Cruise Report Tuamotus & Line Islands

Transcription

1 Cruise Report Tuamotus & Line Islands August 21 September 2, 2017 Contributing Authors Dr. Stuart Sandin 1 Dr. Brian Zgliczynski 1 Lindsay Bonito 1 1 Scripps Institution of Oceanography Report prepared on 22 August

2 Expedition Team Scripps Institution of Oceanography Dr. Stuart Sandin, Professor Dr. Brian Zgliczynski, Postdoctoral Researcher Nicole Pedersen, Staff Researcher Chris Sullivan, Staff Researcher Waitt Institute Joe Lepore, Diving Safety Officer Shayna Brody, Social Media & Outreach, Photographer Cook Islands Korero O Te 'Orau Dr. Teina Ronga, Marine Ecologist James Kora, Research Assistant Center for Insular Research and Observatory of the Environment (CRIOBE) Charlotte Moritz, Postdoctoral Research Scholar The Nature Conservancy Hank Lynch, Scientific Diver 2

3 Executive Summary Members of the 100 Island Challenge team (Nicole Pederson, Chris Sullivan, Stuart Sandin, and Brian Zgliczynski) returned from an expedition this past August to survey coral reefs at a subset of atolls in the Tuamotu Archipelago, French Polynesia, as well as re-visit several islands in the Southern Line Islands, Republic of Kiribati. This expedition was supported by the Waitt Institute and represented a collaborative effort between the Scripps Institution of Oceanography, Waitt Institute, Center for Insular Research and Observation of the Environment (CRIOBE - French Polynesia), Korero O Te Orau - Cook Islands, and The Nature Conservancy Hawaii. The goal of the 14-day expedition was to characterize coral reef communities as part of the 100 Island Challenge. The coral reefs of the Tuamotu Archipelago and Southern Line Islands are remote and relatively free of direct human influence. Therefore, they provide researchers with an opportunity to study intact ecosystems with thriving coral and fish communities. Although this was the first opportunity to visit sites in the Tuamotus as part of the 100 Island Challenge, our team has conducted multiple survey efforts to the Southern Line Islands over the past several years. This expedition was particularly important because it provided our team with an opportunity to investigate the status of coral reefs of the region in conjunction with reports of widespread coral bleaching across the Pacific. By establishing new survey sites and re-visiting long-term sites are team will contextualize changes in coral reef communities through time and gain invaluable information on how these diverse ecosystems respond to recent warm water events. The team was excited to visit these sites but there was some apprehension over what they would find. Would the coral reefs of these islands be another casualty of the global mass-bleaching event? Upon entering the water, the team was filled with mixed emotions. Preliminary observations revealed that the reefs had been impacted by the warm water events. However, the magnitude appeared to be species-specific and variable across islands. For example, fast growing species appeared to be hit the hardest while slower-growing species appeared to be impacted to a lesser extent. While the observed mortality was discouraging the team was excited to see evidence of recovery and regrowth. Corals that had recently died were being overgrown with coralline algae, an important reef builder that strengthens the reef and provides substrate for new corals to settle and attach. Additionally, the team observed healthy populations of reef fishes including predatory species like jacks, snappers, and sharks as well as abundant populations of smaller-bodied species that are important food sources for predators. Overall, the expedition represented a successful collaborative effort and the team gained valuable insight into the structure and function of coral reefs in the two regions. During the 14-day expedition, the team conducted over 300 scientific dives across 8 islands (Millennium, Flint, Vostok, Takapoto, Tikehau, Rangiroa). These dives were comprised of 47 total photomosaic benthic surveys (14 resurveys of permanent sites) and 59 reef fish surveys. This high level of productivity could not have been possible without the hard work and efficiency of the crew of the Plan B. 3

4 100 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 revisiting 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 French Polynesia & Line Islands: 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 4

5 Tuamotus & Line Islands Background Figure 1. Map of French Polynesia & Line Islands. The Tuamotu archipelago is a French Polynesian chain of almost 80 islands and atolls with a land area of 850 km 2 and 16,000 inhabitants. Its major islands are Anaa, Fakarava, Hao and Makemo. The Line Islands is a chain of 11 atolls (with partially or fully enclosed lagoons) and coral islands (with a surrounding reef) spanning 2,350 kilometres. Of the 11 islands/atolls, 8 form part of Kiribati, while the remaining 3 are United States territories grouped with the United States Minor Outlying Islands. Only Kiritimati and Tabuaeran atolls and Teraina Island have a permanent population. 5

6 Survey Metadata Table 1. Sites surveyed to assess fish and benthic communities in Island Station ID Date Local Time Latitude Longitude Area (m 2 ) Habitat Mosaic Divers 1 Fish Divers 1 Data Collected 2 Tikehau TIK : Forereef CS, NP, TR, JK NA M Tikehau TIK_ : Forereef CS, NP, TR, JK NA M Tikehau TIK_ : Forereef CS, NP, TR, JK NA M, T Tikehau TIK_ : Forereef NA BZ, SAS, HL, CM F, B Tikehau TIK_ : Forereef NA BZ, SAS, HL, CM F, B Tikehau TIK_ : Forereef NA BZ, SAS, HL, CM F, B Tikehau TIK_ : Forereef NP, TR SAS, HL F, B, M Tikehau TIK_ : Forereef CS, JK BZ, CM F, B, M, 360 Tikehau TIK_ : Forereef NP, TR SAS, HL F, B, M, T Tikehau TIK_ : Forereef CS, JK BZ, CM F, B, M, 360 Tikehau TIK_ : Forereef NP, TR SAS, HL F, B, M, T Tikehau TIK_CRIOBE : Forereef CS, JK BZ, CM F, B, M, 360 Millennium MIL_C : Forereef CS, JK BZ, CM F, B, M, 360 Millennium MIL_C : Forereef NP, TR SAS, HL F, B, M Millennium MIL_ : Forereef CS, JK BZ, CM F, B, M, 360 Millennium MIL_C : Forereef NP, TR SAS, HL F, B, M Millennium MIL_ : Forereef CS, JK BZ, CM F, B, M, 360

7 Island Station ID Date Local Time Latitude Longitude Area (m 2 ) Habitat Mosaic Divers 1 Fish Divers 1 Data Collected 2 Millennium MIL : Forereef NP, TR SAS, HL F, B, M, T Millennium MIL_C : Forereef NP, TR SAS, HL F, B, M Millennium MIL_ : Forereef NP, TR SAS, HL F, B, M Millennium MIL_ : Forereef NP, TR SAS, HL F, B, M, T Millennium MIL_C : Forereef CS, JK BZ, CM F, B, M, 360 Millennium MIL_C : Forereef CS, JK BZ, CM F, B, M, 360 Millennium MIL_ : Forereef CS, JK BZ, CM F, B, M, 360 Millennium MIL_C : Forereef CS, JK BZ, CM F, B, M Millennium MIL_ : Forereef CS, JK BZ, CM F, B, M, 360, T Millennium MIL_C : Forereef NP, TR SAS, HL F, B, M Millennium MIL_C : Forereef NA SAS, HL F, B Millennium MIL_ : Forereef NP, TR NA M Vostok VOS_ : Forereef NP, TR SAS, HL F, B, M Vostok VOS_ : Forereef NP, TR SAS, HL F, B, M, T Vostok VOS_ : Forereef CS, JK BZ, CM F, B, M, 360, T Vostok VOS_ : Forereef CS, JK BZ, CM F, B, M, T Flint FLI_ : Forereef CS, JK BZ, CM F, B, M, T Flint FLI_ : Forereef CS, JK BZ, CM F, B, M, T 2

8 Island Station ID Date Local Time Latitude Longitude Area (m 2 ) Habitat Mosaic Divers 1 Fish Divers 1 Data Collected 2 Flint FLI_ : Forereef CS, JK SAS, HL F, B, M, T Rangiroa RAN_ : Forereef CS, JK BZ, CM F, B, M, 360 Rangiroa RAN_ : Forereef CS, JK BZ, CM F, B, M, 360 Rangiroa RAN_ : Forereef CS, JK BZ, CM F, B, M Rangiroa RAN_ : Forereef CS, TR SAS, HL F, B, M, 360, T Rangiroa RAN_ : Forereef NA SAS, HL F, B Rangiroa RAN_ : Forereef NA SAS, HL F, B Rangiroa RAN_ : Forereef NA SAS, HL F, B Takapoto TAK_ : Forereef CS, JK BZ, CM F, B, M, 360 Takapoto TAK_ : Forereef CS, JK BZ, CM F, B, M Takapoto TAK_ : Forereef CS, JK BZ, CM F, B, M Takapoto TAK_ : Forereef BZ, CS SAS, HL F, B, M, 360 Takapoto TAK_ : Forereef NA SAS, HL F, B Takapoto TAK_ : Forereef NA SAS, HL F, B Takapoto TAK_ : Forereef NA SAS, HL F, B Takapoto TAK_ : Forereef CS, JK BZ, CM F, B, M Takapoto TAK_ : Forereef CS, JK BZ, CM F, B, M Takapoto TAK_CRIOBE : Forereef CS, JK BZ, CM F, B, M, 360, T 3

9 Island Station ID Date Local Time Latitude Longitude Area (m 2 ) Habitat Mosaic Divers 1 Fish Divers 1 Data Collected 2 Takapoto TAK_ : Forereef BZ, CS SAS, HL F, B, M, T Takapoto TAK_ : Forereef NA SAS, HL F, B Takapoto TAK_ : Forereef NA SAS, HL F, B Takapoto TAK_ : Forereef NA SAS, HL F, B Rangiroa RAN_ : Forereef CS, JK BZ, CM F, B, M Rangiroa RAN_ : Forereef CS, JK BZ, CM F, B, M Rangiroa RAN_ : Forereef CS, JK BZ, CM F, B, M, 360, T Rangiroa RAN_ : Forereef NA SAS, HL F, B Rangiroa RAN_ : Forereef NA SAS, HL F, B Rangiroa RAN_ : Forereef NA SAS, HL F, B 1 Divers: CS- Chris Sullivan; CM- Charlotte Moritz, HL- Hank Lynch; JK- James Kora; TR- Teina Ronga; BZ- Brian Zgliczynski; NP- Nicole Pedersen; SAS- Stuart Sandin 2 Data Collected: F- Fish; B-Benthic photoquadrats; M-Mosaic; T- temperature logger deployed; video 4

10 Benthic Photomosaic Survey Methods Benthic photomosaics were completed to collect a permanent record of reef habitat on a larger scale (100m 2 ). 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 100m 2 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.

11 Summary Findings Figure 4. Sites surveyed at Millennium Atoll during the Tuamotus and Line Islands expedition in

12 Summary Findings Figure 5. Sites surveyed at Vostok and Flint Islands during the Tuamotus and Line Islands expedition in

13 Summary Findings Figure 6. Sites surveyed at Tikehau Island during the Tuamotus and Line Islands expedition in

14 Summary Findings Figure 7. Sites surveyed at Rangiroa Island during the Tuamotus and Line Islands expedition in

15 Summary Findings Figure 8. Sites surveyed at Takapoto Island during the Tuamotus and Line Islands expedition in

16 Sample Mosaic Site: MIL_03 Island: Millennium Atoll Date: August 26, 2017 Notes: 100m 2 plot on forereef 7

17 Photomosaic Results & Products All mosaic products are 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 2017 expedition. 100 Island Challenge Google Drive 100 Island Challenge YouTube Channel 2D Orthophotos & 3D Model Videos Tuamotus & Line Islands 2017 Google Drive YouTube Playlist 8