Reef monitoring at Wake Island: preliminary results from fish surveys

By Dione Swanson

After departing Honolulu on March 5, the NOAA Ship Hi’ialakai arrived at Wake Island on March 14. It was the first stop for PIFSC cruise HA-14-01, a Pacific Reef Assessment and Monitoring Program (Pacific RAMP) expedition that also recently visited Guam and is currently focused on the southern islands of the Commonwealth of the Northern Marianas Islands. At Wake Island, staff members of the PIFSC Coral Reef Ecosystem Division (CRED) and partners conducted surveys of reef fish assemblages, coral populations, and benthic communities as well as deployed instruments and collected water samples to monitor effects of climate change and ocean acidification on coral reef ecosystems.

Our first 2 planned operational days on Wake Island were canceled because of poor weather conditions (strong winds and high seas). Relatively good weather returned by March 16, and we then were able to complete 4.5 days of small-boat operations before leaving for Guam on March 20. Over the course of our time at Wake Island, scientists accomplished the following field activities during a combined 229 dives: reef fish surveys at 45 Rapid Ecological Assessment (REA) sites; benthic surveys at 20 REA sites; collection of 12 water samples and 1 benthic sample for analysis of microbial communities; retrieval of 7 subsurface temperature recorders (STRs), 6 autonomous reef monitoring structures (ARMs), 15 calcification accretion units (CAUs), and 1 sea-surface temperature (SST) buoy; installation of 4 National Coral Reef Monitoring Plan climate stations—each of which includes 3 ARMs, 5 CAUs, 5 bioerosion monitoring units, and 3 STRs; and collection of 20 water samples for analysis of dissolved inorganic carbon; and completion of 11 shallow-water conductivity, temperature, and depth (CTD) casts.

Highlights of our research dives at Wake Island included incredible water visibility (>45 m), high coral cover that consisted of abundant large colonies with low partial mortality, overall low prevalence of coral disease and bleaching, and large patches of soft corals. There were only a few sightings of bumphead parrotfish (Bolbometopon muricatum) and Napoleon wrasse (Cheilinus undulatus).

Preliminary results from the surveys of reef fishes conducted by scuba divers at Wake Island (depth range: 0–30 m) during this cruise are provided in the below fish monitoring brief, which was issued on March 25 as PIFSC Data Report DR-14-007 (click here, to download a PDF file of this report). Wake Island is 1 of 7 islands, atolls, and reefs that make up the Pacific Remote Island Areas and, under the jurisdiction of the United States, are protected as the Pacific Remote Islands Marine National Monument.

Pacific Reef Assessment and Monitoring Program
Fish monitoring brief: Pacific Remote Island Areas 2014

By Adel Heenan

About this summary brief

The purpose of this document 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 monitoring program known as the Pacific Reef Assessment and Monitoring Program (Pacific RAMP). More detailed survey results will be available in a forthcoming annual status report.

Sampling effort

  • Ecological monitoring took place in the Pacific Remote Island Areas from March 16 2014 to March20 2014.
  • Data were collected at 45 sites. Surveys were conducted at Wake Island.
  • 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.

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).

 

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 (Fig. 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 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.

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.

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

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

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 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: http://coralreef.noaa.gov

Pacific Islands Fisheries Science Center: http://www.pifsc.noaa.gov/

CRED publications: http://www.pifsc.noaa.gov/pubs/credpub.php

CRED fish team: http://www.pifsc.noaa.gov/cred/fish.php

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

 

 

Researchers survey a high-priority coral reef area off Maui

By John Rooney
R/V AHI. NOAA photo

R/V AHI. NOAA photo

A team of scientists from the Coral Reef Ecosystem Division (CRED) of the NOAA Pacific Islands Fisheries Science Center on Tuesday began a mission to conduct acoustic and optical surveys of the waters of coral reef ecosystems in Maui. The team shipped their 8-m survey launch R/V AHI, equipped with a diesel generator to provide power and a Reson 8101ER multibeam echosounder, to Maui from O’ahu last week to support this survey effort.

Optical surveying will focus on one of two high-priority coral reef sites in Hawai’i identified by the Hawai’i Department of Land and Natural Resources (DLNR) and NOAA’s Coral Reef Conservation Program (CRCP): an area near Kahekili off West Maui (see map below at left). In 2013, the U.S. Geological Survey (USGS) conducted shallow-water mapping in the area, generally at depths of 10–40 m. The present survey effort on Feb. 4–21 will collect video and still photographs of the seafloor at depths of 30–100 m to overlap with and extend the USGS maps out to the 3-mile boundary of state waters or to a depth of ~100 m.

The red box in this map indicates the survey area where the camera sled will be deployed. This area off Kahekili, Maui, has been designated by the Hawai’i Department of Land and Natural Resources and NOAA’s Coral Reef Conservation Program as one of two high-priority sites in the state.

The red box in this map indicates the survey area where the camera sled will be deployed. This area off Kahekili, Maui, has been designated by the Hawai’i Department of Land and Natural Resources and NOAA’s Coral Reef Conservation Program as one of two high-priority sites in the state (click image for a larger version).

For the surveys, members of the CRED ecospatial information team will use an underwater camera sled, called the “TOAD,” for towed optical assessment device (see photo below at right). The data collected during these TOAD surveys will enable the team to map the dominant seafloor structures (e.g., pavement, patch reef, and sand) and the major classes of biologic cover (e.g., coral and macroalgae) in the area. The extended maps will provide DLNR and other management agencies and coastal and marine stakeholders with the spatial data needed to make informed decisions about the management of nearshore marine resources and habitats.

The second goal of this survey mission is to fill gaps in existing maps that depict seafloor depths, or bathymetry, with a high degree of detail. No type of seafloor map is of higher value to more people than are maps of high-resolution bathymetry. However, gaps in existing maps (see map below) inhibit their use for many purposes.

To collect data to fill some of those gaps, the survey team will operate the multibeam echosounder on the R/V AHI. They’ll first fill remaining gaps in the data for the Kahekili high-priority site, and then they will spend the remaining time surveying in the most windward and exposed sites in which they are able to operate.

The video and still photographs collected by the towed optical assessment device (TOAD), the camera sled shown being deployed from a ship in this photo, can be analyzed to help map the character of benthic habitats. NOAA photo

The video and still photographs collected by the towed optical assessment device (TOAD), the camera sled shown being deployed from a ship in this photo, can be analyzed to help map the character of benthic habitats. NOAA photo

After the mission, the team will clean and process the data and then provide them to NOAA’s National Geophysical Data Center to be made publicly available for download. The data also will be provided to the School of Ocean and Earth Science and Technology (SOEST) at the University of Hawai’i at Mānoa for inclusion in the synthesis of high-resolution bathymetry data that SOEST has maintained for many years.

Funding for this project was provided by the CRCP. We thank the Hawai’i DLNR for graciously providing logistical support and the USGS for going out of their way to send us copies of their existing data and publications.

Follow this link for a PDF version of this story about the latest mapping surveys off Maui.

For more information about this mission and CRED benthic habitat mapping, contact John Rooney, program manager for the ecospatial information team, at john.rooney@noaa.gov.
This map shows existing high-resolution bathymetry collected around Maui, color coded by depth and superimposed over a nautical chart.

This map shows existing high-resolution bathymetry collected around Maui, color coded by depth and superimposed over a nautical chart.

The final count: cruise for monitoring of effects of ocean and climate change in the Northwestern Hawaiian Islands completed

By Chip Young

Scientists from the PIFSC Coral Reef Ecosystem Division (CRED) recently completed a 17-day expedition to the Northwestern Hawaiian Islands, where they conducted coral reef monitoring surveys at Pearl and Hermes Atoll, Lisianski Island, and French Frigate Shoals. These 3 locations are part of the Papahānaumokuākea Marine National Monument and World Heritage Site, the third largest marine protected area on Earth and the largest conservation area in the United States.

This PIFSC research cruise (HA-13-05) aboard the NOAA Ship Hi`ialakai implemented a standardized set of methods for the measurement of fluctuations in the region’s coral reef ecosystems caused by global climate change. NOAA’s National Coral Reef Monitoring Plan (NCRMP) outlines the importance of monitoring changes in temperature and the chemical composition of ocean waters within which the coral reef ecosystems of the United States are found. Coral reefs are fragile biological systems that have been observed to live best in specific ranges of water temperatures and composition parameters. Changes in either of these ranges can cause a coral reef system to malfunction, through problematic processes that are familiar to much of the general public. Such processes, including coral bleaching (a result of increased ocean temperatures) and ocean acidification (a result of a drop in the ocean’s pH), affect the ability of corals and other reef organisms to calcify or “build their houses.” Other potential effects can occur, as well, such as shifts in biogeochemical cycles, shifts in species diversity, and changes in the ocean’s food web.

Jamison Gove and Chip Young of the PIFSC Coral Reef Ecosystem Division deploy oceanographic instrumentation on Sept. 13 at Lisianski Island as part of the recent research cruise to the Northwestern Hawaiian Islands. NOAA photo by Oliver Vetter

Jamison Gove and Chip Young of the PIFSC Coral Reef Ecosystem Division deploy oceanographic instrumentation on Sept. 13 at Lisianski Island as part of the recent research cruise to the Northwestern Hawaiian Islands. NOAA photo by Oliver Vetter

As part of the implementation of the NCRMP, CRED scientists on Sept. 3–19 deployed 16 arrays of temperature sensors along various reef systems, installing a total of 64 instruments at depths of 1–25 m. At its specific location on a reef, each sensor records the seawater temperature at the same time as other sensors, every 5 min, over a period of 3 years. The resulting product is a high-resolution picture of temperature variability of 16 different reef systems across space (across the archipelago and to a depth of 25 m) and time (3-year deployment of each sensor).

During the monitoring cruise earlier this month, 100 calcification accretion units (CAUs), like the one shown above, were installed in the Northwestern Hawaiian Islands by staff of the PIFSC Coral Reef Ecosystem Division. CAUs are used to measure not only net reef calcification rates but also species-specific recruitment rates and the percent cover of corals, crustose coralline algae, and fleshy algae. NOAA photo

During the monitoring cruise earlier this month, 100 calcification accretion units (CAUs), like the one shown above, were installed in the Northwestern Hawaiian Islands by staff of the PIFSC Coral Reef Ecosystem Division. CAUs are used to measure not only net reef calcification rates but also species-specific recruitment rates and the percent cover of corals, crustose coralline algae, and fleshy algae. NOAA photo

CRED scientists and partners also collected samples of seawater for chemical analysis, conducted hydrocasts with a conductivity-temperature-depth (CTD) instrument, and deployed installations designed to measure specific biological activities that can be affected by changes in the pH of a reef’s waters. Settling plates, known as calcification accretion units (CAUs), are used to measure net reef calcification rates, species-specific recruitment rates, and the percent cover of corals, crustose coralline algae, and fleshy algae. Bioerosion monitoring units (BMUs) are made up of precisely measured pieces of calcium carbonate, the material that makes up the skeletal structure of corals, and will provide a value for how much biological removal of reef structure is naturally present along the reef. Autonomous reef monitoring structures (ARMS) essentially act as “hotels” for cryptic biota living within the matrix of a reef ecosystem and provide a standard method for evaluation of the existing community of sessile and mobile organisms found on a reef.

Including work conducted during this cruise and the earlier PIFSC cruise SE-13-05 to Kure Atoll in July, CRED scientists have installed 100 CAUs, 50 BMUs, and 24 ARMS throughout the Northwestern Hawaiian Islands this year. Because monitoring activities associated with NCRMP are conducted on a triennial basis, CRED will return to these islands in 2016. At that time, researchers will retrieve and replace all instruments. NCRMP is a long-term project, and the goal of this work is to measure change over time. The results from this ongoing project will be available to help the managers of these remote islands monitor, evaluate, and predict the ecological effects of global climate change on the reefs of the Papahānaumokuākea Marine National Monument.

Update from Timor-Leste: scientists complete live-aboard mission to survey reef fishes and benthos, assess ocean acidification

By Andrew Gray

Scientists from the PIFSC Coral Reef Ecosystem (CRED) recently finished a 2-week live-aboard expedition to survey reef fish and benthic communities, collect water samples, and record data on seafloor depths along the northern coast of Timor-Leste. This mission was part of a larger operation that also included similar monitoring work based from land, capacity-building activities, and an outreach effort. Our last blog post from Timor-Leste left off with our boarding of the catamaran Sundancer NT on June 13 to start the live-aboard mission.

Brett Schumacher of the PIFSC Coral Reef Ecosystem Division surfaces behind the live-aboard vessel Sundancer NT on June 19 after conducting a survey of reef fishes and taking photos of benthic communities during a 2-week live-aboard mission off the northern coast of Timor-Leste. NOAA photo

Brett Schumacher of the PIFSC Coral Reef Ecosystem Division surfaces behind the live-aboard vessel Sundancer NT on June 19 after conducting a survey of reef fishes and taking photos of benthic communities during a 2-week live-aboard mission off the northern coast of Timor-Leste. NOAA photo

We arrived at the Sundancer NT in Dili Harbor before lunch on June 13 after traveling in a pair of pickup trucks for 1.5 hours on narrow, winding roads from Caimeo Beach in Liquiçá, where we had ended our land-based survey work. Why switch to a boat-based mission? The beauty of a live-aboard situation is that it eliminates time spent on transfers between your base on land and survey sites. During our live-aboard mission, long distances between survey sites were covered at night as everyone slept and we arrived at our survey sites at first light. With the catamaran as our base, remote locations that could have been difficult or impossible to survey during a land-based setup—locations such as Oecussi, an enclave of Timor-Leste within Indonesia, and the dramatic, cliff-flanked jungle coast of the Lautem district—were as easy to access as Dili Harbor.

The first day of live-aboard operations began with a safety drill to assess our ability to rescue divers in distress. Max Sudnovsky of CRED and I put on our dive gear, and Sudnovsky feigned an unconscious diver ~90 m off the stern of the Sundancer NT. True to their training, the team had us both onboard and Sudnovsky stabilized and breathing oxygen within 5 min of starting the drill. We made a few tweaks to our setup—adding a pair of throw lines and staging the oxygen in the pilot house—to decrease our response time. With the drill done, we began our first operational dive of the mission, starting with collection of a water sample for analysis of dissolved inorganic carbon at one of the permanent monitoring sites set up in October by researchers during a previous CRED mission.

For the rest of that day and over the next 12 days, we leapfrogged down the coast to complete surveys with 2 dive teams—1 on the Sundancer NT and 1 on a tender boat—at sites in Oecussi, off Atuaro Island, and along the length of the northern coast of Timor-Leste from Bobonaro to the eastern tip of Jaco Island in the Lautem district. We completed our assessment activities at as many as 10 sites per day.

Kaylyn McCoy of the PIFSC Coral Reef Ecosystem Division, on the first day of the live-aboard mission on June 13, gives the OK signal before she hops off a swim step of the Sundancer NT and into the ocean to conduct a stationary-point-count survey of reef fishes off the northern coast of Timor-Leste. NOAA photo

Kaylyn McCoy of the PIFSC Coral Reef Ecosystem Division gives the OK signal before she hops off the Sundancer NT and into the ocean on June 13 to conduct a stationary-point-count survey of reef fishes off the northern coast of Timor-Leste. NOAA photo

Aboard the tender boat piloted by Ian Brown, Brett Schumacher and Kaylyn McCoy of the PIFSC Coral Reef Ecosystem Division return to the Sundancer NT after completing surveys of reef fish and benthic communities and recording depth soundings on June 16 off the northern coast of Timor-Leste. NOAA photo

Aboard the tender boat piloted by Ian Brown, Brett Schumacher and Kaylyn McCoy of PIFSC return to the Sundancer NT after completing surveys and recording depth soundings off Timor-Leste on June 16. NOAA photo

The Sundancer NT, an aluminum catamaran (15.0 x 7.9 m) that was chartered through Compass Charters, served well during our mission. Two swim steps, one on the stern of each hull, were great entry and exit points for our dives. The vessel’s shallow draft and the expert driving of its captain, Peter Herdew, allowed us to get directly over any dive site. A tender boat served as a second dive platform, capable of holding 2 divers with scuba cylinders and the seafloor mapping tool. The mapping tool was used to opportunistically collect depth soundings to derive WorldView-2 satellite-derived depths and create accurate shallow-water bathymetry for the area, something Timor-Leste lacks at the moment. The tool consists of a transducer, processor, high-accuracy GPS unit, and a handheld computer that wirelessly receives and records data.

Regardless of the location of our first survey on a given day, by 7:30 a.m., when there was sufficient light for our visual surveys, we had already eaten breakfast, completed our safety brief and assembled our dive gear and the first team was ready to roll into the water. Typically, we wrapped up surveys by 5 p.m., leaving time to rinse and put away gear and enter the day’s data before a dinner at 8 p.m. After dinner, the team took turns reading off data entered into the database to assure quality and then headed to our bunks for the night as the Sundancer NT transited to the next survey site.

As Paula Ayotte, Kevin Lino, Kaylyn McCoy, Brett Schumacher, and I conducted surveys and collected water samples from the Sundancer NT, Sudnovsky, who was the project coordinator for this mission, and Rui Pinto, who was an invaluable local contact and master logistician from the Coral Triangle Support Partnership (CTSP), followed us by land along the northern coast. Sudnovsky and Pinto visited each district prior to our arrival by sea to inform the communities about our presence in the area, the data we were collecting, and how that data can benefit them and the country of Timor-Leste. They also did an outstanding job of working with local fisheries officers, fishermen, and NGOs to raise community awareness of ocean acidification and today’s changing ocean as well as awareness of the need for local management of Timor-Leste’s nearshore reef fisheries and simple steps that can be taken to help protect local fisheries. Intermittently, Sudnovsky provided help aboard the Sundancer NT, in addition to his participation in the safety drill on the first day of the live-aboard mission. Pinto and Sudnovsky provided a banner (1 x 3 m) for the catamaran that read, “Levantamentu dadu kona-ba biomasa ikan iha Timor-Leste nia tasi-feto,” and included the insignia of all cooperating agencies: NOAA, U.S. Agency for International Development, Conservation International, CTSP, and the Democratic Republic of Timor-Leste. This banner text translates to “Fish biomass surveys in Timor-Leste’s female sea.” The female sea is the sea to the north of the country, and the male sea is to the south.

Besides the out-of-season squalls and high winds (and subsequent wind swell) that we encountered on the second half of this mission, our biggest challenge was finding locations with the proper substrate and visibility to conduct surveys. The stationary-point-count survey method requires only reasonable visibility (~8 m) and a hard bottom at survey depths. In some areas of the Manatutu district, a number of rivers create silty bottoms and zero visibility, and we had to transit long distances between surveys.

A red lionfish (Pterois volitans) sits motionless above corals of the genus Acropora on a Timor-Leste reef on June 16. NOAA photo

A red lionfish (Pterois volitans) hovers motionless above corals of the genus Acropora on a reef off the northern coast of Timor-Leste on June 16. NOAA photo

Despite such challenges, during the live-aboard mission on June 13–27, our team completed 92 surveys throughout the 7 northern districts of Timor-Leste, reaching our goal of surveys conducted at 150 sites over our entire operation at Timor-Leste last month. We identified 456 species of fishes from 52 families during our surveys. Observed species included the humphead wrasse (Cheilinus undulatus), which is nationally protected in Timor-Leste and listed as endangered on the IUCN Red List of Threatened Species, and bumphead parrotfish (Bolbometopon muricatum), which is listed as vulnerable on the IUCN Red List of Threatened Species. We even had 2 underwater encounters with the elusive dugong (Dugong dugon), a large mammal that is in the same order as manatees. Although we have yet to analyze the data we collected, our general impression was that, in addition to the high diversity of the areas that we surveyed, there was a general abundance of small- to medium-bodied food fishes on reefs at the depths surveyed (≤18 m) with occasional larger individuals.

We thank Captain Herdew and the Sundancer NT crew (Ian Brown, Kym Miller, and Kim Hamilton) for helping us achieve our goal of 150 sites surveyed. This expedition to collect baseline data on reef fishes and benthos for the government of Timor-Leste and NOAA has been a rewarding experience, and we are all looking forward to the results of our analyses of these survey data. Check in again at this space to hear from team lead Kevin Lino, who will provide a mission summary.

Kevin Lino of the PIFSC Coral Reef Ecosystem Division on June 16 reels out a transect line before he conducts a stationary-point-count survey of reef fishes off the northern coast of Timor-Leste. NOAA photo

Kevin Lino of the PIFSC Coral Reef Ecosystem Division on June 16 reels out a transect line before he conducts a stationary-point-count survey of reef fishes off the northern coast of Timor-Leste. NOAA photo