Biogenic Hydrocarbons in Intertidal Communities

Zsolnay, Adam; Maynard, Nancy; Gebelein, Conrad

The biogenic hydrocarbon content was monitored from October 1974 through April 1976 at six different sites on Bermuda. Organisms from both the intertidal area and from tide pools were collected. Samples were extracted with Sohxleth, saponified, cleaned up with liquid-solid chromatography, and injected into a gas-liquid chromatograph (GLC). Hydrocarbons that produced peaks 011 the GLC that were considerably greater than the general background of petrogenic peaks were considered to be biogenic. A total of 84 samples of macro-algae and algal mats were analyzed. An overall mean of 33.5 11-glg of biogenic hydrocarbons to wet weight of organisms was found. From the invertebrate fauna, a total of 133 samples were taken. The barnacle, Chthamalus stellatus, had the very high mean value of 108.0 11-glg (wet weight). However, the other invertebrates had a significantly lower mean of 10.5 11-glg. It was not yet possible to ascertain from the data whether the fauna was synthesizing its own hydrocarbon material or whether it was simply incorporating the material from its food source. Of the biogenic hydrocarbons, 21 occurred five or more times. Their Kovat's Indices for an OV-101 column are given. N-penadecane and n-heptadecane were the most abundant. Pristane was never present as a possible biogenic compound.