Archives

All posts for the month December, 2008

By: Ginger North, Citizen Science Coordinator

Although most insects are not active in the winter in Delaware, there is one group that is happy when the weather turns cold. Aquatic insects love the winter because cold water holds more oxygen which they need to live. Aquatic insects (formally called benthic macroinvertebrates) are important indicators of water quality. In fact, Delaware has a State Macroinvertebrate, the stonefly!

 

Stonefly larvae Photo by Morenci students in Michigan

Stonefly larvae - Photo by Morenci students in Michigan

Stonefly larvae are very sensitive to low levels of oxygen and their presence is an indicator of excellent water quality. There are several types of stoneflies native to Delaware’s rivers and streams. One type is called the winter stonefly because it actually emerges as an adult on warm winter days. If you are out walking near a high quality stream in the winter, look for these small black insects on the river banks. They are easier to see if there is snow on the ground. 

Adult Winter Stonefly on snow

Adult Winter Stonefly on snow

 

 

You can see the larvae in the water at any time of the year, although fall and early spring are especially good times as the larvae are larger than in the late spring and early summer. If you are lucky enough to find these “stream critters”, it indicates that you are looking in a stream with excellent water quality.

Mayfly - Photo by Valley City State University staff

Mayfly - Photo by Valley City State University staff

 

Caddisfly Larvae

Caddisfly larvae

Cranefly larvae - Photo by Michael Clapp

Cranefly larvae - Photo by Michael Clapp

 So get outside and check out the leaves and rocks in the creek. There are lots of aquatic insects in Delaware’s streams, including caddisflies, mayflies, and craneflies to name a few. If you are really lucky you might be able to find the State Macroinvertebrate!  For information about adopting a local stream to evaluate, and future Stream Adoption Workshops, email me at ginger@delawarenaturesociety.org.

By: Sally O’Byrne, Teacher Naturalist

 

 

The Delaware Nature Society trip to the Veolia Wastewater Treatment Facility (Wilmington Wastewater Plant) on December 10 was not your usual natural history tour.  However, learning a little about what happens to our wastewater, from toilets to dishwashers to industry to stormwater is probably good for all us waste-producing citizens to know about. 

 

Water comes into the plant where it is strained, degritted, and clarified, using no chemicals in the process.  Most of the work breaking down the organics is done by microbes, otherwise known as ‘bugs’; all sorts of ‘bugs’ that contribute to different parts and chapters of the cleaning.  This gets a little complicated when the amount of waste water coming in changes every day, or every week, or every hour, and when accidental discharges of nasty things into the system disrupt the balance.

 

 

 

 The ‘bugs’ need oxygen, so there are pipes aerating the tanks of wastewater to help the process along.  Later in the process, the sludge goes into an anaerobic digester where the methane is collected to heat the ‘bugs’ so the process can start all over again.   Other than the microbial ‘bugs’ the other living organisms present were gulls – lots of them, and by far the most common was Delaware’s own Larus delawarensis – the Ring-billed Gull.

 

 

 

For the final or tertiary stage, the now mostly clean water is pumped up the hill to very large settling ponds where there is further aeration and a final dose of chlorine before it is discharged into the Delaware River.  These ponds are great places to find waterfowl in the winter, and today we saw many Northern Shovelers, Ruddy Ducks, Ring-necked Ducks, and American Coots.  However, they were distant to us, even with the aid of a spotting scope. 

           

The Wilmington Christmas Bird Count was yesterday and Jim White and I visited the same location, so stay tuned to see the report……….

 

 

by The Unknown Astronomer

I hope you all had unclouded views of the gorgeous conjunction of Venus, Jupiter, and the moon last weekend, and that you continue to observe Jupiter in decline and Venus ascendant.  Of course, the two planets are not really approaching and receding from one another in space.  What is actually going on is more a race than a dance.

Jupiter, Venus and Moon, Dec 1, 2008.  Image from Starry Night Pro Software

Jupiter, Venus and Moon, Dec 1, 2008. Image from Starry Night Pro Software

Picture a circular track with the sun in the center.  The innermost lane is occupied by the planet Mercury, whizzing around the track like Jimmie Johnson at Dover Downs, and completing its circuit in a mere 88 days.  Venus is in lane 2, making its journey in a zippy 243 days – not exactly NASCAR, but at least a turbo-charged Mustang.  Earth orbits in lane 3, getting once around in a respectable 365 days – the Mustang minus the turbocharger. By the time we get to lane 6, way out beyond Mars and the asteroids, it’s taking 12 years to complete one circuit.  That’s Jupiter – a Yugo driven by your grandmother.

So, what we have been observing over the last couple of weeks is a nightly snapshot of speedy Venus overtaking plodding Jupiter, from the perspective of lane 3.

Another effect of where we all are in space (or on that track) is the sometimes peculiar look of Venus through a telescope.  Right now it appears to be a tiny half-moon!  Indeed, like the moon, Venus (and Mercury) has phases, and for the same reason:  since it is inward toward the sun from our perspective on Earth (lane 2 as seen from lane 3), the planet will at times be only partially lit, appearing as full,  half, or crescent as it approaches and overtakes the Earth.

Now, how do you follow an act like a planetary conjunction?  WIth a meteor shower!  The Geminids, so named because they appear to radiate from the constellation Gemini, peak on the night/morning of Dec. 13 – 14.  These are bright, medium-fast meteors that can be colorful: In addition to the usual white, I have seen distinctly yellow and green ones, and they can also be blue or even red.  You can start looking a little north of east any time after 8:00 pm.  Gemini will have just cleared the horizon by then, so the best time to observe is realy after midnight, when Gemini is high in the sky.  There is one major problem with this year’s shower, however – we will be just one night removed from the largest, closest, brightest full moon of 2008, which will blot out all but the brightest meteors.  Ah, the moon – beloved of poets and romantics, bane of astronomers…

No matter which category you fit into, if it’s clear, brave the cold anyway – at it’s height,  this shower can produce a meteor a minute!

By John Harrod, Backyard Habitat Coordinator

 

Yesterday Delaware Nature Society staff went to the Wilmington Riverfront for our annual Christmas field trip to see two construction projects – one completed and one in progress.

 

Our first destination was at the Barclays building to see a green building technique – a newly installed green roof. On this cold, gray winter-like day, the landscape on the roof looked pretty desolate. It was reminiscent of the arctic tundra containing only inches-high sedum plants growing on a bed of gravel. Thought the plants are still filling in, I imagine what it would look in the summer with a lush carpet covering the roof with greens, yellows, and oranges. Even now in its duller winter shades it is still more beautiful than a traditional roof.

 

 

So why grow a bunch of plants on the roof of an office building…for lunch time respite maybe? While that is an added benefit, it was actually built to help alleviate storm water problems caused by rain water running across impervious surfaces like roofs and pavement instead of infiltrating (soaking) into the ground. When it rains, this roof collects and holds the water that would otherwise run off the roof and pick up pollutants, carrying them to the nearest stream or river…in this case, the Christina River.

 

After viewing the green roof we walked along the riverfront, viewing beds of native plants along the way including one of my favorites, the scarlet rose mallow (Hibiscus coccineus). Our destination was beyond the Shipyard Shops where the sidewalk ends. Located there is the Peterson Urban Wildlife Refuge and within it the soon to be completed DuPont Environment Education Center. DNS will operate the center once it is completed in 2009. The center will offer fantastic views of the marsh, river and city, as well as exhibits and activities year-round on a variety of urban environmental issues.  Look for future announcements about the completion of this new center in 2009.

DuPont Environmental Education Center now

DuPont Environmental Education Center now

DuPont Environmental Education Center upon completion

DuPont Environmental Education Center upon completion