What happens to reef fish after coral bleaching?

by Adel Heenan

For the past month, researchers aboard the NOAA Ship Hi‘ialakai have been navigating across the Pacific Ocean to survey coral reef ecosystems at remote Wake Atoll and the Mariana Archipelago. This expedition includes additional surveys at Jarvis Island, in the Pacific Remote Islands Marine National Monument, to assess the reef condition and degree of recovery from a catastrophic coral bleaching event in 2014-2015.


Jarvis Island is located in the central Pacific Ocean, close to the equator, and is a small island in the direct path of a deep current that flows east (Figure 1). Because of it’s position right on the equator and the strong currents hitting the island, Jarvis sits in the middle of a major upwelling zone—where cold nutrient rich water is drawn up from the deep. This water fertilizes the whole area, elevating nutrient levels and productivity in the reef ecosystem (Gove et al., 2006). As a result, Jarvis supports exceptionally high biomass of planktivorous and piscivorous fishes (Williams et al., 2015).

Because it is unpopulated and extremely remote, Jarvis provides an important reference point and opportunity to understand the natural structure, function, and variation in coral reef ecosystems. The island also offers a natural laboratory in which the effects of ocean warming can be assessed in the absence of stressors that impact coral reefs where humans are present (e.g., fishing or land-based sources of pollution).

El Niño, La Niña and the global coral bleaching event of 2014-2015
The Equatorial Pacific upwelling at Jarvis alternates between warm El Niño years, when upwelling is weak and oceanic productivity low, and cold La Niña years where upwelling is strong and productivity is high (Gove et al., 2006). Unusually warm sea surface temperatures, and a strong El Niño in 2014-2015, triggered the third recorded global coral bleaching event. At Jarvis, these warmer waters led to widespread coral bleaching and mortality. High sea surface temperatures in 2015 also impacted upwelling at Jarvis, as evidenced by a decrease in the primary productivity around the island.

Teams from the Coral Reef Ecosystem Program recently completed ecological monitoring at Jarvis from April 2–5, 2017. They collected data at 28 stationary point count sites (Figure 2) this year, 30 in 2016, 62 in 2015, 42 in 2012, and 30 in 2010.

FIG2_SPC

Figure 2. The stationary point count method is used to monitor the fish assemblage and benthic communities at the Rapid Ecological Assessment (REA) sites.

Main Observations
Fish biomass tended to be highest on the western side of the island where equatorial upwelling occurs (Figure 3). In 2016, we observed somewhat reduced total fish and total planktivore biomass (Figure 4), but this reduction was within the normal range of observed variability.

There were some significant reductions observed for individual species in 2016. These reductions were noticeable across multiple trophic groups, for instance the planktivorous Whitley’s fusilier (Luzonichthys whitleyi), Olive anthias (Pseudanthias olivaceus), Dark-banded fusilier (Pterocaesio tile), the piscivorous Island trevally (Carangoides orthogrammus), and the coral-dwelling Arc-eyed hawkfish (Paracirrhites arcatus) which is strongly associated with Pocillopora coral heads. Some of these species had returned to previous ranges by 2017, but others remain depleted (Figure 5).

FIG5_FishBiomass

Figure 5. Mean species biomass (± standard error) per survey year at Jarvis.

Very high levels of coral mortality were evident in 2016 surveys and coral cover remained low in 2017. Notably, macroalgal cover increased in 2017, approximately by the amount of coral cover lost in 2016 (Figure 6).

FIG6_PercentCover

Figure 6. Mean percentage cover estimates (± standard error) of benthic habitat per survey year at Jarvis. Data shown for Hard Coral (top, red); macrolagae (middle, green) and CCA: crustose coralline algae (bottom, orange). Note: no benthic data are available for 2008 as we began collected rapid visual estimates of these benthic functional groups in 2010.

Whether this reduction in specific planktivore, piscivore, and live coral-dwelling fish species is a widespread and long-standing shift in the fish assemblages at Jarvis will be the subject of forthcoming research. It seems plausible that they reflect impacts of a prolonged period of reduced food availability and changes to preferred habitat due to the anomalous warm sea conditions in 2014–2015. Our teams will return to Jarvis in 2018 to conduct another assessment in an attempt to answer some of these questions.

FIG7_shark

An emaciated grey reef shark (Carcharhinus amblyrhynchus) observed during a 2017 fish survey. (Photo: NOAA Fisheries/Adel Heenan)

Additional detail on survey methods and sampling design are available in the full monitoring brief: Jarvis Island time trends 2008-2017.

References
Gove J. et al. (2006) Temporal variability of current-driven upwelling at Jarvis Island. J Geo Res: Oceans 111, 1-10, doi: 10.1029/2005JC003161.
Williams I. et al. (2015) Human, oceanographic and habitat drivers of central and western Pacific coral reef fish assemblages. PLoS 10: e0120516, doi: 10.1371/journal.pone.0120516.

 

Creating a “Community” for the Pacific Remote Islands Marine National Monument

by Hoku Johnson

How do managers effectively spread the word about the natural splendors of a large, extremely remote place?  Who is the “community” of people that will provide advice to NOAA and U.S. Fish and Wildlife Service managers on development of a management plan for this place?  Why should anyone care about the Pacific Remote Islands Marine National Monument (PRIMNM)?

Wading toward the small boats after a day of manager-expert discussions.

Wading toward the small boats after a day of manager-expert discussions.

Sean Russell, Susan White, Callum Roberts and Leanne Fernandes discuss marine conservation while wading through the water at Palmyra Atoll.

Sean Russell, Susan White, Callum Roberts and Leanne Fernandes discuss marine conservation while wading through the water at Palmyra Atoll.

Last week, a small group of four experts and four marine managers set out to discuss these questions on Palmyra Atoll, a National Wildlife Refuge located within the PRIMNM, approximately 1,100 miles south of Honolulu.  Their main task: develop a community steering committee comprised of stakeholders that will be able to provide advice to managers on everything ranging from prioritizing research to figuring out creative ways to bring the wonders of these remote protected atolls and islands to the world.

Before diving into discussion, the group had the opportunity to dive into the ocean surrounding Palmyra Atoll to connect with the place and experience a kaleidoscope of corals, fishes, sharks, and turtles. The diving and snorkeling was amazing and reminded the group of why a community of advocates is important to such a remote area.

The group discusses building a community steering committee for the Pacific Remote Islands Marine National Monument.

The group discusses building a community steering committee for the Pacific Remote Islands Marine National Monument.

Once everyone dried off, the group–consisting of Dr. Callum Roberts, Dr. Leanne Fernandes, Mr. Sean Russell, Ms. Hoku Johnson, Mr. Matthew Brown, Ms. Samantha Brooke, Ms. Heidi Hirsh, Ms. Susan White, and facilitator Ms. Deanna Spooner–delved into topics including: sorting through relevant stakeholder groups, discussing the Presidential Proclamations that established and expanded PRIMNM, different ways a community steering committee might be convened, and priority topics this group would discuss in the future.

Juvenile coconut crab

Juvenile coconut crab

By the end of the week, the group finalized a draft framework for a community steering committee (dubbed the “PRIMNM CSC”) that will be fleshed out further by the NOAA and Fish and Wildlife Service managers over the next few months. The group celebrated their achievement by participating in a Palmyra Atoll Research Consortium beach barbecue and an evening “crab walk” looking for numerous species of crabs that live on Palmyra Atoll.

Refuge Manager Stefan Kropidlowski talks with the group about the native Pisonia tree behind him.

Refuge Manager Stefan Kropidlowski talks with the group about the native Pisonia tree behind him.

Visit to Johnston Atoll Wildlife Refuge: PIFSC SE-13-07 “Deep -7” Bottomfish research expedition blog

We visited Johnston Atoll today via small boat launches from the NOAA Ship Oscar Elton Sette. The story of the atoll is long and varied and it has had multiple uses throughout its history. At the end of WWII Johnston Atoll was designated a site for one of the United States’ nuclear testing programs. Up until 1962, high-altitude nuclear testing was carried out at Johnston Atoll. Johnston Atoll was also a site for stockpiling chemical weapons which were incinerated in the Johnston Atoll Chemical Agent Disposal System which was decommissioned in 2004. Almost all of Johnston Island’s infrastructure had been removed by 2005, and all personnel left the atoll, including refuge staff.

See these external sites for more information about Johnston Atoll:
http://www.fws.gov/johnstonisland/
http://www.doi.gov/oia/islands/johnston.cfm
http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Johnston_Atoll.html
http://www.cma.army.mil/johnston.aspx

On approach to Johnston Atoll.  In the background is one of the leftover buildings from when this was a bustling US military base

On approach to Johnston Atoll. In the background is one of the leftover buildings from when this was a bustling US military base

One of the most amazing sites as you approach the island is the amazing coral reefs surrounding the island. There are numerous species of coral at Johnston Atoll with the most conspicuous species being the giant table coral (Acropora cytherea). See previous bottomfish research expedition post: http://bit.ly/16lqv6R

The 5 U.S. Fish & Wildlife Service (USFWS) staff were very happy to receive us and to accept our gifts of fresh produce. The USFWS staff were very hospitable and upon our arrival provided everyone with homemade leis.

The U.S. Fish and Wildlife Service staff presenting us with homemade leis

The U.S. Fish and Wildlife Service staff presenting us with homemade leis

Preparing for a tour of the island

Preparing for a tour of the island

The USFWS staff gave us a tour of the island and showed us some of the more interesting aspects of the atoll. They also offered us bikes to use for riding around the island. This short respite was very welcome and it felt great to step on dry land and stretch the legs. The atoll has an interesting mix of natural and manmade curiosities as you tour around. One of the first things you notice is the large colonies of birds, which is to be expected as Johnston Atoll National Wildlife Refuge manages 14 species of breeding sea birds and 5 species of wintering shorebirds see external link: http://www.fws.gov/refuges/profiles/index.cfm?id=12515 for more details.

The yellow crazy ants (Anoplolepis gracilipes) super-colonies had us all intrigued. These ants spray formic acid into the eyes of their prey, and then while the animal is blind overcome it with numbers. We were warned about these prior to our visit and had to take measure to ensure we did not take any hitchhikers back with us. Presently the USFWS has a group on the island eradicating this menace and hopefully this will be accomplished soon.

See external links for more information on the yellow crazy ants: (http://news.bbc.co.uk/2/hi/asia-pacific/2807289.stm; http://www.ncbi.nlm.nih.gov/pubmed/21396065)

The island is dotted with ironwood and palm trees planted by the previous inhabitants interspersed with remnant cement foundations that all are indicators of the previous incarnation of the island as a busy military base.

The crew and scientists were back aboard NOAA Ship Oscar Elton Sette by 1930h and the ship began its transit back to Ford Island, Honolulu.

Shark Encounters: PIFSC SE-13-07 “Deep -7” Bottomfish research expedition blog

Shark interactions

When we first arrived in the Pacific Remote Islands Marine National Monument waters off Johnston Atoll we started plotting bottomfish sampling locations using topography, currents and the EK-60 fish finder to identify areas of interest. However this was altered during the field work because we encountered a lot of sharks during our fishing efforts. We later decided to target depth features with less fish abundance so we would have a higher probability of obtaining our samples without shark interference. See previous bottomfish research expedition post: http://bit.ly/17RGrdg

Submerged Go-Pro shots of sharks believed to be Galapagos.  Photo taken from NOAA Ship Oscar Elton Sette in waters around Johnston Atoll gave evidence of the increased shark numbers interacting with our bottomfish sampling.

Submerged Go-Pro shots of sharks believed to be Galapagos. Photo taken from NOAA Ship Oscar Elton Sette in waters around Johnston Atoll gave evidence of the increased shark numbers interacting with our bottomfish sampling.

The sharks appeared to be Galapagos sharks based on surface sightings and “Go-Pro” camera video shots taken underwater from a submerged pole over the NOAA Ship Oscar Elton Sette’s side. Once we are back in Honolulu we will upload the videos to this blog for your viewing. We have some amazing footage that provided a huge surprise on the actual number of sharks present under the boat. One video showed at least 15 sharks circling at one time.

During one day of bottomfish sampling from the NOAA Ship Oscar Elton Sette we were operating on a one drop per station method. Typically we could get one drop down and recover fish but on the second drop the sharks were ready for us and either attacked our fishing line deep during retrieval or at/near the surface. Three Galapagos sharks completely devoured a hapu’upu’u that we brought to the surface; excellent “Go-Pro” video was taken of this event. The small boats were also plagued by shark activities.

Hapu'upu'u dinner!  This is a still shot from a video Justin Kantor shot of three Galapagos sharks completely devouring one of our samples.  Obviously the hapu'upu'u's facial features say it all.

Hapu’upu’u dinner! This is a still shot from a video Justin Kantor shot of three Galapagos sharks completely devouring one of our samples. Obviously the hapu’upu’u’s facial features say it all.

Galapagos sharks fight over the remains of the hapu'upu'u

Galapagos sharks fight over the remains of the hapu’upu’u

Shark avoidance maneuver on the small boats

What the?  Eddie Ebisui III is not too happy with the percentage of "taxes" the Galapagos sharks ("the taxman") are taking.  The sharks bite the entire bodes clean off.

What the? Eddie Ebisui III is not too happy with the percentage of “taxes” the Galapagos sharks (“the taxman”) are taking. The sharks bite the entire bodes clean off.

The small boat crew also had their hands full with the over-exuberant sharks. To avoid the problem of losing parts or all of the fish to the sharks, the small boat crew came up with a “shark avoidance maneuver”. Jamie Barlow explained that once sharks were spotted while reeling in a desirable bottomfish (determined by how the line feels during the bite), the small boat would have to maneuver to avoid loss of the sample. This could be accomplished either by speeding away with a high probability of losing the sample (fish busting the leader or tearing away) or going slow and losing the sample to the shark. To avoid either of these undesirable outcomes they considered several factors when determining actions to be taken on the small boat for saving the fish.

Every situation was different and the coxswain had to mitigate the risks and factor in these variables:

1. What is the load (weight) on the rod and reel (how big, how many)

2. Consideration of running the small boat down seas so the rod does not jerk the fish and release itself from the hole the hook would make in the fish’s jaw.

3. Be aware of the location of the sun glare (reflection of the sun off the water) and finish the maneuver so the small boat crew can see the sharks for the last critical 30 seconds of recovery

4. Consider heading to deeper waters where typically there was less shark abundance

5. How aggressive are the sharks?

6. Pull the line with the fish rapidly and safely into the boat without inviting the shark into boat as well

7. Whoever is pulling the line is experienced enough so that if the shark does grab the fish, they will hold that line firmly to bust the leader and prevent gear and hooks to be pulled backward by the powerful fish.

While calculating these variables, Jamie Barlow would conduct this maneuver as a spiraling left turn. Varying angles and speeds were balanced while being mindful of keeping the line away from the prop and bringing the fish coming out at an angle and a speed that prevents the shark from grabbing the fish. This was a tricky maneuver, but it worked for about 3-5 times, after which, the sharks wised up. The sharks had watched enough fish scoot passed them to learn that a bold burst of ambush speed would reward the natural predator with a tasty opakapaka or onaga. And once they got that bold the fishermen would have to tuck their tails between their legs and run a mile to a new spot and start the “small boat shark maneuver” all over again. See next bottomfish research expedition post: http://bit.ly/15VFlU8

In search of the elusive bottomfish: PIFSC SE-13-07 “Deep -7” Bottomfish research expedition blog

Searching out Deep-7 bottomfish

Extensive effort was required to collect a minimum of 30, and maximum of 50, fin-clip tissue samples from bottomfish in the Johnston Atoll area to conduct DNA analyses. Proposing the collection of 30 fin clips is very different from actually obtaining them, especially in an area where very little is known about bottomfish behavior. See previous bottomfish research expedition post: http://bit.ly/1cI479t

Bottomfish sampling team from left to right Meagan Sundberg, Jamie Barlow, Mills Dunlap, Eddie Ebisui III

Bottomfish sampling team from left to right Meagan Sundberg, Jamie Barlow, Mills Dunlap, Eddie Ebisui III

Our bottom fishing expert, Eddie Ebisui III and our Chief Scientist Bob Humphreys were tasked with providing the best spots for collecting the samples. The night before fishing, they would look at the weather for the following day to determine the area most conducive for fishing and away from bad weather. By deciding the night before it allowed the time for the ship to transit through the night to the desired location for scouting.

Once over the desired location, a course would be plotted for the ship to take that covers the targeted depth ranges of the Deep-7 bottomfish species we were seeking. The ship will survey for topography, currents and use an EK-60 fish finder to identify areas of interest. The depth ranges were determined from knowledge we had from Hawaiian waters and also by continually adapting our fishing according to our catch data in the Johnston Atoll waters of the Pacific Remote Islands Marine National Monument. Certain species look for bottom structure and also specific current speeds and direction. For example, hapu’upu’u live in a depth range of 100-130 fathoms and since they are ambush feeders, they like rocky structures with caves and crevices to help them to eat. They are solitary and are spread out over larger spatial areas so requires continuous moving to catch them. gindai and yellowtail kalekale are found over the entire depth range while onaga were typically found around 120-140 fathoms and had the narrowest depth band of each of the Deep-7 species. Once locations were identified they were marked and the GPS coordinates were passed onto the small boats

The depth distribution of the bottomfish seemed shifted toward deeper depths at Johnston Atoll compared to the Main Hawaiian Islands. Louise Giuseffi plotted depth ranges for 8 bottomfish species that included the almaco jack (Seriola riviolani), black ulua, ehu gindai, hapu’upu’u, lehi, onaga, and opakapaka and all had similar deep distributions between 115-140 fathoms. The most abundant species that appeared at all depths was the yellowtail kalekale while the two principal species of jacks encountered (Carangoides orthogrammus and Caranx lugubris) were encountered at the shallower depth from 85-110 fathoms. The bottomfish habitat at Johnston Atoll is likely highly influenced by the steep topography of the bottom.

Our efforts resulted in a cumulative number of fin clip samples obtained for the snapper/grouper complex:

Our efforts resulted in a cumulative number of fin clip samples obtained for the snapper/grouper complex:

Our efforts resulted in a cumulative number of fin clip samples obtained for the snapper/grouper complex:

Eddie Ebisui III and Jamie  Barlow displaying the catch of the day.  While catch and release was the primary goal fish had to be kept when shark interactions occurred.

Eddie Ebisui III and Jamie Barlow displaying the catch of the day. While catch and release was the primary goal fish had to be kept when shark interactions occurred.

We have now achieved our minimum sample sizes (n=30) for 5 species (onaga, opakapaka, hapu’upu’u, gindai, and yellowtail kalekale) and optimum sample size (n=50) for opakapaka, gindai, and yellowtail kalekale.

Scientists and crew on the NOAA Ship Oscar Elton Sette preparing for the days operations.  From front to back: Tommy Knowles, Ray Storms, Stephanie Koes (The Commanding Officer of the Oscar Elton Sette), Eric Mooney, Eric Breuer, and Justin Kantor.

Scientists and crew on the NOAA Ship Oscar Elton Sette preparing for the days operations. From front to back: Tommy Knowles, Ray Storms, Stephanie Koes (The Commanding Officer of the Oscar Elton Sette), Eric Mooney, Eric Breuer, and Justin Kantor.

Leaving Johnston Atoll waters: PIFSC SE-13-07 “Deep -7” Bottomfish research expedition blog

Sunset during the last night of sampling

Sunset during the last night of sampling

Aloha to the Pacific Remote Island Marine National Monument waters of Johnston Atoll. The sampling objectives have been accomplished and the scientists and crew onboard the NOAA Ship Oscar Elton Sette and are heading home. The bird colony (comprised mainly of Boobies) from Johnston Atoll Wildlife refuge provided frequent companions for us and have provided a running commentary on our sampling techniques.

Juvenile and adult Boobies have been our constant companions and source of entertainment during our research

Juvenile and adult Boobies have been our constant companions and source of entertainment during our research

The Chief Scientist, Bob Humphreys, along with a host of seabirds watch Robert Spina closely as he samples for bottomfish

The Chief Scientist, Bob Humphreys, along with a host of seabirds watch Robert Spina closely as he samples for bottomfish

Here Louise "the Falconer" Giuseffi gets quite the surprise while bringing in the sampling gear

Here Louise “the Falconer” Giuseffi gets quite the surprise while bringing in the sampling gear

The sampling efforts included:
• collecting enough fin-clip tissue samples from bottomfish in this area for DNA analyses
• capturing pelagic stage specimens of the bottomfish inhabiting this area
• conducting ocean measurements to characterize the physical environment that pelagic stage bottomfish may be associated with.

These samples, once analyzed, may lead to a better understanding of the environmental habitat of the bottomfish under investigation (these bottomfish species include the Hawaiian grouper “hapu’upu’u” and six species of deep-water snappers (“opakapaka”, “ehu”, “onaga”, “lehi”, “gindai”, and “kalekale”) and provide an understanding of the extent that populations between Johnston Atoll and the Hawaiian Archipelago are interconnected.

Small boat crew finishing up sampling operations prior to departure.  The Henry Ching reel seen attached to the front right of the boat is operated using a 12volt battery and allows for sampling at over 1000 ft depth.

Small boat crew finishing up sampling operations prior to departure. The Henry Ching reel seen attached to the front right of the boat is operated using a 12volt battery and allows for sampling at over 1000 ft depth.

As the ship makes the journey back toward Oahu it will be stopping every night to continue collecting temperature, salinity, and dissolved oxygen chlorophyll measurements within the water column and pelagic stage specimens of the bottomfish being investigated. These samples will be collected using the same methods employed in the waters off Johnston Atoll. See previous bottomfish research expedition post for more information: http://bit.ly/1cGVagv

The CTD Rosette, nicknamed "Rosy", sitting on the deck waiting for action

The CTD Rosette, nicknamed “Rosy”, sitting on the deck waiting for action

CTD and chlorophyll samples

Some of the major factors that play a role in primary productivity include ocean temperature, dissolved oxygen levels, and salinity. These contributing factors along with light availability and nutrients such as nitrates, phosphates, and iron influence the amount of chlorophyll or phytoplankton productivity in a given area. Measuring the amount of chlorophyll production coupled with ocean temperature, oxygen levels, and salinity along a depth gradient gives us an idea of how productive the area is and where it is occurring in the water column.

Aloha Sharks and Johnston Atoll, the next couple of blogs will talk about the close encounters we had with the local shark and our visit to Johnston Atoll itself. See next bottomfish research expedition post: http://bit.ly/17RGrdg