Primary and bacterial production in lakes: are they coupled over depth

Abstract. The coupling of prlmary and bacterial production over depth was examined in three lakes which differed greatly in vertical patterns of primary productivity. We measured bacterial production, chlorophyll and light, and estimated primary production in Paul Lake (Gogebic County, Michigan) and Crystal and Trout lakes (Vilas County, Wisconsin) during the summer strat~fication period (May-September 1991). Bacterial productivity was measured using the ['Hlleucine incorporation method and primary productivity estimated from measured photosynthesis-irradiance relationships. Three distinct vertical patterns were observed. In Paul Lake, bacterial production was highest at the interface between the aerobic and anaerobic layers, well below the depth of maximum primary production. In Crystal Lake, bacterial production was uniform with depth, although primary b 4-' gaductivity was highest in the hypolimnion. In the largest lake, Trout Lake, primary and bacterial production tended to co-vary with maximum rates of both processes occurring in the metalimnion. Overall, bacterial productivity was poorly related to contemporaneous primary production in the three lakes, suggesting that other factors, such as nutrient recycling, phytoplankton loss rates and allocthonous loading, determine patterns in the depth distribution of bacterial productivity

Junior Recital: Stacey L. Novik, trumpet

This recital is presented in partial fulfillment of requirements for the degree Bachelor of Music in Performance. Ms. Novik studies trumpet with Lester Walker.https://digitalcommons.kennesaw.edu/musicprograms/1041/thumbnail.jp

Prevelance of Tinea Pedis and Onychomycosis in Malta : the Achilles project

The Achilles project was set up because of the general poor awareness of foot disease, espe- cially of fungal foot infections. Foot diseases are often not viewed as a real problem, and the general public has limited knowledge of them. Most previous studies have involved small and specific population groups, such as school children, subjects visiting swimming baths, populations with specific occupations, or patients with underlying diseases like diabetes. Moreo- ver, patients often had to diagnose the condition themselves. The results of these self-assess- ments, was an underestimation of the prevalence of foot infections. (1, 2) The Achilles project was the largest epidemiological study ever to be carried out on foot health in Europe and other countries, related to the part of the body below the Achilles heel (e.g. foot, toes, toenails). Started in 1998, the aim of the project was to gain a better understanding of diseases affecting the feet and their prevalence among different patient groups with a view to improve the timely diagnosis and optimal treatment of this significant medical problem. The project also allowed an insight to be gained into the predisposing factors and quality of life in a large population, and to generate clinical data from a sample of the population. The data also served as the basis for epidemiological studies, allowing both medical professionals and pa- tients to benefit from this knowledge. The ultimate goal is therefore to increase the chance for timely diagnosis and treatment of foot disorders. Several European countries, including Austria, Belgium, the Czech Republic, Germany, Greece, Hungary, Italy, Luxembourg, the Netherlands, Portugal, Poland, Russia, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom (UK), have thus far participated in this foot-screening project, which was endorsed by the European Academy of Dermatology and Venerology (EADV) and the European Nail Society. Following the example of these countries, in 1999 Malta, Jordan and Cyprus implemented the Achilles project.peer-reviewe

Trophic Cascades, Nutrients, and Lake Productivity: Whole-Lake Experiments

Responses of zooplankton, pelagic primary producers, planktonic bacteria, and CO2 exchange with the atmosphere were measured in four lakes with contrasting food webs under a range of nutrient enrichments during a seven-year period. Prior to enrichment, food webs were manipulated to create contrasts between piscivore dominance and planktivore dominance. Nutrient enrichments of inorganic nitrogen and phosphorus exhibited ratios of N:P \u3e 17:1, by atoms, to maintain P limitation. An unmanipulated reference lake, Paul Lake, revealed baseline variability but showed no trends that could confound the interpretation of changes in the nearby manipulated lakes. Herbivorous zooplankton of West Long Lake (piscivorous fishes) were large-bodied Daphnia spp., in contrast to the small-bodied grazers that predominated in Peter Lake (planktivorous fishes). At comparable levels of nutrient enrichment, Peter Lake\u27s areal chlorophyll and areal primary production rates exceeded those of West Long Lake by factors of approximately three and six, respectively. Grazers suppressed pelagic primary producers in West Long Lake, relative to Peter Lake, even when nutrient input rates were so high that soluble reactive phosphorus accumulated in the epilimnions of both lakes during summer. Peter Lake also had higher bacterial production (but not biomass) than West Long Lake. Hydrologic changes that accompanied manipulation of East Long Lake caused concentrations of colored dissolved organic carbon to increase, leading to considerable variability in fish and zooplankton populations. Both trophic cascades and water color appeared to inhibit the response of primary producers to nutrients in East Long Lake. Carbon dioxide was discharged to the atmosphere by Paul Lake in all years and by the other lakes prior to nutrient addition. During nutrient addition, only Peter Lake consistently absorbed CO2 from the atmosphere, due to high rates of carbon fixation by primary producers. In contrast, CO2 concentrations of West Long Lake shifted to near-atmospheric levels, and net fluxes were near zero, while East Long Lake continued to discharge CO2 to the atmosphere

Incidence and Outcomes of Acute Implant Extrusion Following Anterior Cervical Spine Surgery.

STUDY DESIGN: Multi-institutional retrospective case series of 8887 patients who underwent anterior cervical spine surgery. OBJECTIVE: Anterior decompression from discectomy or corpectomy is not without risk. Surgical morbidity ranges from 9% to 20% and is likely underreported. Little is known of the incidence and effects of rare complications on functional outcomes following anterior spinal surgery. In this retrospective review, we examined implant extrusions (IEs) following anterior cervical fusion. METHODS: A retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network. Medical records for 17 625 patients who received cervical spine surgery (levels from C2 to C7) between January 1, 2005, and December 31, 2011, were reviewed to identify occurrence of 21 predefined treatment complications. RESULTS: Following anterior cervical fusion, the incidence of IE ranged from 0.0% to 0.8% across 21 institutions with 11 cases reported. All surgeries involved multiple levels, and 7/11 (64%) involved either multilevel corpectomies or hybrid constructs with at least one adjacent discectomy to a corpectomy. In 7/11 (64%) patients, constructs ended with reconstruction or stabilization at C7. Nine patients required surgery for repair and stabilization following IE. Average length of hospital stay after IE was 5.2 days. Only 2 (18%) had residual deficits after reoperation. CONCLUSIONS: IE is a very rare complication after anterior cervical spine surgery often requiring revision. Constructs requiring multilevel reconstruction, especially at the cervicothoracic junction, have a higher risk for failure, and surgeons should proceed with caution in using an anterior-only approach in these demanding cases. Surgeons can expect most patients to regain function after reoperation

Quantifying the effects of commercial clam aquaculture on C and N cycling : an integrated ecosystem approach

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Coastal and Estuarine Research Federation for personal use, not for redistribution. The definitive version was published in Estuaries and Coasts 39 (2016): 1746–1761, doi: 10.1007/s12237-016-0106-0.Increased interest in using bivalve cultivation to mitigate eutrophication requires a comprehensive understanding of the net carbon (C) and nitrogen (N) budgets associated with cultivation on an ecosystem scale. This study quantified C and N processes related to clam (Mercenaria mercenaria) aquaculture in a shallow coastal environment (Cherrystone Inlet, VA) where the industry has rapidly increased. Clam physiological rates were compared with basin-wide ecosystem fluxes including primary production, benthic nutrient regeneration, and respiration. Although clam beds occupy only 3% of the ecosystem’s surface area, clams filtered 7-44% of the system’s volume daily, consumed an annual average of 103% of the phytoplankton production, creating a large flux of particulate C and N to the sediments. Annually, N regenerated and C respired by clam and microbial metabolism in clam beds were ~3-fold and ~1.5-fold higher, respectively, than N and C removed through harvest. Due to the short water residence time, the low watershed load, and the close vicinity of clam beds to the mouth of Cherrystone Inlet, cultivated clams are likely subsidized by phytoplankton from the Chesapeake Bay. Consequently, much of the N released by mineralization associated with clam cultivation is ‘new’ N as it would not be present in the system without bivalve facilitation. Macroalgae that are fueled by the enhanced N regeneration from clams represents a eutrophying process resulting from aquaculture. This synthesis demonstrates the importance of considering impacts of bivalve aquaculture in an ecosystem context especially relative to the potential of bivalves to remove nutrients and enhance C sinks.This work was supported by Virginia Sea Grant (NA10OAR4170085, #R/71515W, #R/715168), the NSF GK12 Fellowship (DGE-0840804), the Strategic Environmental Research and Development Program – Defense Coastal/Estuarine Research Program Project SI-1413, and NSF Virginia Coast Reserve LTER Project (DEB 0080381, DEB 0621014).2017-05-1