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The Hawai‘i Coral Reef Assessment and Monitoring Program (CRAMP) was established in 1999 to describe spatial and temporal variation in Hawaiian coral reef communities in relation to natural and anthropogenic factors. In this study, we analyzed changes over a 14-yr period (1999 to 2012) based on data from 60 permanent reef stations at 30 sites in the main Hawaiian Islands. Overall mean statewide coral cover, richness, and diversity did not vary significantly since the initial surveys, although local variations in coral cover trends were detected. The greatest proportion of stations with significant declines in coral cover was found on the island of Maui (0.4), and Hawai‘i Island had the highest proportion of stations with significant increases (0.67). Trends in coral cover at some stations varied over time due to acute (e.g., crown of thorns outbreak) and chronic (e.g., sedimentation) disturbances. Stations with increasing coral cover with the potential for recovery from disturbances were identified for possible management actions in the face of future climate change. The Hawaiian archipelago, located in the center of the subtropical Pacific, has experienced a temporary reprieve from steadily increasing temperatures over the past several decades due to a downturn of temperatures at the end of the last cycle of the Pacific Decadal Oscillation (PDO) in 1998. In 2014, however, temperatures increased dramatically in Hawai‘i, resulting in a major coral bleaching event with associated mortality. Temperature models predict severe bleaching events to increase in frequency and intensity in coming decades with concomitant decline in Hawaiian corals. Trends reported in this study provide a baseline that can later be used to test this predicted decline associated with future warming.
Little is known about the basic life history of most species of precious corals (Octocorallia: Coralliidae). Three commercially valuable precious coral species (Paracorallium japonicum, Corallium elatius, and C. konojoi) were sampled from the Ryukyu Archipelago to study their reproductive biology. To determine features of their gamete differentiation, samples were thin-sectioned for examination with a digital light microscope, and diameters of sperm sacs and oocytes were measured. Sexual reproduction strategy in all three species was determined to be gonochoristic broadcast spawning. Almost all gonads were found to be differentiating in siphonozooids, not in autozooids. Sex ratio of C. konojoi was around 1 : 1; that of P. japonicum and C. elatius seemed biased toward females but did not deviate significantly from 1 : 1. Number of gonads per polyp in these three species was fewer and they were generally smaller in diameter in comparison with other octocorals reported elsewhere, suggesting comparatively low fecundity for these species of Coralliidae from southern Japan. Spawning of these three species appears to occur during summer, mostly from May to August.
The Hawaiian green turtle, Chelonia mydas Linnaeus, is a marine herbivore known to feed on sea grasses and seaweeds. On the east side of the island of Hawai‘i, at high tide, green turtles have been observed feeding on a terrestrial, salt-tolerant turfgrass: seashore paspalum, Paspalum vaginatum Swartz, first introduced to the Hawaiian Islands in the 1930s. The role of this grass in green turtle nutrition is unknown. Paspalum vaginatum samples were collected at Keaukaha Beach Park, Hilo, and analyzed for nutritional composition (percentage water, percentage ash, caloric value, C : N ratio, percentage protein, and percentage lignin). In addition, two red seaweeds, Pterocladiella capillacea (Gmelin) Santelices & Hommersand, a common food source for green turtles, and Ahnfeltiopsis concinna (J. Agardh) Silva & DeCew, an abundant high-intertidal species sometimes consumed by turtles, were analyzed for comparison. In contrast to the two seaweed species, Paspalum vaginatum contained approximately half the ash; 300–1,500 more calories/g ash-free dry weight; three to four times greater total protein; and 3–19 times higher lignin content. Green turtles in Hawai‘i may opportunistically consume P. vaginatum because of its local abundance and/or its high protein and caloric content. In foraging areas where native macroalgal species have declined and/or turtle carrying capacity has been reached, green turtles may exploit new foods, such as seashore paspalum, and perhaps mitigate decline in somatic growth rates and body condition.
Song birds that have been artificially introduced to isolated areas are fruitful material for investigating changeability of songs within a limited period of time. I studied songs of Japanese Bush-warblers, Cettia diphone, which were introduced from Japan to the island of O‘ahu (Hawaiian Islands) ca. 80 yr ago. These warblers on O‘ahu sang acoustically simpler songs at lower frequencies than the warblers on Honshu, the main island of Japan. Previous studies found similar tendencies on small peripheral Japanese islands. Morphological characteristics indicated that the warblers on the Hawaiian Islands did not originate from insular subspecies in Japan. Therefore, the acoustic structure of their songs may have changed during their 80 yr on O‘ahu. Possible factors driving this rapid change are relaxed sexual selection and/or the sound transmission properties of the island habitat.
Due to habitat loss, disease, and introduction of nonnative species, many native species in Hawai‘i have gone extinct or are at risk of extinction. As a result of interspecific interactions such as pollination, the decline, loss, or introduction of species can have cascading effects on island ecosystems. We studied Hylaeus spp., Hawai‘i's yellow-faced bees, the only native bees in Hawai‘i. This group of potentially important pollinators has been largely overlooked until recently, and its conservation status and ecological role are virtually unknown. We investigated how native (Hylaeus spp.) and nonnative (Apis mellifera) bees interact with flowering plants in a large-scale pasture-to-forest restoration system. We used pan traps and nets to collect bees in mature forest, remnant corridors, planted Acacia koa tracts, and open pastureland. We removed pollen from each specimen and identified it using pollen samples collected on-site. We found that Hylaeus spp. were more likely to carry less pollen and more likely to exhibit higher pollinator fidelity compared with A. mellifera. By contrast, A. mellifera was more likely to carry mixed pollen and forage on invasive plant species. This is the first investigation in Hawai‘i to compare patterns of pollen carriage between native and nonnative bees and the first study to document pollen carried by Hylaeus spp. in the context of forest restoration.
The islands of remote Polynesia contain ant faunas that have been largely introduced anthropogenically. I employed nonmetric multidimensional scaling ordination analyses to evaluate patterns of ant species assembly on 42 islands across remote Polynesia. Patterns on islands in the Hawaiian archipelago were distinctly separate from those of more southerly islands. Patterns on high islands were distinctly separate from those of atolls and low-lying islands. Patterns on small islets on the barrier reefs of high islands were more similar to those of distant atolls than those of the nearby high islands. Latitude and elevation were most strongly correlated with ordination axes; area and longitude were weakly correlated with ordination axes. Patterns are consistent with human-assisted dispersal through long-distance shipping as a primary vector of colonization, and with a greater diversity of habitat types with increasing island elevation. Similar results were obtained when a subset of 19 islands that had been more thoroughly surveyed was analyzed. I also examined patterns in species composition among communities (within islands) on three French Polynesian islands (Bora Bora, Huahine, and Moorea). On all three islands, sites grouped together distinctly in ordination space as a function of the dominant ant species. A substantial number of species pairs co-occurred less frequently than predicted by chance. Although interspecific competition appears to be important in structuring ant communities within islands, habitat affinities probably also play a role.
For many landholders in the South Pacific, weed control of Mikania micrantha Kunth is conducted by manual or mechanical means, leaving fragments on or below the ground to reshoot and grow. Effects of age, length (number of nodes), and pattern of burial on the survival of stem sections of M. micrantha were examined in the field in Viti Levu, Fiji. The experiment was arranged in a randomized factorial design, with number of nodes, age of stem sections, and pattern (depth and orientation) of stem burial as factors. Stem sections with two or three nodes had significantly greater survival (30% and 25%, respectively) than those with one node (12%). Mature stem sections had a significantly greater survival rate (31%) than young stem sections (13%) when buried in either the horizontal or the vertical position. Vertical plantings had significantly greater survival (43%) than horizontal plantings (10%), and for both orientations survival decreased with depth of burial. Only 8% of stem sections survived when cut into smaller (3 to 5 cm) sections and buried at a depth of 10 cm. This study revealed that cutting the M. micrantha stems into smaller sections (<3 cm) and burying them at depths of 10 cm or greater would improve the overall management of M. micrantha in crop and noncrop systems.
Proper taxonomic classification of species is essential to the conservation of rare species to ensure that they garner needed protection. This study was undertaken to determine relationships among the Hawaiian representatives of Cryptocarya. This genus is represented in Hawai‘i on the islands of Kaua‘i and O‘ahu, where it is currently classified as a single species (C. mannii) and not considered endangered. It had previously been recognized as two species, C. mannii on Kaua‘i where it is relatively abundant and C. oahuensis on O‘ahu. O‘ahu plants have been in decline since their discovery over 100 yr ago and now only one naturally occurring plant is known. RAPD analysis demonstrates that populations on Kaua‘i are genetically distinct from those on O‘ahu. Sequence analysis of nuclear (ITS) and plastid (trnK intron) gene regions shows distinctions among plants from different islands (ITS: four or five base substitutions plus one repeat length difference; trnK intron: one base substitution plus one repeat length difference). Differentiation identified here is comparable with that of some congeneric species elsewhere and is consistent with recognition of C. oahuensis and C. mannii as separate species. Both species are members of the Asian-Australian clade in a broader phylogenetic analysis. Morphological traits that distinguish each species are examined, and a key to the species is provided. Conservation measures to protect the critically endangered C. oahuensis are discussed.
Sixteen species of reptiles (two sea turtles, seven geckos, six skinks, and one monitor lizard) are recorded from Lukunor Atoll, Federated States of Micronesia. None is endemic to the atoll, and nearly all are widespread in Micronesia, and in many cases well beyond. The gecko Perochirus ateles has the highest incidence of occurrence, being recorded on 17 of the 18 islands, followed by the skink Lamprolepis smaragdina (14 islands), and the gecko Gehyra oceanica (13 islands). The skinks Emoia caeruleocauda and E. impar were among the most common lizards wherever they occurred on the atoll but were observed on only eight and six of the islands, respectively, and occurred together on only two of them. The Pacific monitor, Varanus indicus, was introduced during the Japanese administration, and the common house gecko, Hemidactylus frenatus, probably sometime after World War II. Origins of the other species are less certain; some possibly arrived by natural dispersal and others assisted by humans.
The parasitic copepod genus LernaeosoleaWilson, 1944 (Chondracanthidae, Copepoda) is reported for the first time from the Pacific Ocean and the shortjaw eelpout, Lycenchelys jordani (Zoarcidae, Perciformes) based on specimens collected off British Columbia, Canada, and identified as Lernaeosolea cf. lycodis. Microscopic examination of the copepods revealed features previously unknown for Lernaeosolea adult females: namely, a simple mouth anteriorly delimited by a labrum, maxillules, maxillae, maxillipeds, and one pair of vestigial swimming legs. A new diagnosis for Lernaeosolea is provided.