Pacific Science, Volume 62, Number 4, 2008
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ItemFirst Record of a Pearlfish, Carapus mourlani, Inhabiting the Aplysiid Opisthobranch Mollusc Dolabella auricularia.(Honolulu, University of Hawaii Press, 2008-10)Adult individuals of the pearlfish Carapus mourlani (Petit, 1934) occur commonly in the mantle cavity of the opisthobranch mollusc Dolabella auricularia (Lightfoot, 1786) in shallow marine waters of the Gulf of Chiriquı´, Pacific Panama´. Nearly 30% of the molluscan hosts collected during the day on a coral reef contained one or two fish. Feeding observations of a captive fish as well as the intact condition of the host’s ctenidium and other internal organs suggest that C. mourlani is an inquiline commensal and not parasitic. Fish curl around the ctenidium during the day and capture microcrustaceans when the fish emerge from their host at night to feed. From low-light infrared video recordings, Carapus was observed to accurately grasp rapidly swimming amphipods in nearly total darkness and ingest them. This symbiotic relationship appears to benefit Carapus by allowing the fish to avoid predators during the day and to forage at night.
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ItemSeasonal Occurrence and Aggregation Behavior of the Sea Urchin Astropyga pulvinata (Echinodermata: Echinoidea) in Bahia Culebra, Costa Rica(Honolulu, University of Hawaii Press, 2008-10)Between October 2003 and July 2005, aggregation behavior of the sea urchin Astropyga pulvinta Lamarck was studied in Bahı´a Culebra, Costa Rica. This sea urchin forms aggregations during part of the year and then disappears. I quantified the number of individuals present in a defined area each month, their aggregation behavior between day and night, and their size. Also, temperature and nutrient concentrations of the water were sampled. There were significantly more individuals in aggregations during the colder, upwelling season (December to April). Aggregations consisted of adult individuals that exploit food during the upwelling season. Moreover, these aggregations were used as a refuge by several fish species of high commercial value for the aquarium trade. These sea urchin populations could suffer as extraction of ornamental fishes and urchins increases. Their abundance and behavior should continue to be monitored as an indication of the ecological health of the community.
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ItemAcropora (Anthozoa: Scleractinia) Reproductive Synchrony and Spawning Phenology in the Northern Line Islands, Central Pacific, as Inferred from Size Classes of Developing Oocytes.(Honolulu, University of Hawaii Press, 2008-10)Little is known of the timing of reproduction in central Pacific coral populations near the equator. Oocyte pigmentation and size comparison with sizes of mature eggs reported in published literature were used to infer intraand interspecific synchrony and probable spawning phenology in 15 species of Acropora from Palmyra and Kingman atolls in the northern Line Islands. Sampling at both atolls took place in March–April 2002 and 2004. Oocyte sizes were determined from microdissections of fixed, decalcified samples. The majority (91.2%) of samples (n ¼ 209) were gravid, with high levels of fertility in most (84.3%) samples. Statistically discrete oocyte size classes could be distinguished in most taxa at each atoll in each year. These discrete oocyte size classes suggest that several episodes of spawning, involving multiple species, take place over 2 or 3 months beginning in early spring. These data, which are the first observations of coral reproductive synchrony in the Line Islands, support the results of other recent studies, suggesting that reproductive synchrony can be a feature of equatorial reef assemblages where the annual ranges of sea-surface temperature and tidal amplitude are small.
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ItemDemographic Parameters of Yellowfin Croaker, Umbrina roncador (Perciformes: Sciaenidae), from the Southern California Bight.(Honolulu, University of Hawaii Press, 2008-10)The yellowfin croaker, Umbrina roncador Jordan & Gilbert, 1882, is a common nearshore and surf-zone species in the southern California bight. Age was determined for individuals (n ¼ 1,209) using annual increments in otoliths, and size at age was modeled using the von Bertalanffy growth curve (Ly ¼ 307:754 mm, k ¼ 0:278 yr_1, t0 ¼ _0:995 yr; maximum age ¼ 15 yr). Females (Ly ¼ 313:173 mm, k ¼ 0:307 yr_1, t0 ¼ _0:771 yr) grew significantly faster and larger than males (Ly ¼ 298:886, k ¼ 0:269 yr_1, t0 ¼ _1:072 yr). Age and growth modeling based upon otolith length (OL) and width (OW ) measurements were assessed and were consistent with body measurements. Males and females were found in all size classes and in an overall 51 :49 ratio that was not significantly different from a 50% sex ratio, suggesting that these fish are gonochores. Fish were reproductive during summer months, with gonadosomatic indices (females, 5.65%; males, 5.51%) consistent with group-spawning fishes. Data from two separate monitoring programs indicated that yellowfin croaker catch-per-unit-effort (CPUE) fluctuated appreciably from 1992 to 2006 on both spatial and temporal scales. CPUE also declined significantly in the latter years of these programs. Based on samples collected between 2003 and 2004, an estimate of overall annual total mortality was A ¼ 0:4492, and instantaneous coefficient of total mortality was estimated at Z ¼ 0:5964. Recruitment year classes were back calculated using annual survivorship. Year class strength was variable and declined significantly by the end of this study. Considering the high temporal and spatial variation in estimates of abundance and recruitment, coupled with the likelihood that these fish employ a probable group-spawning reproductive behavior, we recommend a cautious approach for the future management of this species.
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ItemMaximum Annually Recurring Wave Heights in Hawai‘i.(Honolulu, University of Hawaii Press, 2008-10)The goal of this study was to determine the maximum annually recurring wave height approaching Hawai‘i. The motivation was scientific as well as administrative: to enhance understanding of the recurring nature of dominant swell events, as well as to inform the Hawai‘i administrative process of determining the ‘‘upper reaches of the wash of the waves’’ (Hawai‘i Revised Statutes [H.R.S.] § 205-A), which delineates the shoreline. We tested three approaches to determine the maximum annually recurring wave, including log-normal and extremal exceedance probability models and Generalized Extreme Value (GEV) analysis using 25 yr of buoy data and long-term wave hindcasts. The annual recurring significant wave height was found to be 7.7G0.28 m (25 ftG0.9 ft), and the top 10% and 1% wave heights during this annual swell was 9.8G0.35 m (32.1 ftG1.15 ft) and 12.9G0.47 m (42.3 ftG1.5 ft), respectively, for open North and Northwest Pacific swell. Directional annual wave heights were also determined by applying hindcasted swell direction to observed buoy data lacking directional information.
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ItemRelationships between Otolith Size and Body Size for Hawaiian Reef Fishes.(Honolulu, University of Hawaii Press, 2008-10)Estimating body size of fishes from remains recovered from piscivores, archaeological sites, and sedimentary deposits is desirable but rarely accomplished because the relationships between the size of a fish and its durable anatomical structures are largely unknown. Regression equations to predict the size or weight of 41 common Hawaiian reef fishes from sagittae (saccular otoliths) are presented. Data are also grouped into higher taxa to permit size predictions when otoliths cannot be assigned to species.
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Item(Rhodophyta: Ceramiales) in a Hawaiian Fishpond: An Assessment of Removal Techniques and Management Options.(Honolulu, University of Hawaii Press, 2008-10)Acanthophora spicifera (Vahl) Børgesen was unintentionally introduced to Hawai‘i in 1950 and has since become the most common nonindigenous algal species in the main Hawaiian Islands. On the west coast of Hawai‘i Island it has been documented at three sites, including Kaloko Fishpond in Kaloko- Honoko¯ hau National Historical Park. The fishpond has an open connection to the sea, increasing the risk that A. spicifera will establish itself on neighboring shallow coral reefs and rocky intertidal habitats. To diminish that risk and to develop an efficient management strategy, a range of approaches was assessed to control this invasive alga in Kaloko Fishpond. Removal techniques were labor intensive and had limited effect. All experiments showed a substantial initial decrease in algal density, but the long-term effect was minimal because of rapid regrowth. The most promising removal method was the use of submerged shelters to raise local densities of herbivorous fishes. Fishes grazed the alga and quickly reduced the biomass. However, the large number of predators and absence of topographical structure will make it challenging to provide sufficient shelters to increase the herbivorous fish population in the entire fishpond. A management strategy to substantially reduce the algal biomass in the fishpond includes a combination of biological control and periodic manual removal of the alga.
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ItemInventory of Thysanoptera Collected from French Polynesia.(Honolulu, University of Hawaii Press, 2008-10)A survey for Thysanoptera was conducted in the Society (Tahiti, Moorea, and Raiatea), Marquesas (Hiva Oa, Nuku Hiva, Ua Huka, and Ua Pou), and Austral islands (Rurutu and Tubuai) archipelagos in French Polynesia from September 2003 to November 2005. At least 55 thrips species in 36 genera and three families were identified from 823 slide-mounted specimens that were collected from 61 host plants in 33 families. Twelve species are considered to be important pests. The greatest diversity of species, 43 (77%), was collected from the Society Islands, with 60% being recorded from Tahiti alone. Species diversity was intermediate in the Marquesas Islands at 43% (24 species collected), with 35% or 19 species being recorded from Nuku Hiva. Lowest diversity was recorded for the Austral Islands, with 38% or 21 species being found in that archipelago. Less than 10% of collected species are likely to be native, with the majority of identified thrips (>90%) in French Polynesia representing a high diversity of exotic species (leaf, flower, and fungus feeders, and four predatory species) that have successfully infiltrated other island groups in the South Pacific.Survey results and subsequent estimates of thrips species diversity in French Polynesia should be interpreted with caution due to uncontrolled variation in sampling intensity that was affected by survey duration, time of year, and visitation frequency to islands.
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ItemThe Reptiles of Nauru.(Honolulu, University of Hawaii Press, 2008-10)Eleven species of reptiles are reported from Nauru in the first systematic treatment of the herpetofauna. Four of the species are marine; the seven others include six lizards (four geckos, two skinks) and one snake. Gehyra mutilata (Wiegman), G. oceanica (Lesson), Pelamis platura (Linnaeus), and Ramphotyphlops braminus (Daudin) are recorded on Nauru for the first time. With the exception of Emoia arnoensis Brown & Marshall, which is endemic to eastern Micronesia, the herpetofauna consists of species that range widely among the west-central Pacific Ocean islands. The only known record of E. arnoensis from Chuuk possibly is based on a misassigned locality, in which case the range of the species would be limited to the Marshall Islands, Nauru, and Kosrae. There is no evidence to suggest that habitat modification on Nauru stemming largely from more than a century of phosphate mining has reduced the number of reptile species.
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ItemFirst Records of Butterflies (Lepidoptera) from the Republic of Nauru.(Honolulu, University of Hawaii Press, 2008-10)Four species of butterflies are reported from Nauru for the first time and as first records of butterflies from the island republic. None is endemic. Three of the four species are widespread in Oceania: Badamia exclamationis (Fabricius), Danaeus plexippus (Linnaeus), and Hypolimnas bolina (Linnaeus). The other, Petrelaea tombugensis (Ro¨ ber), belongs to a genus that also is widespread in the Pacific. The small number of widespread species found on Nauru is comparable with the situation encountered on other small, remote, low-lying Pacific islands.