Dugong

PROJECT TITLE: Dugong population structure, connectivity and movements along the developing central Queensland coastline

RESEARCHERS: Janet Lanyon, Jennifer Seddon & Alexandra McGowan (PhD candidate)
LOCATION: Gladstone to Townsville, QLD

The expansion of six major ports has been proposed for Queensland, including Gladstone and the recently approved Abbot Point (Bowen). This region is also home to important inshore seagrass habitat for dugongs, and includes seven significant Dugong Protection Areas, many close to these expanding industrial areas. The movement of dugong populations vary from irregular large-scale relocations to small, localised movements in response to food availability or local water temperature1,2,3.

This project aims to:
• examine population genetic structure of dugongs using dugong-specific nuclear DNA markers (microsatellites) developed by the researchers, in addition to mitochondrial DNA.
• increase our understanding of dugong populations (size, structure and connectivity) in a region of current and proposed coastal development through genetic population analysis.
• determine how the dugong populations of central Queensland are related to those in southern Queensland4.

This study will allow the researchers to identify key habitats and movement pathways, estimate effective population sizes (number of breeding adults in population) and migration rates, and thus establish reliable data regarding these populations before more coastal development occurs. This information will indicate which populations are separate and which connected and will help us to predict population-level impacts, particularly across areas marked for development and expansion of ports.

DEFINITIONS:
Nuclear DNA markers (microsatellites): a set of short repeated DNA sequences at a particular location on a chromosome, which vary in number in different individuals and so can be used for genetic fingerprinting.

Mitochondrial DNA: the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, adenosine triphosphate (ATP).

REFERENCES:
1. Gales NJ, McCauley RD, Lanyon JM, Holley DK (2004) Change in abundance of dugongs in Shark Bay, Ningaloo and Exmouth Gulf, Western Australia: evidence for large scale migration. Wildl Res. 31: 283-290.
2. Lanyon J, Johns T, Sneath H (2005) Year round presence of dugongs in Pumicestone Passage, south-east Queensland, examined in relation to water temperature and seagrass distribution. Wildl Res. 32: 361-368.
3. Sheppard JK, Preen AR, Marsh H, Lawler IR, Whiting SD, Jones RE (2006) Movement heterogeneity of dugongs, Dugon dugon (Muller), over large spatial scales. J Exp Mar Biol Ecol. 334: 64–83.
4. Seddon JM, Ovenden JR, Sneath HL, Broderick D, Dudgeon CL, Lanyon JM (2014) Fine scale population structure of dugongs (Dugong dugon) implies low gene flow along the southern Queensland coastline. Biol. Conserv. 15: 1381-1392.

PROJECT: Seagrass dispersal by marine mega-herbivores Dugong dugon and Chelonia mydas

RESEARCHERS: Rob Coles, Brad Congdon, Samantha Tol, Jessie Jarvis & Paul York

LOCATION: Great Barrier Reef Marine Park and Cairns Turtle Rehabilitation Centre

Dugongs (Dugong dugon) and green turtles (Chelonia mydas) are two endangered species that rely on seagrass as a major food source. By understanding and in turn better managing seagrass habitats the researchers aim to assist in the long-term conservation of these iconic species.

Seagrasses are marine plants that create an important ecosystem, providing food for a range of species and nurseries for many commercially important fisheries. Seagrasses are also one of the most at risk ecosystems globally 1 with estimated global reductions of 29% since 1879 2 largely due to climate change and increased coastal development. Recent extreme weather events during 2010 and 2011 along the eastern Australian coast lead to a drastic reduction in seagrass meadows, with only a few effected meadows showing signs of recovery3,4,5.

Seagrass meadows can recover through sexual or asexual means including seeds dispersing small distances by ocean currents and tidal action, which occurs for the majority of seagrass species 6,7,8,9.

This project aims to understand the recovery and re-establishment capacity of seagrass meadows by:

1. Examining whether dugongs and sea turtles disperse seagrass seeds through their faecal matter and whether those seeds are viable and capable of germination
2. Determining whether these seeds have an increased, decreased or equal germination success rate compared to seeds directly released from the plant
3. Determining the abiotic dispersal capabilities of tropical seagrass by examining the passive dispersal mechanisms of seagrass fragments, their buoyancy and growth rate, and settlement success.

The results from this project will inform models explaining the probability of recovery for individual seagrass meadows, allowing for targeted management through highlighting sites that may benefit from restoration programs.

DEFINITION:

Abiotic: non-biological e.g. wind

REFERENCES

1. Orth, R., T. Carruthers, W. Dennison, C. Duarte, J. Fourqurean, K. Heck, R. Hughes, G. Kendrick, J. Kenworthy, and S. Olyarnik. 2006a. A global crisis for seagrass ecosystems. Bioscience 56:987-996.
2. Waycott, Michelle, et al. "Accelerating loss of seagrasses across the globe threatens coastal ecosystems." Proceedings of the National Academy of Sciences 106.30 (2009): 12377-12381.
3. Devlin, M., J. Brodie, A. Wenger, E. da Silva, J. Alvarez- Romero, J. Waterhouse, and L. McKenzie. 2012. Extreme weather conditions in the Great Barrier Reef: Drivers of change? Page 5. Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia.
4. McKenzie, L., C. Collier, and M. Waycott. 2012. Reef Rescue Marine Monitoring Program-Inshore Seagrass, Annual Report for the sampling period 1st July 2010–31st May 2011. Page 41. Department of Employment, Economic Development and Innovation (Fisheries Queensland), Cairns, Australia.
5. Rasheed, M., S. McKenna, A. Carter, and R. Coles. 2014. Contrasting recovery of shallow and deep water seagrass communities following climate associated losses in tropical north Queensland, Australia. Marine pollution bulletin 83:491-499.
6. Rasheed, M., S. McKenna, A. Carter, and R. Coles. 2014. Contrasting recovery of shallow and deep water seagrass communities following climate associated losses in tropical north Queensland, Australia. Marine pollution bulletin 83:491-499.
7. Nathan, R., and H. Muller-Landau. 2000. Spatial patterns of seed dispersal, their determinants and consequences for recruitment. Trends in Ecology & Evolution 15:278-285.
8. Larkum, A., R. Orth, and C. Duarte 2006. Seagrasses: Biology, Ecology and Conservation. Springer, Dordrecht, The Netherlands.
9. Orth, R., M. Harwell, and G. Inglis. 2006b. Ecology of seagrass seeds and seagrass dispersal processes. Pages 111-133. Seagrasses: Biology, ecology and conservation. Springer.