Large Rivers

   

The large river macrogroup consists of the following aquatic habitat types:







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Cool, Large River

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Distribution: ME, MA, NH, NY, VT. 1,180 miles of habitat in the region, of which 12.0% of the 100m riparian buffer is conserved.

Description: Large, deep, coolwater rivers of the northern region. These very large and deep rivers drain watersheds >1000 sq.mi and have an average bankfull width of 250 feet. Slower moving, lower gradient sections of these rivers are expected to be more unconfined with higher sinuosity, broader floodplain valleys, more riparian wetlands, and lower width/depth ratios than the more moderate gradient portions. Species diversity is high in these rivers, and assemblages characteristic of runs, pools, and the pelagic zone dominate the community. Profundal areas without effective light penetration are also found and support populations of bacteria, fungi, and other decomposers that break down organic matter reaching the bottom. In coastal connected river sections, anadromous species are found. Cool water temperatures in these rivers means the fish community will contain a higher proportion of cool and warm water species relative to coldwater species and few permanent coldwater residents. Examples of this type in the region incluce the Saint John, Allagash, Aroostook, Mattawamkeag, Saint Croix, Piscataquis, Penobscot, Kennebec, Androscoggin, Raquette, Winooski, Saco, Black, Hudson, and Connecticut.

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Warm, Large River

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Distribution: CT, MD, MA, NH, NJ, NY, PA, VT, VA, WV. 3,853 miles of habitat in the region, of which 12.0% of the 100m riparian buffer is conserved.

Description: Large, deep, warmwater rivers of the Mid-Atlantic and low elevations in the north. These very large and deep rivers drain watersheds >1000 sq.mi and have an average bankfull width of 250 feet. Slower moving, lower gradient sections of these rivers are expected to be more unconfined with higher sinuosity, broader floodplain valleys, more riparian wetlands, and lower width/depth ratios than the more moderate gradient portions. Species diversity is high in these large rivers, and assemblages characteristic of runs, pools, and the pelagic zone dominate the community. Profundal areas without effective light penetration are also found and support populations of bacteria, fungi, and other decomposers that break down organic matter reaching the bottom. In coastal connected river sections, anadromous species are often found. Warm water temperatures in these streams means the fish community will contain a higher proportion of warmwater species relative to coolwater species. These systems are unlikely to support any resident coldwater species. Examples of this type in the region include the lower Merrimack, Mohawk, Delaware, Susquehanna, West Branch Susquehanna, Allegheny, Juniata, Ohio, Monongahela, Potomac, South Fork Shenandoah, Kanawha, James, New, and Roanoke.

Download the pdf for this habitat for information about species, crosswalks to state names, and condition of this habitat. ​
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