors related to
this sequential production of spicules, confirming environmental reconstructions based on the presence or
absence of alpha megascleres and gemmoscleres in past sediments.
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Field monitoring, Metania spinata, Spicules, Paleointerpretations
Citação
MATTEUZZO, M. C. et al. Environmental factors related to the production of a complex set of spicules in a tropical freshwater sponge. Anais da Academia Brasileira de Ciências, v. 87, p. 2013-2029, 2015. Disponível em: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000502013>. Acesso em: 25 ago. 2017.