Cruise Report Windward Caribbean Dec 3 – 20, 2018

Contributing Authors Dr. Stuart Sandin Dr. Brian Zgliczynski Lindsay Bonito

Scripps Institution of Oceanography

www.100islandchallenge.org Report prepared on 7 March 2019

Expedition Team

Scripps Institution of Oceanography Lindsay Bonito, Staff Researcher Sho Kodera, Staff Researcher

Caribbean Netherlands Science Institute (CNSI) Dr. Kimani Kitson-Walters, Data Monitoring Officer Anna Maitz, Research Staff

Nature Foundation St. Maarten Melanie Meijer zu Schlochtern, Project Officer Tadzio Bervoets, Researcher

Saba Bank National Park Ayumi Kuramae Izioka, Officer and Science Coordinator Joe Oliver, Boat Driver

Dive Support

Golden Rock Dive Center Sea Saba Dive Center

Executive Summary

In December 2018, the 100 Island Challenge team completed the second visit to the Windward Caribbean islands of Sint Eustatius, Sint Maarten, and Saba. These Dutch islands were first visited in 2016 during a ship-based expedition in collaboration with the Waitt Institute and local agencies including the Nature Foundation St. Maarten, Sint Eustatius National Parks Foundation (STENAPA), and Saba Bank National Park. Permanent monitoring sites were established at all islands, which were recovered and resurveyed in 2018.

Again, the 100IC partnered with each island’s local agencies with the addition of partners from Caribbean Netherlands Science Institute (CNSI) on St. Eustatius to resurvey 26 sites across the forereef of St. Maarten, St. Eustatius and Saba. Over the course of the 17-day expedition, the team recovered 18 of the 26 monitoring sites and re-established new sites where 2016 markers could not be found. Between the visits of 2016 and 2018, the islands were heavily impacted by the Hurricane Irma, Jose and Maria, particularly Sint Maarten, causing much damage to the islands and nearshore reef areas. Large boulders had been displaced, making site recovery and relocation very difficult. No permanent site markers were found at Sint Maarten, whereas nearly all sites were re-surveyed at Sint Eustatius and Saba. Fish and benthic surveys were conducted at all sites following GCRMN protocols to assess temporal change in communities over the course of two years. Three of nine temperature loggers were recovered, all of which showed a sharp decline in sea temperature immediately before Hurricane Irma, a commonly observed trend.

Through a visual comparison of the large-area images from Saba and Sint Eustatius, the reefs seemed to fair well despite the large hurricane disturbance in 2017. Controversially, reefs around Sint Maarten suffered greater hurricane damage, with a reduction in overall coral cover. Furthermore, divers found evidence of Stony Coral Tissue Loss Disease in Sint Maarten, a previously unknown coral disease originally identified in Florida and rapidly spreading throughout the Caribbean. The cause is unknown, but the disease affects many coral species including the slowest-growing and longest-lived reef-building corals. Fortunately, the disease had not yet been reported in Saba or Sint Eustatius.

100 Island Challenge

Description: This research initiative employs novel approaches for studying coral reef community dynamics through the application of underwater photomosaic technology. Working with colleagues from the University of Miami, we have built a camera system that allows us to capture images of large swaths of the reef surface. Further, by re- visiting exact locations multiple times and replicating photography, we have an unprecedented opportunity to track the dynamics of corals and algae. In particular, with advanced image analysis, we can track how a reef community changes, addressing questions of coral growth, death, and competition that are currently unresolved. We have field-trialed this photomosaic equipment and are developing a reliable image analysis protocol. We are now poised to apply this tool to generate the large-scale data of reef community dynamics that have to date been unavailable. Further, by combining these image-based data with reliable information about the composition of the fish community, the general oceanography, and the human situation of each location, we can begin to elucidate the conditions that are more (or less) conducive to the maintenance of growing and so-called ‘healthy’ coral reefs.

Application to the Caribbean: By linking the fates of these reefs to the oceanographic conditions and to the local activities of people, we will be able to start understanding cause-and- effect pathways for reef change. Given that local-scale marine managers consistently seek information on the ‘state’ of their coral reef, looking for comparisons to help guide local management. Further, by making the data that describe each reef readily available and easy to visualize, there is a terrific opportunity to increase the dialogue between the science and management communities, as well as independently among the managers looking for tangible information to improve their self-management. By working side-by- side with regional managers and partners in local NGOs (e.g., the Nature Conservancy, Conservation International), we will expand the scientific insights into the state and future of their reef areas.

For more information, visit www.100islandchallenge.org

Windward Caribbean Geography

Figure 1. Map of Sint Maarten, Sint Eustatius and Saba.

Survey Metadata

Table 1. Sites surveyed to assess fish and benthic communities during the Windward Caribbean 2018 expedition.

Area GCRMN Date Island Station ID Latitude Longitude Habitat Mosaic Divers1 Data2 Notes (m2) Divers1 2018-12-05 St. Eustatius STE_11 17.47057 -62.94862 100 Forereef SK, LTB, KKW MZS, AM B, F, M 2018-12-05 St. Eustatius STE_13 17.46240 -62.96883 100 Forereef SK, LTB, KKW MZS, AM B, F, M 2018-12-05 St. Eustatius STE_15 17.46778 -62.98346 100 Forereef LTB, SK, KKW MZS, AM B, F, M, T HOBO 10950547 2018-12-06 St. Eustatius STE_05B 17.50734 -62.97472 100 Forereef LTB, SK, KKW MZS, AM B, F, M 2018-12-06 St. Eustatius STE_07 17.50107 -62.96205 100 Forereef LTB, SK, KKW MZS, AM B, F, M 2018-12-06 St. Eustatius STE_100B 17.47956 -62.99461 100 Wreck SK, LTB, KKW - M 2018-12-07 St. Eustatius STE_01B 17.52648 -62.99709 100 Forereef SK, LTB, KKW MZS, AM B, F, M 2018-12-07 St. Eustatius STE_102 17.52553 -62.99962 100 Forereef LTB, SK, KKW MZS, AM B, F, M 2018-12-07 St. Eustatius STE_19 17.52122 -63.00087 100 Forereef SK, LTB, KKW MZS, AM B, F, M 2018-12-10 St. Maarten STM_107B 17.98897 -63.05897 100 Forereef SK, LTB, TB KKW, AM B, F, M 2018-12-10 St. Maarten STM_105B 17.99133 -63.05630 100 Forereef LTB, SK, TB KKW, AM B, F, M 2018-12-10 St. Maarten STM_110 18.01.280 -63.06.776 100 Backreef SK, LTB - M 2018-12-11 St. Maarten STM_16 18.00501 -63.04050 100 Forereef LTB, SK, MZS KKW, AM B, F, M 2018-12-11 St. Maarten STM_109 17.98815 -63.05157 100 Forereef SK, LTB, TB KKW, AM B, F, M 2018-12-12 St. Maarten STM_100 18.02297 -63.01254 100 Forereef SK, LTB KKW, AM B, F, M 2018-12-12 St. Maarten STM_101B 18.01023 -63.00787 100 Forereef LTB, SK KKW, AM B, F, M 2018-12-12 St. Maarten STM_104B 17.98824 -63.05149 100 Forereef SK, LTB KKW, AM B, F, M 2018-12-13 St. Maarten STM_19B 18.02310 -63.02615 100 Forereef SK, LTB, MZS KKW, AM B, F, M 2018-12-15 Saba SAB_02B 17.63698 -63.25600 100 Forereef SK, LTB, AI KKW, AM B, F, M 2018-12-15 Saba SAB_8B 17.64671 -63.25513 100 Forereef LTB, SK KKW, AM B, F, M 2018-12-15 Saba SAB_07 17.63116 -63.25766 100 Forereef SK, LTB KKW, AM B, F, M, T HOBO 10944802 2018-12-16 Saba SAB_08 17.64610 -63.25283 100 Forereef LTB, SK KKW, JO B, F, M, T HOBO 10944802 2018-12-16 Saba SAB_6B 17.61773 -63.25913 100 Forereef SK, LTB KKW, JO B, F, M 2018-12-16 Saba SAB_05 17.61252 -63.23670 100 Forereef LTB, SK KKW, JO B, F, M 2018-12-17 Saba SAB_04B 17.62862 -63.23007 100 Forereef SK, LTB KKW, JO B, F, M 2018-12-17 Saba SAB_01 17.65021 -63.23857 100 Forereef LTB, SK KKW, JO B, F, M

1 AI- Ayumi Izioka, AM- Anna Maitz, JO- Jens Odinga, KKW- Kimani Kitson-Walters, LTB – Lindsay Bonito, MZS- Melanie zu Meijer Schlochtern, SK – Sho Kodera, TB- Tadzio Bervoets

2 B- GCRMN benthic survey & photoquadrats, F- GCRMN fish survey, M-Mosaic, T-Temperature logger retrieved

Benthic Survey Methods

Large-Area Image Surveys

Benthic photomosaics were completed to collect a permanent record of reef habitat on a larger scale (100m2). The benthic photomosaic system consists of a diver operating a camera system including dual SLR cameras and video camera mounted to a custom frame. The first still camera is setup to use a wide-angle 18mm focal length lens to sure high overlap among adjacent images while the second still camera uses a 55mm focal length lens to capture images with sub-cm resolution. The high-resolution wide-angle video camera serves as a backup in the event that images from the still cameras are compromised. To obtain the large image covering 10m x10m the diver operating the camera system swims a gridded pattern approximately 1.5 m above the benthos recording images at 1 sec intervals throughout the plot. A pair of lasers is mounted within the frame of the 55mm camera to provide scale in the high-resolution imagery. Images are later stitched together analytically using custom algorithms to create a single image file representative of the 100m2 plot.

Figure 2. Photomosaic Data Collection Method. Each mosaic is stitched together from ~2000 photos acquired by swimming back and forth over the reef in the pattern on the left.

Figure 3. Photomosaic Processing Method. Once stitched, each mosaic is ecologically post-processed by tracing individual coral colonies and algae species of interest. Once individual colonies are traced and identified (E), data is exported and run through custom algorithms to evaluate both standard metrics including percent coral cover and more complex spatial statistics.

GCRMN Benthic Surveys Similar to the fish survey methods, benthic communities were characterized using a photoquadrat method, consistent with the Global Coral Reef Monitoring Network - Caribbean (GCRMN) guidelines for ecological monitoring. Digital photographs of the reef surface were taken in standardized quadrat areas (0.9m x 0.6m). Photographs are taken along each of the 5 transect lines set for counting fish, with 15 images captured per 30m transect line (i.e., one image taken at every 2m on the transect tape). In total, 75 benthic photographs were collected at each site (5 transect lines x 15 photographs per line). Images will be analyzed by overlaying 25 random points and identifying each organism or habitat feature associated with each point to the finest level of resolution possible (genus level for hard and soft corals, functional group for algal turfs and crustose coralline algae, and species level for macroalgae and macroinvertebrates when possible). Photoquadrat images will be analyzed for coral disease as well, in addition to in situ presence/absence surveys of disease within the transects. Coral recruitment was data in situ, with the goal of estimating the density of young corals that are likely to contribute to the next generation of adult corals on the reef. Coral recruits are defined operationally for this assessment as any stony coral that is greater than 0.5 cm and up to 4.0 cm. Estimates of coral recruit density were recorded from replicate 25cm x 25cm (625 cm2) quadrats. A total of 3 quadrats were surveyed along each transect used for benthic and fish surveys. The coral recruit quadrats will be placed at 10-meter intervals along the transect line, resulting in a total of 15 quadrats surveys per site (5 transect lines x 3 quadrats per line. Within each quadrat, each stony coral within the target size range (0.5 - 4.0 cm) were recorded to the finest taxonomic level possible (family, genus, or species). Additionally, in each coral recruitment quadrat, average turf height was also measured four times in the quadrat.

Fish & Macro-Invertebrate Survey Methods

Fish Assemblage Survey Methods Estimates of fish abundance and biomass were completed using methods consistent with the Global Coral Reef Monitoring Network - Caribbean (GCRMN) guidelines for ecological monitoring. In summary, All fish present (of all species) are counted and sized within a belt transect (30m length x 2m width), with the survey time limited to approximately 6 minutes per transect. At each site, at least 5 transects are surveyed and the data are pooled to provide an average estimate of the density and size structure of all fishes at the site. Fish are classified by size to the nearest 5cm bin.

Key Macro-Invertebrate Survey Methods The densities of the long-spined sea urchin (Diadema antillarum), other sea urchins, and all sea cucumbers were recorded in situ by the fish diver. Within 3 of the benthic transect lines, the diver counted invertebrates in the first 10m along the transect, within a 2m wide belt, giving a total area of 60m2.

Sea Temperature Survey Methods

Temperature Logger Deployment To collect environmental data pertaining to sea temperature, 4 temperature sensors were deployed at cardinal sites around the atoll. These sensors comprised of 3 HOBO temperature loggers as well as 1 SeaBird Technologies SBE-39 sensor. Instruments were secured to the reef using heavy-duty cable ties and stainless-steel rods hammered into the substrate. The instruments were deployed nearby or within the mosaic plot to facilitate marking the mosaic plot as well as recovery of instruments. The instruments were programmed to collect a discrete sample every 45 minutes.

Summary Findings The team was able to visit all sites established in 2016 over the course of three weeks. A total of 26 mosaic image sets were collected, with a subset of 18 of those being resurvey sites. Additionally, GCRMN fish and benthic surveys were conducted at 24 of those sites around the three islands. Finally, of the 9 sea temperature loggers (HOBO Pro Logger v2) that were deployed in 2016, 3 were recovered.

Figure 4. Sites surveyed in Windward Caribbean in 2018.

Oceanographic Results

Sea Temperature To place the surveyed reefs in an oceanographic context, temperature recorders have been deployed at a subset of the survey sites. Three temperature loggers (OnSet HOBO Pro Logger v2) were deployed at each of the islands for a total of nine recorders. Unfortunately, due to massive storm damage in fall 2017, only three of these temperature recorders were recovered, two at Saba and one at St. Eustatius. The loggers were programmed to sample the water temperature at a 45-minute interval over the two-year period to collect high-resolution in situ data.

All three loggers seasonal variability of ~2.5-3°C and interestingly, a striking dip in temperature immediately following Hurricane Irma in early September. This phenomenon has been well-described and can even be seen from satellite imagery1. The temperature data recorded a drop of 2°C after the passing of Hurricane Irma (Figure 5), potentially providing a reprieve for corals that may have been stressed from warmer sea temperatures2 in locations where storm damage was not as detrimental.

Figure 5. Sea temperature recordings at three sites in the Windward Caribbean from Nov 2016 to Nov 2018. Red hashed bar represents resident time of Hurricane Irma in St. Maarten.

1 Stramma, L., Cornillon, P., & Price, J. F. (1986). Satellite observations of sea surface cooling by hurricanes. Journal of Geophysical Research: Oceans, 91(C4), 5031-5035. 2 Manzello, D. P., Brandt, M., Smith, T. B., Lirman, D., Hendee, J. C., & Nemeth, R. S. (2007). Hurricanes benefit bleached corals. Proceedings of the National Academy of Sciences, 104(29), 12035-12039.

Photomosaic Results & Products All mosaic products will be available online both on the 100 Island Challenge website and through our public Google Drive. Below are links to the photomosaics and 3D model videos from the Windward Caribbean 2018 expedition.

100 Island Challenge | Website | Google Drive | YouTube Channel

Windward Caribbean Atoll Reefscape