Bottom-up and top-down processes affecting marine survival of salmon in the Salish Sea

Bottom-up processes mechanistically link with top-down control of populations, and these interactions are mediated by environmental variability and human-induced changes in land and water use. Size-selective mortality can be a significant force regulating recruitment of salmon and may be imposed at different life stages and habitats for different species, stocks, or life history types. The first months of marine growth are commonly regarded as a critical period for growth and survival of salmon. For ESA-listed Puget Sound Chinook salmon, emergent bottom-up patterns include: 1) a critical growth period occurs when body mass increases 2-4 fold during the first month of feeding in epi-pelagic habitats within Puget Sound; 2) that growth is limited primarily by food supply, but can be exacerbated by warm temperatures in shoreline habitiats; 3) higher growth and survival correspond with higher contributions of key prey like larval crab. Piscivorous fishes exhibit size-selective predation on juvenile salmon in Puget Sound, and resident forms of Chinook salmon are capable of imposing significant mortality on subyearling Chinook in Puget Sound

Size-selective mortality and bioenergetic limitations of juvenile steelhead under different freshwater environmental constraints in the Skagit River, Washington

We used bioenergetics modeling to investigate how environmental factors affected early growth and survival in steelhead, Oncorhynchus mykiss, under different environmental constraints in tributaries to the Skagit River, Washington. Differences in early growth between the average juvenile and juveniles that survived to later stages were due to differences in feeding rates and environmental factors associated with each tributary. In Bacon Creek, feeding rates between the average juvenile and juveniles that survived to later stages were not substantially different, but low summertime prey energy density and water temperatures decreased the scope for growth in the average juvenile and juveniles that survived to later stages. In Illabot Creek, low mean annual feeding rate in the average age 1–2 juvenile decreased the summer scope for growth, and low water temperatures during fall and winter combined with low winter prey energy density caused prolonged weight loss. The average age 2–3 juvenile fed at the same rate as age 2–3 juveniles that survived to later stages in Illabot Creek, but because of lower feeding and growth during age 1–2, the average juvenile was unable to reach the size attained at age-2 and -3 by juveniles that survived to later stages. In Finney Creek, the water temperature regime was relatively extreme, but elevated annual feeding rates and summertime prey energy densities greatly increased the scope for growth in the average juvenile that survived to the adult stage, indicating that feeding rate and summertime food quality may be critical to survival in these steelhead. Early growth of steelhead in the Skagit River influences survival to smolt and adult stages, and recovery of this threatened species could be enhanced by gaining a better understanding of general factors that limit growth in the mosaic of riverine habitats that support wild steelhead

Marine Survival of Puget Sound Chinook salmon-New studies on size-selective mortality and critical growth periods

Size-selective mortality (SSM) is a significant force regulating recruitment at multiple stage during the life cycle of anadromous salmon, but the early marine life stages are consistently implicated as critical periods for growth and survival which influence SSM. The life stage(s) and habitat(s) when and where SSM is imposed can vary considerably among species, stocks, and life history strategies, and the relationship between size, growth, and condition in freshwater and marine life stages to overall life cycle survival is unclear for most stocks of salmon. Starting in Spring 2014, we will initiate a field sampling program is 4 Puget Sound watersheds that methodically tracks the timing, duration, and relative abundance of juvenile Chinook salmon at hatchery release, river outmigration (smolt traps), rearing in estuarine delta (tidal channel traps) nearshore marine (beach seines) and offshore marine habitats (purse seining and midwater trawling) of Puget Sound from April through October. The timing and relative magnitude of SSM will be determined by serial sampling of size distributions over a progression of life stages using both direct measurements of body size and back-calculated estimates from scales or otoliths. Disproportionate reductions in the contribution of smaller members to subsequent life stages, especially to adult returns, can be used to determine the timing and magnitude of SSM and identify critical periods of growth and survival. We will then diagnose which factors most affect growth during critical periods through bioenergetics modeling simulations that are linked to directed sampling of diet, growth and environmental conditions. This approach could potentially improve run forecasting and focus restoration efforts

Effects of large infrastructure on the underwater visual environment and heightened predation on salmon in the Salish Sea

Most predatory fish, marine mammals, and birds that eat salmon rely primarily on vision to feed. Natural processes and anthropogenic change affect visual conditions underwater which in turn profoundly affect the magnitude of predation risk on juvenile and adult salmon as well as forage fishes and other species in shoreline and pelagic environments. I will discuss the implications of how natural and anthropogenic changes in water transparency and artificial light pollution have significantly increased the predation threat environment for juvenile salmon in the Salish Sea and relate these to some of the major infrastructure projects in the Pacific Northwest. High levels of artificial light pollution are pervasive throughout Puget Sound and the southern portion of the Strait of Georgia. Over the past 30-40 years, increasing light pollution in Lake Washington, a useful surrogate for the greater Salish Sea, has expanded the peak twilight predation periods of juvenile salmon predators from just dusk and dawn to predation increasing throughout the night. Moreover, changing hydrology and water quality due to dams, climate, and land-water use have changed the magnitude, timing, and spatial patterns in water transparency from sediment plumes and plankton blooms. Collectively, these changes in underwater light penetration and transparency have fundamentally changed the predation environment with important implications for marine survival of salmon, functional sustainability of forage fish populations and the services they provide to the broader ecosystem

Effect of fatigue and hypohydration on gait characteristics during treadmill exercise in the heat while wearing firefighter thermal protective clothing.

This study compared the gait characteristics of individuals walking in heat while wearing firefighting equipment in fatigued and non-fatigued states. Nineteen subjects performed a 50-min treadmill protocol in a heated room while gait patterns were recorded using a digital video camcorder. Forty gait cycles were analyzed near the beginning (9 min) and at the end (39-49 min) of exercise. Spatio-temporal gait variables including step frequency, step length, swing time, stance time, cycle time and double-support time were determined. Gait variability was quantified by the standard deviation (SD) and coefficient of variation (CV) of each variable. Left-right symmetry was calculated using the symmetry index (SI) and symmetry angle (SA). Paired t-tests (alpha = 0.05) were performed to identify difference between the beginning and the end of the protocol for each measured variable. Spatio-temporal gait characteristics did not differ between the beginning and the end of exercise. Gait variability of the double-support time increased at the end as measured by both SD (P = 0.037) and CV (P = 0.030) but no change was observed for other variables. Left-right symmetry measured using either SI or SA did not differ between sessions. In summary, spatio-temporal gait characteristics and symmetry while wearing firefighting equipment are insensitive to physiological fatigue. Prolonged walking in heat while wearing firefighting equipment may increase gait variability and therefore the likelihood of a fall. Future studies are needed to confirm the potential relationship between fatigue and gait variability and to investigate the possible influence of individual variation

Reverse evolution of armor plates in the threespine stickleback.

Faced with sudden environmental changes, animals must either adapt to novel environments or go extinct. Thus, study of the mechanisms underlying rapid adaptation is crucial not only for the understanding of natural evolutionary processes but also for the understanding of human-induced evolutionary change, which is an increasingly important problem [1-8]. In the present study, we demonstrate that the frequency of completely plated threespine stickleback fish (Gasterosteus aculeatus) has increased in an urban freshwater lake (Lake Washington, Seattle, Washington) within the last 40 years. This is a dramatic example of "reverse evolution,"[9] because the general evolutionary trajectory is toward armor-plate reduction in freshwater sticklebacks [10]. On the basis of our genetic studies and simulations, we propose that the most likely cause of reverse evolution is increased selection for the completely plated morph, which we suggest could result from higher levels of trout predation after a sudden increase in water transparency during the early 1970s. Rapid evolution was facilitated by the existence of standing allelic variation in Ectodysplasin (Eda), the gene that underlies the major plate-morph locus [11]. The Lake Washington stickleback thus provides a novel example of reverse evolution, which is probably caused by a change in allele frequency at the major plate locus in response to a changing predation regime

Reducing sequencing complexity in dynamical quantum error suppression by Walsh modulation

We study dynamical error suppression from the perspective of reducing sequencing complexity, in order to facilitate efficient semi-autonomous quantum-coherent systems. With this aim, we focus on digital sequences where all interpulse time periods are integer multiples of a minimum clock period and compatibility with simple digital classical control circuitry is intrinsic, using so-called em Walsh functions as a general mathematical framework. The Walsh functions are an orthonormal set of basis functions which may be associated directly with the control propagator for a digital modulation scheme, and dynamical decoupling (DD) sequences can be derived from the locations of digital transitions therein. We characterize the suite of the resulting Walsh dynamical decoupling (WDD) sequences, and identify the number of periodic square-wave (Rademacher) functions required to generate a Walsh function as the key determinant of the error-suppressing features of the relevant WDD sequence. WDD forms a unifying theoretical framework as it includes a large variety of well-known and novel DD sequences, providing significant flexibility and performance benefits relative to basic quasi-periodic design. We also show how Walsh modulation may be employed for the protection of certain nontrivial logic gates, providing an implementation of a dynamically corrected gate. Based on these insights we identify Walsh modulation as a digital-efficient approach for physical-layer error suppression.Comment: 15 pages, 3 figure

Polymorphisms in the Taste Receptor Gene (Tas1r3) Region are Associated with Saccharin Preference in 30 Mouse Strains.

The results of recent studies suggest that the mouse Sac (saccharin preference) locus is identical to the Tas1r3 (taste receptor) gene. The goal of this study was to identify Tas1r3 sequence variants associated with saccharin preference in a large number of inbred mouse strains. Initially, we sequenced approximately 6.7 kb of the Tas1r3 gene and its flanking regions from six inbred mouse strains with high and low saccharin preference, including the strains in which the Sac alleles were described originally (C57BL/6J, Sac(b); DBA/2J, Sac(d)). Of the 89 sequence variants detected among these six strains, eight polymorphic sites were significantly associated with preferences for 1.6 mm saccharin. Next, each of these eight variant sites were genotyped in 24 additional mouse strains. Analysis of the genotype-phenotype associations in all 30 strains showed the strongest association with saccharin preference at three sites: nucleotide (nt) -791 (3 bp insertion/deletion), nt +135 (Ser45Ser), and nt +179 (Ile60Thr). We measured Tas1r3 gene expression, transcript size, and T1R3 immunoreactivity in the taste tissue of two inbred mouse strains with different Tas1r3 haplotypes and saccharin preferences. The results of these experiments suggest that the polymorphisms associated with saccharin preference do not act by blocking gene expression, changing alternative splicing, or interfering with protein translation in taste tissue. The amino acid substitution (Ile60Thr) may influence the ability of the protein to form dimers or bind sweeteners. Here, we present data for future studies directed to experimentally confirm the function of these polymorphisms and highlight some of the difficulties of identifying specific DNA sequence variants that underlie quantitative trait loci