Plant & Animal Life in New Hampshire Lakes
New Hampshire has nearly 1,000 lakes and ponds that support many different forms of wildlife and are important centers of biodiversity. The New Hampshire Division of Forests and Lands defines biodiversity as “the variety and variability of all living organisms.” Biodiversity is threatened when native species suffer extinctions, when invasive species invade and create monocultures and when native habitats are fragmented or destroyed. The incredible diversity of New Hampshire lakes are threatened by many invasive plant and animal species, including milfoil, zebra mussels and largemouth and smallmouth bass.
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Trophic States
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The New Hampshire Department of Environmental Services defines the term “trophic state” as the level of biological production—both plant and animal life—that occur in a lake. Lakes are evaluated based on the following factors: phosphorous levels, chlorophyll levels, water clarity, rooted plant growth and dissolved oxygen. New Hampshire’s lakes fall into three different categories. Lakes in an oligotrophic state are generally large and deep with clear water and rocky, sandy shores. They have limited rooted plant growth. Lakes that fall into the eutrophic state are shallow ponds with mucky bottoms, extensive rooted plant growth, are usually tea-colored and sometimes quite murky from algal growth. The mesotrophic state falls somewhere between the other two trophic states.
Invasive Species
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More than 50 bodies of water in central and southern New Hampshire are infested with invasive aquatic plants. The Department of Environmental Services (DES) is currently working to prevent the introduction of these species by placing “Lake Hosts” at boat landings in lakes around the state. Lake hosts check boats entering lakes for milfoil and other invasives, since boats traveling between bodies of water are one of the main causes of invasive plant transportation; their propeller blades chop up the milfoil and move it around the lake, and small pieces cling to the blades and are transported out of the lake. Invasive species are difficult, if not impossible, to remove once established.
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Milfoil
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Variable-leaf milfoil (Myriophyllum heterophyllum) is a major problem in many New Hampshire lakes. It grows very quickly, and can grow as tall as 15 feet high. It can survive out of water for several hours—when attached to a boat, for example—and quickly revive once it finds its new home. It is difficult to differentiate from some native species making eradication by amateurs difficult. Boats should be cleaned after they exit the water. Hand-pulling the weed when infestations are still small is the best method of control.
Brook Trout
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Brook trout are 1- to 4-lb. fish found in mountain streams, rivers, lakes and ponds. It will only live where summer water temperatures do not exceed 68 degrees Fahrenheit. It is also known as squaretail, speckled trout or brookie. Brook trout are iridescent blue and green with yellow spots on their underside. They are threatened by smallmouth and largemouth bass.
Beavers
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Beavers were completely wiped out by trappers in the 1800s. By the 1950s they had been successfully reintroduced. The beaver is the world’s second largest rodent. Its ability to construct dams with felled trees makes it both beneficial and problematic to its environment. On the one hand, beavers create water impoundments that make important habitats for waterfowl but on the other hand, the dams create flooding of roads and farmland.
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References
- New Hampshire Department of Environmental Services: Water Milfoil
- UNH Extension: Beavers and their Control
- Gulf of Maine Research Institute: Brook Trout
- New Hampshire Division of Forests and Lands: Biodiversity of New Hampshire
- New Hampshire Department of Environmental Services: Layman's Guide for Measuring a Lake's Trophic State
Resources
- Photo Credit swamp beaver image by btanne from Fotolia.com
