A Natural History of Millbrook Marsh,
A Wetland In An Urbanizing Setting
The preceding lists of Millbrook Marsh fauna are by no means exhaustive with the exception of the benthic macroinvertebrates and fish. There are undoubtedly numerous species of amphibians and reptiles, as well as more small and medium mammals which inhabit the wetland and surrounding uplands. Additional formal inventories of the wildlife of Millbrook Marsh should result in a more comprehensive list of the species living in, breeding in, and migrating through the wetland. Obtaining formal baseline data is imperative in tracking trends through time, to recognize changes in the communities of the marsh.
Stormwater seems to be the limiting factor for benthic macroinvertebrates, which could in turn be limiting other vertebrate species. If the stormwater quality improves, or the quantity decreases, it is feasible that other species of vertebrates and invertebrates might return when the environment is healthier, especially considering the wide variety of habitat types in Millbrook Marsh.
Thompson Run definitely supported native brook trout, as did many other cold water streams in the past. The loss of brook trout from the site since 1941 is unfortunate, but not unexpected. According to long-time fly fisherman George Harvey (pers. comm. to R. Brooks), the Spring Creek drainage was dominated by brook trout in the late 1920’s. Brown trout have gradually replaced them as the dominant trout species. Loss of brook trout can be explained by either competition with brown trout or by declining habitat quality in the Millbrook streams. It is possible that a population could be reestablished and supported because of the cool water temperatures due to Bathgate and Thompson Spring’s groundwater input. For this to succeed, the immigrant brown trout would have to be removed periodically (Brooks et al. 1998).
On to Chapter 7