Scientists Find Rare Species, Fish 'Nurseries' on New Coral Reef Survey

by Matt Dozier
National Marine Sanctuaries

Scientists from NOAA’s National Centers for Coastal Ocean Science teamed up with the staff of Flower Garden Banks National Marine Sanctuary Sept. 26 to Oct. 2 as they kicked off an ambitious new study in the sanctuary’s thriving, species-rich waters, making a number of surprising discoveries in the process.

The researchers traveled to the marine sanctuary, located more than 100 miles south of the Texas-Louisiana border in the warm waters of the Gulf of Mexico, aboard the NOAA ship Nancy Foster to conduct the first part of a comprehensive biogeographic assessment — an extensive survey that will catalog the abundance and distribution of the area’s fish, coral, and other invertebrate species. The data gathered from the study will give scientists a clearer picture of the habitats preferred by the sanctuary’s diverse array of marine residents, making it possible for marine resource managers to identify areas that may be particularly important to the health of the sanctuary ecosystem.

“It has really been a pleasure for us to have the opportunity to dive on the coral reef at random sites, which is something we’ve been talking about for years,” said Emma Hickerson, research coordinator for the sanctuary.

A marbled grouper drifts above the coral reef in Flower Garden Banks National Marine Sanctuary. Rarely seen elsewhere in the Gulf of Mexico and Caribbean, this species was sighted frequently during a recent expedition to the sanctuary. (Photo: NOAA/CCMA)

During the first portion of the project, NOAA scientists surveyed over 70 locations ranging from about 55 to 110 feet in depth representing a variety of habitats. Among the highlights of the expedition was the first documented sighting of a Nassau grouper and rare sightings of Goliath grouper - the largest member of the sea bass family in the Atlantic - within the waters of the sanctuary. Both species have undergone dramatic declines in abundance throughout their ranges and are now considered “species of concern” by the National Marine Fisheries Service. In addition, divers frequently sighted marbled grouper, a species that is rarely found anywhere else in the Gulf of Mexico or the Caribbean.

“One of the important things is that the study is confirming that this ecosystem is very healthy, and it’s supporting a good number of large, high-level predatory fish,” Hickerson said. “There’s a lot of areas in the Caribbean where you can’t find fish of that size because of overfishing.”

NOAA scientists record the abundance of marine life at one of the many sites chosen for the biogeographic assessment study. In all, divers conducted similar surveys at more than 70 locations around the Flower Garden Banks. (Photo: NOAA/FGBNMS)

Researchers also observed large numbers of juvenile fish in certain deepwater patches of dense, finger-like coral, suggesting that those areas may provide shelter for young fish and act as “nurseries” similar to the seagrass or mangrove habitats that are crucial to the survival of many species elsewhere. If the results of the project reveal this to be true, then it will allow local resource managers to determine how best to protect this important fish habitat and help ensure the continued health of this reef ecosystem.

“We were able to see some of the reef that we’ve never seen before,” Hickerson said. “This is the first quantitative data we have at any of these parts of the reef — the health of the coral and fish communities is just jaw-dropping.”

The biogeographic assessment is intended to be a two-year project, although funds have not yet been secured for the second year. Project scientists have thus far been relegated to the shallow waters of the sanctuary that are accessible to divers, which make up only about one percent of the sanctuary’s total area. Plans have been developed to conduct deepwater survey operations using remote equipment, but they will not be realized without additional funding.

“We only have part of the picture,” Hickerson said. “To have meaningful data and numbers to make solid statements we need more time in the water offshore — the study needs to be statistically robust.”

The NOAA ship Nancy Foster deploys a small boat for dive operations. The Nancy Foster was the primary research vessel for the study, supporting several teams of divers over the course of the week-long expedition. (Photo: NOAA/CCMA)

Designated as a sanctuary in 1992, Flower Garden Banks National Marine Sanctuary protects the northernmost coral reefs in the United States, in an area teeming with an estimated 250 species of fish, 23 species of coral and 80 species of algae, as well as large communities of sponges. The sanctuary is also one of the last remaining regions within the western Atlantic that is home to high densities of large predatory fish such as groupers, snappers and sharks, and boasts unparalleled coverage of reef-building corals. By comparison, while most Atlantic reefs exhibit only 5 to 10 percent coral cover, the Flower Garden Banks are covered by more than 50 percent on the bank summits and are nearly completely blanketed by coral in many deeper areas.

“There were comments from the research team after the dives about just how high the coral cover was,” Hickerson said. “In this world of declining coral reef health, here we have this astounding reef that is healthy with such high coverage — the sheer size of some of the corals was absolutely stunning.”

Regulations prohibit activities such as discharging pollutants, sea bed alteration, anchoring boats, or removing living or non-living resources from within the boundaries of the sanctuary. Both commercial and recreational fishing is permitted within sanctuary waters, although fishing using bottom trawls, longlines, spear guns or explosives is prohibited.

Click here for larger version

The unique ecosystem diversity of Flower Garden Banks makes the marine sanctuary an ideal place for scientists to study a wide range of species and habitats within a small area. One goal of the biogeographic assessment project is to investigate the possibility that Flower Garden Banks is becoming a refuge for species of Caribbean marine fish and invertebrates, many of which are disappearing from their natural habitat ranges due to reef damage and overfishing, and — like the marbled grouper — have begun appearing more frequently within the sanctuary. If scientists can determine why the Flower Garden Banks are able to support the biodiversity they do, it could help with future efforts to restore other more impacted locations throughout the Caribbean, Florida and the Gulf of Mexico.

Biological monitoring has been conducted at Flower Garden Banks since the 1970s, focusing primarily on monitoring corals, algae, and sponges to evaluate coral growth, diseases, and bleaching. Until the 1990s, however, surveys of the sanctuary’s fish community had generally been limited in scope to just a handful of sites covering a small area of the reef. The expanded survey from the new biogeographic assessment of Flower Garden Banks will provide a much clearer picture of the status of fish and coral populations in the sanctuary.  Collected data will complement the findings of previous research and will be instrumental in the ongoing efforts of sanctuary personnel to revise the sanctuary’s management plan — a document that will serve as a framework for guiding future management and activities of the sanctuary.

“We’re learning more about what we have in the sanctuary, and it’s helping us better characterize the resources that we are mandated to protect,” Hickerson said.

Those interested in learning more about the project should visit the project website or contact chris.caldow@noaa.gov. For more information on Flower Garden Banks National Marine Sanctuary, please visit http://flowergarden.noaa.gov or contact emma.hickerson@noaa.gov.

Top photo: Several horse-eye jacks swim past Flower Garden Banks National Marine Sanctuary GIS Specialist Doug Weaver as he dives to assist with species counts for a biogeographic assessment study. (Photo: NOAA/FGBNMS)