570 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ns 



With a few exceptions during the observed periods, salinity was 

 relatively low (table 2). It seems logical to expect, however, that 

 the salinity of all the lagoons may be subject to greater or lesser 

 variation both throughout the season and from one year to another 

 because of physical factors influenced by the weather and climate 

 of this high latitude region. Strong winds are frequent even in the 

 summer months, resulting in practically no thermal or haline strati- 

 fication and contributing also to an erratic sampling of plankton 

 organisms. Thus, data from one week or year to another are not 

 necessarily sufficient to estimate accurately the quantitative abun- 

 dance of a species or to assume that its absence from a sample means 

 that it was also absent from the lagoon. Records in table 2 should 

 be viewed on the basis of these considerations. 



Johnson found four species of Eurytemora in nine of the lagoons 

 in 1959. Two of these {E. herdmani, E. pacifica) were not found 

 in our collections, but three additional species (E. composita, E. 

 raboti, E. gracilicauda) occurred. E. arctica was not present in 

 the lagoons but was collected in pools, so that eight species of Euryte- 

 mora occur in the coastal area. In order to indicate what is known 

 of the continuity of species composition shown by three years of 

 collecting, Johnson's records for August 1959 are combined here 

 with our records of July 1959 and of 1960-1961 (table 2). 



With two exceptions, collections from the eight lagoons south of 

 Cape Thompson yielded only E. canadensis, usually in association 

 with and in smaller numbers than Limnocalanus johanseni. Both of 

 these species in Alaska occur along the coast in waters ranging from 

 low salinity to fresh, but there are more known records of E. canaden- 

 sis than of L. johanseni in fresh water with associated freshwater 

 calanoid genera such as Heterocope and Diaptomus (literature and 

 Wilson collection). 



Mapsorak Lagoon (Johnson no. 2S) presents a striking example of 

 the temporal nature of the copepod communities that may at times 

 be collected. In 1959, Johnson found nine marine species that he con- 

 sidered as having been "probably only recently recruited from the 

 sea." He describes the lagoon as having "a narrow above-sea-outlet 

 that probably floods with sea water during high storms." That this 

 large assemblage of species probably had been washed into the lagoon 

 from the sea is suggested by the high saUnity and by the fact that 

 none of the species was found in series of samples taken weekly in 

 1960 and 1961. The difference in the species of Eurytemora found in 

 the three years is noteworthy. E. herdmani and E. pacifica, occurring 

 only diu-ing the period of high salinity in 1959, are typical of inshore 

 waters of the Alaskan coast but are not known from fresh waters nor 

 from waters of extremely low salinity. In 1960, relatively low salinity 



