Seasonal variation of phytoplankton nutrient limitation in Lake Erie

Abstract

Phosphorus (P) has been identified as the primary nutrient limiting phytoplankton biomass in the Laurentian Great Lakes, and thus phytoplankton biomass varies as a function of P loading. While management efforts have reduced point sources of P, a recent rise in non-point source loadings and the introduction of dreissenid mussels to the Great Lakes are factors suspected to have direct and indirect impacts on nutrient cycling. We re-evaluated nutrient limitation of phytoplankton in the central basin of Lake Erie over spatial (i.e. 3 offshore stations) and temporal (i.e. monthly from June to October) scales. The nutrient limitation of the phytoplankton was evaluated using biomass response measurements to nutrient enrichment bioassays in a complete factorial of P, nitrogen (N), and silicon (Si). Nutrient additions yielded classic growth curves after 7 to 12 d of incubation. Treatments with added P had higher final biomass yields than treatments without P at all stations and during all months. During spring overturn, P+ Si yielded higher phytoplankton biomass than did P additions without Si at 2 of the 3 stations. During the late stratification to autumn overturn (August to October), P+N promoted higher phytoplankton biomass than did P additions without N; this was true at all stations. A quantitative assessment of the bioassays indicated that 63 to 94% of the biomass yield during spring overturn could be attributed to Si, while 48 to 68% of the biomass yield during late stratification and autumn overturn could be attributed to N. Water chemistry data collected in 2002 and 2003 predicted similar seasonal trends in nutrient limitation. These results suggest that seasonal variation in phytoplankton nutrient limitation is a probable factor in predicting changes in phytoplankton biomass and taxonomic composition in the central basin of Lake Erie. KEY WORDS: Phytoplankton · Lake Erie · Nutrient status Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 48: [61][62][63][64][65][66][67][68][69][70][71] 2007 important for effective management initiatives, an area of research where effort has been limited in the past (Elser et al. 1990). Moreover, the Great Lakes Fisheries Commission (GLFC) recognizes that, since the enactment of TP controls and the introduction of non-native dreissenids, many of the changes at the lower trophic levels appear to have influenced both the composition and productivity of the fish communities in the lake, yet little is known about the response at lower trophic levels (GLFC 1998).Nutrient enrichment bioassays have been widely used to evaluate nutrient limitations of phytoplankton (Lin & Schelske 1981). Therefore, we implemented 2 × 3 factorial nutrient enrichment bioassays (NEB) experiments using natural phytoplankton assemblages from Lake Erie to achieve 3 objectives. First, we evaluated the main and interactive effects of P, N, and Si in regulating phytoplankton biomass. Second, we characterized the seasonal and spatial variation of phytop...

Multi-Spectral Remote Sensing of Phytoplankton Pigment Absorption Properties in Cyanobacteria Bloom Waters: A Regional Example in the Western Basin of Lake Erie

“…The MERIS derived seasonal a Gau (435) and a Gau (617.6) variation in Lake Erie follows the pattern recorded in the literature [55,56]. In the central basin of Lake Erie, the different patterns, as shown in Figure 13, are due to the greater nutrients in the spring and autumn, and lower availability in the summer as a result of water stratification.…”

“…In the central basin of Lake Erie, the different patterns, as shown in Figure 13, are due to the greater nutrients in the spring and autumn, and lower availability in the summer as a result of water stratification. The nutrient inputs due to agricultural activities as well as an expanding non-native mussel population, along with the light and temperature changes in different seasons form the main drivers for the different algal bloom patterns in Lake Erie during the four seasons [55][56][57][58][59]. As discovered in Moon [55], the biomass and taxonomic composition and the dominant taxa of surface assemblages varied in different seasons, which can be explained by the light, temperature and nutrient combinations in different seasons, and the strong spatial variability associated with mesoscale physical processes such as upwelling and basin-scale circulation [59].…”

The nitrogen pendulum in Sandusky Bay, Lake Erie: Oscillations between strong and weak export and implications for harmful algal blooms

“…Calls to control eutrophication in Lake Erie have proposed targets for reduced P loading but have largely ignored N (Scavia et al, 2014). However, there is a growing dialogue surrounding the dual management of N and P in lacustrine systems (Gobler at al., 2016;Paerl et al, 2016), particularly as co-limitation of phytoplankton growth by 5 both N and P has been demonstrated in the late summer in Lake Erie (Moon and Carrick, 2007;North et al, 2007;Steffen et al, 2014a). This seasonal N deficiency is consistent with reduced watershed loading of N into the lake's western basin over the past two decades (Stow et al, 2015) combined with active dissimilatory sinks for nitrate (Small et al, 2016).…”

Assessment of Nitrogen deposition effects and empirical critical loads of Nitrogen for ecoregions of the United States

“…Phytoplankton were far more responsive to additions of P, iron (Fe), or Si than N during diff erent seasons (Moon andCarrick 2007, North et al 2007). Studies of Lake Superior have documented a century-long increase in lake NO 3 -concentrations, which has produced a stoichiometric imbalance and strong P limitation ).…”

“…Our analysis of N-limited lakes in lake districts of the United States suggests that, surprisingly, there are relatively large numbers of N-limited lakes in the East (Table 18.2). For those lakes, inputs of N associated with elevated atmospheric deposition are possibly stimulating plant productivity and altering algal communities, although mesotrophic lakes are often limited by P, and large lakes may be limited by Fe (Moon and Carrick 2007, Schindler et al 2008, Wetzel 2001. In a study of hundreds of Swedish lakes along an N deposition gradient, lakes receiving greater than 4 kg N ha -1 yr -1 had greater ratios of chlorophyll a:total P, signifying a eutrophication response (Bergström et al 2005).…”