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2006/ Day 24
Initial REEF Survey Results on Kure Atoll and Pearl and Hermes Atoll
Ellyn Tong, Hawai`i Audubon Society
Species abundance and diversity were sampled using the Reef Environmental Education Foundation (REEF)
survey method for reefs at Kure Atoll and Pearl and Hermes Atoll. These surveys involved snorkelers
recording the relative abundance they observed of reef fish species while swimming in a random pattern,
taking care to not swim over the same area twice. REEF fish surveys can also involve diving, but the
educators did not have that option on this particular trip. For the most part, the survey sites were
no deeper than 20 feet.
A chart of Kure Atoll with the thirteen REEF fish survey sites plotted.
Click on the chart to see a larger, high-resolution version. Credit: NOAA
Thirteen sites were surveyed in and around Kure Atoll and three at Pearl and Hermes Atoll. The Kure sites
were chosen so all corners of the atoll are represented with nine surveys on the inside reef and four on
the outside reef. Differing habitats were targeted. The north shore outside reef site, however, was not
attainable to give a full representation of all areas on Kure Atoll. The three Pearl and Hermes Atoll
sites were chosen to represent shallow reef and a deep-channel environment.
juvenile, endemic multiband or pebbled butterflyfish (Chaetodon
multicinctus) has found the perfect home in this coral head. Hawaiian
Islands National Wildlife Refuge, U.S. Fish and Wildlife Service, Dept. of
Interior. Photo: Claire Johnson/NOAA
The numbers of different species at each site differed from between 35-65 species, representing 34 families
of fish. The three sites with fewer than 40 species counted were shallow water, protected sites. The top
ten most common species by number were represented by six families and included the Pacific Gregory
(Stegastes fasciolatus), threadfin butterflyfish (Chaetodon auriga), spectacled parrotfish
(Scarus perspicillatus), convict tang (Acanthurus triostegus), whitebar surgeonfish (Acanthurus
leucopareius), bluespine unicornfish (Naso lituratus), blacktail wrasse (Thalassoma
ballieui), Hawaiian cleaner wrasse (Labroides phthirophagus), Hawaiian hogfish (Bodianus
bilunulatus), saddle wrasse (Thalassoma duperrey), and sea chub sp. Half of the most common
species are also endemic species, and the three species found at every site included the Pacific gregory,
blacktail wrasse, and the saddle wrasse. The two wrasses found at every site, the blacktail wrasse and the
saddle wrasse are endemic species.
The percent incidence of endemism was calculated for each site for number of fishes surveyed. Fish that
are endemic are those species that are thought to have evolved in the Hawaiian Islands and are found for
the most part in the Hawaiian Islands. Some of Hawaii’s endemic species are also found at Johnston Atoll.
Though 25% of the fish on our species list were endemic, seven of the sites showed 40% or higher rates of
endemism by number of fishes counted. This means that the endemic species have proportionally more
representatives than their non-endemic counterparts. Endemics may therefore be better suited, having
evolved certain life history characteristics to more efficiently live on Hawaiian reefs. Typically
island endemics are small bodied and have restricted geographic ranges.
The endemic blacktail or old woman wrasse, hinalea luahine (Thalassoma
ballieui) was one of three species found on every single snorkel site in the Northwestern Hawaiian Islands. Photo: Claire Johnson/NOAA
Most of the sites with high levels of endemism occur on the inside reef that faces the north. These sites
had close to or exceeded 40% endemism by number. An explanation of this endemism may be that these
environments with coral heads interspersed with sandy bottoms, provide suitable habitat for
butterflyfishes and wrasses, two families of fishes that have higher numbers of endemic representatives
than other families. For example, wrasses constitute over half of all endemics counted and need sandy
bottoms to burrow in when they sleep at night. Butterflyfishes often sleep in holes and in spaces
between many types of coral.
Recruitment may be an important factor favoring endemics, as endemic species may have evolved reproduction
and dispersal patterns more attuned for the Northwestern Hawaiian Islands than non-endemics. Ocean currents
and the timing of the availability of food for larvae may make the difference between which species
witnesses more recruits and which does not. On average for most coral reef fish, only one out of 250,000
eggs reaches adulthood. Most of the mortality occurs during the larval stage, with half of the larvae
succumbing to predators, and the other half starving due to lack of suitable food (Leggett and Deblois, 1994).
The yellowstrip coris (Coris
flavovittata) is another endemic species commonly found in the Northwestern Hawaiian Islands. Hawaiian Islands National Wildlife Refuge, U.S. Fish and Wildlife Service, Dept. of Interior. Photo: Claire Johnson/NOAA
Outside reef sites had lower rates of endemism, and this may be a result of those sites being more exposed
to top carnivores and having fewer niches for recruitment of juveniles and typically smaller bodied
endemic species. Some of these outside reef environments experience large wave events every year that
may exceed over twenty feet. While the waves are this large, few species of fish would find this
environment suitable. Transient species, like smaller surgeonfishes and chub would be more suited to
this environment than butterflyfishes and wrasses, which often develop territories that they keep and
defend for many years. There are no endemic surgeonfish and chub in Hawaiian waters (Hoover, 1993).
The South/Southeast sheltered reef showed a high rate of endemism (75-84%), and this may be
due to a somewhat strong surge current and lack of non-endemic schools of chub, convict tangs,
whitebar surgeonfish, and goatfishes that may not have been able to swim effectively against
the surge current. There were several species of wrasse, many of them tiny juveniles, which
are typically small bodied and quick, able to swim against the current.
Potter’s angelfish is an endemic species commonly found in the main Hawaiian
Islands, yet only found on a handful of the REEF fish survey sites in
the Northwestern Hawaiian Islands. Hawaiian Islands National Wildlife
Refuge, U.S. Fish and Wildlife Service, Dept. of Interior. Photo: Claire
In a paper by Drs. Edward DeMartini and Alan Friedlander, Spatial Patterns
of endemism in shallow water reef fish populations of the Northwestern Hawaiian
Islands, they showed through scientific surveys an increasing incidence
of endemism with increasing latitude. The four northernmost Hawaiian Islands were
observed to have the highest rates of endemism that reached in some parts 52%
by number. They surveyed 59 stations by snorkel and scuba. They were better
trained and had the advantage of using scuba that may have resulted in higher
reports of endemism than what we experienced. Most endemics are small bodied
and a diver on scuba is more likely to get an accurate count by carefully
looking under ledges and in holes for the smaller fishes, than a snorkeler.
One Hawaiian endemic not seen in REEF fish surveys was the Hawaiian grouper, Hapuu (Epinephelus
quernus). A larger species, reaching 32 inches or more, it does not follow the general rule
for small endemics. It is a member of the grouper family, a family whose members classically
take many years to reach adulthood, spawn in aggregations, and change their sex. Though it is
part of the bottomfish fishery, unfortunately very little is known about the life history of this fish.
colorful fish called a spectacled parrotfish or uhu ‘ahu’ula (Scarus
perspicillatus) is also an endemic species that was one of the top ten most commonly seen species in the Northwestern Hawaiian Islands. Photo: Claire Johnson/NOAA
The Hawaiian Islands are the most remote island chain on Earth. This isolation has supported the evolution
of many marine fish species that exist nowhere else on earth. Through REEF fish surveys the education
team was able to realize the unique abundance of these species on two atolls’ remote reefs. Preservation
of the Northwestern Hawaiian Islands as havens for endemics is important for their survival and our
knowledge and appreciation of how special and unique the Hawaiian Island archipelago truly is.
John P. 1993. Hawaii’s Fishes: A Guide for Snorkelers, Divers and Aquarists.
W.C. and E. Deblois. 1994. Recruitment in Marine Fishes: Is it Regulated
by Starvation and Predation in the Egg and Larval Stages? Netherlands Journal
of Sea Research 32 (2): 119-134.
thanks to the Kure Atoll, State Wildlife Refuge and the Hawaiian Islands
National Wildlife Refuge, U.S. Fish and Wildlife Service, Department of