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An assessment of plankton populations, toxic cyanobacteria, and potential impact of introduced marine alewife (Alosa pseudoharengus) in Pawtuckaway Lake, New Hampshire
| Content Provider | Semantic Scholar |
|---|---|
| Author | Trout-Haney, Jessica V. |
| Copyright Year | 2006 |
| Abstract | Afield study was conducted during the summer, 2005 to evaluate the lake water quality and planktonic communities in Pawtuckaway Lake, NH. Of special concern was the condition of the plankton populations since the lake had been subjected to introductions of adult sea-run alewife. Overall water quality ranged from mesotrophic to eutrophic based on total phosphorus (8-31 !g L -1 ), chlorophyll a (max South, 5.0 !g L -1 ) and Secchi disk transparency (max North 5.1 m, min South 2.8 m). Of the three sites sampled, Fundy, North and South, Fundy (Z max < 2 m) did not stratify and had the highest concentrations of total phosphorus, followed by North and South sites, respectively. North and South sites stratified throughout the summer and developed anoxic hypolimnia, with the most severe oxygen deficit at the North site. Potentially toxigenic cyanobacteria were detected at all three sites. Throughout the summer, the concentrations of the cyanotoxin microcystin in the lake were well above the average for NH lakes. Lakewater concentrations of microcystins exceeded WHO drinking water standards (1000 ng L -1 ) at the North site (1204.0 ng L -1 ) on July 21. The two dominant cyanobacteria were Anabaenaspp.. and Microcystis aeruginosa. Oscillatoria(Planktothrix) were also present, but only rarely and therefore were probably were not responsible for most of the microcystins present in the lakewater. Mean zooplankton body lengths were significantly (p < 0.05) smaller at Fundy than South and North sites (Fundy 0.56 ± 0.052 mm SE, North 0.79 ± 0.031 mm SE, South 0.83 ± 0.043 mm SE). Grazing rates of the zooplankton were generally less than 20 % day -1 . Maximum zooplankton grazing occurred at Fundy in late summer and correlated with a chlorophyll aminimum, suggesting zooplankton may at times control the phytoplankton abundance in Pawtuckaway Lake. The small body size of the zooplankton at the Fundy site in July indicates an overabundance of planktivorous fish in this region of the lake. Such excessive predation on the grazing zooplankton can cause a “bottleneck” in the flow of energy through the lake food web resulting in a build up of undesirable phytoplankton, potentially leading to harmful algal blooms. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.cfb.unh.edu/PDF/2006/UNHCFBR_8_1_2006_Trout-Haney.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
