@article {KNZ001776, title = {Long-term changes in structure and function of a tropical headwater stream following a disease-driven amphibian decline}, journal = {Freshwater Biology}, volume = {60}, year = {2015}, pages = {575 - 589}, abstract = {

1. Taxonomic and functional diversity in freshwater habitats is rapidly declining, but we know little about how such declines will ultimately affect ecosystems. Neotropical streams are currently experiencing massive losses of amphibians, with many losses linked to the chytrid fungus, Batrachochytrium dendrobatidis (Bd). 2. We examined the ecological consequences of the disease-driven loss of amphibians from a Panamanian stream. We quantified basal resources, macroinvertebrates, N uptake and fluxes through food-web components and ecosystem metabolism in 2012 and 2014 and compared them to pre-decline (2006) and 2 year post-decline (2008) values from a prior study. 3. Epilithon biomass accrued after the decline, more than doubling between 2006 and 2012, but then decreased fivefold from 2012 to 2014. In contrast, suspended particulate organic matter (SPOM) concentrations declined continuously after the amphibian decline through 2014. 4. Biomass of filter-feeding, grazing and shredding macroinvertebrates decreased from 2006 to 2014, while collector\–gatherers increased during the same time period. Macroinvertebrate taxa richness decreased from 2006 (52 taxa) to 2012 (30 taxa), with a subsequent increase to 51 taxa in 2014. 5. Community respiration, which initially decreased after the amphibian decline, remained lower than pre-decline in 2012 but was greater than pre-decline values in 2014. Gross primary production remained low and similar among years, while inline image uptake length in both 2012 and 2014 was longer than pre-decline. Nitrogen flux to epilithon increased after the decline and continued to do so through 2014, but N fluxes to fine particulate organic matter and SPOM decreased and remained low. 6. Our findings underscore the importance of studying the ecological consequences of declining biodiversity in natural systems over relatively long time periods. There was no evidence of functional redundancy or compensation by other taxa after the loss of amphibians, even after 8 years.

}, keywords = {LTER-KNZ}, doi = {10.1111/fwb.12505}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/fwb.12505}, author = {Rantala, H.M. and Nelson, A.M. and Fulgoni, J.N. and M.R. Whiles and Hall, R.O. and W. K. Dodds and Verburg, P. and Huryn, A. and Pringle, C.. and Kilham, S.S. and Lips, K.R. and Colon-Gaud, C. and Rugenski, A.T. and Peterson, S.D. and Fritz, K. and McLeran, K.E. and Connelly, S.} } @article {KNZ001767, title = {Patch-burn grazing effects on the ecological integrity of tallgrass prairie streams}, journal = {Journal of Environment Quality}, volume = {44}, year = {2015}, pages = {1148}, abstract = {

Conversion to agriculture, habitat fragmentation, and the loss of native grazers have made tallgrass prairie one of the most endangered ecosystems. One management option for the remaining prairie parcels, patch-burn grazing (PBG), applies a controlled burn to a portion of the prairie to attract cattle, creating a mosaic of more- and less-grazed patches. Although beneficial to cattle and grassland birds, the potential impacts of PBG on streams have not been studied, and a holistic approach is needed to ensure against adverse effects. We used a Before-After-Control-Impact design to assess potential impacts of PBG with and without riparian protection on tallgrass prairie headwater streams. We sampled stream macroinvertebrates and benthic organic matter 2 yr before and 2 yr during PBG treatments on two grazed watersheds with riparian fencing (fenced), two unfenced grazed watersheds (unfenced), and two ungrazed (control) watersheds. Very fine benthic organic matter increased significantly (51\%) in unfenced streams compared with controls ( \< 0.007), and fine particulate organic matter (\<1 mm and \>250 \µm) increased 3-fold in the unfenced streams compared with controls ( = 0.008). The contribution of fine inorganic sediments to total substrata increased 28\% in unfenced streams during PBG, which was significantly different from controls ( = 0.03). Additionally, the abundance of Ephemeroptera, Plecoptera, and Trichoptera taxa decreased from 7635 to 687 individuals m in unfenced streams, which was significantly lower than in control streams ( = 0.008). Our results indicate that PBG adversely influences prairie streams through sediment inputs and reductions in sensitive invertebrate taxa, but riparian fencing can alleviate these impacts.

}, keywords = {LTER-KNZ}, doi = {10.2134/jeq2014.10.0437}, url = {https://dl.sciencesocieties.org/publications/jeq/abstracts/44/4/1148}, author = {Jackson, K.E. and M.R. Whiles and W. K. Dodds and Reeve, J.D. and Vandermyde, J.M. and Rantala, H.M.} } @article {KNZ001626, title = {You are not always what we think you eat: selective assimilation across multiple whole-stream isotopic tracer studies}, journal = {Ecology}, volume = {95}, year = {2014}, pages = {2757 -2767}, abstract = {

Analyses of 21 15N stable isotope tracer experiments, designed to examine food web dynamics in streams around the world, indicated that the isotopic composition of food resources assimilated by primary consumers (mostly invertebrates) poorly reflected the presumed food sources. Modeling indicated that consumers assimilated only 33\–50\% of the N available in sampled food sources such as decomposing leaves, epilithon, and fine particulate detritus over feeding periods of weeks or more. Thus, common methods of sampling food sources consumed by animals in streams do not sufficiently reflect the pool of N they assimilate. Isotope tracer studies, combined with modeling and food separation techniques, can improve estimation of N pools in food sources that are assimilated by consumers. Food web studies that use putative food samples composed of actively cycling (more readily assimilable) and refractory (less assimilable) N fractions may draw erroneous conclusions about diets, N turnover, and trophic linkages of consumers. By extension, food web studies using stoichiometric or natural abundance approaches that rely on an accurate description of food-source composition could result in errors when an actively cycling pool that is only a fraction of the N pool in sampled food resources is not accounted for.

}, keywords = {LTER-KNZ}, doi = {10.1890/13-2276.1}, url = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/13-2276.1}, author = {W. K. Dodds and Scott. L. Collins and Hamilton, S.K. and Tank, J.L. and Johnson, S. and Webster, J.R. and Simon, K.S. and M.R. Whiles and Rantala, H.M. and W.H. McDowell and Peterson, S.D. and Riis, T. and Crenshaw, C.L. and Thomas, S.A. and Kristensen, P.B. and Cheever, B.M. and Flecker, A.S. and Griffiths, N.A. and Crowl, T. and Rosi-Marshall, E.J. and El-Sabaawi, R. and Marti, E.} }