From his lab at Loyola University Chicago, aquatic ecologist Tim Hoellein investigates the interactions between common pollutants and organisms in rivers and streams. After several years of investigating microplastics in waterways flowing from Lake Michigan, he has now turned his sights to beginning to document the impact of microplastics carried into the lake.
In this new large-scale study, Hoellein and his team are quantifying how much rivers contribute to the plastic load in Lake Michigan by measuring plastics in water and sediment in several of the largest tributaries feeding the lake. In this twelfth and final issue of UpClose, the award-winning Q&A series gives readers an insider’s view of research on emerging contaminants. Each interview highlights a unique component of emerging contaminant research. Readers also learn about the complex, and sometimes tricky, process of conducting field studies and the potential implications of research on industries and regulations.
“The impacts of emerging contaminants on human and environmental health can be hard to document, let alone understand in the context of other issues facing Lake Michigan and other waterways in the Great Lakes basin,” said Laura Kammin, IISG outreach program leader. “The researchers highlighted in the UpClose series each tell a piece of this very complex story.”
Illinois-Indiana Sea Grant is a part of University of Illinois Extension and Purdue Extension.
This is Illinois is a series focusing on wildlife and waterways found in Illinois. The stories are created in conjunction with the Illinois Water Resources Center.
Voted as the state amphibian in 2005, the eastern tiger salamander is one of 20 species of salamanders found throughout Illinois. As the largest land dwelling salamander in North America, eastern tiger salamanders range in size from 6 to 13 inches. In the wild, salamanders have lived to be 16 years old. Not only are they the largest, but they also have the greatest range of all salamanders, spreading from southeastern Alaska, across the width of the United States and all the way down to the Mexican Plateau. Forests, grasslands, or mashes are common places to find them.
But you might have to look hard, because these salamanders hide beneath rocks and stumps, and burrows up to two feet deep. Sometimes referred to as a mole salamander, this nocturnal species spends the majority of its life in cool, dark places, preferring to dig its own burrows to escape warm temperatures. The best time to see salamanders out in the open is after a rain, at night, or during mating season.
The mating season for tiger salamanders begins in late winter or early spring when the ground begins to thaw. Thawing creates temporary ponds of water, where salamanders migrate to mate. One to two days after courtship, females lay up to 1,000 jelly-like eggs on twigs, leaves, or grass on the bottom of the pond. After hatching, the larvae stay in the pond until two to five months old. Once fully grown, eastern tiger salamanders begin to show the unique markings that earned them their name. The most common marking combination is a black background spotted by yellow or gold. Other possibilities are barred, which have vertical yellow stripes running down the body, as well as blotched, which have irregular markings all around their back.
Although their black and yellow markings act as a warning sign to potential predators, not all animals are scared away so easily. Owls, snakes, badgers, and bobcats are common predators of full-grown salamanders while aquatic insects, and snakes eat the larvae. To further aid in defense against threats, salamanders curl their bodies, close their eyes, and wave their tail high above their lowered head. A sticky, poisonous secretion is then released from their skin, often times flung by the salamander’s tail onto the predator’s face. If done effectively, the predator will retreat—at the minimum—with a burning sensation in its eyes and nose.
Skin plays an essential role in every tiger salamander’s survival. Not only does skin ward off predators by secreting poisons, it is also the site of respiration. To ensure that oxygen and carbon dioxide can be exchanged, mucus is secreted by glands to keep the skin moist. Glands also release chemicals that coordinate mating behavior. Because the skin is such an important organ for salamanders, it is very sensitive to environmental changes. Acid rain, for example, has been known to kill them. After repeated contact from the rain, the high acidity damages the outer skin tissue, making it impossible for the salamander to breathe.
Other environmental changes that cause problems for salamanders include habitat loss, degradation, and fragmentation. Altering the land by channelizing streams, draining wetlands, and clearing forests have added to the reduction of habitat. Even removing temporary ponds causes a reduction in the population by destroying a breeding site or by killing the larvae, depending on the time of year.
In Illinois specifically, the majority of species have a gilled, aquatic, or larval stage when high quality water sources are required. Ensuring that salamanders have access to high quality land and water, large enough to sustain a diverse population, is essential to the survival of this amphibian.
In turn, tiger salamanders eat slugs, worms, snails, and insects while their larvae eat small crustaceans, insect larvae, and tadpoles.
Illinois-Indiana Sea Grant is a part of University of Illinois Extension and Purdue Extension.
Where we take a moment to explore some of the unique and impressive species that call the Great Lakes home.
Skin like a shark, feeding habits akin to those of a whale, and a lifespan comparable to our own—the lake sturgeon is a peculiar species indeed. Found in large lakes and rivers, this toothless, whiskered bottom feeder is the largest, longest living, and one of the most ancient species in the Great Lakes. With an average length of 3-5 feet and a weight of 10-80 pounds, some lake sturgeon have grown to be 8 feet long and 300 pounds. Males typically live around 50 years while females’ lifespans range anywhere between 80-150. And with origins during the late cretaceous period, this species has remained relatively unchanged since the time of the triceratops and the tyrannosaurus rex.
The lake sturgeon’s skeleton is partly cartilaginous. Its body has no scales and is lined with five rows of bony plates called skutes—one on top and two rows along each side. Two pairs of fleshy sensory organs called barbels hang from its shovel-like snout like whiskers to help the lake sturgeon find prey. Its diet consists primarily of benthic organisms—small bottom-dwelling creatures like mussels, snails, crustaceans, aquatic insects—but they have been known to eat small fish. With no teeth, the lake sturgeon uses its snout to dig up whatever prey it finds and then sucks it up through its protractile mouth, filtering out sediment through its gills while digesting the organic material.
As hardy as the lake sturgeon may seem, its population suffered almost incalculable losses in the late 19th century. Initially thought of as a nuisance fish that damaged fishing equipment, lake sturgeon were slaughtered en masse. They’d be buried on shore or lined up to dry in the sun like stacks of timber and later used as fuel for steam ships due to the high oil content of their meat. Over time, lake sturgeon meat and eggs became prized commodities, leading to overfishing and an eventual collapse in population.
Recovery has historically been a challenge due to the lake sturgeon’s naturally slow reproductive cycle, with males only reaching maturity around 15 years of age and females at closer to 20. This in combination with lake and river pollution, habitat loss, and dam activity blocking access to spawning grounds has lead to a long decline of lake sturgeon populations across the U.S. and Canada. As a result, lake sturgeon are listed as an endangered, threatened, or species of special concern by 19 of the 20 states where they are found.
But in recent years, some populations have started to rebound. State and Canadian governments now enforce strict policies that limit the number of sturgeon caught each year. Spawning habitats have been constructed, watersheds have been stocked, and eggs have been raised in artificial cultures. People are also encouraged to report any sightings of lake sturgeon to help get a better idea of their numbers.
***Photo by Great Lakes Aquarium
Jay Beugly has joined the team as IISG’s newest aquatic ecology specialist. Located a Purdue University, he works closely with our research team to increase public awareness of the Michigan City nearshore buoy and help boaters, anglers, and beachgoers make use of the data. He also helps coordinate research and outreach activities on Purdue’s West Lafayette campus.
Jay has a Master’s degree in biology from Ball State University, where his work on river and stream ecology earned him the 2009 Outstanding Graduate Student in Fisheries Award. He is currently working towards a PhD in aquatic community ecology.
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