Contributors | Affiliation | Role |
---|---|---|
Silbiger, Nyssa | California State University Northridge (CSUN) | Principal Investigator |
Adam, Tom C. | University of California-Santa Barbara (UCSB) | Scientist |
Becker, Danielle M. | California State University Northridge (CSUN) | Scientist, Student, Contact |
Burkepile, Deron | University of California-Santa Barbara (UCSB) | Scientist |
Putnam, Hollie | University of Rhode Island (URI) | Scientist |
Vega Thurber, Rebecca | Oregon State University (OSU) | Scientist |
York, Amber D. | Woods Hole Oceanographic Institution (WHOI BCO-DMO) | BCO-DMO Data Manager |
See the "Related Datasets" section or the project page for other data collected as part of this study.
See the Project Page for more data collected as part of the project.
Our study was conducted following 15 months of nutrient enrichment during October 2019 at the control and nutrient-enriched sites on the north shore fore reef habitat in Mo'orea. We collected fragments of Pocillopora meandrina at each site based on morphological characteristics. However, due to recent analyses on the complexity of Pocillopora spp. identification, morphological characteristics are unreliable for species identification. Therefore, the coral fragments will be referred to as Pocillopora spp. for the remainder of the methods. Thirty-two Pocillopora spp. colonies showing no signs of bleaching were haphazardly collected in a block design with four fragments collected from each of four treatment or control blocks from depths of ~ 13 m. The treatment coral fragments were collected within < 0.5 m the nutrient diffusers for the nutrient-enriched treatment (n = 16) and ~ 20 m away from the diffusers for the control (n = 16) on October 15, 2019. Pocillopora spp. fragments were removed with hammer and chisel via SCUBA, placed in clean ziplock bags full of seawater, and returned to the boat.
The coral fragments for physiological assays were transported to the UCB Gump Station in a seawater filled cooler and immediately placed in flow-through seawater tables. Using a stainless steel diagonal cutter, fragments of each sample colony were cut into five replicate dimensions (7.8 cm × 7.8 cm) of multi-branch fragments, which were measured with calipers . Two fragments were used for light and dark respirometry trials, and two fragments were used for endosymbiont and coral response variables, including chlorophyll a content, endosymbiont densities, endosymbiont % nitrogen (N) content, endosymbiont N cell−1, tissue biomass, and coral tissue % N content.
The two fragments designated for photosynthesis and respiration trials were affixed to pre-labeled acrylic coral plugs (Industry, CA, USA) using hot glue around the base of the coral skeleton while the fragment was submerged. After coral fragments were affixed, they were placed into one of two flow-through holding tanks (either control or nutrient-enriched) with filtered (pore size ~ 100 µm) seawater to recover from the fragmentation process for 7–12 days. The coral plugs were placed in individual holes on an acrylic sheet with an O-ring placed around the bottom of the plug for stabilization. The acrylic bases had 4 small 15-cm tall PVC pipes on the four corners of the base to keep the corals from being in contact with the bottom of the tank. Holding tank conditions were designed to mimic temperature and light regimes found at the collection sites.
Holobiont metabolic response variables
Acute heat ramping experiments were used to assess net photosynthesis (n = 32) or dark respiration (n = 32) of replicate fragments from each coral colony. To measure net photosynthesis (NP) and dark respiration (Rd), coral fragments were placed in individual closed-system acrylic respiration chambers (650 ml) (Australian Institute of Marine Science, Townsville, Australia) with rotating stir bars (200 rpm) (Fig. 1j). Filtered (pore size ~ 100 µm) seawater was used for all experimental assays. Eight experimental coral fragments were moved from their ambient and nutrient-enriched seawater flow-through holding tanks (4 enriched and 4 control) and randomly assigned to one of the 10 respirometry chambers. Replicate seawater-only chambers were used as controls (n = 2) for background subtraction during each trial (n = 4 NP trials, n = 4 Rd trials). Each of the Rd heat ramping experiments began at approximately 05:30, and corals were kept in complete darkness by a black tarp cover and black trash bag covers on all windows or doors. The Rd corals were exposed to ten sequential temperatures (20, 22, 24, 28, 30, 32, 34, 36, 37, and 38 °C) for 20 min. Following the same experimental design, the light ramp trials began at approximately 13:00 and ended before sunset. During each light ramp trial, the coral fragments were exposed to nine sequential temperatures (20, 22, 24, 28, 30, 32, 34, 36, and 37 °C) for 20 min at saturating light. One less temperature ramp was required for the light trials because corals exhibited near zero oxygen production at 37 °C.
To maintain the assay temperature (± 0.1 °C), temperature was controlled in an insulated reservoir and holding tank using a thermostat system (Apex Controller, Neptune Systems, Morgan Hill, CA, USA) paired with aquarium heaters (Finnex 800 W Titanium Heater, Finnex 300 W Titanium Heater, Burnaby, British Columbia, Canada) and chillers (Aqua Logic Delta Star®, DS-4, San Diego, CA, USA). An air stone diffuser (Growneer, Shanghai, China) was added to the holding tank where the chambers were filled before each temperature ramp to provide circulation and oxygenation. Further, fresh seawater changes were conducted between each temperature ramp. Once the seawater in the insulated reservoir reached a stable temperature, the respirometry chambers containing both the coral fragments and controls were added and measurements started immediately. NP and Rd rates were quantified through oxygen production/consumption measured by fiber optic oxygen sensors using Presens Oxygen Meter (OXY-10 SMA (G2) Regensburg, Germany) system with temperature correction for each channel separately. Temperature (°C) and oxygen concentrations (µmol L−1) were measured using Presens Temperature (Pt1000, Regensburg, Germany) and Presens Oxygen Dipping Probes (DP-PSt7, Regensburg, Germany) (company two-point calibration with oxygen-free environment [nitrogen, sodium sulfite] and air-saturated environment), respectively, at a frequency of 1 Hz. Gross photosynthesis (GP) was calculated as NP plus Rd (as a positive value). After each incubation, we removed all coral tissue, dried the coral skeletons, and measured the surface area of each coral using the paraffin wax dipping technique described above to normalize the rates (μmol cm−2 h−1)
Organism Life Science Identifiers (LSIDs):
Pocillopora meandrina, urn:lsid:marinespecies.org:taxname:206964
Pocillopora spp., urn:lsid:marinespecies.org:taxname:206938
All data and code are available at https://github.com/daniellembecker/Chronic_low_nutrient_enrichment_benefits_coral_thermal_performance_fore_reef_habitat (Release: v1.0.0 archival copy doi: 10.5281/ZENODO.5013255).
* Table within submitted file "Respirometrydata.csv" was imported into the BCO-DMO data system for this dataset. Values "NA" imported as missing data values.Table will appear as Data File: 960144_v1_coral-respirometry.csv (along with other download format options).
* BCO-DMO requires each column contain an individual measurement type (and units consistent per column). In order to meet this requirement, the BCO-DMO data manager transformed the data table and worked with the data contributor to review and make any additional changes needed. The original data format "Respirometrydata.csv" provided to BCO-DMO was included as supplemental file 960144_v1_coral-respirometry-alternate-format.csv
Transformation notes (going from the originally provided file "Respirometrydata.csv" to primary data table format 960144_v1_coral-respirometry.csv) :
* A table pivot was performed (transforming columns rate_type, umol_cm2_hr, and Temp_C) to separate sets of columns per rate type.
* To do this tables were separated by filtering on rate_type (R, NP, GP). Then joined to combine all columns using full joins on unique keys ("Fragment_ID", "Temperature_category", "treatment").
** Data were evaluated to determine a unique set of columns corresponding to the rate_type. ("Fragment_ID", "Temperature_category", "treatment") were unique per rate_type and Temp_C was variable for every type of rate measurement so it was included as separate columns R_Temp_C, NP_Temp_C, etc. (See Parameters section for column descriptions).
Missing Data Identifiers:
* In the BCO-DMO data system, missing data identifiers are displayed according to the format of data you access. For example, in csv files it will be blank (null) values. In Matlab .mat files it will be NaN values. When viewing data online at BCO-DMO, the missing value will be shown as blank (null) values.
* Column names adjusted to conform to BCO-DMO naming conventions designed to support broad re-use by a variety of research tools and scripting languages. [Only numbers, letters, and underscores. Can not start with a number]
* Organism names in this dataset were matched to Life Science Identifiers (LSIDs) using the World Register of Marine Species (WoRMS) on 2025-05-06.
Parameter | Description | Units |
Fragment_ID | Unique Fragment ID | unitless |
Temperature_category | Temperature category for thermal performance curve (enriched or control, see methology) | unitless |
treatment | Nutrient treatment (enriched = nutrients added; cocntrol = control) | unitless |
Temp_C | Temperature in respirometry chamber | degrees celcius (degC) |
umol_cm2_hr | metabolic rate | micromoles of O2 per square centimeter per hour (umol O2/cm2/hr) |
rate_type | Rate type (R = Respiration, GP = Gross Photosynthesis, NP = Net Photosynthesis) | unitless |
Dataset-specific Instrument Name | Presens Oxygen Dipping Probes (DP-PSt7, Regensburg, Germany) |
Generic Instrument Name | Oxygen Sensor |
Dataset-specific Description | Temperature (°C) and oxygen concentrations (µmol L−1) were measured using Presens Temperature (Pt1000, Regensburg, Germany) and Presens Oxygen Dipping Probes (DP-PSt7, Regensburg, Germany) (company two-point calibration with oxygen-free environment [nitrogen, sodium sulfite] and air-saturated environment) for respirometry measurements. |
Generic Instrument Description | An electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed |
Dataset-specific Instrument Name | Presens Temperature (Pt1000, Regensburg, Germany) |
Generic Instrument Name | Water Temperature Sensor |
Dataset-specific Description | Temperature (°C) and oxygen concentrations (µmol L−1) were measured using Presens Temperature (Pt1000, Regensburg, Germany) and Presens Oxygen Dipping Probes (DP-PSt7, Regensburg, Germany) (company two-point calibration with oxygen-free environment [nitrogen, sodium sulfite] and air-saturated environment) for respirometry measurements. |
Generic Instrument Description | General term for an instrument that measures the temperature of the water with which it is in contact (thermometer). |
NSF Award Abstract:
Submarine groundwater discharge (SGD) is the flow of water from land through the coastal seafloor into the nearby ocean. Approximately 13,000 cubic kilometers of groundwater is discharged into coastal environments every year, yet the effects of this fresh and often nutrient rich SGD are still poorly understood for coral reefs. This SGD input is driven by changes in precipitation, human land use, sea-level rise, tidal amplitude, and groundwater usage, many of which are rapidly changing with climate and human impacts. This project improves our understanding of SGD effects on coral reefs to better predict how both natural and human-induced changes will affect coastal ecosystem functioning in the future. Working in one of the most comprehensively studied coral reef ecosystems in the Pacific (Mo'orea, French Polynesia, home of the Mo'orea Coral Reef Ecosystem LTER); this project tests the influence of SGD on individual, community, and ecosystem-scale coral reef processes. Using mensurative studies, caging experiments, and a synthetic model, the investigators: 1) characterize SGD gradients and relate it to high resolution coral reef cover data, 2) determine how individual to ecosystem processes are influenced by SGD, and 3) develop a synthetic model to show how changes in SGD fluxes will alter reef ecosystem functioning. As SGD is a common feature on nearshore coral reefs worldwide, the results of this study have global implications for understanding the performance of coral reefs, which are essential economic, cultural, and scientific resources. This project is structured to provide training across multiple career levels, linking 13 undergraduate students, 2 graduate students, 2 senior personnel, 1 postdoctoral researcher, 1 female beginning lead investigator, and 2 senior co-investigators, with a focus on encouraging participation from underrepresented groups (e.g., through the Alaska Native and Native Hawaiian, Asian American and Native American Pacific Islander, and Hispanic-Serving Institutions of California State University Northridge, the University of Hawaiʻi at Mānoa, and California State University Long Beach). The investigators work with local K-12 students and teachers in Mo'orea and collaborate with an artist-in-residence to communicate science to the broader public through interactive and immersive art experiences in Mo'orea, Miami, and Los Angeles.
SGD is a natural and understudied feature of many nearshore coral reef ecosystems, which can contribute substantial changes to marine biogeochemistry, with impacts for coastal organisms such as reef-building corals, macroalgae, and bioeroders. SGD may play a key role in coral reef ecosystem functioning because it alters key physicochemical parameters (e.g., temperature, salinity, and nutrient and carbonate chemistry) that substantially affect both biotic and abiotic processes on coral reefs. This project (i) characterizes the spatial extent and biogeochemical signal of SGD in Mo'orea, French Polynesia, (ii) identifies how SGD influences microbial processes, benthic organism growth rates and physiology, species interactions between corals, macroalgae, and herbivores, and net ecosystem calcification and production rates, and (iii) quantitatively assesses how changes in SGD fluxes will alter reef biogeochemistry and ecosystem functioning through an integrative modelling effort. Specifically, the hydrogeological, biogeochemical, and ecological data collected in this study are synthesized in a Bayesian structural equation model. This project characterizes and quantifies how SGD directly and indirectly affects ecosystem functioning via changes in biogeochemistry and altered individual to ecosystem responses, thereby providing a better capacity to track and predict alterations in reef ecosystem function.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Funding Source | Award |
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NSF Division of Ocean Sciences (NSF OCE) |