Honors Projects for Marine Biology
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ItemComparison of normal and abnormal coral tissue using microskeletal traits in massive Porites(University of Hawaii at Manoa, 2016-05)Massive Porites evermanni and P. lobata colonies in Hawai‘i have historically been observed with demarcated and raised growth anomalies (GAs). Following Hawai‘i’s mass coral bleaching event in September 2014, growth anomalies on P. evermanni and P. lobata colonies in Lanikai became more pronounced. Growth anomalies appear as noticeable masses of enlarged skeleton and tissue with larger and fewer polyps compared to the adjacent normal tissue. Some corallites in the growth anomaly region even contain additional septa. The purpose of this study was to measure corallite size in normal tissue and growth anomaly tissue. P. evermanni and P. lobata skeletons collected in Lanikai were photographed at 18x using a Nikon Coolpix 4500 attached to a stereo microscope. Ten corallites were measured from each sample using 24 X-Y coordinates mapped on landmark skeletal structures relating to septal length and overall corallite size. The ten sets of 24 coordinates were then averaged to obtain the best representation of corallite size for the sample. The morphometrics of the normal skeletons and the GA skeletons were compared using a principle component analysis and a stepwise discriminant analysis. The P. evermanni jackknifed classification matrix correctly classified 71% of GA samples and 84% of normal samples. The P. lobata jackknifed classification matrix correctly classified 77% of GA samples and 87% of normal samples. Results indicate that corallite structures appear to differ between normal and growth anomaly Porites species samples. Future studies should look at how the presence of growth anomalies affects overall colony growth and reproduction.
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ItemMethod Development: Isolating Microplastics from Copepods in the Ala Wai Canal(University of Hawaii at Manoa, 2016-12)Microplastics are less than 5 mm in size (Zarfl & Matthies, 2010) and originate from the breakdown of larger plastics, cosmetic scrubbers, synthetic fibers, and air-blasting (Cole et al., 2011). Past studies have indicated a concern for bioaccumulation of microplastics in the food chain (Cole et al., 2011; Desforges et al., 2015; Zarfl & Matthies, 2010), but no published data testing this hypothesis has appeared in the literature. Therefore, the focus of this project was on developing methodologies to identify whether or not microplastics exist in the Ala Wai Canal and if they are consequently available and consumed by the canal’s copepods. This study analyzed the efficiency of methods to determine copepod ingestion of microplastics less than 1 mm in size. Results indicated that plankton tows were the most efficient method of collecting copepods and microplastics, that digestions were not very effective, and that a baseline understanding for the features and properties of microplastics less than 1 mm in size still requires testing in order to isolate microplastics from copepods in their natural environments. In conclusion, further baseline studies and knowledge needs to be acquired before it can be determined whether or not microplastics are biologically available to zooplankton, and if bioaccumulation occurs up the food chain.
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ItemCoral reproduction after a bleaching event: Is sexual or asexual reproduction more common? A genetic study of Acropora hyacinthus(University of Hawaii at Manoa, 2015-12)Coral can use a variety of modes of reproduction including sexual and asexual, or both. The mode or degree of asexual reproduction can have significant impacts on the genetic variation and long term stability of a coral reef. A genetic study reveals that in Palau the coral Acropora hyacinthus does not rely on asexual reproduction as a means of recovery after a mortality event, evidenced by the absence of clonal colonies. Microsatellites in the nuclear DNA of coral tissue were sequenced in order to identify clones in the population by comparing microsatellite lengths. Using microsatellite sequences to compare genotypes is a novel approach since traditional studies do not analyze the actual DNA sequences, but rather obtain the total length of the PCR product for sample comparison. Sequencing amplified microsatellite DNA has the potential to increase the accuracy of microsatellite studies, and allows for a more in depth analysis of the genetic composition of these corals. To generate genotypes based on DNA sequences, an analytical pipeline was developed to identify, isolate, and compare microsatellites. Two methods for microsatellite identification were applied and compared to determine which was more efficient with a high level of accuracy, one by hand and the other an automated process. Apart from comparing methods, this research aimed to connect the mode of reproduction after a mortality event to a potential management strategy. Protection should be increased around the coral reefs with a high occurrence of spawning corals to protect the progeny and allow for reef recovery
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ItemIdentification of the molecular components of a putative Tigriopus californicus (Crustacea, Copepoda) circadian clock – a potential model for investigating the influences of anthropogenic light pollution on circadian behavior in an intertidal marine invertebrate(University of Hawaii at Manoa, 2014-09-26)Copepods of the genus Tigriopus have been proposed as marine models for investigations of environmental perturbation. One rapidly increasing anthropogenic stressor for intertidal organisms is light pollution. Given the sensitivity of circadian rhythms to exogenous light, the genes/proteins of a Tigriopus circadian pacemaker represent a potential system for investigating the influences of artificial light sources on circadian behavior in an intertidal species. Here, the molecular components of a putative Tigriopus californicus circadian clock were identified using publicly accessible transcriptome data; the recently deduced circadian proteins of the copepod Calanus finmarchicus were used as a reference. Transcripts encoding homologs of all commonly recognized ancestral arthropod core clock proteins were identified (i.e. CLOCK, CRYPTOCHROME 2, CYCLE, PERIOD and TIMELESS), as were ones encoding proteins likely to modulate the core clock (i.e. CASEIN KINASE II, CLOCKWORK ORANGE, DOUBLETIME, PROTEIN PHOSPHATASE 1, PROTEIN PHOSPHATASE 2A, SHAGGY, SUPERNUMERARY LIMBS and VRILLE) or to act as inputs to it (i.e. CRYPTOCHROME 1). PAR DOMAIN PROTEIN 1ε was the only circadian-associated protein not identified in Tigriopus; it appears absent in Calanus too. These data represent just the third full set of molecular components for a crustacean circadian pacemaker (Daphnia pulex and C. finmarchicus previously), and only the second obtained from transcribed sequences (C. finmarchicus previously). Given Tigriopus’ proposed status as a model for investigating the influences of anthropogenic stressors in the marine environment, these data provide the first suite of gene/protein targets for understanding how light pollution may influence circadian physiology and behavior in an intertidal organism.
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ItemEnergetics of the Deep-Water Bluntnose Sixgill Shark, Hexanchus griseus: Enzyme Activity as an Indicator for Metabolic Rate(University of Hawaii at Manoa, 2014-09-26)A species’ metabolic rate can be used to elucidate life history characteristics, such as locomotive capacity, growth rate, sexual maturity, and ecological role. Utilizing metabolic rates is vital in instances where direct observations of these traits are not easily obtained, such as with deep-water species. Measuring species’ enzyme activity levels provides a proxy for metabolic rate. We determined metabolic enzyme activity levels in the white muscle (WM) of the deep-water bluntnose sixgill shark (Hexanchus griseus) , which is believed to be an apex predator and scavenger in deep-sea ecosystems, as well as 5 other Hawai’ i shark species, from both shallow and deep environments (Galeocerdo cuvier, Isurus oxyrinchus, Squalus mitsukurii, Echinorhinus cookei, and Carcharhinus plumbeus). Animals were caught off of Oahu and biopsied for white muscle, which is responsible for burst locomotion used during predator-prey interactions. Assays were conducted on four key metabolic enzymes: Citrate Synthase, Pyruvate Kinase, Lactate Dehydrogenase, and Malate Dehydrogenase. Enzyme activities derived from this study were compared with WM metabolic data from previous studies in order to evaluate similarities and differences between H. griseus and other elasmobranch species, as well as trends in WM metabolic data for elasmobranchs. Our results showed that H. griseus exhibits significantly lower WM metabolic rates than the other species in this study, but appears similar to the WM metabolic rates of Somniosus pacificus , indicating similarities in ecological strategies between these two large deep-water species. Furthermore, we noted a general decrease in WM metabolic activity with depth, which further indicates differences between shallow- and deep-water elasmobranch burst locomotive capacity and ecological strategies
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ItemAnalyzing Changes to Coral Health and Metabolic Activity in an Oxygen Depauperate Environment(University of Hawaii at Manoa, 2013-07-16)Scleractinian corals play a critical role in marine ecosystems by providing essential structure for coral reef habitats. However, recent investigations have found an alarming increase in coral death as the result of stressors, which threaten the general health of tropical coastal environments. Of particular interest is the effect of oxygen deprivation on the health of Hawaiian corals through the analysis of anaerobic respiration, as it is poorly documented. The fast-paced growth of Gracilaria salicornia gives this alga the ability to overgrow coral heads, restricting water flow and light, thereby smothering corals. Field data shows hypoxic conditions (DO2 < 2 mg/L) occurring underneath algal mats at night, and concurrent bleaching and partial tissue loss of shaded corals. This study aims to simulate hypoxia in a laboratory setting in order to limit the effect of environmental variables on coral health. Analyses of stress in corals due to anoxia were accomplished through the quantification lactate dehydrogenase and opine dehydrogenase activities. Treatment corals were found to exhibit almost complete tissue loss and severe bleaching with increasing exposure duration to hypoxia. Conversely, control corals were found to exhibit little to no tissue loss or bleaching throughout the treatment cycle. Treatment corals also experienced significant increases in alanopine dehydrogenase and strombine dehydrogenase activity, while no octopine dehydrogenase or lactate dehydrogenase activity was detected. These findings suggest anoxia as a major source of increased coral stress, which occur in response to hypoxic conditions, such as invasive algae mat smothering, and provide insight into coral tolerance to controlled extremely low-oxygen environments.