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The interactions of numerous abiotic and biotic factors experienced by sea turtle embryos during incubation affect their survival. In this study we determined the hatching and emergence success of green turtles Chelonia mydas from nests on 4 beaches on the Galápagos Islands, one of the most important rookeries for green turtles in the eastern Pacific Ocean. Mean (± SD) hatching and emergence success for the 1039 nests examined were 46.0 ± 33.4 and 45.6 ± 33.4%, respectively. These values are relatively low compared to other green turtle populations worldwide. We evaluated the effects of beach, year, day of oviposition, carapace length and width of female, nest position, nest habitat, and nest chamber depth on hatching and emergence success with binomial generalized additive models with fixed effects. We found variation in hatching and emergence success was significant among beaches, years, day of oviposition, and nest habitat. Predation by feral pigs and beetles and destruction of earlier nests by nesting females were the most important causes of embryo mortality. Efforts to keep threats at minimum levels, particularly controlling pigs near Isabela beaches, should be considered a major conservation objective. This study highlights important differences among beaches within a rookery and emphasizes the need to continue improving management strategies to protect green turtles and their critical habitats. Quantitative information provided here can be used as a basis for long-term studies in the Galá-pagos and for comparison to other sea turtles rookeries. KEY WORDS: Chelonia mydas · Sea turtle reproduction · Clutch success · Generalized additive models · Pacific Ocean · Predation · Feral pigs · Beetles · ReptilesResale or republication not permitted without written consent of the publisher Aquat Biol 19: 217-229, 2013 cess refer to artificial hatchery operations (Hirth 1997) or experimentally manipulated clutches of eggs (Ackerman 1980) that may not reflect natural survival rates (Wyneken et al. 1988, Abella et al. 2007).Hatching and emergence success depends upon the interaction of numerous abiotic and biotic factors and varies among species and populations of sea turtles (Hirth 1980, Van Buskirk & Crowder 1994. Temperature (Matsuzawa et al. 2002, Segura & Cajade 2010, moisture (Ackerman 1980, Mortimer 1982, sand structure and composition (Mortimer 1990), and salinity (Ackerman 1980) can affect embryonic development by altering nest conditions. Hatching success can be affected by the nest location and its microhabitat or surrounding environment (Whitmore & Dutton 1985, Bjorndal & Bolten 1992, Hays & Speak man 1993. Human activities on nesting beaches resulting in sand compaction can decrease hatching and emergence success (Kudo et al. 2003). Predation of sea turtle eggs and hatchlings by a wide taxo nomic range of predators can have major effects; both native and introduced animals can substantially reduce hatching and emergence success (Stancyk 1982).Clutches deposited earlier in the season can subs...

Calyptogena gallardoi is a vesicomyid bivalve inhabiting a methane seep area located at a depth of 740–870 m off the Bay of Concepción, Chile. Vesicomyids host chemoautotrophic sulphide-oxidizing endosymbiont bacteria and are always found associated to reducing environments. In this study, the gonadal structure and the gametes produced by C. gallardoi are described. Light microscopy is used to examine serial histological sections of the gonads, and scanning electron microscopy is used to visualize the external morphology of gametes. The gonads of both males and females are organized in ramified tubular acini. In males, mature sperm are stored near genital openings in acini lined with a secretor epithelium that resembles a seminal receptacle. Spermatozoids have bullet-like heads with an average length of 30.3±2.6 μm (mean±1 SD). In females, the mature oocytes are driven toward the genital opening through evacuator conduits lined by ‘paddle’ cilia. The average diameter of oogonias is 11.6±2.5 μm and that of mature oocytes is 273.8±23.1 μm, making the size of the mature oocyte among the largest reported for bivalves. In addition, C. gallardoi is shown to have external sexual dimorphism. Shells of males are significantly smaller and more elongated with sloping postero-dorsal margin compared with shells of females. The data are discussed in the context of available information on reproductive biology of vesicomyids.