Coastal Sediment Dynamics and River Discharge as Key Factors Influencing Coastal Ecosystem Productivity in Southeastern Lake Michigan

Approaching storm: Disappearing winter bloom in Lake Michigan

“…Detailed inspection of river discharges and resuspended sediments along the southeastern coastline of Lake Michigan (Biddanda and Cotner, 2002) suggested high levels of dissolved organic matter and enhancement of productivity along the coastal shelf in years when the nearcoastal turbidity plume did not hinder photosynthesis (Millie et al, 2002;Lohrenz et al, 2004Lohrenz et al, , 2008. Here we extended the initial Lake Michigan observations to a number of the Laurentian Great Lakes.…”

“…Primary production estimates in 1998 ranged from 0.18 to 0.48 g C/m 2 /d compared to 0.18-0.24 g C/m 2 /d for satellite-derived values, and in 2000 ship-board studies gave 0.19-0.37 g C/m 2 /d compared to 0.15-0.46 g C/m 2 /d for satellite-derived values (Lohrenz et al, , 2008. Recent offshore Muskegon site estimates suggest a 66% decline in spring Chl a and a 70% reduction in productivity , whereas GLNPO April ship surveys show about a 72% decrease in April Chl a concentrations in southern Lake Michigan (Mida et al, 2010).…”

“…The logarithmic fit was heuristic for it covered saturating values in nearshore turbidity plumes, while revealing subtle patterns for low-concentration levels in offshore waters. Further discussion of validations used with SeaWiFS imagery during the EEGLE project can be found in Bergmann et al (2004) and Lohrenz et al (2008). Bergmann et al (2004) discuss difficulties in OC2 Chl a determinations relating to marine versus freshwater phytoplankton species differences.…”

“…Bergmann et al (2004) discuss difficulties in OC2 Chl a determinations relating to marine versus freshwater phytoplankton species differences. Additional water column calibrations between CTD fluorometry and Chl a are discussed in Vanderploeg et al (2007) and Lohrenz et al (2008).…”

An algorithm to retrieve chlorophyll, dissolved organic carbon, and suspended minerals from Great Lakes satellite data

“…However, Bergmann et al found that in Lake Michigan there were statistically significant deviations between in situ measured and OC3 modeled chlorophyll concentrations when cryptophytes make up a large percentage (N40%) of the total chlorophyll (Bergmann et al, 2004) indicating potential limitations of ratio based methods to produce accurate chlorophyll retrievals in dynamic phytoplankton regimes. In areas of the Great lakes such as the near shore and bays where the observed color is a result of chl, cdom and sm the OC3 retrieval values are overestimated, a consequence of the band ratio approach assuming a single CPA component, namely phytoplankton (Lohrenz et al, 2008). The high shallow water chl concentrations provided by the OC3 blue-green band ratio technique in the near shore are also exacerbated by reflection off the lake bottom in optically shallow water (D'Sa et al, 2002;Lee et al, 2001).…”