Convergence of trophic state and the lower food web in Lakes Huron, Michigan and Superior

Congruent energy density trends of fish and birds reflect ecosystem change

“…The biomass of Lake Huron phytoplankton and zooplankton communities declined , 50% from 1999-2006, with water clarity doubling over the time frame of the current study (Barbiero et al 2012). Reduced abundances of benthic invertebrate species, including chironomids, oligochaetes, sphaerid mussels, and the benthic amphipod Diporeia spp., have also occurred during the establishment of dreissenid mussels in Lake Huron (Nalepa et al 2007;Barbiero et al 2011).…”

“…Decreased pelagic production potentially reinforces bottom-up controls, resulting in oligotrophication, particularly in upper-trophic-level organisms which rely primarily on offshore pelagic production. Recent evidence has demonstrated the increasing oligotrophication of Lake Huron during a period that is consistent with the establishment and expansion of dreissenid biomass in this lake (Barbiero et al 2012). Ecological indicators including zooplankton biomass and community composition for Lake Huron's lower food web are currently consistent with those for Lake Superior (Barbiero et al 2012).…”

“…Recent evidence has demonstrated the increasing oligotrophication of Lake Huron during a period that is consistent with the establishment and expansion of dreissenid biomass in this lake (Barbiero et al 2012). Ecological indicators including zooplankton biomass and community composition for Lake Huron's lower food web are currently consistent with those for Lake Superior (Barbiero et al 2012). Specifically, Lake Huron zooplankton populations have become dominated by oligotrophic indicator species Limnocalanus macrurus and Conochilus spp., with total zooplankton biomass estimates averaging , 60% of those reported for Lake Superior (Barbiero et al 2012).…”

“…90 m demonstrating that the population continued to expand throughout the basin (Riley 2013). During this expansion, main basin open-water total P concentrations also declined , 3-fold (Barbiero et al 2012). That such oligotrophication of Lake Huron's pelagia was concordant with increased dreissenid abundances and their expansion into deeper offshore waters confirms a key prediction of the NSS (Hecky et al 2004).…”

A science plan for carbon cycle research in North American coastal waters. Report of the Coastal CARbon Synthesis (CCARS) community workshop, August 19-21, 2014

“…Reductions in phosphorus inputs have also been linked to increases in nitrate (Finlay et al, 2013). The invasive Dreissenid mussels have caused measurable drops in calcium and alkalinity due to shell burial in Lakes Erie and Michigan (Barbiero et al, 2012). A complex interplay of climate change, agricultural practices, and invasive species is thought to be responsible for the re-eutrophication of Lake Erie and associated increases in the extent of hypoxia (e.g., Kane et al, 2014;Zhou et al, 2013).…”