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

Abstract

Adult populations of the lithodid crab Paralomis spinosissima thrive at the lower temperature boundary of about 1°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°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.

Evidence for protracted and lecithotrophic larval development in the yeti crab Kiwa tyleri from hydrothermal vents of the East Scotia Ridge, Southern Ocean

“…The level of lecithotrophy observed in the first zoeal stage of K. tyleri is striking; with a C:N ratio ≥11.7, the level of lipid storage is exceptionally high, and higher than the C:N ratio (≥10.5) found in the lithodid Paralomis spinosissima from South Georgia waters, which held the previous lecithotrophy record in the Anomura (Thatje & Mestre 2010). In lithodid crabs, lecithotrophy is common and is associated with abbreviated larval development passing through 2 or 3 zoeal stages and a megalopa stage in Table 2.…”

“…The high level of lecithotrophy found in K. tyleri, and the lack of the zoeal stages typical of lecithotrophic larval development in the Lithodidae, may therefore indicate lecithotrophy continuing into juvenile stage(s). Indeed, in P. spinosissima from South Georgia waters, lecithotrophic development was found to exceed 14 mo in duration and under artificially high temperature conditions (5°C) experienced in laboratory cultures (Thatje & Mestre 2010). The level of lecithotrophy found in K. tyleri larvae developing in Southern Ocean temperatures (−1.3 to 0.5°C) should allow for food-independent development well beyond a year in duration.…”

“…Food independence and associated reduction in activity (little to no swimming), and demersal life of larvae have frequently been used as ecological features explaining the success of this group in cold waters, in particular in the Southern Ocean (for discussion, compare Lovrich 1999, Thatje et al 2005, Hall & Thatje 2011. Further, subtle but significant differences in the level of lecithotrophy have been identified among other species, indicating variations in the length of food independence as well as metabolic efficiency (Kattner et al 2003, Saborowski et al 2006, Thatje & Mestre 2010. The high level of lecithotrophy found in K. tyleri, and the lack of the zoeal stages typical of lecithotrophic larval development in the Lithodidae, may therefore indicate lecithotrophy continuing into juvenile stage(s).…”

“…The success of the anomuran lithodid crabs in most parts of the Southern Ocean where temperatures do not drop below approximately 0.5°C (Thatje et al 2008, Hall & Thatje 2011 has been attributed to hypometabolism and the optimisation of all life-history stages to low temperature. Optimisation includes larval lecithotrophy and slow development (Anger et al 2003, Katt ner et al 2003, Thatje et al 2005, Thatje & Mestre 2010.…”

Morfologia do esqueleto gástrico em Lithodidae Samouelle, 1819 (Crustacea: Decapoda:Anomura): implicações filogenéticas

“…E lecitotróficas em: Lithodes, Paralomis e possivelmente em Neolithodes (Anger 1996, Shirley & Zhou 1997, Watts et al 2006, Thatje & Mestre 2010. Esta última condição está sustentada pela redução das peças bucais observada nas larvas (Kattner et al 2003, Calcagno et al 2004).…”