3,751 research outputs found
Alternative substrates as a native oyster (Crassostrea virginica) reef restoration strategy in Chesapeake Bay
Get PDFOyster shell for native oyster reef restoration is scarce in Chesapeake Bay and other estuaries (Chapter 1). Consequently, alternative substrates merit consideration in oyster restoration. This dissertation examines the suitability of shell alternatives, including granite, concrete, limestone marl, concrete modules and reefballs with reef surveys and experiments in the Rappahannock and Lynnhaven Rivers of Chesapeake Bay. Oyster recruitment, growth, survival, density, biomass, condition, and disease stress, as well as reef accretion and persistence, were measured. In the Lynnhaven River, intertidal riprap had a mean density of 978 oysters m-2 (165 g AFDM m-2) and peak densities \u3e 2000 oysters m-2 (Chapter 2), which are among the highest abundances on alternative reefs, shell or otherwise. Riprap reefs supported a robust population size structure, signifying consistent annual recruitment and reef sustainability. Riprap age (older \u3e younger) and location influenced reef performance; granite and concrete both supported dense oyster-mussel assemblages. In 2005 and 2007, oyster and mussel population structure, density and biomass were quantified on a novel, subtidal concrete modular reef deployed in 2000 in the Rappahannock River (Chapter 3). The reef was not seeded or harvested. Densities (m-2 river bottom) were very high for oysters (2005: 991 m-2; 2007: 2191 m-2) and mussels (2005: 8433 m-2; 2007: 6984 m-2) and comparable to the highest densities on shell reefs. An adjoining 0.44 ha array of concrete reefs (Steamer Rock) was deployed in 1994 and sampled in 2006. These reefs contained \u3e 4 million oysters and \u3e 30 million mussels. Oysters from both reef systems had low disease prevalence and intensity. In a field experiment (Chapter 4), treatments simulating oyster habitat were placed at three intertidal sites in Long Creek of the Lynnhaven River. Granite had highest oyster recruitment and abundance (density \u3e 1500 m-2 and biomass \u3e 200 g AFDM m-2). Many reefs reached a mature state after two years. By Year 3, some reefs had accreted 15-20 L of shell m-2 river bottom, and contained three year classes; some treatments had \u3e 30 % of live oysters growing on other oysters. Large oysters (\u3e 95 mm shell height) had lower intensities of Dermo infection than smaller (60-90 mm) oysters. These patterns indicate that oyster disease tolerance has developed in these high-salinity waters, and highlight the importance of substrate type and reef location in ecological oyster reef restoration. In summer 2006, nine reefs were constructed at two shoreline sites in the Lynnhaven River (Chapter 5), three each of oyster shell (OS), riprap (RR), and concrete modules (CM). Six reefballs were placed at each site, half pre-seeded with hatchery-reared oysters. Finally, in situ setting of triploid oyster larvae on OS, RR and CM reefs was attempted. After 2.5 yrs, all reefs had high oyster density and biomass (unseeded: 150-1200 m -2, 150-600 g AFDM m-2; seeded: 30-1800 oysters m -2), and sustainable accretion rates (8-15 L m-2 yr -1); diploid and triploid oysters had light Dermo infections. Consequently, alternative substrates can serve as effective oyster reefs under diverse conditions in subtidal and intertidal environments of Chesapeake Bay
Abundance, Biomass and Size Structure of Eastern Oyster and Hooked Mussel on a Modular Artificial Reef in the Rappahannock River, Chesapeake Bay
Get PDFRestoration efforts with native Eastern oyster, Crassostrea virginica, in Chesapeake Bay have been extensive, and there has been a continuing search for reef structures that will be effective under a range of environmental conditions. We quantified population structure, density, abundance and biomass of Eastern oyster and hooked mussel, Ischadium recurvum, on a novel concrete modular reef deployed subtidally (~ 7 m depth) in the lower Rappahannock River during October, 2000. The reef provided 3-D architectural complexity, substrate stability, and extensive surface settlement area (nearly 75 m2 of reef surface over 5 m2 of river bottom). Upon deployment, the reef was neither seeded with oyster spat nor exploited. After 4 ½ years of deployment (May 2005), we took 120 stratified random samples over the reef. The reef had been colonized heavily by oysters and mussels, which recruited and survived at densities per m2 of reef surface area ranging from 28-168 for oysters and from 14- 2177 for mussels. These surface densities on the modular reef translate to 1085 oysters and 8617 mussels per m2 of river bottom, which are among the highest recorded for natural and restored oyster reefs. Hence, the reef supported about 10,000 suspensionfeeding bivalves per m2 of river bottom. The size structure of oysters indicated the presence of four year classes, with approximately half of all oysters more than two years old and therefore of reproductive age. Oyster density per m2 of reef surface area was positively correlated with mussel density up to 2000 mussels per m2 , after which oyster density declined somewhat. This reef apparently provides an architecture that is conducive for settlement, growth and survival of the Eastern oyster and hooked mussel in suitable subtidal habitats, and which should therefore be considered as a viable alternative reef structure for Eastern oyster restoration
Successful recruitment, survival and long-term persistence of eastern oyster and hooked mussel on a subtidal, artificial restoration reef system in Chesapeake Bay
Get PDFRestoration efforts with native eastern oyster, Crassostrea virginica, in Chesapeake Bay and elsewhere have been limited by shell availability, necessitating the use of alternative structures as subtidal reefs, yet these have rarely been evaluated quantitatively. We quantified population structure, density, abundance and biomass of eastern oyster and hooked mussel, Ischadium recurvum, on a concrete modular reef (75 m(2) surface area over 5 m(2) of river bottom) deployed subtidally at 7 m depth in the Rappahannock River, Virginia during October, 2000. After nearly 5 y (May 2005), we took 120 stratified random samples over the reef. The reef was heavily colonized by 28-168 oysters and 14-2177 mussels m(-2) surface area. These densities translate to 1085 oysters and 8617 mussels m(-2) river bottom, which are the highest recorded for artificial oyster reefs. Size structure of oysters reflected four year classes, with over half of oysters more than 1 y old and of reproductive age. Oyster biomass (1663 g dry mass m(-2) river bottom) and condition index were equally high, whereas parasite prevalence and intensity were low. Oyster density correlated positively in a sigmoid fashion with mussel density up to high densities, then declined. This modular reef is one of the most successful artificial reefs for eastern oyster and hooked mussel restoration, and details features that are conducive for successful settlement, growth and survival in subtidal habitats
Why Did the Terrapin Cross the Runway?
Get PDFDiamondback terrapins (Malaclemys terrapin) have been nesting at John F. Kennedy International Airport (JFK) for decades. In 2009, the airport experienced a surge in terrapin activity that led to closing a portion of a runway. Runway closures may delay aircraft traffic at JFK which in turn can cause a ripple effect with delays at airports across the country. During the months of June and July, the terrapin nesting season coincides with peak travel for aircraft passengers with about 1,200-1,300 aircraft movements per day. The airport began collecting data on terrapins in 2010 to help understand the dynamics. From 2000-2012, aircraft struck an average of 3.8 terrapins per year. However, no aircraft were damaged as a result of striking terrapins and there were no other negative effects on flights. The airport did experience operational effects such as brief runway closures in order to move terrapins off runways or taxiways. Data collected from 2010-2012 showed increases from 200 to 1,300 terrapins relocated during the annual nesting season. At peak times, more than 200 terrapins have been relocated in a two-hour period. The dates of the peak nesting activity varied by year; however, there was a peak during the second week of June and no nesting activity observed after 17 July. The number of terrapins nesting and relocated per day was similar in 2011-2012, ranging from about 50-200 terrapins. In contrast, researchers observed 30-50 terrapins nesting each day in 2011-2012 at the nearby Jamaica Bay Wildlife Refuge. Terrapins that were collected in 2010-2012 were also measured to determine plastron and carapace length, marked with shell notches and passive integrated transponder (PIT) tags, and then released. In 2012, over 84% of the terrapins collected were ≤ 160 mm, suggesting that this is a young terrapin population. Terrapins at JFK also captured the attention of media around the world and resulted in positive images of the airport’s wildlife program. Management of terrapins at the airport must take into account the socio-political aspects of the issue, but also address potential safety hazards and operational problems posed by the large numbers of terrapins in the aircraft movement area. The airport was directed by FAA to address the terrapins in 2012 and set up a trial of two different barriers. Trail cameras were used to test the effectiveness of the barriers and provided results that helped to refine our survey techniques
Creative IL embedding at Royal Holloway, University of London 2013
Get PDFn 2013, Helen Westwood and Russell Burke presented at LILAC about how information literacy was embedded in Geography courses at Royal Holloway. One of our plans for the future was to embed IL across the college. In May 2014, a paper was accepted at the College’s Learning, Teaching and Quality Committee making IL training and assessment a requirement for all first year undergraduate courses from 2014/15. This poster will show the steps involved in achieving this outcome, the challenges we have faced, and how we have used a variety of ways to engage staff and students with information literacy.
Our Academic Liaison team is formed of six Information Consultants. We are keen to be creative in the way we deliver IL training and we have used a range of methods in order to make the most of the time we are given for the content. An “Information Literacy for staff” libguide has been developed, which includes an information literacy menu so academics can see what we we offer and choose what they would like us to deliver for their students “a la carte”. We are also using libguides to support our sessions. For example, one has been developed especially for a Geography 1st year core module. This includes a pre-lecture quiz, as well as tabs for the components of IL. In workshops for a range of subjects, we have asked students to suggest keywords on a given topic using padlet.com. In other lectures, we are using the student response system Socrative for instant question and answer segments. We will use screenshots of these on the poster.
We are keen to share and discuss our approach to embedding IL with LILAC delegates and hope this poster will provide inspiration for other institutions
Improving New Hire Turnover Through The Use Of Assessment Tools
Get PDFThis study focuses on one organization’s adoption and use of a specific job matching assessment instrument for all of their hiring decisions over a three-year period. The paper examines the effectiveness of the organization’s hiring assessment tool as a process for reducing their new hire turnover. The results of the study shows a significant improvement (reduction) in the new hire turnover, compared with the previous three-year period without utilizing the tool. These findings are consistent with years of empirical research on personality, consisting of characteristics behavior measurements that predict how an individual behavior in various situations (Greenberg, 1980)
Settlement, Growth, And Survival Of Eastern Oysters On Alternative Reef Substrates
Get PDFRestoration of the native eastern oyster (Crassostrea virginica) has been severely hindered by the dwindling supply and rising costs of fossil and new oyster shell (OS) for use in reef restoration. Consequently, emphasis has shifted to the use of alternative oyster reef materials, which need to be tested for their effectiveness as settlement substrate. Furthermore, low recruitment of wild larvae has also impeded restoration, indicating a need to assess the potential of field setting of cultured larvae. We experimentally examined oyster settlement, growth and survival on unconsolidated OS, vertically embedded oyster shell (ES) in concrete, and concrete Oyster Castles (OC) in field and mesocosm experiments. In addition, we examined settlement success of cultured larvae in the mesocosm experiment. In the field experiment, juvenile recruitment was 3 higher on castles and unconsolidated shell than on embedded shell. Castles retained 4Xthe number of oysters and hosted 5Xthe biomass than embedded shell, and retained 1.5Xthe oysters and hosted 3Xthe biomass than unconsolidated shell. The proportion of live oyster recruits on castles was 1.5Xthat on both embedded and unconsolidated shell. In the mesocosm experiment (90-d postlarval deployment), the castles recruited, retained, and hosted an oyster biomass 4Xhigher than that of unconsolidated and embedded shell. This study confirms that artificial reef materials, such as OC, are suitable alternative substrates for oyster restoration, and remote setting of larvae can be effective under controlled environmental conditions. Future restoration efforts should consider use of alternative reef substrates and field setting of larvae, where recruitment is limited, to maximize oyster recruitment, while simultaneously minimizing the cost of reef restoration
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