By Fraser Januchowski-Hartley
A school of excavating parrotfish on an East African reef
Parrotfishes are a beautiful, colourful and ubiquitous group of fishes that are present on coral reefs around the world. They’ve received a lot of attention due to their importance in both fisheries, and in how they can help to maintain coral reef health through preventing outbreaks of fleshy macroalgae, that can overgrow and out-compete corals. However, one role that parrotfish are particular important in playing on coral reefs has been somewhat overshadowed. A new study, published in Geology led by Prof Chris Perry, part of the SPACES team, has identified the pivotal role parrotfishes play to build and maintain coral reef islands.
Using survey and sedimentary data the study, coauthored by Paul Kench, Michael O’Leary, Kyle Morgan, and Fraser Januchowski-Hartley (who is also from the SPACES team), links reef ecology with sediment production and found that parrotfish produced more than 85% of the new sand-grade sediment on the reefs surrounding reef islands in the Maldives. Parrotfish have large and well-developed “beaks” that they use to scrape turf algae and benthic organisms off the surface of coral reefs. In the process they also remove some of the rock and coral substrate that underlies the algae, which is ground up while the edible content is digested, and later excreted as sand. This sand is often then transported by waves and currents to the shore, where it maintains the islands.
While this study concentrated on reef islands in the Maldives, it is highly likely that similar processes are at work along the East African coast, particularly at sites such as Vamizi Island in Mozambique, and Mombasa Marine Park in Kenya. By producing sand-grade sediment, healthy and abundant parrotfish communities can maintain beaches where tourism, recreation and cultural activities take place, providing an important and often overlooked ecosystem service.
Beach market in East Africa
The paper is ‘Linking reef ecology to island building: Parrotfish identified as major producers of island-building sediment in the Maldives’ by C.T. Perry, P.S. Kench, M.J. O’Leary, K.M. Morgan and F. Januchowski-Hartley is published in Geology.
Press release from the University of Exeter
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New publication drawing on SPACES data shows East African reefs particularly susceptible to coral bleaching
SPACES team members, Tim McClanahan and Nyawira Muthiga have used SPACES coral reef survey data in an analysis of the factors affecting coral’s susceptibility to coral bleaching in the face of warmer climates. The analysis based on surveys from E. Africa to Fiji during the 2016 El Nino event showed that bleaching is caused by […]
New Publication: Kenyan and Mozambican coral reef ‘carbonate budgets’ contribute to international picture of corals under sea-level rise.
SPACES coral reef surveys have contributed to an international picture of how reefs might be able to grow to keep up with sea-level rise, recently published in Nature. The growth of coral reefs is strongly influenced by the amount and types of coral living on the reef surface, but across both regions this growth is […]
Artisanal fisheries in Cabo Delgado, Mozambique: rural vs urban fishing centers
This working paper investigates the relationship between gear, catch and income generated by the fishers in different seasons. SPACES researchers collected data using fish catch surveys at landing sites in Pemba town, Vamizi and Lalane. A standard questionnaire was used to collect the effort and location of the fishery. The fishery shows a wide range […]
Changing dynamics of reef framework production in the Western Indian Ocean – Fraser Januchowski-Hartley et al.(1.2 MB)
Fraser Januchowski-Hartley’s presentation at the 2015 WIOMSA symposium on carbonate budget and current coral condition at SPACES sites, Mombasa, Shimoni, Vamizi, and Pemba.
Linking reef ecology to island building: Parrotfish identified as major producers of island-building sediment in the Maldives. Geology 2015
Reef islands are unique landforms composed entirely of sediment produced on the surrounding coral reefs. Despite the fundamental importance of these ecological-sedimentary links for island development and future maintenance, reef island sediment production regimes remain poorly quantified. Using census and sedimentary data from Vakkaru island (Maldives), a sand-dominated atoll interior island, we quantify the major […]
Remote coral reefs can sustain high growth potential and may match future sea-level trands. Nature Scientific Reports 2015
Climate-induced disturbances are contributing to rapid, global-scale changes in coral reef ecology. As a consequence, reef carbonate budgets are declining, threatening reef growth potential and thus capacity to track rising sea-levels. Whether disturbed reefs can recover their growth potential and how rapidly, are thus critical research questions. Here we address these questions by measuring the […]
Similar impacts of fishing and environmental stress on calcifying organisms in Indian Ocean coral reefs. Marine Ecology Press Series 2016
Calcification and reef growth processes dominated by corals and calcifying algae are threatened by climate and fishing disturbances. Twenty-seven environmental, habitat, and species interaction variables were tested for their influence on coral and calcifier cover in 201 western Indian Ocean coral reefs distributed across ~20° of latitude and longitude and up to 20 m deep. […]
Environmental variability indicates a climate-adaptive center under threat in northern Mozambique coral reefs. Ecosphere 2017
A priority for modern conservation is finding and managing regions with environmental and biodiversity portfolio characteristics that will promote adaptation and the persistence of species during times of rapid climate change. The latitudinal edges of high-diversity biomes are likely to provide a mixture of environmental gradients and biological diversity that meet the portfolio criteria needed […]
Drivers and predictions of coral reef budget trajectories. Proceedings Of The Royal Society B-biological Sciences 2017
Climate change is one of the greatest threats to the long-term maintenance of coral-dominated tropical ecosystems, and has received considerable attention over the past two decades. Coral bleaching and associated mortality events, which are predicted to become more frequent and intense, can alter the balance of different elements that are responsible for coral reef growth […]
Ecological Underwater Surveys
All information including publications, conference presentations and news items related to underwater ecological surveys is tagged below.
New paper from SPACES team members shows the positive correlation between the orange-lined triggerfish and calcifier cover
SPACES Co-investigators, Tim McClanahan and Nyawira Muthiga, have recently published the paper, Similar impacts of fishing and environmental stress on calcifying organisms in Indian Ocean coral reefs (Open Access– free to read) in the Marine Ecology Progress Series. They investigated coral and calcifier cover in 201 western Indian Ocean reefs. McClanahan and Muthiga found that coral and calcifier cover […]
Aligning Global Indicators for Coral Reef Fisheries Monitoring in the Western Indian Ocean Workshop
Recently, a member of the SPACES team attended a regional workshop in Nosy Be, Madagascar from 27 to 28 April, 2015. The workshop was convened by the Wildlife Conservation Society (WCS) and Dr Emily Darling with the aim to bring together various researchers working on coral reef fisheries in the Western Indian Ocean (WIO). The workshop […]