Stromatolites in Hamlin Pool
Shark Bay, Austalia
Courtesy Wayne A. Wurtsbaugh

Exposed stromatolites in the
Great Salt Lake
Utah Division of Wildlife Resources
Great Salt Lake Ecosystem Program

Stromatolites in Shark Bay
(Hamlin Pool) during low tide.
Courtesy Linda L’Ai

Hi I’m Holly Strand.

Shark Bay in Northwest Australia is on my “places to see before I die” list. In a section of the bay called Hamelin Pond, colonies of microbes form hard, dome-shaped, deposits. Called stromatolites, these structures embody one of the oldest forms of life on earth. The fossil record of microbes in older stromatolites date back 3.5 billion years. Their antiquity, abundance, and persistence to modern times make stromatolites a fascinating subject for scientific inquiry.

Basically, stromatolites are layered structures formed primarily by cyanobacteria. This photosynthesizing bacteria changes the pH of the water causing calcium carbonate to precipitate over a mat of bacterial filaments. The minerals, along with grains of sediment in the water, are trapped in a layer of goo that surrounds the bacterial colonies. Then the lower layer bacteria grows upward and penetrates the most recent mineral and sediment layer. When this process is repeated over and over, a stromatolite is formed.

For over 2 billion years stromatolites dominated the shallow seas and formed extensive reef tracts rivaling those of modern coral reefs. However, today, stromatolites are relatively rare. You will usually find them growing in extreme environments, such as hypersaline water or thermal springs.

While Shark Bay boasts a stunning example of a modern stromatolite colony, you don’t have to go all the way to Australia. When lake levels are low, you can easily see them in the Great Salt Lake. They span hundreds of square kilometers in shallow shoreline waters. Some say that the Great Salt Lake contains some of the most extensive areal coverage of living stromatolites in the world.

One of the best places to view them is from the shore near Buffalo Point on Antelope Island. When conditions are clear, you can see them underwater at the mouth of the Great Salt Lake Marina.

More than just memorials to ancient life, the stromatolites also play a vital role in Great Salt Lake ecology. They are the principal habitat for the brine fly larvae and pupae. In turn, brine flies are a critical diet for goldeneye ducks, American avocets and many other water birds.

Thanks to Wayne Wurtsbaugh, from Utah State University’s College of Natural Resources for his support in developing this Wild About Utah episode.

For Wild About Utah, I’m Holly Strand.


Photos: Courtesy Utah Division of Wildlife Resources, Wayne A. Wurtsbaugh and Linda L’Ai
Text: Holly Strand

Sources & Additional Reading:

National Park Service. Stomatolite Fossils. [Accessed August 16, 2011]

Schopf, J.William. Anatoliy B Kudryavtsev; Andrew D Czaja; Abhishek B Tripathi. 2007. Evidence of Archean life: Stromatolites and microfossils. Precambian Research, 158. No. 3-4 pp. 141-155.

UNESCO Shark Bay Western Australia [Accessed August 16, 2011]

University of California Museum of Paleontology. Cyanobacteria: Fossil Record [Accessed August 16, 2011]

Walter, M R. 1983. Archean stromatolites – Evidence of the earth’s earliest benthos
Earth’s earliest biosphere: Its origin and evolution. Princeton, NJ, Princeton University Press.

Wurtsbaugh, W.A. 2009. Biostromes, brine flies, birds and the bioaccumulation of selenium in Great Salt Lake, Utah. Pp. 1-15 In: A. Oren, D. Naftz, P. Palacios & W.A. Wurtsbaugh (eds). Saline Lakes Around the World:Unique Systems with Unique Values. Natural Resources and Environmental Issues, volume XV. S.J. and Jessie Quinney Natural Resources Research Library, Logan , Utah. URL:


Utah’s Oolitic Sand, Photo Courtesy and Copyright Mark Larese-Casanova

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Imagine if prehistoric brine shrimp were responsible for one of the finest examples of architecture in Salt Lake City today.

Okay, so it may be a bit of a stretch, but let me explain. In a previous episode of Wild About Utah, I discussed the life cycle of brine shrimp and the important role that they play in the Great Salt Lake Ecosystem. Well, as the billions of brine shrimp feed on bacteria in Great Salt Lake, they excrete waste in the form of tiny fecal pellets. These pellets, along with sand grains and other bits of debris, eventually settle to the bottom of Great Salt Lake.

In shallow areas of the lake, where wind and waves routinely mix the water, these small particles gradually accumulate layers of calcium carbonate, forming an oolite (spelled o-o-l-i-t-e). This is very similar to how a pearl, also layers of calcium carbonate around a small particle, is formed within the shell of an oyster or mussel. The main difference, aside from a pearl being much larger, is that oolites are typically oblong, rather than round. The beaches on the west side of Antelope Island are a great place to find oolitic sand, which will look and feel as though you have a handful of tiny pearls.

Utah’s Oolitic Sandstone
Photo Courtesy & Copyright
Mark Larese-Casanova

Around 50 million years ago, large fresh- and salt-water lakes covered parts of Utah, and in these areas, vast amounts of sediments, including oolites, were deposited. Over time, these oolites were compressed and cemented together into limestone.

A quarry near Ephraim in Sanpete County supplied oolitic limestone for the construction of the Governor’s Mansion in 1902 and the original Salt Lake City Public Library in 1905. The Library building, located at 15 South State Street, eventually housed the Hansen Planetarium and is now home to the O.C. Tanner flagship store. The building underwent an extensive restoration just a couple of years ago, and now serves as a shining example of neoclassical architecture in our capitol city.

The truth is, there are tens of millions of years separating oolitic limestone from our modern-day brine shrimp. So, we can’t exactly say that prehistoric brine shrimp were responsible for the existence of the O.C. Tanner building. But, it’s fun to imagine precious gems from around the world housed in a beautiful building constructed from the ‘pearls’ of Great Salt Lake.

Historic OC Tanner Building
(formerly the Salt Lake Library
and later the Hansen Planetarium)
Photo Courtesy & Copyright
Mark Larese-Casanova

For Wild About Utah, I’m Mark Larese-Casanova.

Images: Courtesy and copyright Mark Larese-Casanova

Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.
Additional Reading:

Utah Geological Survey

Utah Division of Wildlife Resources, Great Salt Lake Ecosystem Program


The Brine Shrimp of Great Salt Lake

Brine shrimp life cycle, Courtesy University of Utah<br/>Genetic Science Learning Center
Brine shrimp lifecycle
Courtesy University of Utah
Genetic Science Learning Center

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

I can still remember the colorful advertisements for Sea Monkeys in the back of comics books that I read as a child. For just $1.75, I could have a “bowl full of happiness!” It wasn’t until I visited Great Salt Lake thirty years later that I realized what sea monkeys really were. They certainly weren’t tiny, web-footed humans, and they definitely didn’t have little crown-like antennae. But, it was exciting to think that we have an enormous Sea Monkey aquarium right here in Utah.

Sea Monkeys are actually brine shrimp of the genus Artemia, and Great Salt Lake is full of the species Artemia franciscana. These tiny crustaceans, along with the brine fly’s aquatic larvae, are the foundation of the Great Salt Lake Ecosystem. Millions of birds visit Great Salt Lake each year to feed on brine shrimp during migration or while nesting.

Brine shrimp nauplii from the Great Salt Lake, Courtesy USGS see
Brine shrimp nauplii
from the Great Salt Lake
Courtesy USGS

Not much can live in Great Salt Lake, with its salt concentrations as high as 25%. But by adapting to these conditions, brine shrimp avoid many predators and have little competition for the abundant algae and bacteria that grow there.

Beginning in late winter or early spring, as the water temperature increases and there is an influx of fresh water to the lake, brine shrimp hatch from cysts, which are hard-shelled dormant eggs. The brine shrimp larva, also called a nauplius, survives on a yolk sack for the first 12 hours, but then feeds on algae as it grows into an adult.

Some species of Artemia have only females, but the Great Salt Lake population has both males and females. The male can be distinguished by his ‘grasper’ antennae, which almost look like a giant handlebar moustache, and the female can often be seen with two small, orange or pink egg sacs at the base of her tail. When conditions in the lake are good, such as with high oxygen and relatively low salt concentrations, female brine shrimp will give birth to live nauplii. But, if salt concentrations increase due to drought in summer, or when water temperature drops in late fall, females switch to making more cysts to ensure the survival of future generations. As winter passes, and spring starts to make an appearance, the life cycle of the brine shrimp starts all over again.

To learn more about brine shrimp, be sure the visit the Great Salt Lake Institute’s web site at I encourage you to visit Antelope Island State Park where you can catch brine shrimp from the marina on the north end of the island. All you need is a bucket… and a little sense of adventure.


Photos: Courtesy USGS
Brine Shrimp Lifecycle, Courtesy University of Utah Genetic Science Learning Center
Text: Mark Larese-Casanova

Additional Reading:

USGS, Utah Water Science Center, Brine Shrimp and Ecology of Great Salt Lake. (Courtesy Internet Archive Wayback Machine, Apr 15, 2008) Formerly:

Brine Shrimp, Genetic Science Learning Center, University of Utah,

Beavers: The Original Army Corps of Engineers

Beaver with branch in water
Courtesy US FWS,
Steve Hillebrand, Photographer

Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

Beavers and beaver dams are a common feature of the Utah landscape. You’ll see the dams on smaller streams and side channels, constructed of branches, downed trees and mud. The still, deep water of the resulting pond creates ideal conditions for a beaver lodge. Beavers can escape and hide from predators by slipping into the pond and disappearing into the lodge. Beavers also use their ponds to cache their favorite
food—aspen and willow.

Because of their tree cutting and dam making skills, humans tend to have two divergent opinions of beavers: 60-pound nuisance or environmental engineer.

Beaver lodge
Courtesy US FWS
Hans Stuart, Photographer

Beavers are considered a nuisance when they gnaw down trees that humans want to keep. Dams can flood roads or stop up irrigation canals. When beaver activity conflicts with human interests, they—the beavers–are likely to be trapped and killed.

However, beaver activity has many positive environmental consequences that we are just beginning to appreciate. Wetlands created by beaver dams help soak up sediments, improving downstream water quality. Because of beaver dams, the winter snowpack isn’t lost in a short spring pulse, This results in a more constant stream flow through the summer –and that’s important as Utah’s climate is predicted to become drier. Finally, beaver dams enhance habitat for many other fish and wildlife species and plants.

Beaver in pond
Courtesy US FWS
Steve Hillebrand, Photographer

According to Dr. Joe Wheaton, a geomorphologist at Utah State University, there’s a lot of untapped potential for employing beaver engineers in stream and floodplain restoration. Say you want to restore a stream by reconnecting it with its floodplain. You need to excavate channels, redirect stream flow, revegetate and nurture the
area for a long period of time. To accomplish this, you often need a
number of highly trained professionals and some large Tonka toys.

Alternatively –under the right conditions– you might transplant a
colony of beavers and let them apply their vigorous work ethic to your
landscape and get quite satisfying results.

Recognizing that nuisance beavers can be rehabilitated into hard
working wetland engineers and stream habitat restorationists, the Utah
Division of Wildlife Resources has rolled out the state’s first beaver
management plan in 2010. This plan encourages live trapping of entire
families of beavers in nuisance areas and moves them to specific sites where their
environmental services can be appreciated and put to use.

Beaver in snow
Courtesy US FWS

Thanks to the USU College of Natural Resources for supporting this Wild about Utah topic.

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Images: Courtesy US FWS, Photographers: Steve Hillebrand and Hans Stuart,
Text: Holly Strand, Stokes Nature Center

Sources & Additional Reading

Collen, P. and R.J. Gibson. 2001. The general ecology of beavers (Castor spp.), as related to their influence on stream ecosystems and riparian habitats, and the subsequent effects on fish – a review. Reviews in Fish Biology and Fisheries 10: 439–461, 2001. [ Accessed May 1, 2010]

Prettyman, B. 2009. Utah wildlife: Leave it to the beavers. Article in Salt Lake Tribune, October 16, 2009. [ Accessed April 29, 2010]

Smithsonian Castor Canadensis Information Page [ Accessed April 29, 2010]

Big Bend Habitat Restoration Project: A Natural Work of Heart, Open Spaces-A Talk on the Wild Side, US FWS, [Accessed March 31, 2016]

Beaver Dams Strengthened by Humans Help Fish Rebound
60-Second Science – July 25, 2016 – By Jason G. Goldman02:29 Also available through the podcast