Using Physical, Chemical and Biological Indicators to Assess Water Quality on the Ouachita National Forest Utilizing Basin Area Stream Survey Methods

The Ouachita National Forest (ONF) has developed a series of Best Management Practices (BMP\u27s) designed to protect water quality and associated beneficial uses (fisheries, municipal water supplies, etc.). A monitoring program is necessary to document the effectiveness of that protection. The Basin Area Stream Survey (BASS) methodology provides a monitoring link from BMP\u27s to the aquatic ecosystems. The goal of BASS is to identify the physical, chemical and biological characteristics of a stream in a format that will allow comparisons with other streams, and indicate when a stream is being impacted. Six index streams within two ecoregions were selected and inventoried in 1990, 1991, and 1992, to serve as baseline data sources. The South Fork of Alum Creek and Bread Creek represent the upper Ouachita Mountain Ecoregion, Caney Creek and Brushy Creek represent the lower Ouachita Mountain Ecoregion, and Jack Creek and Dry Creek represent the Arkansas River Valley Ecoregion

Aquatic Macroinvertebrates of the St. Francis Sunken Lands in Northeast Arkansas

The primary objective of this study was to survey the aquatic macroinvertebrate diversity of the St. Francis Sunken Lands in northeast Arkansas. Secondary objectives were a determination of their relative abundance and distributional and seasonal patterns. Sixty semi-annual collections were made from 30 stations by sampling each station 2 times for 1 ½ man-hours with a Turtox Indestructible™ dip net. Totals of 243 taxa and 13,952 organisms were recorded for the sample period (August 1987 - July 1988). Each station was assigned to 1 of 4 associations, distinguished by distinct physical factors within the river channels and the immediate watershed. The Old River Channel-Oxbow Association exhibited the most complex and stable community structures; this was attributed to the relative lack of man\u27s alteration of the habitat. The Channelized Ditches-Point Source Pollution Association demonstrated obvious detrimental effects of man\u27s intervention. The relatively simple community structures of the St. Francis Lake-Open Water Association were attributed to the typically homogeneous substrates of this area. The simplest community structures were in the Channelized Ditches- Intense Agriculture Association and were a direct result of man\u27s multiple alterations within the river channels and immediate watershed. Seasonal species diversity indices and numbers of taxa varied inversely with respect to water level. High values occurred during low-water periods, whereas lower values occurred during high-water periods. This inverse relationship was attributed to flooded habitat, which led to population dilution and diminished collecting success

Range Extension of the Paleback Darter

Surveys from 1990 through 1992 resulted in a significant range extension of the paleback darter, Etheostoma pallididorsum, which is endemic to the Ouachita Mountains. Prior to 1990, it had only been collected in the upper Caddo River drainage and a tributary to the Ouachita River below Lake Ouachita. The collections that extended this darter\u27s range occurred in tributaries of the Ouachita River above Lake Ouachita

Larval Chironomids of the St. Francis Sunken Lands in Northeast Arkansas

Sixty semi-annual collections (August 1987-July 1988) were made from 30 stations by sampling each station twice for 1.5 man-hours with an aquatic dipnet. Larval chironomids were mounted on slides and identified at 400-1000 magnifications using a Leitz Dialux 20 EB microscope. A survey of the aquatic macroinvertebrates of the St. Francis Sunken Lands in northeast Arkansas revealed 36 taxa of Order Diptera, Family Chironomidae. The taxa were used to evaluate the general health of the aquatic environment. Stations that were located within the least disturbed areas, which were old river channels and oxbows, contained the highest number of organisms and greatest diversity of taxa per station. Stations that were located either in channelized ditches with intense agricultural activities in the watershed or in the St. Francis Lake area, here the homogeneous substate restricted habitat diversity, contained fewer numbers of organisms and taxa per station

Arkansas Range Extensions of the Eastern Small-Footed Bat (Myotis leibii) and Northern Long-Eared Bat (Myotisseptentrionalis) and Additional County Records for the Silver-Haired Bat (Lasionycteris noctivagans), Hoary Bat (Lasiurus cinereus), Southeastern Bat (Myotis austroriparius), and Rafinesque\u27s Big-Eared Bat (Plecotus rafinesquii)

We continued field studies of bats in non-cave regions of Arkansas from 1989 to present and utilized specimens submitted to the Arkansas Department of Health Rabies Laboratory to establish Arkansas range extensions for the eastern smallfooted bat (Myotis leibii) and northern long-eared bat (Myotisseptentrionalis). In addition, we documented additional county records for the silver-haired bat (Lasionycteris noctivagans), hoary bat (Lasiurus cinereus), southeastern bat (Myotis austroriparius), and Rafinesque\u27s big-eared bat (Plecotus rafinesquii)

Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as risk factors for Alzheimer’s disease

Alzheimer’s disease (AD), the leading cause of dementia, has an estimated heritability of approximately 70%1. The genetic component of AD has been mainly assessed using genome-wide association studies, which do not capture the risk contributed by rare variants2. Here, we compared the gene-based burden of rare damaging variants in exome sequencing data from 32,558 individuals—16,036 AD cases and 16,522 controls. Next to variants in TREM2, SORL1 and ABCA7, we observed a significant association of rare, predicted damaging variants in ATP8B4 and ABCA1 with AD risk, and a suggestive signal in ADAM10. Additionally, the rare-variant burden in RIN3, CLU, ZCWPW1 and ACE highlighted these genes as potential drivers of respective AD-genome-wide association study loci. Variants associated with the strongest effect on AD risk, in particular loss-of-function variants, are enriched in early-onset AD cases. Our results provide additional evidence for a major role for amyloid-β precursor protein processing, amyloid-β aggregation, lipid metabolism and microglial function in AD