Collectively, Rare, Threatened and Endangered (RTE) species tend to be found only in places with very low levels of impervious land cover. And the distribution of all Maryland imperiled aquatic species has declined over the last 30 years. It is these rare species that define an area such as a state, watershed, or county ecologically and make it unique - different from other areas. Examples are dwarf wedgemussels in the Corsica watershed; tiger salamanders only found in Millington; the Marshyhope creek watershed is the only place in the entire Chesapeake Bay watershed with known extant blackbanded sunfish populations. The federally threatened bog turtle actually tends to do very well in wetlands often associated with pastures, but is not found in areas with much impervious land cover.
The Rare Black Banded Sunfish
Once known from swampy streams and millponds within the Delaware, Choptank, Nanticoke, Wicomico, and Pocomoke river basins on the Delmarva Peninsula, the Blackbanded Sunfish has declined over the past 50 years and is now exceedingly rare in Maryland and Delaware.In response to the regional decline of this species, biologists from the Maryland Department of Natural Resources, Maryland Biological Stream Survey, Department of Natural Resources Fishing and Boating Services, Natural Heritage Program, Frostburg State University, and the Delaware Division of Fish and Wildlife initiated an interstate conservation action strategy in January 2008. The goal of the strategy is to protect Blackbanded Sunfish in Maryland and Delaware by developing and implementing specific conservation actions necessary to protect all populations.
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The Search for the Maryland Darter
The search is on for the Maryland darter, a federally-endangered fish that has not been seen for over 20 years and is feared extinct. Biologists from Frostburg State University, Marshall University in West Virginia, and the Maryland Department of
Natural Resources (MDNR) have teamed up to determine once and for all if this rare species still swims in Maryland waters.
In 2009 and 2010, they will be surveying the waters of the Susquehanna River between Conowingo Dam and Havre
de Grace and three Harford County streams for this exceedingly rare species.
While native (and endemic) species are being lost, non-native species are increasing in Maryland. There has been much recent research relating the success of non-natives to disturbed habitats, especially in urban and urbanizing areas. This process of losing native and gaining non-native, species is called biological homogenization. In an article in Science in 2000 Frank Rahel showed that the fish assemblages in US states are, on average, 7% more similar now that they were before human intervention, due to extinctions and introductions. Maryland watersheds are also much more similar today than they were as little as 30 years ago because of introductions and extinctions that are facilitated by habitat homogenization through urbanization.
The Invasion of the Rusty Crayfish in Maryland
The invasive Rusty Crayfish was discovered by biologists of the Maryland Department of Natural Resources (MDNR) in Marsh Creek, a northern tributary to the Monocacy River, in 2007.This crayfish, a formidable invader and nuisance species that has caused ecological damage in many other regions(http://dnr.maryland.gov/invasives/rustycrayfish.pdf), is believed to have been introduced into the Monocacy River as bait by anglers. It is now highly abundant and reproducing in the northern portion of the river. Since any attempt to eradicate this species would cause undue harm to other aquatic species and would likely prove futile, the department focused its efforts on preventing the spread of Rusty Crayfish by anglers from the Monocacy into other Maryland watersheds.
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Freshwater Mussel relocation
Mussel relocation has been used as a conservation strategy for decades to avoid harm from
infrastructure projects. The success of early relocation projects was largely unknown since they
were rarely monitored and the ecology of most species was poorly understood. Projects that
were monitored often observed high mortality. Critical evaluation was also difficult because
mussels can exist at very low numbers and be buried in the substrate. Prior research developed
guidelines to reduce mortality due to handling, transportation, and stocking. Further study is
needed to determine more effective ways to remove mussels from impact areas and minimize
the risk that the relocation will cause harm to these mussels and populations in refuge habitat.
Stream flow helps shape many of the physical and biological characteristics seen in aquatic ecosystems. Aquatic organisms, like fish, crayfish, aquatic insects, and freshwater mussels, have adapted to a range and variability of flow over time that can be characterized as the natural flow regime. Alteration of natural flow regimes, from direct and indirect actions, has been pervasive for over a century and has generally resulted in the degradation of many streams.
Dam Removal on the Patapsco River
Stream blockages, including road culverts and dams, can pose significant risks to aquatic biodiversity. Due to inadequate designs, many of these man-made structures block the movement of migratory fishes, fragment populations of many resident aquatic animals, and lead to degraded habitat quality through the alterations of water flow and transport of sand and silt. The Patapsco River, located southwest of Baltimore City, is intersected by several dams that are impacting the natural stream communities...
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