NO. 9 MARINE INVERTEBRATES, ALASKA — MacGINITIE VJ 



the current run out only at Eluitkak Pass? Although each year the 

 Arctic Contractors cut a channel through the mainland sandspit near 

 the west end of Elson Lagoon almost directly opposite Eluitkak Pass, 

 this channel (see F , fig. i) soon fills in. 



Currents are important to the animals of the ocean because they 

 have a great efifect on the bottom. If there is little current there is 

 mud ; if the current is strong, there is rubble. Each of these bottoms 

 supports a different fauna. The entire bottom has ice-borne gravel and 

 boulders, but only where there are strong currents are the gravel and 

 stones bared so that sessile animals may attach to them. 



Currents are also of importance in distributing larvae, though there 

 is reason to believe that they play a less important role in distribution 

 in the Arctic than elsewhere. Evidence for this belief will be discussed 

 under "Distribution." 



The possibility of a correlation between currents and weather also 

 exists. 



TEMPERATURE (OCEAN) 



Daily surface temperatures were kept from July 12 to October 8, 

 1948, and from July i, 1949, to September i, 1950. During this time 

 the extremes were a low of — 1.8° C. and a high of 7.2° C. (the latter 

 for only a few hours on August 17, 1949), a difference of 9° C. While 

 the ice was out these temperatures were taken from shore by using a 

 long-handled dipper, but during the winter they were taken through 

 a hole in the ice. The water in the hole was always stirred up from 

 below to get the temperature of the water under the ice or, during 

 melting in spring, by taking water from 10 feet below the surface in 

 order to avoid the fresh water. All deep recording thermometers and 

 bathythermograph records show the ocean water below 100 feet to 

 approximate 0.0° C. 



The Bering Sea is somewhat warmer than the Chukchi Sea, and 

 it is possible that currents from the Chukchi may affect the tempera- 

 tures at Barrow from year to year, but much more work is necessary 

 to establish any such effects. 



In his report Dall (1882) gives the average month-by-month tem- 

 perature of the ocean water at St. Michael in Norton Sound. Be- 

 tween October and July this varied from 0.0° to 1.7° C, but the 

 average for July was 13.3° C, for August 13.4° C, and September 

 9.8° C. It would be expected that these high summer temperatures 

 would affect the Point Barrow region, but there was no warming of 

 the waters there for the 3- or 4-month period. It is possible that most 



