Fish reproduction and the impact of acidification in the Kyr�njoki River estuary in the Baltic Sea

Abstract

SynopsisSeveral freshwater species use the Kyronjoki River estuary as a spawning and nursery area. The main reasons for this seem to be the morphology of the estuary, the abundance of shelter provided by aquatic macrophytes, high food production and favourable temperature conditions. Acidification of the estuary due to drainage from acidic soils has made part of the estuary unsuitable for fish reproduction. In addition, year to year fluctuations in the acidity of the estuarine water have affected the reproductive success of several species. The severity of the effects of the acidification at the population level is determined by the spatial and temporal distribution of the larvae and juveniles.

Effects of boating activities on aquatic vegetation in the Stockholm archipelago, Baltic Sea

“…These shallow inlets are the main habitat for several brackish water plants and endangered charophytes (Blindow, 1994(Blindow, , 1995Wallstro¨m and Persson, 1999). The occurrence of dense vegetation is one of the main factors attracting spawning adults, larvae and juvenile fish (Urho et al, 1990;Sandstro¨m and Kara˚s, 2002a).…”

Chemical composition of cabbage (Brassica oleracea L. var. capitata) grown on acid sulfate soils

“…Exposure of the formerly stable iron sulfides to air (as a result of drainage practise) triggers oxidation and consequently generation of large quantities of sulfuric acid (H 2 SO 4 ) and sulfide-and silicate-associated metals (e.g., Al, Cd, Mn, Ni;Lin et al, 2001;Burton et al, 2006Burton et al, , 2008. Several previous investigations have shown that the mobilized metal-rich acidity is readily flushed out to adjacent drains and waterways by rainfall and snowmelt with profound detrimental effects on aquatic biota (Urho et al, 1990;Callinan et al, 1993;Hudd, 2000;Powell and Martens, 2005). The degradation of the water quality in these AS soil-affected aquatic ecosystems is reflected by ecotoxicological effects on aquatic plants, macroinvertebrates, and fish, as impoverished species richness and absence of sensitive species (Nyman et al, 1986;Meriläinen, 1989;Vuori, 1996;Hyne and Wilson, 1997;Kjellman, 2003;Gosavi et al, 2004).…”

Effects of acidification on 0+juvenile fish diversity and abundance in River Kyrönjoki, Finland

“…Nymphaeid biotopes, predominantly Nuphar lutea (water lily), is dense macrophyte vegetation, and samples taken through the vegetation showed it to be a significant nursery for most of the freshwater fishes found in the river (Urho et al, 1990;. These biotopes form 2-10 m broad strings along the shores in the lower reaches, constituting more than 70% of the macrophyte vegetation.…”

“…Effects of downstream migrations and larger habitat shifts (Urho et al, 1990;Urho, 1996), were minimized by concentrating the seining period to the middle of the summer (late July). The seining period was concentrated to as few days as possible in order to minimize the effects of significant mortality among 0 + juvenile fishes, and to optimize the efficiency of the gear in relation to the size selectivity of the gear .…”