Social networks in complex human and natural systems: the case of rotational grazing,weak ties,and eastern US dairy landscapes

Multifunctional agricultural systems seek to expand upon production-based benefits to enhance family wellbeing and animal health, reduce inputs, and improve environmental services such as biodiversity and water quality. However, in many countries a landscape-level conversion is uneven at best and stalled at worst. This is particularly true across the eastern rural landscape in the United States. We explore the role of social networks as drivers of system transformation within dairy production in the eastern United States, specifically rotational grazing as an alternative management option. We hypothesize the importance of weak ties within farmer social networks as drivers of change. In Wisconsin, Pennsylvania, and New York, we conducted 53 interviews with confinement, low-intensity, and rotational grazing dairy producers as well as 35 interviews with associated network actors. Though confinement and grazier networks had similar proportions of strong and weak ties, confinement producers had more market-based weak ties, while graziers had more weak-ties to government agencies and other graziers in the region. These agency weak ties supported rotational graziers through information exchange and cost sharing, both crucial to farmers’ transitions from confinement-based production to grazing systems. While weak ties were integral to initial innovation, farmers did not maintain these relationships beyond their transition to grazing. Of equal importance, grazier weak-tie networks did not include environmental organizations, suggesting unrealized potential for more diverse networks based on environmental services. By understanding the drivers, we can identify barriers to expanding weak tie networks and emergent properties in order to create institutions and policies necessary for change.     

Stewardship and management of freshwater ecosystems: From Leopold's land ethic to a freshwater ethic

1. In 1949, Aldo Leopold formalized the concept of the ‘land ethic’, in what emerged as a foundational and transformational way of thinking about natural resource management, biodiversity conservation, and stewardship in terrestrial systems. Yet, the land ethic has inherent linkages to aquatic ecosystems; Leopold himself conducted research on rivers and lakes, and freshwater ecosystems figured widely in his writing.
2. We reflect on the land ethic and other aspects of Leopold's scholarship to identify key messages that provide insight into the stewardship and management of freshwater ecosystems around the globe. We also frame what we call the ‘freshwater ethic’ around Leopold's legacy. Although Leopold could not have envisaged the stressors affecting modern aquatic ecosystems, his core principles remain salient. These apply not only to ecosystem protection, but also to the ethics of modern conservation economics, sustainability, and the protection of natural capital, in which lakes, rivers, and wetlands now figure prominently.
3. We identify key ‘Aldo-inspired’ recommendations for protecting and restoring freshwater ecosystems in the Anthropocene that emanate directly from his writings (e.g. adopt an ecosystem approach, identify win–win–win scenarios, recognize the irreplaceability of wild waters, and strive for freshwater optimism).
4. In an epoch where links between people and nature are becoming more explicit in environmental management, policy, and governance, we suggest that Aldo Leopold's work illustrates how inspirational, seminal thinkers have offered leadership in this domain. We contend that today there is still much that can be learned from Leopold, especially by the next generation of environmental practitioners, to ensure the effective stewardship of our aquatic ecosystems.
5. We submit that the adoption of a freshwater ethic in parallel with Leopold's land ethic will enhance the stewardship of the world's increasingly threatened fresh waters by raising the profile of the plight of fresh waters and identifying enduring actions that, if embraced, will help conserve and restore biodiversity.

     

Insights into an undescribed high-elevation lake (6,170 m a.s.l.) on Volcán Llullaillaco: A physical and microbiological view

1. High elevation lakes are extreme ecosystems and serve as sentinels of various global changes.
2. An expedition to Volcán Llullaillaco in 1996 discovered an unstudied high-elevation lake (6,170 m a.s.l.) that probably was formed as a result of the past eruptive events or climatic processes such as glacial retreat in the lake basin.
3. This article describes an initial physical characterization of the lake and its microbial communities derived from two sampling expeditions in 2013 and 2016.
4. The microbial community in the lake, with an area between 1.2 and 1.4 ha and a depth of 6.8 m, was dominated by Proteobacteria, Actinobacteria and Haloarchaea. In addition, 26 bacterial isolates were identified within the genera Subtercola, Xylophilus, Rhodanobacter, Mesorhizobium and Pseudomonas.
5. Lago Llullaillaco is one of the highest recorded lakes in the world, and this study highlights the unique microbial diversity of this aquatic ecosystem and the importance of its preservation to understand the complex biological processes under polyextreme conditions.

     

A single application of Cu to field soil has long-term effects on bacterial community structure, diversity, and soil processes

Long-term diversity-disturbance responses of soil bacterial communities to copper were determined from field-soils (Spalding; South Australia) exposed to Cu in doses ranging from 0 through to 4012 mg Cu kg⁻¹ soil. Nearly 6 years after application of Cu, the structure of the total bacterial community showed change over the Cu gradient (PCR-DGGE profiling). 16S rRNA clone libraries, generated from unexposed and exposed (1003 mg Cu added kg⁻¹ soil) treatments, had significantly different taxa composition. In particular, Acidobacteria were abundant in unexposed soil but were nearly absent from the Cu-exposed sample (P<0.05), which was dominated by Firmicute bacteria (P<0.05). Analysis of community profiles of Acidobacteria, Bacillus, Pseudomonas and Sphingomonas showed significant changes in structural composition with increasing soil Cu. The diversity (Simpsons index) of the Acidobacteria community was more sensitive to increasing concentrations of CaCl-extractable soil Cu (Cu_Ext) than other groups, with decline in diversity occurring at 0.13 Cu_Ext mg kg⁻¹ soil. In contrast, diversity in the Bacillus community increased until 10.4 Cu_Ext mg kg⁻¹ soil, showing that this group was 2 orders of magnitude more resistant to Cu than Acidobacteria. Sphingomonas was the most resistant to Cu; however, this group along with Pseudomonas represented only a small percentage of total soil bacteria. Changes in bacterial community structure, but not diversity, were concomitant with a decrease in catabolic function (BioLog). Reduction in function followed a dose-response pattern with Cu_Ext levels (R²=0.86). The EC₅₀ for functional loss was 0.21 Cu_Ext mg kg⁻¹ soil, which coincided with loss of Acidobacteria diversity. The microbial responses were confirmed as being due to Cu and not shifts in soil pH (from use of CuSO₄) as parallel Zn-based field plots (ZnSO₄) were dissimilar. Changes in the diversity of most bacterial groups with soil Cu followed a unimodal response - i.e. diversity initially increased with Cu addition until a critical value was reached, whereupon it sharply decreased. These responses are indicative of the intermediate-disturbance-hypothesis, a macroecological theory that has not been widely tested in environmental microbial ecosystems.     

Effects of Amylopectin/Amylose Starch Ratio on Growth, Body Composition and Glycemic Response of Sunshine Bass Morone chrysops × M. saxatilis

Manipulation of the ratio of amylopectin (α‐[1,4] and α‐[1,6] linked glucose) to amylose (α‐[1,41 linked glucose) starches in the carbohydrate fraction of the diet has been used to improve carbohydrate and lipid metabolism in mammalian models. A 10‐wk feeding trial was conducted to determine the effect of dietary amylopectin/amylose ratio on growth and composition of growth of advanced sunshine bass (Morone chrysops × M. saxatilis) fingerlings (60 g, initial weight). Fish were fed cold‐pelleted, semipurified, isonitrogenous (35% crude protein), isocaloric (3.6 kcaVg protein), isolipidic (5%) diets containing 25% carbohydrate. The carbohydrate fraction of the diets was composed of either glucose, dextrin, 100% amylopectin/0% amylose, 70% amylopectin/30% amylose, or 30% amylopectin/70% amylose. Diets differing in ratios of amylopectin/amylose were achieved by adjusting the proportion of high‐amylopectin (100% amylopectin) to high‐amylose (70% amylose) corn starch. Diets were fed to fish in quadruplicate 76‐L tanks (seven fish/tank) connected to a brackish water (5‐7%v) recirculating culture system with biofiltration. Weight gain ranged from 195 to 236% of initial weight (60 g) and was significantly greater (P < 0.1) for fish fed diets containing 25% carbohydrate as dextrin or as 70% amylose and significantly lower in fish fed diets in which carbohydrate was composed of 30% amylose, 100% amylopectin, or glucose. Feed efficiency ranged from 0.52 to 0.61 and was higher in fish fed the diet containing the highest concentration of amylose and lower in fish fed the diet containing glucose. Hepatosomatic index was highest (2.71) in fish fed the diet containing glucose and lowest (1.401.45) in fish fed diets containing high‐amylose cornstarch. Intraperitoneal fat ratio was distinctly lower in fish fed diets containing some amylose as compared to those fed diets without amylose. Liver lipid was significantly lower (4.8%) in fish fed the diet containing glucose and almost twice as high (7.3‐8.9%) in fish fed the diets containing any starch. Glycogen content of the liver decreased from approximately 12% in fish fed the diet containing glucose to 5% in fish fed the diets containing amylose. Muscle proximate composition and ratio were unaffected by the dietary treatments. Fasting levels (15 h) of blood glucose in fish reared for 10 wk on the diet containing glucose were significantly elevated (5.5 mmol/L) when compared to fasting levels of those that had been reared on diets containing starch (3.4‐1.1 mmol/L). Fish fed the diet containing glucose exhibited maximum blood concentrations (14.6 mmoVL) 4 h postprandial then rapidly declined to nearly fasting levels within 8 h postprandial. In contrast, maximum plasma glucose concentrations in fish fed diets containing starch were roughly half (6.8‐8.1 mmol/L) those of fish fed the diet containing glucose. Blood glucose in fish fed diets containing dextrin or predominantly amylopectin starch remained elevated longer than that of fish fed diets containing glucose or predominantly amylose starch. Glycemic response appeared to decrease with increasing dietary amylose content. These data suggest that feeding diets in which a greater portion of the starch is amylose may be a useful strategy for improving carbohydrate use in sunshine bass.     

Evaluation of the Brucella abortus species-specific polymerase chain reaction assay, an improved version of the Brucella AMOS polymerase chain reaction assay for cattle.

In a blind test, 344 samples representing 80 bacterial isolates were analyzed by the Brucella abortus species-specific polymerase chain reaction (BaSS PCR) assay for the identification and discrimination of B. abortus field strains (wild-type biovars 1, 2, and 4) from 1) B. abortus vaccine strains, 2) other Brucella species, and 3) non-Brucella bacteria. Identical samples were tested in 2 laboratories. Half the samples were fully viable, and half were bacteria that had been killed by methanol fixation. The results in 1 laboratory correctly identified 100% of the samples, resulting in a predictive value of 100% for all categories and 100% sensitivity and specificity under the prescribed conditions. The second laboratory misidentified 31 samples, resulting in a range of 66.7-100% sensitivity, 93.2-99.7% specificity, and 77.3-98.2% predictive values depending on the category. There was no significant difference in viable versus fixed bacteria for either laboratory. Subsequent review of the protocol indicated that contamination was the likely cause of 26 of the 31 erroneous identifications. The results show that the BaSS PCR assay has the potential to be a very reliable screening tool for B. abortus identification. However, the data also provide a cautionary reminder of the importance of preventing contamination in diagnostic PCR.     

Heavy Metal Content of Coho Oncorhynchus kisutch and Chinook Salmon O. tschawytscha Reared in Deep Upwelled Ocean Waters in Hawaii1

Coho (Oncorhynchus kisutch) and chinook salmon (O. tschawyrscha) were reared in seawater pumped from the 600 m depth at the Natural Energy Laboratory of Hawaii. Fish were reared in either 100% deep water at 11 C, or a mixture of 55% deep and 45% surface waters at 17 C. Salmon flesh was analyzed for mercury, zinc, cadmium and lead. Mercury concentration in coho salmon reared at 11 C was significantly lower than the concentration in coho reared at 17 C (P < 0.05), but other heavy metal concentrations in tissue did not differ between the two species or between the two rearing temperatures. Compared with wild salmon from the northwest Pacific Ocean, salmon reared in Hawaii had significantly lower concentrations of mercury and lead (P < 0.05), but significantly higher concentrations of zinc and cadmium. These differences in heavy metal concentration between wild and cultured salmon were most readily explained by differences in the heavy metal content of diets and the lack of heavy metal concentrations in rearing water. The concentration of mercury in salmon tissue was at least 20 times less than the 1.0 μ/g U.S. Food and Drug Administration action level for mercury. Action levels have not been established for zinc, cadmium, and lead.     

Signs of Sympathetic Denervation Associated With a Thoracic Melanoma in a Horse

Sympathetic denervation in a 20-year-old, gray, Thorough-bred-Percheron gelding was manifested by cutaneous hyperthermia and sweating over the right side of the body, demarcated by a line from the withers to the elbow and extending cranially. There was cutaneous hyperthermia over the right side of the head, but other signs of Horner's syndrome (sweating, ptosis, miosis, enophthalmos) were not present. The pattern of cutaneous hyperthermia and sweating was consistent with sympathetic denervation localized to the cervicothoracic ganglion, and thoracic radiographs revealed increased density in the craniodorsal thorax. Cytologic evaluation of a sample of pleural effusion revealed mesothelial cells containing melanin and cells suggestive of melanocytes or melanoblasts. Treatment with oral cimetidine and intrapleural cisplatin was not successful. A necropsy was not performed, but the clinical findings supported a diagnosis of thoracic melanoma involving the cervicothoracic ganglion.