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Modelling the' Tknsforrnations, Transport, and Fate of Organic and R&iculate Matter of€ Southern California.

Find Report

August 1990 - November 1992

George A. Jackson Department of Oceanography

'Jcexas A&M University College Station, Texas 77843

November 1992

PREPARED FOR THE U. S. DEPARTMENT OF ENERGY UNDER GRANT DE-~05-90ER60924

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DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liabili- ty or responsibility for the accuracy, completeness, or usefulness of any information, appa- ratus, product, or process disdosed, or represents that its use woukl not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessar- ily state or reflect those of the United States Government or any agency thereof.

DlsaAMER

Portions of this document may be illegible in electronic image products. Images are produced from the best available original dOCUment.

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This project was' part of the multi-invcstigator, multi-disciplinary West Coast program to study the arbon flux In marine basins (Caiiforda ]Basin Study- CaBS).

There have becn two major projects during the last yea. The first has been to model the fate of a phytoplankton bloom by induding oaly physical processes. The most im- portant such process is coagulation, the formation of large aggregates by the multiple wWion and sticking of smaller ones. Coagulation processes have been intensively stud- ied in descriptions of smog formation, generation of raindrops, md water treatment and purification. The rate of coagulation depends OR the rate of colli4on between particles and the probability that two particles wili stick to form one when they collide. Because the collision rate is proportional ta the quare of particle concentration and alga growth is proportional to just the particle (algal) concentration, the equations describing rate of algal cancentration when there are only growth, coagulation, ryld s i n h g rates are nonlinear. Numerical solutions of the d e m t equations as well as mathematid s'm- plifiations show that magalation can plscx! a maximum kncentration that algae can

achieve, that this ioncatration is vithin the range of concentrations which have been observed, and that this concentration is extremely sensitive to algal size. Because in- creased coagnlation leads to larger particles which sink faster, coagulation can enhaace the movement of particles to the oceaa fioor. Coagulation can occur in non-bloom con. ditions as well, but will share the role of particle removal with such biological processes a$ zooplankton grwing. In either situation, it is a mechanhm for particle removal which has not been adequately studied.

Our second major project has been the application of inverse techniques to study par- ticle dynamics in the planktonic systems. A major problem with studies of planktonic food webs is the practical impoasib%ty of measuring material flows among all the com- partments. Tb6 has been especially true in the Southern California Sight where CaBS researchers have found that the large crustaceans, such as copepods and euphausids, for- merly bclieved to bkthe domiitant grazers on phytoplankton actudy consume a smail hct ion of the primary production. Most of the algal production appears to be con- sumed by the s d e r grazers, such as protozoans and microzoa, for which we have little infomation. By using inverse models which incorporate information from laboratory rneammnents as well a8 the actual Seld measurements, we b v e been estimating values for the unmeasured flm which are consistent with those Geld measurements that do exist and with laboratory measurements.

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Using the model, we have been able to estimate protozoaa and microzoan grazing rates. These results suggest that animal excretion is the dominant source of organic mattcr that sustains baeteria rathcr than phytophkton leakage. The total of flows going into

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each orgaSrm is more than twice the primary production, indicating the importance of recycling in the systcm dynamics. The differences between carbon, whidi can cisen- t i h y leave the planktonic system by being respired, and nitrogen, which is asentially consewed, give the two substances much different residence times in the euphotic zone.

We have fdrther extended the inverst: technique to include a description of the benthic community. This situation is complicated by the importance of chemical flux- and transformations of elements in addition to carbon and oxygen a well as the difxiculty of studying organisms at great depth. Our mults help to delineate the activltia of different bacterid communities and their interactions with lktget organisms. Our resdts accentuate the differences between a benthic community in a region with low oxygen

concentrations in overlying waters, such as Santa Monica Basin, and one where there is substantial oxygen.

Inverse techniques should form a udd adjunct to Add measurements when describing ecosystems. h’the planktonic case, our resW w e s t that the interactions with detritus and with dissolved organic matter are important and need to be measured.

In the last 3 years, there have beea 4 papers published, 6 papers accepted for publication, and 1 submitted but not yet accepted. All resulted from work at least partidy supported by this grant,

PUBLICATIONS R.ESULTINQ FROM THIS PROJECT

PUBLISHED

Jackson, G. A. 1990. A model of the formation of marine algal %ow by pliyiticrtl cow-

lation processes. Deep-sea RB6. 57:1197-1211.

Eldridge, P. M,, and G. A. Jzlckson. 1992. Benthic food web flows in the Santa Monica Bash estimated using inverse meth&logy. I s G. T. &we and V. Pariente (4s-), Deep-sea food chains and the global a b o n cycle, pp 255-276. Kluwer Academic.

Jahnke, R. A., aad G, A. Jackson. 1992. The spatial distribution of sea floor oxygen

coasmption in the Atlantic aad Pwific Oceans. 1% G. T. h w e and V. Pwicntc (cds.), Deep-sea food chains and the global carboa cycle, 296-307. Kluwer Academic.

Jackson, G, A., axld S. E. hchmann. 1992. Ef€ect of coagulation on nutrient aad light limitation of an algal bloom. Limnol. Oceanogr. 57: 77-89

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. ACCEPTED/IN PRESS

Jackson, G. A., and P. M. Eldridge. Food web andysir of a planktonic system off Southern California Prog. Ocemogr.

Jackson, G. A. Flux feeding as a mechanism for zooplankton grazing and its impIications for vertical particulate Aw. Limnol. Oceanogr.

Jackson, G.A., and S. E. Lochmaan. Modcling cwagdation in -fie ccosystems. In: II. P. van Leeuwen a d J. BufTie [Eds.], Environmental Particles, v. 2, Lewis Publishers, Boca &ton, Florida.

Jackson, G. A. Coagulation of marine algae. In: Euang, C. P., C. R O’Melia, and Y. J. Morgan (eds.) Aquatic chemistry: principles and applfmtion of interfacial and inter-species interactions in aquatic systems.

Jackson, G. A. The significance of the DOC pool for primary production estimates. To appeaz in “ICES Maxine Science Symposia”

Murray, A. G., and G. A. Jackson. Viral DyxteJmics: .4 Model of the Effects of Size, Shape, Motion and Abundance of SingbCelled Planktonic Organisms and Other Particles. Mw. Ecol. Pmg. ser.

SUBMITTED

Eldridge, P. M., axld G. A. Jackson. Benthic txop$ic dynamics in California coastal basin aad continental slope communities inferred using inverse analysis. Submitted to Marinc Ecology Progress Series, November 1992.

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