Composition and Distribution of Macrobenthic Invertebrate Fauna 



MUM6ER OF SAMPLES 



PER UNIT AREA 



( 20' x 20' ) 



• 1 - 2 



• 3-5 



• 6-10 



DEPTH IN METERS 



Figure 2 



Chart showing sampling intensity within each standard unit area (20 min. latitude bv 20 min. longitude). All samples 

 within each unit area have been added to indicate sampling density. 



separate sample. The contents of the sampler were 

 emptied into a bucket or tub calibrated in liters, or 

 directiv into a wash-box (volume measured by means of 

 a calibrated rule) from which two small subsamples 

 were removed prior to washing. One of these subsamples 

 was for meiofauna, and the other for sediment analysis. 

 Total quantity removed ranged from 0.25 to l.O I., 

 depending upon the total volume of material obtained. 

 The quantities of both samples and subsamples were 

 measured and recorded on sample log sheets. Gener- 

 ally, the remaining material was washed through a 1-mm- 

 aperture mesh-sieving screen. Material remaining on the 

 screen after washing, consisting of benthic animals, tubes, 

 shells, shell hash, and coarse sediments, was preserved in a 

 buffered seawater solution of formaldehyde and brought 

 to the laboratory ashore for further processing. 



Laboratory processing involved separating the preserved 

 organisms from the mineral debris, sorting them to major 

 taxonomic groups, identifying them to the lowest practi- 

 cable taxonomic level, counting, and weighing. Weights 

 are damp formalin weight, the "rough weight" of Petersen 



(1918), herein referred to as wet weight inasmuch as the 

 superficial fluid on the specimens was removed by blot- 

 ting before being weighed on a Mettler precision balance 

 to the nearest 0.01 g. Weights include shells and skeletal 

 materials that constitute an integral part of the liring 

 animal, i.e. shells of liring mollusks, brachiopods, and 

 skeletal structures of bryozoans, barnacles, and similar 

 organisms. Materials omitted in the weighing procedure 

 were: tubes of polychaetous worms, gastropod and 

 scaphopod shells inhabited by pagurid crabs or sipunculid 

 worms, and other similar nonintegral structures or nonliv- 

 ing animal remains. Counts of the number of specimens 

 were made for all groups. Colonial animals were treated as 

 individuals; that is, one sponge colony, or a colony of 

 bryozoans was each counted as an individual specimen; 

 colonies are much more comparable in size to individuals 

 of noncolonial animals than are the zooids making up the 

 colony. Also, the disparity in size from smallest to largest 

 colonial organisms was only slightly greater than the size 

 differential between small and large individuals of 

 noncolonial species. 



