Effects of prey nutrient content on spider excreta content and soil-carbon mineralization rates
Abstract
Recent work suggests that predators can play a fundamental role in cycling nutrients throughout ecosystems. Through consumer-driven effects, including depositing excreta
and uneaten parts of prey carcasses, predators can influence ecosystem function by
altering the amount and type of nutrients available to soil communities and primary
producers. In this study, I examined how different prey fed to a spider affected the forms
and concentrations of nutrients deposited, and their subsequent effects on ecosystem
function (soil-carbon mineralization rates). More specifically I examined: 1) The
differences in elemental concentrations of prey remains and spider excreta when spiders
fed on different species of prey (caterpillars, cockroaches, crickets, and flies). 2) If the
concentrations of elements deposited by spiders differ between spring and fall. 3) The
effects of spider excreta from different predator-prey interactions on soil-carbon
mineralization rates. Overall, spider excreta generally had higher concentrations of many
elements compared to prey remains, and whole prey. Additionally, elemental
concentrations in whole prey and remains exhibited significant variation among prey
species, while spider excreta had the lowest variation. Seasonally, there were significant
differences in the concentrations of elements deposited between fall and spring excreta.
Finally, soil-carbon mineralization rates were higher in controls than in soil with excreta
from spiders fed caterpillars, cockroaches, and flies, with crickets being intermediate.
The results from this study highlight the complex interactions between predator and prey
physiology that determine the concentrations of elements deposited following predation.
A better understanding of how other predatory-prey interactions impact nutrient
feedbacks will be critical to disentangle specific consumer-driven effects on ecosystem
function.
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- OSU Theses [15752]