kurenkov, 1966. the influence of volcanic ashfall on biological processes in a lake

8/13/2019 Kurenkov, 1966. the Influence of Volcanic Ashfall on Biological Processes in a Lake.

1/4

426 NOTES AND COMMENTductor cable and FM telemetry for oceano-graphic research. ARON,W.,N. RAXTER, R. NOEL,AND W. ANDREWS.

I

REFERENCES

F. BOURBEAU W.D. CLARKE W. ARONGM Defense Research Laboratories,General Motors Corporation,Santa Barbara, California 93107.

1964. A description of a discrete depthplankton sampler with some notes on the tow-ing behavior of a B-foot Isaacs-Kidd midwatertrawl and a one-meter ring net. Limnol.Oceanog., 9 : 324-333.

THE INFLUENCE OF VOLCANIC ASHFALL ON BIOLOGICALPROCESSES IN A LJIKE

In the autumn 1955, in Kamchatka beganthe eruption of Mount Besymjanny, one ofthe volcanoes situated in the neighborhoodof Mount Kluchevskoy. The culmination ofthe eruption was reached on 30 March 1956.A violent explosion occurred, such as hadnot been observed in Kamchatka for at leasthalf a century. By its force and character,the eruption of Mt. Besymjanny is thoughtby the volcanologists ( Gorshkov 1958) tobe most similar to the eruption of the fa-mous Alaskan volcano Katmai in 1912.The explosion of Mt. Besymjanny de-stroyed the peak of the volcano and sentan immense heap of ash to an altitude ofover 40 km. The ash was carried by thewind to the northeast and covered thevernal thawing snow in the surroundings ofthe volcano with an ash layer that in placesreached a considerable thickness; even ata distance of 80 km to the northeast it was20 mm deep ( approximately 20 kg/m2 ) .The eruption greatly altered the sur-rounding landscape and had a disastrous re-percussion on the regimen of watersheds inthe valley of the Bolshaya Khapiza River.The fauna of the water bodies also suf-fered from the after effects of the eruption( Kurenkov 1957); in the basin of the Bol-shaya Khapiza young salmon were killedand the breeding conditions deteriorated.Either and Rounsefell ( 1957) noted therelationship between the after effects ofvolcanic eruptions and the reproduction ofsalmon in the lakes of Alaska. They ana-lyzed the catches of sockeye salmon, On-

corhynchm nedca Walb, in some lakes ofAlaska after the Katmai eruption and dis-covered that, in the lakes subjected to ash-fall, several broods of sockeye were verysmall, but that after a short time the popu-lation recovered and even increased in num-ber.Those authors think that in the yearsfollowing the eruption environmental con-ditions in the lakes became very favorableto the sockeye and suggest that this mayhave been caused by a better food supply,owing to the fertilization of lake waters byvolcanic ash. In corroboration of this pos-sibility they refer to the data obtained byGriggs ( 1920), who, on the basis of investi-gations of plant growth in the zone of ash-fall, established that during the first twoyears following the eruption, growth wasdepressed, but that after the second year anabrupt increase in growth occurred.

Goldman ( 1961)) h owever, believed thatthe intensity of productive processes in thelakes could not have been greatly increasedby the ashfall, because, according to hisanalyses, the Katmai ash is very low in bio-genes, particularly magnesium. The impor-tance of this element in stimulating thedevelopment of phytoplankton was experi-mentally verified by him on artificial cul-tures. This made Goldman doubt thecorrectness of the suggestion of Either andRounsefell, and no definite answer has beenprovided to the question.We now have at our disposal the resultsof some observations on the development of


2/4

NOTES AND COMMENT 427TABLE 1. Results of the analysis of a waterextract of the Besymjanny volcanic ash (accordingto Touaroz;a 1958)

NH,mg/100 g mg-equiv.

7.20 0.33Na 5.15 0.23K 1.68 0.04Mg 10.20 0.84Ca2+ 81.20 4.05Fe+ 2.22 0.08Fe3+ 2.18 0.12

Cl- 55.04 1.55FIG. 1. Region subjected to ash _ __(fall. 1) actives; 2) extinct volcanoes; 3) major directionsIl. ,,;I A\ ,ccl,-,,c~

so,2-HC03- 198.4024.404.120.40

Total anions 277.84 6.07plankton in one of the water bodies sub-jected to ashfall during the eruption of Mt.Besymjanny.West-northwest of the volcano, at a dis-tance of 80 km, lies Lake Asabatchye, whichhas its own local stock of sockeye. The lakeis in a glen in the eastern range system, andis connected with the Kamchatka River bya short ( 12 km) river ( Fig. 1) . The lakehas a surface area of 62 km2, its basin hasan area of 340 km2.As an approximation, nearly 1 x lo6 met-ric tons of ash were deposited on the lakeand on its basin.According to the data of Tovarova( 1958)) a water extract of 100 g of ashcontained 400 mg of salts with a prevalenceof calcium and magnesium salts (Table 1) .Unfortunately, no determinations weremade of phosphorus and nitrates.Plankton samples are available whichwere collected in the lake in the years be-fore the eruption ( 1949, 1953-1956)) in theyear of the eruption, and in the followingyears up to 1964. Unfortunately, samplingwas not always systematic enough, but theanalysis of these samples reveals a well de-fined picture of quantitative changes in thedevelopment of limnoplankton.

In Lake Asabatchye, diatom phytoplank-ton is prevalent, the most common forms be-ing Melosira italica, Asterionella formosa,and Synedra ulna.

HnS 0H2Si03 4.59Total CO, 211.20Total solids 411.80PH 5.00

The ice cover on the lake breaks up inmiddle or late June, and the maximum de-velopment of diatoms is usually observed inJuly and August. In the samples collectedbefore 1965, the number of diatoms in theplankton during the maximum period wasseldom more than 1 x lo4 cells/liter, andusually far less.In the year of ashfall ( 1956), the contentof vernal samples taken from under the icegave no cause to expect any importantchanges in the usual course of phytoplank-ton development; algae were almost absentin the March samples. But in June, thenumber of diatoms rose to 4 x lo4 cells/liter and in August reached almost 1 x lo6cells/liter, a value never before recordedduring the period of observations.In the following years, the number ofalgae during the peak periods decreased butremained on a relatively high level. It isdifficult to say at present whether this long-term effect was caused by the ashfall of1956 only, or by later ashfalls; slight out-bursts of ash by Mt. Besymjanny and alsoby Mt. Kluchevskoy were observed in lateryears.


3/4

428 NOTES AND COMMENT

FIG. 2. Changes in abundance of diatoms ( 1) and cyclops (2) in Lake Asabatchye, 1949-1964.

Unfortunately, no detailed hydrochemicalinvestigations were carried out in the lake.The few available analyses (Table 2) showthat no noticeable changes have occurredin the content of bicarbonate, calcium, mag-nesium, and total hardness.The unusual development of algae mayhave been stimulated by the considerablequantities of iron received by the lakewaters, as has been convincingly demon-strated by Gusseva ( 1947, 1952) in studiesof the Uchinsky reservoir.The secondary link of the trophic chain inthe lake are cyclops ( Cyclops scutifer Sars ) .They reach their maximum abundance inthe autumn ( September-October). Thehighest number of cyclops in samples takenbefore the eruption was 30 specimens/liter( autumn 1953).During the first period of maximum de-velopment of algae ( 19%1959)) the num-

ber of cyclops declined to 5 specimens/liter,but in 1959 it began to increase and reachedits maximum in 1963 with 240 specimens/liter ( Fig. 2).Let us consider the condition of the sock-eye stock in Lake Asabatchye. If Eitherand Rounsefell are right in concluding thatthe first years after ashfall have an adverseeffect on the yield of sockeye, then a de-crease in the number of adults returning tothe lake to spawn would have been ex-pected in the years 1960-1964. Accordingto A. G. Ostroumov, who is yearly conduct-ing observations ( aerovisual and aerophoto-graphic) of the occupation of the sockeyespawning grounds, such a decrease doesactually take place ( Fig. 3).It must be kept in mind that the sockeyeof Lake Asabatchye are subjected to an in-tensive and not always uniform fishing byJapanese fishermen, so that caution is neces-

TABLE 2. Analyses of uater from Lake Asabatchye (middle of the lake, surface)

Date -Totalsolids SiO,

Bicarbonateco2 CaO

(mg/liter)

Mg0 Cl Totalhardness

( degrees )24 March 1954 1.5 7.2 31.1 13.8 4.9 5.7 1.8215 March 1956 0.1 32.0 14.8 5.6 2.2122 Aug 1956 16.8 32.0 15.2 4.7 2.18


4/4

NOTES AND COMMENT 429

FIG. 3. Occupation of sockeye spawninggrounds in the basin of Lake Asabatchye in1957-1964.

sary in determining causes of fluctuationsin the abundance of the local stock. Thereis, however, no evidence contradicting theassumption of a deleterious effect of ashfall.

If we assume that the further biologicalprocesses in the lake will follow the samecourse as in the lakes of Alaska, then it maybe expected that in the next few years thestock of sockeye salmon will increase innumber owing to favorable changes in theconditions of reproduction. This is alsoindicated by an improvement of the lakesupply of food plankton, and there is someevidence that the biomass of benthos (Oli-gochaeta, Pontoporeia, Chironomidae, andothers) has also become more abundant, incomparison with the data from the bottomfauna survey of 1953-1954.

MASS IMORTALITY INThe interesting phenomenon of suddenand devastating mass mortalities in popula-tions of marine animals has been discussedby Brongersma-Sanders ( 1957). She listsseveral elements known to cause such mor-talities, including noxious water blooms,lack of oxygen, vulcanism, earth- or sea-quakes, vertical currents, severe storms,changes in temperature, and sudden changes

in salinity. During the winter of 1964-1965,1 This investigation was supported by NationalInstitutes of Health Grant AI-05358.

CONCLUSIONThere is as yet no unanimous opinionconcerning the fertilizing effect of volcanicash in the lakes situated in zones of activevolcanism. But observations on the devel-opment of plankton in Lake Asabatchyecompel us to answer this question in theaffirmative. I. I. KURENKOVPacific Research Institute ofMarine Fisheries and Oceanography(TINRO),Petropavlovsk-on-Kamchatka Branch,USSR.

REFERENCESEICHER, G., AND G. ROUNSEFELL. 1957. Effectsof lake fertilization by volcanic activity onabundance of salmon. Limnol. Oceanog., 2:70-76.GOLDMAN, C. 1961. Primary productivity andlimiting factors. Verhandl. Intern. Ver. Lim-nol., 14: 120-124.GORSHKOV, G. S. 1958. An unusual eruption atKamchatka. Priroda, 1: 61-68.GRIGGS, R. F. 1920. The recovery of vegetationat Kodiak. Ohio State Univ. Bull. 24. 15 p.GUSSEVA, K. A. 1947. Causes of periodicity in

the development of phytoplankton in theUchinsk reservoir. Byul. Mask. ObshchestvaIspytatelei Prirody, Otd. Biol., 52: 49-61.-. 1952. Water bloom, its causes, prog-noses and control. Tr. Vses. Gydrobiol. Obsh-chestva Akad. Nauk SSSR, 4: 3-92.KURENKOV, I. I. 1957. Volcanic influence uponthe fluvial fauna. Priroda, 12: 49-54.TOVAROVA, I. I. 1958. On the evacuation ofwater-soluble substances from the piroplasticsof the volcano Besymyannyi. Geokhimiya,n.f., 7: 686-688.

A BIVALVE MOLLUSCSI observed an intensely localized mortalityof a marine mollusc that depended upon acombination of two of the factors listedabove. On La Jolla Beach, Todos 10s SantosBay, near Ensenada, Baja California, part ofa numerous population of the bean clam,Donax gouldi Dall, suffered decimation byexposure to the untempered heat and fresh-water of a hot-spring area when it was un-covered by ebbing spring tides.The bean clam inhabits 3,200 km of sandyocean beaches of California and Mexico. Itoccurs mainly in the intertidal zone, some-

kurenkov, 1966. the influence of volcanic ashfall on biological processes in a lake

Documents