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Warming Enhances Reproduction of Intertidal New Zealand Crabs

Reference
Van den Brink, A.M., McLay, C.L., Hosie, A.M. and Dunnington, M.J. 2012. The effect of temperature on brood duration in three Halicarcinus species (Crustacea: Brachyura: Hymenosomatidae). Journal of the Marine Biological Association of the United Kingdom 92: 515-520.
Introducing their study, Van den Brink et al. (2012) say that "hymenosomatid crabs of the genus Halicarcinus have a reproductive strategy involving a terminal, pubertal moult where reproduction begins only when growth has ceased," which strategy "allows females to maximize their reproductive output during a comparatively short (approximately six month) adult life span by producing broods continuously and successively, without the need for the female to suspend reproduction for moulting," citing Van den Brink and McLay (2009, 2010). Against this backdrop, Van den Brink et al. investigated the effect of temperature on brood development for "three intertidal hymenosomatid crabs: Halicarcinus cookii, H. varius and H. innominatus," which they collected from intertidal habitats around the Kaikoura Peninsula of New Zealand that supported all three species.

Results of the analysis indicated that (1) "if temperatures rise 2°C as predicted, each of the three species could produce one extra brood per female lifetime," which they say "would result in the production of over 1000 extra larvae per female resulting in a 10-15% increase in fecundity" that could "result in a single female producing 10-50 extra surviving offspring per lifetime," that (2) "an increase in temperature is also likely to increase larval growth rates ... resulting in shorter development times," which "may also increase survival rates to final instars and eventually adults, thus potentially increasing the size of the population," and (3) "the current six month peak breeding season in the three Halicarcinus species may increase as temperatures rise," which "may allow the three Halicarcinus crabs more time to carry eggs and therefore produce even more offspring per lifetime." Given such findings, it would appear that global warming - if it ever gets going again - would prove extremely advantageous to the world's population of hymenosomatid crabs.

Additional References
Van den Brink, A.M. and McLay, C.L. 2009. The reproductive ecology and biology of the pillbox crab: Halicarcinus cookii (Brachyura: Hymenosomatidae) Filhol, 1885. MSc Thesis. University of Canterbury, Canterbury, New Zealand.

Van den Brink, A.M. and McLay, C.L. 2010. Competing for last place: mating behavior in a pill box crab. Halicarcinus cookii (Brachyura: Hymenosomatidae). Zoologischer Anzeiger 249: 21-32.

Archived 3 October 2012