Soaking up clues from freshwater sponges
University of Minnesota Crookston researchers, aided by students, are shedding light on freshwater sponges in Minnesota, which may be indicators of water quality.
Freshwater sponges have been filtering the waters of the northland for millennia. For the most part, their presence has escaped any attention, much less serious scientific scrutiny, but researchers at the University of Minnesota Crookston are in the process of changing that.
Since 2016, four faculty members—Karl Anderson, Anthony Schroeder, Venuopgal Mukku, and Timothy Dudley (two biologists and two chemists)—have been examining these non-moving invertebrates and what their presence might mean for Minnesota waters. And they've enlisted the assistance of students, including a grad student from the Twin Cities campus and undergraduates from Crookston, to aid in their research.
Their collective work could even lead to the discovery of new species of sponges. (Approximately 200 species have been identified worldwide, with 32 of those in North America.) But more important is the contribution the faculty and student scientists are making to the DNA sequencing of freshwater sponges. Their work will enhance the understanding of the sponges and their habitat, the role they play in the evolutionary cycle, and their role as a possible bio-indicator of a healthy ecosystem.
The last documented study of Minnesota freshwater sponges was in the summer of 1970, when a University of Minnesota graduate student collected sponge specimens in Itasca State Park near Bemidji. Today, scientists are capitalizing on 21st-century technology to generate more robust data.
Biologists Anderson and Schroeder collect the specimens for labeling and documenting and conduct immediate testing on site. Once they have a specimen and a sample from its water, they record location, pH, temperature, dissolved oxygen, and conductivity readings.
Back at the lab, the samples are separated—some for storage and archiving and some for genetic analysis using molecular biology and other research techniques. Chemical residue is studied by chemists Mukku and Dudley. They test to see if chemicals filtered by the sponge are absorbed in its cells, since this could enable those chemicals to move up the food chain. The chemical analysis will help determine if there are hazardous organic compounds harbored by the sponges.
Earlier research suggests that freshwater sponges tend to locate in pristine waters; therefore, they may serve as indicators of the quality of water in the lakes and rivers they inhabit.
The researchers plan to investigate freshwater sponge species in each of the 10 major watersheds in Minnesota. They'll collect sponges from two lakes or rivers in each watershed, identify the sponges, and map their distribution across the state.
The goal, Schroeder says, is to eventually integrate sponge research into the curricula for students in selected science courses at Crookston. The work has already involved students in other areas of science, as well as communication, making the research an interdisciplinary effort.