Tidal exchange of larvae of Sesarma catenata (Decapoda, Brachyura) in the Swartkops estuary, South Africa

The tidal exchange of larvae of the salt-marsh grapsid crab Sesarma catenata was studied in the Swartkops estuary, a tidally driven, shallow estuary in Algoa Bay, South Africa. Plankton samples were collected bimonlhly during spring and neap tides from October to March at the tidal inlet. Samples were collected hourly for 25 h in February, and for 13 h in all other months. Hourly estimates of water flux through the tidal inlet of lhe esluary were calculaled using a generalized one-dimensional hydrodynamic model calibrated for lhe Swartkops estuary. Water flux estimates were used to calculate larval flux through the tidal inlet, Zoea I larvae of Sesarma catenata were found in all sampling sessions, with highest abundance during nocturnal ebb tides. Two seasonal peaks of abundance were detected in November and February-March. These coincided with recorded peaks of percentage abundance of gravid females in the adult population. Megalopa larvae were recorded mainly during flood tides from January to March. More than 70 % of all Sesarma catenata larvae moving through the tidal inlet of the Swartkops estuary in either direction were exported in any given sampling session. There was net export of zoea l larvae in all cases but one, and net import of megalopa larvae in all cases. The possibility that Sesarma catenata larvae may become entrapped in lhe surf zone circulation system throughout development, as a mechanism to avoid offshore dispersal, is discussed

Larval development of Sesarma catenata Ortmann (Brachyura, Grapsidae, Sesarminae) reared in the laboratory

Sesarma catenata larvae were raised in the laboratory and the development stages described in detail. larval development comprises four zoea and one megalopa stage. Morphological features of the first zoea and megalopa stages of Sesarma catenata are compared with those of other Sesarminae species described in the literature. The genera Sesarma, Metasesarma, and Bresedium appear to be closely related taxa within the subfamily. The diagnostic value of some features of larval morphology is briefly discussed.S. Afr. J. Zool.1987, 22(3

The zoeal development of Sesarma eulimene de Man (Decapoda, Brachyura, Grapsidae), and identification of larvae of the genus Sesarma in South African waters

The five zoea larval stages of the estuarinecrab Sesarma eulimene de Man 1897 (Brachyura, Grapsidae) are described in detail from specimens reared in the laboratory. The morphology of larval Grapsidae is briefly discussed and an updated summary of larval diagnostic characters in the genus Sesarma is given as an aid to identifying specimens in plankton samples from Soulh African waters

The larval development of the red mangrove crab Sesarma meinerti de man (Brachyura: Grapsidae) reared in the laborator

The larval stages of the red mangrove crab Sesarma meinerti de Man were reared in the laboratory. Larval development consists of five zoeal stages and one megalopa. Zoeal development lasts an average of 25 days at 25°C. The external morphology of larvae is described in detail and their relationship with larvae of congeneric species is briefly discussed

Article Phototactic behaviour and the nature of the shadow response in larvae of the estuarine crab Sesarma catenata

The phototactic behaviour of the first zoea of the estuarine crab Sesarma catenata (Brachyura, Grapsidae) was studied in the laboratory. Light and dark-adapted larvae showed only positive phototaxis when stimulated horizontally with light intensities ranging from 10-7 W m-2 to 1 W m. Peak percentage response was at 10-1 W m-2 and 10-4 to 10-2 W m-2 in light and dark-adapted larvae respectively. This pattern differs from that common to other brachyuran larvae in the absence of negative phototaxis at low light intensities in light-adapted larvae. The shadow response in S. catenata first zoea was studied in a natural light field. The nature of the shadow response is discussed according to larval responses in the horizontal plane. An interpretation of the mechanics of the shadow response is proposed which does not involve negative phototaxis. The consequences of the phototactic behaviour of larvae for dispersal in the Swartkops estuary are briefly discussed. According to their phototactic pattern, larvae would migrate to the top section of the water column and aggregate there during the day. This would increase their chances of being exported out of the estuary with the ebb tides

DNA barcoding for species assignment: the case of Mediterranean marine fishes

DNA barcoding enhances the prospects for species-level identifications globally using a standardized and authenticated DNA-based approach. Reference libraries comprising validated DNA barcodes (COI) constitute robust datasets for testing query sequences, providing considerable utility to identify marine fish and other organisms. Here we test the feasibility of using DNA barcoding to assign species to tissue samples from fish collected in the central Mediterranean Sea, a major contributor to the European marine ichthyofaunal diversity.Research carried out at University of Palermo was supported by "Fondi di Ateneo ex 60% Universita di Palermo". This work was supported by FEDER through POFCCOMPETE and by national funds from "Fundacaopara a Ciencia e a Tecnologia (FCT)" in the scope of the grants, FCOMP-01-0124-FEDER-010596 and PEst-OE/BIA/UI4050/2014. ML's work was supported by the fellowship Ref: SFRH/BPD/45246/2008 from Fundacaopara a Ciencia e a Tecnologia. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript