In the past, Maunalua Bay has supported large meadows of the native seagrass Halophila hawaiiana, as well as corals and a wide range of different organisms that rely on these complex habitats.
|
Maunalua Bay has historically supported a very diverse community.
Pictured in the center is the seagrass Halophila hawaiiana.
However, due to urbanization, the bay has become increasingly degraded. During the New Years Eve Flood of 1987, the bay was inundated with muddy sediment that buried near-shore corals, reduced seagrass cover, and provided an ideal habitat for the quick colonization of the invasive green alga Avrainvillea amadelpha, or leather mudweed. Once it entered the inshore areas of the bay, leather mudweed trapped and held the mud by covering the sand in thick mats, thereby smothering and causing the decline of seagrass meadows throughout the bay.
Leather mudweed (Avrainvillea amadelpha) trapping mud in the bay , creating an inhospitable place for seagrass.
From March 2010 to February 2011, twenty-three acres of Avrainvillea amadelpha have been removed from the inshore areas of Maunalua Bay and it appears that the trapped mud is being flushed from the bay. As a result of these removal efforts, suitable sandy areas that once supported the seagrass Halophila hawaiiana have been uncovered.
A big problem, however, is that H. hawaiiana may be extremely slow to recolonize the cleared areas of the bay on its own due to its limited dispersal capabilities. Instead of producing seeds, the seagrass mainly reproduces slowly via vegetative growth, or branching from the stem.
H. hawaiiana produces female and male flowers (pictured here) on separate plants. Even if male and female plants are near each other, they may not be flowering at the same time, thereby preventing pollination and the production of seeds.
Active restoration through the transplantation of H. hawaiiana could potentially accelerate the recovery of seagrass in Maunalua Bay. In order to reintroduce seagrass communities to cleared areas of the bay, it will be important to know the most effective techniques for transplanting Hawaii’s native seagrass. While transplantation methods have been developed for other seagrass species, very little such information is currently available for H. hawaiiana.
To determine the best method for restoration, I will test different techniques for actively restoring H. hawaiiana and evaluate the survival and growth rates of the transplanted seagrass using these different techniques.
Setting up equipment to protect transplanted seagrass |
|
|
