Stone crabs (Menippe mercenaria) were reared in the laboratory to determine natural handedness. Claws of feral juvenile crabs were autotomized to test for reversal and to determine stridulatory pattern sequences. All crabs less than 4 mm carapace width were righthanded (side bearing the crusher claw). Eighty-eight percent of juvenile crabs with autotomized crushers showed signs of handedness reversal after the first regenerative molt. Stridulatory sequences indicated that a normal pattern was attained after two regenerative molts. Dockside claw surveys and trap sampling programs involving several Florida stone crab populations reveal an approximate 80:20 right:left-handed ratio in adult crabs through largest sizes trapped. This indicates that adults do not reverse as readily as juveniles.

The frequency of gonadal neoplasms in carp-goldfish hybrids was associated with the number of industrial outfalls to the Welland River. In a rural agricultural area without industrial discharges, upstream of the City of Welland, there were no observations of tumors in 1066 fish collected during the year-long study. In areas with moderate industrial loading, over ten percent of the carp-goldfish hybrids displayed gonadal neoplasms . In the section of the Welland River which received the largest quantities of municipal and industrial wastes neoplasm frequency in hybrids was 48% . Among sexually mature carp-goldfish hybrids, 80% displayed gonadal neoplasms in the most highly polluted portion of the Welland River .All neoplasms were confined to the gonadal tissues of adult hybrids, none were found in juvenile fish . The Fisher Exact Probability comparison of the frequency of neoplasms in adult carp-goldfish hybrids captured above and below the industrialized portion of the Welland River indicated that a significantly higher number of these fish with neoplasms occurred below the industrialized area (N = 13, p = 0 .035) .

No abstract

No abstract