Diversity and similarity of benthic fauna off Oregon

Graduation date: 1970Samples of benthic organisms off the coast of Oregon, taken\ud from depths varying from 50 to 2900 meters, have been analyzed in\ud terms of diversity at a given station, and similarity and ecological\ud distance to other stations. Estimates of epifauna abundance were\ud also made. In the analysis an important distinction is made between\ud diversity, abundance, and variety indices; the three measures are\ud considered independent pieces of information relevant to the ecological\ud structure of the population of interest.\ud Two types of sampling gear were used. Large epifauna were\ud sampled with a beam trawl. Polychaetous infauna were sampled with\ud an anchor-box dredge.\ud The diversity index chosen is Simpson's index; the measures\ud of similarity and ecological distance are related. These measures are preferred because of their ease in calculation and basic simplicity.\ud In addition these measures may be interpreted as estimates of well-defined\ud population parameters (as Simpson has pointed out) which have\ud straightforward probabilistic interpretation.\ud A valid measure of diversity is one piece of relevant information\ud necessary for elucidating the sufficient parameters of ecological\ud systems. Therefore the methodology presented has broad application\ud to studies of population structure