Species Diversity

CRRF Marine Specimen Collection

The CRRF specimen collection is a product of our collections for the US National Cancer Institute (NCI). For 22 years we collected marine invertebrates and algae for NCI’s Natural Products Branch screening program looking for cancer drugs from the sea. NCI reference specimens were archived in our collection, in addition to invertebrates collected for other projects. The collection contains >10,000 lots from the Indo-Pacific and is particularly rich in the taxonomically difficult groups such as sponges, sea squirts, soft corals, and bryozoans. This collection provides a wealth of new species diversity and biogeographic information for the western tropical Pacific region, in particular. Of importance was one of the first uses of a submersible for deep water collections in Palau.

View the marine invertebrate and algae collection database

Following the end of the NCI contract CRRF was preparing to ship the entire collection to the Invertebrate Zoology department of California Academy of Sciences (CAS) in San Francisco and Division of Botany, Smithsonian Institution (SI). Unfortunately this process was interrupted in a dramatic way! In May 2015 at 2:40 AM a speeding, out of control car crashed through the wall of the CRRF building and came to rest into the main collection area. A fireball erupted within seconds engulfing the rooms while the driver, saved by airbags in the vehicle, fled the site. In the next few hours about one third of the CRRF collection was totally destroyed while the remainder was damaged by heat and smoke from the fire. The remaining 11,000 bottles of specimens had to be cleaned, melted lids replaced, new preservative added and then prepared for shipment. After several months of cleaning, the collection was then carefully packed into 45 barrels and loaded into a 20 ft shipping container. With permits acquired from Palau and other countries of origin, the collections were shipped to their new homes at CAS and SI in September. After the specimens are integrated into the main CAS and SI collection they will be available online at CAZ IZ and SI.

Increasing our knowledge of biological diversity through taxonomic study and ecology

Before species diversity can be assessed, we must be able to distinguish and identify individual species. Giving each entity (animal, plant, microbe etc.) a species name allows comparisons more broadly. Species are named through an organized process where the organism is described in a published document, the author recognizing that a given organism has not already been given a scientific name. The species description is usually published by a taxonomist in a technical journal or book and a ‘bionomial’ name (genus and species) is included in that written description. Once published, the author(s) name and date of publication is attached to the scientific name. For example, the humphead wrasse, Cheilinus undulatus Rüppell 1835, was described by Eduard Rüppell, a German naturalist, in 1835. The author’s name and date of publication allows a scientist to more easily track down where and when the original description was published.

How new species are named

Choosing the name for a new species is often an interesting process. In the case of a new species, the genus, the first part of the binomial name, may often already be described. The new species is for an organism that clearly falls within an already described genus, where the species have something in common. In this case, the second, or specific name, is the one that must be selected.

Palauastrea ramosa

Astrosarkus idipii

Mastigias papua etpisoni

But it may also be so different that a new genus must be created. Often the genus or species name refers to some morphological features, a color pattern or a geographic area. A good example is the stony coral genus Palauastrea, which was described in 1941 by Yabe and Sugiyama from Nikko Bay (the type locality) in Palau. The genus only has a single species, Palauastrea ramosa, what we would call “monotypic” or one type, but has a wide geographic distribution, instead of being endemic only to Palau (despite having been named for Palau).

A new species can be named in honor of a person, known as a “patronym”. The person for whom a new species is named may be a scientist who assisted with knowledge of the group, or someone who collected the species being named, or someone who provided support for the research work. It is a way of recognizing a significant contribution of some kind. CRRF named a seastar, Astrosarkus idipii, in honor of David Idip Sr., the former Director of the Bureau of Marine Resources. The genus was also new, and described at the same time the species, by Dr. Chris Mah in 2003.

Nearly all species descriptions have a single individual designated as the holotype, with additional specimens of the same organism and used in the original description as paratypes. The holotype and paratypes are usually actual preserved specimens, typically held in a museum collection somewhere in the world, and the name given is tied to the holotype in perpetuity. If a holotype is destroyed (say the museum where it was deposited was destroyed in a war and all collections lost), a new primary type can be designated.

Subspecies can also exist. These are organisms that don’t quite meet all the criteria to be considered full species with their own binomial name, but have some differences and are distinct in some way. All subspecies within a given species use the same binomial, but a third subspecific name is added. For example, the golden jellyfish of Palau is found in the lagoon area, but has also migrated into five separate marine lakes. Each of the five lake forms of the jellyfish were derived from the lagoon species, Mastigias papua (Lesson, 1830). In 2005 Dr. Michael Dawson named each of the five lake forms as separate subspecies for the five elected Presidents of Palau. Hence, the golden jellyfish found in Jellyfish Lake open to tourists is named Mastigias papua etpisoni, named after Palau’s 3rd president, Ngiratkel Etpison.

Species diversity in Palau

The levels of marine invertebrate species diversity known from Palau (as of 2009) are summarized in the book “Marine Environments of Palau” (Chapter 18). At that time, for example, 137 species of ascidians (sea squirts) were reported from Palau, based on collected specimens housed in museums. Francoise and Claude Monniot from the Paris National Museum of Natural History described over 80 new species (see Specimen Database and Publications) from CRRF collections, many of those were taken in Palau, while others were collected elsewhere . Specimen-based estimates are always more accurate than estimates from photographs or sight records, especially for difficult groups like ascidians.

Sponges are also notoriously difficult to identify to species level. CRRF has worked with numerous sponge taxonomists but the majority of our collection was identified by Dr. Michelle Kelly, enabling easy comparisons of yet unnamed species within the collection. A spin-off from these identifications is the small volume Splendid Sponges of Palau, the first version of a color e-field guide for sponges.

In recent years valuable contributions have been made to our understanding of the diversity and distribution of many other Indo-Pacific invertebrate taxa including flatworms, nudibranchs (sea slugs), echinoderms (crinoids, sea stars, sea cucumbers), and anthozoans (e.g. anemones and corals).

As taxonomic knowledge expands, the species diversity patterns of an area becomes clearer. For example, the number of stony (scleractinian) corals in Palau is not accurately known due to the difficult taxonomy of many species. The estimates have varied over the years, to as high as 425 species.

Dr. Charlie Veron, an authority of stony corals, puts the number of stony corals around the main island group of Palau at about 310 species and if the southwest islands of Palau are included, this adds another 20 species or so. For soft corals, absolute numbers are also hard to come by. Some authorities have estimated Palau has nearly 300 soft corals, but detailed collection work by CRRF now indicates this number is close to 150 documented species. If stony and soft coral numbers are combined, it appears the actual number of species in these groups are actually about 500 total species (considering that additions will be added).

For reef and coastal fishes, Robert Myers in his thorough 1999 book “Fishes of Micronesia” recorded 1,387 species of shallow water (less than 200 m depth) fishes from Palau. Since then many new species have been described from Palau and new geographic records for the country observed, photographed or collected. At present there is no single definitive list of fishes for Palau but for the present simply stating there are roughly 1,500 species of reef fishes in Palau is accurate. Taxonomic knowledge continually moves on (forward, we hope) and is never static for any group.

Palau’s Deep Reef and Slope to 300 m (1,000 ft)

Below the depth of about 60-75 meters where reef building corals drop off on the slopes of Palau, a new biological community appears which is dominated by other types of cnidarians (sea fans, sea anemones etc), echinoderms (sea stars, sea cucumbers etc) and to a lesser extent sponges. Gorgonians, soft corals, black corals and a variety of ahermatypic (non-reef building) corals occur here, none of which are found in shallower waters. Plants are essentially gone at these depths; no macroalgae occur, but encrusting coralline algae and other thin algal films can be found to perhaps as much as 150 m in Palau. Despite this lack of plant life, broken blades of sea grasses and bits of algae are swept down the slopes and build up in areas of the bottom where their decomposition provides some nutrients to the area.

At about 90-100 m primnoid gorgonians (limited to cold water) first appear and quickly become the dominant gorgonian down to 300 m. Black corals (Antipatharia) are also common, some of the species forming colonies with lengthy bottle-brush or feather type branches, while others are short or fan-like. The amazing benthic ctenophore, Lyrocteis imperiatoris, is found at the tops of some black corals bushes, enabling them to get up into the current where they can feed. A variety of sea anemones also occur here, with diversity probably higher than that found on the shallow reef a few hundred feet above. The diversity of sea stars (Asteroidea) is surprising, with quite a number of species which are rare in collections or completely unknown before our work. Delicate crinoids and large brittlestars occur on the gorgonians and rock faces. Many new species of fishes are found here, and they receive outsized attention due to their habitats and bright colors, so that fauna is increasingly becoming known. The invertebrates receive much less attention and still hold many new discoveries.

The environment on the deep reefs and slopes has low light, to the extent that light is nearly gone at 300 m depth, cool temperatures and a continual downslope transport of sediments from high up on the coral reefs above. Our submersible observations and collections have provided only a brief glimpse into the world of the deep reef and slope, which many new discoveries awaiting scientists who venture into this realm.

Marine Species Endemism in Palau

A particular species may be endemic, or unique to a certain geographic area. We could say, for example, that humans are endemic to planet Earth, making us an endemic species if you consider the whole earth. Marine endemics are generally not as common as terrestrial species, due to their dispersal mechanisms of planktonic larvae which may be transported long distances between islands across the open ocean. However, thanks to the application of genetics to species identification, marine endemism may also be more common than once thought, with the numbers of ‘cryptic’ species (as identified by genetic differences but not by previously recognized due to limited morphological differences) rising. An endemic species may deserve special protection because, by definition, it is found nowhere else. Other organisms considered endemic may not actually be such, but rather there is a lack of information about its geographic distribution.

A good example of this is, again, the Idip seastar, Astrosarkus idipi Mah 2003 from Palau. The first specimen of this large and colorful seastar was collected in Palau in 1997 and was immediately recognized as an unknown and unnamed species. A few more were collected later in Palau by CRRF using the Deepworker submersible, and it was thought it might be a Palauan endemic. In order to prepare the scientific description, the taxonomist studying the new species (Dr. Christopher Mah) needed to look for additional specimens in museum collections from elsewhere. In the Bishop Museum in Honolulu he found a specimen of the same species (which had not yet been identified) from the Marshall Islands, and later, at the Natural History Museum in Paris, found another one from Reunion Island in the western Indian Ocean. So with a little scientific detective work, A. idipi went from being a possible Palauan endemic to a species that is obviously widespread throughout the deep waters of the tropical Indo-west Pacific. This does not diminish the value of describing this new species, but points out how little we really know about marine life and its distribution in the tropical Pacific.

Biogeography of Marine Species

The Coral Triangle is considered to be the area of the Indo-Pacific with the highest shallow water marine diversity. It includes the Philippines, Indonesia, East Timor (Timor Leste), Malaysia, Papua New Guinea, and possibly the Solomon Islands. Palau lies to the east of the Coral Triangle, 800 km east of Mindanao, Philippines. While Palau has the highest diversity in Micronesia, for nearly all groups Palau has only a subset of the genera and species found within the Coral Triangle. It is well established that for most marine organisms, the further east one moves away from the Coral Triangle into the Pacific, the fewer species there are within any given genus or family.

The numbers of habitats within a given region are also important for determining the number of species likely to be present. Gustav Paulay in 2003 described the marine species diversity of Guam, some 1,200 km from Palau with a relatively complete listing, providing a “nearby” geographic comparison to Palau. The same groups of organisms will likely have more species in Palau than they would in Guam because 1) there are more marine habitats in Palau and 2) Palau is closer to the Coral Triangle’s center of marine diversity. A comparison of these same groups between Palau and the Philippines, however, would show Palau with fewer species. Palau probably has close to as many habitats as the Philippines, but is much smaller in N-S extent (Palau archipelago: 160km vs. Philippines archipelago: 1,900 km) with less geographic diversity and is outside the Coral Triangle.

Palau itself presents some of its own interesting zoogeographic comparisons. Tobi Island of Hatohobei State, one of the oceanic southwest islands of Palau, is 550 km from the main Palau group. It is closer in proximity to the Coral Triangle, only 250 km from several large Indonesian islands, than to the rest of Palau. However, it has fewer species than the main Palau archipelago when considering some large marine groups, such as fishes, what we might call “depauperate”. This is largely due to the lack of diversity of marine habitats on Tobi, which has only a narrow fringing reef and no lagoon. However, because it is closer to the Coral Triangle it has some species in common with that geographic area that do not occur in the main Palau group to the northeast. These include the false clown anemonefish, Amphiprion ocellaris, the spine-cheek anemonefish, Premnas biaculeatus and the barred soapfish, Diploprion bifasciatum. There are many other examples of organisms, especially sponges, that occur on the reefs of Tobi and not in the main Palau group, yet the overall number of species is less. The distance between Palau and the Coral Triangle acts like a “filter” to limit those species that can cross the barriers, while the reduced number of habitats at some islands make it difficult for some species that might be able to cross the barriers survive once they have arrived.