assessment of the physiological effect of altered salinity on greenlip (haliotis laevigata) and...
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SHORT COMMUNICATION
Assessment of the physiological effect of altered
salinity on greenlip (Haliotis laevigata) and blacklip
(Haliotis rubra) abalone using respirometry
Steve EdwardsSchool of Human Life Science, Launceston,Tasmania, Australia
Correspondence: Dr S Edwards, School of Human Life Science, Locked Bag1-320, Launceston,Tasmania 7250, Australia. E-mail:
Abstract
The early physiological response (3 days) of greenlip(Haliotis laevigata Leach) and blacklip (H. rubra Leach)abalone to a single abrupt change in salinity wasmonitored using a multi-channel open-circuit respi-rometer. The range of salinity tolerance for both spe-cies in this trial was 25^40 ppt. Indications fromother trials were that a margin of 2 ppt outside thisrange will cause mortality. Serum volume wasincreased by reduced salinity as much as 25% in theshort term, with equilibration of the concomitantwhole body weight increase (9.270.5%) occurringwithin 1h. The serum volume appeared to be de-creased at high salinity. There was little underlyingchange in basal oxygen usage levels, but signi¢cantbehavioural changes that a¡ected overall oxygenconsumption. Both high and low salinity appearedto reduce activity. Animals in low salinity exhibitpartial recovery of activity levels after1day in a man-ner similar to other stress responses. Animals at highsalinity (40 ppt) did not show recovery of activity le-vels over 3 days. Overall, these results suggest thatgreenlip and blacklip abalone will have little troubletolerating moderately low-salinity environments.
Keywords: abalone, blacklip, greenlip, salinity,respirometry, activity
Introduction
Salinity tolerance of abalone (Haliotis spp.) has be-come an issue of prominence in a commercial
context for recirculating systems and for less thanideal culture sites. Abalone do not inhabit extremelylow-salinity environments in the wild, but sometolerance is expected from distribution studies (Shep-herd1973) and from local knowledge. Long-term tol-erance by H. tuberculata (Basuyaux & Mathieu1998)was found for 26^38 ppt, with a decrease in growthrate noted at 26 ppt. Fewother long-term studies havebeen conducted.Short-term 31P localized NMR studies focusing on
bioindicators for stress (Higashi, Fan & MacDonald1989) on H. cracherodii and H. rufescens showed thathigh salinity caused rapid and large alterations instress indicating metabolites (within 10min). Recov-ery occurred in a complex refractory pattern over thenext 6^8 h. Low salinity was less stressful. That lowand high salinity representmetabolic stresses for aba-lone is further evident from the expression of heat-shock proteins (Drew, Miller,Toop & Hanna 2000).Mostmolluscs exhibit responses to salinity stresses
that are a combinationof inorganic and organic ionicrestoration of balance. Decreasing salinity elevatesvarious ninhydrin-positive substances, mostly freeamino acids, in many molluscs (Shumway, Gabbott& Youngson1977). Changes in the behaviour of mol-luscs and other species may be related to the de-mands of coping with rapid salinity change. Penaeusjaponicus exhibits high-salinity tolerance at the costof high-energy expenditure levels (DallaVia1986).Our intention was to identify the tolerance range
of the species involved in our local culture industryusing respirometry.
Aquaculture Research, 2003, 34, 1361^1365
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Oxygen uptake
Juvenile greenlip abalone (H. laevigata Leach;39.7170.2mm, 8.1470.11g, n5960) were raisedand housed at Marine Shell¢sh Hatcheries (MSH) atBicheno, on the East Coast of Tasmania. Blacklips(H. rubra Leach; 41.9370.13mm, 11.3270.1g, n5960) were transferred from Tasmanian AbaloneFarms by road (1h). All animals were mechanicallyremoved and then housed in one room in heavilyshaded tanks at 17 1C (Gilroy & Edwards 1998) forthe duration of the trial (November 1998 to January1999). Animals were held for 3^4 weeks under theseconditions prior to any experimentation.Holding tanks were round (80-cm diameter) ¢bre-
glass tanks, with a sloping base and central outlet,tangential inlet and white gel coat ¢nish. Abalonewere fed on a commercial diet (‘FRDC’ ^ compositionnot publicly available) at 3-day intervals.For each salinity experiment, 10 animals were
transferred to each respirometer chamber (2�blacklip, 2� greenlip) with food. Acclimation wasmonitored at normal (34 ppt) salinity for 3 days. Re-spirometer chambers were then brie£y opened forcleaning and placement of fresh food, closed againunder normal salinity conditions, and then salinitywas rapidly altered to 25,30 (by the addition of freshwater) or 40 (by the addition of sea salt) ppt for thenext 3 days.The additionof commercial sea salt is lessthan ideal, since this is actually nearly pure NaCl, butthe resultant change in ion balance (15% at 40 ppt)should not invalidate this study. Animals at 30 pptcontributed to general observations, but respirometrydatawere lost due to an oxygen electrode failure.The continuous-£ow multi-channel respirometer
system is detailed elsewhere (Harris, Maguire, Ed-wards & Johns1999).Greenlip abalone (Fig. 1) showed an initial high
oxygen uptake reducing over 2^3 days. This is a
pattern normally seen as abalone acclimate. The ac-climatized oxygen uptake value of day 3 is the pri-mary point of comparison, and for this there is noapparent e¡ect of the subsequent alteration to lowsalinity (Fig. 1) or high salinity (Fig. 2) at the end ofday 3. Abalone in one high-salinity cage did not ap-pear to acclimate as quicklyand there mayhave beensome moderate e¡ects of increased stress underlyingthe results seen here.Highly variable results and high uptake levels are
normally indicative of animals under signi¢cantstress. The oxygen uptake patterns for blacklipabalone show high initial rates, high variability fromhour to hour and generally higher results. Blacklipabalone did not reacha settled value during the accli-mation period in the low- (Fig.3) or high-salinity trial(Fig. 4). Oxygen uptake levels and variability reducedremarkably on change to low salinity and high sali-nity. While there are clear changes for blacklip aba-lone between day 3 and subsequent days, we suspectthat these changes are not representative of normalphysiological responses, but rather behavioural ones.
01020304050607080
1 2 3 4 5 6
oxy
gen
up
take
(mg
/kg
/hr)
day of treatment
34ppt. 25ppt.
Figure 1 Daily averages for oxygen uptake by greenlipabalone (Haliotis laevigata Leach) before and after salinitydecrease. Data are mean7SE of hourly values for eachtank for each day.
020406080
100120140160
1 2 3 4 5 6
day of treatment
oxy
gen
up
take
(mg
/kg
/hr)
25ppt.
34ppt.
Figure 3 Daily averages for oxygen uptake for blacklipabalone (Haliotis rubra Leach) before and after salinity de-crease. Data are mean7SE of hourly values for each tankfor each day.
0
20
40
60
80
100
1 2 3 4 5 6
day of treatment
oxy
gen
up
take
(mg
/kg
/hr)
34ppt. 40ppt.
Figure 2 Daily averages for oxygen uptake of greenlipabalone (Haliotis laevigata Leach) before and after salinityincrease. Data are mean7SE of hourly values for eachtank for each day.
Salinity e¡ects on greenlip and blacklip abalone S Edwards Aquaculture Research, 2003, 34, 1361^1365
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Behaviour
The reduction in activity evident under high salinityis consistent with other observations at the time ofdata gathering. Animals (same cohort) subjected tothe same conditions alongside these animals wereused for serum sampling (a separate trial). These ani-mals displayed no e¡ect of low salinity in terms ofhandling behaviour, removal from substrate, footmobility and ease of serum sampling. Animals sub-jected to high salinity were less mobile, extremely dif-¢cult to remove from substrate, had shrunken feetand were extremely di⁄cult to obtain serum from.Animals subjected to low salinity in the respirome-
try trial displayed a lack of mobility in the ¢rst day,but behave normallyafter that (Fig.5).The lowvaluesof the respirometry trace correlated with empiricalobservations of reduced animal mobility, as expectedfrombasic considerations of energetics for this family(Innes & Houlihan1985) or indeed for any organism.High levels of activity, seen as peaks above basal va-lues in the tracing, reduce on change to low salinitybut increase againafter a day.The end of the dormantperiod is the normal time (19:00 hours) for the eve-ning activity cycle of moving and feeding. This 1 daydormancy is seen when mechanically removing theanimals from their tanks (Edwards, Burke, Hindrum& Johns 2000; Ragg,Taylor & Behrens 2000) and isconsistent with known stress responses in ¢shes gen-erally (Beitinger & McAuley 1990). The greenlip de-tailed tracings (Fig. 6) display less activity overalland the animals become dormant for a shorter timeduring the initial period of low salinity.At all times during the monitoring, there was little
subsequent alteration to the underlying basal main-tenance oxygen uptake levels (settled values seen inday 3) of these tracings.
For abalone in particular, salinity reduction causesa decreased heart rate (Nakanishi 1978), which isexpected to give lower tissue perfusion and loweroxygen uptake by tissues as well as concomitantreduced activity.High salinity also produced a marked reduction in
activity seen in hourly tracings for both species. Thiscontinued for the durationof the trial.Wouldmobilityhave been enough, or recovered enough, to ensurefeeding and survival in any longer-term high-salinityexposure? In our recirculating holding systems atLaunceston, we noted multiple mortality eventsoccurring only when salinity was allowed to get toB42 ppt (four refractometer observations in other-wise healthy stock of mixed juvenile greenlip andblacklip abalone).At the completion of the trial, all animals were re-
turned to normal housing systems and su¡ered noadditional mortality (noted over the next month) asa result of their inclusion in the trial.
0
50
100
150
200
250
300
1 2 3 4 5 6
day of treatment
oxy
gen
up
take
(mg
/kg
/hr)
40ppt.
34ppt.
Figure 4 Daily averages for oxygen uptake by blacklipabalone (Haliotis rubra Leach) before and after salinity in-crease. Data are mean7SE of hourly values for each tankfor each day.
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12:0
2
12:0
2
12:0
2
12:0
2
12:0
2
25 ppt
oxy
gen
up
take
(m
g/h
r/kg
)
dormant
0:02
0:02
0:02
0:02
12:0
2
0:02
12:0
2
0:02
0:02
Figure 5 Hourly values for oxygen uptake before andafter salinity decrease for blacklip abalone (Haliotis rubraLeach). Data are single points of hourly values for eachtank.
0
20
40
60
80
100
120
140
12:0
2
0:02
12:0
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0:02
12:0
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0:02
12:0
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0:02
12:0
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0:02
12:0
2
0:02
12:0
2
0:02
oxy
gen
up
take
(m
g/h
r/kg
)
dormant
25 ppt
Figure 6 Hourly values for oxygen uptake before andafter salinity decrease for greenlip abalone (Haliotis laevi-gata Leach). Data are single points of hourly values foreach tank.
Aquaculture Research, 2003, 34, 1361^1365 Salinity e¡ects on greenlip and blacklip abalone S Edwards
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Weight gain
Three or four animals of each species from the abovecohort were placed in pre-weighed plastic mesh(2-cm squares) pockets that were closed using a cabletie to ensure that no animals could escape. After1-day equilibration in clean seawater at normal sali-nity, the pockets containing animals were removed,drained on their ends on an absorbent foam pad toallow drainage for exactly 2min and then weighed(average coe⁄cient of variation for drain/weight foreight trial pockets50.43%). After return to the sea-water, salinity was rapidly altered to 25 ppt andweight was monitored at1and 2 h later.The abalone gained 9.270.5% of their initial
weight within 1h (mean and SE of ¢ve replicates ofgroups of four animals), with no further weight gainin the next hour. Corrected for shellweights ofB40%of the total and serum volumes B60% of the wetbody mass, the short-term increase in serumvolume,before secondary equilibration with expanded cellvolumes, is 25%.This could easilya¡ect the hydraulic(muscle support) function of the blood and possiblya¡ect a number of other processes related to mobilityand activity. Salinity elevation will have the reversee¡ect on volume, thus accounting for the di⁄cultyin extracting serum samples from abalone in thiscategory.In an earlier report for a similar cohort at this site
(Boarder, Maguire & Harris 2001), it was noted thatsurvival was variable at 23 ppt for greenlips.We hadfull survival at 25 ppt in this study, a di¡erence ofonly 2 ppt. This margin is identical to the upper levelmargin between 40 and 42 ppt mentioned abovefrom less rigorous observations. This suggests that,like temperature sensitivity (Gilroy & Edwards 1998;Hahn1989), the margin between survival and deathcan be very small for these animals. Nonetheless,their range of full survival is 25^40 ppt, and theirability to adapt is greater at reduced rather than ele-vated salinity. This is hardly a surprise given theirnormal habitat. The hyposalinity range is similar tothat for H. diversicolor supertexta (to 25 ppt, Chen,Zhong, Wu, Cai, Guo & Zheng 2000) and H.kamtschatkana (to 23 ppt, Olsen1983).
References
Basuyaux O. & Mathieu M. (1998) E¡ets de la salinite¤ sur lacomsommation alimentaire et su la croissance de l’oursinParacentrotus lividus et de l’ormeau Haliotis tuberculata en
e¤ levage en circuit semi-ferme¤ . Bulletin de la Societe Zoolo-gique de France123,141^150.
Beitinger T.L. & McAuley R.W. (1990) Whole animal physio-logical approaches for the assessment of stress in ¢shes.Journal of Great Lakes Research16,542^575.
Boarder S.J., Maguire G.B. & Harris J.O. (2001) E¡ect of sali-nity on survival and haemolymph parameters for green-lip abalone. In: Environmental Requirements of Abalone.Fisheries Research and Development Corporation ProjectReport 97/323 (ed. by C. Burke, S. Edwards, S. Hindrum &J. Harris). University of Tasmania, Launceston, Australia.
Chen C., ZhongY.,WuY., Cai H., Guo C. & Zheng L. (2000)The e¡ect of salinity on food intake, growth and survivalofHaliotis diversicolor supertexta. Journal of Fisheries China24, 41^45.
Dalla Via G.J. (1986) Salinity responses of the juvenile pe-naeid shrimp (prawn) Penaeus japonicus. 1. Oxygen con-sumption and estimations of productivity. Aquaculture55, 297^306.
Drew B., Miller D.,ToopT. & Hanna P. (2000) Identi¢cationofexpressed HSPs in blacklip abalone (Haliotis rubra) duringheat and salinity stress. Journal of Shell¢sh Research 19,509.
Edwards S., Burke C., Hindrum S. & Johns D. (2000) Recov-ery and growth e¡ects of anaesthetic and mechanical re-moval on greenlip (H. laevigata) and blacklip (H. rubra)abalone. Journal of Shell¢sh Research19,510.
Gilroy A. & Edwards S.J. (1998) Preferred temperature andcritical thermal maximum of the Blacklip abalone, Halio-tis rubra Leach and Greenlip abalone Haliotis laevigataLeach. Aquaculture Research 29, 481^486.
Hahn K.O. (1989) Biotic and abiotic factors a¡ecting theculture of abalone. In: Handbook of Culture of Abaloneand Other Marine Gastropods (ed. by K.O. Hahn). CRCPress, Boca Raton, FL, USA.
Harris J.O., Maguire G.B., Edwards S.J. & Johns D.R. (1999)Low dissolved oxygen reduces growth rate and oxygenconsumption rate of juvenile greenlip abalone, Haliotislaevigata Donovan. Aquaculture174, 265^278.
Higashi R.M., Fan T.W.M. & MacDonald J.M. (1989) Monitor-ing of metabolic responses of intact Haliotis (abalones)under salinity stress by 31P surface probe localized NMR.Journal of Experimental Zoology 249,350^356.
Innes A.J. & Houlihan D.F. (1985) Aerobic capacity and costof locomotion of a cool temperate gastropod: a compari-son with some Mediterranean species. Comparative Bio-chemistry and Physiology 80A, 487^493.
Nakanishi T. (1978) Studies on the e¡ect of the environmenton the heart rate of shell¢shes II. E¡ect of temperature,low salinity and hypoxia on the heart rate of an Abalone(Haliotis (Nordotis) discuss hannai). Bulletin of the HokkaidoRegion Fisheries Research Laboratories 43,59^68.
Olsen S. (1983) Abalone and scallop culture in Puget Sound.Journal of Shell¢sh Research 3,113.
Ragg N.L.C., Taylor H.H. & Behrens J. (2000) Stress andweight loss associated with handling in the blackfoot
Salinity e¡ects on greenlip and blacklip abalone S Edwards Aquaculture Research, 2003, 34, 1361^1365
1364 r 2003 Blackwell Publishing Ltd, Aquaculture Research, 34, 1361^1365
abalone, Haliotis iris. Journal of Shell¢sh Research 19,528^529.
Shepherd S.A. (1973) Studies on southern Australian aba-lone (genius Haliotis): I. Ecology of ¢ve sympatric sites.Australian Journal of Marine and Freshwater Research 24,217^257.
Shumway S.E., Gabbott P. & Youngson A. (1977) The e¡ectof £uctuating salinity on the concentrations of freeamino acids and ninhydrin-positive substances in theadductor muscles of eight species of bivalve molluscs.Journal of Experimental Marine Biology and Ecology 29,131^150.
Aquaculture Research, 2003, 34, 1361^1365 Salinity e¡ects on greenlip and blacklip abalone S Edwards
r 2003 Blackwell Publishing Ltd, Aquaculture Research, 34, 1361^1365 1365