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Serrano, Ignacio, 2005. Survival of Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.) exposed to episodic acidification during spring flood. SLU, Dept. of Forest Ecology and Management, Umeå. Umeå: SLU, Dept. of Forest Ecology and Management

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Abstract

Överlevnaden av lax (Salmo salar) och öring (Salmo trutta) under tillfälliga pH-sänkningar under snösmältningen studerades i tio vattendrag i norra Sverige. Olika hydrologiska parametrar mättes kontinuerligt och vattenprover för laboratorieanalys insamlades under försöksperioden. Undersökningens syfte var att utvärdera dödligheten hos öring- och laxyngel (1+) under snösmältningen genom fältstudier för att identifiera vilka variabler som bäst förklarar skillnader i överlevnad i vattendrag. Syftet var också att bestämma kritiska toxicitets gränser i vattendrag med naturligt höga DOC-halter. Under vårens smältperiod ökade koncentrationen av DOC kraftigt vilket orsakade en naturlig pH-sänkning och en ökning av aluminiumhalter. Detta resulterade i hög dödlighet hos den studerade fisken. Undersökningen visar att lax var mindre motståndskraftig mot låga pH-värden i vattnet jämfört med öring. Det insamlade materialet bekräftar även att pH och ANC/H+ kvoten utgör goda indikatorer på överlevnaden hos lax och öring. Studien indikerar vidare att fisk i vattendrag med höga DOC halter har högre överkevbad låga pH värden och oorganiska aluminiumhalter än fisk i vattendrag med låga DOC halter. Resultaten visar också att en kritisk kemisk pH-nivå kan fastställas för lax och öring i humusrika vattendrag (DOC >10mg/l). Enligt de kemiska observationerna av vattendragen indikerar detta att ca 40 % respektive 10 % av Krycklans 68 km2 stora avrinningsområde inte är lämpliga för lax och öring.

This study was designed to evaluate the survival of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) parr (1+) during the spring snow melt period in order to identify variables that best explain differences in fish survival among streams, and to define critical toxicity thresholds in organic rich waters. The experiments were carried out in 10 streams in northern Sweden. Different hydrological parameters were monitored continuously, and water samples for chemical analysis were collected throughout the experimental period. During the spring snow melt, DOC concentration increased strongly, causing a natural depletion of pH and an increase in total aluminium, which resulted in high fish mortality. Atlantic salmon was more sensitive than brown trout to acidic water in all streams during the experiments. Also, the mortality data confirmed that pH and ANC/H+ ratio constitute good predictors of Atlantic salmon and brown trout survival. The results also suggest that fish in DOC-rich streams can tolerate higher acidity and inorganic aluminium levels than fish in low DOC systems. Accordingly, a critical chemical threshold of pH (5.9 and 5.1) can be defined for Atlantic salmon and brown trout populations, respectively, in humic rich waters (DOC > 10 mg/l), about 0.3 pH units lower than for humic poor waters.

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This study was designed to evaluate the survival of Atlantic salmon (Salmo salar) and
brown trout (Salmo trutta) parr (1+) during the spring snow melt period in order to
identify variables that best explain differences in fish survival among streams, and to
define critical toxicity thresholds in organic rich waters. The experiments were carried
out in 10 streams in northern Sweden. Different hydrological parameters were monitored
continuously, and water samples for chemical analysis were collected throughout the
experimental period. During the spring snow melt, DOC concentration increased
strongly, causing a natural depletion of pH and an increase in total aluminium, which
resulted in high fish mortality. Atlantic salmon was more sensitive than brown trout to
acidic water in all streams during the experiments. Also, the mortality data confirmed that
pH and ANC/H+ ratio constitute good predictors of Atlantic salmon and brown trout
survival. The results also suggest that fish in DOC-rich streams can tolerate higher acidity
and inorganic aluminium levels than fish in low DOC systems. Accordingly, a critical
chemical threshold of pH (5.9 and 5.1) can be defined for Atlantic salmon and brown
trout populations, respectively, in humic rich waters (DOC > 10 mg/l), about 0.3 pH units
lower than for humic poor waters.

Main title:Survival of Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.) exposed to episodic acidification during spring flood
Authors:Serrano, Ignacio
Supervisor:Brännäs, Eva
Examiner:UNSPECIFIED
Series:UNSPECIFIED
Volume/Sequential designation:UNSPECIFIED
Year of Publication:2005
Level and depth descriptor:Other
Student's programme affiliation:Other
Department:(S) > Dept. of Forest Ecology and Management
Keywords:trout, salmon, salmo, acidification, pH
URN:NBN:urn:nbn:se:slu:epsilon-s-7413
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-7413
Subjects:Fisheries and aquaculture - General aspects
Language:English
Deposited On:03 Oct 2017 08:36
Metadata Last Modified:03 Oct 2017 08:36

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