21 August 2019 | Data Story

Nauru Rapid Biodiversity Assessment Project (BIORAP)

In 2015 a BIORAP was conducted in Nauru through the Department of Commerce Industry and Evironment by SPREP and other partners. The purpose of the Nauru BIORAP was to improve the state of knowledge of marine and terrestrial ecosystems, to provide a scientific basis for the conservation and management of nationally, regionally and globally important ecosystems and species. A particular focus was to identify areas of conservation value and to investigate opportunities for establishing marine and terrestrial protected areas. A fundamental principle is that decision-making should rest with resource owners and communities. The BIORAP provided opportunities for community members and Government staff to participate and receive training from the expert team.

KEY FINDINGS:
LAND -
FLORA: Nauru’s flora comprises about 56 native species (no endemics) and only 42 were located during the survey. Most of the other 14 species are likely to be extinct, or on the verge of extinction. The remaining native species are considered of critical importance ecologically and culturally.

INVERTEBRATES: Forty percent of both the moth and land snail fauna is native and 100% (all six) dragonflies are native. All 17 ant species recorded were exotic, including the highly destructive yellow crazy ant Anoplolepis gracilipes which was only detected at the port suggesting a recent incursion that could be eradicated.

REPTILE: The reptile community appears intact despite major habitat alteration. A total of seven species of reptiles were detected including two species of ground skinks, four species of gecko (one of these invasive), and one snake species (invasive). Molecular data indicate that the Micronesian Black Skink Emoia arnoensis nauru is an undescribed species of Emoia that is not closely related to E. a. arnoensis from Micronesia.

BIRD: A total of 36 bird species were recorded including two new records of seabirds. The endemic Nauru reed warbler (Acrocephalus rehsei) was found to be common over most of the island except for recently mined areas. The Micronesian pigeon (Ducula oceanica) exists on Nauru in very small numbers. Surveys of the black (Anous minutus) and brown noddy (A. stolidus) indicate that they are being harvested faster than they can breed.

MARINE -
CORAL REEFS: The reefs of Nauru have a low diversity of hard corals, though seven species were recorded that represented extensions of their known biogeographic range. All sites except one were heavily dominated by a single species of coral, Porites rus. There were five species of Acropora observed and colonies were rare. Acropora was reported to be more common in the past. One coral species found Pocillopora fungiformis, was previously only known from one site in Madagascar. It is listed as Endangered (IUCN) and as one of the top 50 “EDGE” (Evolutionarily Distinct & Globally Endangered) coral species in the world. Three other threatened coral species were recorded.

INTERTIDAL FLAT: The intertidal reef flat is fairly narrow with no lagoon and only a few shallow tidal pools. Algae (seaweeds) are the dominant organisms on the flats with 20 new species records for Nauru identified. Coral communities were rare. Introduced marine species associated with the fouling of wharves and ports were common including the bearded fire-worm (Hermodice carunculata) which has venom in its bristles that can cause a burning sensation.

INVERTEBRATES: The reefs of Nauru have a relatively low number of marine invertebrates. The total number of non-cryptic invertebrate species identified in this study was 79, representing 43 families, and including 41 new records for the country. The invertebrate fauna is dominated by sea urchins (Diadematidae), molluscs (Muricidae), sea cucumbers (Holothuridae) and crabs (Trapeziidae). Soft corals were documented for the first time in Nauru. Two giant clams (Tridacna maxima) known locally as “earinbawo” were found during the BIORAP. This was an important rediscovery as the species had previously been thought to be locally extinct as they had not been recorded since the 1980s. 12 Rapid Biodiversity Assessment of Republic of Nauru There was limited diversity and number of marine invertebrates that are targeted for harvesting. Only five species of sea cucumber were observed and in very low densities. Very few Turbo spp were found and no Trochus despite suitable habitat being available, which warrants further assessment as it may suggest over-exploitation.

FISH: The reef fish fauna within Nauru is dominated by Labridae (34 spp), Pomacentridae (30 species), Acanthuridae (21 spp), Chaetodontidae (21 spp), Balistidae (12 spp), Serranidae (11 spp) and Scaridae (10 spp). Mobile invertebrate feeders were the most common group (23.8%), while plankton eaters (19.2%), those with a diet of both invertebrates and fishes (12.8%) and fish eaters (10.3%) were also relatively diverse. Although the abundance of the reef fish fauna within Nauruan reefs was high relative to other nations, there were significant signs of overfishing. Several usually common groups of fish were under-represented, and the overall fish community structure was unbalanced with a high proportion of herbivorous species and a very low proportion of predators. There was a lack of large sized fishes like groupers and snappers. For five species most individuals were below the size at which they could breed, which was of concern. Whitetip reef sharks (Triaenodon obesus) were abundant at almost all sites.