Chapter 9 - Interstitial Ecology

Abstract

Sandy beaches provide ideal pore space for the development of rich interstitial faunas dominated by bacteria, protozoans, and meiofauna. These organisms generally fall in two size categories, one small enough to attach to sand grains and the other able to move between grains. In beaches of fine sand, low wave energy, and high organic input, reduced conditions occur: oxygen is limited, steep vertical chemical gradients occur, and the fauna is concentrated in the surface oxygenated layers. In beaches of coarse sand, high wave energy, and low organic input, the sediment body is vigorously flushed with water, well drained, and oxygenated and, with little vertical chemical gradation, it has organisms extending deep into the sediment. Distribution of meiofauna within the sediment body and temporal fluctuations in their distribution and abundance are considered. The prime function of the interstitial system is the processing of organic materials flushed into the sand and returning the inorganic nutrients to the sea.