Migration patterns, densities, and growth of Neritina punctulata snails in Rio Espiritu Santo and Rio Mameyes, northeastern Puerto Rico

ABSTRACT.—Snail size-frequency distributions in Rios Espiritu Santo and Mameyes, which drain the Luquillo Experimental Forest, Puerto Rico, showed that Neritina punctulata with shell lengths greater than 30 mm were the most abundant size class at upstream sites. The highest densities for all size classes were at the downstream sites. Growth rates were 0.015 mm/day for a large cohort (∼ 25 mm shell length) and 0.035 mm/day for a small (∼ 15 mm shell length). Minimum longevity estimates range from 3 to 7 years. Size distribution data ...