some effects of acidified water on the early development of roach (rutilus rutilus l.) and perch...

WATER RESOURCES BULLETIN VOL. 12, NO. 1 AMERICAN WATER RESOURCES ASSOCIATION FEBRUARY 1976

SOME EFFECTS OF ACIDIFIED WATER ON THE EARLY DEVELOPMENT OF ROACH (Rutilus rutilus L.)

AND PERCH (Perca fluviatilis L.)'

Niklas Johansson and Goran Milbrink'

ABSTRACT: Fertilized eggs of perch (Perca fluviatilus L.) and roach (Rutilus rutilus L.) were reared at different pH values both in the field and in the laboratory. The results from the laboratory tests revealed that both species showed at least a 50% decrease in their hatching frequencies when reared at pH values below 5.6. At pH values below 4.6 both species studied show an almost complete lack of reproduction. The field studies with eggs from different lakes indicated that there might be an adaptation, manifesting itself as a higher frequency of hatching in water with a composition similar to that of the natural habitat. Field experiments also showed that the roach is more sensitive than perch to low pH values. (KEY TERMS: perch; roach; pH values; roe; hatching.)

INTRODUCTION

During the last decades, the acidification of Scandinavian inland waters has become a great problem, on which much interest is now focused.

One of the most striking indications of increasing acidification is radical changes in the natural fauna, e.g., a gradual reduction in the number of fish species (Almer 1972), a rapid decline of recruitment into younger stages of certain species and sudden fish death.

There is now little doubt that the stages from spawning to some time after hatching are those most sensitive to acid environment (EIFAC 1969, Johansson et a1 1973, Johansson and Kihlstr8m 1975, Johansson and Runn 1975, Mount 1973).

MATERIAL AND METHODS

Laboratory part ROACH. Eggs of roach from Lake Mzlaren, Drottningholm, were artificially fertilized

in their natural water and were then allowed t o stick as a mono layer to one side of ordinary object glasses (some 300 eggs/glass). The glasses were then attached to

'Paper No. 75096 of the Water Resources Bulletin. Discussions are open until October 1, 1976. 'Respectively, Institute of Zoophysiology, University of Uppsala, Box 560, S-751 22 Uppsala,

Sweden; Institute of Zoology, University of Uppsala, Box 561, S-751 22 Uppsala, Sweden.

39

40 Johansson and Milbrink

polyethylene holders, which prevented the eggs from coming into contact with the bottom and the walls of the transport buckets and the hatching apparatus. In this condition the eggs were transferred to 5 buckets, each containing some two liters of water from Lake Mzlaren which had previously been adjusted to 5 different pH values with HC1 of analytical grade. These solutions were used only during the transport t o the laboratory in Uppsala. The pH value in each solution before and after the transport (transport time 1 h) is given in table 1. After the transport the object glasses with their holders were quickly transferred to the hatching apparatuses, identical to those described by Johansson and Runn (1975). The rearing water was made up by 2/3 tap water and 113 dist. water, adjusted to the desired pH with HCl of analytical grade and equilibrated for at least 3 days before the beginning of the experiment. The pH in each solution and number of adjustments during the experiment is given in table 2.

TABLE 1. pH Values Recorded in the Solutions Used During the Transfer of Roe of Roach, Before and After the Transport.

Solution No. 1 2 3 4 5

pH before

pH after

-

7.2 6.0

7.2 6.2

- ~ ~~~~

5.5 5.1 4.7

5. I 5.3 5.0

TABLE 2. Duration of the Experiments, Number of Adjustments, Variation, Arithmetical Mean and SD of pH in Each Solution During the Studies. The Last Column Gives the Variation

in pH During the First Two Days of Rearing (Roach).

Variation of pH

Extreme Experiment during Solution pH values Adjustments duration, Number of Arithmetical f i iSt number observed made to pH days adjustments mean of pH SD two days

R 1 7.5-8.0 7.5 15 12 1.1 0.234 7.5-7.9

0 2 6.0-6.3 6.0 15 11 6.1 0.108 6.0-6.3

A 3 5.4-5.8 5.5 15 10 5.6 0.112 5.4-5.5 C 4 5.0-5.4 5.1 16 10 5.2 0.093 5.0-5.1

H 5 4.14.8 4.7 15 6 4.7 0.043 4.7

P 1 1.8-8.0 _ _ _ JO _ _ _ 8.0 0.067

E 2 5.5-5.8 5.5 "10 9 5.6 0.112

R 3 5.0-5.4 5.0 10 8 5.1 0.126

C 4 4.54.8 4.5 10 8 4.6 0.100

H 5 4.0-4.2 4.0 I 4 4.0 0.065

Some Effects of Acidified Water 41

The number of object glasses that were transferred to each solution were: solution No. 1 : 6 glasses, No. 2-4: 2 glasses, and No. 5: 3 glasses.

On the second day of rearing one glass from solution No. 1 (PH 7.7) was transferred to each of the other solutions (pH 6.1, 5.6, 5.2 and 4.7) and one glass from solution No. 5 (pH 4.7) was transferred to solution No. 1.

The variation in pH during the first two days of rearing is given in table 2. Once a day all dead eggs were counted and removed from the glasses.

The temperature increased during the experiment from 16.0"C to 16.5"C. The eggs were kept in darkness during the night and in dim artificial light during the day. When the eggs began to hatch, all fry were counted once a day and removed from the apparatuses. The experiment was terminated when the last egg had hatched or died in each solution. The duration of the studies is given in table 2 .

PERCH. Due 'to the difficulties in obtaining artificially fertilized roe of perch, naturally fertilized (not older than 12 h) roe was used. The roe originated from a single female from the same place as the roaches mentioned above. The fertilized roe was divided into pieces (some 1500 eggs in each), and transported to the hatching apparatuses in the same way as the roe of roach. The pH values in the different transport solutions were, 7.8, 5.5, 5.0,4.5,4.0 and the drift of pH during the transport was less than 0.1 unit in all the solutions. The rearing solutions in the hatching apparatuses were prepared and adjusted as mentioned under roach above. The pH in each solution during the study is given in table 2. The temperature increased during the experiment from 16.5"C to 17.0"C and the light conditions were as for roach (above). The number of dead eggs was determined once a day and most of 'them were then removed from the hatching apparatuses. At the time of hatching, all fry were counted and removed on the day of hatching, so that the study was terminated when all eggs had hatched or died. The duration of the study is given in table 2. The pH was determined in both studies with Radiometer PMH 221.

Field part The experiments were performed in two lakes south of Stockholm in the Wval lake

system, called Lake StensjGn and Lake Trehh ingen (59'1'1" 18"19'E and 59"12'N 18" 18'E respectively). The pH values in these two lakes during the study are listed in table 3.

TABLE 3. Variation in pH During the Experiments in the Lakes Studied.

Extreme values Number of observed observations

L. Stensjon

L Trehorningen ROACH

L. Stensjon

L. Trehgrningen PERCH

5.76.0 6

5.0 2

5.6-5.8 4

4.7-5.0 4


The roe of the species studied was obtained in the same way as mentioned under laboratory part, but fertilized in water from Lake Stensjon and Lake Treharningen respectively. Different animals were always used for the field and the laboratory parts. The fertilized roe was then transported to the lakes in the same buckets as in the laboratory study (transport time to Lake Stens jh 1 hr and to Lake Trehcrningen 2 hrs). To protect the roe when reared in the lakes, a modified equipment of that described by Johansson and KihlstGm (1975) was used. The equipment consisted of an outer container, made of dark blue polypropylene, holding some 20 liters. Two walls were cut out of the container to enable a free passage of water through the container. On the top of the container there was a covering plate with six holes and in each hole a polyethylene tube was inserted (inner diameter and height 70 mm) with a bottom consisting of a net of nylon (aperture 1 mm). The containers were placed in the lakes so that the covering plate was on the same level as the water surface. The roe was placed in the tubes, the roe of perch free and the roe of roach on object glasses as described above. The number of eggs studied is given in table 6.

The number of hatched and dead eggs was determined at least twice a week, and these were removed from the tubes. At the same time the pH in the tubes was recorded (table 3) with the “Porto-matic pH meter 175” from Instrumentation Laboratory Inc. To estimate the degree of fertilization of the roe of roach and perch obtained at Drottningholm, samples of roe were reared in the laboratory at Drottningholm in running water from Lake Malaren. For this purpose an apparatus similar to that used in the field studies was used.

PERCENTAGE O F H A T C H I N G

’0°1

ROACH

50

Figure 1 a. Percentage of Hatching of Roe of Roach Reared in the Laboratory.


P E R C E N T A G E PERCH OF S U R V I V A L

S U R V I V A L TO H A T C H I N G

0 SURVlVAL TO THE EYED STAGE

Figure lb. Percentage of SuMval to the Eyed Stnge and to Hatching of Roe of Perch Reared in the Laboratory.

RESULTS

Laboratoly part The hatching frequency of the eggs reared without any transferring operations

between water of different pH values shows a clear trend of higher mortality at decreased pH values, as is illustrated in figure l a and l b , and listed in table 4 together with a statistical analysis. In figure l a the percentage of survival of perch embryos to the eyed stages is also given. Note that the different solutions are named after their arithmetical mean values of pH as given by table 2. The results reveal that both species are strongly influenced by increased hydrogen ion activity, and that perch here seems to be somewhat more sensitive than roach in that respect. The low hatching frequency of perch in the control solution might be due to a lower degree of fertilization since the degree of fertilization of the roe of perch was determined to be - 89% and that of roach almost 100%. The hatchmg frequency of the eggs transferred to another pH after 24 hours is listed in table 5. As a comparison, the results from the groups not being transferred (table 4) are also given in table 5 in the same way as the transferred groups. All groups reared in the control solution during the first 24 hours have been pooled (last line). The mortality thus obtained does not differ significantly from that recorded in any of the groups pooled.


TABLE 4. Hatching Frequency of the Roe Studied in the Laboratory and a Statistical Analysis Between the Values (Test of Heterogenity).

Note that the Different Solutions are Named after their Arithmetical Mean Values of pH (table 2).

Number of Percentage Roe from PH eggs studied of hatching X2 P

7.7 330 89.1

6.1 3 79 81.5

ROACH 5.6 636 39.5

5.2 5 I0 30.4

4.7 552 5.6

7.93 < 0.01

169.90 < 0.0005 10.95 < 0.001

115.33 < 0.0005

PERCH

8.0

5.6

5.1 4.6

4.0

1237

1245

1175

1802

1844

52.7

11.9

5.9

1.7

0

437.35

26.79

39.1 7

30.95

4 0.0005

< 0.0005

< 0.0005

< 0.0005

TABLE 5. Mortality in the Groups Reared in One Solution During the Study Compared with the Mortality in the Groups Reared in Two Different Solutions. The Group of Eggs Transferred from Solution No. 5 t o Solution No. 1 after 24 Hours is Called 5-1 and that Transferred from Solution No. 1 t o Solution No. 2 is Called 1-2, etc. pH Values are Given as Arithmetical Mean Values (table 2). The Rearing Period during the First 24 Hours is called Period A and that after is Called Period B. The Last Line Shows the Sum of All Eggs Reared in Solution No. 1 During the First 24 Hours.

EBs pH during pH during Dead during Dead during Total reared in period period Number periodA periodB mortality

solutionW A B ofems No. % No. % %

1

5-1

2

1-2

3

1-3 4

1-4

5

1-5

1

7.7

4.7

6.1

7.7

5.6 7.7

5.2

7.7

4.7

7.7

7.7

7.7 7.7

6.1

6.1

5.6 5.6

5.2

5.2

4.7

4. 1

3 30

4 22

379

328

636

348

510

450

552

412

1928

15

76 15

19

75

9

96

8

177

11

62

4.5 21 6.1

18.5 126 36.4 4.0 55 15.1

5.8 163 52.8

11.8 310 55.3

2.6 175 51.6 16.8 301 63.5

1.8 240 54.3

32.1 344 91.7

2.3 365 79.2 3.2 _ _ _ _ _ _

10.9

47.9

18.5 55.5

60.5 52.9

69.6

55.1

94.4

79.7


In all groups studied there were slight attacks of fungi for a few days in the middle of the rearing period. Fungi were never Seen to attack living eggs.

PE RC E NTAGE OF SURVIVAL

100

5c

TO THE EYED STAGE

1. Roe of roach from Lake Stensjzn. 2. Roe of roach from Lake MLlaren. 3. Roe of perch from Lake h&aren.

1 2 3 1 2 3

L A K E STENSJON L A K E TREHORNINGEN

Figure 2. Survival to the Eyed Stage (Roach) and to Hatching (Roach and Perch) of the Roe Used in the Field Study.


Field part

The roe of roach from Lake M3laren did, when reared in Lake Stensjan, hatch to some IS%, while the roe from Lake Stensjan reared in its natural water hatched to some 40%. There was, however, almost no difference in mortality between these two groups up to the eyed stage. No roe of roach reared in Lake Treh6rningen ever reached the eyed stage. The roe of perch was able to hatch in both the lakes studied, but the hatching frequency in Lake Treharningen was just half of that recorded in Lake StensjCjn (some 28 and 50% respectively). The percentage of survival t o the eyed stage (roach) and to hatching (both species) is given in figure 2 and table 6. In table 6 the total number of eggs in each group and the duration of each experiment is also listed.

TABLE 6 . Survival of the Different Kinds of Roe Used in the Field Studies, and the Duration of Each Experiment.

Days until Percent of aU eggs

embryos that hatched Number of reached the Percent and/or

Kind of roe Reared in eggs studied eyed stage hatched dead

ROACH from

L. M i h e n L. Stensjan 766 70.5 14.4 17

L. M h e n L. Trehbrningen 661 0 0 4

ROACH from

L. Stensji;n L. Stensjh 21 2 12.6 39.2 17 L. Stensjiin L. Trehbrningen 352 0 0 4

L. Mllaren L. StensjGn 85 2 --_ 49.9 1 1

L. M h e n L. Trehhingen I15 -_- 28.0 1 1

PERCH from

DISCUSSION According to figure 1 and table 4 it is obvious that both roach and perch are so much

affected by pH values below 5.6 that they show a 50% decline or more in their hatching frequencies. The reproduction of roach is affected even at pH 6.1.

Both species show an almost complete lack of reproduction at pH values below 4.6, which is well correlated with field observations in acidified lakes (Almer 1972). The field tests with roe of roach (table 6) gave a somewhat different result compared to that from the laboratory. The roe from Lake Milaren revealed a hatching frequency of 14% in Lake S tens jb (pH 5.9) while the laboratory tests gave a frequency of some 80% at pH 6.1 and some 40% at pH 5.6. The degree of fertilization was the same in both cases, although the roe was taken from different individuals. The temperature was about the same in the two studies. On the other hand the composition of the rearing waters was very different, which is shown by their specific conductivity values, Lake S t e n s j k -50, Lake Milaren: -250, and the water used in the laboratory: -400. (All values expressed as lo6 ohm" cm-' a t 25'C.) This indicates that not only the pH but also the total composition of the


water is of importance. This indication is strengthened by the observation that roe from Lake StensjGn, reared in its natural water, had a much higher hatching frequency than the roe from Lake Mslaren, reared in Lake Stensjh. The hatching frequency of the roe from Lake StensjGn reared there (-40%) is close to that observed in the laboratory of roe from Lake M’rilaren reared at pH 5.6. These facts might indicate that the roe of roach from Lake Stens jh is better adapted to water with low specific conductance or that the sudden decrease in ionic strength of the medium when the roe from Lake M’glaren was transferred t o Lake S tens jh was detrimental in itself. It is, in this respect, interesting to note that there is no difference in the percentage of survival up to the eyed stage in the two cases (figure 2).

The test with roe of roach from both Lake Stensjh and Lake Maaren in Lake Trehorningen resulted in total death before the eyed stage was reached, which was expected as there are now no roach in that 1ake:Test fishing in the spring 1974 in Lake Trehzrningen gave only 5 perch (mean weight close to 600 g), and one small pike (Larsson, M. the County Administration of Stockholm, unpubl. material). Similar fishing in Lake Stens jh revealed a diversified fish fauna, which had not changed markedly since the 1920’s (Alm 1928).

The hatching frequency of roe of perch in the laboratory and in the field are strikingly different. The temperature during the experiments was about the same, which is illustrated by their almost equal hatching time.

The roe of perch is in contrast to that of roach, surrounded by a layer of jelly which must be of importance for the oxygen uptake. When, there were moderate attacks of fungi on the dead eggs, as was the case with the perch eggs reared in the laboratory, the fungi sometimes also came t o surround some living eggs, which might have been detrimental t o the eggs (Lindroth 1946). This could be the explanation for the low hatching frequency in the laboratory.

When comparing the hatching frequencies in the field of the two species studied, it is obvious that roach is more sensitive than perch to increased hydrogen ion activity, as only perch was able t o hatch in Lake Trehkningen.

ACKNOWLEDGMENTS

Thanks are due to Fishery Consultants Gosta Molin and Mats Larsson for providing the fish material. This work was supported by a grant from the Fishery Board of Sweden and a grant from the National Swedish Environment Protection Board to Jan Erik Kihlstr6m.

LITERATURE CITED

Alma, B., 1972. Fbummgens inverkan p l fiskbestsnd i &tkustsj&r. Inform. fran Shvattenslab.

Alm, G., 1928. Fiskeribiologiska undas’tkningar i ifvavattnen. Sportfiskeklubbens Lsbok,

EIFAC, 1969. Water quality criteria for European freshwater fish - extreme pH values and inland

Johansson, N., J. E. Kihlstram, and A. Wahlberg, 1973. Low pH values shown to affect developing fish

Johansson, N. and J. E. Kihlstrgm, 1975. Pikes shown to be affected by low pH values during first

Drottningholm, 12, pp. 1-47.

1927-1928, pp. 5-19.

fisheries Water Res. 3,’pp. 593-611.

eggs (Brachydanio rerio Ham.-Buch.) Ambio, 2, pp. 42-43.

weeks after hatching. Environ. Res. 9, pp. 12-1 7.


Johansson, N. and P. Rum, 1975. Some effects of acidification on the early development of pike @sox lucius L). In manuscript.

Lindroth, A,, 1946. Zur Biologie der Befruchtung und Entwicklung beim Hecht. Meddelanden fran statens unders6knings- och f6rGks-anstalt for s%vattensfisket. Drottningholm, Stockholm. No. 24, pp. 1-1 74.

Mount, D. I., 1973. Chronic effects of low pH on Fathead minnow survival, growth and reproduction. Water Res. 7, pp. 987-993.

some effects of acidified water on the early development of roach (rutilus rutilus l.) and perch...

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