Effects of sedimentation on the gorgonian Subergorgia suberosa (Pallas, 1766)
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Effects of oceanic and terrestrial sediment suspensions on the behavioral traits activity, colony expansion, and mucus formation of the gorgonian octocoral Subergorgia suberosa (Pallas, 1766) were studied in the laboratory. Increased sediment concentration significantly changed the logits of activity indices (as colony expansion) and was correlated with decreased activity. For both sources of sediments, the activity index decreased as the concentration of sediment increased. The level of decrease was more significance for terrestrial sediments. The activity index showed no clear time pattern for the control group, but a decrease over time occurred in both sediment treatment groups. Activity change was linearly correlated with exposure time and concentration of terrestrial and ocean sediments. The activity indices of polyps were negatively correlated with the formation of mucus sheets (correlation = −0.536, p = 0.048). For both sources of sediments, the frequency of mucus sheet formation (MSF) increased with sediment concentration. Increases in terrestrial sediment loads resulted in more striking effects. The probability for MSF under different sediment groups at different concentrations over time was modeled by regressions. Frequency of polyp activity is suggested as a suitable biomarker to monitor the effects of sedimentation stress.
KeywordsActivity Index Sediment Concentration Sediment Source Coral Coloni Mucus Secretion
We acknowledge our debt of gratitude for the assistance provided by the technicians from J. S. Hwang’s laboratory for their contribution to the field-sampling program. We are grateful to the National Science Council of Taiwan, ROC (NSC grant No. 97-2621-B-019-004) and the Center of Excellence for Marine Bioenvironment and Biotechnology of National Taiwan Ocean University (99529001A) for financial support to J.S. Hwang.
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