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