AB 14:217-222 (2012)  -  DOI: https://doi.org/10.3354/ab00393

ABSTRACT: In 2009 Cartwright-Taylor et al. (2009; Aquat Biol 8:61–69) published a paper showing the monthly changes in population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda over a 1 yr period at the Mandai mud-flats at Kranji in Singapore. Although breeding is thought to be year-round, our work demonstrated that the proportion of juveniles in different size groups varied each month, with recruitment into the smallest size classes from November to March with a corresponding decrease in the proportion of adults, and into larger size classes from March to July coupled with an increasing proportion of adults, suggesting periods of high and low breeding activity through the year. Follow-up data, collected for a further 3 yr to determine if this pattern was maintained, indicate that this indeed is a feature of the population. Each January a high proportion of the small juveniles was found consistently in the population, while each July the population was dominated consistently by adults with some large juveniles. Mean incremental growth rate at ecdysis (36%) from a further 10 ind. confirmed growth rate findings in the first year. The male:female ratios also confirmed findings from the first year with little change from 1 in the sex ratios for the 3 follow-up yr, suggesting mating activity is not strongly seasonal, as occurs in temperate climates. Pairs in amplexus were seen year-round, but the numbers varied from month to month with no apparent seasonal pattern.

KEY WORDS: Mangrove horseshoe crabs · Carcinoscorpius rotundicauda · Breeding patterns · Population structure · Growth · Sex ratio

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Cite this article as: Cartwright-Taylor L, Hsu CC (2012) Follow-up study on population structure and breeding pattern of the mangrove horseshoe crab Carcinoscorpius rotundicauda in Singapore. Aquat Biol 14:217-222. https://doi.org/10.3354/ab00393 Export citation Share:    Facebook - - linkedIn