Use of stable isotope analysis to evaluate the possible impact of fish migration on a lake biomanipulation

✍ Scribed by Jari Syväranta; Tapio Keskinen; Heikki Hämäläinen; Juha Karjalainen; Roger I. Jones

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 182 KB
• Volume: 18
• Category: Article
• ISSN: 1052-7613
• DOI: 10.1002/aqc.892

✦ Synopsis

1. A lake restoration project involving mass fish removals was started to improve further the water quality of a lake recovering from severe eutrophication. The effectiveness of such biomanipulation as a lake management option could be compromised if removed fish are rapidly replaced by large-scale immigration from a connected lake.

2. Stable isotope analysis (SIA) was used to examine the migrations of perch (Perca fluviatilis L.) and roach (Rutilus rutilus (L.)) between two connected lakes in central Finland, Jyva¨sja¨rvi and the larger Pa¨ija¨nne. Baseline d 15 N signatures in primary consumers were significantly higher in Jyva¨sja¨rvi and this difference was reflected further up the food chain in fish.

3. Spring fish spawning migrations from Pa¨ija¨nne resulted in a significant decrease in mean d 15 N signatures of both perch and roach in the adjacent part of Jyva¨sja¨rvi, but by summer these mean d 15 N signatures in fish muscle tissue had increased again to match those in the rest of the lake. d 13 C signatures of both fish species were more variable and were of less value for tracking fish migrations.

4. A robust discriminant analysis was used to classify perch and roach caught from Jyva¨sja¨rvi into fish originating from either Jyva¨sja¨rvi or Pa¨ija¨nne. The greatest proportions of immigrant perch and roach in Jyva¨sja¨rvi were observed in spring 2004 (71% and 56%), when biomanipulation of Jyva¨sja¨rvi had started. Immigrant fish percentages in the following spring were considerably lower (24% and 14%, respectively), most likely due to effective biomanipulation.

5. Results indicate that the current biomanipulation has decreased the extent of the spring migration, and that immigrant fish have not significantly repopulated Jyva¨sja¨rvi after the intense fishing. More generally, the data illustrate how stable isotopes offer the possibility to track migrations of common fish species between adjacent freshwater lakes.