Mortality studies, Whole animal oxygen consumption and whole animal excretion

Results:

The percentage mortality and mean survival time of praFvn exposed

to different pH media were determined. (Table-1). No mortality of prawn

was observed from pH 5.5 to 9.0 which was considered as sublethal media.

The sublethal limit was determined after exposing the prawn for 168 h r s in

all the pH media continuously. The lethal pH in acidic medium was found to

be 4.5 pH where 50% mortality was observed and 100% mortality was

witnessed a t pH 3.5.

50% mortality of prawn was noticed a t pH 4.5 after 72 hrs of

exposure and though the prawn was continued in the same medium, no

further mortality was observed beyond 72 hrs. 100% mortality was noted

within 0.75 h r s a t 3.5 pH. However, the 100% mortality was found i n

alkaline medium with i n 2 hrs of exposure and 20% mortality was noted a t

pH 10.0 after 96 h r s of exposure which were considered to be the lethal

limits i n alkaline medium. The survival time for 100% mortality i n acidic

pH was far less when compared to alkaline medium.

The oxygen consumption of the prawn was depleted i n both acidic

and alkaline media under short term exposure (Table-2; Fig. 12). The per

cent depletion of oxygen consumption was more in acidic media (-28.18) than

in alkaline rnedia (-7.26). The unit oxygen metabolism (Fig.13) was

decreased in acidic (-25.53) medium and in alkaline medium (-7.27) when

compared to control. The maximum decrease was observed in acidic

medium.

The ammonia excretion (Fig.14) was highly recluccd in acidic

meclium (-3-1.15) after 24 hrs of exposure. But in allwline 111edium the

ammonia excretion was significantly elevated (+10.94) tvheri compared with

control. The excretion of ammonia is more in alkaline meciium than in acidic

medium. The ammonialoxygen ratio (Fig.15) was rccordeci lower in acidic

medium (-8.28), but it was higher in alkaline medium (+19.67) over their

respective controls.

Table-1 showing the percentage mortality and mean survival

tiine of prawn, Peliaez~s inonodon at different pH levels in both acidic

and alkaline media. Values are the average of 10 prawns.

Mean survival time (lirs)

0.75

72

16s

168

168

16s

16s

96

2

O/, Mortality

100

50

0

0

0

0

0

20

100

S.No.

1

2

3 .

4

5

6

7

8

9

P 1-1

3.5

4.5

5.5

6,5

7.5

8.5

9

10

10.5

Table-2 showing the changes in Whole animal oxygen

consumption, Unit metabolism, Aimnonia excretion and AfO ratio

(AmmonialOxygen) in control and short term pH exposed prawns. Each

mean value represents an average of 6 individual observations. Mean, t

S.D.; + or - indicate the percentage increase and decrease over control. 'P'

denotes the level of statistical significance.

Alkaline (pH 9.0)

1.97 + 0.106 - 7.26

2

3.

S.No.

1

4.

I

Control

2.12 - t0.098

Component

Oxygen Consumption (rnl of 0 2 consumed1

hrlprawn)

Unit Metabolism (nil of Ozlgm wet wt/ hr)

Ammonia (p moles of ammonia1 ,

animal/litre)

P < 0.001 I

P < 0.01

Acidic (PH 695)

1.52 Jt0.092 -28.15

AinmonialOxygen (A10 ratio)

0.354 k0.025

2.87 k0.203

0.253 -+_ 0.031 - 25.53 P < 0.001

1.89 10.141 - 34.15

I? < 0,001

1.35 f0.127

1.24 k0.035 -8.28 P<O.OOl

- --

1.62 L0.041 +19.67 P<O.OOl

Pig.-4. Acidic exposatre prawn i n a rlaedix

--- -- -- -- - - - -- -.P---l_

IS;'a'g,6. Dorsal view of control prawn

- - I - -_-_.- -_ -.. ___-- .. --_- -------.--I-I-------------.- --

pi),~, 7. %boa-sill v i e \ .~ of acidic e x j ~ o ~ e r r e pratvn.

Pig,8. Dorsal view of ;nlic:kline, csposuubc plmawn

Discussion:

Thc pl-I of the water body play an important laole i n the growth and

development of aquatic animals. In the present study a11 attcimpt w a s maclc

to uncierstand the impact of altered pH on t h e metabolism of' prawn, Pelzaeus

monodon. Pr.eliminary studies cal-rictl on tho lethal cfl'cclts of' nltercd p1-I

l-angcs t o ol)scll*\rc tl-icl moi*t:ility a n d lllcan S U ~ V I I ~ R ~ time of' ~ ) i* :~ \vn , w h i c h

lloll)< io I lnd crut tllc lc t l -~ i l ancl su1~lcth;~l 1~1l l l t s of' pT-1. Tllc stucly w a s aillled

to understand the diffex-ential impact of acidic and allcalinc rlleciia on the

various ~netabolic profiles of prawn.

Different 111-1 ranges i.e., f'r.0111 3.5 to 10.5 in acidic and alkaline

mcclin weye selected to fouild the survival limit of the prawn. No nlortality

was obscr\recl in the pH range of 5.5 to 9.0, ancl they survivecl through out

the pol.ioc1 of ospcrimuntation (7 days). The alterations in tllc environmental

pI-I from neutrality to p1-I 5.0 towards aciclic side a11d pEI 9.0 in allcalinc sicle

seems to be compensated by the prawn and thereby this range of pI-I can be

considered as sub-lethal p1-I f o ~ the prawn. Thc 50% mortality of prawn was

obse~ved at pI-I 4.5 in acidic: mcdium ;~f'lcr. 72 h1.s of c s p o s u ~ ~ and 100%

mortali ty was noticccl a t pI-3 3.5 wi th in 0.75 hrs of esposurc.

Sin~ilarly 2C)(jo of mortality has been noticccl a t plF1 10.0 in nllraline

mcclium nf'tcr 96 hrs of' csprrsure ant1 1 mor ta l i ty \.ilns f'ouncl a t pH 10.5

w i t h ~ n 2 11)-s of' uspvslayu. Sc)ve~.r\l in\~u,-;tigatoi-s also reported the acidic anci

alkaline lethal pH limits f o ~ dii'i'crcnt aquatic aniinals (Lloyrl and Jol.tlan

1964; Beamisll, 197'2; Daye ant1 Gnrsiclc, 1975; h ~ l ~ v t l ~ y , 1981) nncI they are

in support with the present s tudy . Se\rcl-al morphologicnl changes were

observccl in the prawn after exposure to the altered pH mcdia sucli as ,

changc in thc colour of t h e animal, mucous formation on the l~ocly, 1.ecluced

movement and loss of balance (I'ig.3 l o 11). The reasons fbr the 100%

r n u r t n l ~ t j - 111ig1~t be clue to tllc deleterious cl'fccts of the cstl-cnle pI-I media

which were not in co-ordination or compatible with regulation of metabolic

processes and survival of prawn. Though several reports were fou~ld on the

lethal limits of altered pH on different aquatic animals, a little \voyli has

been carried out to determine the physiological changes associated with the

mortality of prawn on exposure to the altered pH media.

Although a number of investigators have worlcecl eorlicl. on higher

and lower lethal limits of p1-I in various fish species (Bhaskar 1982, Sobha

Rani 1953). A little work has becn carried to determine the nletabolic

changes associated with the mort;ality of prawn on esposurc to allcrcrl 111-1

media. Several reasons can be attributed for the mortality of prawn in the

altcrccl 111-1 111(!dia. Tho f'il-st and nol-n~al reason might be the induced

hyposir (soridition in the bocly of tllc prawn. Tllc hyposia niigllt be clue to tlic

alteration in the haemolyn~pll pH. Similar conditiorl was reported in fish by

the cbar.lie~ ~vo~.kers on csI1osw.e to altc:l.ud p1-1 111cclia (Packer mid DUIISOII,

1970; r J o l ~ : l nson et C I ~ . , 1973; Ilivcly nl., 19'77; Neville, 1979a,b), which

resultcd :I dccrensecl osygen ca l*~y ing capacity of' the blood clue to Bohr ef'f'ect

(Prosscl. ;111d Brocvn, 1962). On exposure to lethal acidic medium, clecreased

blood pE-1 can be cnvisaged clue to the entry of W+ into the haemolympll from

the external media OY otherwise failure of gaseous excl~ange across the gill

surface. The hypoxic condition in prawn on exposure to altered pH media

might also be due to the reduced diffusion of gases across the gill

membranes. Prevailing of hyposic condition in prawn was also evicle~iced in

the prescrit study with the change in colour of the animal on exposure to

lethal pH. Several investigators reported tha t the coagulation of mucous on

the gill was responsible for the decrease in gaseous exchanges across the gill

surface i n fish (Vazlla et al., 1969; Vaala and Mitchell, 1970; Anthony et nl.,

1971; Daye and Garside, 1976). Similarly mucous formation on the gill and

body of prawn was observed on exposure to lethal acidic pH. In consonance

to the present observation, increased gill mucification was also observcd in

fish, not only on exposure to altered pH media but also to other stress

conditions such as hcavy ~uetals (Ashley. 1970; Eislcr and Gnrdncr, 1973;

Eisler, 1974), and pesticides (Kabeer Ahmad, 1979). Plonlia anci Neff (1969)

reported the secreted nlucous ~uldei. stress condition interferes wit11

cschn~igu of' gases a t the opitlir11:11 cal,illnry junction. .4nother reason for tho

prawn mortality in sub lethal pi-1 range cotllcl bc due to the damage of gill by

deraiigiilg the gill cpithclium leading to exposure of pilaster cells ancl

capillarics to the external pII media. ']'his type of injury to gill epithelium

was also reported by several investigators unclcr different experimental

conditio~is such as lethal pH (Carter, 1964), heavy metals (Gardner ancl

Yevich, 1970; Slridmore, 1970), oils (Gardner et al., 1975) and phosphorous

(Odense et al., 1972) and detergents (Schmid and IVIann, 1961). Daye and

Garside (1976) suggested the form of this injury to gill was identical to both

acidic and alkaline conditions, but for acidic condition the degree of injury

was some what greater than alkali. The observed mortality of prawn in

estreme alkaline pH could be due to the excessive mucification on the gill

alld the body leacling to hypoxic condition, ionic imbalance ancl gill damage.

I n additioil to the abovc ~~casons thc imbalance in the ionic

composition of the body could also be coi~sidercd another important reason

for the mortality of prawn in sub lethal pH. Neville (1979a,b) reported that,

in extreme acidic pH the loss of bicarbonate ions leads to acidosis and

mortality in fish. Several investigators also reportecl loss of sodium, calcium

and chlorlclcs f'rorn body surface of fish under lethal pH environment (Packer

and Dunson 1970,1972; Bearnish et nl., 1975; Lcivestad et al., 1976~1;

Leivestad ancl Muniz, 1976b; Lockhart and Lutz, 1976). So ionic loss might

induced mortality in prawn under acidic stress. However, the loss of body

ions has been considered to be a secondary factor over hypoxia for the

mortality of fish in lethal pH media (Packer. ancl Dunson 1970 and 1972,

Leivcstud and hluniz 1976n). Finally it can t 7 ~ attributed that the hypoxia,

gill damage anci bocly ionic irnbnlanco might bc ~csponsihle foi- the obscrvcd

The decreased survival time of prawn in estrenle lethal limits of

acidity and alkalinity might be due to increasecl intensity of stress a t

extreme pH ranges. It indicates the survival time of prawn ciepends on the

intensity of lethality exerted by hydrogen and hyclrosyl ions of the media

respcctivcly. Similarly decreased mean survival time WEIS reported in fish a t

extreme acidic pH (Packer and Dunson, 1972; Daye and Garside, 1975).

Differential response was observed in tlie mean survival time of prawn on

exposure to lethal acidic and allcaline pI-I. The mean survival time of prawn

in acidic medium (PI-1 3.5) with cent per c c r~ t morality which was lesser than

that of alkaline pH (10.5). This explains that the acidic medium exerting

6 5

rlc:c:reasc.cl osygcn consumption in fish on acute esposure to altered p1-1 illedia

(Murtlly, 1981; Bhas l ia~ , 1982; Sobha Rani, 1983). ./lr~othcr reason f'or the

decreased oxygen consumption of prawn might be due to a prevailcncc of

hypoxic condition. Reduced oxygen levels in acidic lnediurn was ~ e p o ~ t e d

earlier by several investigators (Bhaslrar, 1982; Sobha Rani, 1983) which

supports the prevailing of hyposic condition in altered pH meciia. The unit

metabolism of prawn was significantl>~ clccreascd in both acidic and nllialinc

rliedia suggesting recluceci rnctabollc acbtivi ty of' p r a w n to altcred pH media.

Tile drlcei*c~:~se i t1 unit mcltnbollsm o r ivc!lgl~t specific 0x3-gen consumption in

both ac-iclli: and all.;aline nleciia supports the existence of hyposic conditions

in the medium anci reduceci tissue osidations in animal. Anthony et nl.,

(197 1) 1.epol.tcd carller SL~C'II a possibility of' decl-eased cellular osida tion in

:~ltel.cld p I l meclia. The dec~case 111 unit rnetabolis~ll also envisages a

pvssil3ili~>, 01' ciecreased tissue 1.espiration a t subcellular level in prawn on

clspusul.ci l o altci'ecl pH mudla. Bascd on these observations one can precllct

thnt tho i.ectllc~ed tissue oxidations leading to clec~eased energy release which

might bc responsible for the mo~tal i ty of prawn in e x t ~ e m e pI3 ranges. The

a l tera t ions in whole animal oxygen consumption and unit metclbolisill of'

p n w n in altc.r.cd pll media wo~ilcl r.c!s\llt, signilic:ant co~npcns;\to~.y m c t ; ~ l ~ ) l i c

change. Hence, there miglit be signilicant impact on the ammonia excretion

of prawn on exposure to altered pI-I illcclia. So the ammonia excretion was

annlyscc3 in c:ont~.ol and orperimcntal p1.awns.

'I'he a~nmonia excretion was ~ c c a ~ d c d significant drop in prawn on

exposure to aeiciic medium, where as the same was significantly increased in

alkaline medium. This suggests tha t tissue metabolism involving the

nitrogenous compounds particularly proteins leads to the compensatory

changes. The decreased ammonia excretion might be due to reduced

ammonia production in the body through the inhibited amino acid oxiclation.

Where as the elevated arnmorlia escrot ion in alkaline rneclium suggests the

increased catabolisn~ of proteins in turn the amino acicls. The NO ratio

which forms a inarker towards the alnmonia cscretion by the prawn pel- unit

osygen consumption which was lower in acidic ~nedium and higher in

allralinc mediurn. The lowered A10 ratio in acidic medium suggests the

possibility of decreased ammonia formation througl~ tlie amino acid oxidative

reactions of prawn. Several investigators reported the accumulation of free

amino acids, the elcvatii~g tissue proteolysis ancl decreased amino acid

clsidatio~>s unclci- dil't'ercnt stress cunditions (Poortmans and Delisse, 1977;

B h a s k ~ ~ ~ ~ ~ \ f-Ial'anath et al., 1978; Koln~ et al . , 1975; Bhaskar et al., 1962).

Ilowcvul. l l l u l l igll h l O rnlio in n l l t a l ~ ~ l c nlccliunl suggests t h e possibility of'

increased ammonia production through amino acid oxidations.

. \n , \ thc l s 1.c:isvn f u r tllc roc1uct:ci ammonia excretion could be due to

amn~onln i~ulc;~secl during the osiciative reactions might have been utilized

towards the maintenance of haemolynlph pH to counteract the acidic stress.

Since the blood pH of tissues was decreased in the acidic mediuin (Janssen

and Randall, 1975; Neville, 1979a,b; Bllaslinr, 1982). So the involvenlent of

ammonia in the haelnolymph buffering reactions might also be another

reason for the decreased ainnlonia excretion in prawn on exposure to acidic

waters. In addition, the decrease in ammonia excretion could be due to its

diversion into the formation of other conlpounds such as urea and glutamine.

The conversion of ammonotelic animals into ureotelic was reported earlier

under various stress conditions (Sasikala, 1981; Bhaslrar, 1982). Since

glutamine participates in the neutralization activities (Murthy, 1981;

Bhaskar, 1952; Harper et al., 1983), the ammonia might be retained in the

body for its synthesis. So the mobilization of tissue ammonia towards the

formation of glutamine can be expected. Hence i t is obvious to understand

the changes in the contents of nitrogenous end products at the tissue level in

order to provicle a proper assessment of the observed decrease in an l~~lonia

excretion of prawn on exposure t o acidic medium. In view of the arntnonia

production in tissues associated with the break down of nitrogenous

compounds, proteins and amino acids, their analysis was ulicler talccn in the

next chapter.

r 1 I hc rh;ingcs in ~ v l ~ o l c animal oxygen consumption, unit metabolism

: ~ i i ~ l i i 111 1111 i l l i ; l ~ ~ x c l ~ e t ~C) I I of' pr;1\~11 011 exposure to altered pH media suggests

t11:tt t h u ~nctabolism of prawn might also be altered under imposcd pH

stress. Since the whole aninla1 osy gcn consu~~lp t ion and uni t metabolisn~

happens to be the markers for the i n t e ~ n a l tissue metabolism, the

alterations in these para1neteu.s undel. PI-I stress can impose modulations in

the metabolism a t subcellular level. I-Iencc the present stucly was extended

to the tissue organic constituents in o ~ d e r to find out the changcs in tissue

reserves.

I II

Fig.12. Oxygen Consumption

I Acidic

i Fig.. 1.1. Ammonia 'i

. U *

2 - h

L- ?.

1.5 - h Cr

> 1 , ,* \

o - r -

O Control

m Acidic

> Fig. 13. Unit Metabolism

0.4

0.35 k 5 0.3 3 U 0.25 3 = 0.2

3, Q 0.15

k - 0.1 w .+- -

0.05

0 /

Fig. 15. Amlnon i;dOsygen

0 Control

rr Acidic

Oxygen Consumption

Fig.lG. Percentage Change

Ammonia

Unit Metabolisrn l-7

Tissue Proximate Analysis

Results:

The changes in the tissue somatic index, dry weight, water content,

total carbohydrates, total proteins, total lipids of liepatopancreas were

analysecl in both. acidic and alkaline media (Table-3; Fig.17 to 24). The

tissue sornatic index, dry weight, total carbohydrates, total lipids were

decreased considerably in both acidic and alkaline media when compared to

control. The water content was increased in both acidic ancl alkaline media

than control. But the total protein content was decreased in acidic medium,

with an increase in alkaline medium.

The tissue somatic index (-36.56), dry weight (-7.57), total

carbohydrates (-21.65) and total lipids (-12.98) of hepatopancreas were

depleted in acidic medium over control. But the water content was slightly

elevatcci in acidic mcclium (t1.33) than control. I--Iowever-, the total protein

conte~lt was deplcted in acidic mediunl (-5.07) when compared to control.

The tissue somatic index (-40.65), dry weight (-6.65), total

carbohydrates (-16.20) and total lipids (-4 1.83) were depleted in alltaline

n~ecliurn than control. But the water content was sligktly increased with non

signif'ica~il change (4-1.17) when compared to control. But the total protein

content was elevated (+14.60) in alltaline medium over control.

'l'i~(: 1.uciuction of tissuc somatic index and total lipids of' prawn

hepatopancl.cas was rllorc in allialinc meclium than in acidic mecliun~ over

control. Thc depletion of dry weight, total carbohyclrntcs was n~asirnum in

acidic mcdiunl than in all.ralinc mcciiu~ll when compar*ed to control. The total

proteirz content was significantly ciec~i~easccl in acidic meclium, but i t was

elevated i n alkaline medium over control.

T21e changes in whole animal wcight, tissuc somatic index, d ~ y

weight,, water content, total carbohydratcs, total proteins aild total lipicl.

levels of muscle were analysed in both acidic and alkaline meciia (Table-4;

Fig.25 to 33). The whole animal weight was increased in both acidic ancl

alkaline media over control. But, the total carbohydrates and total lipid

levels were decreased in acidic and alkaline media when compared to

control. Tissue somatic index and total proteins were depleted in aciclic

rnediuni with a n elevation i n alkaline r-iledium than control. The dry weight

of prawn l~iuscle was depleted with an elevated water content in both acidic

anti alkaline media over contl.01.

The whole animal weight of prawn was slightly reduced (-2.00) i n

acidic medium than control. The tissue somatic indes (-1.69), dry weight

(-1 1.87), total carbohydratcs (-4 1.02), total proteins (-29.62) and total lipids

(-29.66) of muscle were depleted in aciclic rncclium over control. However the

whole animal weight (+$.33) was sigrlificantly increased on exposure to

alkaline ~netliurn than control.

r i Iissuc sonlatic, inclcs (+$I.lSi, ~ v ~ t c r content (t3.67) and total

protein (-t7.2(.)) contcnts of' musc.le \vc.l.r1 ulcvatcd in alkaline mcdiul-tl when

compa~~cd ~rvilh control. 111 contrast, thc dry weight (-17.59), total

carbohycl~*;~tes (-2 1.27) ancl total lipids (-1 7.94) were significantly dccrcased

in 111usclc of' prawn 011 exposure to allcalinc nncdium

i n gcncral, the tissue somatic, index ancl total proteins of prawn

~nusc lc L\~L 'YU C \ C P L C ~ C C I in acidic ~ n e d i u m , but clcvatecl in allraline meclium. In

actclitioil thc ctry weight was clepleted more in alkaline medium than in acidic

medium when coml~ar.ecl to control. Thc total carbohydrate and total lipid

contcnts were depleted more in acidic rnediunl than in allcaline nlediui11 over

control.

'l':i1>1~,1-:3, showing thc cilifferent colnponcnts in control and short tern1

],I-I cbsliohrlti p~-rrrc l l~ 11 C ~ C L t o p c r ~ ~ cr-errs. Each mefin value is an average of

i i 1 1 i l i 1 1 o t i o I210:1n, i S.11.; t- or - indicate the p e ~ c e n t n g c

I : I o r I 0 1 . 'P' denotes the level of statistical

signific~xncc. 'NS' is non-sign~fi'icant.

S.No.

1.

2.

3.

4

5 .

6

Component

Tissue Somatic Ixidex (%I

Dry Weight (rnglgm wet weight)

Water Content (mglgm wet weight)

Total Carbohydrates (mg/gm wet weight)

Total Pro t e in s (mg/gm wet weight)

Total Lipids (mg/gm wet weight)

Control

4.33 1- 0.230

150.00 + 12.44

850.00 4 52.17

23.64 rtr 1.17

87.09 k 8.11

28.85 + 2.53

Aciclic (pH 6.5)

2.75 + 0.174 - 36.56 P<O.001

138.64 + 9.68 -7.57 P < 0.01

861.36 + 63.09 + 1.33 NS

18.52 t- 1.44 -21.65 P < 0.001

80.06 2 5.34 - 8.07 P < 0.001

25.13 f 2.01 -12.93

P < 0.001

Alkaline (PH 9.0)

2.57 k0.205 -40.65 P<O.OOl

140.02 + 11.13 -6.65 P < 0.01

854.93 + 71.84 '+ 1.17 NS

19.51 rt 1.06 - 16.20 P < 0.001

99.81 + 9.73 4-14.60 P < 0.001

16.80 3- 0.972 -41.83

P < 0.001

Table-.I skewing thc different components in control and short tern1

pH exposed prarulz. nzr~scle. Each mean value is an averngc of 6 individual

observations. Mean, 4 S.D.; + or - indicate the percentage increase and

decrease over control and 'I?' denotes the level of statistical significance and

'NS' non-significant.

Component Control

1,

Acidic (pH G.5) 6.25

-t 0.503 + 4.67 NS

Alkal ine (PH 9.0)

6.5 -t 0.378 + 8.33 P < 0.001

Whole animal weight (gm>

Tissue Somatic Index (%>

Dry Weight (mg1g.m wet weight)

6.00 rt 0.421

4.

45.67 -t 2.51

172.73 -t 13.14

5

6.

Water Conten t (~ l~glgm wet weight)

44.90 It 3.08 - 1.69 NS

152.22 4 12.07 - 11.87 P < 0.001

527.27 + 68.82

'l'otal Carbo11ydr.ates (nl glgnl tve t weight)

Total Pro te ins (mglgm wet weight)

49.85 -+_ 4.16 + 9.15 P < 0.001

142.35 + 11.60 - 17.59 P < 0.001

Total Lipids (mglgm wet weight)

20.46 F 1.76

115.98 - -t- 10.13

34.12 + 2.08

12.07 + 1.05 - 41.02 P < 0.001

81.63 k 6.07 -29.62 P < 0.001

16.11 -t- 1.18 -21.27 P < 0.001 124.33 + 9.12 +7.20

P < 0.001

24.00 .) 1.91 -29.66 P < 0.001

28.00 t- 2.40 -17.94 P < 0.001

Discussion:

The hcpatopancrcas sccnls t u bc Inore effected than thc n~uscle of

prawn on exposure to altered pI3 meclin. The tissue soniatic inclex (TSI) was

lowered on exposure to acidic medium. The TSI represents the proportionate

relationship of growth between the whole animal anci the rcspcctive organ

(hepatopancreas). In the present study the TSI was noticcnbly lower on

exposure to acidic medium over control. The decreasecl trend of TSI suggest

that the acidic stress reduced the size of hepatopancreas. So, it can be

attributed that the size of hepatopancreas might be reduced i~respective of

the body size leading to the reduced TSI. The decrease in TSI suggests that

the acidic stress might reduced the size of hepatopancreas in proportion to

the \vl1olc body. The dec~eased wl~olc animal weight and the lowered TSI

was reported by several investigators under various stress conctitions

(Narasimha Murthy, 1981; Murthy, 1951; Bhaskar, 1952; Blair et nl, 1996).

In the present stuciy also, the whole animal weight was decreasecl on

cxposure to acidic medium whicli supports that the acidic stress showing

prominent inlpact on the l~epatopancreas of prawn which inturn leads to

dccrcasc in the whole body weight o f the animal. So, the grotvth and

function of hepatopancreas might be regulated by the pH, the optimum pW

may hc i.c,lt~:l.cfiii 1\11. I 11c nr~i.m;il i i~i~(*t ion of the oiagan. Thc dry matter of the

hepato11ani~i~c:?s \ i fas significantly redu~ecl suggesting the operation of lytic

activities onclin~. acitumulntion of' water. Thc ~ v n t e r content showed no

sig~lil ' i~fl~l t c*l~;~ngci o i v ~ ) l * thr norm:11 tissue suggest the lytic activities were

~cspansibli: for the tlcc~cased dry mattel- rather t l ~ n the accu~llulation of

water. Thc anot11ci. reason for the dec~cascd dry matter in the

hcpatopanc~eas of p lmvn on csposure to acidic nledium might be due to the

mobilizat,io~i r ~ f ' tho tissue constituents towards hacrnolyniph or tissue

metabol is i~~. 111 support of the present data, decreased dry matter was

observed in liver of different animals under various stress conditions

(Bhasliar, 1952; Almon and Dubois, 1985). The decreased dry mattcr in t11c

hepatopancreas of prawn might suggest diversiol~ of tissue reserves towards

the energy release under imposed aciclic stress. A slight accunlulation of

water was observed i n hepatopancreas, however the elevation was not

significant, which envisages the possible derangement of osmotic and ionic

balance i n hepatopancreatic tissue. Since the blood pH of the fish exposed to

acidic waters was changed towards acidic side (Vaala and Mitchell, 1970;

Dively et al., 1977), the in take of Hf through the gill might responsible for

the decreased blood pH. Since the blood pI-I decreases in aciclic medium,

higher H+ levels can be expected in the blood. Due to the presence of these

prutons in the I ~ l u i ~ c l , usmotic fu~lctions might be impaired leading to altered

pcrmuubility plrlpcrties (Harper et al., 1993). I n view of such a condition in

t l ~ e blood i t is likcly that the liepatopancreatic tissue might have undergone

the dernngccl osmurcfiulnti~~g function resulting an accumulation of water,

p~obably wit11 nil increasccl efflux of sodium find chloridc ions (Paclce~ and

D~u~lson, 1972; 1,civcstad and Muniz, 197Ga). Cha i~gcs in thc ell-y ~llattet. ancl

the water coiltent resornbles the alterations in osmotic and ionic regulations

in cell (Bia and Def'ronjo, 1981; Murthy, 1981; Bliaskar, 1982; Cipres et al.,

1995). Since hydrogen and hydroxyl ions are directly involved in the

regulation of ionic balance both in inedia and the animal, studyiilg of the dry

matter and the watcr content changes in the l-repatopancrcatic tissue of'

pmwn an exposure to alterccl pl-I media might helps to find out the changes

in the ions and their iiivolve~~lent in various metabolisms.

The total carbohydrate levels have been considerably depleted in

;he hepatopancreas of prawn. Since the pH of the medium forins a stress on

wawn and under stress conditio~is the glucose of the blood was reported to

,e elevated (Adibi et al., 1975; Paul and Adibi, 1976), i t is likely that the

lepatopancreas reserves might have been mobilized towards the blood

omponemts. Since the carbohydrate forin a n immediate source of energy

nd . the hepatopancreas is concerned with ionic and osmotic regulations

(Potts ct ~ 1 . . 1967) which are energy dependellt processes, depleted

carbohyrlratc lcvuls in the tissue might suggest the mobilization of

c a r b o h y d r ; ~ t ~ @ s to\vnrds r-ncrpy rcleiise when prawns were exposed to acidic

mcdium. Si ~nilarl~y, t hc total prutcin content was also significantly depleted

suggesting the onset of nt:tlve pvotcolysis in the tissue or reduced synihclic

processes. Since the acidic conditioils activate the protease activity (Bhaskar

Haranath ct crl., 1978)) it is likely that the tissue protein might have

degraded and mobillzed as branched chain amino acid in to the blood stream

as seen in various animals subjected to different stress conditions (Paul and

Adibi, 1976; Paul et nl., 1978). The total lipid content was also depleted in

the hepatopanc~eas on exposure to acidic medium suggesting the onset of

lipolysis in the tissue, which envisages the active nlobilizatio~l of tissue

reserves towards the energy release. Such a mobilization of organic

constituent might responsible for the significant decrease in the dry matter.

(Christensen and I-langen, 1939; Baldwin et al., 1973; Rennie and Jol~nson,

1974; Paul, 1975; Rennie et nl., 1976; Holloszy et al., 1977). Since lipid for.ms

the chief fuel during severe and sustained activities (George anci Jyothi,

1958) and acidic environment cxerts a potent stress condition on the aquatic

animals, the noticed decrease in the hepatopancreas in the lipid levels on

exposure to acidic stress indicates the stepping upon the lipid metabolism

involving the mobilization and utilisation of lipid components to meet the

additional energy demands.

On exposure to alkaline medium the hepatopancreas of prawn

shnwect reduceci TSI. Since the TSI represents the relationship between the

growth of the animal in general and proportionate growth of the organ in

particular, thc lowe~ed TSI might indicate the reduced weight of the

hepatopancreas oil exposure to allialine medium. Though the whole an i~na l

weight of' the prawn was i~~crensecl when cxposed to alkaline mediunl

however the '1'SI of hepatopancreas was reduced which indicates the growth

of the hepatopa~~creas was not proportionate to the growth of the whole

body. This was also evidenced when we observe the dry weight of

hepatopancreas which was decreased on exposure to alkaline medium. The

decreased dry 111atter might be due to the diversion of tissue reserves

towards the energy release or the operation of lytic activities and/or

accuinulation of water. The water content showed non-significant change in

the hepatic tissue on exposure to alkaline rnedium suggesting the least

impact on osmotic properties of the hepatopancreas. Similar reports have

been observed in the hepatic tissue of fish on acute exposure to altered pH

media (Murthy, 1981; Bhaskar, 1982). The total carbohydrates and the total

lipids were depleted suggesting the stepped up lytic processes or decreased

synthetic activities. The i~laxinlurn depletion being the total lipid content

than the total carbohydrates in the hepatopancreas of prawn. Since the dry

matter was decreased which might more prone to tissue degradation, and

Sudclcn and acute exposure to the sublethal acidic and allcaline

waters of' p~xrsrn resulted drastic changes in the tissue organic constituents,

exhibiting thc impact of altercd pH nlcdia on the mobilization of various

tissue reserves into different metabolisms. The hepatopancreatic tissue

showed consistent depletion in TSI on esposure to both the acidic and

alkaline media. The TSI depletion was more in allraline ~nediurn than in

acidic medium. Since the TSI indicate the relationship between the growth

of both organ and the whole animal, the reduced TSI suggest the lowered

weiglit of the hepatopancreas on exposure to altered pH inedia in proportion

to tlie whole body weight. This rnigllt be due to the mobilization of the

organic constituents towards the energy release. Though the whole animal

wcigllt was increasecl on cxposure to allialirle pI-I, the TSl was recluccd which

suggest the lowered weight of the hepatopancreas. This was supported by

the reduced weight of the dry matter observed in both acidic and alkaline

media. The decreased dry matter envisages the active mobilizaton of tissue

constituents towards blood and lor tissue metabolism.

Since the oxygen consumption of the prawn was depleted over the

normal level (Table-2), mobilization of hepatic constituents into the

haemolylnph to a large extent can be envisaged. The hepatopailcreatic

tissue seems to have the least impact on osnlotic properties and ionic

regulation as there nras no accumulation of water on the tissue on acute

exposure to acidic and alkaline media. The total carbohydrates and total

lipid of hepatic tissue showed masin~uni depletion with lesser protein

depletion in acidic mcdium. In addition on exposwe to alkaline i~lecliuln the

total carbollydratcs and total lipids were also decreasecl. EIowever the total

protein content was clevated iil the liepatopancreas of pranrn on exposwe to

allralii~e meciium. Since the carbohydrate forms an immediate source of

energy and the hepatopancreas is concerned with the main site for the

detosificatory mechanism (Harper et al., 1983) which is energy dependent

processes, depleted carbohydrate content in the tissue might suggest the

mobilization of carbohydrate towards the energy release when the prawns

were exposed to altereci pE-I stress. The protein depletion was minimum

when compared with other components suggesting the possibility of little

proteolysis in the tissue in response to acute exposure to acidic medium. The

depletion of total lipids envisages, since hepatopancreas forms a reserve

source of lipid material in gencral (Harper el aL., 1983; Lehninger, 1993) and

as pH forms stress condition, the mobilization of lipids towards haemolymph

constituents to meet the energy demands can be envisaged. Interestingly

the protein content was elevated in allraline medium can be esplail~ed on the

basis of geared up synthetic activities with reduced proteolysis which was

water was changed towards acidity was noticed (Vaala and Mitchell, 1970;

Divcly et c ~ l . , 1977; Bllasliar, 1982). Similarly intake of 1-1' ion thl*ough the

branchial filaments can be envisaged leading to dec~ease in the pH of the

blood with a higher proton content can be espected. In the presence of high

protons, osmotic and ionic regulations will be inlpaireci going to altered

permeability properties (Love et al, 1968; Bhaskar, 1982; Harper et al.,

1983). In view of such a condition in the blood it is likely that the rnuscle

tissue might have had deranged osmo and ionic regulation resulting in the

mobilization of organic constituents. Since the prawn was u n d e ~ pH stress

condition, the muscular carbohydrate and lipid contents might have been

mobilized for the same and the present results were in consonance with the

earlier reports in fish (Reitman et al., 1973, Murthy et al., 1951, Sobha Rani,

1983; Bhaslrar and Govindappa, 1986a). Similarly, the total protein content

was also significantly depleted suggesting the onset of active proteolysis of

the tissue. The muscle shows high proteolysis in general (Siarnak et al.,

1976; Pozefsky et al, 1976; Bhaskara Haranath, 1979, Harper et al., 1983;

Lehninger, 1993) and earlier studies reported that acidic conditions activate

the protease enzyme activity (Bl-~askara Haranath, 1979; Bhashr , 1982). It

is likely that the tissue proteins might have clcgradccl d n~obilized as

branched chain amino acid into the bloocl stream as seen in the a~lirnals

subject to other stress conditions (Adibi et al., 1975; Paul and Adibi, 1976;

Paul et aL., 1978; Sobfia Rani, 1983; Sobha Rani e! al., 1986).

The whole animal weight of prawn was increased on exposure to

alkaline medium suggesting the active anabolic activity rather than reducecl

catabolic processes. The alkaline pH was nlore suitable for the g~owth and

development of the prawn (Raju. 1993). The elevated body weight of prawn

in allialine nlediui~i in the present study is in consonance with the general

practice of aquaculture. hi support of the elevated body weight of prawn,

tissue somatic index of muscle was also increased on exposure t o alkaline

medium, which envisages the proportionate growth of n~uscle along with the

body weight. In the muscle the dry matter was significantly reduced

suggesting the elevated catabolic activities or accumulation of water.

However, the water content was shown no11 significant change which

indicate that the muscle seems to have least impact on osmotic and ionic

activities as there was no accumulation of water on acute exposure. This

tissue also showed maximum depletion of total carbohydrates and lipids with

a lesser increase in total protein content. The carbohydrates and lipids

happens to be chief organic reserve constituents in muscle tissue which are

labile to metabolic break down under ally stress condition (Bhaskara

Haranath, 1979; Reddanna and Govindappa, 1980; Murthy et al., 1981;

Madhul.1. 1 i-)!j:)), i c ; ~ d i n g to t h ~ i y cf'flus ~ n t o \?loot1 sti7rlanl (:an be expected.

S~IICC t 1 1 ~ pla:ln'n Lvns ut~cler stress i~ol~clition, thc ~nusculal- lipidwmight have

been mvl~i1lzt:ri towa~,tls tile ilne1.g)' rc1tx- t~~ (I~isol,c:~.g, 19'71). Thi? total protein

rc~n ten t \LVi ls signil'ict;l~ltl!' c ~ l t ~ v ; ~ t t ~ i i s i ~ g g u s t i ~ l g L ~ C J o~isot of'synthotic- ;ic,ti\.itius

in the tissuc. 111 view of the wl~ole anl~nal wcight n7as incrcascd on exposure

to allialine medium, the elevatcd protein content in i~~usc lc might support

incr.casec1 whole body weight of pmwn.

The whole animal weight of prawn showed non-significant change

o n exposure to acidic meclium. 1-Iowwc~, the s:lme was significantly elevated

in all;;-xlinc mediuin which indicates the n1l;ulinc medium is providi~~g

positive en\ril.onnzent for the grotsrth anti developule~lt of' prawn. The TSl of'

muscle was reciuced with no statistical significance in acidic nwdiuni and

elevated significantly on espusuye to alkalii~e meclium. As the TSI

r epcsen t s the rctlationship bctwcen gro\vth ancl clcvelopment of whole

animal and internal organs, the elevated TSI of nl~iscle indicates the growth

of' the tissue in proportion to the growth of whole animal. Thc clry weight of'

the muscle tissue was depleted in both acidic and alkaline mcdia, which

cnvisagcs th(3 activc i~lobilization of' tissuc constituciits totvtl~~cls t,ho l~loor i

and/or tissue metabolisms, which inturn leads to accumulation of ~vatcr in

the tissue. However, the water content showed no significant change on

exposure to altered pH media. I t was reported that the accu~nulation of

water prone to possible derangement and osmotic and ionic plexus (Murth?,,

1981). The non significant change of water content in muscle envisages no

effect on osmotic and ionic properties of muscle. The total carbohy drate and

total lipid contents have been considerably depleted in this tissue and the

maximum depletion was in the carbohydrate content. The percentage of

decrease was more on exposure to acidic n~eclium than in alkaline medium.

Since the carbohydrates and the lipids form an immediate source of energy,

the depletcd carbohydrate and lipid content in the tissue might suggest the

mobilization of carbohydrates and lipids towards energy release when the

prawn was exposed to altered pH media. The total protein content of muscle

showed differential pattern on exposure to altered pH media. On exposure

to acidic medium the total protein content was depleted significantly

suggesting the possibility of tissue proteolysis in response to acute exposure.

However, when compared to alkaline medium the total protein content was

significantly elevated in the muscle of prawn. The elevated protein content

in muscle suggesting the decreased tissue proteolysis andlor elevated

synthetic activities. The results were in consonance with the earlier rcports

a lne which showed the elevated proteins in fish nluscle on exposure to alk 1'

media (Sobha Rani et al., 1983). Therefore on acute exposure the prawn

muscle showed higher rate of protein degradation in acidic medium, while

the same was elevated on exposure to alkaline medium.

Fig.21. Percentage Change 1 Tissue Somatic

Hepatopancreas

Total Carbohydrates

#'

Fig.17. Tissue Somatic Index

4.5

4

3.5

3

2.5

8 2

'1.5

1

0.5

0

r \ r > Fig.19. Water content Fig.20. Total Carbohydrates

900

800

2 700 6 .I? 600 +3

U p, 500 2 E 400

300

zoo

100

0

Hepatopancreas fi'ig.22. Total Frot,eins Fig.23. 'l'ot a1 I,ipicls

E4 Acidic

'r. ' f \

20 1 Fig.24. Percentage Changc

kta Acrdic

CJ Alkaline

Muscle Fig.26. Tissue Somatic Index

\

r /

> Fig.28. IVater Content

Fig.29. Percentage Change 'i

a Acidic

Alkaline

Muscle f \

Fig. 30. Total Carbohydrates

I Acidic

J

I' \

Fig.31. Total Proteins 140

120 C3 3

.3 loo w HAcidic 2 80 2

20

0

\ J

~ i ~ . ' 3 2 . Total Lipids 1

C1 Control

I Acidic

Fig.33. Percentage Change

Total Proteins