Christopher T. Solomon’s research while affiliated with Cary Institute of Ecosystem Studies and other places

Understanding controls on primary productivity is essential for describing ecosystems and their responses to environmental change. In lakes, pelagic gross primary productivity (GPP) is strongly controlled by inputs of nutrients and dissolved organic matter. Although past studies have developed process models of this nutrient‐color paradigm (NCP), broad empirical tests of these models are scarce. We used data from 58 globally distributed, mostly temperate lakes to test such a model and improve understanding and prediction of the controls on lake primary production. The model includes three state variables–dissolved phosphorus, terrestrial dissolved organic carbon (DOC), and phytoplankton biomass–and generates realistic predictions for equilibrium rates of pelagic GPP. We calibrated our model using a Bayesian data assimilation technique on a subset of lakes where DOC and total phosphorus (TP) loads were known. We then asked how well the calibrated model performed with a larger set of lakes. Revised parameter estimates from the updated model aligned well with existing literature values. Observed GPP varied nonlinearly with both inflow DOC and TP concentrations in a manner consistent with increasing light limitation as DOC inputs increased and decreasing nutrient limitation as TP inputs increased. Furthermore, across these diverse lake ecosystems, model predictions of GPP were highly correlated with observed values derived from high‐frequency sensor data. The GPP predictions using the updated parameters improved upon previous estimates, expanding the utility of a process model with simplified assumptions for water column mixing. Our analysis provides a model structure that may be broadly useful for understanding current and future patterns in lake primary production.

Catch‐and‐release (C&R) angling is often used to maintain high catch rates but fish vulnerability to capture may decrease following hooking, thereby decreasing angler catch per unit effort (CPUE) (hyperdepletion). To determine if fish post‐capture response affected recapture probability and population‐level CPUE, individual capture histories of Largemouth Bass in two lakes were compared before and after doubling angling effort in a Before‐After Control‐Impact (BACI) analysis. Previous capture and day‐of‐season both affected recapture probability. Counteracting effects of previous capture and reduced late‐season catch rates caused no hyperdepletion of angler CPUE. Our results highlight the complexity of fish behavioral responses to angling and suggest that hyperdepletion of angling catch rates may not be an issue in C&R fisheries.

Adapting to social and environmental change requires learning and governance that span ecological levels, political jurisdictions, and management challenges. Governance of these challenges is often comprised of public and private sector actors with overlapping jurisdictions that work together—termed polycentric governance. Polycentric governance systems have been found to improve adaptability through learning. In this paper, we compare how local organizations perceive a governance systems’ function and structure to help them learn and adapt to change. In our interviews with organization leaders in three north-central US states, we used expert elicitation to compare the degree to which the organizations’ partners help them experiment and learn to adapt to challenges. The challenges most frequently identified included social challenges like sharing knowledge and funding as well as ecological issues related to the resource. The associated polycentric governance systems’ structures varied by state. Independence and jurisdictional overlap—measures of polycentricity—differed by partner type, while consideration of partners’ best practices was similar for all partner types. Most partners were said to provide helpful information and respond to queries facilitating learning, but government partners were not always encouraging innovation or flexible implying less space for experimentation. We found that in each of the three states there is a mixture of actors at multiple scales partnering with the lake organizations at different frequencies and modes of interaction. We conclude that polycentric governance is beneficial for learning and experimentation, and that different structures may be beneficial to adapting within different contexts or problems definitions. The challenge for these systems is controlling areas of risk while providing flexibility to experiment and adapt to changing conditions.

Widespread and increasing use of road deicing salt is a major driver of increasing lake chloride concentrations, which can negatively impact aquatic organisms and ecosystems. We used a simple model to explore the controls on road salt concentrations and predict equilibrium concentrations in lakes across the contiguous United States. The model suggests that equilibrium salt concentration depends on three quantities: salt application rate, road density, and runoff (precipitation minus evapotranspiration). High application combined with high road density leads to high equilibrium salt concentrations regardless of runoff. Yet if application can be held at current rates or reduced, concentrations in many lakes situated in lightly to moderately urbanized watersheds should equilibrate at levels below currently recommended thresholds. In particular, our model predicts that, given 2010–2015 road salt application rates, equilibrium chloride concentrations in the contiguous United States will exceed the current regulatory chronic exposure threshold of 230 mg L ⁻¹ in over 2000 lakes; will exceed 120 mg L ⁻¹ in over 9000 lakes; and will be below 120 mg L ⁻¹ in hundreds of thousands of lakes. Our analysis helps to contextualize current trends in road salt pollution of lakes, and suggests that stabilization of equilibrium chloride concentrations below thresholds designed to protect aquatic organisms should be an achievable goal.

Synthesis research in ecology and environmental science improves understanding, advances theory, identifies research priorities, and supports management strategies by linking data, ideas, and tools. Accelerating environmental challenges increases the need to focus synthesis science on the most pressing questions. To leverage input from the broader research community, we convened a virtual workshop with participants from many countries and disciplines to examine how and where synthesis can address key questions and themes in ecology and environmental science in the coming decade. Seven priority research topics emerged: (1) diversity, equity, inclusion, and justice (DEIJ), (2) human and natural systems, (3) actionable and use-inspired science, (4) scale, (5) generality , (6) complexity and resilience, and (7) predictability. Additionally, two issues regarding the general practice of synthesis emerged: the need for increased participant diversity and inclusive research practices; and increased and improved data flow, access, and skill-building. These topics and practices provide a strategic vision for future synthesis in ecology and environmental science.

In commercial and recreational fisheries, catch rate is often assumed to be proportional to stock size and is used by managers and fishers as an indicator of fishery sustainability. If catch rate is proportional to stock size, it can signal a decline of stocks and managers can impose restrictive harvest policies or recreational anglers can move to a new system and allow the over-exploited system to rebound. A growing literature has documented catch rates remaining high even as fish stocks decline (i.e., hyperstability of catch rates) leading to delayed management intervention and overexploitation. Although recent evidence has indicated the presence of hyperstability of catch rates in recreational fisheries, whether hyperstability differs across species or system types remains unknown. To investigate whether catch rate hyperstability varies amongst species or systems, we first tested whether electrofishing catch per unit effort (efCPUE) was an appropriate proxy for true abundance. We then compared the relationship between angler catch rate and fish abundance for common freshwater sport fishes across gradients of habitat availability. We found significant differences in the strength of hyperstability amongst species. We did not identify a consistent influence of habitat on hyperstability of catch rates. Angler preferences and behavior may explain some of the variance in non-proportional catch rates. Future research investigating angler behavior, population size structure, and population dynamics in these systems may identify key interactions that create differences in vulnerability to population collapse.

Simple theoretical models predicting recreational fisheries’ ability to self-regulate often fail in practice. These models may be misinformed because they do not account for anglers’ limited knowledge of fish abundance across a suite of potential fishing opportunities. We present results from a novel creel survey specifically designed to elicit angler information source use to understand the relationships between knowledge sources, catch expectations, and actual catch. We surveyed 38 lakes within the Northern Highland Lake District (NHLD) of Wisconsin, USA. Anglers (n = 509) were interviewed before and after their fishing trip to collect data on target species, expected catch, actual catch, information source usage, trip-level satisfaction, and angler demographics. Most respondents (~71%) primarily relied on their own personal experience when making fishing decisions. Information source did not influence the accuracy of anglers' expectations about catch rates. Mean expected catches were higher than mean actual catches for bass, walleye, and muskellunge, but not significantly different for panfish. Simple linear models revealed that the type and number of information sources used did not significantly contribute to anglers’ catch prediction accuracy. Ordinal logistic regression modelling of anglers’ overall trip satisfaction revealed that the difference between expected and actual catch is a significant variable in determining anglers’ trip satisfaction. Our results suggest that recreational fisheries information does not flow readily within the NHLD, and calls into question common model assumptions made about angler knowledge of alternative fishing opportunities and how to model angler experience and ability.