Pringle Catherine M.

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Pringle
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Catherine M.
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  • Article
    Testing isosource : stable isotope analysis of a tropical fishery with diverse organic matter sources
    (Ecological Society of America, 2006-02) Benstead, Jonathan P. ; March, James G. ; Fry, Brian ; Ewel, Katherine C. ; Pringle, Catherine M.
    We sampled consumers and organic matter sources (mangrove litter, freshwater swamp-forest litter, seagrasses, seagrass epiphytes, and marine particulate organic matter [MPOM]) from four estuaries on Kosrae, Federated States of Micronesia for stable isotope (δ13C and δ34S) analysis. Unique mixing solutions cannot be calculated in a dual-isotope, five-endmember scenario, so we tested IsoSource, a recently developed statistical procedure that calculates ranges in source contributions (i.e., minimum and maximum possible). Relatively high minimum contributions indicate significant sources, while low maxima indicate otherwise. Litter from the two forest types was isotopically distinguishable but had low average minimum contributions (0–8% for mangrove litter and 0% for swamp-forest litter among estuaries). Minimum contribution of MPOM was also low, averaging 0–13% among estuaries. Instead, local marine sources dominated contributions to consumers. Minimum contributions of seagrasses averaged 8–47% among estuaries (range 0–88% among species). Minimum contributions of seagrass epiphytes averaged 5–27% among estuaries (range 0–69% among species). IsoSource enabled inclusion of five organic matter sources in our dual-isotope analysis, ranking trophic importance as follows: seagrasses > seagrass epiphytes > MPOM > mangrove forest > freshwater swamp-forest. IsoSource is thus a useful step toward understanding which of multiple organic matter sources support food webs; more detailed work is necessary to identify unique solutions.
  • Preprint
    Leaf litter nutrient uptake in an intermittent blackwater river : influence of tree species and associated biotic and abiotic drivers
    ( 2014-12) Mehring, Andrew S. ; Kuehn, Kevin A. ; Thompson, Aaron ; Pringle, Catherine M. ; Rosemond, Amy D. ; First, Matthew R. ; Lowrance, R. Richard ; Vellidis, George
    Organic matter may sequester nutrients as it decomposes, increasing in total N and P mass via multiple uptake pathways. During leaf litter decomposition, microbial biomass and accumulated inorganic materials immobilize and retain nutrients, and therefore both biotic and abiotic drivers may influence detrital nutrient content. We examined the relative importance of these types of nutrient immobilization and compared patterns of nutrient retention in recalcitrant and labile leaf litter. Leaf packs of water oak (Quercus nigra), red maple (Acer rubrum) and Ogeechee tupelo (Nyssa ogeche) were incubated for 431 days in an intermittent blackwater stream and periodically analyzed for mass loss, nutrient and metal content, and microbial biomass. These data informed regression models explaining temporal changes in detrital nutrient content. Informal exploratory models compared estimated biologically-associated nutrient stocks (fungal, bacterial, leaf tissue) to observed total detrital nutrient stocks. We predicted that (1) labile and recalcitrant leaf litter would act as sinks at different points in the breakdown process, (2) plant and microbial biomass would not account for the entire mass of retained nutrients, and (3) total N content would be more closely approximated than total P content solely from nutrients stored in leaf tissue and microbial biomass, due to stronger binding of P to inorganic matter. Labile litter had higher nutrient concentrations throughout the study. However, lower mass loss of recalcitrant litter facilitated greater nutrient retention over longer incubations, suggesting that it may be an important long-term sink. N and P content were significantly related to both microbial biomass and metal content, with slightly stronger correlation to metal content over longer incubations.