Devereux Slough

On our sixth field trip we visited Devereux slough and environs. After pausing to check out the middens along the side of the road leading down to the slough, we listened to the mockingbirds – always a treat. I hope now that you recognize their vocalization patterns you’ll notice them singing throughout your day…..and maybe even your night!
You can read more about the Northern Mockingbird at this site from Cornell U., as well as any birding field guide.

I found several lovely poems and haiku inspired specifically by this vocal arteest. A couple to share here:

This one from mon@rch nature blog

Mockingbird at night
would disturb the universe
and sing forever

And this one from a wonderful site called tinywords.com (“fresh haiku, delivered daily”)

first night of summer ...neither the mockingbird
nor I can sleep

copyright 2000.06.23 by gK

Perhaps you’ll be inspired to write your own nature haiku…

Ok, back to biology. The Devereux Slough is part of UCSB’s Coal Oil Point Reserve – another gem in the UC Natural Reserve System, described in a previous post. In the heart of the reserve, Devereux Slough is a seasonally flooded tidal lagoon that dries out in the summer to form salt flats and hypersaline ponds and channels.

We talked about estuaries (where a river meets the sea); a slough is a type of estuary formed at the outlet of a stream and other freshwater inputs to the ocean, and as a seasonally flooded lagoon, it is influenced by both tidal/sea and freshwater inputs.

Sloughs (and other estuaries such as bays & salt marshes) serve important ecological functions including: acting as nurseries for juvenile marine and terrestrial species, protecting shorelines from flooding and erosion (remember New Orleans), improving run-off quality by filtering nitrate and pollutants out of water, providing habitat for rare species and foraging grounds for migratory birds. BIG JOB!!

Unfortunately many sloughs and other coastal wetlands, being flat and conveniently located, well at the coast, have been filled in and built on. The sites of our California airports are almost all former slough/coastal wetland. Here’s a bit of local history for you…(from reports posted on www.countyofsb.org)

“The Goleta and Devereux Sloughs
The Goleta and Devereux sloughs were once part of a single large lagoon that sent arms of seawater as far north as Hollister Avenue almost to Lake Los Carneros. In the winter of 1861/62 a catastrophic storm filled the once navigable Goleta Slough changing it from a deepwater bay to a salt flat estuary by depositing as much as 10 to 14 feet of sediment. While the slough may eventually have returned to a deepwater bay, human intervention sealed its fate. A whale oil refinery was built there in 1879 and increased agricultural operations and related community development in the Goleta Valley fragmented and disturbed fresh water sources. Through the late 1890s and early 1900s, Mescaltitlan Island, once at the center of the slough, was used as fill for the railroad, the US Marine Base and what is now the Santa Barbara Airport. The island was gone by 1942. Still, in the 1930s the slough complexes covered about 1000 acres; today they are less than 350 acres.”
Lit cited: Tompkins, Walter. 1976. Goleta: The Good Land. Pioneer Publishing: Fresno, Ca.
This USGS map from 1903 shows the extent of the Goleta and Devereux sloughs at the time, and you can see the location of Mescalitan Island.

Walking along the edge of the slough we saw the plant that occupies the most area at the interface of water and land – pickleweed, Salicornia virginica. Though it’s not particularly tolerant of complete inundation it does have a wide tolerance for salinity levels from low salinity to extremely high, making it well suited for this zone in the marsh. Pickleweed is a halophyte, meaning that it can survive and grow in highly saline environments. I mentioned that salt in high concentrations is highly toxic to a plant, so how does pickleweed do it?

Plant that live in saline environments must have some kind of mechanism that allows it to filter out or excrete the salt from the leaves or remove it from the cells. In pickleweed some salt is filtered out at the roots by tiny sodium-potassium pumps within the cell membrane. However, there’s still a lot of salt that “leaks” into the plant. So, pickleweed has pumps within each cell that move the salt into vacuoles where it is stored. The green tissue of the plant has many large cells holding massive amounts of salt in interior vacuoles. That’s why, if you were curious (brave? crazy?) enough to taste this plant you’d have found it to be very salty, like pickles. That's how the plant got the name pickleweed. A bit further “upslope” from the pickleweed we saw one of the other salt marsh dominants, Alkali heath (Frankenia salina), and then California saltbush (Atriplex californica). Both of these species can tolerate some salt. We saw that they were both a bit “frosty” looking from the salt on their surfaces. Similar to other salt marsh species, like salt grass, they have glands which take the excess salt and secrete it out of the cells to the surface of the leaf. Read chapter 3, "Salt Marsh" in "An Island Called California" for a nice description of this habitat.

Thanks to Jordan’s reminder, we stopped to admire the work of the spittlebugs, spittling away on the coyote bush. Froghoppers (adult form) AKA spittlebugs (larval form) are in the family Cercopidae. There are some nice info sites on the web on these guys. Here are two:








spittle


At the freshwater pond – often overlooked by visitors to the slough – we saw very different plants and animals. No halophytes, but instead lots of tule (Scirpus californicus), which provides important habitat structure for all sorts of birds, including the red-winged blackbirds we saw there. (Our book - "An Island Called California" has a great chapter, entitled, "Red-Winged Blackbird" that you should read.) Tule also was important to the native Americans, as a source for making homes, baskets, and mats. You can learn how to weave your own tule mat to sleep on if you’d like.


One more thing I wanted to post information about – the beautiful metallic green beetles we saw on some of the coyote bushes was, the appropriately named, Coyote bush beetle (Trirhabda luteocincta). This species is a Chrysomelid, or leaf beetle. From the COPR insect sheet: “As their common name suggests, leaf beetles eat plants. Most are colorful, conspicuous beetles, frequently restricted in their feeding to one or a few similar plant species.… Trirhabda luteucinete, is abundant in the spring time and can be seen, as adult or larvae, on coyote brush, its host plant.”