Project Title: Environmental tolerances and drivers of deepwater seagrass photophysiology
Supervisors: Prof. Peter Ralph, Prof Tony Larkum and Dr Michael Rasheed (JCU).
While research has focused on shallow water coastal seagrasses over the last 20 years, little is known of the ecological role, tolerances and drivers of their deepwater (>10) counterparts. Within the Great Barrier Reef World Heritage Area, deepwater seagrasses are estimated to occupy more than 35,000 km2 of the reef lagoon. These deepwater meadows are often within the footprint of port and shipping activity where dredging, associated plumes and ship movements create chronic threats to their long term survival.
In marine environments, light is attenuated by water depth, and the spectrum of available light shifts from full sunlight to shorter wavelengths as one moves deeper in the water column. Seagrasses, which grow across this light gradient, are challenged by a dynamic shift in both the light quantity and quality. Little work has been done on how deepwater seagrasses acclimate to this limited light environment which impinges upon their growth and capacity to support primary production. The spectral signature of light at depth may have a profound effect on how photosynthetic machinery has adapted to maintain efficiency while harnessing a narrowed spectrum.
This research will determine the drivers of seasonal and inter-annual change in deepwater tropical seagrasses. It will focus specifically on Halophila spp. to determine how deficiencies in light intensity and specific wavelengths may affect their physiological characteristics. Studies will assess how the ambient light environment affects plant physiology and how natural seasonal changes like the onset of wet season flooding may alter the light-growth relationship.This research will further identify key environmental cues which will hopefully feed into local management strategies for mitigating coastal developmental impacts, most notable port developments and dredging, along the Great Barrier Reef.
Katie has been awarded a 5 year grant from Queensland Gas Corporation Pty Ltd to support her research.
Macreadie PI, Schliep M T, Rasheed MA, Chartrand KM, & Ralph PJ (2014) Molecular indicators of chronic seagrass stress: A new era in the management of seagrass ecosystems?. Ecological Indicators, 38. pp. 279-281
Petrou K, Jimenez-Denness I, Chartrand KM, Bryant CV, Rasheed MA and Ralph PJ (2013) Seasonal heterogeneity in the photophysiological response to air exposure in two tropical intertidal seagrass species. Marine Ecology Progress Series, 482. pp. 93-106
Grech AM, Chartrand KM, Erftemeijer PLA, Fonseca MS, McKenzie L, Rasheed MA, Taylor H and Coles RG (2012) A comparison of threats, vulnerabilities and management approaches in global seagrass bioregions. Environmental Research Letters, 7 (2). pp. 1-8
Chartrand K, Rasheed M, Petrou K, & Ralph P J (2012) Establishing tropical seagrass light requirements in a dynamic port environment. In Proceedings of the 12th International Coral Reef Symposium, Seagrasses and seagrass ecosystems, Cairns, Australia.
Unsworth RK, Rasheed MA, Chartrand KM, & Roelofs A J (2012) Solar radiation and tidal exposure as environmental drivers of Enhalus acoroides dominated seagrass meadows. PloS one, 7(3), e34133
Chartrand KM, Durako MJ and Blum JE (2009) Effect of hyposalinity on the photophysiology of Siderastrea radians. Marine Biology, 156. pp. 1691-1702
Chartrand KM and Durako MJ. (2009) Distribution and Photobiology of Siderastrea Radians and Thalassia Testudinum in Florida Bay, Florida, USA. Bulletin of Marine Science 84(2). pp. 153-166
Durako MJ and Chartrand KM (2008) Changes in spectral reflectance in response to salinity variation in Siderastrea radians from Florida Bay, Florida USA. Proceedings of the 11th international coral reef symposium, Ft. Lauderdale, FL.
George AL, Caldieraro JB, Chartrand KM, & Mayden RL (2008) Population genetics of the blue shiner, Cyprinella caerulea. Southeastern Naturalist. 7(4). pp. 637-650