First discovered in San Francisco Bay in 1992, the Chinese mitten crab, Eriocheir sinensis, has become established over hundreds of km 2 of the San Francisco Estuary. Ecological and economic impacts of this invasive species motivated our search for a greater understanding of the crab's life history as an important step in better management and control. Data for this life history model comes from the authors' research and scientific literature. Juvenile crabs migrate from the Estuary into fresh water where they develop into adults. Environmental signals may stimulate gonad development that is followed by a downstream migration beginning at the end of summer. Mating occurs after the crabs reach saline water. Embryos are carried until hatching, and the larvae undergo five zoeal stages before settlement. Our model projects rates of development at various temperatures and growth increments, supports a minimum of 2 years in low salinity or freshwater habitat, and predicts that most California mitten crabs are at least 3 years old before becoming sexually mature. Environmental factors strongly influence the timing and duration of the crab's life stages, and are discussed in the context of a gradient of development times for worldwide populations of this important invasive species.

The digestive tract pH values of the teleost fish Oreochromis mossamhicus, Carassius uuratus and Ictalurus punctutus were determined in fish that were (1) starved, (2) fed herbivorous, omnivorous and carnivorous diets and (3) fed altered pH diets. The digestive tract pH profile was determined throughout an 8 h cycle. The herbivorous or carnivorous nature of the diet did not affect the pH values in any of the species. Significant differences in gut pH values were observed when the fish ingested diets with altered pHs. There was a difference between the starved and baseline fed values in Carassius auratus which was not observed in the other species. The pH values in the digestive tracts of the three species varied during the digestive cycle.

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