75 research outputs found
Coastal squeeze on temperate reefs: Long-term shifts in salinity, water quality, and oyster-associated communities
Foundation species, such as mangroves, saltmarshes, kelps, seagrasses, and oysters, thrive within suitable environmental envelopes as narrow ribbons along the landâsea margin. Therefore, these habitat-forming species and resident fauna are sensitive to modified environmental gradients. For oysters, many estuaries impacted by sea-level rise, channelization, and municipal infrastructure are experiencing saltwater intrusion and water-quality degradation that may alter reef distributions, functions, and services. To explore decadal-scale oysterâreef community patterns across a temperate estuary in response to environmental change, we resampled reefs in the Newport River Estuary (NRE) during 2013â2015 that had previously been studied during 1955â1956. We also coalesced historical NRE reef distribution (1880sâ2015), salinity (1913â2015), and water-quality-driven shellfish closure boundary (1970sâ2015) data to document environmental trends that could influence reef ecology and service delivery. Over the last 60â120 years, the entire NRE has shifted toward higher salinities. Consequently, oysterâreef communities have become less distinct across the estuary, manifest by 20%â27% lower species turnover and decreased faunal richness among NRE reefs in the 2010s relative to the 1950s. During the 2010s, NRE oysterâreef communities tended to cluster around a euhaline, intertidal-reef type more so than during the 1950s. This followed faunal expansions farther up estuary and biological degradation of subtidal reefs as NRE conditions became more marine and favorable for aggressive, reef-destroying taxa. In addition to these biological shifts, the area of suitable bottom on which subtidal reefs persist (contracting due to up-estuary intrusion of marine waters) and support human harvest (driven by water quality, eroding from up-estuary) has decreased by >75% since the natural history of NRE reefs was first explored. This âcoastal squeezeâ on harvestable subtidal oysters (reduced from a 4.5-km to a 0.75-km envelope along the NRE's main axis) will likely have consequences regarding the economic incentives for future oyster conservation, as well as the suite of services delivered by remaining shellfish reefs (e.g., biodiversity maintenance, seafood supply). More broadly, these findings exemplify how âsqueezeâ may be a pervasive concern for biogenic habitats along terrestrial or marine ecotones during an era of intense global change
Managerial Decision Making: Comparison of Participative Decision Methods in Australian and Singaporean/Hong Kong Chinese Samples
The impact of employee perceptions of training on organisational commitment and turnover intentions: a study of multinationals in the Chinese service sector.
This study examines the impact of employee perceptions of training on organizational commitment, and the latterâs relationship with turnover intentions. Structured equation modelling is conducted on survey data from 437 Chinese employees of five multinational enterprises operating in the Chinese service sector. The results of the survey are consistent with social exchange theory. They highlight the importance of training as a tool to enhance the affective organisational commitment of employees, and reduce turnover. The findings differ from previous studies in non-Chinese settings. No evidence was found of any impact of motivation to learn and perceived benefits of training on organizational commitment. This may be explained by three factors; the involuntary nature of employee training, the limited career development opportunities on offer to local employees of multinational enterprises and the difficulty employees face in applying learnt skills given cultural differences. The implications for research and practice are discussed
Evaluation of the cyclooxygenase selectivity of robenacoxib and its effect on recovery of ischemia-injured jejunal mucosa in horses
Objective-To determine the cyclooxygenase (COX) selectivity of robenacoxib and its effect on recovery of jejunal mucosa following ischemic injury in horses.
Animals-12 healthy horses.
Procedures Half the maximal inhibition (EC50) of robenacoxib for COX-1 and COX-2 activity was established in bloods samples from 6 horses via measurement of thromboxane B-2 (TXB7) and prostaglandin E-2 concentrations, respectively; COX selectivity was subsequently calculated. Six other horses were anesthetized, and ischemia was induced in the jejunum for 2 hours. Control and ischemia-injured mucosa were collected and incubated with Ringer's solution (control treatment), flunixin meglumine (2.7 X 10(-5)M), or robenacoxib (2.7 X 10(-5)M). Transepithelial electrical resistance and mannitol flux were measured over a 4-hour recovery period. Bathing solution TXB2 and prostaglandin E metabolite concentrations were measured to assess COX-1 and COX-2 function, respectively.
Results-The mean +/- SD EC50 value of robenacoxib for COX-1 and COX-2 was 11.46 +/- 4.46 mu M and 0.19 +/- 0.07 mu M, respectively, resulting in a COX selectivity ratio of 61.01. The transepithelial electrical resistance of ischemia-injured jejunum treated with flunixin meglumine was significantly lower than that of control and robenacoxib-treated tissues. A significant increase in concentrations of prostaglandin E metabolites and TXB2 was detected in control and robenacoxib-treated tissues but not flunixin meglumine-treated tissues.
Conclusions and Clinical Relevance-Robenacoxib selectively inhibited COX-2 and allowed recovery of barrier function in ischemia-injured equine jejunal tissue in vitro
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