Hypoxia and Sturgeons: report to the Chesapeake Bay Program Dissolved Oxygen Criteria Team

In this essay, three lines of evidence are developed that sturgeons in the Chesapeake Bay and elsewhere are unusually sensitive to hypoxic conditions: 1. In comparison to other fishes, sturgeons have a limited behavioral and physiological capacity to respond to hypoxia. Basal metabolism, growth, and consumption are quite sensitive to changes in oxygen level, which may indicate a relatively poor ability by sturgeons to oxyregulate. 2. During summertime, temperatures >20 C amplify the effect of hypoxia on sturgeons and other fishes due to a temperature*oxygen "squeeze" (Coutant 1987)- In bottom waters, this interaction results in substantial reduction of habitat; in dry years, nursery habitats in the Chesapeake Bay may be particularly reduced or even eliminated. 3. While evidence for population level effects by hypoxia are circumstantial, there are corresponding trends between the absence of Atlantic sturgeon reproduction in estuaries like the Chesapeake Bay where summertime hypoxia predominates on a system-wide scale. Also, the recent and dramatic recovery of shortnose sturgeon in the Hudson River (4-fold increase in abundance from 1980 to 1995) may have been stimulated by improvement of a large portion of the nursery habitat that was restored from hypoxia to normoxia during the period 1973-1978. (PDF contains 26 pages

Mill’s Fallacies: Theory and Practice

In noting contemporary neglect of Mill\u27s work on fallacy, Hansen and Pinto say that his account is tied more closely to scientific methodology than to problems of public discourse and everyday argumentation. This paper re-examines Mill\u27s fallacies from a rhetorical perspective, assessing the extent to which his examples—drawn from the domain of popular superstition, science, philosophy, and public discussion—fits his theoretical structure. In articulating the relationship between Mill\u27s philosophical assumptions and the discursive practices of the fields from which he draws his examples, it will suggest the ambiguities in Mill\u27s mentalistic, rationalistic, inductivist approach and the inescapable rhetoricity of his examples

Spacetimeunconscious

This article argues for an understanding of material geographies as invested with an unconscious dimension. I put forward the notion of spacetimeunconscious not as an inverse, double, or ‘other’ to Karen Barad's concept of spacetimematter, but as a supplement. Manifesting the spacetimeunconscious through the technique of montage, I draw together a range of phenomena, from the icing of water and the flashing of lightning to the awakenings of traumatised and displaced subjects. Across these juxtaposed parts, I argue that the unfolding of space and time responds to the enigmatic, irreducible message of the unconscious in the real. Spacetimeunconscious arrives as the ambassador of an unknown knowledge remembered for – or in the place of – a forgetful substance: water, dreamer, or electron. In an echo of the analytic method, I use montage to create generative connections, discontinuities, and instabilities between events, poetry, literature, and film, in the interstices of which the spacetimeunconscious may make an appearance

(Re)birthing the maternal

The aim of this essay is to explore the political and ethical potential of (re)birthing through Barad’s conceptualisation of transmateriality. This article puts Barad’s thought on entanglement, emergence, and responsibility into conversation with other work in feminist philosophy and psychoanalysis that has grappled with questions of the maternal, birthing, and ethics. On the one hand, this encounter suggests that there are other ways of posing questions of separation, responsibility, and power through the maternal that might challenge aspects of Barad’s telling. But at the same time, by bringing Barad’s thought into these conversations, I show how Barad’s transpositions of (re)birthing have the potential to radically re-open and trans*figure feminist ethics and politics via a more dispersed, immoderate, and ultimately queer perspective on how the ethics that inheres in the coming into (non)being of the world

Give Iowa Trees Due Credit

Iowa is too often thought of by persons Outside the State only as a flat open prairie. Even the Iowa citizens have rarely stopped to sum up the large value of Iowa trees. The attitude that all forest land is worthless can be understood for the man who alone cleared his first small fields from virgin hardwood timber, or assisted his neighbors in log rolling bees to rid the land in what ever manner they might of trees. Today however it is different, and Iowa trees are not to be discredited

Towards a post-mathematical topology

This paper aims to bring clarity to the term topology as it has been deployed in human geography. We summarize the insights that geographers have garnered from thinking topologically about space and power. We find that many deployments of topology both overstretch topology’s conceptual merit and limit its insights for spatial thinking. We show how topology, with its structuralist and modernist baggage, requires some theoretical reworking to be put to work by poststructuralist geographers. Our purpose is not to consolidate a specific topological approach for geographers, but to call for an ongoing consideration of what topology offers poststructuralist spatial theories

Undoing mastery: With ambivalence?

In this commentary, we respond to Derek Ruez and Daniel Cockayne’s article ‘Feeling Otherwise: Ambivalent Affects and the Politics of Critique in Geography’. We do so by picking up ambivalence—or more precisely, ambivalence about ambivalence—as a tool with which Ruez and Cockayne leave us. We find this tool somewhat difficult to grasp, but we understand this as part of its design. Ambivalence undoes the subject’s mastery. In doing so, we find that an airing of ambivalence gives other kinds of entangled, indeterminate, and unknowing relations room to breathe

Southern Iowa tillage results

The McNay Memorial Research Farm near Chariton is located in the south-central Iowa agroclimatic zone and presents several unique challenges for farmers in that area. The McNay Research Farm is characterized by a series of irregular-shaped upland flats, flanked by gentle-to-steep slopes. The upland flats constitute about 20 percent of the land area

The space of encounter and the making of difference: The entangled lives of Alevi and Sunni neighbours in Turkey

The concept of encounter has long been central to a cosmopolitan ethos in which coming together in urban public space is expected to yield tolerance and pluralism. More recently scholars have reworked this concept to account for not only what is potentially transformative in encounters but also how encounters are conditioned by and productive of relations of power and inequality. Our study contributes to this reworking, and to feminist critiques of space and politics, by centring the spatiality of encounter in the entanglement of neighbours. Drawing on our focus group research (2013–2016) with Alevis and Sunnis in Istanbul and Malatya, we argue that difficult questions of difference, responsibility, and power come to the fore in neighbour relations. While our study underlines how Sunni supremacism and Alevi precarity are constituted in the everyday lives of neighbours, we also find that there is a transformational potential in these encounters that is not fully (re)absorbed into structures of Alevi–Sunni difference. We argue that, across the blurry boundaries of home and neighbourhood spaces, the unbidden intimacies of living in proximity (the drift of smells and sounds, the lines of sight that connect balconies and windows, the presence of neighbours at the thresholds and in the spaces of each other's homes) mean that encounters between neighbours both fuel and trouble the marking out of what is shared and what is separate, what is tolerable and what crosses a line. Our study thereby advances an understanding of the space of encounter, the making of difference, and the political and ethical significance of this entanglement

Potential for Electropositive Metal to Reduce the Interactions of Atlantic Sturgeon with Fishing Gear

Atlantic sturgeon (Acipenser oxyrhynchus) populations have been declared either endangered or threatened under the U.S. Endangered Species Act. Effective measures to repel sturgeon from fishing gear would be beneficial to both fish and fishers because they could reduce both fishery‐associated mortality and the need for seasonal and area closures of specific fisheries. Some chondrostean fishes (e.g., sturgeons and paddlefishes) can detect weak electric field gradients (possibly as low as 5 Μv/cm) due to arrays of electroreceptors (ampullae of Lorenzini) on their snout and gill covers. Weak electric fields, such as those produced by electropositive metals (typically mixtures of the lanthanide elements), could therefore potentially be used as a deterrent. To test this idea, we recorded the behavioral responses of juvenile Atlantic sturgeon (31–43 cm fork length) to electropositive metal (primarily a mixture of the lanthanide elements neodymium and praseodymium) both in the presence and absence of food stimuli. Trials were conducted in an approximately 2.5 m diameter × 0.3 m deep tank, and fish behaviors were recorded with an overhead digital video camera. Video records were subsequently digitized (x, y coordinate system), the distance between the fish and the electropositive metal calculated, and data summarized by compiling frequency distributions with 5‐cm bins. Juvenile sturgeon showed clear avoidance of electropositive metal but only when food was present. On the basis of our results, we conclude that the electropositive metals, or other sources of weak electric fields, may eventually be used to reduce the interactions of Atlantic sturgeon with fishing gear, but further investigation is needed. El Potencial del Metal Electropositivo para Reducir las Interacciones del Esturión Atlántico con Instrumentos de Pesca Bouyoucos, Bushnell & Brill 13–003 Resumen Las poblaciones del esturión atlántico ( Acipenser oxyrhynchus ) han sido declaradas como en peligro o amenazadas bajo el Acta de Especies en Peligro de los Estados Unidos. Las medidas efectivas para repeler a los esturiones de los instrumentos de pesca serían benéficas para los peces y los pescadores ya que podrían reducir la mortalidad asociada a la pesca y la necesidad de los cierres temporales y de área de pesquerías específicas. Algunos peces chondrosteos (p. ej.: esturiones y peces espátula) pueden detectar gradientes débiles de campos eléctricos (posiblemente tan bajos como 5 μV cm −1 ) debido a grupos de electroreceptores (ámpulas de Lorenzini) en su hocico y opérculos. Los campos eléctricos débiles, como aquellos producidos por metales electropositivos (comúnmente mezcla de elementos lantánidos), podrían entonces ser usados potencialmente como un disuasivo. Para probar esta idea, filmamos las respuestas conductuales de esturiones juveniles (31 – 43 cm de largo) a metales electropositivos (principalmente una mezcla de los elementos lantánidos neodimio y praseodimio) tanto en la presencia como en la ausencia de estímulos de alimento. Las pruebas se realizaron en un tanque de ≈ 2.5 metros de diámetro x 0.3 m de profundidad, y las conductas de los peces se filmaron con una cámara digital de video colocada sobre el tanque. Las filmaciones después se digitaron (sistema de coordenadas x, y), se calculó la distancia entre los peces y el metal electropositivo y se resumió la información al compilar las distribuciones de la frecuencia con contenedores de 5 cm. Los esturiones juveniles mostraron clara evitación del metal electropositivo pero sólo cuando el alimento estaba presente. Basándonos en nuestros resultados, concluimos que los metales electropositivos, u otras fuentes de campos eléctricos débiles, puede ser usada eventualmente para reducir las interacciones del esturión atlántico con los instrumentos de pesca, pero es necesario llevar a cabo más investigaciones.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102646/1/cobi12200.pd