Temporal changes and vertical distribution of macrophytes in Lake Kawaguchi

Abstract

The distribution of macrophytes in Lake Kawaguchi, Japan, was surveyed in August 1999 using a sampling anchor from a boat. The survey revealed that the present aquatic vegetation was composed of 17 submerged species, and no floating-leaved plants were present. The diversity of submerged plants and their vertical growth limits decreased progressively from the west to the east end of the lake. At the time of the survey, the dominant species was Elodea nuttallii (Planch.) St. John, which had once grown explosively in the mid-1980s in the lake, and except for Vallisneria asiatica Miki, all of the species commonly observed in the lake seem to have diminished their growth greatly. Among them, Potamogeton compressus L., which was the most dominant species in the lake before the invasion of Elodea nuttallii, had decreased most severely. It is suggested that the present state of aquatic vegetation in this lake was much influenced by the persistent growth of Elodea nuttallii as well as by environmental factors.

Response of Elodea Nuttallii (Planch.) H. St. John to Manual Harvesting in the North-East of France

“…E. nuttallii will probably have a similar invasion pattern than E. canadensis. A noticeable decline in E. nuttallii indeed was also reported after the peak of the outburst in JapanÕs lake (Nagasaka et al, 2002). E. nuttallii populations exhibited a genetic uniformity that made them vulnerable to attack by fungi or pathogens.…”

“…The spread of E. nuttallii seems to be the cause of the disappearance of Myriophyllum alterniflorum, in Northern Vosges stream (Thiebaut et al, 1997) and the regression of Potamogeton compressus in lake Kawaguchi (Nagasaka et al, 2002). However, the loss of biodiversity induced by E. nuttalliiÕs spread was not clearly established.…”

Changes in biomass and spatial distribution of Elodea nuttallii (Planch.) St. John, an invasive submerged plant, in oligomesotrophic Lake Kizaki from 1999 to 2002

“…St. John, native to temperate North America (Cook and Urmi-Köing 1985), was first observed in Japan in the early 1960s in Lake Biwa (Ikusima and Kabaya 1965). Since then, its explosive growth has been reported repeatedly (Kunii 1984a;Kurita and Minemura 1985a,b;Hayakawa 1986;Nagasaka et al 2002). The competitive advantage of E. nuttallii over native species has been explained by its high shade tolerance (Ikusima 1967), by its active growth in low water temperatures (Kunii 1981(Kunii , 1982, and by its high dispersal ability (Kunii 1984a,b).…”

A long-term eutrophication process observed from the changes in the horizontal distribution of profundal oligochaete fauna in mesotrophic-eutrophic Lake Kawaguchi, Japan

“…In the present study we were unable to collect these species in Lake Kawaguchi. In regions shallower than 5 m, however, there were many kinds of submerged plants and a dominant species, E. nuttallii (Nagasaka et al, 2002), which provided important habitats for oligochaetes. Th us, it is necessary to investigate the distribution of aquatic oligochaetes in more detail in the shallower regions of this lake.…”