Project: The Role of Temperature in Regulating Herbivory and Algal Biomass in Upwelling Systems

Acronym/Short Name:Temperature and Herbivory
Project Duration:2017-08 - 2022-07

Description

NSF Award Abstract:
A well-known pattern in coastal marine systems is a positive association between the biomass of primary producers and the occurrence or intensity of upwelling. This is assumed to be caused by the increase in nutrient concentration associated with upwelling, enabling higher primary production and thus greater standing algal biomass. However, upwelling also causes large, rapid declines in water temperature. Because the metabolism of fish and invertebrate herbivores is temperature-dependent, cooler upwelled water could reduce consumer metabolism and grazing intensity. This could in turn lead to increased standing algal biomass. Thus upwelling could influence both bottom-up and top-down control of populations and communities of primary producers. The purpose of this study is to test the hypothesis that grazing intensity and algal biomass are, in part, regulated by temperature via the temperature-dependence of metabolic rates. Broader impacts include the training and retention of minority students through UNC's Course Based Undergraduate Research program, support of undergraduate research, teacher training, and various outreach activities.

The investigators will take advantage of the uniquely strong spatiotemporal variance in water temperature in the Galápagos Islands to compare grazing intensity and primary production across a natural temperature gradient. They will combine field monitoring, statistical modeling, grazing assays, populations-specific metabolic measurements, and in situ herbivore exclusion and nutrient addition to measure the effects of temperature on pattern and process in shallow subtidal communities. The researchers will also test the hypothesis that grazer populations at warmer sites and/or during warmer seasons are less thermally sensitive, potentially due to acclimatization or adaptation. Finally, the investigators will perform a series of mesocosm experiments to measure the effect of near-future temperatures on herbivores, algae, and herbivory. This work could change the way we view upwelling systems, particularly how primary production is regulated and the temperature-dependence of energy transfer across trophic levels.


DatasetLatest Version DateCurrent State
Results from predation assays (squidpops) conducted along rocky reefs of the Western coast of San Cristobal, Galapagos from June to November 2021 to determine fish predation intensity across a spatial and temporal temperature gradient 2024-05-17Final no updates expected
Results from mesocosm experiments measuring how temperature affects predation rates by whelks on barnacles2024-05-17Final no updates expected
Temperature data collected at Cerro Mundo Bay, San Cristobal, Galapagos from July 2019 to August 2022 using an Onset HOBO Water Temperature Pro v2 Data Logger2024-04-05Final no updates expected
Macroalgal biomass data (Preburn, Postburn, and Ash-Free Dry Weight) collected in the nearshore shallow subtidal during six field experiments conducted at Cerro Mundo Bay in the Galapagos Islands between July 2021 and May 20222023-04-18Final no updates expected
Pencil urchin respiration rates at different temperatures from four sites in the Galápagos archipelago2021-09-07Final no updates expected
Ocean temperature from Onset loggers at 7 sites in the Galápagos archipelago collected from March 2018 to August 20202021-01-27Final no updates expected
Experiment testing the temperature dependence of urchin grazing at the Galapagos Science Center on San Cristobal Island from February to March 20182019-08-20Final no updates expected
Species list from a fish survey conducted at five sites in the Galapagos Islands in March of 20182018-07-19Preliminary and in progress
Fish survey data from five sites in the Galapagos Islands in March of 20182018-07-18Preliminary and in progress

Project Home Page


People

Principal Investigator: John Bruno
University of North Carolina at Chapel Hill (UNC-Chapel Hill)

Contact: John Bruno
University of North Carolina at Chapel Hill (UNC-Chapel Hill)


Data Management Plan

DMP_Bruno_OCE-1737071.pdf (13.34 KB)
02/09/2025