Recent shifts in water quality and food web characteristics driven by anthropogenic impacts on the Laurentian Great Lakes warranted an examination of pelagic primary producers as tracers of environmental change. The distributions of the 263 common phytoplankton taxa were related to water quality variables to determine taxon-specific responses that may be useful in indicator models. A detailed checklist of taxa and their environmental optima are provided. Multivariate analyses indicated a strong relationship between total phosphorus (TP) and patterns in the diatom assemblages across the Great Lakes. Of the 118 common diatom taxa, 90 (76%) had a directional response along the TP gradient. We further evaluated a diatom-based transfer function for TP based on the weighted-average abundance of taxa, assuming unimodal distributions along the TP gradient. The r2 between observed and inferred TP in the training dataset was 0.79. Substantial spatial and environmental autocorrelation within the training set of samples justified the need for further model validation. A randomization procedure indicated that the actual transfer function consistently performed better than functions based on reshuffled environmental data. Further, TP was minimally confounded by other environmental variables, as indicated by the relatively large amount of unique variance in the diatoms explained by TP. We demonstrated the effectiveness of the transfer function by hindcasting TP concentrations using fossil diatom assemblages in a Lake Superior sediment core. Passive, multivariate analysis of the fossil samples against the training set indicated that phosphorus was a strong determinant of historical diatom assemblages, verifying that the transfer function was suited to reconstruct past TP in Lake Superior. Collectively, these results showed that phytoplankton coefficients for water quality can be robust indicators of Great Lakes pelagic condition. The diatom-based transfer function can be used in lake management when retrospective data are needed for tracking long-term degradation, remediation and trajectories.

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Abstract:The growing complexity and interdependence of water management processes requires the involvement of multiple stakeholders in water governance. Multi-party collaboration is increasingly vital at both the strategy development and implementation levels. Multi-party collaboration involves a process of joint decision-making among key stakeholders in a problem domain directed towards the future of that domain. However, the common goal is not present from the beginning; rather, the common goal emerges during the process of collaboration. Unfortunately, when the conflicting interests of different actors are at stake, the large majority of environmental multi-party efforts often do not reliably deliver sustainable improvements to policy and/or practice. One of the reasons for this, which has been long established by many case studies, is that social learning with a focus on relational practices is missing. The purpose of this paper is to present the design and initial results of a pilot study that utilized a game-based approach to explore the effects of relational practices on the effectiveness of water governance. This paper verifies the methods used by addressing the following question: are game mechanisms, protocols for facilitation and observation, the recording of decisions and results, and participant surveys adequate to reliably test hypotheses about behavioral decisions related to water governance? We used the "Lords of the Valley" (LOV) game, which focuses on the local-level management of a hypothetical river valley involving many stakeholders. We used an observation protocol to collect data on the quality of relational practices and compared this data with the quantitative outcomes achieved by participants in the game. In this pilot study, we ran the game three times with different groups of participants, and here we provide the outcomes within the context of verifying and improving the methods.

We present the first evidence of biological change in all of the pelagic Laurentian Great Lakes associated with recent climatic warming. We hypothesized that measured changes in lake temperature, and the resulting physical changes to water columns, were affecting diatom communities in the Great Lakes. A paleolimnological analysis of 10 sediment cores collected from deep locations throughout the Great Lakes basin indicates a recent (30-50 yr) reorganization of the diatom community to one characterized by elevated abundances of several species from the group Cyclotella sensu lato, coinciding with rising atmospheric and water temperatures. These Cyclotella increases are a probable mechanistic result of new physical regimes such as changing stratification depths and longer ice-free periods, and possibly water quality shifts. Efforts to understand the mechanisms of these changes are ongoing, but this compositional reorganization in primary producers could have important implications to Great Lakes food webs.As atmospheric warming continues, seasonal exposure of lake water columns to sunlight lengthens and ice periods become shorter and less intense. The frequency and duration of stratification events may be expected to increase, as has been observed in Lake Superior (Austin and Colman 2008). Changes to the biota of the Laurentian Great Lakes due to warming are likely occurring. The Great Lakes comprise almost 90% of the surface water resources of North America, so it is imperative to understand the effect of climate shifts on general biology and food webs.Studies of species shifts driven by climate have largely focused on larger flora and fauna (Smol 2012) and usually track how a species alters its phenology or shifts its range. For instance, as a region becomes warmer and wetter, some plants and animals will thrive while other species populations will fragment, shrink and be driven to extinction. Some species adjust to climate change by moving outside their historical geographic boundaries. For phytoplankton, a climate-driven shift tends to mean a change in the dominant flora and reduction or extirpation of previously dominant taxa. It has been recognized in paleorecords from freshwater aquatic systems that phytoplankton, particularly diatoms, exhibit the greatest modification due to recent climate change, followed by invertebrates such as cladocerans and chironomids (R€ uhland et al. 2014). For instance, diatoms in a dated sediment core from Lake of the Woods, northwestern Ontario, were compared to instrumental records (R€ uhland et al. 2008) and Cyclotella sensu lato taxa increased concurrently with a lengthening ice-free period (by almost 30 d in the past 40 yr) and increasing water temperature, providing evidence that warming played a role in diatom community re-organization. Also, a decline in wind speeds over the past 50 yr was significantly correlated with the increasing relative abundance of Cyclotella. Atmospheric warming and associated changes in lake thermal properties were the most plausible ex...

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