Population dynamics and secondary production of crabs in a Chinese salt marsh

Abstract

In many salt marsh ecosystems, crabs are the most prominent members of the macrobenthic community, influencing material cycling and energy flow. Studies on population dynamics and secondary production are important for quantitative evaluation of the ecological function of crabs; however, few studies have been conducted in salt marsh ecosystems. In this study, we investigated the secondary production and population dynamics of two Thoracotremata species in an Asian salt marsh. A year-round sampling on a monthly basis in the Dongtan salt marshes of the Yangtze River estuary yielded 12 species of crabs belonging to 7 families and 10 genera. The dominant crabs were Chiromantes dehaani (67.57%) and Hélice tientsinensis (17.28%). The overall size frequency distribution was bimodal for C. dehaani and unimodal for H. tientsinensis. The estimated annual production of C. dehaani and H. tientsinensis was 43.981 g and 4.247 g ash-free dry weight (AFDM) m~^ year" ', respectively. The annual P/B ratio was 1.22 for C. dehaani and 0.75 for H. tientsinensis. In total, the annual secondary production of all crabs at the Dongtan salt marshes was estimated to be approximately 49.405 g AFDM m"^ year" '. The consumption of vascular plants by C. dehaani and H. denLnnensis was 480.831 and 42.640 g AFDM m"^ year"'. About 20.4% of plant primary production was ingested by these two herbivorous crabs. The production of C. dehaani was high compared with those reported from other coastal wetland ecosystems. This suggests that the ecological functions of C. dehaani at the Yangtze River estuary salt marshes need more quantitative studies to be fully described. RÉSUMÉDans de nombreux écosystèmes lagunaires, les crabes sont les représentants les plus dominants de la communauté macro benthique, influençant le cycle de matériaux et le flux d'énergie. Les études en dynamique des populations et production secondaire sont importantes afin de quantifier la fonction écologique des crabes ; cependant, peu d'études ont porté sur les écosystèmes lagunaires. Dans cette étude nous avons investigué la production secondaire et la dynamique des populations de deux espèces Thoracotremata dans des lagunes asiatiques. Des échantillonnages mensuels pendant toute une année dans les lagunes de Dongtan de l'estuaire de la rivière Yangtze ont fourni 12 espèces de ')

Life history and stable regeneration of the endangered saltmarsh sesarmid crab Clistocoeloma sinense in small populations of the isolated metapopulation of Tokyo Bay, Japan

“…3). The longevity of other grapsid species inhabiting intertidal saltmarshes in west Pacific Ocean estuaries ranges from 2 to 4 years: 2-3 years for Parasesarma pictum in Hong Kong (Yau 1992); 3-4 years for Parasesarma affine in Hong Kong (reported as P. plicatum in Kowk 1995); 3-4 years for Perisesarma bidens in Hong Kong (Kwok 1995); and 3.0-3.8 years for Chiromantes dehaani and Helice tientsinensis in the Yangtze River Estuary, China (Chu et al 2013). These data suggest that C. sinense has similar longevity to other saltmarsh grapsid crabs in northwest Pacific estuaries.…”

Dietary preferences of brachyuran crabs from Taiwan for marine or terrestrial food sources: evidence based on fatty acid trophic markers

“…It feeds primarily on filamentous green algae like Ulva spp., but it opportunistically includes carrion in its diet [6,17]. The semi-terrestrial Orisarma intermedium (formerly Sesarmops intermedius) occurs along coastal rivers, estuaries, and in salt marshes [18,19]. It feeds on grass and fresh or old leaf litter [19] (Hung-Chang Liu, pers.…”

“…The semi-terrestrial Orisarma intermedium (formerly Sesarmops intermedius) occurs along coastal rivers, estuaries, and in salt marshes [18,19]. It feeds on grass and fresh or old leaf litter [19] (Hung-Chang Liu, pers. obs.).…”