Species Sampling: Crayfish

In late January, with temperatures hovering in the low 30s, a team of GSC staffers took to the streams to identify crayfish. Why, you might ask, would you wait for such a cold day for this particular project? We, the marketing department, had the same question as we were unceremoniously dragged from our heated office spaces to document the activity. According to our fearless leaders, Lindsey Zarecky, the GSC’s VP of Conservation and Research, and Brena Jones, of the North Carolina Wildlife Resources Commission, digging up crayfish is actually one area of research that lends itself to a winter excursion. The lack of new growth present at this time of year makes it easier to spot crayfish burrows and holes in the streambed.

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We know what you’re thinking… crayfish aren’t all that exciting. We thought so, too, initially. But read on! We’re going to share some truly fascinating factoids about a species present in our own backyards.

The first step to identifying crayfish, we learned, is locating them. Crayfish are burrowers. They are categorized based upon their habitat preference as primary burrowers (meaning they spend most of their time in burrows), secondary burrowers (meaning they are more often found in streams than burrows), or tertiary burrowers (meaning they are only found in burrows during breeding season). In order to find the animals, our team walked slowly through the stream, lifting rocks and looking for movement and searching for raised mounds that could indicate the presence of a burrow.

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Once the crayfish were found, the real fun began. Each animal was first identified by looking for several characteristics that distinguish one species from another. When it comes to pincher claws on a crayfish, size matters – for identification purposes, of course. The fat pinchers of the Cambarus are relatively obvious when compared with the long, narrow pincher claws of the Procambarus. Since crayfish can regenerate their claws, a tip Brena had for our team was to always look at the bigger claw for better accuracy.

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In addition to pincher claw size, the width between the lines on top of the animal’s carapace (or top shell), the presence or absence of spines on the carapace, and the pointiness or bluntness of the rostrum (which is a fancy word for the space between the eyes) can all be used for identification purposes. With that being said, there are a lot of undescribed species of crayfish in North Carolina, which can make identification challenging!

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Once the species was identified, some – ahem – personal information was also collected and recorded, such as the overall size and the sex. Males, Brena showed us, have an extra set of swimmerets, rigid in nature, on the underside of their tail. Each animal was also given a gentle squeeze. Pardon the scientific terminology here: a “squishy” crayfish may have recently molted. A shed exoskeleton means a growing crayfish!

Now, on to the big questions: why, exactly, are we digging up crayfish? Well, scientists, including the GSC’s own Lindsey Zarecky, are studying the effects of urbanization on wildlife. The recent sampling of species performed in our stream will establish a baseline for comparison as our facility continues to grow and expand. Knowing what the ecosystem looks like before, during and after construction will help scientists understand how to find a balance between continued development and maintaining native wildlife populations. The ultimate goal is to discover how to create a scenario where everyone wins – both humans and wildlife alike.

Pond & Stream Research: Now, During Construction and Post Construction

The Greensboro Science Center has partnered with UNC Greensboro for a long-term study to assess the overall water quality of the stream and pond located in the woods behind our current zoo. The study began in the spring of 2018. We’ll be taking monthly water quality measurements continuously until the zoo expansion is complete (projected to happen by 2020) as well as after the expansion opens. We are interested in learning how water quality changes during construction and also post-construction. Our goal is to improve the overall water quality of the pond and stream.

While we are working with UNCG on data collection, this project is not assigned to a particular student. Kristina Morales, a doctoral student at UNCG is currently pursuing her PhD in Dr. Tsz-Ki Tsui’s lab. Dr. Tsui studies the effect of mercury on the environment. Kristina’s work is focused on the mercury cycle at the wetlands installed on UNCG’s campus in 2017. Specifically, she is studying how restored wetlands impact methylmercury production. She has been assisting the GSC with our water quality testing as part of her research.

Today, Lindsey Zarecky, the GSC’s VP of Conservation and Research, and Kristina are sampling water quality, macro-invertebrates and metals like mercury in the GSC’s stream and pond. Samples are collected via a YSI probe, which is placed into the water to provide a reading of the water’s dissolved oxygen, temperature and conductivity, the latter of which is a measure of the water’s ability to carry an electrical current. For our purposes, conductivity informs us of the mineralization in the water. Minerals leach into the water from the erosion of rocks and as result of urban runoff.

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We also measure the dissolved oxygen (DO) or the amount of oxygen (O2) dissolved in the water. DO is necessary for a healthy waterway. For Kristina’s work, she looks at DO because low DO allows microbes to convert mercury into methylmercury, a water toxin. Lastly, we measure temperature because some negative ecosystem organisms do better in higher temperatures. Collectively, these measurements inform us of the water’s overall quality.

DSC_1453We are also interested in learning what lives in our pond, so we use a dip net to collect macroinvertebrates. On this particular day, the air temperature was around 92°F, so the water was quite warm. Because of the temperature, organisms were most likely deep in the cooler sediment, beyond our reach. We did collect one crayfish and two dragonfly larvae.

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As mentioned above, we will continue to take samples each month and track the data to watch for trends. We may see seasonal shifts and annual shifts as we start construction on our zoo expansion. We’re excited to learn more about ways we can improve the quality of the water in our stream and pond as we continue to grow!