Aulacoseira nygaardii

This taxon appears to be limited to northeastern and Upper Midwest North America, and rather rarely reported from modern samples. In North America, this taxon has been reported from Michigan, Wisconsin, and Minnesota (Camburn and Kingston 1986), the northeastern US (Camburn and Kingston 1986, Camburn and Charles 2000), Quebec, Labrador (Fallu et al. 2000), and Cape Cod (Siver et al. 2005, Siver and Hamilton 2005). In the original description (Camburn and Kingston 1986), populations are also reported from Florida and Georgia; however, Siver and Hamilton (2005) report a similar taxon from that locality that was not of the type based on SEM analysis and recommended an SEM analysis of populations reported from southeastern states. Siver and Hamilton (2005) noted that the specimens presented in Florin (1981) in figs 47-49 may represent a population of A. nygaardii, which would expand the documented range to include northern Europe.

In the Great Lakes National Parks (Edlund et al. 2011, 2012, 2013), it is rare (1-2% relative abundance) in sediment core material from lakes in Voyageurs (Ryan and Ek lakes) and at St. Croix National Scenic Riverway (Lake St. Croix) (Edlund et al. 2009).

This taxon is reported to prefer weakly acidic, nutrient-poor habitats (Siver et al. 2005, Siver and Hamilton 2005) and appears to be sensitive to anthropogenic disturbance (Manoylov et al. 2009).

Several research groups consider this taxon an indicator organism and published regional environmental optima and tolerances including:

Camburn and Charles (2000): Abundance Weighted Mean (AWM) pH – 6.05 +/- 0.85, AWM Acid Neutralizing Capacity – 38 +/- 63 µeq/L, AWM total Al – 142 +/- 157 µg/L, AWM Dissolved Organic Carbon (DOC) – 301 +/- 149 µmol/L, AWM Total Phosphorus (TP) – 5.95 +/- 4.00 µg/L for populations from low alkalinity lakes in Northeastern US.

Fallu et al. (2000): DOC 14.11 +/- 1.26 mg/L for populations from Quebec. Color – 17 +/- 1.4 Pt units, Alkalinity – 31 +/- 1.8 µeq/L for populations from Labrador.

Siver and Hamilton (2005): report the populations they investigated from Cape Cod to occur in waters with pH ranging from 4.9-6.9.