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Viru-Peipsi veemajanduskava - Keskkonnaministeerium

Viru-Peipsi veemajanduskava - Keskkonnaministeerium

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3.1.2 Lämmijärv ja Pihkva järv<br />

35<br />

3.1.2 Lake Lämmijärv and Lake Pihkva<br />

• Peamiste bentostoiduliste kalade (latikas,<br />

kiisk) produktsioon oli üsna väike (10%).<br />

• Põhilise osa produktsioonist (68%) andsid<br />

planktontoidulised kalad. Varasematel aastatel<br />

oli nende osatähtsus <strong>Peipsi</strong>s tunduvalt<br />

suurem.<br />

The changes in fish fauna are still relatively small<br />

and the condition of fish fauna can be assessed<br />

at least as good. Yet attention should be paid to<br />

significant changes in the abundance of dominant<br />

species:<br />

• The biomass of predatory fish (mainly<br />

pikeperch, >10 cm perch and pike) is<br />

currently extraordinarily high but predatory<br />

fish form only a fifth of the lake’s total<br />

production.<br />

• Production of the main benthos-eating fish<br />

(bream, ruff) is rather small (10%).<br />

• Plankton-eating fish formed the biggest<br />

share of the total production (68%). In<br />

earlier years their share in Lake <strong>Peipsi</strong> was<br />

considerably higher.<br />

3.1.2 Lämmijärv ja Pihkva järv<br />

Kuigi Pihkva järv kuulub <strong>Peipsi</strong> järvega samasse<br />

järvistusse, on Pihkva järvel <strong>Peipsi</strong>ga võrreldes<br />

siiski mitmeid morfoloogiast ja vesikonna suurusest<br />

tingitud erinevusi. Pihkva järve vesikond on<br />

<strong>Peipsi</strong> omast järve pindala arvestades 2,5 ja järve<br />

mahtu arvestades 5 korda suurem. Pihkva järve<br />

keskmine sügavus on <strong>Peipsi</strong>st üle kahe korra<br />

väiksem. Seega on Pihkva järve toitainete suhteline<br />

koormus juba looduslikult <strong>Peipsi</strong> järvest tunduvalt<br />

suurem. Pihkva järve lõunaossa suubub<br />

Velikaja jõgi, mille suudmes asub ca 200 000<br />

elanikuga Pihkva linn. Velikaja jõe vooluhulk<br />

moodustab üle poole kogu <strong>Peipsi</strong>-Pihkva järvistu<br />

sissevoolust ja enamuse Pihkva järve omast. Pihkva<br />

linna paiknemine järve vahetus läheduses tähendab<br />

seda, et praktiliselt kogu linna reostus<br />

jõuab ka järve.<br />

Eelnevat arvestades ei saa Pihkva järve seisundi<br />

hindamisel aluseks võtta <strong>Peipsi</strong> järve jaoks<br />

morfoedaafilisel indeksil põhinevaid võrdlustingimusi.<br />

Pihkva järve jaoks ei ole teadlased fosforisisalduse<br />

hea ja rahuldava seisundi piiri kahjuks<br />

veel välja arvutanud. Pihkva järvega sügavuse<br />

poolest sarnase Võrtsjärve jaoks on ZBI teadlaste<br />

poolt hea ja rahuldava seisundi piiri tähistavaks üldfosfori<br />

kontsentratsiooniks välja pakutud 46 mg P/l<br />

(<strong>Peipsi</strong> jaoks 34 mgP/l). Morfoedaafiline indeks<br />

arvestab järve keskmist sügavust ja vee karedust,<br />

3.1.2 Lake Lämmijärv and Lake Pihkva<br />

Although Lake Pihkva belongs to the same lake<br />

system as Lake <strong>Peipsi</strong>, it is still different in several<br />

respects due to its morphology and the size<br />

of its catchment area. The catchment area of<br />

Lake Pihkva is 2.5 times bigger than that of Lake<br />

<strong>Peipsi</strong> in relation to the surface area and 5 times<br />

bigger in relation to the volume of the lake. The<br />

average depth of Lake Pihkva is more than twice<br />

smaller than that of Lake <strong>Peipsi</strong>. The relative nutrient<br />

load of Lake Pihkva is thus already naturally<br />

much bigger than in <strong>Peipsi</strong>. Into the southern<br />

part of Lake Pihkva flows the River Velikaja, at<br />

the mouth of which there is the town of Pihkva<br />

with appr. 200 000 inhabitants. The flow of the<br />

river forms over a half of the inflow of the entire<br />

<strong>Peipsi</strong>-Pihkva lake system and a vast majority of<br />

that of Lake Pihkva. As Pihkva Town is located in<br />

immediate vicinity of the lake, basically all of the<br />

town’s pollution reaches the lake.<br />

Considering the above, the reference conditions<br />

identified for Lake <strong>Peipsi</strong> on the basis of the<br />

morphoedaphic index cannot be taken as a basis<br />

for assessing the status of Lake Pihkva. The limit<br />

value between good and moderate status in<br />

terms of phosphorus content has unfortunately<br />

not been calculated for Lake Pihkva yet. For Lake<br />

Võrtsjärv, which has a depth similar to that of<br />

Lake Pihkva, the scientists of the Institute of Zoology<br />

and Botany (ZBI) have suggested that the

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