The Active World of Vernal Pools

By -

(Image Source: Jason Whalen | Fauna Creative)

Upon first sight of a vernal pool, one might not think much of it. A relatively shallow pool in the midst of the forest, covered with duckweed and decaying leaves, this pool of water seems to be no match for beauty to Big Twin Lake, sitting just across the parking lot. While the vernal pool may be less clear and pristine, it is a valuable ecological space teeming with life.

 (Image Source: Emma Sawyer)

Vernal pools are ponds of water that dry up annually (or biennially) and therefore cannot support longer-term populations such as fish. Eliminating the presence of this significant predator allows amphibians and insects to thrive where they might otherwise have been preyed upon in a different aquatic environment. 

These shallow ponds are ephemeral pools of water that collect from rain and snowmelt in topographical depressions in the spring but will dry up by the end of the summer/beginning of autumn. The water does not drain in spring due to a high water-table in the local area and/or the presence of bedrock or fine-particle materials that do not allow water to filter through (Thomas et al, 2010).

In order to classify as a vernal pool, these ponds must adhere to the following (Thomas et al, 2010):

    1. Flood and dry out often enough to harbor specialized flora and fauna which cope            with such changing hydration, as well as the absence of species that rely on the            presence of  water for their full life cycle.
    2. Remain small and shaded as not to permanently establish as a marsh or wetland.
    3. Lack constant connection to another permanent body of water.

These vernal pools are common in wooded areas in the Eastern and Western Upper Peninsulas (Thomas et al., 2010). In Michigan, there are four species that only occur in vernal pools or are dependent on them: fairy shrimp, wood frogs, spotted salamanders, and blue spotted salamanders (Michigan Nature Association (MNA), 2022). While none of these species are insects, insects play a vital role in the thriving of such species and the vernal habitat as a whole, providing both food and predation to keep the ecosystem in balance.

For more information on vernal pools in Michigan, this short nature-documentary style video created by the Michigan Nature Association and Michigan Vernal Pools Partnership provides interesting visuals and information: Michigan Nature Presents: Ephemeral .

In order to investigate the creatures swimming in the pond, we use the method of dip netting, in which you use nets of canvas and mesh on long poles to collect a sample from the water. This sample is deposited on a white tray, where you can search through your sample for larvae, nymphs, adult insects, other invertebrates, and amphibians. 


(Images Source: Emma Sawyer)

Each student has their own preferred method when it comes to collection, including trawling along the bottom of the pond, a quick and decisive “swish” of the net through the water, and investigating net contents in the water as well as on the trays. 

Among the insect specimens found in Wednesday’s collection were:

- the ever-thrashing midge larvae (order Diptera)
- the fierce water tiger (larval form of diving beetles) (order Coleoptera)
- the damselfly nymph (order Odonata)
- the large and hairy dragonfly nymph (order Odonata)
- zippy true bugs (order Hemiptera)
- water beetles (order Coleoptera)
- mosquito larvae (order Diptera)

(Description: a dragonfly nymph | Image Source: Emma Sawyer)

Besides these entertaining insects, specimens such as the following were spotted:

- tadpoles (both small and black as well as larger bullfrog tadpoles. Along with the            presence of full-grown bullfrogs, the size of these bullfrog tadpoles sparked                      conversation about the possibility of this particular pool not fully drying up in the         last year, as the frogs were able to reach a more advanced part of their life cycle in         the pool.)
- daphnia (common water fleas)
- aquatic worms

(Description: a tadpole | Image Source: Emma Sawyer)

Before this trip, I did not even know about the existence of vernal pools or the life teeming within them. However, after our investigation into the insect world unseen, I will never look at a pool in the woods the same.



Sources

Michigan Nature Association (MNA). Michigan Nature Presents: Ephemeral. 2022. YouTube, https://www.youtube.com/watch?v=vdJDe3bA7j8.
Thomas, S. A., et al. “Vernal Pool.” Michigan Natural Features Inventory, 2010, https://mnfi.anr.msu.edu/abstracts/ecology/Vernal_Pool.pdf.
Whalen, Jason. “Why Michigan’s Short-Lived Vernal Pools Are the ‘Coral Reefs’ of Our Forests.” (Image) Mlive, 29 Mar. 2022, https://www.mlive.com/news/2022/03/why-michigans-short-lived-vernal-pools-are-the-coral-reefs-of-our-forests.html.



Comments

Post a Comment

Popular posts from this blog

Mimicry: Being Masters of Disguise

By Anonymous -
Image
By: Cassidy Herbster, Cari Marota and Malik Mason  First to explain mimicry, it is copying another insect or inanimate object to aid in avoidance of predators and/or catching prey. There are two types of mimicry: batesian and mullerian. Batesian refers to when only the insect who is mimicking benefits while mullerian is when both the model and mimicking insect benefits. Most common way is with coloring. The colors of the bad tasting, venomous, or vicious insect is copied by a different insect to avoid being eaten by a predator, though the copy cat doesn't actually have that defense, it just appears so.  They also use coloring to blend in to catch prey or avoid being prey.  The insect being mimicked is called the model. Insects will not always only mimic other insects, but creatures such as arachnids or reptiles. Mimicry might not be for the whole lifetime of the insect. For example, the larvae of an insect could mimic a predator but grow up and not use mimicry as su...
Read more

Bear Lake Bog

By Anonymous -
Image
            A picture of a wetland bog from the Northern Hemisphere Source: https://infograph.venngage.com/p/176597/bog-biome               From lakeside dunes to old-growth white pine forests, Michigan is enriched with unique ecosystems. Although many of which have been claimed by society for agricultural and suburban means, portions of conserved land have been reserved for public recreation and admiration of wilderness. Wetland bogs are microcosms that serve as host to many unique organisms. While they used to be much more prevalent in the United States, they are still an important ecosystem in the US. This blog will expound on our class’s excursion to a bog named Bear Lake Bog.             Bear Lake Bog is located about six miles south of Au Sable campus and is found between the East Lakes and Bear Lake. We visited this bog on May 22, 2018. We broug...
Read more

Honey Bees and Colony Collapse Disorder

By -
Image
            Beginning in the winter of 2006 to 2007, beekeepers began to notice a significant decline in losses of their hives, as high as 30 to 90 percent for no apparent reason ( Kaplan, 2012 ). The population of honeybees continues to decline today. The disappearance of these honey bees is now known as the colony collapse disorder (or CCD). This is concerning because honeybees play an important role in the pollination of plants, especially for agriculture but the loss of honeybees doesn’t stop there. The honey that honeybees make has significant medicinal properties. Honey provides antioxidants, relief to colds, and when applied to scrapes or wounds, it aids the healing process with its natural antibacterial and antimicrobial properties ( Shock, 2015 ). It promotes digestion. The loss of honeybees is not only a threat to biodiversity but the health of plants and people. Colony losses of managed ...
Read more