Competition on coral reefs between Sponges and Coral

As part of Blue Corner’s research scholarship program for Indonesian university students, each year some early career marine biologists are invited to join us for 2-4 months collecting data for a research project of their choice. Students are based at the Blue Corner Marine Research facilities in Nusa Lembongan island during their internship.

Chusnul is a marine sciences student at Padjadjaran University and worked with Blue Corner marine biologists on a study comparing rates of sponge growth and coral mortality at our coral restoration site in Nusa Penida.

Check out the Abstract from her research paper:

Competition for substrates between sponge species, notably Chalinula nematifera, and coral reefs has emerged as a significant concern in marine ecosystem dynamics.

Substrates play a pivotal role in supporting the growth and survival of diverse marine organisms. This competition extends beyond natural reef ecosystems to include artificial or human-made reef structures, increasingly employed in coral reef restoration efforts worldwide. This research, conducted in the northern part of Nusa Penida, specifically at the Blue Corner coral reef restoration frames, investigates the substrate competition dynamics between Chalinula nematifera and coral reefs in both natural and artificial ecosystems. By analyzing growth rates and mortality of coral, this study aims to comprehensively understand the competitive relationship and its implications for the health and sustainability of coral reef ecosystems. Results indicate Chalinula nematifera's distribution in the restoration area, particularly flourishing in restorations planted between 2020 and 2022. The sponge exhibits invasive behavior, growing excessively on various substrates, including live and dead coral. The correlation between sponge distribution and coral mortality suggests that C. nematifera prefers dead substrates and subsequently spreads to live coral reefs. Temperature plays a crucial role, with rising temperatures leading to coral tissue mortality, coral diseases, and coral bleaching, shifting coral reefs towards dominance by sponges. The study underscores the need for monitoring actions to comprehend the dynamics of growth, recruitment, and distribution in Indonesia's coral reef ecosystem. In conclusion, coral reef restoration faces challenges posed by invasive sponges like Chalinula nematifera, which can thrive on restoration frames. The study emphasizes the importance of long-term monitoring and growth rate studies to assess the potential threat this species poses to marine ecosystems amidst ongoing climate change.

Butterflyfish as indicators of ecological function for coral restoration monitoring

Lydia conducted a research internship with us as part of her MSc from University of Edinburgh in 2019. As one of our earlier research students working on the coral restoration site we were interested in metrics which could be used for monitoring. Together with our Blue Corner Marine Research team she developed a study to measure if corallivorous butterflyfish could be used to indicate whether or not a reef site is successfully restored.

Coral reef ecosystems have been valued as one of the most economically important ecosystems in the world, providing sources of protein, supporting and protecting urban development, and comprising the basis of many cultures and recreational activities. Despite its importance and value, reefs all over the world are being degraded and damaged due to anthropogenic factors. With the aim of protecting the reefs and re-establishing self-sustaining, functional reef systems, many marine protected areas have been established and coral reef restoration projects have been developed, particularly in the Coral Triangle area where biodiversity is the highest. 

Check out the research abstract below:
This study aimed to provide an assessment of Blue Corner’s coral restoration project in the Nusa Penida Marine Protected Area in Indonesia by examining the ecological benefits and resilience of the restored structures through comparative analysis of butterflyfish (Chaetodon) and herbivorous surgeonfish (Acanthuridae) and parrot fish (Scaridae) diversity.

Underwater video surveys were collected from three different benthic areas on the North coast of Nusa Penida: 1) restored coral structures, 2) coral rubbles, and 3) natural reefs.

Analysis of video surveys demonstrated that the both diversity of butterflyfish and herbivorous fish were higher on the restored coral structures compared to coral rubbles area. Species composition were also documented and showed a higher species similarity between the restored structures and natural reefs than between coral rubbles and natural reefs.

The results of this study indicate that the ecological functions of the coral restoration structures are being re-established as the relative health of the corals and the resilience of the reef have been improved. The findings in this study provide a basis for future monitoring projects and holds important implications for the management decisions regarding coral restoration projects.