Vertical migration of the crab Carcinus maenas first zoea in an estuary: implications for tidal stream transport

The first zoea of Carcinus maenas (L.) was intensively sampled in the Canal de Mira (Ria de Aveiro, Portugal) during the winter and spring of 1990. Each sampling period included a series of 25 h fixed-station plankton sampling cycles (12 in winter and 9 in spring), conducted at 1 station located in the lower part of the Canal. Plankton samples were collected every hour, at several depths along the water column, with the use of a pump. Hydrological measurements (salinity, temperature and current velocity and direction) were taken immediately before the collection of the plankton samples. The average depth of the zoeae changed in phase with the tide: larvae reached their highest position in the water column during ebb and their lowest during flood. The extent and phasing of the vertical displacements were such that the first zoea occupied a significantly higher position during the span of the ebb than during flood (p < 0.001). It was also demonstrated that the larvae were significantly closer to the surface during the night (p < 0.05). The pattern of vertical dispersion of the zoeae changed cyclically, with a period equivalent to the tidal half-cycle. Maximum aggregation usually occurred during periods of high current velocity and was independent from water stratification. These observations support the hypothesis that C. maenas first zoea performs an active vertical migration synchronised with tidal and daily cycles. Analysis of the zoeae instantaneous velocity showed that shifts of vertical position according to the phases of tide and day influenced their transport velocity, due to vertical differences of water velocity in the estuarine shear current system. During ebb the larvae were transported at a velocity that exceeded the vertically integrated water velocity; the reverse relationship was observed during flood (p < 0.001). The larvae were also transported faster during the night than during the day (p < 0.05). These results demonstrate that selective tidal stream transport can be generalised in the sense of a unidirectional transport mechanism in estuaries that can enhance exportation

Larval abundance patterns of Carcinus-Maenas (Decapoda, Brachyura) in Canal de Mira (Ria de Aveiro, Portugal)

Larval stages of Carcinus maenas (L.) were intensively sampled in the Canal de Mira (Ria de Aveiro, Portugal) during 2 lunar months: February 12 to March 11 and May 9 to June 7, 1990. Each sampling period included fifteen 25 h fixed-station sampling cycles beginning at intervals of 4 tide cycles. Within each 25 h sampling cycle, plankton samples were collected hourly at several depths using a pump. Analysis of the data from these sampling periods indicated tidal and diel cycles of abundance of first stage C. maenas larvae. A semilunar component was also identified. These patterns were expressed as peaks of abundance during ebb tides, with highest peaks during nocturnal neap ebb tides around the first and last quarters of the moon. Peaks of nocturnal abundance could occur at any time during the night but consistently followed high water. In contrast, megalopae were present in the samples primarily during nocturnal flood tides. Intermediate zoeal stages of C. maenas were not collected. As indicated by an analysis of variance, the main effects of phases of the tide and day on the abundance of first zoeae and megalopae were significant (p < 0.05). These results provide evidence that a component with semilunar periodicity is associated with the release of C. maenas larvae. That the release activity occurs well after sunset is also an additional interesting feature of these observations, inasmuch as larval release in decapods is usually concentrated within the first few hours after dusk. These observations support earlier observations that it is the time during the day-night cycle of high tide, as opposed to tidal amplitude, which is the important factor promoting synchrony with the lunar cycle

Evaluation Of The Niosh Sound Level Meter App In Real Work Settings

With the significant presence of occupational noise exposure, the development of mobile sound measurement applications has been reported. These apps have the potential to help reduce purchasing costs of sampling equipment for small businesses. One of the most promising apps is the National Institute for Occupational Safety and Health (NIOSH) Sound Level Meter (SLM), but most studies on the accuracy of the app have been conducted in controlled labs. The purpose of this study was to examine the differences between the NIOSH SLM and type 2 noise measuring instruments in real work settings. Both short-term and long-term noise sampling was conducted in a metal fabrication shop. Thirteen noise sources, including water jets, lathes, (near) welders, presses, mills, wood planners, circular saws, a laser cutter, a sand blaster, and a deburring machine, were selected for short-term sampling. The average short-term sampling duration was 2.5 minutes, and maximum sound level (Lmax) and A-weighted, equivalent continuous sound level (LAeq) were collected from the app installed on an iPhone 11 and type 2 SLM. Welding/general work area and water jet cutter area were chosen for long-term sampling, with a typical shift length of 8 hours. LAeq, Lmax, dose, projected dose, and time-weighted average (TWA) were collected from the app and type 2 noise dosimeter. For the short-term sampling, an average difference in Lmax between the app and type 2 reference device was +2.2 dB(A) (range 0-7.8 dB(A)). For LAeq, an average difference of -1.4 dB(A) was observed (range 0.1-8.4 dB(A)). One long-term sample taken at the water jet cutter area was interrupted by unknown notification(s), which stopped the data collection. The welding/general work area sample showed a difference of 1.7 dB(A) for Lmax, 2.8 dB(A) for LAeq, a 0.3% difference for projected dose and dose, and a difference of 5.8 dB(A) for TWA. Overall, large variances were observed between the NIOSH SLM and the type 2 reference instruments, indicating that the NIOSH SLM may not be suited to replace professional noise measuring devices, but the app may still be used to get a good approximation for employee noise exposure

Two Small Rural Schools Under Siege: An Oral History 1969-2012

This study is an oral history of the small rural community of Portal, Georgia, its two local schools, and its residents’ successful fight to keep these community schools. Guided by the theoretical framework of critical theory and the works of critical researchers, namely Paulo Freire (1998), Michael Apple (2006), Jean Anyon (2005), and Henry Giroux (2001), one purpose of this study was to discover what we can learn from the experiences of citizens in one small rural community who have been affected by consolidation. Since the account of the relationship between the Portal community and its hometown schools remains untold, another purpose was to produce a written record of some of the events from 1969, the year desegregation was enforced in Bulloch County, Georgia, to 2012, two years after the new Portal Middle High School was completed. The residents of Portal, Georgia, have struggled for nearly four decades to retain their neighborhood public schools citing these institutions as vital members in a partnership with this community. The recommended elimination of these schools was partly due to the small enrollment, limited funds, and perceived isolation from other schools in the Bulloch County district. It is how and why these schools, over time, came to be the disfavored, under-enrolled, and under-subsidized institutions they are today that was explored. The concepts of small size, closeness, and the experience of knowing members of their community were repeatedly stressed by the participants as crucial positive characteristics of the schools and community. The analysis of contention between the Portal community and the members in the more influential areas of Bulloch County revealed an ownership attitude and a manner of condescension toward this community with a chief bias being economic discrimination that essentially linked the Portal children’s education to their parents’ income-tax brackets. The majority of the data was gathered through interviews with five women and three men, all key members of the community whose ages range from their early 30s through their early 70s: Sarah Greene, Ellen Hodges, Tracy Kirkland, Kate Mitchell, Jamie Young, Richard Emerson, William Etheridge, and Gerald Johnson (all names are pseudonyms). The stories were analyzed through a critical lens that examines power relationships and the influence of classism in society

Icons, eclipses and stepping off the train: Vladimir Korolenko and the Ocherk

Russian literature has a reputation for gloomy texts, especially during the late nineteenth century. This volume argues that a \u27fin-de-siècle\u27 mood informed Russian literature long before the chronological end of the nineteenth century, in ways that had significant impact on the development of Russian realism. Some chapters consider ideas more readily associated with fin-de-siècle Europe such as degeneration theory, biodeterminism, Freudian psychoanalysis or apocalypticism, alongside earlier Russian realist texts by writers such as Turgenev, Dostoevsky or Tolstoy. Other chapters explore the changes that realism underwent as modernism emerged, examining later nineteenth-century or early twentieth-century texts in the context of the earlier realist tradition or their own cultural moment. Overall, a team of emerging and established scholars of Russian literature and culture present a wide range of creative and insightful readings that shed new light on later realism in all its manifestations

A Case Study of Single-Sex Biology Classes in a High School in South Georgia

The research on single-sex classrooms, especially in high schools, is at best, sparse. Settings and findings vary so dramatically from one area to another that correlating studies is difficult. However, with the advent of No Child Left Behind (2001), schools have been given the opportunity to explore new and creative ways to increase student achievement. Single-sex classrooms are one of the ways schools across the country are attempting to meet the criteria of NCLB. Some single-sex studies have shown that female students improve test scores in areas that are generally thought of as male-dominated areas, such as math and science; that females feel safer in participating in classes with males absent and opportunities to participate are increased; differences in learning styles can be used to an advantage in single-sex classes; and distractions in the classroom caused by the opposite sex are diminished. This research was conducted in a high school in South Georgia where the biology End-of-Course Tests (EOCTs) for single-sex and coeducational classes were examined. Student questionnaires were also given to the students in these classes. The questionnaires had questions divided into five scales: emotional security, self-efficacy, peer help, participation, and interest in biology. The two teachers who taught the biology classes and the administrator in charge of the classes were interviewed at the conclusion 2 of the semester studied. Each set of data was analyzed for any significant differences between sex, setting, and sex by setting interaction for each scale as well as the EOCTs. This researcher found that in this study there were no differences between the EOCT scores for sex, setting, or sex by setting interaction. However, there were differences found within certain scales in the questionnaire, some favoring coeducational classes and some favoring single-sex classes. The teacher and administrator interviews showed a tendency to favor single-sex classes inasmuch that the teachers believe they affect student achievement by building stronger relationships in single-sex classes, as well as relieving distractions help those who need it the most. The analysis of these tendencies may provide other administrators strategies they could use in implementing single-sex education in their own schools

Community Engagement through an Environmental Studies Lens

Situated within a state strongly identified with pristine nature, our central Maine campus provides a fabulous laboratory for both environmental science and civic engagement. To take full advantage of this fortunate situation, Bates College\u27s Environmental Studies (ES) program includes community civic engagement in many, if not all, of our classes and major requirements. Questions about community, diversity, and civic life help our students grapple with the complexity of environmental challenges, pushing them to consider the many kinds of knowledge essential to addressing problems at both local and more global scales. We strongly believe that a liberal arts environmental education can richly inform our students\u27 future lives, regardless of where our students wind up and whether they continue in a field that is directly related to the environment. Civic engagement is also integral to ES courses in the natural sciences. Central to how the Bates ES program does civic engagement is the question of the sciences\u27 role in evaluating and improving the environmental health of human, plant, and animal communities, and how the discourses of science interact with other ways of considering the meanings and histories of place