The introduction of non-native species, species that are not originally from this ecosystem, into a marsh may disrupt the marsh ecosystem and threaten the survival of native species. One species that has recently caused a lot of trouble is the European green crab. This crab species was accidentally carried to the Atlantic coast back in the early s from Europe. Since then, they have become extremely invasive and their numbers have exploded!
Soap opera in the marsh: Coots foil nest invaders, reject impostors
Compared to native crabs, the green crab digs a lot when it searches for food and shelter. This digging uproots eelgrass and causes its population numbers to fall. In many spots where green crabs have been introduced, marshes are now bare and no more grass can grow. Non-native green crabs caught in trap that has been underwater for 25 hours.
The Great Marsh is one of the coastal habitats affected by invasive green crabs. Located on the North Shore of Massachusetts, the Great Marsh is known for being the longest continuous stretch of salt marsh in all of New England. Alyssa is a restoration ecologist who is very concerned with the conservation of the Great Marsh and other important coastal ecosystems.
Invasive grasses have recently altered salt marsh ecosystems throughout the northern hemisphere.
Population genetics of a successful invader: the marsh frog Rana ridibunda in Britain.
On the eastern seaboard of the USA, Phragmites australis has invaded both brackish and salt marsh habitats. Phragmites australis influence on sediments and fauna was investigated along a salinity and invasion-age gradient in marshes of the lower Connecticut River estuary.
Strongest effects were evident in the least saline settings II and III where Phragmites has been present the longest and exists in monoculture. Limited influence was evident in the most saline region I where Phragmites and native salt marsh plants co-occur. The vegetation within Phragmites stands in tidal regions of the Connecticut River generally exhibits taller, but less dense shoots, higher above-ground biomass, and lower below-ground biomass than does the un-invaded marsh flora.
There were lower sediment organic content, greater litter accumulation and higher sediment chlorophyll a concentrations in Phragmites - invaded than un-invaded marsh habitat. Epifaunal gastropods Succinea wilsoni and Stagnicola catascopium were less abundant in habitats where Phragmites had invaded than in un-invaded marsh habitat. Macro-infaunal densities were lower in the Phragmites -invaded than un-invaded habitats at the two least saline sites II and III. Phragmites stands supported more podurid insects, sabellid polychaetes, and peracarid crustaceans, fewer arachnids, midges, tubificid and enchytraeid oligochaetes, and greater habitat-wide taxon richness as measured by rarefaction, than did the un-invaded stands.
The magnitude and significance of the compositional differences varied with season and with site; differences were generally greatest at the oldest, least saline sites II and III and during May, when faunal densities were higher than in September.
However, experimental design and the 1-year study period precluded clear separation of salinity, age, and seasonal effects. Although structural effects of Phragmites on salt marsh faunas are evident, further investigation is required to determine the consequences of these effects for ecosystem function.
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The site is secure. An official website of the United States government Here's how you know. The impact of invasive plants on tidal-marsh vertebrate species: common reed Phragmites australis and smooth cordgrass Spartina alterniflora as case studies. By: Glenn R. Cully Nordby. Large areas of tidal marsh in the contiguous US and the Maritime Provinces of Canada are threatened by invasive plant species.