Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
• Related Publications
• Related Datasets
• Parameters
• Project Information
• Funding

See "Related Datasets" section for other datasets to be published in Ng & Gaylord (2025, in-prep).  These datasets are also listed on the "Related-Resource" page for that results publication https://www.bco-dmo.org/related-resource/948176
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All datasets in this project can be viewed from the "Dataset Collections" of the project page https://www.bco-dmo.org/project/712799

To examine the intensity of anti-predatory behavior of both Tegula funebralis and Nucella lamellosa, we measured the proportion of time individual snails spend above the waterline in the presence and absence of their predator species, Pisaster ochraceus and Cancer productus. Data from this experiment are used to calculate estimated predation rates for snails that do not behaviorally respond to their predators, which are used to determine the impact anti-predatory responses have on the strength of trophic cascades. The experiment was conducted within laboratory mesocosms at Bodega Marine Lab in 2018 and 2019.

Pisaster ochraceus, Cancer productus, and Tegula funebralis were collected along the coastline of Sonoma County, California in 2018. Both Pisaster and Tegula were sampled at Carmet Beach (38.372172 N, -123.076438 W), and the Cancer crabs were gathered subtidally from Doran Beach (38.309334 N, -123.048703 W). Nucella lamellosa were collected at Washington Park in Anacortes, Washington (48.502190 N, -122.691865 W) in July 2019.

We measured the behavior of both Nucella and Tegula in the presence and absence of their respective predators. We established 20 mesocosms (33cm x 20cm x 11.5cm) each with 10 Tegula that were provided with Ulva sp. ad libitum. Half of the mesocosms were exposed to Pisaster cue and the other 10 to just seawater. Predator exposure was accomplished by placing an individual Pisaster in a separate container, and then allowing cue generated by it to flow into the appropriate mesocosms. Pisaster were fed an individual Tegula once a week. Over a period of 14 days, we measured the number of snails either above or below the water line. Ulva sp. was included in the experiment in case its presence affected the snails’ decision to leave the water. We used the same procedure with Cancer to estimate Tegula’s behavioral response to them. We also used an analogous procedure to estimate Nucella’s behavioral response to Pisaster, with the exception that only five snails were used in each mesocosm due to the larger sizes of individuals of this snail species, and a small rock with Balanus glandula replaced Ulva as the basal resource.

Because a subset of our Nucella displayed morphological inducible defenses from the induction period, we also crossed the Pisaster cue treatment with the induced morphology treatment such that of the 10 mesocosms experiencing Pisaster cues, half of them contained induced Nucella and the other half had non-induced Nucella. Of the 10 mesocosms with no predator cue, half had induced Nucella and the other half had non-induced individuals.

To test the effect of predator cue on the snails’ behavior, we conducted a logistic regression on the proportion of snails in and out of the water line with container as a random effect. For Nucella, we also added induced morphology as a predictor along with its interaction with Pisaster cue, but because both terms were non-significant, we removed them from the final model. In addition, we added the containers they were housed in during the induction period as an additional random effect.

Organism identifiers (taxonomic names used in dataset metadata):

Scientific Name, Life Science Identifier (LSID)
Tegula funebralis, urn:lsid:marinespecies.org:taxname:534190
Nucella lamellosa, urn:lsid:marinespecies.org:taxname:404218
Pisaster ochraceus,urn:lsid:marinespecies.org:taxname:240755
Cancer productus,urn:lsid:marinespecies.org:taxname:440382
Ulva sp., urn:lsid:marinespecies.org:taxname:144296
Balanus glandula, urn:lsid:marinespecies.org:taxname:394848

NSF Award Abstract:
The absorption of human-produced carbon dioxide into the world's oceans is altering the chemistry of seawater, including decreasing its pH. Such changes, collectively called "ocean acidification", are expected to influence numerous types of sea creatures. This project examines how shifts in ocean pH affect animal behavior and thus interactions among species. It uses a case study system that involves sea star predators, snail grazers that they eat, and seaweeds consumed by the latter. The rocky-shore habitats where these organisms live have a long history of attention, and new findings from this work will further extend an already-large body of marine ecological knowledge. The project provides support for graduate and undergraduate students, including underrepresented students from a nearby community college. The project underpins the development of a new educational module for local K-12 schools. Findings will moreover be communicated to the public through the use of short film documentaries, as well as through established relationships with policy, management, and industry groups, and contacts with the media.

Ocean acidification is a global-scale perturbation. Most research on the topic, however, has examined effects on single species operating in isolation, leaving interactions among species underexplored. This project confronts this knowledge gap by considering how ocean acidification may shift predator-prey relationships through altered behavior. It targets as a model system sea stars, their gastropod grazer prey, and macoalgae consumed by the latter, via four lines of inquiry. 1) The project examines the functional response of the focal taxa to altered seawater chemistry, using experiments that target up to 16 discrete levels of pH. This experimental design is essential for identifying nonlinearities and tipping points. 2) The project addresses both consumptive and non-consumptive components of direct and indirect species interactions. The capacity of ocean acidification to influence such links is poorly known, and better understanding of this issue is a recognized priority. 3) The project combines controlled laboratory experiments with field trials that exploit tide pools and their unique pH signatures as natural mesocosms. Field tests of ocean acidification effects are relatively rare and are sorely needed. 4) A final research phase expands upon the above three components to address effects of ocean acidification on multiple additional taxa that interact in rocky intertidal systems, to provide a broad database that may have utility for future experiments or modeling.