Fish life histories in a warming climate: a mechanistic basis of change and a community context

Body size dependent interactions structure food webs, and these are changing with climate warming. We cannot yet predict how warming affects many aspects of life history evolution and species ecology, despite a longstanding interest in the structuring effects of temperature and body size in food webs. This is in part due to not recognizing the temperature dependence two aspects, namely that 1) withinspecies differences govern species interactions and 2) processes of adaptation depend on body size. In this thesis, I assess how body size dependent effects of temperature govern such interactions and processes using theoretical models of individual growth and reproduction. First, I study effects of warming on the energy allocation trade-off between somatic growth and energy reserves and find that warming favours allocation to reserves and reproduction through increasing importance of early life history processes. Specifically, failing to adapt to warming winters compromises viability of population through juvenile mortality. Second, I study how effects of warming on consumer-resource systems depend on energy allocation strategies. Here, energy allocation can modulate temperature dependent competition for food between stages, but competition mediated by diet is the main determinant of effects of warming. Last, I show how effects of warming affect the feedback mechanism of stage dependent competition and predation on interacting species and thus prevent adults from cultivating a low competition environment for their young. I conclude that linking underlying individual body size dependent physiological responses to warming to effects in population and communities provides novel mechanistic understanding of adaptation and food web processes. While these mechanistic predictions form a basis for, and require, empirical tests, I propose that diversity and function of aquatic food webs are at stake

Persistence of \u3cem\u3eMucor Miehei\u3c/em\u3e Protease in Cheddar Cheese and Pasteurized Whey and its Effect on Sterile Milk Products

Whey from a commercial cheese plant, taken at draining on five separate days, from cheese made with a Mucor miehei coagulant was cooled within 1 h to 4 C. Portions were adjusted from pH 4.2 to 6.4 at .2 pH intervals and subjected to HTST pasteurization at 73.9, 76.6, and 79.5 C for 25 sec. Milk clotting activity in whey was determined before and after pasteurization. Resistance to heat in-activation increased with decreasing pH. All measurable activity was destroyed above pH 5.4 by pasteurization at 79.5 C, above pH 5.8 at 76.6 C and above pH 6.0 at 73.9 C. Milk clotting activity in Cheddar cheese mad with Mucor miehei remained unchanged for 26 weeks. Four commercial sterile liquid-milk-based consisting of infant formula, concentrated infant formula, nutritionally complete food, and diet food was aseptically inoculated with sterile Mucor miehei protease solutions to concentrations ranging from 5 x 10-3 to 1 x 10-7 chymosin units/ml of product. The samples were stored at 30 C. After 20 weeks there was no change in the nutritionally complete food. The diet food showed slight whey separation and thickening at 1 x 10-4 CU/ml and coagulation at higher concentrations. The infant formula showed definite whey separation and thickening at 1 x 10-4 CU/ml and coagulation and higher concentrations. The concentrated infant formula showed visible thickening at 1 x 10-3 CU/ml and coagulation at higher concentrations

Sea surface temperature changes in the southern California borderlands during the last glacial-interglacial cycle

A variety of evidence suggests that average sea surface temperatures (SSTs) during the last glacial maximum in the California Borderlands region were significantly colder than during the Holocene. Planktonic foraminiferal δ18O evidence and average SST estimates derived by the modern analog technique indicate that temperatures were 6°-10°C cooler during the last glacial relative to the present. The glacial plankton assemblage is dominated by the planktonic foraminifer Neogloboquadrina pachyderma (sinistral coiling) and the coccolith Coccolithus pelagicus, both of which are currently restricted to subpolar regions of the North Pacific. The glacial-interglacial average SST change determined in this study is considerably larger than the 2°C change estimated by Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) [1981]. We propose that a strengthened California Current flow was associated with the advance of subpolar surface waters into the Borderlands region during the last glacial

Deepwater expansion and enhanced remineralization in the eastern equatorial Pacific during the last glacial maximum

Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography and Paleoclimatology 33 (2018): 563-578, doi:10.1029/2017PA003221.Published estimates of the radiocarbon content of middepth waters suggest a decrease in ventilation in multiple locations during the last glacial maximum (LGM; 24.0–18.1 ka). Reduced glacial ventilation would have allowed respired carbon to accumulate in those waters. A subsequent deglacial release of this respired carbon reservoir to the atmosphere could then account for the observed increases in atmospheric CO2 and decline in atmospheric radiocarbon content. However, age model error and a release of 14C‐depleted mantle carbon have also been cited as possible explanations for the observed middepth radiocarbon depletions, calling into question the deep ocean's role in storing respired carbon during the LGM. Joint measurements of benthic foraminiferal carbon isotope values (δ13C) and cadmium/calcium (Cd/Ca) ratios provide a method for isolating the air‐sea component of a water mass from changes in remineralization. Here we use benthic foraminiferal δ13C and Cd/Ca records from the eastern equatorial Pacific to constrain changes in remineralization and water‐mass mixing over the last glacial‐interglacial transition. These records are complemented with elemental measurements of the authigenic coatings of foraminifera to monitor postdepositional changes in bottom water properties. Our results suggest an increase of deep waters at midwater depths consistent with a shoaling of the boundary between the upper and lower branches of Southern Ocean overturning circulation. Additionally, our records demonstrate increased organic matter remineralization in middepth waters during the LGM, suggesting that respired carbon did accumulate in middepth waters under periods of reduced ventilation.National Science foundation Grant Number: OCE‐09563682018-11-1

Safe use of perampanel in a carrier of variegate porphyria

Objectives. Treatment of chronic epilepsy in acute porphyrias may be difficult because many antiepileptic drugs can cause activation of clinically-latent conditions. Methods. A 44 year-old lady with drug-resistant chronic epilepsy and a previous genetic diagnosis of variegate porphyria was referred to our epilepsy centre. We started her on perampanel, a structurally novel selective non-competitive AMPA receptor antagonist recently approved for the treatment of partial and secondarily generalized seizures in humans. There are no previous reports about the outcome of exposure to perampanel of carriers of acute porphyria. Results. Perampanel was assessed in silico to be probably not porphyrogenic. Administration of the drug up to 4 mg/day did not lead to elevation of urinary porphobilinogen excretion, nor to any symptoms of acute porphyria after more than 23 months of treatment. Conclusions. Perampanel up to 4 mg/day was tolerated in long-term therapy in this carrier of protoporphyrinogen oxidase deficiency. However, since perampanel is a weak inducer of cytochrome P450 enzymes, vigilance should be maintained for clinical and biochemical signs of activation of acute porphyria when used in a carrier of acute porphyria

In Memory of Michael Strayer

Michael Paul Strayer, a senior veterinary medicine student at Iowa State University, died on November 10, 1991 of a cocaine overdose. Michael was born on September 14, 1960 to Dr. and Mrs. Paul Strayer in Cresco, IA. He moved from Waterloo 10 years ago to Ames and was a student at Iowa State University. He married Holly Hunt on August 24, 1991, in Nevada, IA

Restructuring and Forgiveness in Financial Crises C: The Swedish Banking Crisis of 1990-94

In the Spring of 1992, the Swedish government faced a dilemma. The country was in the midst of an economic downturn stemming from the collapse of asset prices (especially in real estate) that had spiked as a result of a credit boom that followed the deregulation of the Swedish banking system in the mid-1980s. Initially the impact of the downturn on the country’s banks had seemed to be limited to a small number of specific firms that the government moved to assist on an ad hoc basis in 1991. However, evidence was mounting that the banking crisis was reaching a systemic level. Guided by such principles as the need for broad political consensus, prompt action, transparency, and the imposition of strict conditions including shareholder losses in exchange for support, the Swedish government crafted a response centered around a blanket guarantee of all bank liabilities, an immediate recognition of all bank losses, support for banks that was based on each bank’s specific financial condition and prospects, and the use of asset management companies to resolve the troubled assets of struggling banks. This approach, coupled with an improving economy, helped restore the Swedish banking system to profitability by 1995. While the fact that the Swedish banking sector of the early 1990s was much less complex than most major financial systems today cautions against drawing any firm conclusion about the appropriateness of deploying specific Swedish policy responses in new crises, the various principles that guided the Swedish response could well be of interest in addressing future systemic events

Effects of Warming on Intraguild Predator Communities with Ontogenetic Diet Shifts

Species interactions mediate how warming affects community composition via individual growth and population size structure. While predictions on how warming affects composition of size- or stage-structured communities have so far focused on linear (food chain) communities, mixed competition-predation interactions, such as intraguild predation, are common. Intraguild predation often results from changes in diet over ontogeny ("ontogenetic diet shifts") and strongly affects community composition and dynamics. Here, we study how warming affects a community of intraguild predators with ontogenetic diet shifts, consumers, and shared prey by analyzing a stage-structured bioenergetics multispecies model with temperature- and body size-dependent individual-level rates. We find that warming can strengthen competition and decrease predation, leading to a loss of a cultivation mechanism (the feedback between predation on and competition with consumers exerted by predators) and ultimately predator collapse. Furthermore, we show that the effect of warming on community composition depends on the extent of the ontogenetic diet shift and that warming can cause a sequence of community reconfigurations in species with partial diet shifts. Our findings contrast previous predictions concerning individual growth of predators and the mechanisms behind predator loss in warmer environments and highlight how feedbacks between temperature and intraspecific size structure are important for understanding such effects on community composition

Optimal energy allocation trade-off driven by size-dependent physiological and demographic responses to warming

Body size-dependent physiological effects of temperature influence individual growth, reproduction, and survival, which govern animal population responses to global warming. Considerable knowledge has been established on how such effects can affect population growth and size structure, but less is known of their potential role in temperature-driven adaptation in life-history traits. In this study, we ask how warming affects the optimal allocation of energy between growth and reproduction and disentangle the underlying fitness trade-offs. To this end, we develop a novel dynamic energy budget integral projection model (DEB-IPM), linking individuals' size- and temperature-dependent consumption and maintenance via somatic growth, reproduction, and size-dependent energy allocation to emergent population responses. At the population level, we calculate the long-term population growth rate (fitness) and stable size structure emerging from demographic processes. Applying the model to an example of pike (Esox lucius), we find that optimal energy allocation to growth decreases with warming. Furthermore, we demonstrate how growth, fecundity, and survival contribute to this change in optimal allocation. Higher energy allocation to somatic growth at low temperatures increases fitness through survival of small individuals and through the reproduction of larger individuals. In contrast, at high temperatures, increased allocation to reproduction is favored because warming induces faster somatic growth of small individuals and increased fecundity but reduced growth and higher mortality of larger individuals. Reduced optimum allocation to growth leads to further reductions in body size and an increasingly truncated population size structure with warming. Our study demonstrates how, by incorporating general physiological mechanisms driving the temperature dependence of life-history traits, the DEB-IPM framework is useful for investigating the adaptation of size-structured organisms to warming