A newly published Scientific Reports paper, part of the Nature Portfolio, led by Dr. Calum J.G. Murie provides new insight into how reef ecosystems influence shark and ray communities in southern Mozambique.
Titled “Fish and coral communities shape elasmobranch reef use in southern Mozambique” (DOI: https://doi.org/10.1038/s41598-025-32333-y), the study is co-authored by Mario Lebrato, Livia Gavard, and Simon P. Oliver, with contributions from BCSS and Underwater Africa.
This peer-reviewed study explores how coral structure and reef fish communities are associated with where reef-associated sharks and rays are observed, contributing to a growing body of work in Western Indian Ocean marine science.
What Was the Study Asking?
Sharks and rays (collectively known as elasmobranchs) are often used as indicators of reef health. But an important ecological question remains:
Do the biological characteristics of reefs — such as coral cover and fish community composition — influence how sharks and rays use those reefs?
Rather than assuming predators distribute themselves randomly across habitats, this research asked whether differences in reef structure and prey communities shape elasmobranch distribution patterns.
This is a critical question for regional marine science, where reef systems support both biodiversity and coastal economies.
How Was the Research Conducted?
The team conducted monthly surveys over a one-year period at four reef sites in southern Mozambique.
Methods included:
- Underwater video surveys to record shark and ray presence
- Coral community assessments
- Reef fish surveys
- Quantitative ecological analysis
By pairing predator observations with detailed measurements of coral cover and fish assemblages, researchers were able to test whether reef structure and fish communities influenced elasmobranch occurrence.
This integrated ecological approach reflects the strength of BCSS ocean observatory research: multi-ecosystem, time-series monitoring rather than isolated sampling events.
This map shows the four reef sites surveyed along the southern Mozambique coastline.
What Did the Study Find?
The results provide evidence of consistent ecological patterns linking reef structure, fish communities, and elasmobranch observations.
1. Reef Composition Matters
Reefs with different coral cover and structural characteristics supported different shark and ray communities.
This suggests that predator presence is influenced by specific habitat characteristics, rather than occurring uniformly across reef environments.
2. Fish Communities Influence Predator Presence
The composition of reef fish assemblages was linked to differences in elasmobranch observations.
Where prey communities differed, predator communities differed too.
These findings are consistent with established ecological understanding that predator distributions are linked to lower trophic levels.
3. Habitat Complexity Supports Ecological Function
Sites with greater structural complexity showed distinct ecological patterns.
Structural complexity — often driven by coral diversity and reef condition — can influence:
- Foraging opportunities
- Predator refuge
- Movement patterns
In practical terms, degraded reefs may not just lose coral — they may also lose their ecological capacity to support higher trophic species.
4. Predator Presence Reflects Ecosystem Structure
Rather than treating sharks and rays as isolated conservation targets, the study demonstrates that their presence reflects underlying ecosystem dynamics.
Protecting elasmobranchs therefore requires protecting coral systems and fish communities simultaneously.
These results show how species and reef characteristics differ across sites.
Why This Matters for Ecosystem Resilience and Climate Context
The Western Indian Ocean is one of the most climate-vulnerable marine regions globally.
Rising sea temperatures, coral bleaching events, and shifting oceanographic patterns threaten reef integrity.
The study highlights important ecological relationships that are relevant to understanding how reef systems function under changing environmental conditions.
In particular, it shows that:
- Changes in coral structure may influence broader ecosystem dynamics
- Variability in fish communities is associated with differences in predator presence
- Habitat condition plays a role in shaping reef-associated species distributions
In a changing ocean, long-term data are essential to distinguish natural variability from structural ecological shifts.
Without sustained observation, these relationships remain invisible.
This figure highlights how coral and fish communities are linked to ecosystem structure across reef sites.
The Role of the BCSS Ocean Observatory
This publication also highlights the value of long-term observational platforms such as the BCSS Ocean Observatory in the Bazaruto Archipelago.
BCSS hosts Africa’s first permanent multi-ecosystem Ocean Observatory focused on long-term time-series monitoring. By integrating coral, fish, pelagic, and environmental data streams, the Observatory enables exactly this type of ecosystem-scale analysis.
It illustrates how regionally collected field data can contribute to internationally peer-reviewed research when supported by consistent monitoring and collaboration.
Long-term datasets allow scientists to:
- Detect ecological change
- Understand predator-prey dynamics
- Inform ecosystem-based management
- Support marine spatial planning
For policymakers, ESG stakeholders, and conservationists , the message is clear: structured observation platforms are not optional — they are foundational.
From Global Publication to Regional Impact
Publication in Scientific Reports places this work within a global scientific conversation.
But its implications are deeply regional.
For Mozambique and the broader Western Indian Ocean:
- Reef protection strategies must consider ecosystem connectivity.
- Predator conservation depends on habitat conservation.
- Climate resilience planning must be data-driven.
BCSS acts as a science-policy bridge in this landscape, translating structured research into actionable knowledge for conservation authorities, blue economy stakeholders, and international collaborators.
Photo by Orlando Miranda & Salvador Colvee
Strengthening Western Indian Ocean Ocean Science
This study contributes to a growing body of Western Indian Ocean research that moves beyond descriptive biodiversity reporting and towards a more detailed understanding of ecological relationships within reef systems.
It shows that:
- Reef structure and fish communities are linked to predator observations
- Ecosystem complexity plays a role in shaping species distributions
- Long-term monitoring supports more robust ecological interpretation
For scientists and collaborators, it highlights the importance of integrated, multi-ecosystem research approaches.
For policy and conservation, it reinforces the need for sustained data collection to support informed decision-making.
Read the Full Paper
Read the full paper and discover how long-term ocean observations are shaping climate and ecosystem science in the Western Indian Ocean:
DOI: https://doi.org/10.1038/s41598-025-32333-y
Journal page: https://www.nature.com/articles/s41598-025-32333-y
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https://bcssmz.org/ocean-observatory-scientific-publications/
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For questions about this article, please contact:
Ekaterina Kalashnikova, Bazaruto Archipelago – Ocean Observatory Bazaruto Center for Scientific Studies ekaterina.kalashnikova@bcssmz.org
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