Timothy Parks - Academia.edu (original) (raw)

Papers by Timothy Parks

Advances in Limnology, 2021

Northeastern Naturalist, 2020

Abstract Coregonus artedi (Cisco) and Coregonus clupeaformis (Lake Whitefish) are coldwater fishe... more Abstract Coregonus artedi (Cisco) and Coregonus clupeaformis (Lake Whitefish) are coldwater fishes native to some inland lakes in Wisconsin. We conducted a statewide assessment of Cisco and Lake Whitefish status using experimental-mesh vertical gillnets during the summers of 2011–2014. Cisco and Lake Whitefish relative abundances varied from 0 to 137 and 0 to 3 fish/net night, respectively. About 29% of the Cisco and 33% of the Lake Whitefish populations were potentially extirpated from inland lakes in Wisconsin; most potential extirpations were from southern Wisconsin, but extirpations occurred statewide. Invasive species, climate change, land-use change, and excess nutrient loading may have contributed to causing extirpations of Cisco and Lake Whitefish. Conservation of remaining populations of Cisco and Lake Whitefish will require efforts to minimize these perturbations.

guidance, and teachings. Their scientific expertise and perspectives really helped to enable my c... more guidance, and teachings. Their scientific expertise and perspectives really helped to enable my creativity and thoughts towards this project. I am very appreciative for their contributions to my education and this project. I would also like to thank Sarah Nusser for her thoughts and statistical insights. I would like to give a special thanks to the my fellow graduate students

Lake and Reservoir Management, 2019

intentionally accommodate change, but minimize undesired outcomes Water Exclosure Treatment Syste... more intentionally accommodate change, but minimize undesired outcomes Water Exclosure Treatment System (WETS) to minimize beach closures Reimer et al., 2018 Climate Change Adaptation Climate Change Adaptation Actions Response minimize undesired outcomes communication and outreach policy and regulation traditional conservation innovation and engineering Lake Ecosystem Human Dimension Adaptation Approaches Resistance defend and protect against changes Resilience reduce stress and minimize vulnerability Adaptation Actions Communication Communicate climate change impacts to stakeholders and manage expectations for resource use in the future Policy Rules and Regulations that adapt to climate changes by requiring adaptations that promote resistance and resilience on a structural level Conservation Traditional conservation practices on the landscape that build resilience within the system Engineering

Fisheries, 2019

Successful fisheries management practices developed for one ecosystem can often be used in simila... more Successful fisheries management practices developed for one ecosystem can often be used in similar ecosystems. We developed a flexible lake classification framework in collaboration with ~100 fisheries biologists for improved fisheries conservation management in Wisconsin, USA. In total, 5,950 lakes were classified into 15 lake classes using a two-tiered approach. In tier-one, lakes were clustered into "simple" and "complex" sportfish assemblages. In tier-two, lakes were further clustered using accumulated degree days, water clarity, and special cases. We focus on temperature and clarity because these factors often drive fisheries change over time-thus a lake's class can change over time. Lake class assignments were refined through a vetting process where fisheries biologists with expert knowledge provided feedback. Relative abundance, size-structure, and growth rates of fishes varied significantly across classes. Biologists are encouraged to utilize class interquartile ranges in fisheries metrics to make improved fisheries assessments. We highlight hard-won lessons from our effort including: (1) the importance of co-developing classification frameworks alongside fisheries biologists; and (2) encouraging frameworks where lakes can shift classes and fisheries expectations over time due to factors like climate change and eutrophication.

River Research and Applications, 2014

Nonwadeable rivers are unique ecosystems that support high levels of aquatic biodiversity, yet th... more Nonwadeable rivers are unique ecosystems that support high levels of aquatic biodiversity, yet they have been greatly altered by human activities. Although riverine fish assemblages have been studied in the past, we still have an incomplete understanding of how fish assemblages respond to both natural and anthropogenic influences in large rivers. The purpose of this study was to evaluate associations between fish assemblage structure and reach-scale habitat, dam, and watershed land use characteristics. In the summers of 2011 and 2012, comprehensive fish and environmental data were collected from 33 reaches in the Iowa and Cedar rivers of eastern-central Iowa. Canonical correspondence analysis (CCA) was used to evaluate environmental relationships with species relative abundance, functional trait abundance (e.g. catch rate of tolerant species), and functional trait composition (e.g. percentage of tolerant species). On the basis of partial CCAs, reach-scale habitat, dam characteristics, and watershed land use features explained 25.0-81.1%, 6.2-25.1%, and 5.8-47.2% of fish assemblage variation, respectively. Although reach-scale, dam, and land use factors contributed to overall assemblage structure, the majority of fish assemblage variation was constrained by reach-scale habitat factors. Specifically, mean annual discharge was consistently selected in nine of the 11 CCA models and accounted for the majority of explained fish assemblage variance by reach-scale habitat. This study provides important insight on the influence of anthropogenic disturbances across multiple spatial scales on fish assemblages in large river systems.

Canadian Journal of Fisheries and Aquatic Sciences, 2017

The cisco (Coregonus artedi) requires cold, well-oxygenated water and is threatened by climate wa... more The cisco (Coregonus artedi) requires cold, well-oxygenated water and is threatened by climate warming and lake eutrophication, especially at the southern edge of its range in the Laurentian Great Lakes region. In this paper, a method is described to assess the quality, quantity, and variability of suitable cisco habitat. Two metrics are proposed to characterize existing cisco oxythermal habitat in this region: water temperature in the water column at a dissolved oxygen of 6 mg/L (TDO6) and “cisco layer thickness” (CLT), the vertical extent of the water column within which water temperature is ≤22.8 °C and dissolved oxygen is ≥6 mg/L. It is proposed that values of TDO6 = 22.8 °C and CLT = 1 m be used as benchmarks to identify cisco lakes with potentially stressful oxythermal habitat. Long-term summer data from 14 Wisconsin cisco lakes with a wide range of limnological characteristics indicated that TDO6 varied from 4.2 to 27.5 °C and CLT from −6.2 to 66.7 m. Cisco abundance across l...

The American Midland Naturalist, 2014

Historical change in fish assemblage structure was evaluated in the mainstems of the Des Moines, ... more Historical change in fish assemblage structure was evaluated in the mainstems of the Des Moines, Iowa, Cedar, Wapsipinicon, and Maquoketa rivers, in Iowa. Fish occurrence data were compared in each river between historical and recent time periods to characterize temporal changes among 126 species distributions and assess spatiotemporal patterns in faunal similarity. A resampling procedure was used to estimate species occurrences in rivers during each assessment period and changes in species occurrence were summarized. Spatiotemporal shifts in species composition were analyzed at the river and river section scale using cluster analysis, pairwise Jaccard's dissimilarities, and analysis of multivariate beta dispersion. The majority of species exhibited either increases or declines in distribution in all rivers with the exception of several ''unknown'' or inconclusive trends exhibited by species in the Maquoketa River. Cluster analysis identified temporal patterns of similarity among fish assemblages in the Des Moines, Cedar, and Iowa rivers within the historical and recent assessment period indicating a significant change in species composition. Prominent declines of backwater species with phytophilic spawning strategies contributed to assemblage changes occurring across river systems.

Canadian Journal of Fisheries and Aquatic Sciences, 2018

We quantified production, biomass, and production to biomass (P/B) ratios for cisco (Coregonus ar... more We quantified production, biomass, and production to biomass (P/B) ratios for cisco (Coregonus artedi) in Trout Lake, Wisconsin, USA (2001–2015). Across all years, annual production, biomass, and P/B were variable ranging 0.6–30.2 kg·ha−1·year−1, 1.2–39.7 kg·ha−1, and 0.4–0.9·year−1, respectively. Cisco production exhibited obvious decline. However, neither biomass nor P/B changed significantly over time. Long-term patterns of environmental conditions remained unchanged during the study and were unrelated to cisco production. However, lake trout (Salvelinus namaycush) relative abundance showed a strong inverse relationship with cisco production and biomass. Intense lake trout stocking has occurred in this lake over time to conserve a genetically unique strain of the species. These management efforts may have had the unintended consequence of amplifying top-down predation on cisco. Since cisco P/B has gone largely unchanged, cisco production would be predicted to rebound quickly to a...