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Potential fragmentation and loss of thermal habitats for charrs in the Japanese archipelago due to climatic warming
Author(s) -
NAKANO SHIGERU,
KITANO FUMIAKI,
MAEKAWA KOJI
Publication year - 1996
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1046/j.1365-2427.1996.d01-516.x
Subject(s) - archipelago , habitat , salvelinus , ecology , range (aeronautics) , habitat fragmentation , population , geography , global warming , fishery , climate change , environmental science , biology , fish <actinopterygii> , trout , materials science , demography , sociology , composite material
1. The upper thermal limits of the present distributions of two charr species, Dolly Varden, Salvelinus malma , and white‐spotted charr, S. leucomaenis , in streams of the Japanese archipelago were examined using groundwater temperature as an index of thermal condition. The lower limits of the altitudinal distributions of Dolly Varden and white‐spotted charr were delineated, respectively, by 8 and 16 °C groundwater isotherms. 2. The potential impact of future climatic warming on the geographical distribution, habitat extent and population fragmentation of each species was predicted at both the full archipelago and individual catchment levels. 3. For Dolly Varden, analysis at the full archipelago level indicated a loss of 27.6, 67.2, 79.6 and 89.6% of the current geographical range, respectively, for a 1, 2, 3 and 4 °C increase in mean annual air temperature. The present distribution area of white‐spotted charr would likewise reduce by 4.1, 20.5, 33.8 and 45.6%, respectively. 4. Based on the analyses of three individual catchments, one for Dolly Varden and two for white‐spotted charr, the lower habitat boundaries for the two charr species could be expected to rise increasingly to higher elevations in each catchment as warming proceeded. As a consequence, there would be large reductions in mean habitat area, with increasing habitat fragmentation followed by localized extinctions of the two species.