Pacific Science, Volume 62, Number 4, 2008

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    First Record of a Pearlfish, Carapus mourlani, Inhabiting the Aplysiid Opisthobranch Mollusc Dolabella auricularia.
    (Honolulu, University of Hawaii Press, 2008-10) Glynn, Peter W. ; Enochs, Ian C. ; McCosker, John E. ; Graefe, Abigail N.
    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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    Seasonal Occurrence and Aggregation Behavior of the Sea Urchin Astropyga pulvinata (Echinodermata: Echinoidea) in Bahia Culebra, Costa Rica
    (Honolulu, University of Hawaii Press, 2008-10) Alvarado, Juan Jose
    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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    Acropora (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) Kenyon, Jean C.
    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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    Demographic Parameters of Yellowfin Croaker, Umbrina roncador (Perciformes: Sciaenidae), from the Southern California Bight.
    (Honolulu, University of Hawaii Press, 2008-10) Pondella II, Daniel J. ; Froeschke, John T. ; Wetmore, Lynne S. ; Miller, Eric ; Valle, Charles F. ; Medeiros, Lea
    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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    Maximum Annually Recurring Wave Heights in Hawai‘i.
    (Honolulu, University of Hawaii Press, 2008-10) Vitousek, Sean ; Fletcher, Charles H.
    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.