RHITHROPANOPEUS-HARRISII (GOULD), AN AMERICAN CRAB IN THE ESTUARY OF THE MONDEGO-RIVER, PORTUGAL

The estuarine crab Rhithropanopeus harrisii (Gould) was originally fou nd along the North American Atlantic coast and in 1991 was reported fo r the first time on the Iberian Peninsula. The larvae of this species were found only in the upper reaches of the Mondego estuary, Portugal, during spring and summer months, from late April to September. Larval density was highest during June. The reproductive season of R. harris ii occurs within the range of the highest water temperature. This stud y shows a temporal coherence in the larval patterns of occurrence duri ng 2 years of sampling, and indicates that larvae of R. harrisii are m ore abundant near the surface during night flood tide, but near the bo ttom during ebb tide. This suggests a net larval landward transport, w hich results in retention near the area of adult spawning. The aim of this study was to analyze the seasonal and spatial occurrence and tida l abundance of larvae of R. harrisii in the estuary of the Mondego riv er, Portugal. In addition, patterns of the temporal distribution of th e larvae on the geographic range where the crab larvae have been found are briefly reviewed.