Benthic Community Response to Marine Heatwaves Across Depth in Chagos Archipelago

This dataset assesses changes in coral reef benthic communities following successive marine heatwaves from 2015 to 2017 across a 5–25 m depth gradient in the remote Chagos Archipelago. Data were collected via repeat video surveys at 16 sites across four atolls before (2013/2014) and after (2018/2019) the heatwave events. It documents declines in hard and soft coral cover and increases in crustose coralline algae, sponge, and reef pavement.

Use Cases

• Model the relationship between initial thermal stress (measured in °C-weeks) and the loss of hard coral cover across different depth zones.
• Analyze the association between repeated thermal stress events and the loss of soft coral cover at shallow (5–15 m) versus deep (15–25 m) zones.
• Compare changes in benthic group cover (e.g., crustose coralline algae, sponge, reef pavement) before and after marine heatwaves across the four surveyed atolls.
• Investigate depth-dependent variation in community response by analyzing data from the four specific depth zones: 5–10 m, 10–15 m, 15–20 m, and 20–25 m.

Strengths

• Data collection spans a 5–25 m depth gradient, enabling analysis of depth-dependent ecological responses.
• Repeat sampling provides temporal coverage before (2013/2014) and after (2018/2019) successive marine heatwaves in 2015–2017.
• Surveys were conducted at 16 sites across four atolls (Peros Banhos, Salomon, Great Chagos Bank, Egmont) in the remote Chagos Archipelago.
• Thermal stress is quantified with specific metrics, including peak heatwave intensities of 4.2–6.1 °C-weeks in 2015 and 12.1–15.8 °C-weeks in 2016.

Limitations

• The dataset is limited to a single, remote archipelago, which may not be representative of coral reef responses in other oceanic regions.
• Sample size specifics (e.g., number of transects or data points per site/depth) are not provided in the input description.
• The temporal scope is focused on a specific pre- and post-heatwave period, lacking continuous long-term monitoring data.

Provenance

Source

Coral Reef Resilience and Recovery in the Chagos Archipelago project, authored by Sannassy Pilly, Sivajyodee.

Collection Method

Benthic community assessment via 10-minute continuous video swims at a constant speed, with scaled measurement using laser pointers.

Time Range

Primary surveys conducted in March–April 2013/2014 (before) and 2018/2019 (after) the 2015–2017 marine heatwaves.

Freshness

Data last updated on 2026-01-15, though the core observational period ended in 2019.

Geography

Chagos Archipelago, Central Indian Ocean, covering 16 forereef slope sites across four atolls: Peros Banhos, Salomon, Great Chagos Bank, and Egmont.