environmental parameters affecting fish physiology in ...€¦ · possibly affect cataractogenesis,...
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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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