A Fish That Shapes The Reef

By Andrew E. Gray

Every three years, scientists from NOAA’s Coral Reef Ecosystem Program (CREP) visit Wake Atoll to survey corals, assess the fish populations, and collect oceanographic data for a long-term monitoring effort—the Pacific Reef Assessment and Monitoring Program (Pacific RAMP). Wake Atoll has clear water, healthy coral reefs, and is managed and conserved as part of the expansive U.S. Pacific Remote Islands Marine National Monument. It has a healthy reef fish community with plentiful sharks, jacks, and groupers. As a fish research diver, it’s my kind of paradise. Sitting in the middle of the subtropical North Pacific Ocean, 1,500 miles east of Guam and about 2,300 miles southwest of Honolulu, it may be the most remote place I’ve ever been. But for me, and a few other scientists lucky enough to visit the island, there is one thing that makes Wake a special place: Bolbometopon muricatm, the Bumphead parrotfish.

Bumphead parrotfish

Bumphead parrotfish (Bolbometopon muricatm) at Wake Atoll (Photo: NOAA Fisheries/Andrew E. Gray)

Bumphead parrotfish are an incredible and unique reef fish, differing from other parrotfish by their large size, appearance, diet, and by their ecological impact on coral reef ecosystems. There are a number of other parrotfish that sport a bump on their head, and these may be mistaken for a Bumphead parrotfish—that is until you actually see one. Bumpheads have a presence like no other fish on the reef and when they are around I can’t take my eyes off of them. The first thing I notice is their sheer size: growing to 4.2 feet long and up to a 100 pounds (that’s 130 cm and 46 kg for you scientists). Bumpheads are the world’s largest parrotfish and among the largest of all reef fish. When I get a little closer, I can’t help but focus on their incredible beaks. On coral reefs, all parrotfish species are tasked with the important job of keeping algae from overgrowing reef-building corals.

Corals chomped

Bumphead parrotfish chomp corals and help maintain the health and diversity of the reef ecosystem, Wake Atoll (Photo: NOAA Fisheries/Andrew E. Gray)

Parrotfish bite and scrape algae off of rocks and dead corals with their parrot-like beaks; grind the inedible calcium carbonate (reef material made mostly of coral skeletons) which is excreted as sand back onto the reef. Larger parrotfish species can take small chunks out of the reef, removing algae and the occasional piece of coral. Bumphead parrotfish are unique in that they are continuously crunching large bites out of the reef, about half of it from live coral. In fact, that’s what they do most of the day. Bite the reef. Excrete sand. Repeat. Over the course of a year a single fish can remove over 5 tons of calcium carbonate from the reef! But by selectively eating fast growing coral species over slower growing species, they help maintain a more diverse coral reef ecosystem. Also, by munching down tons of dead corals every year each fish makes room for young corals to settle, grow and build up the reef. This means breaking down “dead reef” into sand rather than it breaking off in a storm and damaging other parts of the reef. And since Bumpheads often travel in groups, sometimes numbering into hundreds and traveling multiple kilometers in a day, this species can have quite an impact on the reef ecosystem. Bumphead parrotfish literally shape the reef.

Bumphead

Large bump on the head of a Bumphead parrotfish (Photo: NOAA Fisheries/Andrew E. Gray)

Then, of course, there is the fish’s namesake, its bump. All Bumphead parrotfish sport a large protrusion on their forehead which is similar in function to a pair of horns on a bighorn sheep. The largest males have the biggest bumps and will occasionally use them as battering rams around spawning time, smashing headfirst into rivals in an attempt to show their dominance and retain territorial and breeding rights. This incredible behavior was observed by CREP scientists in 2009 and first documented and filmed by researchers at Wake in 2011. During these mating events, the parrotfish gather or aggregate around a spawning site and can number into the hundreds, an uncommon site anywhere in the world and one that I hope to see sometime at Wake.

Historically, Bumphead parrotfish were plentiful throughout much of the Western Pacific, Indian Ocean, and Red Sea. In recent decades, fishing led to sharp declines in abundance and they are now only common in protected or very remote areas. Bumpheads have a few traits that make them particularly vulnerable to overfishing, which has led to local disappearances in many parts of their range. Bumphead parrotfish can live to be 40 years old; they do not reach sexual maturity until 5-8 years old and likely have low natural mortality as adults so there is not high natural turnover in the population. However, most detrimental to their survival in a human-dominated world is their aggregating behavior and preference for shallow water. Groups of Bumpheads could be easily netted, as they feed during the day, and at night sleeping parrotfish are easy targets for spear fishermen. With the introduction of scuba gear in the 1960’s and 1970’s there was a steep decline in Bumphead abundances as entire schools could be removed in a single night while they slept. Juvenile Bumpheads are also hard to find or study throughout much of their range and raises concerns that some adult populations are too far from juvenile habitats. This distance prevents new youngsters from entering the population to replace adults that have been caught. In areas where juveniles can be commonly found, such as Papua New Guinea and the Solomon Islands, they are associated with mangrove, rubble, and sheltered lagoon habitats. And this is why Wake Atoll may be such a hotbed of Bumpheads.

Reef at Wake Atoll

Coral reef at Wake Atoll in the Pacific Remote Islands Marine National Monument (Photo: NOAA Fisheries/James Morioka)

In addition to having a sizable healthy coral reef around the island, Wake Atoll has an expansive, sheltered lagoon. This may be the perfect habitat for the juvenile parrotfish and allows Wake to have a healthy, self-supplying population of Bumpheads. And since Wake is protected from fishing, it may be as close to a pristine home as the Bumphead parrotfish are going to encounter in today’s world. Wake actually has the highest concentration of Bumphead parrotfish in U.S. waters and possibly the world (although certain areas of the Great Barrier Reef in Australia also have very healthy adult populations). During my time at Wake Atoll, I had a number of chances to see them, from loose groups of just a few individuals, to a school of thirteen.

School too

School of Bumphead parrotfish at Wake Atoll (Photo: NOAA Fisheries/Andrew E. Gray)

As I write this, the NOAA Ship Hi‘ialakai heads west to Guam, our next survey site where I’ll be spending 8 days surveying reef fish. Bumpheads were once thought to be extinct around Guam due to overfishing, but there have been a few sightings by CREP and partners in the past few years, of both adults and juveniles. So while my expectations of encountering these giant bulbous-headed, coral-chomping fish are low, I sure hope I do, given how important they are to the natural function of coral reef ecosystems.

References
  1. Bellwood, D., & Choat, J. (2011). Dangerous demographics: the lack of juvenile humphead parrotfishes Bolbometopon muricatum on the Great Barrier Reef. Coral Reefs, 30(2), 549-554.
  2. Bellwood, D. R., Hoey, A. S., & Choat, J. H. (2003). Limited functional redundancy in high diversity systems: resilience and ecosystem function on coral reefs. Ecology Letters, 6(4), 281-285.
  3. Bellwood, D. R., Hoey, A. S., & Hughes, T. P. (2011). Human activity selectively impacts the ecosystem roles of parrotfishes on coral reefs. Proceedings of the Royal Society B: Biological Sciences. doi: 10.1098/rspb.2011.1906
  4. Donaldson, T. J., & Dulvy, N. K. (2004). Threatened fishes of the world: Bolbometopon muricatum (Valenciennes 1840)(Scaridae). Environmental Biology of Fishes, 70(4), 373-373.
  5. Green, A. L., & Bellwood, D. R. (2009). Monitoring functional groups of herbivorous reef fishes as indicators of coral reef resilience: a practical guide for coral reef managers in the Asia Pacific Region: IUCN.
  6. Kobayashi, D., Friedlander, A., Grimes, C., Nichols, R., & Zgliczynski, B. (2011). Bumphead parrotfish (Bolbometopon muricatum) status review. NOAA Technical Memorandum NMFS-PIFSC-26. NOAA.
  7. Muñoz, R. C., Zgliczynski, B. J., Laughlin, J. L., & Teer, B. Z. (2012). Extraordinary Aggressive Behavior from the Giant Coral Reef Fish, Bolbometopon muricatum, in a Remote Marine Reserve. PLoS One, 7(6), e38120. doi: 10.1371/journal.pone.0038120
  8. Munoz, R. C., Zgliczynski, B. J., Teer, B. Z., & Laughlin, J. L. (2014). Spawning aggregation behavior and reproductive ecology of the giant bumphead parrotfish, Bolbometopon muricatum, in a remote marine reserve. PeerJ, 2, e681.
  9. Sundberg, M., Kobayashi, D., Kahng, S., Karl, S., & Zamzow, J. (2015). The Search for Juvenile Bumphead Parrotfish (Bolbometopon muricatum) in the Lagoon at Wake Island.

Assessing impacts of coral bleaching: NOAA scientists embark on a three-month survey of coral reef ecosystems in the Hawaiian Archipelago

by Drs. Bernardo Vargas-Ángel and Rusty Brainard
FFS_2013_IMG_2852E

French Frigate Shoals in the Northwestern Hawaiian Islands (NOAA Photo)

Today, scientists from the NOAA Pacific Islands Fisheries Science Center’s Coral Reef Ecosystem Program boarded the NOAA Ship Hi‘ialakai to begin a 75-day Hawaiian Archipelago Reef Assessment and Monitoring Program (HARAMP) research mission. The goal of this mission is to document the status and trends of the coral reef ecosystems of the populated main Hawaiian Islands and the remote Papahānaumokuākea Marine National Monument in the uninhabited Northwestern Hawaiian Islands.

As part of the National Coral Reef Monitoring Program of NOAA’s Coral Reef Conservation Program, this HARAMP expedition will conduct the first statewide surveys to assess the overall impacts of two back-to-back mass coral bleaching events, which occurred in 2014 and 2015 and were caused by unusually warm water temperatures. When water temperatures reach 1°C warmer than their usual summertime maximum, many corals begin to lose the symbiotic algae living in their tissues, making them look white — that is, they become “bleached.”

This expedition will be the 6th monitoring cruise in the main Hawaiian Islands and the 10th monitoring cruise in the Northwestern Hawaiian Islands led by the PIFSC Coral Reef Ecosystem Program and partner agencies since 2000. It’s designed to provide an ongoing, consistent flow of information to document the status and long-term trends of the coral reefs and changing environmental conditions.

These statewide monitoring surveys will complement the local and site-specific coral reef monitoring efforts led by our partner agencies and institutions. Partners participating in this mission include scientists from the State of Hawai‘i Division of Aquatic ResourcesThe Nature ConservancyHawai‘i Institute of Marine Biology, and San Diego State University, among others.

PHR_2013_IMG_3047E

Autonomous Reef Monitoring Structure installed on left, calcification accretion unit on right (NOAA Photo)

Scientists will survey the coral reefs around each of the main Hawaiian Islands, including Ni‘ihau, Kaua‘i, O‘ahu, Molokai, Lāna‘i, Maui, Kaho‘olawe, and Hawai‘i Islands, and the coral reefs at French Frigate Shoals, Lisianski/Neva Shoals, Pearl and Hermes Atoll, and Kure Atoll in the Northwestern Hawaiian Islands. Each day, they will deploy 4–5 small boats with a team of scientific divers from the Hi`ialakai to conduct in-water surveys of the different reef zones, such as forereef, backreef, and lagoons around the different sides of each island or atoll ecosystem. We often find that the coral reefs and associated organisms vary greatly between leeward and windward sides of islands that are exposed to different environmental conditions, such as waves and currents.

Coral Reef

Under the direction of Chief Scientists Drs. Bernardo Vargas-Ángel in the main Hawaiian Islands and Brett Schumacher in the Northwestern Hawaiian Islands, the different dive teams will conduct underwater surveys of reef fishes, corals, other invertebrates, algae, and microbes. They will deploy and retrieve Autonomous Reef Monitoring Structures, or ARMS, to assess the biodiversity of ‘cryptic’ coral reef species that live within the reef (small crabs, shrimp, snails, etc.).

Autonomous Reef Monitoring Structures (ARMS) installed at Pearl and Hermes Atoll, NWHI (NOAA Photo)

Autonomous Reef Monitoring Structures (ARMS) installed at Pearl and Hermes Atoll, NWHI (NOAA Photo)

Close-up of ARMS unit at Pearl and Hermes Atoll, NWHI (NOAA Photo)

Close-up of ARMS unit at Pearl and Hermes Atoll, NWHI (NOAA Photo)

Calcification accretion unit installed at French Frigate Shoals, NWHI (NOAA Photo)

Calcification accretion unit installed at French Frigate Shoals, NWHI (NOAA Photo)

 

 

 

 

 

 

Additionally, oceanographers aboard the Hi`ialakai will collect data on water temperature, salinity, carbonate chemistry, and other physical characteristics of the coral reef environment with an assortment of oceanographic monitoring instruments. Among other things, they’re monitoring the ecological impacts of ocean acidification by determining the rates of reef growth and reef removal using tools called calcification accretion units and bioerosion monitoring units, respectively, which are deployed on the reef substrate for three years.

Data collected by the scientific staff of this cruise are pivotal to long-term biological and oceanographic monitoring of coral reef ecosystems in the Hawaiian Archipelago. This 2016 HARAMP expedition will help inform scientists, resource managers, and policy makers about changes that have occurred compared with similar surveys conducted in 2000, 2001, 2002, 2003, 2004, 2005 (main Hawaiian Islands only), 2006, 2008, 2010, and 2013.

Hawaiian Archipelago Reef Assessment and Monitoring Program Cruise 2016 Timeline

In particular, data on the abundance and spatial distribution of reef fishes and benthic organisms will allow scientists to evaluate potential changes in the condition and integrity of coral reef ecosystems across the Hawaiian Archipelago. It will also enable federal and state resource managers to more effectively manage and conserve reef-associated animal and plant life in the region. This year’s surveys are particularly important since many of the coral reefs experienced mass coral bleaching in both 2014 and 2015, and these surveys will provide an opportunity to assess the net change in coral cover for each of the islands across the archipelago.

 

From the Village to the Pacific, coordinating coral reef assessments in Tutuila, American Samoa

by Kelvin Gorospe and Adel Heenan
1.Gorospe_survey

Kelvin Gorospe sets transects for a fish survey.

Following the American Samoa portion of the recent Reef Fish Survey cruise, Adel and I disembarked NOAA ship Oscar Elton Sette to remain in Pago Pago, American Samoa. From May 9 to 13, we met with partners from the American Samoa Coral Reef Advisory Group (CRAG), Department of Marine and Wildlife Resources, the Environmental Protection Agency, NOAA’s Coral Reef Conservation Program, National Marine Sanctuary of American Samoa, and National Park Service. During this time, we facilitated a workshop to initiate steps to achieve cross-scale coordination between our programs and cross-scale integration of our datasets. By bringing multiple agencies and institutions together, all of whom are engaged in coral reef ecosystem monitoring in Tutuila, American Samoa, we used our collective experience (more than 120 years!) in coral reef monitoring to think about cross-scale ecosystem monitoring. How can we combine our resources to complement each other’s monitoring programs? Can we integrate datasets collected at different scales, and if not, are there steps that we can take to facilitate this integration down the road?

2.Group

Several participants of the data integration workshop held in Pago-Pago, American Samoa.

To begin taking steps in the right direction, we had to figure out how to compare different datasets and understand the monitoring objectives of different agencies. Effective monitoring objectives determine the scope of inference for the data collected and more often than not, monitoring programs are optimized to report at a specific spatial scale. For example, data collected by the Pacific Islands Fisheries Science Center’s Coral Reef Ecosystem Program (CREP) for the Pacific Reef Assessment and Monitoring Program (Pacific RAMP) are primarily designed to report on key metrics of ecosystem condition at an island or sub-island scale for each of the U.S.-affiliated islands and atolls in the Pacific. In contrast, data collected by various monitoring agencies operating in Tutuila are designed to report metrics at the village/bay or site-specific scale. Coordinating efforts across scales is an important component of ecosystem-based management that allows for more effective comparisons between efforts. For example, how does the status of reef fish populations in a particular marine protected area compare to reef fish populations for the rest of the island, or islands in an archipelago? Such coordination and comparisons allow for inference at an ecosystem-relevant scale. Blending datasets and coordinating monitoring programs is, however, easier said than done.

One barrier to seamless integration that was identified at the workshop, was the existence of multiple survey methods. When identical methods are used to collect data for different scales, the data can be blended and compared on these different scales. Last year, the National Marine Sanctuaries of American Samoa partnered with CREP to collect baseline data for Aunu‘u and Fagatele Bay. Typically CREP collects island-scale data for the National Coral Reef Monitoring Program (NCRMP). However, since the method used to collect both the Pacific RAMP and National Marine Sanctuaries datasets were identical, the Sanctuaries’ baseline data could be easily compared to the island-scale data collected for NCRMP. For many of the monitoring programs operating in Tutuila, however, blending datasets will not be so easy. For example, many of them use belt-transects to conduct fish surveys, while CREP uses a stationary point count method. While both acquire the same type of information, the use of different methods makes blending the data a bit challenging.

3.Lawrence_CRAG

Workshop participant, Alice Lawrence from the Coral Reef Advisory Group, presenting a SWOT evaluation of the American Samoa Coral Reef Monitoring Program’s dataset.

Over several days, partners presented the details (e.g., sampling design, quantitative objectives, etc.) of their individual datasets, reviewed examples and strategies for how datasets can be integrated, and conducted SWOT (strengths, weaknesses, opportunities, and threats) evaluations of their monitoring programs. Our purpose was to understand the intricacies of each other’s datasets before considering how we could potentially integrate.

The workshop culminated in a structured discussion on how to integrate community, jurisdictional, and federal coral reef ecosystem monitoring datasets. Participants were asked to detail concrete, short, and long-term steps that can be taken to overcome existing barriers to integrating our datasets. Recommendations ranged from conducting a calibration study between several of our datasets to facilitate the comparison of our different survey methods to publishing an information brief that co-reports multiple datasets for a single village’s marine resources. These recommendations fell into four broad categories that encapsulate the different components of a monitoring program – (1) communication strategy, (2) data integrity, (3) data relevance, and (4) non-data resources (e.g., creating a full-time interagency monitoring team in Tutuila) – and will be detailed in a forthcoming workshop report.

We are now working on an information brief, that will provide both an outreach tool and serve as a pilot study for how our multiple datasets could be co-reported. The information brief will report on biological and socio-economic indicators collected across multiple efforts for a single village. Our plan is to produce this informational product for a village where multiple datasets already exist. If successful, we hope to roll out similar products for other villages.

4.Data_Tutuila

A map of several different monitoring datasets collected around Tutuila, American Samoa

Funded by NOAA’s Coral Reef Conservation Program, the workshop and its outcomes are an important link between jurisdictional scientists in American Samoa focused on local monitoring efforts and PIFSC scientists focused on Pacific-wide and national efforts. Based on the next steps and recommendations identified at the workshop, the benefits to coordinating across multiple scales are clear: not only will integration allow us to understand more about the ecosystems in which we operate, but will also allow us to collectively achieve more.

SE16-02: American Samoa Reef Fish Survey Summary

by Adel Heenan and Marc Nadon

For the past three weeks, the NOAA Ship Oscar Elton Sette has been the support platform for the Pacific Islands Fisheries Science Center’s reef fish survey project. This research project was led by the NOAA Coral Reef Ecosystem Program (CREP), with partner agency representatives from the American Samoa Department of Marine and Wildlife Resources (DMWR) and the Bigelow Laboratory of Ocean Sciences. The mission was similar to the Pacific RAMP work, but with a particular focus on surveying reef fish assemblages.

Divers collected length observations for all reef fishes recorded during their underwater surveys. To do so accurately, trained divers regularly practice fish sizing using wooden cut-outs in-between research cruises. Length measurements for each reef fish surveyed allows an estimation of biomass by using pre-determined length-weight relationships. Furthermore, it is also used to estimate the size composition of fish populations and obtain a key indicator of population status: average length of exploited size classes. The reason we use this indicator is intuitive: as the exploitation rate of a fish population increases, fewer individual fish have a chance to reach older ages, and therefore, fewer individuals reach larger sizes. Mathematical expressions developed in the 1950s by fisheries scientists can actually relate average length to current fishing mortality rates, and these can be used in computer population simulations to investigate current stock status and generate management advice.

4.Survey_P.Ayotte

Reef fish survey divers regularly train in estimating fish size by using wooden cut-outs of known sizes (NOAA Photo by Paula Ayotte).

Outlined below is a summary of our recently completed survey efforts. More detailed survey results will be available in a forthcoming survey report.

Sampling effort

  •  Ecological monitoring took place in American Samoa from April 15 2016- May 5 2016.
  • Data were collected at 202 sites. Surveys were conducted at Ofu and Olosega (n=11), Rose (n=47), Tau (n=50) and Tutuila (n=94).
  • At each site, the fish assemblage was survey by underwater visual census and the benthic community rapidly assessed.
  • At a subset of sites (n=51), paired comparisons of fish surveys performed using closed circuit re-breathers versus open circuit SCUBA were conducted. Those data will be analyzed and presented in a separate publication.
TCW_rebreather

Diver conducts reef fish survey with a closed circuit re-breather (NOAA photo by Tate Wester).

Overview of the data collected

Primary consumers include herbivores (which eat plants) and detritivores (which bottom feed on detritus), and secondary consumers are largely omnivores (which mostly eat a variety of fishes and invertebrates) and invertivores (which eat invertebrates).

Spatial sampling design

Survey site locations are randomly selected using a depth-stratified design. During project planning and the project itself, logistic and weather conditions factor into the allocation of monitoring effort around sectors of each island or atoll. The geographic coordinates of sample sites are then randomly drawn from a map of the area of target habitat per study area. The target habitat is hard-bottom reef, the study area is typically an island or atoll, or in the case of larger islands, sectors per island, and the depth strata are shallow (0-6 m), mid (6-18 m), and deep (18-30 m).

Sampling methods

A pair of divers surveys the fish assemblage at each site using a stationary-point-count method (Figure 5). Each diver identifies, enumerates, and estimates the total length of fishes within a visually estimated 15-m-diameter cylinder with the diver stationed in the center. These data are used to calculate fish biomass per unit area (g m-2) for each species. Mean biomass estimates per island are calculated by weighting averages by the area per strata. Island-scale estimates presented here represent only the areas surveyed during this project. For gaps or areas not surveyed during this project, data from this and other survey efforts will generally be pooled to improve island-scale estimates.

Fig5.REA_method

Figure 5. Method used to monitor fish assemblages and benthic communities at the Rapid Ecological Assessment (REA) sites.

Each diver also conducts a rapid visual assessment of reef composition, by estimating the percentage cover of major benthic functional groups (encrusting algae, fleshy macroalgae, hard corals, turf algae and soft corals) in each cylinder. Divers also estimate the complexity of the surface of the reef structure, and they take photos along a transect at each site that are archived to allow for future analysis.

About the monitoring program

Pacific RAMP forms a key part of the National Coral Reef Monitoring Program of NOAA’s Coral Reef Conservation Program (CRCP), providing integrated, consistent, and comparable data across U.S. Pacific islands and atolls. CRCP monitoring efforts aim to:

  • Document the status of reef species of ecological and economic importance.
  • Track and assess changes in reef communities in response to environmental stressors or human activities.
  • Evaluate the effectiveness of specific management strategies and identify actions for future and adaptive responses.

In addition to the fish community surveys outlined here, Pacific RAMP efforts include interdisciplinary monitoring of oceanographic conditions, coral reef habitat assessments and mapping. Most data are available upon request.

For more information:

CREP publications

CREP monitoring reports

CREP fish team

Fish team lead and fish survey data requests: ivor.williams@noaa.gov, adel.heenan@noaa.gov

 

Coral reef monitoring surveys completed around the islands and atolls of American Samoa

By Bernardo Vargas-Ángel
Operating area of the HA-15-01 ASRAMP Legs II and III.

Operating area of the HA-15-01 ASRAMP Legs II and III.

With work complete in the U.S. territory of American Samoa, the NOAA Ship Hi‘ialakai stopped in the port of Pago Pago Harbor for a short pause between Legs III and IV of PIFSC cruise HA-15-01. Led by the PIFSC Coral Reef Ecosystem Division (CRED), this mission marks the seventh monitoring cruise in the American Samoa region by PIFSC staff and partner agencies since 2002.

Activities to monitor the coral reef ecosystems of American Samoa began on February 17 and concluded on March 30, completing Leg I and comprising Legs II and III of this longer Pacific Reef Assessment and Monitoring Program (Pacific RAMP) expedition. Around Tutuila, Aunu‘u, Ofu-Olosega, Swains, and Ta‘u Islands, and Rose Atoll, the CRED scientists conducted ecosystem surveys of fishes, benthic and coral communities, and microbes, along with the deployment of oceanographic instruments and biological installations.

Shallow coral reef communities at Rose Atoll, conspicuously dominated by the pink-colored encrusting coralline algae.

Shallow coral reef communities at Rose Atoll, conspicuously dominated by the pink-colored encrusting coralline algae.

A pair of the reticulated butterflyfish (Chaetodon reticulatus) at Swains Island.

A pair of the reticulated butterflyfish (Chaetodon reticulatus) at Swains Island.

At Rapid Ecological Assessment (REA) sites, surveys for reef fishes and benthic coral communities documented the richness, abundance, density, and sizes of the biota and assemblages as well as the percent composition of bottom-dwelling organisms and the health conditions of coral colonies. Broad-scale towed-diver surveys recorded observational data on large-bodied fishes (>50 cm total length), percent composition of the seafloor, conspicuous macroinvertebrates, and coral stress.

In addition, teams studied microbial communities, diversity of cryptic invertebrates, water temperature, salinity, and carbonate chemistry. They are also working to assess the potential early effects of ocean acidification on cryptobiota (e.g. small, hidden organisms) and the rates of reef carbonate deposition, bioerosion, and coral calcification.

Across the Territory of American Samoa, this mission completed more than 60 towed-diver surveys totaling more than 130 km of coastline, 325 fish surveys, and 180 benthic surveys. The Ocean and Climate Change team deployed four climate monitoring stations around Tutuila, and four around Ofu-Olosega and Ta‘u, containing arrays of subsurface temperature recorders (STRs), calcification accretion units (CAUs), autonomous reef monitoring structures (ARMS), and bioersion monitoring units (BMUs). Critical findings during this mission included observations of coral bleaching, local warm water temperatures, and the number and distribution of corallivore crown-of-thorns sea stars (COTS).

Bleached and partly dead staghorn Acropora outside Fagatele Bay, Tutuila, American Samoa.

Bleached and partly dead staghorn Acropora outside Fagatele Bay, Tutuila, American Samoa.

Bleaching of scleractinian corals, averaging 10% of colonies, was reported in shallow (3-6 m) reef habitats of Tutuila Island—particularly within Fagatele and Fagasa Bays—as well as the southwest coast of the island and primarily affected species of branching and table Acropora, Isopora, Montastrea, Porties, and Pocillopora. Although bleaching conditions did not appear to be widespread, current NOAA Coral Reef Watch forecasts predict persistent warm conditions, which could potentially result in more severe and extensive coral bleaching across the region. CRED scientists recorded only occasional sightings of COTS and their feeding scars on corals, despite the ongoing outbreak conditions reported by staff of the National Park Service and the National Marine Sanctuary of American Samoa. In contrast to other regions where COTS outbreaks have been reported by CRED scientists, including Guam, the Commonwealth of the Northern Mariana Islands, and Kingman Reef, it appears that in American Samoa, the sea stars prefer to feed at night and hide under ledges and overhangs during the day, making them inconspicuous during daylight surveys.

Preliminary results from surveys conducted by CRED fish team divers, during PIFSC cruise HA-15-01, are provided in the fish monitoring brief below.

Pacific Reef Assessment and Monitoring Program
Fish monitoring brief: American Samoa 2015

By Adel Heenan

About this summary brief
The purpose of this summary brief is to outline the most recent survey efforts conducted by the Coral Reef Ecosystem Division (CRED) of the NOAA Pacific Islands Fisheries Science Center as part of the long-term Pacific Reef Assessment and Monitoring Program (Pacific RAMP). More detailed survey results will be available in a forthcoming status report.

Sampling effort

  • Ecological monitoring took place in American Samoa from February 15 2015 to March 30 2015.
  • Data were collected at 338 sites. Surveys were conducted at Ofu and Olosega (n=52), Rose (n=47), Swains (n=32), Tau (n=46) and Tutuila (n=162).
  • At each site, the fish assemblage was surveyed by underwater visual census and the benthic community was assessed.

Overview of data collected
Primary consumers include herbivores (which eat plants) and detritivores (which bottom feed on detritus), and secondary consumers are largely omnivores (which mostly eat a variety of fishes and invertebrates) and invertivores (which eat invertebrates).

Figure 1. Mean total fish biomass at sites surveyed.

Figure 1. Mean total fish biomass at sites surveyed.

Figure 2. Mean hard coral cover at sites surveyed.

Figure 2. Mean hard coral cover at sites surveyed.

Spatial sample design
Survey site locations are randomly selected using a depth-stratified design. During cruise planning and the cruise itself, logistic and weather conditions factor into the allocation of monitoring effort around sectors of each island or atoll. The geographic coordinates of sample sites are then randomly drawn from a map of the area of target habitat per study area. The target habitat is hard-bottom reef, the study area is typically an island or atoll, or in the case of larger islands, sectors per island, and the depth strata are shallow (0-6 m), mid (6-18 m), and deep (18-30 m).

Sampling methods
A pair of divers surveys the fish assemblage at each site using a stationary-point-count method. Each diver identifies, enumerates, and estimates the total length of fishes within a visually estimated 15-m-diameter cylinder with the diver stationed in the center. These data are used to calculate fish biomass per unit area (g m-2) for each species. Mean biomass estimates per island are calculated by weighting averages by the area per strata. Island-scale estimates presented here represent only the areas surveyed during this cruise. For gaps or areas not surveyed during this cruise, data from this and other survey efforts will generally be pooled to improve island-scale estimates.

Figure 3. Mean consumer group fish biomass (± standard error). Primary consumers are herbivores and detritivores, and secondary consumers are omnivores and invertivores.

Figure 3. Mean consumer group fish biomass (± standard error). Primary consumers are herbivores and detritivores, and secondary consumers are omnivores and invertivores.

Figure 4. Mean fish biomass per size class (± standard error). Fish measured by total length (TL) in centimeters (cm).

Figure 4. Mean fish biomass per size class (± standard error). Fish measured by total length (TL) in centimeters (cm).

Each diver also conducts a rapid visual assessment of reef composition, by estimating the percentage cover of major benthic functional groups (encrusting algae, macroalgae, hard corals, turf algae and soft corals) in each cylinder. Divers also estimate the complexity of the surface of the reef structure, and they take photos along a transect at each site that are archived to allow for future analysis.

About the monitoring program
Pacific RAMP forms a key part of the National Coral Reef Monitoring Plan of NOAA’s Coral Reef Conservation Program (CRCP), providing integrated, consistent, and comparable data across U.S. Pacific islands and atolls. CRCP monitoring efforts have these aims:

  • Document the status of reef species of ecological and economic importance
  • Track and assess changes in reef communities in response to environmental stressors or human activities
  • Evaluate the effectiveness of specific management strategies and identify actions for future and adaptive responses

In addition to the fish community surveys outlined here, Pacific RAMP efforts include interdisciplinary monitoring of oceanographic conditions, coral reef habitat assessments and mapping. Most data are available upon request.

For more information
Coral Reef Conservation Program
Pacific Islands Fisheries Science Center
CRED publications
CRED monitoring reports
CRED fish team
Fish team lead and fish survey data requests: ivor.williams@noaa.gov, adel.heenan@noaa.gov

Scientists complete coral reef ecosystem monitoring work around the U.S. Phoenix Islands

By Kelvin Gorospe

The Pacific Islands Fisheries Science Center’s (PIFSC) Coral Reef Ecosystem Division (CRED) recently completed the Phoenix Islands portion of their Pacific Reef Assessment and Monitoring Program (Pacific RAMP) research cruise. The areas they surveyed included: Johnston Atoll, Howland Island, and Baker Island. All three islands are part of the Pacific Remote Islands Marine National Monument, which is co-managed by NOAA and the U.S. Fish and Wildlife Service (USFWS), as well as the National Wildlife Refuge System administered by the USFWS. These areas are among the most remote locations under U.S. jurisdiction and offer a unique opportunity to study and better understand coral reef ecosystems removed from direct human impacts.

Figure 1: Launching and recovering teams of scientists from NOAA R/V Hi‘ialakai. Photo credit Kelvin Gorospe.

Figure 1: Launching and recovering teams of scientists from NOAA R/V Hi‘ialakai. Photo credit Kelvin Gorospe.

Figure 2: Group photo of scientific divers on the fantail of the ship. Photo credit Jim Bostick.

Figure 2: Group photo of scientific divers on the fantail of the ship. Photo credit Jim Bostick.

During the expedition, small boats were launched from NOAA ship Hi‘ialakai carrying teams of scientists to survey reef fishes, benthic and microbial communities, and study the effects of ocean acidification and warming on reef ecosystems (Fig 1). A total of 17 scientific divers, one data manager, and two terrestrial biologists participated in operations (Fig 2). For the U.S. Phoenix Islands portion of the cruise, fish data are highlighted below. Blog posts from the upcoming legs of this 103-day research expedition will highlight information from other reef assessment surveys.

Over the course of 13 diving days, the fish team surveyed a total of 102 rapid ecological assessment (REA) sites (31 at Johnston Atoll, 35 at Howland Island, and 36 at Baker Island). The team used a stratified random survey design, whereby the reefs around each island are divided into three depth zones (0-6 m; 6-18 m; and 18-30 m) and the total number of sites surveyed in each depth zone is proportionate to the total amount of reef area found in that depth zone. Site locations are then spatially randomized around the island. Click here for more details on the methodology of fish REA surveys.

Figure 3: Total fish biomass (all species) at all sites surveyed around Howland Island.

Figure 3: Total fish biomass (all species) at all sites surveyed around Howland Island.

Figure 4: Total fish biomass (all species) at all sites surveyed around Baker Island.

Figure 4: Total fish biomass (all species) at all sites surveyed around Baker Island.

At Howland and Baker Islands, the subsurface eastward-flowing Equatorial Undercurrent encounters the submerged portions of these undersea mountains to create areas of intense upwelling of nutrient-rich waters that help sustain high biomasses of reef fishes. This is clearly shown in the bubble plots above (Fig 3 and Fig 4), depicting high levels of fish biomass around both islands. Each circle on the graph is centered on a dive site.

Figure 5: Manta rays swimming through a fish survey at Howland Island. Photo credit Louise Giuseffi.

Figure 5: Manta rays swimming through a fish survey at Howland Island. Photo credit Louise Giuseffi.

Figure 6: Fish REA diver collecting data on fish species ID, sizes, and abundance at Johnston Atoll. Photo credit Louise Giuseffi.

Figure 6: Fish REA diver collecting data on fish species ID, sizes, and abundance at Johnston Atoll. Photo credit Louise Giuseffi.

Among other large-bodied species, schools of manta rays were frequently reported around both Howland and Baker Islands (Fig 5). At each site, two fish divers collected replicate data on the sizes and numbers of fish species that swam through their survey area over the course of five minutes (Fig 6). The size of the circle is proportionate to the calculated total biomass of fish (g per m2) at each site. These graphs demonstrate the high reef fish biomasses in these upwelling areas of the Pacific Remote Islands Marine National Monument.

Figure 7: Total fish biomass (all species) at all sites surveyed around Johnston Atoll.

Figure 7: Total fish biomass (all species) at all sites surveyed around Johnston Atoll.

In contrast, Johnston Atoll, which doesn’t experience this strong upwelling of nutrients (Fig 7), sustains lower levels of reef fish biomass than Howland and Baker. However, its importance is highlighted by the fact that it is known to be an important genetic stepping stone between the central Pacific and the Hawaiian Islands, maintaining evolutionary connectivity between these areas. During our time at Johnston on this cruise, CRED scientists spotted three coral species (Acropora speciosa, Acropora retusa, and Pavona diffluens) recently listed as threatened under the Endangered Species Act.

In addition, CRED scientists reported frequent sightings of overturned Acropora table corals and observed that much of the coral on the northwest side of the atoll experienced recent damage, likely as a result of the large ocean swell from the northwest that came through as we were leaving Oahu at the end of January. Protection of these areas from the degrading effects of fishing and extraction is important to ensuring that the reef can recover from natural environmental impacts such as these large ocean swell events.

The CRED team will remain at sea until May 3, 2015, continuing to conduct coral reef ecosystem monitoring surveys throughout American Samoa (Tutuila, Ofu, Olosega, Ta‘u, and Swains Islands and Rose Atoll) as well as the U.S. Line Islands (Jarvis Island, Palmyra Atoll, and Kingman Reef). Stay tuned for more updates from the field.