The Health of a Creek—Part Two
by Beth Lawton
Maryland Master Naturalist
In the midst of a deep cold snap, I am easily distracted by thinking of our property in warmer weather—so here is my second entry about our summertime experience with stream health testing. Readers may remember from part one of this blog post that our property has the good fortune of backing onto Watts Creek, a brackish estuary that feeds into the Choptank River and, eventually, on out to the Chesapeake Bay. We are part of the Maryland Biological Stream Survey (MBSS) program through the Maryland Department of the Environment, which gathers information for ensuring the protection and restoration of Maryland’s stream resources.
In this entry, I will report on the second series of tests, done in midsummer, that focused on fish in the creek. The results of these surveys, along with water quality and stream habitat measurements, are used to measure the overall quality and health of the stream.
The MBSS was created in 1993 by the Maryland Department of Natural Resources (DNR) as a way to characterize the health of Maryland’s 10,000-plus miles of freshwater streams. Data on the physical, chemical, and biological (fish and insects) characteristics are collected at each site and then combined into an overall assessment.
After one postponement due to rainy weather, a crew arrived at 9 a.m. on Thursday, June 15, 2017 in two large vehicles and proceeded to unload mountains of equipment onto our side yard.
The field biologists and research assistants for this visit included Nick Kaltenbach, Charlie Poukish, Tim Fox, Becky Monahan, Henry Ulrich, and Patricia Brady. These folks surveyed 22 streams, including ours, over the course of the summer, each of which required scheduling, travel, collection, and analysis of the samples brought back to the lab. Everyone in the group donned hip waders, grabbed some gear, and headed down to the same 75-meter section of creek where they did the insect study in March.
This time, they split into two groups and stretched fine-mesh block nets across the stream from bank to bank. Pegging them tightly with sticks and covering the bottom section with rocks, they were able to ensure that nothing could get in or out of that section without being counted!
Three members of the group then outfitted themselves with backpack electrofishers that discharge direct pulsed current. When the button on the probe (anode) is pushed, an electrical circuit is completed through the water when the current flows from the negative cathode (rattail) through the water and then to the positively charged anode (probe). This will stun fish and other animals that are in the immediate vicinity of the equipment. The rest of us, armed with fishing nets, followed closely behind to capture the stunned creatures.
The idea was to walk slowly the length of the netted-off section, stunning and collecting everything that we could find. The group as a whole would make two full passes, enough to be valid for both diversity and abundance. On each pass, the fish taken were put into holding buckets and in-stream live wells (a fancy term for plastic totes with waterflow holes in them) so they could be inventoried and weighed. The electrofishing equipment uses a voltage of 250–300, which stuns the fish (so we could capture and record them) but results in low mortality.
This picture shows the portable scale that we used. Some of the animals, especially the eels, did not stay “stunned” for long, so we had many hands to help move them from bucket to net to scale and then back to the creek.
Inside the Bucket
I was most impressed by the variety of fish that we found and by the size of some of the eels—I had no idea there were ANY eels in the creek, much less a dozen or so located in the 75-meter section we were sampling! And then there were the lampreys—who knew?! Even the smallest of these had the characteristic funnel-like sucking mouthparts. The eels were mostly discovered when the electrofishing paddles were held close to the shore, near where the shore was undercut by the creek’s flow.
The fish were released and quickly swam away . . . the electrofishing equipment did stun a few frogs, which we did not collect, but they too recovered very quickly. The larger eels were only barely stunned—and were often recovering before they could easily be handled for weighing and recording. On one occasion, it took three field biologists to wrangle one 20-inch eel back into the bucket!
What We Found
This list is from my field notes taken that day. For the fish that had tentative IDs in the field, the biologists took them back to the lab for more identification work.
The last part of the study focused on measuring and recording water quality, width of the stream, flow rate, and habitat (e.g., shade, sun, undercut banks, root wads, woody debris). More equipment came out, and the velocity of the waterflow was measured 4 feet from shore (.42 feet/second), 6 feet from shore (.50 feet/second), and 7 feet from shore (.55 feet/second).
Some additional correspondence with Nick Kaltenbach served as follow-up to our day’s outing. I had asked him about which fish species are more sensitive to disturbance, and here’s his response:
“DNR categorizes species as tolerant or intolerant to anthropogenic disturbance and stress. Three of the species we collected are identified as intolerant: the spotfin shiner, the fallfish and the margined madtom. We had quite a few of the spotfin shiners, so that’s a good sign. Four of the species we collected are identified as tolerant to anthropogenic stress: the tesselated darter, the green sunfish, the Eastern mudminnow and the redfin pickerel. Usually, a highly disturbed stream would be dominated by tolerant species with low overall species diversity and few if any Intolerant species. Watts Creek seems to have very good ecological health, but we’ll see what the IBI score will be when the data is calculated. The other species collected are not categorized as either tolerant or intolerant.”
The two-day creek study is part of an ongoing study of Maryland streams deemed to be in good shape. Watts Creek was last studied approximately five years ago. About a month after the fish survey, I heard from Nick Kaltenbach again—reporting his estimated Fish Index of Biotic Integrity (FIBI) score of 3.67 for our section of Watts Creek—this measurement is used to determine the state’s “high quality waters” (Identified as Tier II waters) and helps identify watersheds that can or cannot assimilate more development. The FIBI contains twelve metrics that relate to species richness, balance, and the proportion of individuals belonging to specific feeding and habitat groups.
Nick’s draft report also gave us some totals:
- Total weight or biomass of all fish was 2,879 grams.
- This site had a total of 325 total fish and 14 species.
- Water temperature was 21.28o C (70.3o F)
- pH was 7.17
- Conductivity was 152 uS
- Dissolved oxygen was 7.90 mgL -1 with 89% saturation
- Flow at the time of sampling was 2.56 cfs (cubic feet per second)
The biologists were all impressed by the undisturbed nature of the creek and its immediate environs—the fact that there was an “undisturbed forested riparian buffer” contributes to stream health, not the least by adequate tree canopy cover shading the creek from direct sunlight.
We are committed to helping keep this stream healthy in whatever ways we can—and we are so pleased that Maryland is continuing to monitor the health of the waterways, especially in these watersheds that are so near to agricultural and residential areas.
by Beth Lawton