methionine metabolically induced thecataractogenesis, evidence of workwith other animals suggests that thesulfhydryl, rather than the methylgroup of methionine, is most importantin preventing methionine deficiencycataracts. One of the earliest detectablechanges in most cataract formations is arapid fall in concentration of sulfhydrylgroups. The sulfuydryl groups possiblyminimize conformational changes such

as unfolded proteins and the subsequentformation of disulfide cross-link bondsand insoluble proteins of high molecu­lar weights.

Soybeans and soy proteins often con­tain antinutritional factors such as tryp­sin inhibitors and hemagglutininswhich interfere with normal intestinalabsorption of nitrogen and metabolismof methionine. Such factors, as theypossibly affect cataractogenesis,

growth, and composition, warrantfurther stud y.

In summary, these studies show thatat least three nutrient-related lesionsoccur in the eyes of salmonid fishes. Adeficiency of an amino acid caused lenscataracts; a deficiency of riboflavin in­duced a lesion involving cornea andlens. A vitamin A deficiency causedlesions in the cornea and retina, but notin the lens.

MFR PAPER 1349

MFR Paper 1348. From Marine Fisheries Review, Vol. 40, No. 10, October1978. Copies 01 this paper, in limited numbers, are available Irom 0822, UserServices Branch, Environmental Science Information Center, NOAA. Rockville,MO 20852. Copies of Marine Fisheries Review are available from the Superin­tendent of Documents, U.S. Government Printing Office, Washington, DC20402 for $1. 10 each.

Thomas L. Meade is with the De­partment of Animal Science, Univer­sity of Rhode Island, Kingston, RI02881.

Environmental ParametersAffecting Fish Physiology inWater Reuse Systems

THOMAS L. MEADE

The incorporation of water reuse,based on microbiological treatment, inlarge-scale salmonid production sys­tems a few years ago was widely re­garded as a major breakthrough in pro­duction technology. Since that time,those of us who have been involved inthe development of water reusetechnology have seen the value of oureffort diminished by changing condi­tions and the appearance of physiologi­cal problems.

Innovative development work hasenabled us to offset some of the effectsof increased materials and energy costs,and meet the more stringent dischargecriteria. On the other hand, high mor­talities experienced in some facil itieshave been a severe setback, and clearly

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illustrate that when the environment isappreciably modified we can expect aphysiological response. U nfortunatel y,physiological adaptation is not alwaysadequate to insure survival.

Experience gained in culturing onespecies in water reuse systems is notalways transferable to another species,and, similarly, problems encounteredin one area are not necessarily experi­enced in another. Most problems en­countered are related to water quality.Such factors as pH, mineral content,metabolite levels, temperature, anddissolved gases may be critical. Ourmore recent research, which is mul­tidisciplinary in approach, has centeredon the relationship between environ­mental factors and the well being of the

cultured species as judged by biochem­ical, physiological, and pathologicaldeterminative procedures.

It is generally accepted that toxicityof ammonia is due to the undissociatedfraction, with its concentration beingtemperature, salinity, and pH depen­dent. Thus, environmental pH manipu­lation can be employed to increase tol­erance for ammonia. Since culturing inthe range pH 6.0-7.0 is not always de­sirable, we have endeavored to developa beller understanding of themechanism of ammonia toxicity. Datadeveloped to date suggests that im­paired respiration resulting from an al­tered acid base balance, with a corres­ponding blood pH shift, is the primarycause of mortality.

In water reuse systems employingmicrobial nitrification, nitrite, a micro­bial metabolite, may also be toxic to thefish being cultured. A wide range ofLCso's of nitrite for various species hasbeen reported. In our work, we havedemonstrated that nitrite toxicity is re­lated to temperature, oxygen concentra­tion, and chloride ion concentration. Inhigh salinity environments, nitrite has alow order of toxicity , and, in freshwater

Marine Fisheries Review

with a chloride ion concentration of lessthan I mg/liter, nitrite is extremely tox­ic. The oxidation of ferrohemoglobin toferrihemoglobin by nitrite or a deriva­tive of nitrite is observed in nitrite toxic­ity. Under normal conditions, there is achange in the color of the gill tissue andthe blood to a characteristic chocolatebrown color. In our work, we have alsoexperienced high mortality at moderatelevels of ferrihemoglobin with an ab­sence of blood color change. Thissuggests that a second mechanism maybe operative. At this time, we are look­ing into two possible mechanisms: one

involving interference in the final stepinvolving electron transfer in the res­piratory enzymes, and the other theeffect of stress on the production ofmineralocorticosteroids. In the case ofthe (atter, elevated blood bicarbonatelevels would result in alkalemia with itsassociated impairment of respiration.

Research is also underway on theproblems involved during smoltifica­tion of steel head trout in a water reusesystem. Although work in this area isstill in the exploratory stage, availabledata suggests that the problem is relatedto a lack of synchronization between

increased hormonal activity associatedwith smoltification and activation of theNa +K ATPase system in the gill tissue.

In conclusion, it appears that en­vironmental stress factors have a fargreater inRuence on normal growth anddevelopment than previously recog­nized. High density culture in waterreuse systems, although theoreticallypossible, is not without considerablerisk, and the risk will not be minimizeduntil we have a better understanding ofthe relationship between environmentalfactors and the physiology of the cul­tured species.

MFR Paper 1349. From Marine Fisheries Review, Vat. 40, No. 10, October1978. Copies of this paper, in limited numbers, are available from 0822, UserServices Branch, Environmental Science Information Center, NOAA, Rockville,MO 20852. Copies of Marine Fisheries Review are available from the Superin­tendent of Documents, U.S. Government Printing Office, Washington, DC20402 for $1.10 each.

MFR PAPER 1350

PCB-Induced Alterations inTeleost Liver: A Model forEnvironmental Disease in Fish

David E. Hinton is with the Depart­ment of Anatomy, West Virginia Uni­versity School of Medicine, Morgan­town, WV 26506. James E. Klaunigand Michael M. Upsky are with theComparative and EnvironmentalPathobiology Program, University ofMaryland School of Medicine, Col­lege Park, MD 20740.

DAVID E. HINTON, JAMES E. KLAUNIG,and MICHAEL M. LIPSKY

Man's population and continuedeconomic and industrial developmenthas led to increasing exposure of theaquatic environment to exogenouscompounds. Alteration in structure/function of tissues arising from expo­sure to these pollutants comprises ourworking definition of environmentaldiseases of fish. The response of fishtissues to environmental pollutants maytake either of two forms. In the first,

October /978

there is acute lethal injury. This may beexpected to occur after exposure to ex­tremely toxic substances. The secondform occurs following exposure tochronic sublethal concentrations of pol­lutants. This leads to an altered steadystate, compatible with life, wherechanges in structure at the tissue, cellu­lar, and organelle level can be co'tre­lated with alterations in function. Thosepollutants which lead to the latter form

of injury are noted by their persistencein the environment and their bioaccu­mulation.

The ability of fish to metabolizecompounds can, to a large extent,mediate the form of injury which re­sults. The primary locus of enzymeswhich metabol ize foreign substances isthe hepatic microsomal mixed-functionoxidative system (MFOS). This systemis capable of the detoxification of noxcious substances and the activation ofpotential carcinogens (Dallner, 1963).

The polychlorinated biphenyls(PCBs) are important industrial com­pounds which have been used in paints,immersion oils, electrical capaCitors,and heat exchange systems. Their pres­ence and persistence in the aquaticenvironment have been documented

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