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Abstract
Some ecophysiological variables of aquatic bryophytes transplanted from their original collection sites in the River Iregua (La Rioja, N. Spain) to two stations of different water quality were examined as indicators of organic pollution. The variables were chlorophyll and phaeopigment levels, some pigment indexes (OD665/0D665 - acidified, OD430/OD410, OD430/0D665 and OD480/0D665), net photosynthesis, dark respiration and tissue Nand P levels.
Net loss or cessation of uptake of Nand P, together with photosynthetic decline, were firstly detected as a consequence of organic pollution. Later, pigment composition was also affected, phaeopigment ratios being the most sensitive to organic pollution. Respiration did not show consistent changes. Tissue Nand P contents are particularly recommended as organic pollution bioindicators because of their applicability in a range of pollution intensities, species sensitivities and exposure periods and their direct physiological relationship to anoxia in waters.
Among the three transplanted species Jungermannia exsertifolia subsp. cordifolia was the most sensitive and Fontinalis antipyretica the least, whilst Brachythecium rivulare exhibited intermediate sensitivity. The effect of shoot structural characteristics on organic pollution sensitivity is briefly discussed.