Image Credit: Tiit Hunt, CC BY-SA 3.0, Image Cropped

Guest Post by Theresa Henke

First record of niche overlap of native European plaice (Pleuronectes platessa) and non-indigenous European flounder (Platichthys flesus) on nursery grounds in Iceland (2020) Henke et al., Aquatic Invasions, In Press

The Crux

Determining whether or not an introduced species is invasive is important, as it determines whether or not management steps need to be taken to slow or eliminate any negative impacts it might have on the local ecosystem. In Iceland, 15 introduced species have been recorded over the past decades but only six of them are currently classified as invasive or potentially invasive. One of these potentially invasive species is the European flounder (Platichthys flesus), a flatfish commonly found in coastal waters of Europe. The flounder is a catadromous fish, meaning it spawns in marine habitats but has the ability to survive in freshwater streams as well.

In 1999, the flounder was firstly identified in Icelandic waters in the southwest of the country. Since then it has rapidly spread clockwise around the country. Currently, it can be found in every part of Iceland, mostly in estuaries but also up in rivers and lakes. Juvenile flounder can be found on nursery grounds in shallow, brackish waters where they overlap with juvenile European plaice (Pleuronectes platessa). Plaice is a commercially important flatfish species native to Iceland. Despite the knowledge of the flounder’s arrival in Iceland in 1999, not much research has been conducted on the impact of this potentially invasive species.

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