Major Taxonomic Groups Of Macrobenthos In 

 Disko Bay And Several West Greenland Fjords 



Roger B. Theroux ^ 



INTRODUCTION 



Maci'obenthic organisms were sampled during 

 the Glacier and Oceanographic Survey cruise of 

 the I'SrCxC' EASTWINI) to AVest Greenland, 

 18 July to 8 August, 1968. The collections were 

 made to provide information about the fauna of 

 West Greenland, including (1) the difference, if 

 any, in the composition of the fauna of Disko 

 Bay and the inshore sides of sills at the mouth 

 of fjords; ('2) the types of organisms inhabiting 

 the sediments within the fjords; and (3) the fau- 

 nal composition of the deep basins of the fjords, 

 especially tliose where oxygen levels might be 

 low. This preliminary report lists the major 

 groups of organisms collected and the types of 

 sediments in wliich they occurred. 



SAMPLING PROCEDURE 



Macrobenthic organisms were taken at 13 of 

 the 21 stations at wiiich bottom samples were 

 collected (tig. 1) ; station data and other physical 

 features are given in Table I. Water depths 

 ranged from 72 to 7.50 meters. A Van Veen grab 

 (().2ni-) was used at 10 stations and a Dietz- 

 Lafond sampler (O.Olm^) was used at 11. All of 

 the Van Veen, but only 3 of tlie Dietz-Lafond 

 samples (stations 3, 14, and 21) were processed 

 for macrobenthos; tlie remaining 8 Dietz-Lafond 

 collections provided only enough material for 

 sediment samples. (The samplers are illustrated 

 in figs. 2 and 3). Macrobenthic organisms were 

 present in all of tlie processed samples. 



The macrobenthos was washed out of the sedi- 

 ments tlirough a 1-millimeter mesh screen, pre- 

 served in a 10 percent buffered formalin solution, 

 and later sorted and identified to major taxonomic 

 groups. 



At each station a 1-liter sediment sample was 



• U.S. Department of the Interior, Bureau of Commer- 

 cial Fi.sherles Biological Laboratory, Woods Hole, Mass. 



retained when the total volume of the sample 

 permitted (a smaller amount was removed from 

 small samples), and stored, without further treat- 

 ment, in plastic containers. 



TAXONS AND SIZES OF 

 MACROBENTHOS COLLECTED 



Tlie macrobenthic organisms of Disko Bay 

 and the West Greenland fjords are typical of 

 those found in soft muddy ocean bottoms of 

 northern latitudes. Among the organisms in the 

 collections were mud stars {Ctenodiscus crinpa- 

 txin), errant and sedentary polychaete annelids 

 {Nephtyn, Onuphis, Maldamdae, Chaetopteridae, 

 Serpulidae, Sabellidae), sea urchins {Strongylo- 

 cenfrofys), britt'e stars (Ophiuroidea), sea cu- 

 cumbers (Holotliuroidea), mud- and sand-dwell- 

 ing bivalves (Astarte, Cuspidaria, Hiatella, 

 Macoma. NucuUu Nticulana. Thyasira), snails 

 (Naticidae), and moss animals (Bryozoa). Some 

 of the organisms are illustrated in figure 4. 



In terms of numbers of individuals, polychaete 

 annelids were the most abundant group of or- 

 ganisms in the collections. They occurred at all 

 stations sampled. The bryozoans were the next 

 most abundant group, followed by the molluscs 

 and ecliinodei-nis. Crustaceans made up only a 

 small percentage of the total macrobenthic fauna. 

 Table II shows the distril)ution and occurrence 

 of tlie major taxonomic groups. 



Most of the macrobenthic organisms were 5 to 

 20 millimeters long; only a few were larger. The 

 exceptions included Bryozoa colonies (some were 

 3 to 6 centimeters wide) ; two mud stars, Cteno- 

 dixcus crispatuH, about 6 centimeters in diameter; 

 and one large mud worm, Nephtyv. longer than 

 12 centimeters (most of the other annelids were 

 less than 1 centimeter long). Living molluscs 

 were generally less tlian 5 millimeters long, but 



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