tion. Highest organic phosphoi-us values are 

 found in the surface waters in all sections. The 

 mean value from section to section shows only 

 limited variation, the most marked change occur- 

 ring in sections E and F. It is possible that the 

 decrease there from the level of organic phos- 

 phorus observed in all other sections represents 

 some local excess in land runoff or drainage. No 

 noticeable difference is seen in Ungava Bay or 

 Hudson Strait from values along the Labrador 

 and Baffin Island coast. The coastal concentra- 

 tions of mean organic phosphoi-us are somewhat 

 in excess of values reported for the full section 

 across the Labrador Sea to Greenland. They are 

 less than obsei-vations of 1964 in the area of Kane 

 Basin and Smith Somid. 



Vaccaro and Eyther (1960) have pointed out 

 that high concentrations of nitrite-nitrogen in nat- 

 ural waters mark locations where important bio- 

 logically induced changes in combined nitrogen 

 are progressing. The assimilation of nitrate- 

 nitrogen by marine phytoplankton is often accom- 

 panied by the production of significant amounts 

 of extracellular nitrite. Increasing concentra- 

 tions of nitrite can be expected in the upper layers 

 of the ocean when an adequate standing crop of 

 phytoplankton is present and an excess of nitrate 

 is available. Such conditions are characteristic 

 of the summer season in tlie Labrador Sea. The 

 nitrite-nitrogen distributions shown in figure 1 in- 

 dicate that this biological activity is concentrated 

 in surface waters off the continental slielf and sea- 

 ward of the continental slope. This is the same 

 pattern as obtained in previous yeare in the Labra- 

 dor Sea (see Corwin and McGill, 1963). In the 

 absence of other data, this distribution pattern 

 can serve as an indication of the relative produc- 

 tion in these coastal sections. Hopefully, direct 

 measurements will be attempted in the future and 

 the relation of biological and cliemical parameters 

 made more evident for this region. 



Nutrient distribution patterns can also be ex- 

 amined for indication of local currents and water 

 masses. In general, the distribution of phosphate, 

 nitrate, and silicate is consistent with the pattern 

 of surface currents given by Dunbar (1951) . This 

 is particularly true in the Hudson Strait area, 

 where a segment of the Labrador Current entei-s 

 along the Baffin Island coast and an outflow to 

 the Labrador Sea occupies the area near the Que- 

 bec coast. Such a pattern is indicated by the nu- 

 trients in section D. This circulation has given 



38 



evidence in the past of an increased Atlantic influ- 

 ence from 1930 to 1948, as demonstrated by both 

 physical and biological criteria (Dunbar, 1951). 

 Increased penetration by Atlantic water would 

 tend to raise the nutrient levels slightly and such 

 exchange might represent one factor in long-term 

 budgets for the area. The nutrient quantities 

 would also be involved in any "feedback" mecha- 

 nism as proposed by Dunbar (1951) regulating 

 water balance between parts of the Arctic Basin 

 and the Labrador Sea. 



The general pattern of distribution in the coastal 

 sections in the Labrador Sea suggests a phenom- 

 enon analogous to the i^ersistence of "winter wa- 

 ter" on the continental shelf in temperate latitudes 

 (Ketchum and Corwin, 1963). Observations for 

 other ijeriods of the year are needed to detail the 

 sequence of changes taking place on the conti- 

 nental shelf. The available nutrient observations 

 indicate a distinct change between onshore and off- 

 shore water but give only limited details to char- 

 acterize the circulation. Russian observations on 

 zooplankton populations suggest some systematic 

 shift of boreal and warm water forms by season 

 (Vladimirskaya, 1965), but agree that the higher 

 biomass is found in the boreal fauna. 



BIBLIOGRAPHY 



Armstrong, F. A. J. 1965. Phosphoru.s. In: Riley and 

 Skirrow, Ed. Chemical Oceanography. Vol. 1. Acade- 

 mic Press, New York 323-364. 



Corwin, Nathaniel and D. A. McGill. 1963. Nutrient 

 Distribution in the Labrador Sea and Baffin Bay. U.S. 

 Coast Guard Bull. 48 : 79-94. 



Dunbar, M. J. 1951. Eastern Artie Waters. Fish. Res. 

 Bd., Canada Bull. No. 88, 131 pp. 



Ketchum, B. H., R. F. Vaccaro, and N. Corwin. 195S. 

 The annual cycle of [iho-sphorus and nitrogen in New- 

 England coastal water.s. Jour. Mar. Res. 17 : 283-301. 



Ketchum, B. H. and N. Corwin. 1963. The persistence 

 of "winter" water on the continental shelf south of Long 

 Island, N.Y. Limnol. and Oceanogr. 9(4) : 467-47.5. 



McGill, D. A. and N. Corwin. 1965. The distribution of 

 nutrients in the I^brador Sea, summer 1964. U.S. 

 . Coast Guard Oceanographic Report No. 10 (CG 373- 

 10) : 25-33. 



Riley, G. A. and S. A. M. Conover. 19.56. Oceanography 

 of Long Island Sound, 1952-1954. III. Chemical Ocean- 

 ography. Bull. Bingham Oceanogr. Coll. 15 : 47-61. 



Simpson, G. G., A. Roe, and R. G. Levvontin. 19C0. Quan- 

 titative Zoology Rev. Ed. Harcourt, Brace and Co. New 

 York, 440 pp. 



