Data and code from: Goby gummies: a customizable and edible assay to quantify predation in aquatic ecosystems

Predation is a critical ecosystem process that shapes the structure and
functioning of biological communities. However, due to its intermittent
nature, fast pace, and general unpredictability, predation is difficult to
observe and quantify. Therefore, we commonly rely on indirect metrics or
proxies of predation, which reflect the outcome of predation events but do
not allow for inference about the predator’s decision-making process or
predation rates. In terrestrial ecosystems, lifelike prey replicas have
allowed ecologists to gain a broad understanding of predator choice,
predation intensity, and their drivers. Yet in aquatic ecosystems, few
scalable, interactive predation assays have been developed. We introduce
Goby Gummies, a customizable, edible prey model developed for aquatic
ecology. Gummies are constructed using an inert, edible medium that can be
cast into any desired shape (in our case, a goby fish), dyed various
colors, and be supplemented with edible material to introduce variation in
nutritional profiles. As such, Goby Gummies are a cheap, sustainable,
high-throughput assay that can be tailored to a variety of aquatic
ecosystems. We performed two pilot studies to test Goby Gummies in a
natural setting on coral reefs in Belize during which gummies were
reliably consumed by a range of predatory fishes. First, we show that
gummies supplemented with fish meal were preferred by predators over
agar-only gummies, but the strength of this preference was dependent on
their coloration, suggesting an intriguing interplay between external
appearance and internal composition. Second, we compared fish-supplemented
gummies to squidpops, a previously developed predation assay for marine
systems. Goby gummies were consumed first more frequently and eaten at
quicker rates than Squidpops and consistently attracted carnivorous
predators whereas squidpops were frequently consumed by herbivorous
parrotfishes. Our results highlight that Goby Gummies provide a new
predation assay tool in aquatic ecosystems that permits the exploration of
many exciting questions surrounding prey and predator traits and their
interplay. We envision goby gummies to kindle a diverse range of impactful
studies across disciplines that mirror those conducted in terrestrial
ecosystems.