Protect Maui's Manta Rays
The Hawaii Association for Marine Education and Research (HAMER) is a not for profit organization dedicated to understanding and protecting Hawaii's marine environment. Our dedicated HAMER team have been studying the manta rays at Olowalu Reef on Maui for the past decade. In recent years, manta sightings have dropped dramatically and the coral reef habitat they come to visit is under serious threat of land-based sources of sediment and pollution. We are asking for your support to help us protect and restore the Olowalu Reef to ensure our iconic manta population is healthy and thriving as well as the fish and corals they depend on for survival. Our primary goals for 2017 will be to focus on stopping the destructive seawall planned for the southshore of Olowalu, continue monitoring water quality to identify and stop the greatest threats of land-based sediments and sustain our manta ray monitoring research. Please, we need your support more than ever!
Your donation is tax deductible.
WHAT IS SEDIMENT AND WHY IS IT BAD?
Land-based sediment comes from humans altering the natural landscape through seawalls, urban development, agriculture, and the introduction of invasive species such as pigs and deer. These activities cause loose dirt (sediment) to be exposed and gets picked up by rain water as it moves downhill creating "brownwater". The sediment is often tainted with pollutants such as pesticides, herbicides and petroleum products. The brownwater eventually ends up in the ocean, blanketing and killing our coral reefs. Over time the sediment eventually settles on the bottom, only to be resuspended with each new wave event. Additionally, new coral larvae (the next generation of corals) need a hard bottom to settle onto and grow. Many of our coral reefs don't have new corals growing because most of the entire bottom is covered in loose sediment.
HOW DOES SEDIMENT AFFECT THE MANTAS?
Manta rays rely on coral reefs for two primary reasons. First, their primary food source is plankton, all the microscopic larvae released from coral, invertebrates, and fish during spawning events. Second, mantas get covered by thousands of parasites and they visit the coral reefs to have the parasites removed by cleaner wrasses and other fish species by visiting "cleaning stations", such as what we find at Olowalu. As coral reefs die from sediment impacts, the food source and cleaning stations that mantas rely on for survival also disappear.
HOW DO WE PROPOSE TO FIX THE PROBLEM?
There are many simple and cost-effective ways to prevent sediment and the pollutants they carry, from being carried downhill and ending up in the ocean. This requires: 1) identifying the sources of the most problematic sediment contributers, 2) educating land-owners on how they can retain the sediment on their property and 3) enforce our environmental laws, such as the Clean Water Act, to hold land-owners, who don't feel the need to comply with the laws, accountable for their actions.
The team at HAMER is using automated multi-parameter water quality probes to understand where the most problematic areas occur. These probes can be automated to collect data continuously and transmit the data to any smartphone at any time. This removes the need for agency regulators to have to go to a problematic area and collect a sample for analysis, which usually can't occur during a storm event. This removes the need for increased budget and staffing to address Maui's 85% public waters being below water quality standards. But implementing this new technology has been a challenge because it creates accountability but we are making progress in demonstrating the effectiveness of the equipment.
Our team is also working closely with the Department of Transportation and other stakeholders to eliminate seawalls along our coastline, that destroy our beaches and contribute to our sediment problem, and to continue to work towards temporary and permanent solutions to protecting our West Maui highway that preserves the coastline while keeping motorists safe from rising sea levels that are undermining the road. We are working hard to see that the Pali to Puamana Parkway Plan (8 miles of coastline with open space and park available to the public) becomes as reality so that everyone on Maui has easy access to beaches, surfing, fishing, snorkling and camping in perpetuity.
HOW DO WE MONITOR THE MANTA RAYS?
We use several techniques for studying the manta rays. By photographing the unique spot patterns on their belly we not only determine how many individuals we have in our population but we continue to keep track of individuals that are re-sighted over time, providing valuable information such as pregnancy rates and social behavior. We also use paired-laser photogrammetry to measure their size and keep track of growth rates and make comparisons with other populations around the world. We are using small skin samples to examine how much mixing occurs between island populations, an important component to know to determine is we need to manage the populations separately or as a whole. The genetics work will also tell us which mom and dads in the population are having the most offspring on how everyone is related. And lastly we are putting satellite tags on certain individuals that are helping us uderstand where these animals spend most of their time spatially, in 3-dimensions and well as temporally (night versus daytime). A tag we recently put on a young manta provided the first information ever on where the mysterious pupping grounds may be.
After over 600 hours of surveying and hundreds of hours of photo-id matching by our wonderfully dedicated volunteers and interns, we can now compare how manta ray sighting rates on Maui have changed over the past decade. The trend is alarming. In 2008, you were 13 times more likely to see manta rays than in 2016 and in just the past year alone, sighting rates have dropped by two thirds. The exact reasons for this is not clear but we believe that the deteriorating Olowalu Reef from the onslaught of land-based sediment and pollutants is playing a major role hence why HAMER's #1 priority in 2017 is to take on the sediment issue.