MEPS 257:189-196 (2003)  -  doi:10.3354/meps257189

Changes in biomass and chemical composition during lecithotrophic larval development of the southern stone crab Paralomis granulosa

Javier A. Calcagno1,*, Sven Thatje2, Klaus Anger3, Gustavo A. Lovrich4, Antje Kaffenberger3

1Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Intendente Güiraldes 2160, Lab 64, 4
to Piso, Pab II, Cdad Universitaria C1428EHA, Buenos Aires, Argentina
2Alfred Wegener Institute for Polar and Marine Research, PO Box 120 161, 27515 Bremerhaven, Germany
3Biologische Anstalt Helgoland, Stiftung Alfred Wegener Institute for Polar and Marine Research, 27498 Helgoland, Germany
4Consejo Nacional de Investigaciones Científicas y Técnicas, Centro Austral de Investigaciones Científicas, CADIC, CC 92, V9410BFD Ushuaia, Tierra del Fuego, Argentina

ABSTRACT: Changes in biomass and elemental composition (dry mass, W; carbon, C; nitrogen, N; hydrogen, H) were studied in the laboratory during complete larval and early juvenile development of the southern stone crab Paralomis granulosa (Jacquinot). At 6 ± 0.5°C; total larval development from hatching to metamorphosis lasted ca. 56 d, comprising 2 demersal zoeal stages and a benthic megalopa, with mean stage durations of 5, 11 and 45 d, respectively. All larval stages of P. granulosa are lecithotrophic, and first feeding and growth were consistently observed immediately after metamorphosis to the first juvenile crab stage. Regardless of presence or absence of food, W, C, N, and H decreased throughout larval development. Also the C:N mass ratio decreased significantly, from 7.2 at hatching to 4.2 at metamorphosis, indicating that a large initial lipid store remaining from the egg yolk was gradually utilised as an internal energy source. In total, about 68% of the initial quantities of C and H present at hatching, and 44% of N were lost during non-feeding larval development to metamorphosis. Approximately 10% of the initially present C, N and H were lost with larval exuviae, half of which was lost in the megalopa stage alone. Hence, metabolic biomass degradation accounted for losses of ca. 59% in C and H, but for only 33% in N. Most of the losses in C and H reflected metabolic energy consumption (primarily lipid degradation), while ca. 1/4 of the losses in N and 2/3 of those in W were due to larval exuviation. Complete larval lecithotrophy is based on an enhanced maternal energy investment per offspring, and on energy-saving mechanisms such as low larval locomotory activity and low exuvial losses. These traits are interpreted as bioenergetic adaptations to food-limited conditions in subantarctic regions, where a pronounced seasonality limits the period of primary production.

KEY WORDS: Lecithotrophy · Cold adaptation · Larval development · Subantarctic · Crustacea · Decapoda

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