Fecundity and reproductive patterns of the fiddler crab Uca maracoani Latreille 1802-1803 in an Amazonian estuary in northern Brazil

ABSTRACT In this study, aspects of the reproductive biology of a Uca maracoani population from northern Brazil were examined. Ovigerous females monthly captured from December 2013 to November 2015 were measured and dissected to count, collect morphometric data, and classify the eggs. Ovigerous females were encountered throughout the two-year period but were absent during the months with the highest rainfall and lowest salinity, which indicates a seasonal–continuous reproductive pattern. The fecundity varied from of 12,233 to 85,000 eggs per female, and mean was 36,840 ± 3,361 eggs. The egg size increased progressively and significantly over the course of embryonic development. We found a direct relationship between the size of the females and their fecundity, and a clear trend was seen in which the larger females produced more eggs with larger sizes, which increased less in size during embryonic development. The presence of early- and late-stage eggs together in the same ovigerous mass in a considerable number of the ovigerous females suggests multiple spawning. The fecundity of U. maracoani is greater than that of other Atlantic fiddler crab species, and its reproductive strategy ensures its survival in the estuaries of the Amazon coast, which are subject to considerable fluctuations in salinity.