Microbial Community in Hyperalkaline Steel Slag-Fill Emulates Serpentinizing Springs

To date, a majority of studies of microbial life in hyperalkaline settings focus on environments that are also highly saline (haloalkaline). Haloalkaline conditions offer microbes abundant workarounds to maintain pH homeostasis, as salt ions can be exchanged for protons by dedicated antiporter proteins. Yet hyperalkaline freshwater systems also occur both naturally and anthropogenically, such as the slag fill aquifers around former Lake Calumet (Chicago, IL, USA). In this study, 16S rRNA gene sequences and metagenomic sequence libraries were collected to assess the taxonomic composition and functional potential of microbes present in these slag-polluted waterways. Relative 16S rRNA gene abundances in Calumet sediment and water samples describe community compositions not significantly divergent from those in nearby circumneutral conditions. Major differences in composition are mainly driven by Proteobacteria, primarily one sequence cluster closely related to Hydrogenophaga, which comprises up to 85% of 16S rRNA gene abundance in hyperalkaline surface sediments. Sequence identity indicates this novel species belongs to the recently established genus Serpentinomonas, a bacterial lineage associated with natural freshwater hyperalkaline serpentinizing springs.

Black-crowned Night-Heronsof the Lake Calumet Region,Chicago, Illinois

The number of active black-crowned night-heron (Nycticorax nycticorax) nesting colonies in Illinois has declined significantly over the past century. Habitat loss/degradation and other factors such as exposure to environmental contaminants and competition for nest sites at established colonies may have contributed to this decline. In this study, we examined recent trends in population levels of Black-crowned Night-Herons nesting at wetlands associated with Lake Calumet in southeastern Chicago, Illinois. The number of black-crowned night herons nesting annually at these wetlands has fluctuated widely over the last two decades. Immigration of herons from riverine colonies may have driven population increases during the mid-1980s and early 1990s. However, this population has remained relatively stable at between 300 and 400 pairs during 1997–2003.

Black-crowned Night-Herons of the Lake Calumet Region,Chicago, Illinois

We examined the nesting ecology of a Blackcrowned Night-Heron (Nycticorax nycticorax) colony located at wetlands associated with Lake Calumet in south Cook County, Illinois, during the 2002 and 2003 nesting seasons. This area of southeastern Chicago has been greatly impacted by heavy industry, solid and chemical waste disposal, urbanization, and altered hydrology. Black-crowned Night-Herons (BCNH) have nested at five known locations at Lake Calumet wetlands during 1984–2003. Emergent cover (giant reed, Phragmites australis) was of primary importance to this colony for nesting during that time. Cottonwoods (Populus deltoides) also were used for nesting from the late 1980s to mid-1990s. During 1993–2003 the herons began arriving at the colony as early as March 10. During the two years of this study the earliest indications of nest building and courtship occurred during the first week in April; the first pairs and precopulatory displays were observed during second week of April in both years. The egg-laying period extended from April 20 to June 12 in 2002, and from April 16 to May 27/28 in 2003. Hatching occurred from mid-May to the first few days of July in 2002, and from mid-May to June 19/20 in 2003. Juvenile dispersal in 2002 occurred from mid-July through late August, and from early July through mid-August in 2003. Reproductive parameters in BCNH nesting at the north end of Indian Ridge Marsh (IRM), the primary nesting location for this colony in both years, were typical for this species. In 2002 the “recruitment” rate (number of young/nest surviving to 15 days) of 1.74 young/pair was below the threshold of 2.0–2.1 young/nesting pair thought to be necessary to maintain BCNH populations. However, recruitment increased to 2.22 young/ pair in 2003, which was among the highest previously reported. The most important cause of nest failure was poorly constructed (flat) nests which allowed the eggs to roll out into the water. Although some eggs were lost to gulls and some hatched young were taken by unknown mammalian or avian predators, predation was not an important cause of nest losses at IRM.