Spiders!

The following post is one of a series previewing the research that will be presented at the SETAC North America 41st Annual Meeting (SciCon2), 15–19 November 2020.

A guest post by Gale Beaubien

One day, my oldest daughter (age 5) had to poop, an event that typically requires the audience of my youngest (age 3). However, on this particular journey, my oldest saw a small cellar spider in the adjacent bathtub, and this sight caused both to scream bloody murder.

Now, I study riparian spiders (more on that later) and my daughters have lived most of their lives with a striped-knee tarantula, that they named “Mr. Mommy.” They talk to Mr. Mommy, they help me feed her, they tap the glass – by all accounts, they seem to like Mr. Mommy. Additionally, they’ve both seen me shuttle wolf spiders from inside the house to the outdoors. We look at spiders on my phone and we talk about how jumping spiders are cute (seriously, if you didn’t know this… look at pictures of jumping spiders. Jumping spiders have a pair of large front eyes that make them adorable). However, I guess they forgot.

An adorable jumping spider. Photo by Opoterser–own work, CC-BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5066311

That bathroom situation still puzzles me to this day. I mean, I’m not ashamed that my daughters require each other’s company when it’s time to poop, and I do wish they could have found comfort in each other’s arms instead of ugly crying over a spider very literally 1/100th the mass of their Mr. Mommy. But the real issue is that I truly thought I raised them to not fear these animals, so hopefully you can understand the calamity of that day was about as unsatisfying as Daenerys Targaryen’s story arc…and for that reason, I still think about the natural fear of spiders a lot and its limits.

I want you to know if you have this natural fear of spiders, it’s okay. Eight legs and eight eyes are inherently unnerving. But I also want to warn you that you may have been missing out. Riparian spiders are being developed by the U.S. Environmental Protection Agency’s office of research and development as an indicator of remediation effectiveness. But you should note, the use of riparian spiders in contaminant studies isn’t fascinating in a remediation effectiveness context – it is fascinating in every context.

One of the reasons riparian spiders are so fascinating is because of the journey aquatic contaminants must take to get into their tissues – via aquatic insects. Many aquatic insects have a complex life cycle where they go through metamorphosis and then become terrestrial flying adult insects (common examples are mosquitoes and dragonflies). During the aquatic stage of their life cycle, if exposed to bioaccumulative contaminants, like Methylmercury and polychlorinated biphenyls, the contaminants build up in the larval aquatic insect’s tissue. As the insect leaves, it carries the contaminant like luggage, as it moves to its new terrestrial home. Once in the terrestrial ecosystem, the insects can be captured and eaten by riparian spiders that spin a web directly above the land-water interface.

One of the riparian spider species used in the research (Tetragnatha elongata). Photo by Judy Gallagher, CC-BY 2.0: https://www.flickr.com/photos/52450054@N04/7436829424/

These spiders have shown great utility because they have a small home range (generally understood to be a few meters), and therefore can provide targeted information about contaminants in a small geographic area with more accuracy than predators with a wider range, such as fish. However, because these spiders serve as an additional opportunity for contaminants to biomagnify, the spiders may expose other arachnivorous predators, like passerine birds, to these contaminants. At the SETAC North America 41st annual meeting, SCICON2, I will present “The Spider Exposure Pathway and the Potential Risk to Arachnivorous Birds” (recently published in Environmental Toxicology and Chemistry). In this talk, I will not describe my personal philosophy on why people are scared of spiders or why “not all errands require a companion.” Instead I will describe the utility of riparian spiders in identifying contaminants of potential concern across two study areas. I will further describe how riparian spiders can be collected and then compared to calculated chronic and acute Arsenic, Cadmium, Copper, Nickle, Selenium, Zinc, and Methylmercury spider-based avian wildlife values for adult and nestling birds. The methodology presented here is flexible and can be applied in any initial site investigation to any bird species, in any part of the world, for any contaminant, as long as the requisite life history data and toxicological data are available.

Presentation information for SciCon2:

2.02.03: The Spider Exposure Pathway and the Potential Risk to Arachnivorous Birds

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