What's that stuff in the water?

Fuzzy, mossy blobs
(bryozoans)

Swimming red specks

jellyfish

leeches

slimy spheres on the bottom

Algae

Green hairlike strands, green "cotton candy" and green clumps are formed by filamentous algae. These colonies of microscopic plants live in shallow water on the bottom near shore or on submerged objects. Clouds often form in spring after heavy runoff or following a long hot spell in the summer.

Greenish-yellow clouds that look like cotton candy in shallow water near the shoreline are groups of algae known as metaphyton . Metaphyton, made up of several different kinds of algae, may be a foot or more in length. Unlike the planktonic algae that result in whole-lake blooms, metaphyton do not affect lake transparency and are usually localized phenomena. These kind of algae do not necessarily indicate that there are excess nutrient levels in the water.

R. Bouchard photo

Slimy spheres on the bottom

Gelatinous balls seen on the bottom of lakes, especially in clear lakes where light reaches the bottom or in shallow, calm waters, are colonies of Nostoc, a blue-green algae (cyanobacteria). While they look slimy, the balls are fairly hard and tough, and can range from a fraction of an inch to larger than a golf ball. These algae are not a concern and do not indicate bad water quality. They are also sometimes seen on damp forest floors and in ditches.

Orange slime or fluff

Orange stuff is produced by a group of bacteria that use iron as an energy source. This is the same group of bacteria that create oily sheens. The masses of bacteria excrete slimy or fuzzy-looking material as they grow and reproduce, and the slime becomes coated with rusty iron hydroxide. This is usually a natural phenomenon and is generally associated with acidic soils, however in large amounts (orange fluff that fills a stream bed) iron bacteria might indicate pollution.

Egg masses

Jelly-like masses and clumps floating on the surface of shallow, calm waters or attached to sticks under the water might be the egg masses of insects, fish, or amphibians. Frog eggs usually look like a round mass and float on the water surface. Salamander eggs are huge masses with lots of jelly, and may or may not be attached to plants or sticks below the surface of the water. Toad eggs are laid in a string and usually are attached to plants and sticks. While amphibian eggs are found in masses, fish eggs and other eggs may be found individually or in small groups. Long, flat, purplish ribbons that wrap around plant stems or lie over sand bars and brush are yellow perch eggs. These can be seen in early spring.

Dragonfly eggs on the surface.
K. DeGoosh photo

Female "basket tail" dragonflies (Epitheca spp.) carry a batch of eggs and drag their abdomen across the water surface, depositing the eggs in long gelatinous strings. The eggs are clear to milky white with tiny spots of embryos. Toad eggs look similar but they are larger and more silty in appearance. Also, toad eggs are often right along the shoreline in weedy shallows among plant stems, and dragonfly eggs will be slightly further out in deeper water.

Visit the Maine Dragonfly and Damselfly Survey

There are other jelly-like blobs that can be confused with egg masses. Bryozoans, sometimes seen attached to submerged sticks or docks, are animals similar but unrelated to corals. What looks like an individual is a colony of animals, each with a whorl of swirling tentacles. Different species look different: some are wispy and moss-like (giving rise to a common name of "moss animals"), others are large and round, gelatinous, firm, and slimy to the touch. While they may be unsightly on piers and docks, bryozoans are not a water pollution problem and in fact help to filter water.

Professor Doug Smith's Connecticut River bryozoans

WA Dept. of Ecology bryozoan info

Another educational site from RMIT University

Jelly-like blobs moving freely in the water...are jellyfish! About the size of a quarter, with hundreds of tentacles, the freshwater jellyfish (Craspedacusta sowerbyi) can occur sporadically as populations explode and decline. They are translucent but may have a white or green tinge. Freshwater jellyfish have been found in rivers but prefer standing water and are most likely to be seen in lakes and reservoirs in late summer, just below the water surface. They do have stinging cells but are not harmful to humans. Only small fish and insects are harmed by their stings.

Biologist Matt Scott demystifies jellyfish

Jellyfish Research at Indiana University of PA

New Hampshire jellyfish

Jellyfish on the Animal Diversity Web

Photo courtesy T. Peard

Freshwater sponges

Greenish spongy-looking clumps attached to submerged sticks and plant stems in clear, well-oxygenated lakes might be freshwater sponges. There are about 150 species of freshwater sponges, which are members of the animal kingdom but are often mistaken for aquatic plants or algae. Most sponges are green, because they have algae living in their tissues. Freshwater sponges vary in size from a less than an inch to three feet. They are most commonly seen in summer or fall. They may appear sporadically and be abundant in a lake one year and absent the following year. They are usually finger-shaped, and can look soft or hard. Sponges are strong enough to be picked up without falling apart, unlike many kinds of algae.

More sponge info from Washington State Department of Ecology

Sponges in U. of Alberta's Biological Digital Resource Library

Water mites

Small, red specks swimming in shallow waters are most likely water mites. Often found in and around plant beds, water mites can range in size from a pinhead to a pencil eraser.

With eight legs, water mites look like tiny spiders but closer inspection will show they only have one body part, unlike spiders which have two. They can be other colors as well, but red is the most conspicuous.

More info:

Biologist Bruce Smith, Ithaca College

Water Mite page

Water mite portrait gallery

Leeches

Flattened, worm-like animals that attach to skin and suck blood are leeches. Leeches are typically found in shallow, protected waters, concealed among aquatic plants or under stones, logs and other debris. They are attracted to water disturbance. Leeches are most active on hot summer days. In winter they burrow in mud just below the frost line. When attached to a boat or object pulled from the water, you can see them crawl and wave in the air. Leeches are considered to be tolerant of pollution and may be found in stressed rivers and streams, however they are also found in healthy, productive waters.

Maine DEP

U.S. EPA

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