Rasgos reproductivos de un cangrejo estuarino <i>Neohelice (</i>= <i>Chasmagnathus) granulata</i> (Brachyura: Grapsoidea: Varunidae) en dos hábitats contrastantes

Abstract

² Consejo nacional de investigaciones Científicas y Técnicas (CONICET) 3 Biologische anstalt Helgoland, Stiftung alfred-Wegener-institut für Polar-und meeresforschung, meeresstation, 27498 Helgoland, germany.SummarY: reproductive traits of an estuarine crab, Neohelice (= Chasmagnathus) granulata (dana 1851), were compared between individuals living in contrasting habitats (mudflat and saltmarsh) of the same population in the brackish coastal lagoon of mar Chiquita, argentina. in both habitats, most measures of egg biomass decreased during embryogenesis, including total dry weight (dW) and organic matter (measured as ash-free dry weight, aFdW) per egg, the contents of ash, carbon, hydrogen and nitrogen (per egg and as percentage values of dW), the energy content (estimated from C; both per egg and per mg dW), and the C/n and C/H mass ratios. Egg size, wet weight (WW), and water content (in µg and % of WW), by contrast, increased significantly during the time of embryonic development. These parameters reached significantly higher final (near-to-hatching) values in mudflats than in saltmarshes (egg volume 0.0249 vs 0.0233 mm 3 ; WW 36.5 vs 28.8 µg; water content 30.7 vs 23.2 µg per egg or 84.2 vs 80.2% of WW, respectively). Fecundity and reproductive effort did not differ significantly between habitats. Habitat-specific differences in the water content and size of crab eggs are discussed in relation to small-scale local variation in environmental conditions.Keywords: Neohelice, Chasmagnathus, estuary, fecundity, reproductive effort, egg volume, elemental composition (CHn).rESumEn: Rasgos reproductivos de un cangrejo estuarino Neohelice (= chasmagNathus) graNulata (Brachyura: Grapsoidea: Varunidae) en dos hábitats contrastantes. -los rasgos reproductivos del cangrejo estuarino, Neohelice (= Chasmagnathus) granulata, fueron comparados entre individuos que viven en hábitats contrastantes (planicie de marea y marisma) en una misma población de la laguna costera salobre de mar Chiquita, argentina. En ambos hábitats, la mayoría de las mediciones de biomasa de los huevos disminuyeron durante la embriogénesis, incluyendo el peso seco total (dW) y la materia orgánica (medida como peso seco libre de ceniza, aFdW) por huevo, el contenido de ceniza, carbón, hidrógeno y nitrógeno (por huevo y como valores porcentuales de dW), el contenido de energía (estimado a partir del C; por huevo y por mg dW), y la proporción de C/n y C/H. El tamaño del huevo, peso húmedo (WW), y contenido de agua (en % de WW), por el contrario, aumentaron significativamente durante el tiempo de desarrollo embrionario. Estos parámetros alcanzaron valores finales (cerca de la eclosión) significativamente más altos en la planicie de marea que en la marisma (volumen de los huevos 0.0249 vs 0.0233 mm 3 ; WW 36.5 vs 28.8 µg; contenido de agua 30.7 vs 23.2 µg por huevo y 84.2 80.2% WW; respectivamente). la fecundidad y el esfuerzo reproductivo no difieren significativamente entre ambos hábitats. las diferencias vinculadas al hábitat en el contenido de agua y ta...

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