Återhämtning av vattenmiljön efter avvecklandet av fiskodling: uppföljning av återhämtningsstatus vid Andersö och Järsö samt vid en ny lokal, Bergö

D4 Publicerad utvecklings- eller forskningsrapport eller studie


Interna författare/redaktörer


Publikationens författare: Anniina Saarinen
Förläggare: Åbo Akademi, Forskningsrapporter från Husö biologiska station
Publiceringsår: 2017
ISBN: 978-952-12-3492-7


Abstrakt

A follow up study of the recovery of the aquatic environment after
cessation of fish farming at Andersö and Järsö was conducted summer
2016. Results were compared with a previous study in the
areas from summer 2003. In addition, a recently terminated fish farm at
Bergö was studied for future monitoring purposes. Water temperatures
2016 were in general lower and the amount of organic matter higher than
2003. Recovery of the aquatic environment was best explained with the
benthos data. Benthos at both Andersö and Järsö showed signs of recovery
after cessation of fish farming. At Andersö, the stations further away
from the former fish farm, outside the Snäckö bay, were showing a
recovery in abundances, biomass and diversity, but in general all
stations showed a change from Chironomidae dominated communities
to Macoma balthica dominated communities, which can be an indication of
recovery. At Järsö area, stations farther away from the former fish
farm had higher total abundances and biomasses than 2003. The
stations closest to the former fish farm were still degraded,
consisting mainly of Chironomids, but the total abundances and
biomasses had clearly increased also there, which can be a sign of a
next step of succession after colonization of opportunistic species. It
is likely that the
relatively good water circulation in both Andersö and Järsö area
has had an effect on the recovery, but possibly also the fact that
Marenzelleria spp. had become more abundant in the areas and therefore
possibly improved the oxygen conditions in the sediment. Nevertheless,
reference stations both at Andersö and Järsö showed a slight decline
in diversity and species evenness which might be a sign of an
overall worsening in the areas water quality as a result of
eutrophication or a result of natural fluctuations in the environment.
At Bergö, the stations closest to the

former fish farm were most degraded, with low abundance,
biomass and diversity of benthos. The stations farther away (including
the reference station) and one station close to the fish farm on the
western side were in better condition, but the diversity was generally
low.


Senast uppdaterad 2019-24-10 vid 03:48