610 research outputs found
Did Reclamation Pollute Black Pond?
The microfossil and geochemical records of a sediment core from Black Pond, Franklin Country, New York, collected in 1999 and representing the last 240 years, were analyzed in order to seek information about possible effects of fisheries management practices, including rotenone treatment (reclamation), on the lake. The core chronology was based upon 210Pb and 137Cs dares, and shows that a pronounced and persistent water quality decline began abruptly in the 1950\u27s. This change occurred close to the time of the first of five reclamations (1957), but the core\u27s temporal resolution is not sufficiently fine to exclude coincidence with the post-reclamation stocking of trout. Despite the uncertainty in attributing Black Pond\u27s water quality change to a single cause, these findings nonetheless call into question widespread assumptions that reclamation and the fisheries management associated with it have no long-term effect on water quality in Adirondack lakes
An Environmental History of Lower St. Regis: Lake Degradation and the Path to Ecological Redemption
This paper examines the environmental history of Lower St. Regis Lake (Franklin County, NY), the historic location of the Paul Smith’s Hotel and the present day site of Paul Smith’s College. Using water quality and fiisheries data collected by students, faculty, and environmental professionals, this article examines ecological changes that have taken place in the lake during the last 50 years. An analysis of lake-bottom sediments also reaches farther back in time to show what Lower St. Regis might have been like long before Paul Smith arrived. The story illustrates the effects of massive loading of phosphorus on water quality, places the lake within the context of the environmental awakening of the late 1960s and early 1970s, and chronicles steps that have been taken move Lower St. Regis Lake from a state of degradation toward “ecological redemption
Halcyornis toliapicus (aves: Lower Eocene, England) indicates advanced neuromorphology in Mesozoic Neornithes
Our recent X-ray micro computer-tomographic (μCT) investigations of Prophaethon shrubsolei and Odontopteryx toliapica from the Lower Eocene London Clay Formation of England revealed the avian brain to have been essentially modern in form by 55 Ma, but that an important vision-related synapomorphy of living birds, the eminentia sagittalis of the telencephalon, was poorly developed. This evidence suggested that the feature probably appeared close to the end of the Mesozoic. Here we use μCT analysis to describe the endocranium of Halcyornis toliapicus, also from the London Clay Formation. The affinities of Halcyornis have been hotly debated, with the taxon referred to the Charadriiformes (Laridae), Coraciiformes (Alcedinidae, and its own family Halcyornithidae) and most recently that Halcyornithidae may be a possible senior synonym of Pseudasturidae (Pan-Psittaciformes). Unlike Prophaethon and Odontopteryx, the eminentia sagittalis of Halcyornis is strongly developed and comparable to that of living species. Like those London Clay taxa, the eminentia sagittalis occupies a rostral position on the telencephalon. The senses of Halcyornis appear to have been well developed. The length of the cochlear duct of the inner ear indicates a hearing sensitivity within the upper range of living species, and enlarged olfactory lobes suggest a reasonable reliance on sense of smell. The optic nerves were especially well developed which, together with the strong development of the eminentia sagittalis, indicates a high degree of visual specialization in Halcyornis. The advanced development of the eminentia sagittalis further supports a Mesozoic age for the appearance of this structure and associated neural architectural complexity found in extant Aves. The eminentia sagittalis of living Psittaciformes is situated caudally on the telencephalon, making a Pan-Psittaciformes relationship unlikely for Halcyorni
Catastrophic drought in the Afro-Asian monsoon region during Heinrich Event 1
Between 18,000 and 15,000 years ago, large amounts of ice and meltwater entered
the North Atlantic during Heinrich Stadial 1. This caused substantial regional
cooling, but major climatic impacts also occurred in the tropics. Here we
demonstrate that the height of this stadial, ca. 17-16,000 years ago ("Heinrich Event
1"), coincided with one of the most extreme and widespread megadroughts of the
last 50,000 years or more in the Afro-Asian monsoon region, with potentially serious
consequences for Paleolithic cultures. Late Quaternary tropical drying commonly is
attributed to southward drift of the Intertropical Convergence Zone, but the broad
geographic range of the H1 Megadrought suggests that severe, systemic weakening
of Afro-Asian rainfall systems also occurred, probably in response to sea surface
cooling
Head Depth and Head Speed During Competitive Backstroke Ledge Starts
Recently, a commercially available starting ‘ledge’ designed to reduce foot slippage during the execution of the backstroke start was introduced in competitive swimming. For the purpose of identifying potential safety consequences, the present study investigated the effect of ledge use on head depths, speeds, and distances in backstroke starts of athletes with no prior or only novice familiarity of the ledge. Competitive backstroke starts were performed with and without ledges by high school-aged (14.5 to 19.2 yr, N = 61) swimmers in 1.52 m of water during a closed testing session. A SIMI Reality Motion System in a calibrated space using three cameras was employed for filming starts. Dependent measures were initial head height (Yset), distance from wall at entry (Xentry), entry angle (Angleentry), horizontal velocity at head entry (XVelentry), resultant velocity at entry (ResVelentry), maximum depth of the center of the head (Ymhd), resultant velocity at maximum head depth (ResVelmhd), and distance from the wall at maximum head depth (Xmhd). The ledge (L) condition showed significant increases compared to the non-ledge (NL) condition in Xentry (L 1.61 ± 0.59 m, NL 1.50 ± 0.53 m, p \u3c .001), ResVelentry (L 3.44 ± 0.97 m·s-1, NL 3.08 ± 1.00 m·s-1, p \u3c .001), Angleentry (L 43.13 ± 16.97°, NL 39.66 ± 18.11°, p = .030), Xmhd (L 4.18 ± 0.58 m, NL 4.09 ± 0.63 m, p = .008), and Ymhd (L 0.54 ± 0.21 m, NL 0.49 ± 0.18,
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