M.S. - Zoology (Marine Biology)

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Now showing 1 - 7 of 7
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    The Movements of Predatory Reef Fishes in the Molokini Marine Life Conservation District
    ([Honolulu] : [University of Hawaii at Manoa], [May 2016], 2016-05) Filous, Alexander
    Predators play a critical role in maintaining the balance of marine ecosystems and are an important component of Hawaii’s recreational and commercial fisheries. In light of the increasing pressures on these populations in recent decades across the main Hawaiian Islands from both consumptive and non-consumptive resources use, the study of apex predator movements in marine protected areas has become a research priority. To this aim, we used passive acoustic telemetry to investigate the spatial and temporal movement patterns of five apex predators: bluefin trevally (Caranx melampygus), giant trevally (Caranx ignobilis), green jobfish (Aprion virscens), whitetip reef sharks (Triaenodon obesus) and grey reef sharks (Carcharhinus amblyrhynchos) at the 31 ha Molokini Marine Life Conservation District (MLCD) off Maui, Hawaii. The Molokini MLCD is the second most visited MLCD in the State of Hawaii with over 300,000 visitors per year. Our results indicate that residency was variable across species, with bluefin trevally exhibiting the highest residency in the MLCD and green jobfish the lowest. Bluefin trevally showed displacement from critical habitats in the MLCD during peak visitation hours. Long distance movements between the Molokini MLCD and the other islands of the Maui Nui Complex were common for grey reef sharks, giant trevally, and green jobfish. These results indicate that despite its small size, the Molokini MLCD provides a high level of protection to resident species such as bluefin trevally. However, this MLCD is less effective at protecting more mobile apex predators such as green jobfish, grey reef sharks, and giant trevally.
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    Does Chlorophyll-A Turn Up the Volume? Exploring the Relationship between Oceanographic Parameters and Coral Reef Soundscapes
    ([Honolulu] : [University of Hawaii at Manoa], [December 2015], 2015-12) Fisher-Pool, Pollyanna
    Remote coral reefs offer unique opportunities to study marine environments removed from anthropogenic stressors. There is an interest in studying whether coral reef biological activities are influenced by oceanographic variables. Previous work has failed to relate how metrics like chlorophyll-a, sea surface temperature, irradiance, and wave energy flux influence biological signals. With the use of long term passive acoustic monitoring, soundscape components are separated into different frequency bands and the relationships between coral reef soundscapes and oceanographic variables are explored through generalized linear models and generalized additive models. The results elucidate to the usefulness of snapping shrimp as indicators of coral reef health, confirming the association of snapping shrimp acoustic activity in relation to temperature changes and revealing the reaction to changes in chlorophyll-a . This study shows the importance of using multidisciplinary approaches to environmental questions.
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    Environmental surveys reveal diversity in free-living populations of Symbiodinium from Caribbean and Pacific reefs
    ( 2006) Manning, Mackenzie Marie
    The Symbiodinium species complex is genetically and ecologically diverse. Small and large-scale biogeographic distribution patterns reveal that some symbiont types are host specific while others are compatible with a wide range of hosts (Baker and Rowan 1997; LaJeunesse 2002; LaJeunesse et al. 2004; Ulstrup and van Oppen 2003). Observations of natural bleaching patterns, coral-algal associations under different stress regimes, cultured symbionts under different environmental conditions, and symbiont infectivity studies have led investigators to believe that different host-symbiont combinations are possible and can exhibit different tolerances to stress (Baker 200 I; Berkelmans and van Oppen 2006; Glynn 1993; Hoegh-Guldberg and Smith 1989; Hoegh-Guldberg and Fine 2004; Kinzie et al. 2001; Kirk et al. 2005; Robison and Warner 2006; Rodriguez-Lanetty et al. 2004; Rowan et al. 1997). These observations lead to the formulation of the Adaptive Bleaching Hypothesis (ABH), first described by Buddemeier and Fautin (1993). The ABH posits that coral bleaching provides an opportunity for corals to modify their symbiotic communities in response to changing environmental conditions. In this light, bleaching is a way for corals to adapt to such change within an ecologically relevant time scale. This could theoretically be achieved by two mechanisms that are not mutually exclusive. The first mechanism facilitates an exchange of the current, less physiologically tolerant symbiont community for a new community of symbionts acquired from environmental pools that are physiologically better suited to the prevailing conditions ('switching'). The second mechanism results in a rearrangement of the abundance of different types of symbionts already present within the host coral ('shuffling'). There are a number of critical assumptions that must be met in order to accept this hypothesis: I) that multiple types of symbiotic algae exist in nature, 2) that different types of symbionts are characterized by different physiological optima, 3) that corals with new symbiont types exhibit higher resilience in the face of further environmental change, and 4) that a diversity of symbiont types are available and free-living in the environment (i.e. water column and substrates) and can colonize bleached hosts. While the first three assumptions have, or are currently being explored in some detail (see Baker 2001; Kinzie et al. 2001; Savage et al. 2002; LaJeunesse 2004), research regarding the last assumption has been gradual. There is currently very little data on the diversity, spatial distribution, and temporal behavior of Symbiodinium populations free-living in the environment (Kinzie et al. 200 I). Research utilizing experimentally bleached, facultative hosts and aposymbiotic larvae (without symbionts) has shown infection by Symbiodinium when exposed to environmental seawater (Kinzie et al. 2001; Lewis and Coffroth 2004; Thornhill et al. 2006). There are two reports of free-living Symbiodinium being cultured from waters and/or sediments surrounding potential hosts (Carlos et al. 1999; Gou et al. 2003). As new discoveries concerning the ecology, physiology and fitness of the symbiosis are being made, it is becoming increasingly important to fully characterize the availability and diversity of environmental pools of free-living Symbiodinium. We have developed a protocol to explore the diversity of free-living Symbiodinium in seawater and have used it to analyze samples taken from coastal, tropical reef habitats in the Pacific and Caribbean. Using two different molecular markers, one specific to Symbiodinium, we have successfully resolved known Symbiodinium types in these seawater samples, including C3, C15, B1, and D1. We report a number of novel sequence types that have not previously been described. Our results demonstrate the effectiveness of this protocol in examining Symbiodinium diversity across spatial scales and we hope that the broad application of this protocol will provide insight in the temporal and spatial variability and environmental resilience of free-living Symbiodinium populations.
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    Reproductive ecology and distritution of the scleractinian coral Fungia scutaria in Kane‘ohe Bay, O‘ahu, Hawai‘i
    (University of Hawai‘i, Honolulu, 2000-08) Lacks, Amy L.
    In Hawaii, abundance of the scleractinian Fungia scutaria is thought to have been in decline in recent years due to disturbances to Kaneohe Bay, where an unusually dense population exists. This study examines factors that could limit population growth in this coral. Sexual reproduction occurred throughout the summer. Experimental data from sperm dilution studies suggested that eggs must be released within 2m of a spawning male for successful fertilization to occur. Field surveys indicated that many patch reefs exhibited high enough densities to yield successful fertilization. However, since field surveys found that only a small percentage (1 %) of juvenile corals (5 cm in length) resulted from settled larvae, post-fertilization processes may be limiting successful recruitment. Asexual reproduction appears to be dominant, with 70% of corals occurring in close aggregations, and 93% of these in aggregations made up of a single color-morph.
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    Growth Rate of Fungia Scutaria in Kaneohe Bay, Oahu
    ( 2010-04-06T05:12:47Z) Bosch, Herman F.
    The annual growth rate of the solitary coral Fungia scutaria Lamarck was determined by observed increases in skeletal length and width. Growth was followed for periods varying from 7.5 to 9.0 months during 1963 and 1964. Measurements were made in situ at the center of fungid distribution in Kaneohe Bay, Oahu, where there exists an aggregation of Fungia which is atypically dense for the Hawaiian Islands. Although this bay provides a relatively optimal environment for the growth of Fungia, as demonstrated by their abundance and increased rate of growth, variations in growth rate is apparently as erratic here as in other areas. Growth curves, constructed for various arbitrarily selected size-classes of Fungia, confirm earlier observations of greater rates of skeletal growth in the smaller corals. The results of this study indicate the necessity of basing reliable estimates of coral growth rate upon an adequate sampling, taking into account the past history and size of the corals measured.
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    Development Of Mechanosensory Responses In Myelinated Copepods
    ( 2005-08) Funk, Kevin R.
    This thesis will examine the mechanosensory capabilities of juvenile copepods from an essential prey species in the North Atlantic food web, Calanus finmarchicus. An important underlying component of these interactions is myelination of axons associated with decreased response latencies, yet myelination has not been observed in electron micrographs of copepod nauplii. Electrophysiological recordings from juvenile copepods are presented and their analysis found that myelin is consistently present in CII and later copepodite stages (CI copepodids could not be obtained for recording). Two unidirectional mechanosensory units were distinguished in all developmental stages studied using a controlled hydrodynamic stimulus, while a third slower non-mechanosensory unit was observed. Adults were found to be the most sensitive to mechanosensory stimuli, with thresholds of water displacement (not velocity, as reported in other copepods) of less than a nanometer. While copepodids were less sensitive, much longer antenna:prosome ratios were observed in CII copepodids.