Trophic cascade within and across ecosystems: the role of anti-predatory defenses, predator type, and detritus quality

Species in one ecosystem can indirectly affect multiple biodiversity components and ecosystem functions of adjacent ecosystems. The magnitude of these cross-ecosystem effects depends on the attributes of the organisms involved in the interactions, including traits of the predator, prey and basal resource. However, it is unclear how predators with cross-ecosystem habitat interact with predators with single-ecosystem habitat to affect their shared ecosystem. Also, unknown is how such complex top-down effects may be mediated by the anti-predatory traits of prey and quality of the basal resource.
We used the aquatic invertebrate food webs in tank bromeliads as a model system to investigate these questions. We manipulated the presence of a strictly aquatic predator (damselfly larvae) and a predator with both terrestrial and aquatic habitats (spider) and examined effects on survival of prey (detritivores grouped by anti-predator defense), detrital decomposition (of two plant species differin..., Between January and March 2010 (35 days), we manipulated predators and detritivores within bromeliads settled within experimental cages. Each cage consisted of a rectangular wire frame (0.50m × 0.60m) covered with a white fabric mesh that allowed moderate light to pass through, fixed to the top edge of a pot into which the experimental bromeliad was planted. An emergence trap, made of an inverted plastic bottle, was placed on top of each cage to capture adults of detritivores that emerged during the experiment.
We randomly arranged these 48 bromeliads into 12 blocks of four bromeliads, with a minimum distance of 20 meters between blocks. We randomly assigned each block to the following treatments: (i) only detritivores, without predators (control treatment); (ii) detritivores + damselfly larva; (iii) detritivores + spider; (iv) detritivores + damselfly larva + spider. We used an additive design, in which the density of each predator species is held constant since this design, unlike a s..., , # Trophic cascade within and across ecosystems: the role of anti-predatory defenses, predator type, and detritus quality

The dataset is from a field experiment, in which we investigate how predators from adjacent ecosystems (aquatic and ecross ecosystem predators) affect functional groups of aquatic detritivores which differ in anti-predator defense, and indirectly detritus decomposition, nutrient cycling, and host plant growth. We used the aquatic invertebrate food webs in tank bromeliads as a model system to investigate these questions. We manipulated the presence of a strictly aquatic predator (damselfly larvae) and a predator with both terrestrial and aquatic habitats (spider), and examined effects on survival of prey (detritivores grouped by anti-predator defense), detrital decomposition (of two plant species differing in litter quality), nitrogen flux (15N) and host plant growth.

Damselfly larvae and spiders each directly decreased survival of detritivores and caused multiple ...