Subsidiary intermediaries: The role of aqutic plants in storing and transfering resources from aquatic biochemical hotspots to therrestrial ecosystems
Lopez, J . 2022.
Abstract
The roles mobile animals and abiotic processes play as vectors for resource transfers between ecosystems ("subsidies") are well-studied, but the idea that resources from animals with limited mobility may be transported across boundaries through intermediate taxa remains unexplored. Aquatic plants ("macrophytes") are globally distributed and may mediate transfers
of aquatic-derived nutrients from aggregations of aquatic animals to terrestrial ecosystems when consumed by terrestrial herbivores. We used mesocosms (94×44 cm) to test whether aquatic animal-generated biogeochemical hotspots increase growth and nutrient content in macrophytes using the macrophyte Justicia americana and freshwater mussels. J. americana biomass production increased and belowground biomass allocation changed with increasing mussel
density. At high mussel density, water column phosphorus increased and carbon:phosphorus ratios in J. americana tissues decreased. We deployed motion-sensing cameras to explore herbivory on J. americana growing along the margins of the Kiamichi River, Oklahoma, and documented feeding by large mammals (Odocoileus virginianus, Sus scrofa, and Bos taurus). Thus, biogeochemical hotspots generated by aquatic animal aggregations can promote
macrophyte production that subsequently is transferred to terrestrial animals. More broadly, this suggests that reductions in aquatic animal biomass may have bottom-up impacts that indirectly
affect terrestrial ecosystems via plant-animal interactions bridging ecosystem boundaries.
