Veronica Lake 8/18/19
In the Lakes Basin there are many ponds and lakes teeming with wildlife. Although they contain many of the species that are found in rivers, they also harbor many of their own unique species. Compared to rivers, ponds and lakes are usually warmer and contain less oxygen. They often, but not always, contain silt and algae in higher concentrations than rivers. Aquatic pond and river dwellers have adapted to these conditions in a variety of ways!
Veronica Lake (above photo) is really more like a pond, with a muddy bottom and lots of algae. Usually by August, it has shrunk to a large puddle. This year there is still a surprising amount of water. Last week my friend Nancy and I, waded out into it and found ourselves surrounded by thousands of fairy shrimp! WOW!!! I went back two days later to photograph them and found several other aquatic species!
Damselfly nymph - Spiny-tailed Fairy Shrimp - Tadpole
When I revisited Veronica Lake, I brought a strainer and bowl to catch and hold specimens. I spent several hours exploring the silted, algae filled waters. Because the water wasn't clear, it was hard to see some of the critters. Most of them were really camouflaged. Can you see the damselfly nymph lying on the horizontal beige plant stem? The fairy shrimp are the pale gray short lines (lots of them) in the middle photo. If you look carefully you should see the tadpole's head right in the middle of the photo on the right.
Spiny-tailed Fairy Shrimp - Streptocephalus sealii
Freshwater Crustaceans!
The most amazing find was the Spiny-tailed Fairy Shrimp. There were thousands of them, measuring 3/4" to 1 1/2" in length! They have 11 pairs of leaf-like legs that ripple as they paddle around on their backs! These legs also serve as their gills, and absorb oxygen out of the water. They have one pair of stalked eyes, and 2 pairs of antennae! They are filter feeders of tiny organisms and plant detritus, and will also scrape algae and detritus off of rocks and sediments. They are preyed on by other aquatic insects, shore/wading birds, and sometimes fish. Their typical life span is 3-4 months. They only live in inland, non-flowing, temporary, fresh (non-marine) water. When they die or their pond dries up, they leave behind thousands of embryonated eggs, or cysts, that will remain dormant until the pond refills. These cysts can remain dormant for decades! WOW!!! Apparently these fairy shrimp used to be more widespread, but as human developments filled in wetlands and vernal pools their numbers have declined. How lucky to see these fascinating crustaceans!
Signal Crayfish - Pacifastucus leniusculus
I investigated about 4 lakes, and 3 ponds since we found the fairy shrimp at Veronica Lake, but haven't found any more fairy shrimp! I did however, find another crustacean at Gold Lake, a Signal Crayfish! We were just going swimming in the lake, when this crayfish ambled past in the shallows! These crayfish are native to North America, west of the Rocky Mountains. They are found in the rivers and lakes in our area. They are primarily nocturnal and shelter in their underwater burrows during the day. They are omnivores and eat fish, frogs, invertebrates, and plants, either living or decomposing. They are preyed on by Great Blue Herons, large fish, River Otters, raccoons, and minks! How lucky to see one in the daylight!
I investigated about 4 lakes, and 3 ponds since we found the fairy shrimp at Veronica Lake, but haven't found any more fairy shrimp! I did however, find another crustacean at Gold Lake, a Signal Crayfish! We were just going swimming in the lake, when this crayfish ambled past in the shallows! These crayfish are native to North America, west of the Rocky Mountains. They are found in the rivers and lakes in our area. They are primarily nocturnal and shelter in their underwater burrows during the day. They are omnivores and eat fish, frogs, invertebrates, and plants, either living or decomposing. They are preyed on by Great Blue Herons, large fish, River Otters, raccoons, and minks! How lucky to see one in the daylight!
Damselfly nymphs - species unknown
Odonates: Dragonflies and Damselflies
Odonata is an order of carnivorous insects encompassing the dragonflies and the damselflies. Dragonflies are generally larger, and perch with their wings held out to the sides; damselflies have slender bodies, and hold their wings over the body at rest.
Immature odonates are referred to as naiads or nymphs. All nymphs are voracious predators feeding on everything from small invertebrates such as mosquito larvae to smaller vertebrates such as fish and frogs.
Nymphs will molt nine to 17 times before becoming an adult. The number of generations per year depends on the species of odonate. When nymphs are ready for their final molt they leave the water and crawl onto the bank or vegetation. They will dry out and their exuvia (exoskeleton) will crack open on their back. They will then pull themselves out of their exuvia, pump up their wings, and dry out. A newly emerged odonate is teneral (soft). A teneral dragonfly or damselfly has glossy wings and the colors on the body are often pale. Several days after emerging, they are hardened completely and will have taken on the colors of an adult.
I caught the above Damselfly nymphs in Veronica Lake. I found one on the bottom of the pond, the other one was clinging to a plant stem. At first I couldn't find any of them, but then one of them moved! As soon as I saw one, 6 or 7 of them magically "appeared". They were so camouflaged I hadn't seen them! Damselfly nymphs are pretty tiny, only about 1/2" in length! Their tail filaments are actually their gills!
Damselfly nymph - Damselfly exuvia
I saw this large, red damselfly nymph in a different section of Veronica Lake, where there were more plant stems. It was obviously a different species than the ones I had caught and photographed! The damselfly exuvia I found on a stem above the surface of the pond. It was so delicately beautiful!
Damselflies - unkown species
These two damselflies are not mating. Either they are about to mate, or they have already mated and the female is about to lay eggs in the water. Some damselflies separate right after mating. Some stay connected until the egg-laying process (oviposition) is completed.
The mating process starts with the male clasping the female on the back of her neck with the claspers on the end of his abdomen. If she is sexually receptive she will raise her abdomen up to his, and sperm will be transferred once they are connected. This is called the "wheel" position, in that the two damselflies form a sort of circle or heart when connected!
Dragonfly Nymph - Dragonfly exuvia
I didn't see any dragonfly nymphs in Veronica Lake, although I looked and looked for them. They are a bit larger than damselfly nymphs, chunkier and wider. I took the above photos last year. I found the adult dragonfly nymph walking across a rock on the edge of Little Deer Lake! The Dragonfly exuvia I found on grasses at Big Bear Lake.
Four-spotted Skimmer - Libellula Quadrimaculata
There were however, lots of adult dragonflies flying and resting at Veronica Lake! Locally, adult dragonflies only live for about two months!
Common Garter Snake - Tadpole
Thamnophis sirtalis - frog species unknown
Amphibians and a Reptile!
I also saw a Common Garter Snake and LOTS of tadpoles in Veronica Lake! I don't know what species the tadpoles were but there were hundreds of them! The following information about the life cycle of a frog came from allaboutfrogs.org.
"7 to 10 days after a tadpole hatches, it will begin to swim around and feed on algae.
After about 4 weeks, the gills start getting grown over by skin, until they eventually disappear. The tadpoles get teeny tiny teeth which help them grate food turning it into soupy oxygenated particles. They have long coiled guts that help them digest as much nutrients from their meager diet as possible. After about 6 to 9 weeks, little tiny legs start to sprout. The head becomes more distinct and the body elongates. By now the diet may grow to include larger items like dead insects and even plants.
The arms will begin to bulge where they will eventually pop out, elbow first.
After about 9 weeks, the tadpole looks more like a teeny frog with a really long tail.
By 12 weeks, the tadpole has only a teeny tail stub and looks like a miniature version of the adult frog. Soon, it will leave the water, only to return again to lay more eggs and start the process all over again!"
The Common Garter Snake was probably eating the tadpoles! They can move about freely on water or land. They prey on fish, toads, frogs, tadpoles, salamanders, leeches, slugs, earthworms, birds and small mammals!
Yellow Pond Lily - Nuphar lutea ssp. polysepala
Pond Plants
Like underwater critters, pond plants are an integral part of a pond's ecosystem. They can shade large sections of a pond, and keep it cool. They provide shelter for a wide variety of aquatic insects, as well as food for ducks, shorebirds, geese, and even muskrats! They even contribute a little to the oxygen content of a pond or lake, although most of the oxygen is made by microscopic phytoplankton.
Pond Plants
Like underwater critters, pond plants are an integral part of a pond's ecosystem. They can shade large sections of a pond, and keep it cool. They provide shelter for a wide variety of aquatic insects, as well as food for ducks, shorebirds, geese, and even muskrats! They even contribute a little to the oxygen content of a pond or lake, although most of the oxygen is made by microscopic phytoplankton.
Potamogeton natans - Sparganium angustifolium
Western Grebe - Common Mergansers
Aechmorphorus occidentalis - Mergus merganser
Gold Lake Birds
A lot of the birds species I see on the North Yuba River also thrive up in the Lakes Basin. We spent a day on Gold Lake and saw a Belted Kingfisher, Ospreys, and Common Mergansers! The abundance of fish has brought them there! To our surprise we also saw a Western Grebe! These birds like to dive for prey, such as fish, crustaceans, and aquatic insects. They live and breed on lakes, but will leave high elevation lakes during the winter. It was really unusual to see one, even though they are listed as being here! I haven't seen one in the Lakes Basin before!
The apples are ripening up. Will the bears start coming around?
I'll talk all about Lakes Basin wildflowers next week. There are still LOTS in bloom!
The sunflowers in our garden are all in bloom, and some have gone to seed.
Are the goldfinches going to arrive soon?
Check back next week for the answers to these questions and more!
If you suddenly stop getting my blog in your email, you need to sign up again. This is a problem with blogspot.com and I can't figure out how to fix it.
Your questions and comments are greatly appreciated!
Please email me at northyubanaturalist@gmail.com. Thanks!
No comments:
Post a Comment