Tanner C.E.,St. Marys College of Maryland |
Parham T.,580 Taylor Avenue
Restoration Ecology | Year: 2010
The use of aquaculture systems to grow the seagrass Zostera marina (eelgrass) from seeds for restoration projects was evaluated through laboratory and mesocosm studies. Along the mid-Atlantic coast of North America Z. marina seeds are shed from late spring through early summer, but seeds typically do not begin to germinate until the late fall. Fall is the optimal season to plant both seeds and shoots in this region. We conducted studies to determine if Z. marina seeds can be induced to germinate in the summer and seedlings grown in mesocosms to a size sufficiently large enough for out-planting in the fall. Seeds in soil-less culture germinated in the summer when held at 14°C, with percent germination increasing with lower salinities. Cold storage (4°C) of seeds prior to planting in sediments enhanced germination and seedling survival. Growth rates of seedlings were significantly higher in nutrient enriched estuarine sediments. Results from preliminary studies were used in designing a large-scale culture project in which 15,000 shoots were grown and out-planted into the Potomac River estuary in the Chesapeake Bay and compared with an equal number of transplanted shoots. These studies demonstrate that growing Z. marina from seeds is an alternative approach to harvesting plants from donor beds when vegetative shoots are required for restoration projects. © 2010 Society for Ecological Restoration International.
Ashton M.J.,580 Taylor Avenue |
Morgan II R.P.,University of Maryland Center for Environmental science |
Stranko S.,580 Taylor Avenue
Environmental Monitoring and Assessment | Year: 2014
In an ongoing effort to propose biologically protective nutrient criteria, we examined how total nitrogen (TN) and its forms were associated with macroinvertebrate communities in wadeable streams of Maryland. Taxonomic and functional metrics of an index of biological integrity (IBI) were significantly associated with multiple nutrient measures; however, the highest correlations with nutrients were for ammonia-N and nitrite-N and among macroinvertebrate measures were for Beck's Biotic Index and its metrics. Since IBI metrics showed comparatively less association, we evaluated how macroinvertebrate taxa related to proposed nutrient criteria previously derived for those same streams instead of developing nutrient-biology thresholds. We identified one tolerant and three intolerant taxa whose occurrence appeared related to a TN benchmark. Individually, these taxa poorly indicated whether streams exceeded the benchmark, but combining taxa notably improved classification rates. We then extracted major physiochemical gradients using principal components analysis to develop models that assessed their influence on nutrient indicator taxa. The response of intolerant taxa was predominantly influenced by a nutrient-forest cover gradient. In contrast, habitat quality had a greater effect on tolerant taxa. When taxa were aggregated into a nutrient sensitive index, the response was primarily influenced by the nutrient-forest gradient. Multiple lines of evidence highlight the effects of excessive nutrients in streams on macroinvertebrate communities and taxa in Maryland, whose loss may not be reflected in metrics that form the basis of biological criteria. Refinement of indicator taxa and a nutrient-sensitive index is warranted before thresholds in aquatic life to water quality are quantified. © 2013 Springer Science+Business Media Dordrecht.
Stranko S.A.,580 Taylor Avenue |
Gresens S.E.,Towson University |
Klauda R.J.,580 Taylor Avenue |
Kilian J.V.,580 Taylor Avenue |
And 3 more authors.
Northeastern Naturalist | Year: 2010
The distribution of imperiled stream fish, crayfish, salamander, and freshwater mussel species of Maryland streams in relation to urban land cover and nonnative species was investigated. Over the last 30 years, extinction or extirpation of 13 stream animal species (including the endemic Etheostoma sellare [Maryland Darter]) was observed within the Piedmont region of Maryland, where urbanization has spread extensively outward from Baltimore and Washington, DC, and many non-native species have become established. The presence of imperiled species in this area was correlated with urbanization and non-native species occurrence. However, correlations with land-cover data were stronger than with non-native occurrence. The majority of sites with imperiled species contained less than 10% urban land cover and less than 5% impervious land cover in their catchments. In contrast, stream reaches with non-native species spanned the entire gradient of urban, agriculture, and forested land cover, with the majority of non-native species persisting in streams with over 60% urban and 40% impervious land cover. The persistence of rare species coincident with introduced species in rural portions of Maryland indicates that habitat degradation (like that typically accompanying urbanization) may be the most important threat limiting the distributions of the rarest species that remain in these streams. Limits on urbanization in areas with rare species are needed to maintain regional and global biological diversity. This is particularly important in areas like Maryland that are anticipating extensive human population and urban growth over the next 30 years.
Golden R.R.,580 Taylor Avenue |
Busch K.E.,580 Taylor Avenue |
Karrh L.P.,580 Taylor Avenue |
Parham T.A.,580 Taylor Avenue |
And 2 more authors.
Restoration Ecology | Year: 2010
In response to systemic losses of submerged aquatic vegetation (SAV) in the Chesapeake Bay (east coast of North America), the U.S. Environmental Protection Agency's (EPA) Chesapeake Bay Program (CBP) and Maryland Department of Natural Resources (MD DNR) have considered SAV restoration a critical component in Bay restoration programs. In 2003, the CBP created the " Strategy to Accelerate the Protection and Restoration of Submerged Aquatic Vegetation in the Chesapeake Bay" in an effort to increase SAV area. As part of this strategy, large-scale eelgrass (Zostera marina) restoration efforts were initiated in the Patuxent and Potomac Rivers in Maryland. From 2004 to 2007, nearly 4 million Z. marina seeds were dispersed over 10 ha on the Patuxent River and almost 9 million seeds over 16 ha on the Potomac River. Z. marina seedling establishment was consistent throughout the project (<4%); however, restored eelgrass survival was highly dependent on restoration site. Restoration locations on the Patuxent River experienced initial Z. marina seedling germination, but no long-term plant survival. Restored Z. marina on the Potomac River has persisted and expanded, both vegetatively and sexually, beyond initial seeding areas. Healthy Z. marina beds now cover approximately five acres of the Potomac River bottom for the first time in decades. The differential success of Z. marina restoration efforts in the two rivers is evidence for the necessity of carefully considering site-specific characteristics when using large-scale seeding methods to achieve successful SAV restoration. © 2010 Society for Ecological Restoration International.