Sockeye salmon that spawn downstream of rearing lakes are an important example of the challenges faced by organisms with complex life histories requiring connectivity in aquatic habitat complexes. ...Specifically, newly emerged juvenile sockeye salmon must migrate upstream, against the flow of water, if they are to reach lake rearing habitat. Here, we examine the spatial and temporal dynamics of the water velocity landscape and juvenile sockeye salmon movement and condition at increasing distances downstream from the lake outlet of an important sockeye salmon system, the Babine Lake of British Columbia, one of Canada’s largest and most important sockeye salmon rearing lakes. The results of this study indicate that (i) there were seasonal and spatial patterns of water velocities that exceed the ability of juveniles to swim upstream to lake rearing habitat, (ii) higher water discharge was associated with more velocity barriers and potentially with less upstream movement of juveniles, and (iii) juveniles rearing in the lake obtained larger sizes (30% longer and 150% heavier) than those in downstream river habitats. Multiple processes that may be influencing these patterns could include more abundant food resources, lower metabolic demands, or size-selective immigration, emigration, or mortality among habitats. Years and seasons with high discharge may temporarily create one-way, downstream transport routes at lake outlets. Long-term changes in hydrology, perhaps driven by climate variability or land-use change, may control the degree to which lake outlets function as bidirectional travel corridors or one-way travel routes for young sockeye salmon.
Interpopulation variation in dynamics can buffer species against environmental change. We compared population synchrony in a group of threatened Chinook salmon in the highly impacted Snake River ...basin (Oregon, Washington, Idaho) to that in the sockeye salmon stock complex of less impact Bristol Bay (Alaska). Over the last 40 years, >90% of populations in the Snake River basin became more synchronized with one another. However, over that period, sockeye populations from Alaska did not exhibit systemic changes in synchrony. Coincident with increasing Snake River population synchrony, there was an increase in hatchery propagation and the number of large dams, potentially homogenizing habitats and populations. A simulation using economic portfolio theory revealed that synchronization of Snake River salmon decreased risk‐adjusted portfolio performance (the ratio of portfolio productivity to variance) and decreased benefits of population richness. Improving portfolio performance for exploited species, especially given future environmental change, requires protecting a diverse range of populations and the varied habitats upon which they depend.
Nonenzymatic glycation of tissue proteins has important implications in the development of complications of diabetes mellitus. Herein we report improved methods for the enrichment and analysis of ...glycated peptides using boronate affinity chromatography and electron-transfer dissociation mass spectrometry, respectively. The enrichment of glycated peptides was improved by replacing an off-line desalting step with an online wash of column-bound glycated peptides using 50 mM ammonium acetate, followed by elution with 100 mM acetic acid. The analysis of glycated peptides by MS/MS was improved by considering only higher charged (≥3) precursor ions during data-dependent acquisition, which increased the number of glycated peptide identifications. Similarly, the use of supplemental collisional activation after electron transfer (ETcaD) resulted in more glycated peptide identifications when the MS survey scan was acquired with enhanced resolution. Acquiring ETD-MS/MS data at a normal MS survey scan rate, in conjunction with the rejection of both 1+ and 2+ precursor ions, increased the number of identified glycated peptides relative to ETcaD or the enhanced MS survey scan rate. Finally, an evaluation of trypsin, Arg-C, and Lys-C showed that tryptic digestion of glycated proteins was comparable to digestion with Lys-C and that both were better than Arg-C in terms of the number of glycated peptides and corresponding glycated proteins identified by LC−MS/MS.
Estuary food webs support many fishes whose habitat preferences and population dynamics may be controlled by prey abundance and distribution. Yet the identity and dynamics of important estuarine prey ...of many species are either unknown or highly variable between regions. As anthropogenic development in estuaries increases, so does the need to understand how these environments may be supporting economically, culturally, and ecologically important fishes. Here, we examine how important estuary fishes integrate their prey across the seascape and what may influence prey dynamics. Specifically, we surveyed juvenile coho salmon Oncorhynchus kisutch, juvenile sockeye salmon O. nerka, Pacific herring Clupea pallasii, and surf smelt Hypomesus pretiosus diets along with zooplankton abundance in the estuary of the Skeena River (British Columbia, Canada) at a relatively fine scale. We found diets were highly variable, even within a species, but 1 or 2 prey composed most diet contents per species. Juvenile coho salmon primarily consumed terrestrial insects and larval fish, whereas sockeye salmon primarily consumed harpacticoid copepods. In contrast, small pelagic fish (Pacific herring and surf smelt) primarily consumed calanoid copepods, which were the most abundant prey in the environment. We found that certain prey groups were correlated with biophysical factors. For example, calanoid copepod abundance was positively correlated with salinity, whereas harpacticoid copepod abundance was highest over eelgrass sites. Identifying key prey species and how they distribute within the estuary seascape is an integral link in understanding the food-web foundation of fish habitat use in areas under pressure from anthropogenic development.
Current investment in conservation is insufficient to adequately protect and recover all ecosystems and species. The challenge of allocating limited funds is acute for Pacific salmon Oncorhynchus ...spp. in Canada, which lack a strategic approach to ensure that resources are spent on actions most likely to cost‐effectively recover diminished populations.
We applied the Priority Threat Management framework to prioritize strategies most likely to maximize the number of thriving Pacific salmon populations on the Central Coast of British Columbia, Canada. These included 79 genetically, ecologically and spatially distinct population groups called conservation units (CUs) for five salmon species. This region has high salmon biodiversity and spans the territories of four First Nations: the Heiltsuk, Nuxalk, Kitasoo/Xai'xais and Wuikinuxv.
Using structured expert elicitation of Indigenous and other experts, we quantified the estimated benefits, costs and feasibility of implementing 10 strategies. Under a business‐as‐usual scenario (i.e. no additional investments in salmon conservation or management), experts predicted that only one in four CUs would have >50% chance of achieving a thriving status within 20 years. Limiting future industrial development in salmon habitats, which was predicted to safeguard CUs from future declines, was identified as the most cost‐effective strategy. Investment in three strategies: (a) removal of artificial barriers to fish migration, (b) watershed protection and (c) stream restoration—at 11.3M CAD per year—was predicted to result in nearly half (34 of 79) of the CUs having a >60% chance of meeting the conservation objective.
If all conservation strategies were implemented, experts estimated a >50% probability of achieving a thriving status for 78 of 79 CUs, at an annual cost of 17.3M CAD. However, even with the implementation of all strategies, most sockeye salmon CUs were unlikely to achieve higher probability targets of reaching the objective.
Policy implications. We illustrate how Priority Threat Management can incorporate the perspectives and expertise of Indigenous peoples and other experts to prioritize conservation strategies based on their cost, benefit and feasibility. Implementation of this framework can help safeguard and recover Pacific salmon in Canada, and could also be used to prioritize actions for other conservation issues globally.
We illustrate how Priority Threat Management can incorporate the perspectives and expertise of Indigenous peoples and other experts to prioritize conservation strategies based on their cost, benefit and feasibility. Implementation of this framework can help safeguard and recover Pacific salmon in Canada, and could also be used to prioritize actions for other conservation issues globally.
Glacier Retreat and Pacific Salmon PITMAN, KARA J.; MOORE, JONATHAN W.; SLOAT, MATTHEW R. ...
Bioscience,
03/2020, Volume:
70, Issue:
3
Journal Article
Peer reviewed
Open access
Glaciers have shaped past and present habitats for Pacific salmon (Oncorhynchus spp.) in North America. During the last glacial maximum, approximately 45% of the current North American range of ...Pacific salmon was covered in ice. Currently, most salmon habitat occurs in watersheds in which glacier ice is present and retreating. This synthesis examines the multiple ways that glacier retreat can influence aquatic ecosystems through the lens of Pacific salmon life cycles. We predict that the coming decades will result in areas in which salmon populations will be challenged by diminished water flows and elevated water temperatures, areas in which salmon productivity will be enhanced as downstream habitat suitability increases, and areas in which new river and lake habitat will be formed that can be colonized by anadromous salmon. Effective conservation and management of salmon habitat and populations should consider the impacts of glacier retreat and other sources of ecosystem change.
Habitats along migratory routes may provide key resources for migratory species (e.g. stopover habitat). For example, migratory juvenile salmon transit through estuaries on their way from freshwaters ...out to the ocean, but they may also reside and feed in these habitats. Here we examined the amount of time that juvenile salmon feed and reside in the estuary of the Skeena River (British Columbia, Canada), the second-largest salmon-bearing watershed in Canada. We implemented a novel application of stable isotopes of sulfur, carbon, and nitrogen as clocks to estimate the days since estuary entry. Salmon estuary residency varied across species; 25% of individuals spent at least 33, 22, 30, and 5 d in the estuary for Chinook Oncorhynchus tshawytscha, coho O. kisutch, pink O. gorbuscha, and sockeye salmon O. nerka, respectively. Larger pink and Chinook salmon resided in the estuary for longer durations, growing at an estimated 0.2 and 0.5 mm d−1, respectively, evidence that estuary residency provides growth opportunities. A negative relationship between size and estuary residency in coho salmon suggests the potential existence of an estuary fry life history. Genetic stock assignment indicated that different populations of sockeye salmon may reside in the estuary for different amounts of time. Collectively, these results reveal that estuaries can represent stopover habitats for salmon, and that the extent varies across salmon species and populations. These data address a knowledge gap in assessment of environmental risks of proposed industrial developments. This study indicates the importance of considering the fundamental nature of habitats through which migratory species move.
We present high-resolution, high-cadence observations of six, fine-scale, on-disk jet-like events observed by the High-resolution Coronal Imager 2.1 (Hi-C 2.1) during its sounding-rocket flight. We ...combine the Hi-C 2.1 images with images from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and the Interface Region Imaging Spectrograph (IRIS), and investigate each event's magnetic setting with co-aligned line-of-sight magnetograms from the SDO/Helioseismic and Magnetic Imager (HMI). We find that (i) all six events are jetlet-like (having apparent properties of jetlets), (ii) all six are rooted at edges of magnetic network lanes, (iii) four of the jetlet-like events stem from sites of flux cancelation between majority-polarity network flux and merging minority-polarity flux, and (iv) four of the jetlet-like events show brightenings at their bases reminiscent of the base brightenings in coronal jets. The average spire length of the six jetlet-like events (9000 3000 km) is three times shorter than that for IRIS jetlets (27,000 8000 km). While not ruling out other generation mechanisms, the observations suggest that at least four of these events may be miniature versions of both larger-scale coronal jets that are driven by minifilament eruptions and still-larger-scale solar eruptions that are driven by filament eruptions. Therefore, we propose that our Hi-C events are driven by the eruption of a tiny sheared-field flux rope, and that the flux rope field is built and triggered to erupt by flux cancelation.
Emergent stability in a large, free-flowing watershed Moore, Jonathan W; Beakes, Michael P; Nesbitt, Holly K ...
Ecology (Durham),
2015-February, 20150201, February 2015, 2015-Feb, 2015-02-00, Volume:
96, Issue:
2
Journal Article
Peer reviewed
Open access
While it is widely recognized that financial stock portfolios can be stabilized through diverse investments, it is also possible that certain habitats can function as natural portfolios that ...stabilize ecosystem processes. Here we propose and examine the hypothesis that free-flowing river networks act as such portfolios and confer stability through their integration of upstream geological, hydrological, and biological diversity. We compiled a spatially (142 sites) and temporally (1980-present) extensive data set on fisheries, water flows, and temperatures, from sites within one of the largest watersheds in the world that remains without dams on its mainstem, the Fraser River, British Columbia, Canada. We found that larger catchments had more stable fisheries catches, water flows, and water temperatures than smaller catchments. These data provide evidence that free-flowing river networks function as hierarchically nested portfolios with stability as an emergent property. Thus, free-flowing river networks can represent a natural system for buffering variation and extreme events.
Conservation scientists rarely have the information required to understand changes in abundance over more than a few decades, even for important species like Pacific salmon. Such lack of historical ...information can underestimate the magnitude of decline for depressed populations. We applied genetic tools to a unique collection of 100‐year‐old salmon scales to reveal declines of 56%–99% in wild sockeye populations across Canada's second largest salmon watershed, the Skeena River. These analyses reveal century‐long declines that are much greater than those based on modern era abundance data, which suggested that only 7 of 13 populations declined over the last five decades. Populations of larger‐bodied fish have declined the most in abundance, likely because of size‐selective commercial fisheries. Our findings illustrate how a deep historical perspective can expand our understanding of past abundances to a time before species incurred significant losses from fishing, and help inform conservation for diminished populations.
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