Jack Jeffrey: Photo Resource Hawaii 



A red-footed booby, left, perches in a tree on Kure Atoll In Hawaii. Below. 

 False-color satellite images show the changing distribution of microscopic 

 plant life, or phytoplankton, in the northern Pacific. Green indicates a high 

 phytoplankton concentration; blue, a low one. The white patches are the main 

 Hawaiian Islands, and the black patches are clouds. A drop in productivity to 

 the north of the main Hawaiian Islands is evident between the first quarter 

 of 1982. below left, and the same period in 1986, below right. 



levels characterized by a weak Aleutian 

 low and weak winds. 



I left the conference with a new insight 

 into the changes in the marine community 

 of the northwestern Hawaiian Islands. 

 Since I had no biological data prior to the 

 1980s, I had assumed that the level of pro- 

 ductivity in the early 1980s was the norm 

 and that the recent drop signaled some- 

 thing unusual — a reasonable assumption 

 given that the commercial lobster fishery 

 had only been in operation since 1980, 

 when lobsters were plentiful. Having 

 leamed that the early 1980s were charac- 

 terized by abnormal climate pattems, I re- 

 alized that the opposite was more likely. 

 What originally looked like an ecological 

 disaster, might be only a return to the usual 

 population levels. The challenge that re- 

 mained, however, was to determine if the 

 atmospheric changes across the northern 

 Pacific were reflected by equally dramatic 

 changes in the ocean — changes that could 

 effect an entire ecosystem. 



Back in Hawaii, I went to see Gary 

 Mitchum, a physical oceanographer at the 

 University of Hawaii. A year before, 

 Mitchum had shown me how a shift in cur- 

 rent could have caused a change in lobster 

 distribution, and he thought that his help 

 entitled him to some of the lobsters caught 

 on our research cruises. When I entered 

 his, office, he reminded me that he not re- 



ceived a single lobster for his trouble. 

 Once I explained the reason for my visit, 

 however, Mitchum forgot about free lob- 

 sters and became intrigued with the idea 

 that a decade of unusually strong Aleutian 

 lows could alter the ocean enough to have 

 drastic effects on marine life. He agreed to 

 sift through the oceanographic data to see 

 if he could find any evidence of such a 

 connection. 



Several weeks later, Mitchum came to 

 see me and was quite pleased with what he 

 had found: several large-scale features of 

 the ocean reflected the changing intensity 

 and position of the Aleutian low. The 

 match was good enough to convince him 

 that the link between atmosphere and 

 ocean was real. During the last decade, 

 tide gauges recorded exceptionally high 

 sea levels over the central and eastern 

 North Pacific during the winter months. 

 The increase, which reached about four 

 inches, was probably caused by an east- 

 ward shift in ocean waters due to the 

 change in wind strength and pattern result- 

 ing from the change in the low-pressure 

 system. At the same time, Mitchum found 

 that water-temperature readings taken 

 from ships showed that from 1977 to 

 1988, the warm surface layer extended 

 much farther down than it did from 1960 

 to 1976 or since 1988. This is evidence 

 that from 1977 to 1988, there was an in- 



crease in the mixing of deep, nutrient-rich 

 waters with nutrient-poor surface waters. 

 Mitchum and I estimated that during this 

 eleven-year period, the deeper mixing 

 brought five times more nutrients into the 

 surface waters than during the period from 

 1960 to 1976 or since 1988. 



As a biologist, I was more excited by 

 Mitchum 's second finding, because it had 

 great consequences for the marine life 

 near the surface. Sun-warmed surface 

 water is less dense and "floats" atop the 

 colder water below. Usually there is very 

 little mixing between the two layers. With- 

 out an influx of nutrients from deeper wa- 

 ters, the growth of phytoplankton near the 

 surface — where the sunlight is — is se- 

 verely limited. The problem is particularly 

 acute in midoceanic regions, such as the 

 waters around Hawaii, where the sea is 

 often described as a desert. Whenever the 

 deeper, nutrient-rich waters are brought to 

 the surface, as in an upwelling system, 

 phytoplankton production soars. This is 

 apparently what happened from 1977 to 

 1988, when more nutrients from deep wa- 

 ters were mixed into surface waters. 



By early 1993, the pieces were all com- 

 ing together. Ed DeMartini had the results 

 of the reef fish survey, which confirmed 

 that the numbers of most species have 

 dropped 30 percent from what they were 

 in the early 1980s. Mei Zhou's analyses of 



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