Our Research
Introduction:
Del Puerto Canyon is west of Paterson, about 45 minutes from CSU Stanislaus. Our team surveyed habitat conditions and the freshwater invertebrate community at three sites. Our team identified invertebrates and compared communities among three sites and two different sample dates of June and September to examine the biological diversity of the Del Puerto Canyon.
Methods:
In order to sample the riffle habitats we used a D-frame net placed snug against the stream bed. One student would then scrub the rocks and stream bed surface loosening up any benthic invertebrates to be carried by the stream flow into the lodged net.
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In the pool habitat that was present at the Painted Rock location in early fall, we had to use a different tactic for sampling. We performed kick-net sampling. Where one student would kick around the bottom of the lentic (still-water) habitat, and another would quickly scoop the suspended organisms and material into the net.
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The samples were then rinsed to remove excess sediment and then stored in a plastic bottle with 90% ethanol. Later in the lab the samples were sorted and identified to family via dissecting microscope.
Results:
North Fork Location:
The North fork samples were collected in early June and early September. As the North fork site was dry in September, we used a similar site just above of the North fork for the Fall data. At the time of collection both sites were active riffles. One of the unique findings was the discovery of Pteronarcyidae stoneflies which are not usually found in the dry chaparral habitat of Del puerto canyon. These stoneflies prefer alpine environments.
These graphs show the seasonal changes in benthic invertebrate biodiversity measured as a percent. At this site in the summer, we see the major benthic invertebrate order are the Caddisflies (Trichoptera; 46.5%) while at an equivalent site in the fall, the major benthic invertebrate order are the beetles (Coleoptera; 58.2%). Generally speaking both sites have almost the same invertebrate orders but in different amounts. The site in the fall has a lot of coleoptera and trichoptera, while the site in the summer has a lot of trichoptera and diptera (true flies). And some orders appear to be limited to a specific season as megaloptera (hellgrammites) and ephemeroptera (mayflies) are limited to the summer season while plecoptera (stoneflies) and worms (flatworm and roundworm) are limited to the fall.
Painted Rock Location:
At the painted rock location we sampled in early June and mid-September. In early June the habitat was a riffle, that had flowing water and a visible current. When we sampled in mid-September however the habitat had slowed from lotic to a lentic habitat forming a pool.
These graphs show the seasonal change in biodiversity of the benthic invertebrates. The main contributors to BMI biomass are Mollusca (snails), Ephemeroptera (mayflies), and Diptera (true flies) in the early June riffle habitat sample. The main contributors in mid-September changer to Trichoptera (caddisflies), and similar proportions of Mollusca, Diptera, Hemiptera (true bugs), and Coleoptera (beetles).
The food web on the left shows a rough overview of the ecological interactions between animals living in Del puerto canyon. At the base of the food web is the California Roach (fish) and water penny beetle larvae. which feed local insectivorous and piscivorous birds which are then eaten by Coyotes.
Birds (Aves)
Larger Mammalian carnivores
Vertebrate Fish
Terrestrial Invertebrates
Predator Invertebrate Larvae (in the water)
Diatoms on Rock fed on by Grazing Benthic Invertebrate
We took a sample of the dry stream bed and attempted rehydrating it. Benthic invertebrates often lay eggs that go "dormant" over summer when the ephemeral streams dry up. We were able to rehydrate two invertebrate samples a Diptera larve and a Mollusca (snail).
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The rehydration was performed by submerging the soil sample in dechlorinated water with a bubbler for oxygen input.
(left) Video demonstrating the addition of our dry sample to the rehydration tank. (below) the only organism that we managed to revive from the dry sample, it has been identified as a dance fly larvae (Diptera: Empididae)