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College Park, MD, United States

Ailstock M.S.,Anne Arundel Community College | Shafer D.J.,Engineer Research and Development Center | Magoun A.D.,Applied Research and Analysis Inc.
Restoration Ecology

Protocols are now available for seed harvest, storage and germination of several mesohaline and polyhaline species; however, low seedling survival rates point to the need for an increased understanding of factors affecting seedling establishment. Depth of seed burial in sediments and initial seedling growth rates are shown to be limiting factors for photosynthetic competency of Ruppia maritima and Potamogeton perfoliatus. Seedling emergence is inversely proportional to planting depth on sediments ranging in grain size from coarse sands (850 μm) to silt (63 μm). Less than 6% of the seeds of either species emerged when buried to a depth of 3 cm in test sediments. Germination was greatest for seeds placed on the surface of sediments; however, these seedlings were subject to displacement because of the weak and fragile roots produced during early growth. Fine sediments may be more favorable for R. maritima seedling establishment, because seedling emergence and height decreased with increasing sediment grain size. Potamogeton perfoliatus seedlings seem to be more tolerant of a wider range of sediment grain sizes than R. maritima as indicated by the lack of an effect of sediment grain size on P. perfoliatus seed emergence, seedling height, and biomass. Increasing nutrients stimulated seedlings of both species; however, even at the highest concentrations tested, growth, as determined by shoot elongation and leaf and root formation, slowed within 7-10 days. This suggests factors other than mineral nutrients and light limit growth or that growth shifts from aboveground biomass production to belowground vegetative spread. © 2010 Society for Ecological Restoration International. Source

Ailstock M.S.,Anne Arundel Community College | Shafer D.J.,Engineer Research and Development Center | Magoun A.D.,Applied Research and Analysis Inc.
Restoration Ecology

Restoration of submerged aquatic vegetation from seed has been hampered by a lack of information on the appropriate conditions for collecting, processing, and storing seeds prior to dispersal. Seeds must be processed and stored under conditions that maintain seed viability, meet dormancy requirements, and prevent premature germination. This study examined the effects of collection date, processing technique, aeration, storage and induction temperature and salinity, and storage period on seed germination of two mesohaline aquatic species, Potamogeton perfoliatus and Ruppia maritima. Collection date and processing technique were significant factors affecting seed yield from donor populations. Seeds of both species remained viable and germinated best when stored at 4°C, and then exposed to freshwater induction conditions. However, their responses to other factors differed. Aeration during storage was necessary in order to maintain viability of P. perfoliatus seeds, whereas it was unnecessary for R. maritima seeds. Storage in freshwater at 4°C prevented germination of P. perfoliatus seeds, while high salinity during cold storage was necessary to minimize premature germination of R. maritima. Mean germination time of P. perfoliatus was dependent on storage salinity; in contrast, mean germination time of R. maritima seeds was dependent on induction salinity. These differences indicate that the methods required to produce large quantities of underwater plant seed amenable to large-scale restoration efforts must be tailored to the specific requirements of individual species and must consider the range of processes from initial harvest through seed testing prior to field establishment. © 2010 Society for Ecological Restoration International. Source

Rango J.J.,Anne Arundel Community College
Psyche (New York)

Ants were surveyed in three habitats at Mount St. Helens in 2008. The area most impacted by the 1980 eruption is the Pumice Plain. Less impacted is the Blowdown Zone where trees were toppled due to the blast. Two habitats were surveyed in the Pumice Plain varying in vegetation density (Pumice Plain Low-Vegetation (PPLV) and Pumice Plain High-Vegetation (PPHV)), and one habitat was surveyed in the Blowdown Zone (BDZ). Ten ant species were collected with the most species collected from the BDZ habitat and the least from the PPLV habitat. Ant abundance was higher at the BDZ and PPHV habitats than at the PPLV habitat. Ant biodiversity was highest at the BDZ habitat than at the PPHV and PPLV habitats. Significant correlations between ant community parameters and plant community parameters were also found. Few plants in the PPLV habitat may contribute to the lack of ants. High ant species richness at the BDZ habitat may be due to complex plant architecture. Results from this study suggest that ants are important focal species in tracking biotic recovery following disturbances. © 2012 Jessamy J. Rango. Source

Hu R.,Anne Arundel Community College | Feng J.H.,Towson University
ACM Transactions on Accessible Computing

The ability to gather information online has become increasingly important in the past decades. Previous research suggests that people with cognitive disabilities experience challenges when finding information on websites. Although a number of studies examined the impact of various design guidelines on information search by people with cognitive disabilities, our knowledge in this topic remains limited. To date, no study has been conducted to examine how people with cognitive disabilities navigate in different content structures. We completed an empirical study to investigate the impact of different search methods and content structures on the search behavior of people with cognitive disabilities. 23 participants with various cognitive disabilities completed 15 information search tasks under three conditions: browsing a website with a deep structure (4 x 4 x 4 x 4), browsing a website with a broad structure (16 x 16), and searching through a search engine. The results suggest that the participants overwhelmingly preferred the search engine method to the two browsing conditions. The broad structure resulted in significantly higher failure rates than the search engine condition and the deep structure condition. The causes of failed search tasks were analyzed in detail. Participants frequently visited incorrect categories in both the deep structure and the broad structure conditions. However, it was more difficult to recover from incorrect categories on the lower-level pages in the broad structure than in the deep structure. Under the search engine condition, failed tasks were mainly caused by difficulty in selecting the correct link from the returned list, misspellings, and difficulty in generating appropriate search. © 2015 ACM. Source

Harrell II I.L.,Anne Arundel Community College | Bower B.L.,University of North Texas
American Journal of Distance Education

This study examined the student characteristics of learning style, locus of control, computer experience and access, and online course experience on persistence of community college students in online courses. An online survey instrument based on the Barsch Learning Style Inventory (1996), the Abbreviated Measure of Internal-External Locus of Control (1974), and a computer experience scale that was developed by the researchers was completed by 225 students enrolled in online courses at five Florida community colleges. Logistic regression analysis identified a three-variable model (auditory learning style, grade point average, and basic computer skills) that was significant in predicting online student success. Academic and student support interventions are suggested for community college students who may be affected by these predictors. © Taylor & Francis Group, LLC. Source

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