ISSN:
1573-5117
Keywords:
epilithon
;
periphyton
;
zinc
;
glucose respiration
;
protein
;
carbohydrate
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Artificial streams were used to study the effect of chronic zinc dosing (0.00, 0.05 or 1.00 mg Zn l−1) on epilithic communities during summer and early fall, 1984 and 1985. Following zinc addition, epilithon was periodically measured for 14C-glucose and 14C-glutamate respiration, ash-free dry weight (AFDW), protein, carbohydrate, chlorophyll a (Chl a), pheophytin a (pheo a), and colony forming units (CFU) on zinc amended and unamended media. Transient peaks in glucose respiration rates mg−1 protein and AFDW occurred within 5 to 10 days in streams dosed with 1.0 mg Zn l−1 and coincided with decreases in AFDW, protein, carbohydrate, Chl a, and pheo a. Respiration of glutamate did not show a significant response to dosing (α = 0.05). Epilithic plate counts demonstrated more total and zinc-tolerant CFU in dosed than in control epilithon after 20 days. After 30 days, greater biomass and lower protein: carbohydrate ratios were evident in epilithon dosed with 1.0 mg Zn l−1 compared to unamended treatments. Peaks in glucose respiration suggested the presence of zinc-tolerant heterotrophs transiently capable of increased respiration of glucose but not glutamate. Concurrently, minimal but measurable biomass inferred the persistence of zinc-tolerant microorganisms in zinc-dosed epilithon. By the end of the studies, results indicated that metal-tolerant populations replaced metal-sensitive organisms under conditions of elevated zinc concentration. These zinc adapted communities had lower potential value as a food source to grazers (low protein: carbohydrate ratio) and were no longer distinctive with respect to glucose respiration.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00005725
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