FUNCTIONAL CONSEQUENCES OF SPECIES RANGE SHIFTS IN SUBALPINE WETLANDS
I have been working in a pond and wetland system near the Rocky Mountain Biological Laboratory since I was an undergraduate at Allegheny College. This system is exciting because it features multiple ecological gradients that structure pond community compositions. These include an elevational gradient from the montane (~8000m) to the subalpine (~12800m), and a “predator-permanence” gradient that determines what kinds of predators are present (vertebrate vs invertebrate) and how long the ponds are inundated (temporary ponds which dry annually, semi-permanent which dry in some but not all years, and permanent which never dry). Moreover, our long-term monitoring of this system has documented 7 upslope species range expansions over the past 30 years. Thus, climate change is altering pond community compositions. My contributions to this body of research primarily explore the contributions of individual species and of the whole pond community to multiple critical ecosystem functions (nutrient cycling and detritus processing) both along ecological gradients and over the course of the long-term dataset. Here is a link to recording of an invited seminar about this work, hosted by the Rocky Mountain Biological Laboratory on 21 June 2022. Otherwise, read more about some of my individual publications below!
High interspecific variation in nutrient excretion within a guild of closely related caddisfly speciesBalik, J. A., Taylor, B. W., Washko, S. E., & Wissinger, S. A. (2018). High interspecific variation in nutrient excretion within a guild of closely related caddisfly species. Ecosphere, 9(5), e02205. (DOI, PDF) Organisms can have large effects on ecosystem processes such as nutrient cycling, but these can be difficult to study directly in natural systems. Single species contributions are often particularly challenging to isolate and measure. However, species’ functional traits provide mechanistic links between organisms and their effects on ecosystem processes, and thus provide an indirect method of understanding species’ functional roles and contributions to overall ecosystem processes. In this first chapter of my dissertation, I quantified species-specific nutrient excretion rates of larval caddisflies that are biomass-dominant detritivores in subalpine ponds. I found considerable interspecific variation in biomass-specific excretion of nitrogen (eightfold differences) and phosphorus (sevenfold differences) among 10 larval caddisfly species. Then, through a meta-analysis, I compared the variation within this guild to the overall range in variation found among other family-level assemblages and found that, comparatively, the interspecific variation among caddisfly excretion rates was high for N and intermediate for P. This suggests that functional redundancy among species is difficult to predict, and consequently the functional outcomes of species gains or losses could be substantial. |
Animal-driven nutrient supply declines relative to ecosystem nutrient demand along a pond hydroperiod gradientBalik, J. A., Jameson, E. E., Wissinger, S. A., Whiteman, H. H., & Taylor, B. W. (2021). Animal-Driven Nutrient Supply Declines Relative to Ecosystem Nutrient Demand Along a Pond Hydroperiod Gradient. Ecosystems, 1-19. (DOI, PDF) Here, I combine nutrient excretion rates and biomasses of pelagic and benthic invertebrates and salamanders with nutrient uptake rates in a novel simulation model to estimate animal-driven nutrient supply and pond-level demand along a hydroperiod gradient of permanent ponds that never dry, semi-permanent ponds that dry in some years, and temporary ponds that dry annually. I found that animal biomass increased with hydroperiod duration, and biomass predicted animal-driven supply contributions among hydroperiod classifications. Consequently, community-wide supply was greatest in permanent ponds. N supply exceeded demand in permanent and semi-permanent ponds, whereas P supply equaled demand in both. Conversely, temporary ponds had large deficits in both nutrients due to lower biomass and hydroperiod-induced constraints on dominant suppliers (oligochaetes and chironomids). Thus, as climate warming causes hydroperiods to become increasingly temporary and indirectly prompts biomass declines and compositional shifts, animal-driven nutrient supply will decrease and strong nutrient limitation may arise due to loss of animal-driven supply. |
Ongoing work in this System
NSF Postdoctoral Research - Curating and archiving long-term ecological datasets
Through my first NSF Postdoctoral Scholar position at NCSU, I curated a 30-year dataset of montane and subalpine pond aquatic invertebrate community composition and pond hydrology. This dataset was the life's work of my late undergraduate advisor, Dr. Scott Wissinger. Unfortunately, when Scott unexpectedly passed away in October 2019, the overwhelming majority of his long-term survey data was still handwritten in field books. Scott and I had continued collaborating during my doctoral studies, and I needed some of his long-term survey data to complete my final dissertation chapter. So, in winter 2020 I digitized the larval caddisfly component of his pond surveys. However, additional surveys for the broader benthic invertebrate community and notes on pond hydrology (ice melt, drying, refilling, and freeze phenology) remained. Thus, to ensure that this incredible dataset is preserved for future scientists, my doctoral advisor Brad Taylor and I sought out additional funding for me to remain in his lab after my graduation to finish curating Scott's long-term datasets. As of summer 2022, our collaborative research group (see below) is finalizing plans for archiving the datasets. Various manuscripts utilizing this long term dataset are forthcoming!
Through my first NSF Postdoctoral Scholar position at NCSU, I curated a 30-year dataset of montane and subalpine pond aquatic invertebrate community composition and pond hydrology. This dataset was the life's work of my late undergraduate advisor, Dr. Scott Wissinger. Unfortunately, when Scott unexpectedly passed away in October 2019, the overwhelming majority of his long-term survey data was still handwritten in field books. Scott and I had continued collaborating during my doctoral studies, and I needed some of his long-term survey data to complete my final dissertation chapter. So, in winter 2020 I digitized the larval caddisfly component of his pond surveys. However, additional surveys for the broader benthic invertebrate community and notes on pond hydrology (ice melt, drying, refilling, and freeze phenology) remained. Thus, to ensure that this incredible dataset is preserved for future scientists, my doctoral advisor Brad Taylor and I sought out additional funding for me to remain in his lab after my graduation to finish curating Scott's long-term datasets. As of summer 2022, our collaborative research group (see below) is finalizing plans for archiving the datasets. Various manuscripts utilizing this long term dataset are forthcoming!
NSF Postdoctoral Research - Do range shifting species alter ecosystem phenology?
In September 2021 I became a co-PI on an NSF-RAPID grant [with colleagues Drs. Amanda Klemmer (lead PI) and Hamish Greig (both University of Maine) and Howard Whiteman (Murray State University)] to study how a range shifting larval caddisfly species alters the phenology of ecosystem processes. Briefly, during our 2021 summer field season at the Rocky Mountain Biological Laboratory, we documented an unprecedented population explosion of a recent range shifting caddisfly, Nemotaulius hostilis. Based on egg mass counts, we predict a 10-84 fold increase in the density of N. hostilis over that previously observed in these ponds. This increase in a potentially highly-interactive detritivore is unparalleled in our (Scott Wissinger's) previous 30 years of data collection on any caddisfly or other invertebrate species. Our extensive sampling of the caddisflies, their salamander predators (diet and condition), and associated ecosystem processes (nutrient excretion and detritus breakdown) as the eggs began hatching in August 2021 and as the larvae develop into spring 2022 will allow us to understand the mechanisms and implications of this unexpected and dramatic biotic perturbation. Various manuscripts about this range expanding species are forthcoming! |