How do Moreton Bay Seagrass cope with reduced light?
The availability of light is one of the critical factors that affects seagrass survival. It is also light availability that dictates the depth to which seagrass may grow. It is has been shown that generally species within the genus Halophila are those that can survive in both deeper and more turbid waters. 1.
In coastal waters and estuaries, seagrass meadows are often subject to light deprivation over short time scales (days to weeks) in response to increased turbidity from human disturbances. Seagrass may exhibit negative physiological responses to light deprivation and suffer stress, or tolerate such stresses through photo-adaptation of physiological processes allowing more efficient use of low light. 2.
Recent research (2009) results suggested that Halophila ovalis (a seagrass dugong rely upon for food) is more vulnerable to light deprivation than Zostera capricorni. While H. ovalis, at depths of 5-10 m, would be more vulnerable to light deprivation than intertidal populations. Both species showed a strong degree of photo-adaptation to light manipulation that may enable them to tolerate and adapt to short-term reductions in light. 2.
Zostera muelleri ssp. capricorni is the most common of all the seagrass species found in Moreton Bay while H.ovalis is also prevalent.
As we review the recent Moreton Bay Seagrass Watch data we will begin to understand how the 2011 floods have affected seagrass and how resilient they maybe.
References:
1. Chp 8. Vulnerability of seagrasses in the Great Barrier Reef to Climate Change
2. Chlorophyll fluorescence measures of seagrasses Halophila ovalis and Zostera capricorni reveal differences in response to experimental shading.
