Potential invasive species impacts on prey availability and foraging by larval yellow perch and alewife in the near-shore zone of southeastern Lake Michigan

Jonah L Withers, Purdue University

Abstract

Yellow perch (Perca flavescens) and alewife (Alosa pseudoharengus) are ecologically and economically important species in Lake Michigan; however, despite their significance, mechanisms controlling early life survival and subsequent recruitment of both species remain elusive. Though many recent studies have focused on the off-shore region, the near-shore region is where larval yellow perch and alewife spawn and, presumably, begin exogenously feeding. The transition between endogenous and exogenous feeding is thought to be a critical-period in which prey type, size, and density can influence larval survival. Along with larval yellow perch and larval alewife, three species of predatory zooplankton, Leptodora kindtii (native), Bythotrephes longimanus (invasive), and Cercopagis pengoi (invasive), inhabit the near-shore areas of Lake Michigan. While these predatory zooplankton are hypothesized to compete with larval fish, the potential for competition may be limited by spatiotemporal overlap, consumptive demand, and prey densities. We examined spatiotemporal distributions of larval yellow perch, larval alewife, predatory zooplankton, and their potential prey within near-shore Lake Michigan and quantified biotic and abiotic factors influencing their distributions. We sampled biotic and measured abiotic conditions along a southeastern Lake Michigan transect on every third to fourth day between May 5 to July 20 in 2010 and once a week between May 21 and July 18 in 2011. Trends within species were similar between sampling years; however, biota emerged and reached peak densities earlier in the season during 2010 than 2011 presumably due to earlier warming. The severity of temporal overlap of larval fish and predatory zooplankters appears to be influenced by early warming. Despite predatory zooplankton densities peaking later in the season, Leptodora and Cercopagis densities and daily consumption were generally greater than larval fish. Therefore, we believe Cercopagis and Leptodora have the greatest potential to compete with larval fish for resources within the near-shore region. Interestingly, first-feeding larval fish preyed upon smaller items; such as diatoms and dreissenid mussel veligers, suggesting they may be gape-limited and preferred prey may be limited. Effects of ingesting such prey items are largely unexplored. Future research should examine the effects of dreissenid mussel veliger and diatom ingestion by first-feeding larval fish and further elucidate Cercopagis and Leptodora resource exploitation within the near-shore region on Lake Michigan.

Degree

M.S.

Advisors

Hook, Purdue University.

Subject Area

Aquatic sciences

COinS