Lead: Jennifer Appoo
Former Science and Project Coordinator at Seychelles Island Foundation
Aldabra has the highest diversity and abundance of top marine predators in the southern Seychelles due to decades of strict protection. Top predators such as sharks and large groupers are key ecological indicator species for monitoring conservation efforts and success on Aldabra. Some of these species have wide depth ranges during their lifetime, playing a role in connectivity between shallow and deep waters. Baited Remote Underwater Video (BRUV) survey is an integral part of the long-term Aldabra Reef Monitoring programme, and aims to assess fish community assemblages around the atoll but is limited to shallow waters (< 50m). Aldabra’s deep-sea communities were explored for the first time in March 2019 during the Nekton Deep Sea expedition and the fish community was assessed down to a maximum depth of 250m. This project aimed to combine BRUV data together with data collected from the Nekton expedition to obtain for the first time a comprehensive baseline of the marine predator community around Aldabra from the shallow to the deep sea. A second goal was to identify the depth ranges of these marine predators providing an indication on the levels of connectivity between shallow and deep-sea ecosystems around the atoll. The project was therefore a collaboration between the two key partners, the Seychelles Islands Foundation and the Nekton Foundation.
Furthermore, the marine environment within the near-shore of Aldabra’s marine protected area (MPA) is zoned according to three management zones, (1) tourism zones where tourism activities are allowed; (2) food security zones where subsistence fishing is allowed; and (3) conservation or no take areas all activities are prohibited (Figure 2). BRUV data aims to assess the impacts of localised subsistence fishing on Aldabra’s fish community, especially predator assemblage, and to develop adaptive management strategies to mitigate any negative impacts. This type of zoning strategy within an MPA is the first in Seychelles and represents a model example for sustainable fisheries management in the country. The programme is already in place but, given Aldabra’s size, additional BRUV equipment was needed to increase efficiency and scope of the sampling plan and data collection. The research grant was aimed at providing funds to support and improve the Aldabra BRUV data collection programme through sourcing of additional equipment. Moreover, due to lack of capacity, time and analytical skills within the organisation, the data collected from BRUV surveys had not yet been analysed in depth. The research project was also aimed at conducting an in-depth analysis of the BRUV dataset to determine the effectiveness of the zoning strategy.
Overall, the research project aimed to contribute to strengthening marine research, conservation and management efforts of Aldabra and provide valuable information for ocean governance, especially fisheries management for Aldabra and other areas in Seychelles.
- Aldabra BRUV survey was successfully completed by SIF in January 2019 and 17 1-hour videos were collected between 5 and 50m.
- The Nekton Deep Sea expedition was successfully conducted from March to April 2019. Only one drop-cam video was collected around Aldabra at 300m before it got lost. The drop-cam was baited and provided the most comparable methodology to the previously collected BRUVs. Nevertheless, eight underwater video transects were conducted at Aldabra (two sites surveyed at 30m, 60m, 120m and 250m each) and can provide general information on the marine predator community (but not comparable to the BRUVs data due to the different methodology).
- The data collected through the stereo-video surveys by the Nekton team is aimed at assessing benthic communities and is not comparable to BRUV methods. Analysis was done instead using only the SIF 2017 – 2019 BRUV data (up to 50m depth) and the results are being written up in a scientific report. The SIF BRUV data only goes down to 50m so it will not be possible to identify the broader depth range of the commonly occurring predators around Aldabra with only this data.
Four Aldabra staff participated in the BRUV survey and received on-the-job training on how to conduct BRUV surveys.
Jennifer received training on board the expedition on the collection of various types of data such as sea water chemistry and water currents, seabed mapping, benthic biology, specimen collection and pelagic biology.
- Equipment has been sourced to improve and optimise the Aldabra BRUV data collection programme and reduce delays, including three BRUV rigs, five GoPro cameras, camera accessories, 12 underwater loggers, three hard drives, two electronic device for data entry, etc. With the additional equipment sourced, the BRUV monitoring programme will continue and the results of this research will continue to provide valuable data to assess the long-term effectiveness of Aldabra’s zoning plan.
- Increased technical human capacity with training received by SIF staff.
- UNESCO Women in Science video
- AFOX video
- Newspaper article: 2 Seychellois women awarded fellowships to Oxford to advance study of marine science (June 3, 2019)
- SIF newsletter article:
- a) Nekton Deep Ocean Expedition on Aldabra and Sky News coverage, March 2019: http://www.sif.sc/sites/default/files/downloads/SIF%20Newsletter%20March%202019.pdf
- b) SIF staff member attends Africa Oxford Visiting Fellows Program, August 2019: http://www.sif.sc/sites/default/files/downloads/SIF%20August%20Newsletter_web.pdf
- Nekton scientific article: Woodhall et al 2019. First Descent – To explore and conserve the Indian Ocean 2019-2022. Deep Sea Life, Issue 13, 2‒4.