Socio-ecological drivers of fish biomass on coral reefs: the importance of accessibility, protection and key species

Maire, Eva (2019) Socio-ecological drivers of fish biomass on coral reefs: the importance of accessibility, protection and key species. PhD thesis, James Cook University.

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Abstract

Coral reefs have the greatest biodiversity of any ecosystem on the planet and support ecosystem goods and services to million people who depend directly on them for food, economic income, coastal protection and cultural values. There is a clear consensus that accessibility through road networks and infrastructure expansion is a main driver of ecosystem conditions, with the most accessible resources being most at risk. Yet to date measuring the extent to which coral reefs are accessible to humans is strictly limited to examining the linear distance between fishing grounds and markets or ports. However, linear distance ignores ragged coastlines, road networks and other features that can affect the time required to reach fishing grounds from a human settlement. This thesis presents a double challenge: (i) developing new metrics of accessibility that account for seascape heterogeneity to better assess human impacts on coral reefs; and (ii) evaluating the importance of coral reef accessibility, in interactions with their management, to explain variations of fish biomass. First, I estimated the travel time between any given coral reef and human populations and markets based on the friction distance which is related to transport surfaces (paved road, dirt road, water) influencing transportation costs and the effective reach from human settlements. I found that travel time is a strong predictor of fish biomass. Second, using a downscaling of the travel time approach I illustrated how market proximity can affect the behavior of fishermen and, ultimately, trigger changes in marine resource exploitation in North-Western Madagascar. Market access appears as a critical step toward a long-term management of coral reef fisheries. Third, travel time was used to build a human gravity index, defined as human population divided by the squared travel time, to better assess the level of human pressure on any reef of the world. Then, gravity was used to assess the effectiveness of marine reserves given the level of human pressure. The results highlighted critical ecological trade-offs in conservation since reserves with moderate-to-high human impacts provide substantial gains for fish biomass while only reserves located where human impacts are low can support populations of top predators like sharks which are otherwise absent from coral reefs. Fourth, I developed a new Community-Wide Scan (CWS) approach to identify fish species that significantly contribute, beyond the socio-environmental and species richness effects, to fish biomass and coral cover on Indo-Pacific reefs. Among about 400 fishes, I identified only a limited set of species (51), belonging to various functional groups and evolutionary lineages, which promote biomass and coral cover; such key species making tractable conservation targets. Within the context of global changes and biodiversity loss, the thesis challenges the sustainable and efficient management of coral reef socio-ecological systems with accessibility being the cornerstone but also the main danger in a near future where roads will expand and coastal human populations will grow.

Item ID: 60625
Item Type: Thesis (PhD)
Keywords: fish community, fish biomass, ecosystem functioning, ecosystem services, human pressure, accessibility, gravity, Marine Protected Areas, coral reefs, socio-ecological systems, conservation
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Copyright Information: Copyright © 2019 Eva Maire.
Additional Information:

Four publications arising from this thesis are stored in ResearchOnline@JCU, please see the Related URLs field. The publications are:

Chapter 2: Maire, Eva, Cinner, Joshua, Velez, Laure, Huchery, Cindy, Mora, Camilo, Dagata, Stephanie, Vigliola, Laurent, Wantiez, Laurent, Kulbicki, Michel, and Mouillot, David (2016) How accessible are coral reefs to people? A global assessment based on travel time. Ecology Letters, 19 (4). pp. 351-360.

Chapter 4: Cinner, Joshua E., Huchery, Cindy, MacNeil, M. Aaron, Graham, Nicholas A.J., McClanahan, Tim R., Maina, Joseph, Maire, Eva, Kittinger, John N., Hicks, Christina C., Mora, Camilo, Allison, Edward H., D'Agata, Stephanie, Hoey, Andrew, Feary, David A., Crowder, Larry, Williams, Ivor D., Kulbicki, Michel, Vigliola, Laurent, Wantiez, Laurent, Edgar, Graham, Stuart-Smith, Rick D., Sandin, Stuart A., Green, Alison L., Hardt, Marah J., Beger, Maria, Friedlander, Alan, Campbell, Stuart J., Holmes, Katherine E., Wilson, Shaun, Brokovich, Eran, Brooks, Andrew J., Cruz-Motta, Juan J., Booth, David J., Chabanet, Pascale, Gough, Charlie, Tupper, Mark, Ferse, Sebastian C.A., Sumaila, U. Rashid, and Mouillot, David (2016) Bright spots among the world's coral reefs. Nature, 535 (7612). pp. 416-419.

Chapter 4: Cinner, Joshua E., Maire, Eva, Huchery, Cindy, MacNeil, M. Aaron, Graham, Nicholas A.J., Mora, Camilo, McClanahan, Tim R., Barnes, Michele, Kittinger, John N., Hicks, Christina C., D'Agata, Stephanie, Hoey, Andrew S., Gurney, Georgina G., Feary, David A., Williams, Ivor D., Kulbicki, Michel, Vigliola, Laurent, Wantiez, Laurent, Edgar, Graham J., Stuart-Smith, Rick D., Sandin, Stuart A., Green, Alison, Hardt, Marah J., Beger, Maria, Friedlander, Alan M., Wilson, Shaun, Brokovich, Eran, Brooks, Andrew J., Cruz-Motta, Juan J., Booth, David J., Chabanet, Pascal, Gough, Charlotte, Tupper, Mark, Ferse, Sebastian C.A., Sumaila, U. Rashid, Pardede, Shinta, and Mouillot, David (2018) Gravity of human impacts mediates coral reef conservation gains. Proceedings of the National Academy of Sciences of the United States of America, 115 (27). E6116-E6125.

Chapter 5: Maire, Eva, Villéger, Sébastien, Graham, Nicholas A.J., Hoey, Andrew S., Cinner, Joshua, Ferse, Sebastian C.A., Aliaume, Catherine, Booth, David J., Feary, David A., Kulbicki, Michel, Sandin, Stuart A., Vigliola, Laurent, and Mouillot, David (2018) Community-wide scan identifies fish species associated with coral reef services across the Indo-Pacific. Proceedings of the Royal Society of London Series B, Biological Sciences, 285 (1883). 20181167.

Date Deposited: 16 Oct 2019 05:32
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 33%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 33%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 34%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 33%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 33%
97 EXPANDING KNOWLEDGE > 970105 Expanding Knowledge in the Environmental Sciences @ 34%
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