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...

Chasmagnathus granulatus is a semiterrestrial intertidal burrowing crab that inhabits both the unvegetated mudflats and the cordgrass (Spartina densiflora) salt marshes in Mar Chiquita Lagoon (Argentina), where it is considered the ecologically key species. The mass of C. granulatus eggs incubated by females is colonized by epibiotic micro-organisms and accumulates detritus. The type of epibionts that use eggs as a substrate, the infestation degree, the maternal care behaviour and the protection of the incubation chamber were compared between females living on mudflats and on Spartina-dominated areas. In both places, the epibiosis by bacteria and filamentous fungi and peritrichid colonial ciliate was significantly higher in the periphery than in the centre of the brood mass. The accumulation of detritus was higher in the periphery in mudflat females but not in salt marsh females. Moreover, the level of detritus was significantly higher in mudflat than in salt marsh females only in the periphery of the brood. The infestation level of bacteria and fungi, and peritrichids, increased throughout the embryonic development only in mudflat females. The periphery of the brood mass was significantly more contaminated in mudflat than in marsh females, while the central region of the brood mass did not differ between habitats. The pleopods were significantly more contaminated by bacteria and filamentous fungi and peritrichid colonial ciliates in premoult females than in postmoult females, independently from the collection site. The percentage of females with abnormal embryos was significantly higher in mudflats (26.7%) than in marshes (12.3%). Females with late embryos spent more time flapping the abdomen and probing the embryos with the chela. Non-ovigerous females did not perform specific maternal care activities. The volume of brood mass both in early or late stage of development is greater than that of the incubation chamber and, consequently, peripheral embryos are more exposed.

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