Search results for "Trophic state index"
showing 4 items of 14 documents
Upstream migration activity of cyprinids and percids in a channel, monitored by a horizontal split-beam echosounder
2003
A 200 kHz digital echosounder (HTI) with two split-beam transducers was aimed horizontally to monitor the upstream migration activity of fish, from 24 April to 28 June, in Aijalansalmi channel (mean width 35 m, length 700 m, and maximum depth 5 m) from large mesotrophic Lake Paijanne to small eutrophic Lake Jyvasjarvi. This study was part of a larger project which aims to analyse the movement of commercially unimportant fish species and reduce the abundance of these fish in L. Jyvasjarvi. Catch samples were collected with a trap net located immediately upstream from the acoustic beams. The most common species in the catch were roach (Rutilus rutilus), perch (Perca fluviatilis), bream (Abram…
Ergasilid copepods as parasites of perch Perca fluviatilis and roach Rutilus rutilus in Central Finland: seasonality, maturity and environmental infl…
1992
A total of 1255 roach Rutilus rutilus (L.) and 866 perch Perca fluviatilis (L.) from four interconnected lakes in Central Finland differing in trophic status and pollution level were studied for parasitic ergasilid copepods between August 1985 and December 1988. In addition, 109 whitefish (Coregonus sp.) were studied from one of the lakes. Four ergasilid species were found: (the prevalence and intensity/fish, respectively, for the whole material are given in parentheses) Ergasilus briani (16·9%, 0·5), Neoergasilus japonicus (15·6%, 0·4) and Paraergasilus longidigitus (2·1%, 0·02) on the roach and Ergasilus sieboldi (9·9%, 0·1) and P. longidigitus (4·9%, 0·05) on the perch. Logit analysis wa…
Assessment of the ecological status of transitional waters in Sicily (Italy): first characterisation and classification according to a multiparametri…
2010
A 1-year cycle of observations was performed in four Sicilian transitional water systems (Oliveri-Tindari, Cape Peloro, Vendicari and Marsala) to characterise their ecological status. A panel of variables among which trophic and microbial (enzyme activities, abundance of hetetrophic bacteria and of bacterial pollution indicators) parameters, were selected. Particulate organic carbon (POC) and nitrogen (PON) and chlorophyll-. a (Chl-. a) contents defined the trophic state, while microbial hydrolysis rates and abundance gave insights on microbial community efficiency in organic matter transformation and on allochthonous inputs. To classify the trophic state of examined waters, the synthetic t…
A validated bioenergetics model for ruffeGymnocephalus cernuusand its application to a northern lake
2008
A bioenergetics model was constructed for ruffe Gymnocephalus cernuus, and the model was used to estimate the food consumption of a native G. cernuus stock in Pyhajarvi, a large mesotrophic lake in south-west Finland. The parameters for the bioenergetics model were determined through laboratory experiments conducted at several temperatures between 5 and 22° C for different sized G. cernuus (from 6 to 27 g). The model was verified and validated with independent laboratory growth experiments. The validated model was applied to field data from Pyhajarvi to estimate the food consumption of G. cernuus and its effects on the zoobenthos community during the years 2002–2004. The total annual food c…