Please select your home edition
Sailing Holidays 2019 - TOP

Hope for coral reef recovery in American Samoa? Preliminary observations from the field

by Morgan Winston, NOAA Fisheries 6 Mar 13:19 UTC
NOAA divers identify and measure coral colonies along a transect in Vatia's outer bay while American Samoa Department of Land and Natural Resources and National Marine Sanctuaries divers observe the survey methods. © NOAA Fisheries / Morgan Winston

For three weeks in January, we conducted coral reef surveys in Vatia Bay and Faga'alu Bay on the island of Tutuila, American Samoa. Our small but mighty team collected data on coral condition and benthic community composition at 60 sites.

A fundamental part of our mission was to help local and federal agencies in American Samoa continue coral reef monitoring surveys in the future. We devoted several days to training our partners from the American Samoa Department of Marine & Wildlife Coral Reef Advisory Group and the National Marine Sanctuary of American Samoa in our benthic survey methods.

Now that we are back in the office on O'ahu, we're digging into the data to see if management actions to reduce land-based sources of pollution have had observable effects on the coral communities.

General trends in coral reef communities

In the inner-bay sites of both Vatia Bay and Faga'alu Bay, we observed high levels of turbidity and sedimentation stress. Visibility tended to be quite poor at our shallow and near-shore sites, where the reefs have been most affected by terrigenous runoff, sedimentation, and turbidity in the past.

The outer-bay sites had comparatively clearer water and the coral community appeared healthier and more diverse. We observed more coral species in Vatia Bay than Faga'alu Bay.

We hoped to see signs of recovery in Faga'alu Bay following the 2014 management actions to reduce nutrient and sediment runoff. In the shallow, northern forereef, we noticed evidence of improvement—the corals are growing here again! Even in the backreef of Faga'alu, there appeared to be an increase in coral cover.

We will process our data over the next few months to see if these in-water observations are reflected in our quantitative statistical results. We will also explore changes over time in benthic cover, adult and juvenile coral density, coral partial mortality, and coral biodiversity.

Coastal runoff and increased nutrient inputs appear to impact Vatia Bay as a continued result of poor nearshore land use practices and wastewater management. However, until we finish our data analysis, it is too soon to draw conclusive trends about changes in the coral communities over time.

Macroalgae and corallimorph overgrowth

In both bays, the persistence of macroalgae such as Dictyota, Valonia, Peyssonalia and Halimeda suggests nutrients are fueling their growth. Such nutrients are likely coming from land.

We also spotted the invasive corallimorph Rhodactis howesii at several of our mid-depth sites in Vatia. Rhodactis is a highly poisonous, defiant competitor for space, easily overgrowing and displacing scleractinian corals.

Under the right conditions, it can become pervasive—we have seen this in the Pacific Remote Islands Marine National Monument at Palmyra Atoll and Howland Island. Research implicates iron leachate from shipwrecks and metallic debris in promoting Rhodactis proliferation.

Resilient corals

During our first dive in the inner-bay at Vatia, where visibility was less than 15 feet, we encountered a massive Porites lobata colony. It sat approximately 13 feet wide (4 m diameter) and nearly 10 feet tall (3m height) in the middle of the murky water.

At first glance, the colony appeared mostly dead and overgrown with algae. Surprisingly, closer inspection revealed that the colony surface was carpeted with a thin layer of mucous that trapped sediment and particles.

As the mucous sheet peeled off, healthy coral tissue was revealed underneath—a remarkable adaptation that has allowed this goliath to survive years, if not decades, of sedimentation. As it turns out, more than 80 percent of this large colony surface was alive!

The ability of Porites to produce mucous sheets to shed off excess sediments in response to sediment stress has been observed before. Indeed, mucous sheet prevalence may prove to be an effective bioindicator of sediment exposure.

Our mission for building capacity and strengthening partnerships

After the three days of classroom and in-water reef sampling training, some of our partners joined us for several surveys at Faga'alu and Vatia. They will implement a variation of our method in their own coral surveys to come. We also provided them with a new geographic information systems tool to help visualize how human and environmental stressors affect nearshore reefs around Tutuila.

Continuing the conservation effort and success in American Samoa

The mitigation efforts conducted in 2014 to reduce sediment loading into Faga'alu Bay were a meaningful management action. Still, local resource management agencies, stakeholders, and community members have much work to do.

Conservation and recovery of these long-impacted coral reef systems necessitate sustained efforts and resources. Our team is excited to offer continued support to this long-term management effort.

Related Articles

Understanding ocean changes and climate now harder
PDO and NPGO are not as effective at predicting environmental and ecological change as in the past A new study shows that two important indicators for understanding and predicting the effects of climate variability on eastern North Pacific marine ecosystems are less reliable than they were historically. Posted on 29 Mar
Hurricane response fund for marine debris removal
Severe storms can cause significant marine debris NFWF and NOAA's Marine Debris Program today announced $8.2 million in six new grants for the assessment, removal and proper disposal of marine debris that was caused by hurricanes Michael and Florence in Florida and North Carolina. Posted on 27 Mar
Harps seals: Rare visitors to New England shores
Remember to give our visitors their space, and allow them to rest undisturbed on beaches While we're used to seeing harbor and gray seals in New England, sometimes we get seal visitors from the Arctic. In late winter, it's not unusual—though it is rare—to see adult harp seals on our beaches. Posted on 21 Mar
Harassment of harbor seal leads to penalty
Washington man admits pursuing, shooting at harbor seal with an air rifle A Ferndale, Washington, man has agreed to pay a penalty of $5,625 for pursuing a harbor seal in the San Juan Islands while shooting at it with an air rifle. Posted on 19 Mar
Why do whales migrate?
Skin molt may drive migration for whales that forage in cold waters Whales undertake some of the longest migrations on earth, often swimming many thousands of miles, over many months, to breed in the tropics. The question is why—is it to find food, or to give birth? Posted on 28 Feb
Unmanned surface vehicles track marine mammals
Scientists successfully tested the feasibility of using Saildrones Scientists successfully tested the feasibility of using Saildrones to follow individual fur seals over long distances while simultaneously assessing their prey and habitat. Posted on 23 Feb
Type D: A new species of killer whale?
Biologists launched an expedition, searching for what could be a new species of killer whale In January 2019, an international team of scientists working off the tip of southern Chile got their first live look at what might be a new species of killer whale. Posted on 15 Feb
International whales of mystery
Where are the 'missing' breeding areas for humpback whales? Every year, humpback whales in the western Pacific Ocean migrate south to winter breeding grounds. Some whales spend their winters in the waters of the Mariana Archipelago, but we know less about humpback whales in the Marianas. Posted on 8 Feb
U.S. & Canada work to reduce whale mortalities
United States and Canada have a shared interest in recovering right whales A message from NOAA Fisheries Assistant Administrator Chris Oliver, who recently participated in a meeting with Canadian officials focused on the conservation and management efforts for the endangered North Atlantic right whale. Posted on 1 Feb
Investigation of gray whale strandings continues
California survey counts migrating whales for a new population assessment Gray whales have begun their annual southbound migration along the West Coast to Mexico. Science teams continue to investigate the cause of more than 200 strandings of dead and often thin gray whales during their northbound migration last spring. Posted on 26 Jan
Grapefruit Graphics 2019 - FooterSailing Holidays 2019 - BOTTOMGJW Direct - Yacht 2019 - Footer