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Author: by Vladimir AVILOV Dr. Sc. (Tech.). and Svetlana AVlLOVA. Dr. Sc. (Biol.). P.P. Shirshov Institute of Oceanology. RAS
In the spring of 1994 we flew from Moscow to Buenos Aires, the Argentine capital. Our destination was Ushuaia, a port on the tip of South America, on Tierra del Fuego. Once there, we boarded the Russian research vessel Akademik Sergei Vavilov for a long transoceanic voyage. But there were actually two such voyages before us.
The very name fired our imagination. Verbally. Tierra del Fuego. "The Land of Fire", a land at the back of beyond! It was autumn there as we landed on that archipelago. Here and there we could see snow-capped mountain peaks. As to vegetation, it was amazingly like ours near Moscow-the same camomiles, daisies, white clover and birch-trees, though stunted. And all that basking in the sun in a warm spell of wonderful autumn weather.
Leaving our gear on board (over 70 kilos), we rushed to see the sights of Ushuaia, the capital of Tierra del Fuego. Although weary because of the jet lag, we were pretty curious. It is a small town, Ushuaia, with its neat and cosy streets flanked by posh mansions, two and three stories high, climbing from the bay up towards the mountains. This port city is a hub of tourist traffic in which our snow-white beauty, the Akademik Sergei Vavilov, must have been playing a leading part-she took wanderlust travelers on arduous voyages to the shores of Antarctica, to its icebergs and penguins...
Early next morning our research ship weighed anchor and started sailing out of the bay. We were fascinated by the thrilling sight beyond: for a time the sky, mountains and water blended into a flaming-red fiery mass, as if the molten sun had engulfed everything.
So we left Tierra del Fuego. We were bound northward: first passed along the eastern coast of Argentina, then across the Atlantic over to the shores of Africa and Europe, and through the Northern and Baltic Seas on to our homeland, Russia. During this voyage we were to make geochemical and biological studies of ocean surface waters, and ascertain their gas composition.
We had done good spadework in the preceding few years. We had evaluated a wealth of evidentiary material obtained by various marine expeditions. We had profiled the typical distribution patterns of biologically active substances in the Atlantic Ocean and identified zones depending on the ecological situation there. Now we were to cross many of those zones. We were intrigued about whether the boundaries between them were still the same, and how the surface waters had changed in the meantime. Those were no idle questions: even though the condition of ocean water is determined by global processes that ensure the stability of pelagic ecosystems, the negative effects of anthropogenic modification could not be discounted either.
Thus our job was to study the biological structure of sea water as well as the flows of substances and energy there. The snag was how to tell apart the dead from the living microorganisms and evaluate the vital (biological) activity of the latter according to quantitative characteristics. We had developed methods allowing to determine the key indices: concentration of adenosine triphosphate (ATP) and certain hydrolytic enzymes (including alkali phosphomonoesterase, APase), as well as the concentration of the gaseous components of fluids(*).
World oceanology knows but few instances of such comprehensive studies which are of the paramount importance- not only in terms of scientific data alone but also with an eye to oil and gas prospecting, ecological zoning and monitoring, and in improving the kit of instruments. And in many other areas as well.
We studied the gas and biochemical composition of the surface waters of the Atlantic and then of the Northern and Baltic seas by taking samples aboard, with one exception only, when we were probing the Cape Verde trough well-nigh in the middle of the Atlantic to a depth of 3,000 meters, the job that took us four hours. We had a good chance to test our new integrating bathometer that harvests integral samples of water and collects circumstantial data. And it was proven effective in all that. It performed particularly well within our bathyscaph and enabled us to trace changes in the concentration of ATP and in the biomass of active living microorganisms (BALM)- the miniscule things 0.4-200 um in size-in 200 m water layers. The
* See: V. Avilov and S. Avilova, "The Mystery of Black Sea Sediments", Science in Russia, No. 2, 1995. -Ed.
concentrations ranged 110 to 210 ng ATP per I-1, and 28 to 52 ug C per I-1, respectively. Samples taken in surface waters and to a depth of 700-900 m showed two maxima of nearly equal concentrations of ATP and BALM; yet another, lower indicator was obtained in water layers 2,800-3,000 m below the surface. But the lowest concentration of biologically active substances, hydrolytic enzymes among them, was registered at a depth of 400-600 m. As to hydrocarbon gases, their concentration was at the level of background values to a depth of 200 meters, which means they have no effect on biochemical processes there.
An analysis of the data obtained on our voyage shows that the biological activity of the surface waters in the Atlantic-from the southern extremity of the American continent up to the Canary Islands-conformed by and large to normal ecological values (true, it was slightly above the norm in some regions). However, in the Cape Verde trough, to a depth of 400 to 600 m, the biomass of picoplankton, a community of tiny microorganisms (0.12-0.4 um), exceeded the total mass of larger microorganisms (0.4-200 urn) that are usually studied in oceanology by 10 to 102. The overall mass of picoplankton was found to be 2,250 ug C I-1, which attests to enhanced biological activity within the ocean. So we could see signs of eutrophication (plankton waterbloom) of deep ocean waters, a trend that may impact someday the gene pool of the planet's microorganisms.
Having identified regions characterized by enhanced (versus background) biological activity in the Atlantic, we saw that the level of this activity was different in origin. On Argentina's southern shelf it is intensified by fluids of hydrocarbon gases rising from sea floor sediments. Water samples showed high concentrations of methane and the highest concentration of ethane we had ever encountered throughout our expedition; both indicated oil and gas shows. Farther north the situation changed: the fresh waters of the Parana and the Uruguay, both flowing into the Plata River, account for heightened biological activity in the northern part of the shelf. The effect is felt in the open ocean hundreds of miles away.
We discovered a highly interesting zone near the equator, above the faults Romansch and Sao Paulo of the North Atlantic Ridge. In the surface waters we detected gaseous fluids rising from the bowels of the earth with aggregate
concentration of helium and hydrogen attaining rather high values-2.1 ? 10-3 ml l-1. These fluids stimulate the proliferation of microorganisms there, hence the excessive biological activity of the water. The ATP and BALM concentrations there exceed several fold the background level, and the concentration of hydrolytic enzymes was found to be higher there too.
Along sea lanes we registered signs of technogenic effects on the surface waters. But here closer investigations of both surface and deep waters are needed for assessing the ecological status of the Atlantic Ocean. The smaller microorganisms, responsible for the waterbloom of ocean depths, ought to be taken into account thereby...
Our transatlantic voyage over, we plunged into our routine research chores, sorting and evaluating the data we brought home. We could never imagine that, in a year or so, we would fly to Tierra del Fuego again to embark on another long voyage. That was something in the realm of dreams. And yet these dreams came true, and we were all set for another odyssey. This venture became possible thanks to aid and assistance from Dr. Martha Shuare, the Argentine Consul on Science and Technology in Moscow, from Juan Carlos Pecoroff, president of the MATIMPORT S.A. firm in Buenos Aires, who agreed to finance our expedition, and from our Institute, of course, that supported us in our undertaking.
And so in 1995 we landed in Buenos Aires again. Our kit now approached 100 kilos, for we had thrown in some other instruments. After a few days of talks with our Argentine colleagues we
moved to the seaport of Ushuaia where the research vessel Akademik Joffe was at anchor.
This time our voyage took in the Pacific-first we hugged South America's western coast (Chile, Ecuador) and then, through the Panama Canal, entered the Atlantic which we were to cross all the way through to the Northern and Baltic Seas, as we had done on our previous expedition. The Akademik Joffe sailed clear of South America's tip in between the isles of Tierra del Fuego. It was a long and hard passage: a very strong current in the narrow straits kept all the crew on tenterhooks, and the captain could not leave his bridge on the deck even for a moment. We feasted our eyes on the shores nearby and got ready for the work. At long last our ship was on the high seas in the Pacific...
Moving along South America's western shores, we could see that the concentration of ATP and hydrolytic enzymes in surface waters was rather high. The resulting intensive proliferation of microorganisms (their biomass equal to 500 ug C I-1 almost everywhere) is due to natural causes. One such factor are the flows of substances and energy generated by the cold waters of the Peruvian stream rich in bio-genes (phosphorus, nitrogen), and by upwellings, with deep waters rising to the surface.
The ATP concentration proved anomalously high (up to 5,900 ng 1-1) in a water area between 18 and 7 S, where the Peruvian up-welling is at work. The "spotted" biological structure of the ocean surface due to the numerous local upwellings of cold water is responsible for steep jumps in the ATP concentration and in other biochemical characteristics. Our surveys detected local upwellings much to the south of this zone, that is at 35 31' and 28 50' S, as shown by the high concentrations of ATP registered there for the first time.
Meanwhile our research ship Akademik Joffe kept moving northward. Off the coasts of Ecuador and Central America we defined the boundaries of water areas noted for heightened and high biological activity. We found them not to be so large as before.
Through the Panama Canal we crossed into the Caribbean. In this sea, which is at the source of the Gulf Stream, and way over to the southeast, above the Gibbs fault of the North Atlantic Ridge, the geoecological condition of surface waters was found to be on a par with the background. And
since northeast of the fault we registered an enhanced concentration of biologically active substances, it could be inferred that the background zone had shifted 10 to 15 degrees to the south. Sailing across the Gulf Stream, where water temperatures were in the 5* to 7* C range, we detected local anomalies of high biological activity at 40* to 50* N.
Thus we have obtained data on the spatial distribution of the main biochemical and gas components in the Atlantic, including the Northern and Baltic Seas. ATP and BALM concentrations varied between 91 and 54,200 ng I-1, and 22 and 13,500 ug C I-1, respectively; and the level of hydrolytic enzyme activity changed from analytical zero to very high values. Fluid gas flows showed high concentrations of methane and ethane; but the aggregate concentration of helium and hydrogen was quite insignificant. Consequently, the values of the main geochemical indicators and of the gas components in the Pacific Ocean were two- or threefold as high as those in the Atlantic. This means enhanced and high levels of bioactivity.
Our geo- and biochemical findings over large water areas in the Atlantic and the Pacific have furnished important information on their geoecological status. Overall, it corresponds to the norm and involves global natural processes within the ocean. Acting in concert, these continuous processes account for a stable ecology there. And what concerns the anomalous zones where bio-produce is the highest (the Peruvian upwelling area, for instance), these are affected by short-term cyclic processes, two or three weeks in duration (we established this fact way back in 1973). In these periods eutrophications (plankton bloom) of the water is up, which is a token of enhanced and high biological activity. Technogenic loads may cause the eutrophication phenomenon to persist and even end in water toxication.
The data collected during our two transoceanic voyages in the Atlantic and the Pacific have confirmed the relevancy of our idea: international ecological refuges should be set up in the central parts of both oceans so as to preserve the gene pool of the planet's microorganisms. This idea is attracting the attention of oceanologists in other countries too.
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