The disintegration of populations of underwater plants in soft water lakes enriched with acidic organic matter

Abstract

The characteristics of habitats, individuals and populations of four submerged macrophytes, Lobelia dortmanna L., Isoëtes lacustris L., Sphagnum denticulatum Brid. and Fontinalis antipyretica Hedw., were studied in 12 soft water oligohumic lakes which had no inflow of allochtonic DOM and the DOC concentration in the water was <4.0 mg C dm -3 and 13 humic lakes enriched with allochthonous dissolved organic matter (DOM) from drained peat bogs and ranging in DOC water concentration from 4.1 to 44.0 mg C dm -3 . The analyses of population disintegration were conducted basing on characteristics of individuals (size, habitat, fertility) and populations (aggregation density index, settlement index of the population area). The settlement index of the population area for Lobelia, Fontinalis, Isoëtes, Sphagnum decreased from 8.4 to 6.2 g d.w. m -2 , 4.6 to 0.01 g d.w. m -2 , 85.4 to <0.001 g d.w. m -2 and 39.3 to 7.2 g d.w. m -2 , respectively. Similar trends were observed in aggregation density. The general pattern of the disintegration of populations of these species was always similar. It was independent of the source macrophytes drew resources from or their susceptibility to environmental changes. Individuals began to be eliminated from the deep and central parts of the population area. The remainder of the populations, which persist in the shallowest, best-illuminated part of the area, are themselves endangered by disturbances caused by wavy motion. The only populations of submerged macrophytes which can survive in polyhumic lakes under such conditions are those which are resistant to disturbances common in the shallow littoral (Lobelia dortmanna, Fontinalis antipyretica).KEY WORDS: soft water lakes, macrophytes, DOM, disturbance, population structure, Isoëtes lacustris, Lobelia dortmanna, Sphagnum denticulatum, Fontinalis antipyretica.pes of ecosystems (Faliñski and Venanzoni 1991; Gillet and Gallandt 1996). However, in no other ecosystem is the vegetation structure as simple or has as few species as aquatic ecosystems do. The main element of this structure are dominant aggregations. They have their own rhythm of variations in abundance and density (Szmeja 1994a, b). As such, they are not only structural, but also functional vegetation units. Therefore, the aggregation density and the settlement index of the population area are useful characteristics in the study of the mechanisms of the disintegration of underwater plants populations that are under anthropogenic pressure.It was presumed that since the dominant macrophytes in soft water lakes have diverse plasticity reaction patterns and life strategies, in the sense that Grime proposed (1979), the extinction of species will vary in lakes supplied with DOM. It is hypothesized that the intensity of population collapse in lakes enriched with allochthonous acidic DOM depends on the degree of habitat transformation, the location in the littoral of the population area and life strategy of the species. It was also the intention of this paper to determine whether ...

Climate driven changes in the submerged macrophyte and phytoplankton community in a hard water lake

“…In this lake, changes in other physicochemical parameters of the water environment, such as decreased conductivity and increased water color correlated with DOC, led to the retreat of charophytes and their replacement by vascular plants and bryophytes. Similar effects were observed in waters with artificially increased concentrations of humic substances (Szmeja and Bociąg, 2004). These parameters also influenced the biomass and structure of the phytoplankton community, especially the domination of nonflagellated species in the DP and flagellated species in the WP.…”

“…Stoneworts disappear after increased DOC, and they are often replaced by bryophyte F. antipyretica, which is tolerant to light deficiency and wave action. Thus, it colonizes shallow parts of lake bottoms if light is limited in the water due to humic substances (Szmeja and Bociąg, 2004). This species is tolerant to environmental conditions and can inhabit water with varying levels of trophy, transparency, hardness and reaction (Karttunen and Toivonen, 1995).…”

“…The occurrence of charophytes in lakes is mostly affected by nutrient enrichment; however, many changes in this macrophyte group are not clearly correlated with increased lake trophy (Bociąg et al, 2011;Kłosowski et al, 2006). Due to the high sensitivity of charophytes to humic substances in water (Szmeja and Bociąg, 2004), we predicted that many transformations of the charophyte vegetation are governed by variations of the DOC concentration caused by natural, climatic factors.…”

Biomass allocation to anchoring structures in the aquatic macrophytes from the subcontinental and Atlantic climates in Europe

“…Barko and Smart 1986;Duarte and Kalf 1990;Szmeja 1994a;Keddy et al 2001;Heegaard et al 2001;Szmeja and Boci¹g 2004), and much less frequently on comparative analyses of such relations in the macroscale, for example in geographically distant populations from the same climate or from different climatic zones (Phillips et al 1983;Jacobsen and Terneusb 2001;Santamaría and García 2004). Comparative studies of aquatic macrophytes in the macroscale could become a source of information on the effect of climate in general or its secondary effect on life strategies and evolution of this plant group.…”

The historical development of vegetation of foreshore mires beside humic lakes: different successional pathways under various environmental conditions

“…are typical of humic lakes. High concentrations of acidic humic matter and low pH eliminate submerged macrophytes (Farmer, 1990;Szmeja & Bocia˛g, 2004). Thus, in humic lakes macrophytes consist almost exclusively of nympheids, and in the most acidic lakes macrophytes are absent (Ga˛bka et al, 2004).…”