Aquatic Chemistry Controlling Nutrient Cycling: Redox and O - Freshwater Ecology: Concepts and Environmental Applications - page 219

TABLE 11.1 Possible Effects of Increased UV on Primary Producers

Effect of increased UV Reference

Alters cyanobacterial migration in algal mats Bebout and Garcia-Pichel (1995)

Decreases photosynthetic rates of phytoplankton and periphyton Kinzie et al. (1998)

in high-altitude tropical lake
Decreases nitrogen uptake rates of plankton Behrenfield et al. (1995)

Lowers populations of consumers of the producers Bothwell et al. (1994), Häder et al. (1995)

Damage to DNA Jeffrey et al. (1996)

Damage to ability of cyanobacteria to fix nitrogen Kumar et al. (1996)

Minimal effects with increased dissolved organic carbon Morris et al. (1995)

Damages photosynthetic apparatus Nedunchezhian et al. (1996)

Harms stream mosses Rader and Belish (1997a)

Selects for tube building or mucopolysacharide-producing Rader and Belish (1997b)

diatoms
Has selective effects on competitive ability of different Francoeur and Lowe (1998), Vinebrooke

periphyton species and Leavitt (1999)

Alters response to nutrient enrichments Bergeron and Vincent (1997)

Decreases growth of Sphagnum in a bog Gehrke (1998)

Alters phytoplankton species composition Laurion et al. (1998)

Exacerbates the biotic effects of acid precipitation on lakes Yan et al. (1996)

activity, the O 2 can be consumed completely during a summer season of a
dimictic or monomictic lake (Fig. 11.12A).
The hypolimnia of eutrophic lakes tend to lack O 2 by the end of sum-
mer, and oligotrophic hypolimnia of monomictic or dimictic lakes retain at
least some O 2 . The greater deficit of O 2 in eutrophic lakes occurs because

400

300

200

100

0

0 10 20 30 40

Temperature ( 0 C)

FIGURE 11.10 Relationship between photosynthetic rate and temperature based on 94
measurements of stream epilithon production in 14 studies (reproduced with permission from
DeNicola, 1996).