Experiment: Growth rates and percentages of normal versus malformed versus incomplete versus incomplete and malformed coccoliths

The coccolithophore Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler was cultured in natural seawater with the addition of either the microtubule-inhibitor colchicine, the actin-inhibitor cytochalasin B, or the photosynthesis inhibitor 3-(3,4 dichlorophenyl)-1,1-dimethyl-urea (DCMU). Additionally, E. huxleyi was cultured at different light intensities and temperatures. Growth rate was monitored, and coccolith morphology analyzed. While every treatment affected growth rate, the percentage of malformed coccoliths increased with colchicine, cytochalasin B, and at higher than optimal temperature. These results represent the first experimental evidence for the role of microtubules and actin microfilaments in coccolith morphogenesis.

Age, annual coral growth rates and stable isotopes of coral sample Ningaloo

116-year record of coral skeletal delta18O is presented from a colony of Porites lutea from Ningaloo Reef, western Australia. Interannual variability of sea-surface temperatures (SST) inferred from skeletal delta18O is dominated by a 9.5-year period, and may constitute a characteristic signal of the Leeuwin Current. On long-terms coral skeletal delta18O indicates a near-continuous increase of SST at Ningaloo Reef over one century. The skeletal delta18O time series was checked for the presence of seasonal cooling events resulting from major volcanic eruptions. An ~1 °C cooling is evident following the eruption of Pinatubo in 1991, which reproduces the results of previous investigations. However, only weak or no signals can be related to the eruptions of Krakatau (1883) and Agung (1963).