Original paper
Temporal and spatial dynamics of suspended sediment, nutrients, and algal biomass in Mark Twain Lake, Missouri
Knowlton, Matthew F.; Jones, John R.
Archiv für Hydrobiologie Volume 135 Number 2 (1995), p. 145 - 178
44 references
published: Dec 14, 1995
DOI: 10.1127/archiv-hydrobiol/135/1995/145
ArtNo. ESP141013502000, Price: 29.00 €
Abstract
Suspended sediment, nutrients and algal chlorophyll (CHL) were monitored over a 29 month period at 19 sites in Mark Twain Lake, a 7550 ha reservoir in northeastern Missouri. Sampling began during a record drought and continued through subsequent periods of average rainfall. Turbid inflows (≈1000 mg/L TSS) during flood events produced consistently high concentrations of suspended sediment (>200 mg/L) and nutrients (TP > 300 µg/L, TN > 2 mg/L) in headwater areas, but effects in the reservoir mainstem varied with thermal regime. Inflows during winter mixing affected the entire waterbody while inflows during stratified periods had little effect on surface strata in the mainstem. Loading of nutrients and sediment to the trophogenic zone thus depended less on quantity of inputs than their timing. The size range of suspended materials initially declined with increasing hydraulic residence time but subsequently increased as organic, presumably, autochthonous seston replaced allochthonous minerals as the dominant particle type. Algal blooms seemed to increase sedimentary loss of mineral seston from the epilimnion. Dynamics of phosphorus and suspended sediment were closely parallel and dominated by fluvial inputs. Dynamics of TN, organic N, nitrate and ammonia, however, seemed equally affected by external inputs and internal cycling and TN exhibited far less year to year variation than TSS or TP. CHL time series revealed numerous brief blooms with little temporal or spatial consistency. Phytoplankton may have become nutrient limited during blooms but were probably light limited except during clear water periods near the start and end of the study. On the basis of growth experiments and maximum area. CHL, algal biomass was probably light limited at irradiances < 2-5 e m-2 d-1, a range comprising 79 % of our observations. The strong relation between phosphorus and suspended material in Mark Twain Lake holds for other Missouri reservoirs and results in a dome-shaped CHL-TP relation in which phytoplankton are P-limited at low TP (low turbidity) and light limited at high TP (high turbidity). This trend is less evident among Iowa lakes and is probably region-specific.
Keywords
turbid inflows • waterbody • trophogenic • algal blooms • Mark Twain Lake • Missouri • USA