Climate change alterations to ecosystem dominance: how might sponge-dominated reefs function?

Area of Science:

• Marine Ecology
• Ecological Modeling
• Conservation Biology

Background:

• Coral reefs face global and local anthropogenic stressors, leading to rapid ecological changes.
• Future coral reef ecosystems are predicted to function differently from current coral-dominated states.
• Understanding shifts in dominance, particularly by sponges, is crucial for predicting ecosystem services.

Purpose of the Study:

• To explore the ecological impacts of changing sponge dominance on coral reef ecosystems.
• To model potential future reef states under varying degrees of sponge dominance.
• To identify critical knowledge gaps for predicting the function of sponge-dominated reefs.

Main Methods:

• Qualitative modeling was used to simulate future reef trajectories.
• The study explored outcomes based on increased sponge abundance versus declining coral abundance.
• Uncertainty analysis was employed to highlight key research needs.

Main Results:

• Qualitative modeling indicated that the drivers of increased sponge dominance (higher abundance vs. coral decline) yield different outcomes for other trophic levels.
• The study identified specific areas of uncertainty requiring further investigation.
• The findings suggest a potential shift in reef ecosystem function.

Conclusions:

• Addressing knowledge gaps in sponge ecology and their interactions with other benthic organisms is essential.
• Quantifying carbon flow, food limitation, the 'sponge loop,' and competitive interactions are critical.
• Developing more complex models is necessary to accurately assess the functional attributes of future sponge-dominated reef ecosystems.