Energetic changes throughout lecithotrophic larval development in the deep-sea lithodid crab Paralomis spinosissima from the Southern Ocean

Adult populations of the lithodid crab Paralomis spinosissima thrive at the lower temperature boundary of about 1 degrees C for the Lithodidae, and are endemic to deep waters off South Georgia, Southern Ocean. Here, we present evidence for lecithotrophic development throughout the early ontogeny of this species over a period of 14 months. At constant 5 degrees C (+/-0.5), development of the Zoea I and II, the megalopa, and the crab I instar lasted about 12, 24, 108, and 290 days, respectively. Successful development and moult at lower temperatures could not be observed. Changes in biomass and elemental composition (W, C, and N) were studied throughout larval and early megalopa development. Initial biomass was about twice as high as in lecithotrophic larval developments previously reported for subantarctic lithodids, and only a minimal shift (9.2 to 8.9) in C:N mass ratio was observed from the Zoea I to the megalopa stage; at the same time an even decrease of both C and N indicated no bias toward the depletion of lipids. Very thin exuviae cast at moult support the view of energy-saving adaptations throughout larval development. The cost of higher maternal investment into single offspring and the lack of evidence for successful larval development at temperatures typical of Southern Ocean deep waters, pose questions with regard to the frequency of successful recruitment events of lithodid crabs at their lower physiological temperature tolerance. Significant intraspecific variability in larval energetic fitness at hatching between females, suggesting variability in offspring fitness, may additionally constrain on offspring survival. (C) 2010 Elsevier B.V. All rights reserved.