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.

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

Mangrove carbon sink. Do burrowing crabs contribute to sediment carbon storage? Evidence from a Kenyan mangrove system

Anthropogenic organic contaminants in water, sediments and benthic organisms of the mangrove-fringed Segara Anakan Lagoon, Java, Indonesia

Food preferences of mangrove crabs related to leaf nitrogen compounds in the Segara Anakan Lagoon, Java, Indonesia

Rich soil carbon and nitrogen but low atmospheric greenhouse gas fluxes from North Sulawesi mangrove swamps in Indonesia

The benthic macrofauna of the Segara Anakan lagoon, Java, Indonesia and its fringing mangroves were investigated between May 2004 and August 2006. This lagoon has been affected by various human activities for decades, in particular fishing, effluents from agriculture and industry, and illegal deforestation. In total, 163 taxa were identified, including 127 species occurring in the mangrove forest and 59 species in the subtidal. Mean density of macrobenthos was 2.5-fold higher in the central (881.8 ± 1,151.3 ind. m−2) than in the eastern mangrove site (356.3 ± 218.8 ind. m−2). Community structures differed significantly between these sites and showed a serial shift during the investigation period. Gastropods dominated the community in the central mangrove location, whereas sipunculids, polychaetes and gastropods had similar densities in the eastern site. Differences in community composition were best explained by three sediment properties: pore water salinity, δ13Corg, and Corg/N. It is suggested that small-scale heterogeneity of food availability and quality is a main factor determining the small-scale variability of the community composition. Compared to other Indo-West Pacific mangroves, species richness and densities are high. However, the dominance of specific taxa, especially of opportunistic species and the comparably low species richness in the subtidal of the lagoon may be attributed to the high sediment input by rivers in the central part and to the large-scale cutting of mangroves. Continuous tree logging will probably lead to a further spread of two fast growing understorey plants and thus to an increase of uniform swamp sites and a decrease of micro-habitats for benthic macrofauna. To our knowledge, this is the first detailed study on the spatio-temporal variation of benthic macrofauna in mangroves of Indonesia.

Spatio-temporal variation of macrobenthic communities in the mangrove-fringed Segara Anakan lagoon, Indonesia, affected by anthropogenic activities

The carnivorous gastropod Xandarovula patula is a species being known to mainly occur west and south-west of the UK, down to the Atlantic coast of Spain. It also was recently reported from the central parts and the periphery of the North Sea, up to Trondheim (Norway). Now, it was also recorded during a survey of the epibenthic faunal composition from the Dogger Bank in winter 2011. The collecting stations are located on a routine station on the western Dogger Bank at a depth average of 25 m, as well as off the south-western edge of the Dogger Bank at a mean depth of 65 m. The bottom of both stations is covered with sparse boulders and rubble with a dense cover of Alcyonium digitatum, the preferred food of Xandarovula patula. This is another example for the spreading of oceanic ‘warm water’ species towards the central North Sea along the main, northern currents. The present work summarizes all records of X. patula from the North Sea available in the literature up-to-date and verifies rising water temperatures at the main area of recent records at the Dogger Bank, possibly promoting the species' spreading.

Ronald Janssen

Papers

Spatio-temporal variation of macrobenthic communities in the mangrove-fringed Segara Anakan lagoon, Indonesia, affected by anthropogenic activities

Recent spreading of Xandarovula patula (Mollusca: Gastropoda: Ovulidae) towards the central North Sea suggests a link to rising water temperatures