Long-term dynamics of larval and early juvenile spot (Leiostomus xanthurus) off the U.S. East Coast: relating ocean origins, estuarine ingress, and changing environmental conditions

Ichthyoplankton data sets based on collections from estuaries in South Carolina, North Carolina, Virginia, Delaware, and New Jersey and from ocean cruises off the U.S. East Coast were examined to determine spawning locations in the ocean, cross-shelf distributions of larvae, and movements of spot (Leiostomus xanthurus) into estuaries.Spot spawn during fall and winter near the edge of the continental shelf, primarily south of Cape Hatteras in North Carolina.We documented additional spawning of spot north of Cape Hatteras, close to the coast, in summer and fall.Larval and early juvenile spot enter estuaries from November through May in South Carolina and North Carolina and from January through June in Virginia, Delaware, and New Jersey.Numbers of spot per volume of water sampled decreased from south to north among estuaries and in the ocean.Interannual variations in abundance were high, and no long-term trends were determined.Over the decades, median annual lengths of ingressing larval and juvenile spot decreased as annual mean water temperature increased in South Carolina and North Carolina.The timing of ingress was positively correlated with water temperature.Continued increases in water temperature on the East Coast will likely lead to additional changes in oceanic distribution and ingress patterns of spot.Our findings indicate the value of synthesizing information from long-term studies conducted across broad geographic scales.