Species of the Month

Halloween is right around the corner, so it’s time for another creepy crawly species of the month. We’ve covered bats and owls, so this year we’ll go to the spiders. Stop reading here if they creep you and come back next week. Grass spiders are a genus of several funnel weaving spiders, including the Pennsylvania grass spider. You’ll likely start noticing these robust spiders in your house as they venture inside to avoid the falling outdoor temperatures. We associate spiders with Halloween because they are at their biggest after growing all year.

Pennsylvania grass spider at my sister's house

Scientific name: Agelenopsis species

Kingdom: Animalia (animals)

Class: Arachnida (arachnids)

Order: Araneae (spiders)

Range: All of North America except Arctic areas

Habitat: Lawns, your house during fall

Grass spider in its natural habitat (Penn State)

Lifespan: One year

Diet: Insects

Predators: Birds

Conservation Status: No special protection

Grass spider in its web (Missouri Department of Conservation)

Other Information: Grass spiders build funnel or tunnel shaped webs in the grass, hence the name. Females lay eggs in sacs during late summer or early fall, with eggs hatching in spring. The eggs survive over the winter but adult spiders do not. Grass spiders are fast and typically avoid humans, but will occasionally bite with trapped and threatened. Information this week comes from Insect Identification, despite spiders not being an insect.

Symbiotic Fish and Forests

With the arrival of fall, salmon spawning is in full swing in the Pacific Northwest. Being a fish, they obviously interact with a lot of other sea creatures and aquatic life. They also have a symbiotic relationship with the forest, believe it or not.

Fish and forests, at first glance, are as different as, well, fish and forests. But despite being a water-based critter and chunk of land, they interact with each other splendidly. They feed each other. I’ll explain how, starting with the how the forest helps the salmon.

McClane Creek, an example of healthy salmon habitat

Forest trees are crucial to salmon habitat. Despite living in a river for part of their lives, salmon lean heavily on trees for survival. Salmon need cool, clean water. The forest keeps the river clean by slowing the flow of surface water and the sediments it carries. Sediments can clog their gills and cover the rocks where they lay their eggs during spawning. Shade from the trees keeps the water temperature at acceptable levels during the summer. Warmer water loses dissolved oxygen, and salmon are very picky about temperatures.

Pink salmon returning to the cool, shaded water of Nisqually River

Fallen trees in the river create habitat diversity. The large woody debris forces the current to change, creating deep pools on the downstream side of the obstruction and changing the complexity of the stream bed. The deep pools provide a place to hide from predators and respite from high flows during the rainy season. The large woody debris adds nutrients to the ecosystem as it decomposes. It also contains or attracts tasty insects for the salmon to munch on.

Artificial logjams like this are used as habitat enhancement
in salmon streams.

The salmon help replenish the forest by provided nutrients (nitrogen in particular) from the sea when they die. Predators are the immediate beneficiaries of the ocean’s bounty, but the forest as a whole benefits. Plenty of leftovers decompose both in the river and on land. As the fish decomposes, or after a bear poops in the woods, the trees and other plants absorb the nutrients so they can continue to give back to the salmon and the cycle continues for another season.

Salmon bones replenishing the Hoh Rainforest

It was once thought that removing obstacles like large woody debris was an improvement to the riparian habitat. Now we know better. In some areas, workers are dropping downed trees into rivers. In others, engineered logjams do just as well. Watch this short video about riparian restoration for the benefit of salmon and flood control in Oregon.

Superfund Site

While I was working toward my environmental science one of my classes was Environmental Law and Policy. For one of our assignments we had to research a Superfund site and present to the class. The site I chose was less than a mile as the crow flies from where I grew up. At that time, EPA hadn’t begun work on the site. Last year after moving back to Pennsylvania, I attended an EPA meeting on the status of the cleanup. This year, as work nears completion, I was able to tour the site with EPA’s Tim Gallagher.

Contrary to what you might think, not all Superfund sites are full of leaking drums of glowing green radioactive waste. The Watson-Johnson property was a landfill from the 50s to the 70s, then forgotten about. In the late 90s, water testing revealed several contaminants in the groundwater. One of the town wells for the water supply was closed. The solution the EPA came up with was to cap the landfill and use chemical injection to neutralize the contaminants in the groundwater.

Watson Johnson landfill site. The geosynthetic is
buried under 18 inches of soil here.

Capping the landfill is a common practice at sites like this. Why not remove the waste? Odds are, everything would just be taken out of the ground and buried in another landfill somewhere else. One oozing container was discovered and removed from the site, but otherwise it was all collected together and capped. The cap uses a layer of compacted clay soil, a waterproof synthetic fabric, more soil, and vegetation. The purpose of the cap is to keep the waste contained and keep water out, preventing anything from seeping into the groundwater.  Water drains to wetlands, ponds, and level spreaders. Level spreaders are cement cisterns that capture water and allow it to overflow and slowly spread away from the site.

Drainage swale around the outside of the capped landfill.
Grass seed has already been spread inside it.

Level spreader beyond the edge of the capped landfill

The soil above and around the cap is contoured to divert surface water away from the cap. There are natural wetlands on site, as well as new artificial wetlands created to contain and disperse runoff. The cap itself layered in a way that creates pathways for gases flow towards several vents. Because they site was once open but now is closed with those release points, concentrations are higher. Methane has been noted at the vents, but not volatile organic compounds (VOCs).

Gas vent. No monitors are attached.

Monitoring and injection wells reach the groundwater. Sodium permanganate is injected to react with the chemicals in the water. The reaction breaks down the chemicals (including the sodium permanganate) into harmless elements like oxygen and hydrogen. Monitoring wells are set up to test the levels of chemicals in the water. Injections will stop once the concentration goes below 100 parts per billion. At that point, EPA will begin bioremediation. Microscopic critters that eat the contaminants will be injected to the groundwater to bring the contaminants down even further.

Work on the site is nearing completion. Despite a cold winter and rainy summer, work is only two months behind schedule. Workers are currently adding a layer of topsoil six inches deep on top of the cover soil. Once topsoil is in place, it will be seeded with native grasses. Around the cap, workers are setting up deer fence to protect new trees that will be going in. Landscaping was supposed to start last week but was delayed by heavy rain.

EPA will continue to monitor the site for a year after completion, before turning that duty over to the state. Future plans include nesting boxes for swallows and bats. The new trees will create a nice matrix with the older existing woods on the edge of the site, which should attract songbirds that prefer new growth. The site is privately owned, so it will not become a park like old landfills in other areas. However, development will be limited by cap so it will likely remain a nice green oasis as the area becomes increasingly more urbanized.

For more information visit the EPA's Watson Johnson website. Special thanks to Tim Gallagher for taking time out of his day to show me around.

Firefly Watch

I participated in an ongoing citizen science project over the summer. Firefly Watch was formerly run by Boston’s Museum of Science, but was run by Massachusetts Audubon this summer, my first with the program. The goal is to monitor firefly populations by counting the number of flashes in three periods of ten seconds. Colors and flash patterns, as well as date, time, weather conditions, and site conditions are all recorded. I signed up for this because fireflies were always a highlight of the summer when I was a kid, and later when my own kid was little. 

Having been away from my ancestral home for a decade, I had no knowledge of local population trends other than my mom telling me she never sees fireflies anymore. That was disturbing to hear. So twice a week I went to my parents’ house starting in late May to see if they had any fireflies left. The first ones showed up on Memorial Day, right about when I remember them first arriving. They were few and far between for the first two weeks or so and peaked around the 4^th of July. I decided to keep up the watch until I had two consecutive shut outs, and expected to be done the first week of September. 

However, the last firefly I recorded was on September 24^th, later than I’ve ever seen one. In fact, I only remember seeing them in September once before, and they came a month late that year. To top it all off, I saw another on September 28^th during the day while away from home. However, to be consistent I only counted observations at one site. To me, it isn’t helpful to track population trends if I am not tracking at the same location, at least in this case. For something larger with a wider range I would, but these little guys don’t roam very far. Since this was my first field season I have no data to compare with, but I plan on being back. Hopefully all I’ll see is positive trends!

Feel free to sign up for Firefly Watch next year!