National Coral Reef Monitoring Program

Climate Monitoring Brief: Flower Garden Banks National Marine Sanctuary

Coral reef at East Buoy 3 in the Flower Garden Banks

Coral reef at East Buoy 3 in the Flower Garden Banks


Atlantic Oceanographic & Meteorological Laboratory Coral Program
University of Miami Cooperative Institute of Marine and Atmospheric Science
National Oceanic Atmospheric Administration


N. Besemer, A. Palacio, A. Webb, K. Simmons, I. Enochs - March 2023

Mission

The AOML Coral Program tracks the status and trends of coral reef ecosystems of the U.S. Atlantic and Caribbean as part of the National Coral Reef Monitoring Program (NCRMP). This summary brief provides an overview of the most recent climate monitoring efforts at Flower Garden Banks National Marine Sanctuary (FGBNMS).

Expedition summary

Data collection summary

Subsurface temperature Subsurface temperature recorders (STRs) were recovered and redeployed at east and west bank transects, including 4 instruments rangin in depth from 20m to 35m (Fig. 1). In total, more than 4 million temperature observations were collected from 7 different instruments (Table 1).

Table 1: Number of temperature observations collected by transect and depth. Sites marked with NA were not sucessfully recovered
Transect 21m 25m 30m 35m Total
East 772,166 772,334 772,301 772,097 3,088,898
West NA 399,148 446,378 529,033 1,374,559

NCRMP Climate Fixed Sentinel Site Monitoring

At East Buoy 3, 20m site, located on the East Bank, short term instruments (72h) were deployed to monitor daily fluctuations in:


Habitat persistence

Changes in Bioerosion and accretion were monitored


Figure 1: Study sites and depths in Flower Garden Banks

Figure 1: Study sites and depths in Flower Garden Banks

Subsurface Temperature

The temperatures that marine organisms experience are a function of depth and local oceanographic conditions. To monitor this, two cross-shelf transects were established at each bank within the sanctuary. Three years of temperature measurements were retrieved and processed from eigth sites (depths). Each transect consists of STRs at 4 depths (20, 25, 30, 35m; Fig. 2). Temperature was measured using SeaBird Electronics Subsurface Temperature Recorders (STR)s that collected data at 5-minute intervals. The STRs from west bank were not able to be collected during the last field monitoring trip in 2019. Weve included the entire temperature data collectino from east bank for better comparison to west bank.

Figure 2: Temperature conditions at two transects in FGBNMS (east bank, and west bank) representing a depth gradient (20m, 25m, 30m and 35m). Data were collected from September 2015 to October 2022. However, STR from west Bank - 20m was not recovered.

Temperature values were lower in the deeper stations (30 and 35m) of both east and west banks. A particular cold winter was recorded in the year 2021, when monthly mean temperatures were below 20.6\(^\circ\)C at all depths. September of 2016 was the hottest month recorded in both banks, with mean temperatures higher than 30.76\(^\circ\)C) at the 21, 25 and 30m stations, and higher than 29.77\(^\circ\)C) at the 35m stations (Fig. 2).

Diurnal Suite Deployment

Seawater carbonate chemistry can fluctuate diurnally, due to biological forcing and processes such as photosynthesis and respiration, as well as calcification and dissolution. To characterize this, discrete water samples were collected at three-hour intervals (n=15) using Subsurface Automatic Samplers (SAS, https://www.coral.noaa.gov/accrete/sas/, Fig. 3). These samples will be analyzed for Total Alkalinity (TA), Dissolved Inorganic Carbon (DIC), and Spectrophotometric pH (SpecpH), which will be used to calculate pCO2 and aragonite saturation state (ΩAragonite).

A suite of instruments was deployed for a 72-hour period at the East Bank 20m site. A SeaFET was used to log pH, an EcoPAR measured Photosynthetically Active Radiation (PAR), and a Lowell Tiltmeter measured current speed and direction. Each collected measurements at 15-minute intervals (Fig. 3).

Figure 3: Data from East Buoy 3 diurnal suite monitoring from October 4th to Oct 7th. Top panel: pH and temperature from SeaFET. Bottom panel: Photosynthetically Available Radiation (PAR) and current speed from EcoPAR and Tiltmeter. Grey blocks denote night time throughout sequence of the plot. Instruments measured parameters every 15 minutes.

Habitat persistence

Carbonate budget assessments use transect-based surveys to quantify the abundance of carbonate producers, such as corals and crustose coralline algae, as well as carbonate bioeroders, such as grazing parrotfish and sea urchins. Abundances are multiplied by taxon- specific rates of carboante alteration to determine if a reef is in a state of net accretion (habitat growth) or net loss (habitat loss). At East Buoy 3, six transects were established and surveyed in 2015 to obtain carbonate budgets. We revisited this site in 2019 and 2022 to find out the new status of carbonate budget after six years.

While collecting this years data, divers noticed abundant signs of high bioerosion activity by parrot fish. Entire colonies were scraped away around the vicinity of East Buoy 3 and in other sites too. The increase in bioerosion rates in our records was due to the sighting of very large individuals across the transects which caused a 4-fold increase in rates of parrotfish bioerosion from 2019 to 2022. This, in addition with reduced coral cover, resulted in a decrease in net community calcification of more than 4kg m-2 yr-1. Macro bioerosion also increased significantly in the year 2022 which could either be due to an increase in the abundance of bioerosion sponges in the area or a bias between surveyors.

Figure 5: Carbonate budgets from East FGB in 2015, 2019 and 2022 and the processes contributing to calcification and bioerosion. The horizontal line in the “Net carbonate production panel” denotes accretionary stasis, the point where the budget flips from habitat grpwth to loss. PF represents parrotfish.

Landscape mosaics are used to quantify the benthic community, and to monitor changes in coral cover over time. Thousands of underwater images are digitally stitched together to create a high-resolution archive of the reef at the time of collection.

Figure 6: Landscape Mosaic collected from transect 6

Figure 6: Landscape Mosaic collected from transect 6

Finally, Calcification Accretion Units (CAUs) and Bioerosion Monitoring Units (BMUs) were used to investigate the balance between calcification and erosion. CAUs and BMUs were collected and redeployed for the next sampling cycle. CAUs are processed by the Pacific Climate group and the data will be available within a year. BMUs will be dried and cleaned using a hydrogen peroxide solution. These samples will be weighed and scanned using a CT scanner and then compared to their pre-scans to quantify bioerosion. Data will be available in a year. Please reference previous datasets for more information.

Figure 7: CAU and BMU pair before retreval after being deployed for three years. CAUs are two parallel PVC plates to quantify settled accretors. BMU is mounted coral skeleton installed at the base of the metal stake and has been encrusted.

Figure 7: CAU and BMU pair before retreval after being deployed for three years. CAUs are two parallel PVC plates to quantify settled accretors. BMU is mounted coral skeleton installed at the base of the metal stake and has been encrusted.

Rapid response to coral lesions

During a separate monitoring cruise that took place in August, an increase in coral lesions were noticed a variety of coral species which could be a possible signs of a coral disease outbreak. The climate monitoring on this cruise was completed efficiently to allow for some opportunistic sampling of the lesions. Coral samples were collected for histology (n= 99), and ’omics (n=100) analyses. Additionally, 13 live colonies were recovered to complete land based monitoring of lesion progression.

Figure 8: Colonies sowing lesions at the FGB.

Figure 8: Colonies sowing lesions at the FGB.

About the monitoring program

AOML’s climate monitoring is a key part of the National Coral Reef Monitoring Program of NOAA’s Coral Reef Conservation Program (CRCP), providing integrated, consistent, and comparable data across U.S. Managed coral reef ecosystems. NCRMP efforts aim to:

Point of Contact

Atlantic Climate Operations Coordniator:

Principal Investigator:

NCRMP Coordinator:

For more information

Coral Reef Conservation Program: http://coralreef.noaa.gov

NCRMP climate monitoring: https://www.coris.noaa.gov/monitoring/climate.html

NOAA Atlantic Oceanographic and Meteorological Laboratory: http://www.aoml.noaa.gov/

FGBNMS Reef Status Report 2020

National Coral Reef Status Report 2020

Acknowledgements

These efforts were jointly funded by NOAA’s CRCP project #743 and OAP. We would like to sincerely thank Flower Garden Banks and the National Marine Santuary Foundation for supporting our field efforts and assisting monitoring surveys.

Our Team

Flower Garden Banks 2022 Field team

Flower Garden Banks 2022 Field team

AOMLs NCRMP Atlantic and Caribbean Climate Team: I. Enochs, N. Besemer, G. Kolodziej, M. Chakraborty, A.Boyd, M. Jankulak, A. Palacio-Castro, A. Webb, B. Chomitz

Field team support and collaborators: M. Studivan, K. Eaton, M. Johnston, K. O’Connell