Geology topics

Leonard C. Ferrington

Publications and source records attributed to Leonard C. Ferrington.

4 recordsLinked to original sources

USGS2015

Survivorship and longevity of adult Diamesa mendotae Muttkowski, 1915 (Diptera: Chironomidae) at controlled, sub-freezing temperatures

Diamesa mendotae Muttkowski, 1915 is a winter-active species common in groundwater-buffered streams of Minnesota and Wisconsin. This species is capable of surviving under snow cover for at least 28 days. Field collections of adult D. mendotae were used to determine survivorship under long-term exposure to controlled sub-freezing conditions. Specimens were placed into a controlled temperature chamber at −5 °C, batches removed at weekly intervals, and subsequently held at 6 °C to determine survivorship and longevity. Our results indicate that overall survivorship is negatively related to treatment duration of sub-freezing treatment, individuals can survive sub-freezing temperatures for at least 70 days, with total longevity of 92 days. Additionally, males had a significantly higher rate of survivorship than females within treatments. Total longevity increased with treatment time, suggesting adult D. mendotae may survive long periods of below-freezing temperatures under natural conditions before mating, which may convey population-level advantages.

Aquatic Insects↗

USGS2015

Reach-scale stream restoration in agricultural streams of southern Minnesota alters structural and functional responses of macroinvertebrates

Recent studies suggest that stream restoration at the reach scale may not increase stream biodiversity, raising concerns about the utility of this conservation practice. We examined whether reach-scale restoration in disturbed agricultural streams was associated with changes in macroinvertebrate community structure (total macroinvertebrate taxon richness, total macroinvertebrate density, Ephemeroptera, Plecoptera, Trichoptera [EPT] taxon richness, % abundance of EPT taxa) or secondary production (macroinvertebrate biomass over time). We collected macroinvertebrate samples over the course of 1 y from restored and unrestored reaches of 3 streams in southern Minnesota and used generalized least-square (GLS) models to assess whether measures of community structure were related to reach type, stream site, or sampling month. After accounting for effects of stream site and time, we found no significant difference in total taxon richness or % abundance of EPT taxa between restored and unrestored reaches. However, the number of EPT taxa and macroinvertebrate density were significantly higher in restored than in unrestored reaches. We compared secondary production estimates among study reaches based on 95 th -percentile confidence intervals generated via bootstrapping. In each study stream, secondary production was significantly (2–3×) higher in the restored than in the unrestored reach. Higher productivity in the restored reaches was largely a result of the disproportionate success of a few dominant, tolerant taxa. Our findings suggest that reach-scale restoration may have ecological effects that are not detected by measures of total taxon richness alone.

Freshwater Science↗

USGS2013

Winter feeding, growth and condition of brown trout Salmo trutta in a groundwater-dominated stream

Winter can be a stressful period for stream-dwelling salmonid populations, often resulting in reduced growth and survival. Stream water temperatures have been identified as a primary mechanism driving reductions in fitness during winter. However, groundwater inputs can moderate water temperature and may reduce winter severity. Additionally, seasonal reductions in prey availability may contribute to decreased growth and survival, although few studies have examined food webs supporting salmonids under winter conditions. This study employed diet, stable isotope, and mark-recapture techniques to examine winter (November through March) feeding, growth, and condition of brown trout Salmo trutta in a groundwater-dominated stream (Badger Creek, Minnesota, USA). Growth was greater for fish ≤ 150 mm (mean = 4.1 mg g −1 day −1 ) than for those 151–276 mm (mean = 1.0 mg g −1 day −1 ) during the winter season. Overall condition from early winter to late winter did not vary for fish ≤150 mm (mean relative weight (Wr) = 89.5) and increased for those 151–276 mm (mean Wr = 85.8 early and 89.4 late). Although composition varied both temporally and by individual, brown trout diets were dominated by aquatic invertebrates, primarily Amphipods, Dipterans, and Trichopterans. Stable isotope analysis supported the observations of the dominant prey taxa in stomach contents and indicated the winter food web was supported by a combination of allochthonous inputs and aquatic macrophytes. Brown trout in Badger Creek likely benefited from the thermal regime and increased prey abundance present in this groundwater-dominated stream during winter.

Minnesota↗

USGS2013

Air - water temperature relationships in the trout streams of southeastern Minnesota’s carbonate - sandstone landscape

Carbonate-sandstone geology in southeastern Minnesota creates a heterogeneous landscape of springs, seeps, and sinkholes that supply groundwater into streams. Air temperatures are effective predictors of water temperature in surface-water dominated streams. However, no published work investigates the relationship between air and water temperatures in groundwater-fed streams (GWFS) across watersheds. We used simple linear regressions to examine weekly air-water temperature relationships for 40 GWFS in southeastern Minnesota. A 40-stream, composite linear regression model has a slope of 0.38, an intercept of 6.63, and R 2 of 0.83. The regression models for GWFS have lower slopes and higher intercepts in comparison to surface-water dominated streams. Regression models for streams with high R 2 values offer promise for use as predictive tools for future climate conditions. Climate change is expected to alter the thermal regime of groundwater-fed systems, but will do so at a slower rate than surface-water dominated systems. A regression model of intercept vs . slope can be used to identify streams for which water temperatures are more meteorologically than groundwater controlled, and thus more vulnerable to climate change. Such relationships can be used to guide restoration vs . management strategies to protect trout streams.

Minnesota↗