Press release 2012-12-10 at 10:00
|
|
|
|
Sebastian Valanko
Photo: Alf Norkko
|
“Continuous dispersal of small benthic invertebrates can help maintain diversity on the seafloor. Ecosystem functions that these benthic organisms provide may also contribute to recovery after a disturbance”, says researcher, MRes Sebastian Valanko working at the Finnish Environment Institute (SYKE). In his PhD thesis, which he is due to defend next week at Åbo Akademi University, he has studied dispersal of invertebrates and how they may migrate from one area to another.
Benthic invertebrates are important in many ways: they can oxygenate the sediment on the seafloor and recycle nutrients; in other words their functions can contribute to a cleaner sea.
Sebastian Valanko’s PhD thesis has quantified dispersal of benthic invertebrates for the first time in practice underwater. Such knowledge is important when assessing the role benthic invertebrates play in recovery after various disturbances. Once they arrive and re-establish, after a hypoxic event caused by eutrophication, they may help maintain favourable oxygen conditions. Information on dispersal can also be used when, for example planning marine protected areas.
“The continous small-scale dispersal of benthic invertebrates is either mechanical movement from one location to another, as a result of waves and currents, or active movement. Such knowledge is scarce, and it is not until now that such studies have been conducted in the Baltic Sea, due to the practical difficulties in actually measure dispersal in nature”, Valanko says.
In his field studies, Valanko used different types of trap to capture invertebrates dispersing at different sites, while in parallel measuring waves and currents. This has required some 1015 dives by Sebastian Valanko and his research team in the archipelago close to Tvärminne Zoological Station at Hankoniemi, south-western Finland.
Studies also investigated recovery of the seafloor at several sites over a one-year period.
“In response to small-scale disturbance, initial recruitment is by nearby-dominant species, after which other species will also arrive successfully from further away. Species differ in their dispersal strategies. In practice, this implies that if only one locality is protected it may not be sufficient to ensure that diversity is maintained as a whole. Other source locations are equally important, from which individuals continuously arrive and are thus also essential in maintaining diversity”, says Sebastian Valanko.
Sebastian Valanko’s PhD thesis complements more theoretical studies in ecology. It is essential to understand how and when individuals are dispersing relative to underlying environmental conditions within a region. Such information can be used, for example, when assessing the impacts of various disturbances to the seafloor.
PhD thesis
The public defence will take place on Wednesday, the 19th of December 2012 at 12 o’clock at Åbo Akademi University’s Department of Natural Sciences, in the Armfelt auditorium in Arken (Tehtaankatu 2, Turku, Finland). The opponent will be Professor Paul Snelgrove from Memorial University of Newfoundland, Canada and the custodian will be Professor Erik Bondsdorff.
PhD thesis
The PhD thesis will be published in the Åbo Akademi Universities series of Doctoral theses under the title “Dispersal and metacommunity dynamics in a soft-sediment benthic system: how well is the seafloor connected?” (Pohjaeläimien liikkuvuus ja niiden metayhteisödynamiikka meren pehmeillä pohjilla – kuinka hyvin meren pohja on kytkeytynyt?)
Photographs for media use:
For more information, contact
Researcher, MRes, BSc(Hons) Sebastian Valanko
Finnish Environment Institute SYKE, Marine Research Centre
Tel. +358 40 529 6145
E-mail: fistname.lastname@ymparisto.fi