Responses of periphyton to artificial nutrient enrichment in freshwater kettle ponds of Cape Cod National Seashore

Abstract

Nutrient enrichment bioassays, in conjunction with sampling and analysis of surface water chemistry, were conducted in freshwater lakes (kettle ponds) of Cape Cod National Seashore (Massachusetts, USA) to ascertain the importance of nitrogen (N) and phosphorus (P) in regulating the growth of periphyton. Arrays of nutrient diffusing substrata (NDS) were suspended 0.5 m below the water surface in a total of 12 ponds in July and August 2005. Algal biomass developing on each NDS after $3 weeks of exposure in each month was assessed by quantifying chlorophyll a + phaeophyton pigments. In both July and August, strong responses to N+P and N enrichments were observed in the majority of ponds, while P had no stimulatory effect. These responses correspond well with low atomic ratios (1-18) of dissolved inorganic nitrogen (DIN) to total phosphorus (TP) in ambient surface waters. The results suggest that conditions in the kettle ponds develop whereby nitrogen is the primary limiting nutrient to periphyton growth. While this may be a seasonal phenomenon, it has implications for nutrient management in individual ponds and within the larger watershed.

Nitrogen-stimulated growth of algae in surface-water samples collected from freshwater kettle ponds of Cape Cod National Seashore (Massachusetts, USA)

“…The locations and detailed descriptions of these ponds are provided in Portnoy et al (2001) and Smith and Lee (2006). The ponds are between 1 and 44 ha in size ( Figure 1) with maximum pond depth between 4 and 19 m (Portnoy et al 2001 soft (conductivity < 160 mS cm À1 ) with Secchi depths ranging between 3.5 and 16 m (Portnoy et al 2001).…”

“…Dissolved inorganic N (DIN):TP ratios, which provide a good indication of N versus P limitation (Smith and Lee 2006) were calculated from the water chemistry samples. For the bioassays, chl a data were log-transformed to improve normality and heteroscedasticity and subjected to one-way ANOVA ( ¼ 0.05) to verify whether any significant differences among treatment means existed within each pond and for each month (Statistica TM ver.…”

“…However, Smith and Lee (2006) demonstrated that nitrogen (N) rather than P stimulated the growth of epiphytic algae (periphyton) in freshwater lakes (kettle ponds) of Cape Cod National Seashore (CCNS). More recently, Kniffi et al (2009) found strong co-limitation of N and P for both periphyton and phytoplankton in coastal plain ponds in western Cape Cod.…”

Periphyton responses to nitrogen and phosphorus enrichment of shallow lake systems dominated by submerged plants: A mesocosm study

“…Enrichment with nitrogen (N) (Havens et al, 1999;Smith and Lee, 2006), and phosphorus (P) (Cattaneo, 1987;Vadeboncoeur and Lodge, 2000) is known to stimulate periphyton production. Excessive periphyton growth associated with elevated levels of both N and P has been also reported (Biggs, 2000;Dodds, 2003).…”

“…Interactions between nutrients, macrophytes and periphyton are complex (Phillips et al, 1978;Sand-Jensen and Borum, 1991), and relatively few studies have examined periphyton responses to N and P enrichment both individually and in combination in shallow lakes dominated by submerged plants (Liboriussen and Jeppesen, 2006;Smith and Lee, 2006). In this study, mesocosms dominated by Vallisneria natans (Lour.)…”