A survey of the bottom fauna in Wood, Kalamalka and Skaha lakes in the Okanagan Valley I British Columbia

by

O. A. Saether M.P. MCLean

FISHERIES RESEARCH BOARD OF CANADA

TECHNICAL REPORT NO. 342

1972

, !I ,..

FISHERIES RESEARCH BOARD OF CANADA

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which is indicated on the title page.

*

FISHERIES RESEARCH BOARD OF CANADA

TECHNICAL REPORT NO. 342

A SURVEY OF THE BOTTOM FAUNA

IN WOOD, KALAMALKA AND SKAHA LAKES

* IN THE OKANAGAN VALLEY, BRITISH COLUMBIA

by

OLE A. SAETHER and MARGARET P. McLEAN

This work was carried out for the Study Committee, Canada-British Columbia Okanagan Basin Agreement.

This is the 27thFRB Technical Report from the

Fisheries Research Board of Canada

Freshwater Institute

Winnipeg, Manitoba

iii

Contents

Abstract ....................................................... 1

Introduction ................................................... 2

Methods and Stations ........................................... 3

Physical and Chemical Conditions... .............. ........ ...... 4

Notes on Invertebrates Found ................... ........... ..... 4

Oligochaeta ............................................. 5

Mys idacea ............................................... 7

Chironomidae ................................... . ........ 8

Gastropoda

Pelecypoda

13

13

Discussion and Surrunary ......... . ..................... . ......... 13

Wood Lake 14

Kalamalka Lake .......................................... 16

Skaha Lake .............................................. 17

Acknowledgments ................................................ 18

References ............................................ .. ....... 19

Tables ......................................................... 21

Figures ........................................................ 27

1

Abstract

The benthos of Wood, Kalamalka, and Skaha Lakes in the Okanagan

lake chain in the interior of British Columbia was examined.

Wood Lake has changed since Rawson's investigation in 1935

(Rawson 1939) from being a rich, eutrophic lake supporting up to as many

2 as 23,000 oligochaetes per m (at a depth of 23 m) to becoming practically

a biological desert. This is not caused by deteriorating 02-conditions,

but probably by some form of toxic compounds.

Rawson (1939) found that Kalamalka Lake was a typical oligotrophic

lake slightly richer than Okanagan Lake and that the chironomids made up

95 per cent of the benthic fauna. During the present survey the chironomids

made up only 55 per cent of the fauna. Thus a significant shift in the

fauna composition seems to have taken place, but to a smaller extent than

found by Saether (1970) for Okanagan Lake. The lake has still a typically

oligotrophic benthic fauna.

The benthic fauna of Skaha Lake is typical for formerly oligotrophic

lakes which, through pollution, are rapidly becoming eutrophic .

2

Introduction

The Okanagan lake chain ln the interior of British Columbia drains

an area of 2,400 square miles. Saether (1970) conducted a survey of the

bottom fauna of three of the lakes in the chain, namely Okanagan, Skaha

and Osoyoos. As the few single samples taken in Skaha Lake did not seem

sufficient to characterize that lake in detail, Skaha was re-examined

during the present survey. In addition two other lakes, Kalamalka and

Wood were surveyed.

Kalamalka Lake is the largest of three lakes lying in a valley

parallel to Okanagan Lake and draining into it through Vernon Creek. The

lake is about 154 km long, about 21 km wide, with a maximum depth of 142 m,

and a mean depth of 57 m. It covers an area of 26.5 km 2 and has a volume

3 of 1.5 km. The water renewal time is about 115 years.

Wood Lake drains into Kalamalka by a short canal and the two

together are sometimes referred to as Long Lake. Wood lake is about 7 km

long and 1.6 km wide, with a maximum depth of 34 m and a mean depth of

21 m. It covers an area of 9.4 km2 and has a volume of 0.2 km 3 . The

renewal time is about 109 years.

Since the survey took place a distillery located southeast of Wood

Lake has started operation. This distillery pumps water from Okanagan

Lake for cooling purposes, and discharges this water into Duck (Ellison)

Lake which drains v~ Vernon Creek into Wood Lake. The renewal time will

thus be changed to about 71 years in Kalamalka, and about 20 years in Wood

(Stockner & Koshinsky, MS 1971).

3

Rawson (1939) took a few bottom samples both in Kalamalka and

Wood in 1935. Except for characterizing Kalamalka as an oligotrophic

lake slightly richer than Okanagan Lake, and Wood Lake as an eutrophic

lake, his data are very sparse and no identification beyond groups were

~ade. The previous report from the survey of the bottom fauna in the

lakes of the Okanagan Valley (Saether 1970) contained a non-technical

summary giving a general introduction to the use of benthic indicator

communities for the trophic classification of lakes. Any interested

non-specialist is referred to this 1970 report for a better understanding

of the present paper.

Methods and Stations

Benthos samples were collected May 10-12, 1971. In Skaha Lake

the sampling sites were essentially the same as those taken during the

1969 survey (Saether 1970) with the addition of one sampling site in the

south basin. In Kalamalka and Wood the sample sites were chosen near

inlets and outlets with additional samples taken from the deep parts.

A new improved Ekman sampler (Burton and Flannagan, in press) was

used for the sampling. The samples were sieved through an 0.2 mm mesh size

whenever possible. Three samples were taken at each sampling site. All

three samples from Station 14 and 15, and second and third samples from

Station 1, 6, 8, 9, 11, 12 and 18, were sieved through an 0.6 mm mesh

sized sieve. In most cases the sediments filled up the samplers to about

2.5 inches from the top, i.e., the preferred level mentioned by Flannagan

4

(1970). Some of the littoral samples (1, 5 and 11) contained only a

couple of inches of sediment, mostly of sand and/or vegetation (Table 3).

Samples were preserved with 4 per cent formalin.

Physical and Chemical Conditions

(CCIW, Burlington, personal communication). The oxygen values in

Kalamalka Lake are close to saturation at all depths throughout the year.

The pH in the surface water varies between 7.8 and 8.5, and the bottom

waters between 7.6 and 8.45. The Secchi disc visibility varies from 5.0

to 18.0 m, while Rawson (op. cit.) found 6.7 m in August, 1935. The

conductivity values range from 370-425 ~mhos, but are mostly near 390 ~mhos.

In Wood Lake the oxygen distribution correspond to that expected

in an eutrophic lake. However, the deeper water is never completely

deoxygenated. The pH in the surface waters is 7.8-9.3, in the bottom

waters 5.7-7.9, and the conductivity values range from 302-394 ~mhos. The

Secchi disc visibility varies between 1.0 and 5.25 m. Rawson (~. cit.)

got readings of 2-2.5 m during an algal bloom.

Notes on the Invertebrates Found

The species or species groups found in the triplicate samples are

shown in Table 3, while some additional records of dead Gastropoda and

Mollusca are shown in Table 4. Only a few of the more important species

or species groups will be discussed here.

5

Oligochaeta

The same number of species were identified from this survey as

from the survey in 1969 (Saether 1970). However, 8 species from this

survey were not found in 1969 and 8 species from the 1969 survey were

not collected this time.

Naididae are found most commonly in the littoral zone associated

with vegetation. However, 3 specimens of Nais elinguis were found in

Kalamalka Lake at a depth of 18 m, and specimens of the same species were

found at depths of 38 and 52 m in Skaha Lake. This may indicate that Nais

elinguis also occupies the profundal zone. Similarly, 7 specimens of

Vejdovskyella comata were found at a depth of 3~ m ~n Skaha Lake (Table 3).

Among the Tubificidae collected, only Limnodrilus profundicola

(Verr.) is an indicator of oligotrophy (Brinkhurst 1965). It is usually

restricted to cold habitats. However, in contrast, the English localities

are a small pond, a polluted stream, and a canal (Brinkhurst 1965, p. 131)1

Only 3 specimens of this species were found, all in Skaha Lake, 2 in the

deepest part of the south basin, and 1 at a depth of only 1.5 m at Station

17 inside the breakwater in the south end (Table 3). During the previous

survey this species was present only in the two deepest samples (87 and

117 m) in Okanagan Lake.

The other tubificids found occur in all kinds of freshwater biotopes.

However, Tubifex tubifex (MUll) and particularly Limnodrilus hoffmeisteri

Clap. can, by mass occurrence, be taken as indicators of low oxygen level

and organic pollution. In such situations they are usually the only

6

oligochaetes present. 2 Stations with more than 1,000 individuals per m

of L. hoffmeisteri are represented in Fig. 1 by a solid circle . . These

stations are all in the deeper waters of Skaha Lake. Other stations with

more than 1,000 oligochaetes per m2 are presented in Fig. 1 by an open

square. All the remaining stations in Skaha Lake with the exception of

Station 14, at the inlet, belong in this category. In addition Station

8 in Kalamalka Lake, situated about 20 m from the incoming Coldstream

Creek, has more than 1,000 oligochaetes per m2 The identified specimens

of L. hoffmeisteri can be divided into two variants, the typical and the

flat-plate variant. The latter seems to be most common in Wood, Kalamalka,

and the south end of Skaha, while the typical variant is most common in the

main, north basin of Skaha.

Ilyodrilus perrierii Eis, is the only oligochaete found which has

been recorded only in areas west of the Rockies.

Rawson (op. cit.) surveyed Kalamalka and Wood Lake in 1936. At

that time all 8 samples taken in Wood Lake at depths from 15-30 m contained

more than 1,000 Oligochaetes per m2 and in one case as much as 23,000 per

2 m. During the present survey no oligochaetes were found at a depth of 31 m

2 and the maximum number per m was 548 at a depth of 6.3 m in the north end

of the lake. At a depth of 5 m about 350 m from the inlet the oligochaetes

were absent. The oxygen deficit in Wood Lake, particularly at such a

shallow depth as 5 m, is not large enough to explain the absence of

oligochaetes. In fact complete exhaustion of O2 very rarely seems to

take place (Stockner, Koshinsky, unpublished data). In addition 3 specimens

of Chironomus anthracinus type were present at these depths. The only

possible explanation seems to be a reaction to toxic compounds. Liebmann

7

(1960, p. 699) mentions that as a rule the arthropods are much more resistant

to toxic compounds (with the exception of insecticides) than soft-walled

invertebrates such as worms, molluscs and sponges. In the north end the

effects of the toxic substances entering the lak~ seem to be modified by

the close proximity to the canal connecting Kalamalka and Wood Lakes. At

certain periods the water from Kalamalka Lake enters Wood Lake.

Rawson (1939) found that chironomids made up 95 per cent of the

fauna in Kalamalka Lake while the remaining 5 per cent was made up of other

groups including oligochaetes. During this survey the bottom fauna was

found to be composed of 38 per cent oligochaetes and 55 per cent chironomids.

Thus a significant shift in the fauna composition seems to have taken place

similar to that found in Okanagan Lake by Saether (1970). However, the

shift is of a smaller magnitude and the scattered information given by

Rawson indicates that the total number of bottom invertebrates is at least

of the same order of magnitude as that found during the present survey. A

modifying circumstance may be that Rawson may have overfilled his samples

which primarily would result in too low numbers of oligochaetes (Flannagan

1970).

Mysidacea

One single specimen of Mysis relicta Lov. was found at Station 12

in Kalamalka Lake at a depth of 13.4 m. Mysis relicta was introduced to

the lake in September 1965 (Stringer 1967) and also released in 1966

(S.S. MacDonald, Regional Fisheries Biologist, Okanagan Region, Penticton,

8

B.C., personal communication). The above noted occurrence is the first

record of the species since the introduction.

Chironomidae

Among the Tanypodinae only Procladius (Procladius), Procladius

(Psilotanypus) and a single representative of the Thienemannimya group

were found (Table 3). In Skaha Lake Procladius (Procladius) is the most

common chironomid. It is, however, absent from the deepest station. This

is rather peculiar since this station also has the highest numbers of

tubificids (the main diet of Procladius), and does contain specimens of

much less tolerant species of chironomids (Table 3).

Potthastia cf. longimanus (Kieff.), Protanypus cf. morio (Zett.),

Prodiamesa cf. olivacea (Meig.) and Monodiamesa f.l. bathyphila (Kieff.),

the four Diamesinae found, were all present in Kalamalka Lake, while,

except for 2 specimens of Monodiamesa f.l. bathyphila, the other lakes did

not contain any Diamesinae (Table 3). Potthastia longimanus and Protanypus

morio are both characteristic in oligotrophic to mesotrophic lakes, but are

most common in moderately oligotrophic lakes. Prodiamesa olivacea is found

in nearly all kinds of freshwater environments (i.e., eurytopic and euryoecic).

There are at least three nearctic species of Monodiamesa, all undescribed.

The morphology of the adults of two of the species is intermediate between

~. bathyphila (Kieff.) and ~. ekmani Brund. Apparently also the ecology of

these two species is intermediate between M. bathyphila and M. ekmani.

The nearctic species seem to be characteristic in oligotrophic and mesotrophic

lakes, but they may, as M. bathyphila does, extend into the range of slightly

9

eutrophic lakes.

The Orthocladiinae are very common in Kalamalka Lake and were

represented in the bottom samples by 11 larval types (Table 3) . Skaha

and Wood Lake had only 2 larval Orthocladiinae types each. In Skaha Lake

2 specimens of Heterotrissocladius f.l. subpilosus were found at depths of

11 and 52 m respectively. At the time of the 1969 survey only ~. subpilosus

(Kieff.), the prime indicator of ultra-oligotrophic European lakes, was

known to have larvae of this type. Recent material from Lake Winnipeg

shows that there is another species of Heterotrissocladius with the same

larval type. This species is, according to adult collections, common over

most of central and western Canada and is apparently present in the lower

littoral zone as well as in the sublittoral and profundal zones of oligo­

trophic to mesotrophic lakes. Recently, examination of material from Florida

revealed a larva of the Heterotrissocladius subpilosus type! This is

probably yet another species.

The larva described by Saethcr (1970, p. 7) as genus near Trissocladius

is the most common chironomid in the samples from Kalamalka Lake. This

interesting larva, which also shows some similarities with Paraphaenocladius,

was, in Okanagan Lake, found at three stations between 26 and 33 m. In

Kalamalka it is present at all depths sampled (Table 3). Its absence from

the more eutrophic lakes indicates that the species is restricted to

oligotrophic to mesotrophic lakes.

The Cricotopus larvae of the "Paratrichocladius" type may be identical

with ~. alpicola (Zett.), a cold-stenothermous boreoalpine species which in

the Alps seems to be a profundal chironomid, i.e. contrary to other species

10

of Cricotopus. This species was one of the more common chironomids in

Kalamalka and was also present ln Okanagan Lake.

Two very interesting orthoclads were found in Kalamalka Lake. These

two species seem to be identical with those tentatively associated with

Parakiefferiella nigra Brund . and Parakiefferiella coronata (Edw.) by

Hamilton (MS, 1965) from the oligotrophic, mesohumic Marion Lake, B.C.

This association seems very doubtful, but if correct Parakiefferiella

clearly is a heterogeneous genus and these two species deserve two new

genera. Both species have a 4-segmented antenna with a relatively large

second segment and very small third and fourth segments. "Parakiefferiella

nigra" has a broad, hyaline, median part of ventromentum (Saether 1971)

with large ventromental plates anddorsomentum divided in two parts each

with 6 teeth (Fig. 3A). Anterior labrum seta (SI) is apically plumose, i.e.

different from all other Parakiefferiella except f. torulata Saeth. where

SI is split apically. "Parakiefferiella coronata" (Fig. 2B) is even more

peculiar with . the ventromentum and the dorsomentum nearly the same size and

without teeth, but with two small, median notches in the ventromentum. The

antenna has relatively large Lauterborn organs; the mandible has a long,

slender apical tooth and pointed, needle-like lateral teeth; the premandible

is somewhat reduced; the labrum and the epipharyngeal area is sclerotized

and void of chaetae, chaetulae or spinular, with the epipharyngeal area

consisting of a single plate with 2-3 weak setae on each side. The

postmentum is clearly divided. No S-setae were apparent in any of the two

specimens. They were either very small and weak or lost. Both those species

and particularly "P. coronata" gives further evidence for regarding the

11

"paralabial plates" as the ventral parts of the mentum as well as for the

correctness of the term mentum (Saether 1971).

The specimens of Thienemanniella found had the antenna slightly

less than half as long as the head, i.e. shorter than in any previously

described larvae of Thienemanniella.

The larvae of the Chironomus salinarius type, i.e. without blood­

gills, found in Kalamalka are probably identical with C. atritibia Mall.

This species seems to be relatively cold-stenothermic and characteristic

both in oligotrophic lakes and in the deeper layers of eutrophic lakes as

long as the oxygen deficiency is not too severe (Saether 1970, p. 7).

Larvae of the Chironomus semireductus type (small blood-gills on

10th segment and the blood-gills of 11th segment reduced to about 2/3 as

long as the segment is wide or less) were found in Kalamalka arid Skaha.

In Lake Winnipeg these larvae belong to the most common chironomids and

consist of two species both with hypopygia essentially identical to Chironomus

plumosus (L.) Larvae of the semireductus type occurs in oligotrophic as

well as in eutrophic lakes. They seem, however, to be most common in the

sublittoral zone of mesotropfiic to slightly eutrophic lakes.

The larvae of the Chironomus anthracinus type, common in all lakes

(Table 3), belong at least partially to C. attenuatus Walk. This species

seems to have much the same ecology as C. anthracinus Zett. (i.e. most common

in moderately eutrophic lakes) and, in North America replaces C. anthracinus

in most situations.

The specimens of Stictochironomus found in Kalamalka Lake apparently

is of the histrio type. S. histrio Pabr. is primarily a shallow water form,

12

while S. rosensch~ldi Zett. is characteristic of median oligotrophic and

mesotrophic lakes. Both types of larvae were present in Okanagan Lake.

S. rosensch~ldi has now been found from the northern basin of Lake Winnipeg

and is thus established as present on the nearctic continent.

A specimen apparently belonging to a genus near Polypedilum was

found in Skaha Lake. The ventromental plates seemed to be deformed without

any recognizable striation (Fig . 3D).

The Tanytarsini in general are most common in oligotrophic to

mesotrophic lakes. However, some species of Cladotanytarsus, one of which

may be identical with that found at Station 5 in Wood Lake and at slightly

polluted areas in Okanagan and Kalamalka Lakes, are often associated with

mild pollution and may be quite resistant to low oxygen levels. Species

with a similar ecology may also be found among Tanytarsus and seem to be

present in all 3 lakes (Table 3).

The antenna of one species (from shallow stations in Kalamalka and

Skaha Lakes (Table 3)) with a pedicel of the Lauterborn organ about three

times the length of the organ, i.e. as in Rheotanytarsus, but with the size

of the organ itself more like Cladotanytarsus is shown in Fig. 3C.

Saether (1970) and Hamilton & Saether (1971) mention several deformed

chironomid larvae from Okanagan and Skaha Lakes. No similar deformities

were found during this survey although 3 times as many samples were taken

in Skaha Lake. One possible explanation for this is that deformed larvae

are not able to survive for any length of time and since the present survey

was done in the second week of May very few larvae are the brood of the

year and hence deformed larvae were unlikely to be present.

13

Gastropoda

According to Hartman & Berg (1971) Lymnea columella Say., Gyraulus

deflectus (Say.), Promenetus exacuous (Say.), Amnicola lustrica Pils., and

Valvata sincera (Say.) are new to the area west of the Rockies. However,

Henderson (1925 p. 132, 139) mentions L. columella as probably introduced

in Oregon and Washington, and P. exacuous as present in several localities

in Washington and Oregon.

Pelecypoda

Although empty shells of Pisidium made up a considerable portion of

the sediments in Kalamalka Lake only 5 specimens were found, all at Station

8. These specimens were too juvenile to be identified. The dead Pisidium

(Table 4) consisted of 5 species, all except ~. walkeri common and generally

eurytopic. P. obtusale Pfeiff. and P. walkeri Sterki is not mentioned from

British Columbia by Herrington (1962).

Discussion and Summary

As mentioned by Saether (1970, p. 14) the main drawback with the

previous survey was the scarcity of samples and the lack of reared and adult

material to back up the identification of insect larvae. The present survey

has taken one of these points into consideration as the samples were in

triplicate. The second drawback has partially been improved by the rearing

14

of chironomid larvae from other localities. The triplicate samples in

Skaha Lake show that the samples previously obtained were probably good

samples, however,.the present samples also show that the previous

conclusions concerning the changes in this lake were probably not quite

correct. The finding elsewhere of Heterotrissocladius subpilosus type larvae

not restricted to oligotrophic lakes may indicate that the conclusions based

on the presence of this species in the 1969 survey were too rigid. On the

other hand Genus near Trissocladius and Cricotopus alpicola seem, based on

both surveys, to be useful indicator organisms and the Monodiamesa larvae

found seem to be at least as good indicators on oligotrophy as M. bathyphila.

Wood Lake

Rawson (1939) found that the lake had a benthic fauna characteristic

of a eutrophic lake with high densities of oligochaetes and chironomids. He

found that in all his 8 samples, there was more than 1,000 oligochaetes per

2 2 m and at a depth of 23 m there was as many as 23,000 per m. Today the

lake is practically a biological desert in most areas with no oligochaetes

and only 1 specimen of Chironomus attenuatus present, in triplicate samples,

at two of the stations. The two stations near the outlet, Station 4 and 5, are

obviously influenced by water entering the lake from Kalamalka and have a

fauna typical of a eutrophic lake. However, even at these stations the

number of oligochaetes per m2 is clearly lower than 1,000.

The limno1ogical data from Wood Lake does not give any information

which could explain the disappearance of a formerly rich fauna. The oxygen

seldom or never is completely exhausted at the bottom of the lake. Even if

15

very prolonged periods of O2 values close to zero occurred at the deepest

station, and thus give an explanation for this station, this explanation

would not be valid for the station at 5 m depth. It seems that the only

explanation possible must be the existance of some toxic compound. The

arthropods are much more resistant to toxic compounds than soft-walled

invertebrates such as worms, molluscs and sponges with the exception of

insecticides which strongly affects arthoropods, but have little influence

on worms and molluscs (Liebmann 1960, p. 699). This may explain that species

of Chironomus can live in the "desert" zones while oligochaetes are completely

absent and that the number of oligochaetes in particular has decreased

drastically. It also indicates that the influencing toxic compounds are

not insecticides. The sediments have been found to contain a very high

concentration of mercury (Stockner, personal communication). It seems,

however, doubtful that this concentration alone will be able to eliminate

the oligochaetes, as some other lakes with high mercury content still have

an abundance of oligochaetes.

There are no industries a~ound the lake and how and from where the

toxic compounds have entered the lake is an open question.

The establishment of a distillery southeast of the lake, adding

cooling water pumped from Okanagan Lake to the system and thus decreasing

the water renewal time from about 109 to about 20 years (Stockner and

Koshinsky, MS 1971) can only have beneficial effects on the benthos of Wood

Lake. However, the effects on Kalamalka Lake will in all likelihood be

detrimental.

16

Kalamalka Lake

Rawson (1939) found Kalamalka Lake to be a typical oligotrophic

lake slightly richer than Okanagan Lake. He also found, however, that

the Chironomids made up 95 per cent of the benthic fauna. The present

survey found that the Chironomids made up 55 per cent of the fauna. Thus

a significant shift in the fauna composition seems to have taken place,

but to a smaller extent than that found by Saether (1970) for Okanagan Lake.

The total numbers during Rawson's survey seem to be of at least the same

order of magnitude as those found during the present survey.

The combination of more than 1,000 oligochaetes per m2 and the

presence of Chironomus plumosus and anthracinus type (148 Chironomus spp.

per m2) at Station 8, situated about 20 m out from the incoming Coldstream

Creek, indicate that this stream, which goes through the outer limits of

the city of Vernon and drains an extensive cattle range area, may show some

mild pollution (Fig. 1, 2). Similarly Station 9, situated in the same bay,

has relatively many specimens of Cladotanytarsus as does Station 7, near

the canal from Wood Lake. However, these indications of mild pollution are

nowhere serious enough to affect the distribution of typical oligotrophic

to mesotrophic forms (Fig. 2, Table 3).

Kalamalka Lake is thus still a typical oligotrophic lake relatively

rich in calcium, and the changes which have taken place since Rawson's

investigations are of much smaller magnitude than those found in Okanagan

Lake.

17

Skaha Lake

Skaha Lake is an unusual lake in many respects. The morphometr~

is typical of an oligotrophic lake the oxygen values correspond to those

characteristic for moderately oligotrophic to mesotrophic lakes, the

nutrient load is typical for a very eutrophic lake, the primary production

seems relatively high, and the water renewal time is only 1.1-1.5 years.

Corresponding with these apparent contradictiens the bottom fauna

seemingly is also full of contradictions. There are more than 1,700

2 oligochaetes per m at all stations, and more than 1,000 Limnodrilus

hoffmeisteri per m2 at 4 of the 6 stations. At the same time Limnodrilus

profund icola is present in the south end of the lake. Chironomus spp. are

quite common at 3 of the stations and Chironomus plumosus type is present

at 2 of the stations. At the same time moderately oligotrophic to meso-

trophic forms are present at 2 of the stations [Fig. 2).

This kind of a benthic fauna is, however, not atypical for formerly

oligotrophic lakes which through pollution are rapidly becoming eutrophic.

The most unsuspected aspect is that the transition has not gone faster.

However, the high oxygen levels, the high ~ing rate as well as the close

proximity to Okanagan Lake with the possibility of recolonization from that

lake easily explains why the Oligotrophic forms still are present.

The absence of eutrophic forms at the deepest stations is perhaps more

puzzling. During the previous survey the only chironomid present at this

station was a Procladius (Psilotanypus). During the present survey, however,

6 species of chironomids were found, none of them in high numbers and none

of them typical for eutrophic biotopes. The presence of 2 specimens of the

18

Cricotopus silvestris type suggest that at least some of the species have

been washed out from the shore. The absence of more eutrophic forms may be

a result of possible currents near the bottom which may wash away some of

the detritus and thus create a situation where the food content is not high

enough for Chironomus spp. to compete with forms adapted to less nutrient

rich biotopes.

Acknowledgments

We are much indebted to Mr. J . F. Flannagan, H.N.C. BioI., Fisheries

Research Board of Canada, Freshwater Institute, Winnipeg, who participated

in the field collections, identified Ephemeroptera, Trichoptera and Mollusca

and criticized and corrected the preliminary manuscript.

Thanks are also due to Dr. D.G. Cook and Mrs. Muriel Smith, both of

the National Museum of Natural Sciences, Ottawa, for respectively identifying

the oligochaetes and the gastropods, to Mr. H. Ng, CCIW, Burlington, Ontario,

for supplying limnological data from Wood and Kalamalka Lakes, and to Dr.

John G. Stockner, Fisheries Research Board of Canada, Pacific Environment

Institute, West Vancouver, B.C., for comments on and corrections of the

preliminary manuscript.

19

References

Brinkhurst, R.O. 1965. Studies on the North American aquatic Oligochaeta .

II. Tubificidae. Proc. Acad. Nat. Sci. Philad. 117:117-172.

Burton, W. and J.F. Flannagan. In press. An improved Ekman-type grab.

Flannagan, J.F. 1970. Efficiencies of various grabs and corers in

sampling freshwater benthos. J. Fish. Res. Board Can. 27:1691-1700.

Hamilton, A.L., MS, 1965. An analysis of a freshwater benthic community

with special reference to the Chironomidae. II. Taxonomy of the

Chironomidae of Marion Lake, British Columbia. Ph.D. Thesis. Dept.

Zoology, University of British Columbia, Vancouver, B.C. 216 p.

Hamilton, A.L. and O.A. Saether. 1971. The occurrence of characteristic

deformities in the chironomid larvae of several Canadian lakes. Can.

Ent. 103:363-368.

Harman, W.N. and C.O. Berg. 1971. The freshwater snails of central New

York. With illustrated keys to the genera and species. Search,

Cornell. 1(4):1-68.

Henderson, J. 1929. The non-marine Mollusca of Oregon and Washington.

Univ. Colo. Stud. Ser. BioI. 17:47-190.

Herrington, H.B. 1962. A revision of the Sphaeriidae of North America

(Mollusca: Pelecypoda). Misc. Publ. Mus. Zool. Univ. Mich. 118:

1-74.

Liebman, H. 1960. Handbuch der Frischwasser und Abwasser-Biologie.

Biologie des Trinkwassers, Badewassers, Tischwassers, Vorfluters und

Abwasser. II. R. Oldenbourg, MUnchen, 1149 p.

20

Rawson, D.S. 1939. Physical and chemical studies, plankton and bottom fauna

of Okanagan Lake, B.C., in 1935 with appended data from adjacent

smaller lakes. Pp. 3-26 in: Clemens, W.A., D.S. Rawson and J.L. Mettugh.

A biological survey of Okanagan Lake, British Columbia. Bull. Fish.

Res. Board Can. 56:1-70.

Saether, O.A. 1970. A survey of the bottom fauna in lakes of the Okanagan

Valley, British Columbia. Techn. Rep. Fish, Res. Board Can. 196:

1-26.

_______ . 1971. Notes on general morphology and terminology of th.e

Chironomidae (Diptera). Can. Ent. 103:1237-1260.

Stockner, J.G. and G.D. Koshinsky. MS, 1971. Preliminary report on 1971

limnological conditions related to the Wood~Kalamalka Lakes problem.

14 p.

Stringer, G.E. 1967. Introduction of Mysis relicta Loven into Kalamalka

and Pinaus Lakes, British Columbia. J. Fish. Res. Board Can. 24:

463-465.

Table 1. Selected temperature, oxygen and Secchi disc visibility values in Ka1ama1ka and Woods Lake, 1971 (collected by CCIW, Burlington, Ontario) .

Ka1amalka Wood

Date Apr. 24 May 27 Aug 25 Apr. 24 May 28 Aug. 25

Secchi disc visibilit y , m 15.5 7.0 5.5 2.0 5.0 3.5

~mp °c Depth

m

1 4.5 10.7 21.9 6.1 16.9 21.4 5 4.5 9.0 17.6 6.0 15.6 21.4

10 4.4 7.8 12.0 5.8 9.3 15.0 15 9.5 25 4.3 5.8 5.2 4.2 4.7 5.3

28-30 4.0 4.7 5.2 50 4.3 4.9 4.8 78 4.2 90 4.5

100 4.5

~g 1

Depth m

1 13.6 11. 2 8.5 12.0 10.8 9.4 5 13.0 11. 4 8. 8 11.8 10.8 9.4

10 12.9 10.2 9.2 11. 0 12. 1 9.0 15 2 . 0 25 12.5 12.7 11.8 10.6 7.0 0.5

28-30 11. 2 5.2 0.8 50 13.0 12. 2 11. 0 78 13.5 90 11. 6

100 12.0

Table 2. The average number of bottom organisms 2 . Woods, Ka1ama1ka and Skaha Lakes. per m ~n

May 10-12 , 1971

Lake Woods Ka1ama1ka Skaha

Depth (m) 1-5 6.3 31.3 All All 1-4 13-18 100 All All 1-2 11-15 38-52 All All

Depths Depths Depths Depths Depths Depth;

No. samples 9 3 3 15 15 12 9 3 24 24 6 6 6 18 18

Stations 1,2,5 4 3 All Sta. % 6,9,10,11 7,8,12 13 All Sta. % 14.17 15,18 16,19 All Sta. , Nematoda 10 30 104 33 4.3 4 15 119 22 2.0 22 119 5933 2025 20.4

01igochaeta 79 548 0 157 20.9 141 888 104 416 38.3 1711 5044 15110 7288 73.4

Malacostraca 5 0 0 3 0.4 11 5 0 7 0.7 0 0 0 0 0.0

Chironomidae 588 904 30 539 71. 7 485 919 119 602 55.4 733 956 133 607 6.1

Pisidium 0 0 0 0 0.0 0 2S 0 9 0.9 0 0 0 0 0.0

Miscellaneous 35 0 0 21 2.8 11 64 0 30 2.7 37 7 0 15 0.1

All organisms 716 1481 133 753 100.1 652 1915 341 1087 100.0 2504 6125 21176 9935 100.0

Table 3 . NUJII,ber of specimens collected per tl"ipiicate saaple (67S CJI2

) in WoodLake. Kalamalka Lake and Skalla Lake. Numbers in brackets 'I: ohgodlaetes

identified to s pec'ies with certainty .

WOOD KALAMALKA SKAHA

-

"'- --' - - ' I ~ , ? , • 5 6 7 8 9 10 II 12 13 14 IS 16 17 18 19

1U " 4 1

Ch.iJtol1omw a.tte.n.tut...tnh Walk.

10 7 5

ChVwno""", an.tIvuIcUtuh ... type 14 1 2 2 " '8 2 1

ChVw""""", plum,,.uh type 2 38 1 1 " 2

Giyp.tJJtencUpu IPhy.tJJ.w.-cUpu) sp. 4 1

V~CJl.o.w.cUpU sp. 8 2 1 1 1

Oujp.tJJ.w.cUpu sp. 1

Oujp.tJJcla.dopehno. sp. 1 1 1

PaA1J.cia.dop<hna sp. 1 1 1 1

HIVVw,~ CWL.ti..t.ame.e..e.a..ta (Mal!.) 1

OujpWc1Wtonomuh sp. 4 1 2 2 3 2 1 3

S.tA..wch.i..JwltOmtLO h.i.6VUo type 1 2

Poiyped.<..e.um I POiypedJ.wn) sp. 1

Poiyped.<..e.wn (T-'UpoduM) cf. 0 cala.neu.m (Schaenk.) 1 1

Poiyped.<..e.wn IT-'UpoduMJ cf. .b.unu.ia.n.! (Townes) 1

Genus near Poiype.di...f.J.Jm 1

Phaenopoec.bta (T!Libelo.) 12 3 1 1 2 1

Phaenopoec.t-ul ISelt.ge>tU.a.) 1 1 2 " 2 2

PaM.tencUpeo sp. 16 1

P<UUtla.u.lVtbOILM ella. .ugMho .. twUl.ie (M~ 11 .J 1 1

P.be.udoch..Uwnomuo sp. 2

Stempelline.ila. 1 7 1 9 1 2 2 " Genus near Cf.ado.t.oJtljtaJt..h1.Ul or RheotanytaMul 1 2

PaJuLta.ny.t'..aJthuo sp. 2 1

C.i.d.do.w JtytaM uo sp. 1 53 I" 9 6 1 5

T aJty.ta..ou(U sp. 1 3 1 21 7 13 6 6 4 9 2 32 1

Hydrac<lrina indet 4

P-i...6 .i..cU..um sp. 5

r:.p i dida.c indet. 1 1

Stratiomyidae indet. 1

Cyclorrhapha indet. 1

No. of Specimens per triplicate (675 cm2) sample 2" 1 9 100 US 10 131 194 82 S3 31 62 23 48 576 1354 287 226 483

Hya.teU.o. d<-teCd (Sauss.)

H .. /l9eMit tunba.ta (Serv.) .

Cae..rt..i..6 sp.

8aetidae indet.

Trichoptera indot.

Piea. cf. ~~.ea. Fieb.

NlJJtpUl> sp.

OPWHJtvUl> sp.

Ch e.iD ruut.i.um s p .

Coleoptera indct.

BezUa. group

P'loc1.ad.Wh I P'lOc1.alUUl> J spp.

PMc1.ad.Wh I P.dDtanypUA J sp.

T JUene.mQJ1n.Unyi.a g ro up

Po.wuu.u:o. cf. iort9.i.mantu> (Kieff)

PM.tanypt..l.O cf. mauo (Zett. )

PllOcU.a.mUa. cf. olivate..a. (Meig .)

MonocUmnU/l f.!. bo..(hy­phdD (Kieff.)

He.tvr.OtM.MOc1.acUuD f.!. .ubpdD.Ul> (Kieff.)

Genus near Tw~"c1.a.d..i./..Ih

CJLi.co.topUl> "PlJJtdtM.cho­c1a.cU.t..I.O 1/ group

CJLi.co.topUl> "EUeM.CO.toPM" type

CrL-i.cotopuo "Tllichocla.d.i..uo" type

P.ect'loc1.acUUl> IPoeUAo­cio.cUuo) schlicnZl type

P. eUAoc1.acUuD I PHctM­ctad<..u.oJ octomaculatus type

PHctMc1.alUUl> I PoectM­ctacUUl> J sp.

" P <IAO.IUe 6 6 eM. eU.o. rt.<g "" "

"PaJla.h..i.e.66vU.-e.U.a. c.oJtl.lna..ta."

CluA.onomu.6 sp.

Ch.iJtDnomUh 6~Uh type

ChUtoll.omuo .6 emiAedu.C-tu.6 type

34 27 3S

26 2S

12

1l

10

Clt..Ut.onorltf.loi 4K.tIvulcOtU6 type I' ;8

ClWwno_ plWNJ .... type 38

GlJjp~und<peh IPFujtct£n-d<p .. ) sp.

V.i.CJWund<peh sp.

Oujp~.te.nd<p.., sp.

Oujptcc.£.M.ope.1n'<I. sp.

PaMc.£.M.opeima. sp .

HcuutiAchi.a. CUJt..t.i..tame.Ua..ta. (Mall .)

Oujptcchi.a.ono .... s p.

S.t.i.e-to chi.a.o no mill> hM.tIti.o t ype

PolJjpeWum I PolJjpedJ.um) sp.

PolJjpeWum I T,upoduM) cf . .6cala.newn (Schaenk.)

PolJjpedJ.um (T,upodUM.) c f . .6.unu.ta.n..6 (Townes)

Genus near PotljP~

Pho.e.no".ec.tAa (TIUbe.io. J 12

Phde.no". ec.tAa I SeA9e.n.t.i.a.)

P<WLtend<p .. sp. 16

P<WU:o.u.tVtb o.w.<.e.iia n.i.g ~oha.U;VUli.e (MIll! .)

P.6e.u.d.ochUtortOm~ s p.

S.temp~ne.iia

Genus neaT Cfa.dO:tattljto.JlAM or Rltr-ota.n.yta.lt.buh

PoJta..tMlj.t£vt6 Ill> sp.

Cta.dotaJty.to.M u6 sp . 53 I'

Tan!!~/..1.6 sp. 21 13 32

Hydracarina inde t

p .i.6.i.d.i.wo s p .

Empi di dac indN.

Stratiomyi dae indet.

Cy clorrhapha indet.

No. of Specimens per triplicate (675 cm2) sample 24 100 115 10 131 194 82 53 31 62 23 48 5 76 1 35 4 287 226 4 83

Table 4. Dead Mollusca in samples from Ka1ama1ka and Woods Lakes,

May 10-12, 1971

Gastropoda

Physa cf. jennesi skinneri Tay1.

Lymnaea stagnalis (L)

Lymnaea decampi . 6Streng)

Lymnaea cf. decampi juv.

Lymnaea e10des (Say)

Lymnaea columella (Say)

Lymnaea cf. proxima (Lea)

He1isoma anceps (Minke)

He1isoma trivo1vis (Say)

Gyrau1us def1ectus (Say)

Promenetus exacuous (Say)

Amnico1a 1ustrica Pi1s.

Va1vata sincera Say

Pe1ecypoda

Pisidium casertanum (Poli)

Pisidium compressum Prime

Pisidium ni tidum Jen.

Pisidium obtusa1e Pfeiff.

Pisidium walkeri Starki

6,7,12

7

Station No.

6,7,9,11,12

1,6,7,9,11,12

6,7,11,12

7,11

6,7,9

6,7,9,11,12

6,7,9,12

1,4,6,7,8,9,10,11,12

6,7,9,12

10

6,7,8,9,11,12

6,7,8,9,10,11,12,13

1,6,7,8,9,10,11,12

7

6,7,9,11,12,13

6,7,11,12

10---+-

13---i~-

7--t--

FIGURE 1. , DEGREE OF ENRICHMENT AS INDICATED BY

DISTRIBUTION OF OLiGOCHAETA

6-limnodri Ius profund icola

o-More than 1000 per m2 of 0ligochae1a I but less than 1000 per m2 of Limnodfilus hoffmeisteri

e-More than 1000 per m2 of Limnodrilus hoffmeisteri

• -I species of invertebrates or less per station

KALAMALKA LAKE

\, N

14

, \

----\--16e

--+-180

"''"'''''~-1706

~ -N-I

OA7~~+--

FIGURE 2.

DEGREE OF ENRICHMENT AS INDICATED BY DISTRIBUTION OF CHIRONOMIDAE

A - Protonypus ct. moria

Genus near Trissocladius

Cricotopus "Porotrichoclodius" d. alpicolo

0- Monodiomesa t.1. bothyphilo

Heterotrissoclodius t.1. subpilosus

Chironomus solinorius group

O-More than 100 Clodotonytorsus per m2

.-More than 145 Chironomus spp. per m2

.-2 species of Chironomidoe or less

KALAMALKA LAKE

~ 14

15.0 -N-I

--"---19

17.

~ 1/ ~

A

,r'

c FIGURE 3, A. "Parakiefferiella nigra", mentum, antenna and seta anteriores (SI).

B. "Paraklefferlella----coronata", ventral view of head capsule. C. Genus near Cladotanvtarsus or Rheotanytarsus, antenna. D. Genus near Polypedilum, deformed mentum.