Browsing by Subject "Reef 42 coral"

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    Spatial variability in the stable isotope and lipid composition of coral tissues (Porites compressa)
    (2008) Hurley, Leah; Pease, Tamara Kaye
    This study investigated the isotopic and lipid class compositions of the coral species Porites compressa and its associated zooxanthellae. It examined whether spatial scales in their variability were linked to environmental factors that may be impacting reefs and affecting their health. Samples were collected from Reef 42 and Coconut Reef within Kaneohe Bay, HI. Coconut Reef has higher turbidity and nutrient loading as well as more riverine input and restricted circulation than Reef 42. At each reef samples were collected according to a spatially nested design that tested for variability between samples at 1 and 4m depths and at ~0.5, 2, 50, 300 and 6,000 m apart. Isotopic analysis showed that there were significant differences in the δ¹³C and δ¹⁵N values of corals and zooxanthellae across all spatial scales examined, except for between samples separated by 300m. Variability exhibited over small spatial scales likely reflects genetic heterogeneity. The isotopic differences in coral tissues that were observed between reefs suggest that they may be of utility in detecting environmental changes in nutrient inputs and light availability. Specifically samples collected from Coconut Reef exhibited enriched δ¹⁵N and depleted δ¹³C values compared to those from Reef 42. These results may be indicative of the increased levels of anthropogenic and terrestrial nutrients present at Coconut Reef. In contrast to the isotopic variability the lipids of both the host tissue and zooxanthellae were fairly homogenous across all spatial scales. These results suggest that corals are capable of maintaining their energy reserves under various levels of nutrient loading and turbidity. They are likely able to do this by increasing the proportion of heterotrophically acquired food in their diet when autotrophy is insufficient to meet their metabolic demands