Pacific Science, vol. 65, no. 3 (2011)

Ant-Plant Mutualism in Hawai‘i? Invasive Ants Reduce Flower Parasitism but Also Exploit Floral Nectar of the Endemic Shrub Vaccinium reticulatum (Ericaceae)
Richard Bleil, Nico Blüthgen, and Robert R. Junker, 291

Ants had been absent from the Hawaiian Islands before their human introduction. Today they cause severe alterations of ecosystems and displace native biota. Due to their strong demand on carbohydrate-rich resources, they often exploit floral nectar of native Hawaiian plant species with largely unknown consequences for the plants’ reproduction. We examined effects of flower-visiting invasive ants on reproduction of the endemic shrub Vaccinium reticulatum (Ericaceae) in Hawai‘i Volcanoes National Park. Ant densities in flowers were high and floral nectar was excessively exploited, which may lead to a reduced visitation rate of pollinators. However, the ants’ presence on flowers strongly reduced flower parasitism by caterpillars of the introduced plume moth Stenoptilodes littoralis and thus decreased the loss of flowers and buds. This is, to our knowledge, the first documented mutualism between invasive ants and an endemic plant species in Hawai‘i. Developed fruits of this partly self-
incompatible plant, however, bore relatively low proportions of viable seeds, irrespective of the experimentally controlled visitor spectrum of the flowers. This may indicate that ants do not function as pollinators and that effective pollinators (probably Hylaeus bees) are scant or absent.

Diets of the Sympatric Pacific Sheath-Tailed Bat (Emballonura semicaudata rotensis) and Mariana Swiftlet (Aerodramus bartschi) on Aguiguan, Mariana Islands
Ernest W. Valdez, Gary J. Wiles, and Thomas J. O’Shea, 301

The Pacific sheath-tailed bat (Emballonura semicaudata rotensis) and Mariana swiftlet (Aerodramus bartschi) are two rare insectivorous taxa restricted to the southern Mariana Islands in western Micronesia. It is believed that populations of both have dwindled because of impacts to their food resources. However, there is little information on the food habits of A. bartschi and none exists for E. s. rotensis. In an effort to better understand the feeding habits of both, we investigated their diets using guano analysis. Guano was collected from two roosts in caves during a 2-week period in June and July at the onset of the rainy season. Important orders of insects consumed (percentage volume) by bats roosting at one cave included hymenopterans (64%), coleopterans (10%), lepidopterans (8%), isopterans (8%), and psocopterans (5%), whereas those at a second cave included lepidopterans (45%), hymenopterans (41%), coleopterans (10%), and isopterans (5%). Swiftlets, which roosted in only one of the caves, fed mostly on hymenopterans (88%) and hemipterans (6%). Significant differences existed between the two taxa in several insect orders eaten, with E. s. rotensis consuming more lepidopterans and coleopterans and A. bartschi taking more hymenopterans and hemipterans. Within Hymenoptera, bats fed more on ichneumoideans, whereas swiftlets ate more formicid alates and chalicidoideans. This new information on the feeding habits of E. s. rotensis and A. bartschi provides insight on the complexity of their diets during June and July, and serves as baseline information for future studies and management of their habitat.

Current Distribution and Abundance of O‘ahu ‘Elepaio (Chasiempis ibidis) in the Wai‘anae Mountains
Eric A. VanderWerf, Stephen M. Mosher, Matthew D. Burt, and Philip E. Taylor, 311

The O‘ahu ‘Elepaio (Chasiempis ibidis) is an endangered forest bird endemic to O‘ahu and has declined steadily during the past century. Current information on distribution and abundance is needed to help assess the species status and identify areas where recovery efforts can be focused. We used spotmapping methods to census O‘ahu ‘Elepaio in all suitable forest habitat in the Wai‘anae Mountains from 2006 to 2010 and compared results with previous surveys from the 1990s. We detected a total of 300 O‘ahu ‘Elepaio, including 108 breeding pairs and 84 single males. The sex ratio was strongly male biased due to nest predation on females. Their distribution was extremely fragmented, and the only concentrations were in ‘Ēkahanui (38 pairs), Schofield Barracks West Range (40 pairs), and Pālehua (15 pairs). We failed to detect ‘Elepaio in many areas where they were observed in the 1990s. ‘Elepaio have become more sparse in other areas, indicating that they are continuing to decline. Nest predation by alien black rats (Rattus rattus) and mosquito-borne diseases are the greatest threats. Rat control programs have helped reduce nest predation and stop declines in several areas, but only a fraction of remaining ‘Elepaio benefit from active management and further declines can be expected unless rats are controlled on a larger scale. Alternative methods of rat control should be explored, and restoration of native trees that are less attractive to rats might provide safer nest sites and reduce the need for rat control.

Distribution and Abundance Estimates for Cetaceans in the Waters off Guam and the Commonwealth of the Northern Mariana Islands
Gregory L. Fulling, Philip H. Thorson, and Julie Rivers, 321

Cetacean distribution and abundance are reported from the first systematic line-transect visual survey in the waters of Guam and the Commonwealth of the Northern Mariana Islands (CNMI). The survey was conducted during January–April 2007 following standard line-transect protocols. Trackline coverage (11,033 km) was dominated by high sea states (88.2%); however, 13 cetacean species were recorded. The sperm whale (Physeter macrocephalus) was the most frequently encountered whale, followed by Bryde’s and sei whales (Balaenoptera edeni and B. borealis, respectively). Occurrence of the sei whale is unique, because the species had not been confirmed to occur south of 20° N. The pantropical spotted dolphin (Stenella attenuata) was the most frequently sighted delphinid, followed by the striped dolphin (Stenella coeruleoalba) and false killer whale (Pseudorca crassidens). Humpback whales (Megaptera novaeangliae) were acoustically detected and later seen off Saipan. Numerous cetacean sightings were associated with steep bathymetric features including the West Mariana Ridge, the Mariana Ridge, and the Mariana Trench. Abundance estimates were based on 80 on-effort sightings for 12 species. Species were pooled into three separate groups for estimating detection probabilities: Balaenoptera spp., blackfish (medium-size odontocetes), and small dolphins. A separate detection function was generated for the sperm whale. Precision of abundance estimates are very low for all species due to low sighting rates and high sea states; however, these abundance estimates serve as the best scientific data available for the area and establish vital baseline information for future research efforts.

Biological Characteristics of the Spotcheek Emperor, Lethrinus rubrioperculatus, in the Northern Mariana Islands
Michael S. Trianni, 345

As a result of commencement of an incipient commercial fishery in the southern islands (SI) of the Commonwealth of the Northern Mariana Islands (CNMI), biological characteristics for the spotcheek emperor, Lethrinus rubrioperculatus, were estimated from the CNMI SI, including seasonality of spawning, sex ratios, length at sexual maturity (LM), length at transition (LT) to male phase, age, and growth. LM and LT estimates corresponded to ages of 1 and 3–4 yr, respectively, and are important in managing hermaphroditic species such as the spotcheek emperor by ensuring that fishery size selection does not significantly reduce effective stock reproduction. Age of the oldest fish was 8 yr, with South Southern Islands (SSI) fish mostly 0–2 yr old and North Southern Islands (NSI) fish 1–4 yr old. Average size of 0-age fish was 22.2 cm fork length (LF) from the SSI and 18.7 cm LF from the NSI, indicating an initial high growth rate not captured by specimen collection. Growth curves for the NSI and SSI were significantly different at the 5% level. Age and growth parameters were estimated using age- and length-based methods, which resulted in similar values for instantaneous growth coefficient (k) and asymptotic length (L∞). Results support further study into life history characteristics of the spotcheek emperor, in particular maximum age and lengths at maturity and transition, in other locations in the CNMI SI as well as in other Indo-Pacific jurisdictions.

First Documented Attack on a Live Human by a Cookiecutter Shark (Squaliformes, Dalatiidae: Isistius sp.)
Randy Honebrink, Robert Buch, Peter Galpin, and George H. Burgess, 365

An adult long-distance swimmer attempting to cross the ‘Alenuihāhā Channel between the Hawaiian islands of Hawai‘i and Maui was twice bitten by a cookiecutter shark (Squaliformes, Dalatiidae, Isistius sp.). One of these bites presented as an open, round, concave wound typically observed in cookiecutter shark bites inflicted by members of this genus on a broad spectrum of large biota such as marine mammals, elasmobranchs, and bony fishes. The open wound was debrided, subjected to negative pressure wound therapy, and a split thickness skin graft harvested from the left thigh. Postoperative recovery was complicated by delayed healing of the inferior portion of the graft, and cultures and biopsy were normal skin flora and normal tissue, respectively. At 6 months after the incident, the area appeared to be healing with a stable eschar, and by 9 months the wound was healed. Humans entering pelagic waters at twilight and nighttime hours in areas of Isistius sp. occurrence should do so knowing that cookiecutter sharks are a potential danger, particularly during periods of strong moonlight, in areas of man-made illumination, or in the presence of bioluminescent organisms.

Marine Sponges, Other Animal Food, and Nonfood Items Found in Digestive Tracts of the Herbivorous Marine Turtle Chelonia mydas
in Hawai‘i

Dennis J. Russell, Stacy Hargrove, and George H. Balazs, 375

Although the usual diet of Chelonia mydas comes from algae and sea grasses (plant material), animal material has been found in samples taken over the past 35 yr. The small black-brown protein sponge Chondrosia chucalla resembles the alga Codium arabicum in size, color, and texture, and both grow next to each other on the reefs. We hypothesize that turtles are actively seeking and eating these sponges and not mistaking them for C. arabicum. Both protein and silica sponges occur in the diet of Chelonia, but only 6.8% of the time are eaten in addition to their usual plant diet. Thirty different kinds of other animals were found in the samples, including Cnidaria, Mollusca, Crustacea, Insecta, Echinodermata, squid, fish, tumor flesh, and other animals but in low frequency (5%). Most of the miscellaneous nonfood debris items were terrestrial leaves, plastic, paper, string, fibers, hair, and paint chips but also in low frequency (<7%). Among animal food items known to have nutritional value, the protein sponge C. chucalla could be contributing an important nutritive factor, but this needs further research.

Origin of the Helminth Community of an Exotic Invasive Lizard, the Brown Anole, Anolis sagrei (Squamata: Polychrotidae), in Southwestern Taiwan
Gerrut Norval, Charles R. Bursey, Stephen R. Goldberg, Jean-Jay Mao, and Kerry Slater, 383

Composition of the helminth community of the brown anole, Anolis sagrei, an exotic invasive species in Taiwan, was studied to identify the emigration point of this lizard. A total of 5,757 helminths was found, of which 5,734 (99.6%) were the nematode Cyrtosomum penneri. Also found were the digenean Mesocoelium monas (21, 0.4%) and one each of the nematodes Parapharyngodon sp. (female) and Acuariidae gen. sp. (larva). Cyrtosomum penneri has previously been reported in A. sagrei in Florida, supporting the contention that the Taiwan population of A. sagrei originated from Florida. This report provides a basis upon which future A. sagrei parasite studies in Taiwan can be based, and a helminth list for A. sagrei is included for future reference.

Additions to the Myxomycetes of Singapore
Wayne C. Rosing, David W. Mitchell, Gabriel Moreno, and Steven L. Stephenson, 391

Much of Southeast Asia remains understudied for myxomycetes (plasmodial slime molds or myxogastrids). This survey of myxomycetes was carried out at 12 study sites throughout Singapore during March 2009. Sporocarps that developed in moist-chamber cultures of bark, forest floor litter, and aerial litter were used to supplement field collections. In addition, a series of samples of various types of plant litter collected from one other study site during the summer of 2004 was processed for myxomycetes. Collectively, these efforts yielded 76 species of myxomycetes in 26 genera. Thirty-six species are new records for Singapore. The latter includes two previously unpublished records along with one collection of Didymium and one collection of Trichia that could not be assigned to any known species.

Association Affairs, 401

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