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Helgol Mar Res (2008) 62:93102 DOI 10.1007/s10152-007-0076-5
ORIGINAL ARTICLE
Larval salinity tolerance of the South American salt-marsh crab, Neohelice (Chasmagnathus) granulata: physiological constraints to estuarine retention, export and reimmigration
Klaus Anger Eduardo Spivak Toms Luppi Claudia Bas Deborah Ismael
Received: 14 March 2007 / Revised: 17 July 2007 / Accepted: 17 July 2007 / Published online: 15 August 2007 Springer-Verlag and AWI 2007
Abstract The semiterrestrial crab Neohelice (=Chasmagnathus) granulata (Dana 1851) is a predominant species in brackish salt marshes, mangroves and estuaries. Its larvae are exported towards coastal marine waters. In order to estimate the limits of salinity tolerance constraining larval retention in estuarine habitats, we exposed in laboratory experiments freshly hatched zoeae to six diVerent salinities (532). At 5, the larvae survived for a maximum of 2 weeks, reaching only exceptionally the second zoeal stage, while 38% survived to the megalopa stage at 10. Shortest development and negligible mortality occurred at all higher salt concentrations. These observations show that the larvae of N. granulata can tolerate a retention in the mesohaline reaches of estuaries, with a lower limit of ca. 1015. Maximum survival at 25 suggests that polyha-line conditions rather than an export to oceanic waters are optimal for successful larval development of this species. In another experiment, we tested the capability of the last
zoeal stage (IV) for reimmigration from coastal marine into brackish waters. Stepwise reductions of salinity during this stage allowed for moulting to the megalopa at 410. Although survival was at these conditions reduced and development delayed, these results suggest that already the zoea-IV stage is able to initiate the reimmigration into estu-aries. After further salinity reduction, megalopae survived in this experiment for up to >3 weeks in freshwater, without moulting to juvenile crabs. In a similar experiment starting from the megalopa stage, successful metamorphosis occurred at 410, and juvenile growth continued in freshwater. Although these juvenile crabs showed signiWcantly enhanced mortality and smaller carapace width compared to a seawater control, our results show that the late larval and early juvenile stages of N. granulata are well adapted for successful recruitment in brackish and even limnetic habitats.
Keywords Larval development Crab Varunidae Export strategy Salinity stress
Ontogeny of osmoregulation Estuarine Recruitment
Introduction
The varunid crab Neohelice granulata (Dana 1851)...