Kasper Elgetti Brodersen
Title: Analysing the below-ground microenvironment of seagrasses
Supervisors: Professor Peter Ralph and Professor Michael Kuhl, co-supervisors: Dr Daniel Nielsen, Dr Ole Pedersen and Dr Jens Borum
PhD conferred: 2016
Seagrass meadows are among the most productive ecosystems on earth providing a range of key ecological services such as enhancing marine biodiversity by providing feeding grounds and nursery areas for many important species e.g. green sea turtle, dugongs, juvenile fish and crustaceans. The seagrass ecosystem also plays a number of important eco-engineering roles in shallow coastal waters by providing wave protection, reducing coastal erosion, facilitating nutrient cycling, increasing sediment stabilisation, as well as carbon sequestration. Despite being a high-value ecosystem (i.e. 2-4 times higher ecosystem service value compared to mangroves and coral reefs) supporting the commercial fishing industry, as well as the marine biodiversity, seagrass meadows are currently facing a global decline mainly caused by human activity.
Seagrass is constantly challenged to support below-ground tissue with O2 owing to slow diffusion rates and low solubility of O2 in water, as well as the high O2 demand of the surrounding reduced, anoxic sediment. Inadequate internal aeration from the above-ground tissue to the below-ground tissue via the aerenchyma (gas-filled channels) can result in sulphide intrusion, which in turn can kill the plant. By using advanced microsensor and planar optode technology we will examine how changing environmental conditions (such as light intensity, flow rate, temperature) affect the health of seagrasses. Microscale studies can determine microgradients of chemical species, such as H2S, O2 and pH, around the below-ground tissue of seagrasses and observe changes in the chemical microenvironment, and thereby the biogeochemical processes, under changing environmental conditions.
The aim of this PhD project is to elucidate how changing environmental conditions affect the health of seagrasses through its effect on the chemical microenvironment around the below-ground tissue. The results of this research will help to improve our knowledge of why seagrass meadows are decreasing globally and how to better direct management resources.
During his PhD Kasper has been awarded research grants from the following Danish foundations: Augustinus Foundation (opens external site), the Fabrikant P. A. Fiskers Fond (opens an external site) and the Jorck and Hustrus Fund (opens an external site)
Elgetti Brodersen K, Lichtenberg M, Ralph PJ, Kuhl M and Wangpraseurt D (2014) Radiative energy budget reveals high photosynthetic efficiency in symbiont-bearing corals (Journal of the Royal Society Interface, vol. 11, p. 20130997)
Elgetti Brodersen K, Nielsen DA, Ralph PJ, Kuhl M. Oxic microshield and local pH enhancement protects Zostera muelleri from sediment-derived hydrogen sulphide (in review).
Elgetti Brodersen K, Nielsen DA, Ralph PJ, Kuhl M. A split flow-chamber with artificial sediment to examine the below-ground microenvironment of aquatic macrophytes ( New Phytologist DOI: 10.1111/nph.13124)
Oral presentation at a Masterclass entitled “Ecophysiology of Submerged Plants”; Nov. 2013; The University of Western Australia; School of Plant Biology; Perth, WA, Australia.
“Scientists shine a light on coral photosynthesis”.
“Casting new light on how to protect coral”. In Brink (paper version), May 2014, page 2. Web archive: newsroom.uts.edu.au/brink/archives