Integration of numerical modeling and Bayesian analysis for setting water quality criteria in Hamilton Harbour, Ontario, Canada

Towards the development of an ecosystem model for the Hamilton Harbour, Ontario, Canada

“…The extremely low transfer efficiency from the first to the upper trophic levels and the pyramid-like food web predicted by our ecosystem model are consistent with the idea that nutritional/biochemical factors (e.g., polyunsaturated fatty acids) modulate the trophodynamics in the Harbour (Perhar and Arhonditsis, 2009). Consistent with Gerlofsma et al's (2007) top-down hypothesis, Ramin et al (2011) identified the structural shift towards a zooplankton community dominated by large and fast growing daphnids (and not necessarily the abundance itself) as the most efficient lower food web configuration to achieve compliance with the existing water quality goals. In this regard, the present analysis paints a different picture with regards to the nature of the top-down control exerted on the herbivorous community.…”

“…Increases in macrophyte growth and diversity will create more spawning and nursery habitat for certain native species, which in turn may be another regulatory factor (along with the reduction of the exogenous nutrient loading) to influence the duration of the transient phase and the future resilience of the system. The bottom-up approach historically followed in the Harbour was sufficient to bring the system to its present state, but any further improvements should be viewed in the context of a combined bottom-up and top-down control (Gudimov et al, 2010Ramin et al, 2011).…”

“…By the 1940s, local beaches were closed to swimming and soon thereafter the Harbour water quality deteriorated to its lowest level, resulting in limited public access to the shoreline. The water quality problems were primarily manifested as excessive algal blooms, low water transparency, predominance of toxic cyanobacteria, and low hypolimnetic oxygen concentrations during the late summer (Gudimov et al, 2010Hiriart-Baer et al, 2009;Leslie and Timmins, 1992;Ramin et al, 2011). Further, the elimination of the vegetated littoral zone and the disappearance of essential wetlands and fish nursery habitats, due to infilling for industrial activities as well as for railway or highway construction along the south and east shores of the Harbour, posed major threats to the integrity of the native fish community Holmes and Whillans, 1984;Minns et al, 1994).…”

Nonparametric approaches for estimating regional lake nutrient thresholds

“…Three types of scientifically based approaches recommended by the US Environmental Protection Agency (EPA) have contributed to the development of numerical criteria for Chinese lake ecoregions: the reference condition approach, mechanistic modeling, and stressor-response analysis (US EPA, 2000, 2010. These methods also have been applied in Europe and Canada (Cardoso et al, 2007;Carvalho et al, 2008;Ramin et al, 2011). The reference condition approach, which includes the reference lake, lake population distribution and trisection methods, is preferred for ecoregions with available reference lakes (Dodds and Oakes, 2004;Dodds et al, 2006).…”

“…Many statistical models have been developed to explore the stressor-response relationship between nutrient variables and response variables that are directly or indirectly related to a designated water use (Lamon and Qian, 2008;Ramin et al, 2011;Huo et al, 2014a;Zhang et al, 2014). For example, Lamon and Qian (2008) employed a Bayesian multilevel modeling approach to estimate a linear model for the prediction of chlorophyll a (Chl a) from total nitrogen (TN) and total phosphorus (TP).…”