Showing papers by "Heidelberg University (Ohio) published in 2000"

Recolonization and possible recovery of burrowing mayflies (Ephemeroptera: Ephemeridae: Hexagenia spp.) in Lake Erie of the Laurentian Great Lakes

Abstract: Burrowing mayflies of the genus Hexagenia spp. were widely distributed (ca. 80% of sites) and abundant (ca. 160 nymphs/m2) in the western basin of Lake Erie of the Laurentian Great Lakes in 1929–1930, prior to a period of anoxia in the mid 1950s. Nymphs were absent or rare in the basin between 1961 and 1973–1975. In 1979–1991, nymphs were infrequently found (13–46% of sites) in low abundance (3–40 nymphs/m2) near shore (<7.5 km from shore), but were absent or rare offshore (0–7% of sites at 0–1 nymphs/m2). Increased abundance occurred offshore between 1991 (0% of sites) and 1993 (52% of sites at 7/m2). Annual sampling, beginning in 1995, indicates that nymphs increased in both nearshore and offshore waters. By 1997, nymphs were found throughout the lake (88% of sites) at a mean density 40-fold greater (392/m2) than that observed in 1993 (11/m2). In 1998, the distribution of nymphs remained the same as 1997 (88% of sites) but density declined 3-fold (392 to 134/m2). These data indicate that mayflies have recolonized sediments of western Lake Erie and that their abundance may be similar to levels observed before their disappearance in the mid 1950s. However, prior to the mid 1950s, densities were greater in offshore than nearshore waters, but between 1979 and 1998 greater densities occurred near shore than offshore. In addition, there were two areas in the 1990s where low densities consistently occurred. Therefore, recovery of nymphs in western Lake Erie may not have been complete in 1998. At present we do not know the cause for the sudden recolonization of nymphs in large portions of western Lake Erie. Undoubtedly, pollution-abatement programs contributed to improved conditions that would have ultimately led to mayfly recovery in the future. However, the explosive growth of the exotic zebra mussel, Dreissena polymorpha, undoubtedly diverted plankton foods to bottom substrates which could have increased the speed at which Hexagenia spp. nymphs recolonized sediments in western Lake Erie in the 1990s.

The Evolution of the Functional Role of Trunk Muscles During Locomotion in Adult Amphibians 1

Abstract: SYNOPSIS. The axial musculature of all vertebrates consists of two principal masses, the epaxial and hypaxial muscles. The primitive function of both axial muscle masses is to generate lateral bending of the trunk during swimming, as is seen in most fishes. Within amphibians we see multiple functional and morphological elaborations of the axial musculature. These elaborations appear to be associated not only with movement into terrestrial habits (salamanders), but also with subsequent locomotor specializations of two of the three major extant amphibian clades (frogs and caecilians). Salamanders use both epaxial and hypaxial muscles to produce lateral bending during swimming and terrestrial, quadrupedal locomotion. However during terrestrial locomotion the hypaxial muscles are thought to perform an added function, resisting long-axis torsion of the trunk. Relative to salamanders, frogs have elaborate epaxial muscles, which function to both stabilize and extend the iliosacral and coccygeosacral joints. These actions are important in the effective use of the hindlimbs during terrestrial saltation and swimming. In contrast, caecilians have relatively elaborate hypaxial musculature that is linked to a helix of connective tissue embedded in the skin. The helix and associated hypaxial muscles form a hydrostatic skeleton around the viscera that is continuously used to maintain body posture and also contributes to forward force production during burrowing.

Soil landscape models at different scales portrayed in virtual reality modeling language

Abstract: Most state-of-the-art manipulations and visualizations of soil data use geographic information systems to portray soil landscapes in two dimensions (2-D). Nevertheless, soil attributes are distributed continuously in three dimensions (3-D) across landscapes. The objective of this study was to investigate the use of Virtual Reality Modeling Language (VRML), a 3-D graphics language suitable for stand-alone or browser-based interactive viewing, to create 3-D soil landscape models at different scales. Four different locations in southern Wisconsin were selected to represent pedon, catena, catchment, and soil region scales. Soil data, including texture, cone index, and depth of soil layers, were used in conjunction with topographic attributes to create 3-D soil landscape models. Spatial modeling techniques comprised 2-D and 3-D ordinary kriging. We used Environmental Visualization Software (EVS) to export the geometry of 3-D objects, which were enhanced to include: (i) viewpoints, (ii) Munsell colors, (iii) texture maps, (iv) 3-D cross-section animation, (v) animations such as zooming and rotation, and (vi) primitive shapes to highlight areas of interest. Virtual reality modeling language is capable of describing and visualizing extremely complex shapes, such as complex soil layers or terrain. Visualization of Munsell soil colors was difficult to implement because there is no hardware or software independent color-management system available in VRML. Animation techniques were valuable to high-light specific characteristics of each model. The accessibility of interactive VRML models via the World Wide Web and the portability of these models across platforms facilitate the entry of soil science into the virtual world of cyberspace.

The Professional School Counselor and Accountability.

Abstract: Too often, school counselors are evaluated through a teacher assess ment process, which has little meaning or relevance to the professional school counselor's tasks or role. The unclear definition and confusion surrounding the role may be a result of the historical changes sur rounding this position, the discrepancies in school counselor tasks among counselors themselves, and the lack of a clear definition on the role of the school counselor.

Interpreting the latrines of the Johnson's Island Civil War military prison.

Abstract: Investigations of the prison compound latrines from the Johnson’s Island Civil War Military Prison site provide a unique opportunity to explore a multitude of questions related to military life and POW treatment during the American Civil War. Johnson’s Island (Ohio), a Union prison for Confederate officers, contained special use areas within the compound and their associated latrines which can be evaluated chronologically. Coupled with the extensive primary documentation existing for this prison, investigations to date have centered around how these unique latrines exhibit both the POW experience as well as changing Union policy towards prisoners. These latrines captured lost items, were the repository for primary and secondary deposits reflecting the material culture available to the prisoner at the time, and served as the staging areas for escape attempts.

Freshwater dinoflagellates of belize, c.a.

Abstract: Freshwater dinoflagellates have not previously been reported from Belize, although there has been extensive work with marine dinoflagellates and some work with other freshwater groups. Freshwater dinoflagellates are more frequently observed in standing water and none have been observed in the several streams and rivers sampled since 1990. The goal in 1998 was to examine water samples from small ponds within hours of collection to improve the chance of observing swimming dinoflagellates. A plankton net was used and whole water samples also were collected. A small brown water pond on a peninsula and 30m from the Caribbean yielded a bloom of Thompsodinium intermedium. Dinoflagellates, including Peridinium centenniale, Katodinium sp., and Peridinium sp. in the Umbonatum Group, were observed within “Crocodile pond” and “Lily pond” on the mainland.