Hudson River

Category: Inland Aquatic Biomes.

Geographic Location: North America.

Summary: A unique river that flows both north and south simultaneously because of the incoming tide from the Atlantic Ocean.

The Hudson River is a very unusual river in that instead of flowing in typical high- to low-gradient fashion, it flows both ways (northward and southward, in this case) simultaneously, earning its name Muhheakantuck, the Lenape-Delaware tribal word for river that flows two ways. While freshwater flows down the river from the north, saltwater flows up the river from its mouth at the Atlantic Ocean, creating a layering effect of higher-salinity water on top of lower-salinity water or freshwater.

The river provides a unique habitat for its numerous plants and animals, housing both freshwater and saltwater communities. The diverse flora and fauna population also includes more than 100 nonnative species. The Hudson supports a large human community as well, with people using the river for recreation, drinking water, commercial fishing and shipping. Unfortunately, the Hudson is also heavily polluted from human use, but local organizations as well as federal and local governments are working together to decrease the pollution levels and to preserve the river's ecosystem.

Hydrology and Climate

The Hudson River is 315 miles (507 kilometers) in length, beginning in the Adirondack Mountains from Tear of Clouds Lake. The Hudson River Valley lies almost entirely within the state of New York, except for its last 22 miles (35 kilometers), where it serves as the boundary between New York and New Jersey, before it empties through New York Bay and into the Atlantic Ocean. Over 90 percent of the river's basin drains from New York State, but it also drains from Vermont, Massachusetts, Connecticut, and New Jersey. The basin is connected to the Great Lakes and Lake Champlain through many natural and manmade waterways, which allow for many aquatic species to move back and forth between the Hudson and these lakes.

The Hudson River basin experiences long, cold winters and short, warm summers, and has generally warmer temperatures at the southern end. The average water temperature during the winter months is about 25 degrees F (minus 4 degrees C); the summer range is 70–75 degrees F (21–24 degrees C). Annual precipitation in rainfall for this region is approximately 39 inches (100 centimeters). The mean annual snowfall for the entire Hudson River Basin varies from about 98 inches (250 centimeters) in the northern Hudson Valley, to about 20 inches (50 centimeters) near Manhattan.

The river is divided into three sections by basin drainage: the Upper Hudson, the Mohawk, and the Lower Hudson/Hudson River Estuary. The Upper Hudson contains freshwater and flows south from Mt. Marcy in the Adirondacks to Troy, New York. The Lower Hudson, which is often referred to as the Hudson River Valley, is an estuary and so contains both fresh- and saltwater mixed together, making for a brackish flow.

The 155 miles (250 kilometers) of the river from below the dam at Troy to the Atlantic Ocean flow both south and north simultaneously because of the incoming tide from the ocean and the river's low gradient in this stretch. While the river begins at a high elevation level in the Adirondacks, by the time the Hudson reaches Albany, New York, it has mostly flattened out and only slopes about 5 feet (1.5 meters) during the 155-mile (250-kilometer) stretch to the ocean. The movement of the water in the lower half of the river assists in recycling nutrients throughout the river, creating a rich environment for its inhabitants.

Biota

The Hudson is home to both freshwater and saltwater communities. The upper half of the Hudson is where freshwater communities are located. Diatoms and cyanobacteria are the foundation for the food web in the upper Hudson; they feed the beetle, mayfly, and caddisfly communities. Diatoms and cyanobacteria are also food for the numerous protozoans, rotifers, and copepods, as well as benthic (bottom-dwelling) organisms such as bivalves and amphipods. The copepods and rotifers in turn provide food for larval and juvenile fish.

While the entire Hudson contains more than 200 species of fish, only about 70 of these species live in the Upper Hudson, as the water is colder there. Fish species in the freshwater Hudson include brook trout, dace, shiner, chub, and catfish.

The lower half of the Hudson has a much wider variety of plant and animal life, due to the mixed salinity of the water, as it hosts both freshwater and saltwater creatures. The phytoplankton community consists of diatoms and cyanobacteria, as well as green algae and dinoflagellates. Zooplankton common here include: Eurytemora affinia, Arcartia hudsonica, and Temora longicornis. Other benthic invertebrates in the Lower Hudson are bivalves, amphipods, barnacles, gastropods (snails), crabs, and shrimp. These creatures living in the bottom of the river burrow into the sediment, which accelerates the breakdown of organic matter and assists in recycling nutrients back into the water.

The Hudson boasts 140 rare plants, including one of the three endemic taxas of New York. The unique Hudson River water nymph grows nowhere else on Earth. The plant grows in the southern part of the Hudson, through historically it was quite abundant. While once twenty distinct populations of water nymph existed, as of 2024 only two populations were still known to be extant.

The saline water here is also home to a large population of cordgrass and other submerged aquatic vegetation (SAV) such as green fleece (Codium fragile), sea lettuce, and chenille weed. All of this SAV provide food and shelter to many of the creatures in the river, including the large fish population. The warmer waters of the Lower Hudson are home to many different species of fish, including yellow perch, sunfish, bass, and the anadromous types: sturgeon, shad, and eel. Marine fish are also found in the most southern part of the river; these species include the bay anchovy, cunner bluefish, and winter flounder. Occasionally, marine mammals such as the grey seal, harbor seal, dolphin, and whale can be found in the Lower Hudson, as well.

Human Impact

The human population of the river, especially over the last century, has had a profound effect on the river's ecosystem. Since Henry Hudson discovered the river in 1609, it has been a very important transportation route, and is still used for commercial shipping today. Humans began to physically alter the river to ease navigation beginning in the early 19th century, and deforested the basin to make it more hospitable for human use.

During the 20th century, many companies built factories along the river's banks, and would dump raw sewage as well as other pollutants into the river. General Electric (GE) manufacturing facilities at Hudson Falls and Fort Edward, New York, discharged between 105 and 650 tons (95 and 590 metric tons) of extremely toxic polychlorinated biphenyls (PCBs) into the river from 1947 to 1977. Many of the river's inhabitants were severely poisoned, and fishing was banned because of the fish being too toxic to ingest. This dumping went unchecked until the 1970s, when the federal Clean Water Act was created. In 1977, PCBs were banned in the United States, and in 1983, the U.S. Environmental Protection Agency (EPA) declared a 200-mile (322-kilometer) stretch of the river, from Hudson Falls to New York City, to be a Superfund site requiring cleanup.

Progress has been made on clearing the PCBs from the Hudson, but much PCB pollution still remains. In 2016, some fish populations in the river showed signs of rebounding, and parts of the river were safe to swim in, particularly in the mid-Hudson region. GE played a role in this clean-up, dredging the river to remove 2.75 million cubic yards of PCB-contaminated sediment in 2002, but many of those living near the river felt that the company had not done enough to mitigate the damage caused by its disposal of waste into the river. A report from Scenic Hudson in April 2022 estimated the damage to the river's natural resources caused by GE's PCB contamination to be $11.4 billion. According to the report, the additional dredging required to prevent further harm to natural resources will cost $10.7 billion. The additional dredging is needed to remove PCB contamination in river sediments that will continue to harm wildlife and communities along the river. GE could be liable for the entirety of these costs.

Other ongoing pollution issues that currently affect the river include: urban and agricultural runoff; and heavy metals, dioxin, furans, pesticides and other pollutants. Government agencies, as well as organizations of concerned citizens, are working together to reduce pollution and try to restore the Hudson to its natural state.

Several programs that have been created recently to address the issues of climate change, which are projected to include sea-level rise, more extreme storms, riverbank erosion, earlier spring snowmelt runoff, and higher average air and water temperatures. These effects will put pressure on a range of habitats and species here. The Hudson River is at sea level until it reaches the Federal Dam in Troy, so if the Atlantic Ocean rises from climate change, the river also rises. The Department of Environmental Conservation predicts that by 2080, the Hudson could rise 2 to 4 feet. This will affect the communities on its shores. The New York Department of Environmental Conservation works with the Hudson River Estuary Program to help communities understand projected impacts of climate change and to coordinate regional responses.

Bibliography

Benke, Arthur C. and Colbert E. Cushing, editors. Rivers of North America. Elsevier Academic Press, 2005.

Ferro, John. "Hudson River Cleaner, but Still with Problems." Poughkeepsie Journal, 29 Apr. 2016, www.poughkeepsiejournal.com/story/tech/science/environment/2016/04/29/hudson-river-fact-book-pollution/82263018/. Accessed 27 Sep. 2024.

French, Marie J. "Concerns Raised about Hudson River Cleanup at EPA Public Meeting." Politico, 19 July 2017, www.politico.com/states/new-york/albany/story/2017/07/19/concerns-raised-about-hudson-river-cleanup-at-epa-public-meeting-113521. Accessed 27 Sep. 2024.

Gilson, Roger Hannigan. "Here's How the Rising Hudson River Will Impact All of Us." Times Union, 27 Mar. 2022, www.timesunion.com/hudsonvalley/news/article/Here-s-how-the-rising-Hudson-RIver-will-impact-16940339.php. Accessed 27 Sep. 2024.

Henshaw, Robert E., editor. Environmental History of the Hudson River: Human Uses That Changed the Ecology, Ecology that Changed Human Uses. State U of New York P, 2011.

Levinton, Jeffrey S. and John R. Waldman, editors. The Hudson River Estuary. Cambridge UP, 2006.

"New Report Estimates Billions in Damages for Devastating Contamination of the Hudson River." Scenic Hudson, 12 Apr. 2022, www.scenichudson.org/news/new-report-estimates-billions-in-damages-for-devastating-contamination-of-the-hudson-river/. Accessed 27 Sep. 2024.

Niemisto, Maija Liisa, et al. The Hudson: An Illustrated Guide to the Living River. Rutgers UP, 2022.

Yozzo, David J., et al. Ecological Profile of the Hudson River National Estuarine Research Reserve. National Oceanic and Atmospheric Administration, 2005.