Long Term Records to Strengthen Our Understanding of Coral Resilience
Coral reefs are the largest mass of construction workers on the face of the earth. They are natural architects in the shallow sea but only remain productive when juvenile corals are able to survive after recruitment onto the reef. At every dive location on the reef around Little Cayman, we see evidence of recruitment. This is a good sign for the future.
Using the AGRRA, Atlantic Gulf Rapid Reef Assessment protocol and collecting additional recruitment data, this project investigates the potential for juvenile corals to survive and replenish the local reefs. Results from this work will help generate an understanding of the mechanisms that are driving reef resilience.
AGRRA data on the benthic habitat and fish populations surrounding Little Cayman has been collected regularly since 1999. As CCMI researchers continue to collect this data annually, notes, reports, and peer reviewed journal articles are available online to scientists, policy-makers, and the general public. These surveys document patterns of local change over the last two decades and enable regional comparisons through the Healthy Reef Framework developed for evaluating the Mesoamerican Barrier Reef.
Key Results from the latest Little Cayman Reef Report Card (released 2022):
- Of the reefs surveyed, 10% were in “very good” health in 2021, 40% were “good +”, and 40% were “good”.
- At the bottom end of the health spectrum, we had no surveyed reefs listed as in “poor” health and only 10% classed as “fair”.
- Composition of the coral community on the reef has shifted over time, from reefs dominated by massive boulder corals, such as Orbicella spp., to smaller corals such as Agaricia spp. and Porites spp.
- The size of corals surveyed has decreased by 60% overall, which may indicate that the reefs are less structurally robust and capable of providing some of the important services we depend upon them for, such as storm protection and complex habitats for a variety of marine life.
- There was a decline of 13% in the cover of algae on the reefs in Little Cayman from 1999 to 2021.
- New coral recruits, or baby corals, have declined by 83% from 2006 to 2021. Within that, researchers also see that of the species of recruits recorded, there are almost no Orbicella spp recruits and no Montastrea spp recruits after 2017, both of which are important boulder corals.
- Fish abundance (density), biomass and species richness have all increased overall since 1999, indicating a rebounding fish population.
- Fish biomass has been higher inside of Marine Protected Areas (MPAs) compared to outside throughout the 23 years of surveys; in 2021, this was 40% higher inside MPAs than outside.
- Parrotfish density has increased by 47% since 1999.
- Grouper density has rebounded following protections enacted in 2016.
- Shifts in species contributions, colony size and recruitment indicate that while coral cover remains high, coral populations are vulnerable.
- Local protections and low human impact have undoubtedly shielded Little Cayman from the extremity of global pressures that are heavily impacting reefs around the globe; however, changes are still occurring that put the reefs increasingly at risk.
View the reports by release year below.
2015 – Project Overview