Life-history, movement, and habitat use of Scylla serrata (Decapoda, Portunidae): current knowledge and future challenges

Hilke Alberts-Hubatsch,Jan-Olaf Meynecke,Shing Yip Lee,Karen Diele,Matthias Wolff,Inga Nordhaus

doi:10.1007/s10750-015-2393-z

Abstract

The mud crab Scylla serrata is a highly exploited species, associated to mangrove ecosystems in the Indo-West-Pacific. It has a complex life cycle with a dispersing larvae phase, and benthic juveniles and adults. The former are stenohaline depending on high-salinity conditions to survive, whereas the latter are physiologically well adapted to changing temperatures and salinities, conditions that typically occur in mangrove habitats. Movement and habitat use of large juveniles and adults are well studied, and these life stages are known to utilize and move between various habitats within the mangrove ecosystem: intertidal flats as well as subtidal channels and flats. Females undertake long movements from brackish inshore waters to waters with oceanic conditions for spawning. Sensory abilities—of early stages and adult stages—have hardly been studied, and little is known about larval and early benthic stages in the wild. Summarizing, the literature revealed substantial gaps in the understanding of the spatiotemporal dynamics of the different life stages and of the clues that trigger recruitment, movement, and other behavior. This is the first comprehensive review on the life history, movement patterns, habitat use, and systemic role of S. serrata with emphasis on the respective life stages and geographic differences. We emphasize the need for further research into these processes as a basis for the sustainable management and conservation of this species.

Highlights

The highly valued mud crab Scylla serrata (Forskal, 1775) (Portunidae) is widely distributed throughout the Indo-West-Pacific (IWP) region (Keenan et al, 1998), where it is closely associated with mangrove forests
To avoid stating information that may relate to other Scylla species instead of S. serrata, we only considered publications from early years from study regions where this particular species is the only Scylla species known to occur, i.e., South-East Africa, southern East Australia, South Indo-Pacific Islands (‘‘Geographical distribution’’ section; Fig. 1; Appendix Table 1)
Throughout its life, S. serrata undergoes several ontogenetic shifts, expressing different behaviors and occupying different habitats at each stage (Fig. 2): I.) the larvae are released offshore, and undergo five larval stages before returning to coastal areas; II.) The larvae metamorphose into the megalopa stage in these coastal areas and subsequently settle and transform into the first juvenile stage in supposedly inshore areas; III.) Early juvenile mud crabs inhabit sheltered mangrove areas, and IV.) they expand their habitat to larger subtidal and intertidal areas in or adjacent to mangrove habitat when growing into an adult crabs

Summary

Introduction

The highly valued mud crab Scylla serrata (Forskal, 1775) (Portunidae) is widely distributed throughout the Indo-West-Pacific (IWP) region (Keenan et al, 1998), where it is closely associated with mangrove forests. The larvae have high dispersal potential during the planktonic life stages (16–75 days depending on environmental conditions, Baylon 2010), which is driven by regional and global currents This enables S. serrata to connect with other geographic areas and expand to new habitats, resulting in panmixis of the species (Hill, 1994; Gopurenko et al, 1999, 2003). Some authors (Quinn & Kojis, 1987; Robertson & Kruger, 1994) suggested that the different maturation sizes depend on the latitudinal distribution of the crabs, resulting in a faster maturation in tropical regions These conclusions might derive from the different size classes of the various Scylla species, since these assumptions were made before the revision of the species (see ‘‘Taxonomy’’ section). Perrine (1978) Quinn & Kojis (1987) Jayamanna & Jinadasa (1993) Hill (1994) Le Reste et al (1976) Delathiere (1990) Heasman (1980) Davis et al (2004) Robertson & Kruger (1994) Robertson (1996) Hill (1975) Du Plessis (1971)

Maturing III Mature

Fully mature

Findings

Conclusions and future challenges