Intensified environmental and density-dependent regulation of white perch recruitment after an ecosystem shift in the Hudson River Estuary

Long-term monitoring data were used to test whether the invasion of zebra mussels in the Hudson River Estuary (HRE) in 1991 altered the influence of density-dependence and environmental conditions on life-stage transitions, growth and partial migration in white perch (Morone americana). During the post-invasion period (1992-2013), we estimated standing stocks of white perch eggs, yolk-sac larvae (YSL), post yolk-sac larvae (PYSL), young-of-the-year (YOY) and adults, as well as indices of YOY growth and spatial distribution. A series of linear and nonlinear functions were employed to model life-stage transitions, while the effects of six environmental and density-dependent variables on YOY growth and partial migration were quantified. Comparisons to pre-invasion observations (1974-1991), indicated that egg-YSL, PYSL-YOY and YOY-yearling transitions changed significantly after the invasion, while PYSL abundance developed a stronger negative effect on YOY growth. The PYSL-YOY transition became more sensitive to density-dependence and freshwater flow from 1992-2013, which is consistent with diminished abundance and increased environmental sensitivity of the forage base in the HRE reported after the zebra mussel invasion.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author