Showing papers by "Jonathan W. Moore published in 2015"

Portfolio conservation of metapopulations under climate change

Abstract: Climate change is likely to lead to increasing population variability and extinction risk. Theoretically, greater population diversity should buffer against rising climate variability, and this theory is often invoked as a reason for greater conservation. However, this has rarely been quantified. Here we show how a portfolio approach to managing population diversity can inform metapopulation conservation priorities in a changing world. We develop a salmon metapopulation model in which productivity is driven by spatially distributed thermal tolerance and patterns of short- and long-term climate change. We then implement spatial conservation scenarios that control population carrying capacities and evaluate the metapopulation portfolios as a financial manager might: along axes of conservation risk and return. We show that preserving a diversity of thermal tolerances minimizes risk, given environmental stochasticity, and ensures persistence, given long-term environmental change. When the thermal tolerances of populations are unknown, doubling the number of populations conserved may nearly halve expected metapopulation variability. However, this reduction in variability can come at the expense of long-term persistence if climate change increasingly restricts available habitat, forcing ecological managers to balance society's desire for short-term stability and long-term viability. Our findings suggest the importance of conserving the processes that promote thermal-tolerance diversity, such as genetic diversity, habitat heterogeneity, and natural disturbance regimes, and demonstrate that diverse natural portfolios may be critical for metapopulation conservation in the face of increasing climate variability and change.

Emergent stability in a large, free‐flowing watershed

Abstract: 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.

Juvenile salmon usage of the Skeena River estuary.

Abstract: Migratory salmon transit estuary habitats on their way out to the ocean but this phase of their life cycle is more poorly understood than other phases. The estuaries of large river systems in particular may support many populations and several species of salmon that originate from throughout the upstream river. The Skeena River of British Columbia, Canada, is a large river system with high salmon population- and species-level diversity. The estuary of the Skeena River is under pressure from industrial development, with two gas liquefaction terminals and a potash loading facility in various stages of environmental review processes, providing motivation for understanding the usage of the estuary by juvenile salmon. We conducted a juvenile salmonid sampling program throughout the Skeena River estuary in 2007 and 2013 to investigate the spatial and temporal distribution of different species and populations of salmon. We captured six species of juvenile anadromous salmonids throughout the estuary in both years, and found that areas proposed for development support some of the highest abundances of some species of salmon. Specifically, the highest abundances of sockeye (both years), Chinook in 2007, and coho salmon in 2013 were captured in areas proposed for development. For example, juvenile sockeye salmon were 2–8 times more abundant in the proposed development areas. Genetic stock assignment demonstrated that the Chinook salmon and most of the sockeye salmon that were captured originated from throughout the Skeena watershed, while some sockeye salmon came from the Nass, Stikine, Southeast Alaska, and coastal systems on the northern and central coasts of British Columbia. These fish support extensive commercial, recreational, and First Nations fisheries throughout the Skeena River and beyond. Our results demonstrate that estuary habitats integrate species and population diversity of salmon, and that if proposed development negatively affects the salmon populations that use the estuary, then numerous fisheries would also be negatively affected.

Bidirectional connectivity in rivers and implications for watershed stability and management1

Abstract: River networks are connected in both upstream and downstream directions on large spatial scales by movement of water, materials, and animals. Here I examine the implications of these linkages for the stability, productivity, and management of watersheds and their migratory fishes. I use simple simulations of watershed alteration to illustrate that degradation can erode the productivity and stability of both upstream and downstream fisheries. Through analysis of an existing global dataset on rivers, I found that larger rivers tend to be more fragmented than smaller rivers. I offer three challenges and opportunities for the future management of watersheds. First, given that human impacts can spread up and down rivers, there is a need to align the scales of impact assessments with the natural scale of river systems. Second, free-flowing rivers naturally dampen variability; thus, the conservation of connectivity, habitat, and biodiversity represents a key opportunity to sustain the processes that confer stabi...

Selling First Nations down the river

Abstract: Oil and gas interests and the government recently offered a First Nation in the Skeena River estuary (BC, Canada) $1 billion to consent to construction of a controversial terminal to load fossil fuels onto tankers ([ 1 ][1]). The proposal highlights a troubling blind spot in Canada's environmental

Implications of spatial contraction for density dependence and conservation in a depressed population of anadromous fish

Abstract: Changes in density-independent mortality can alter the spatial extent of populations through patch extinction and colonization, and spatial contraction may alter population productivity and compens...

Assessing the Relationship between Gulls Larus spp. and Pacific Salmon in Central California Using Radiotelemetry

Abstract: Predation by marine birds has resulted in substantial losses to runs of Pacific salmon Oncorhynchus spp., in some cases necessitating management action. Recovery of PIT tags on a seabird breeding colony (Ano Nuevo Island) indicated that western gulls Larus occidentalis prey upon federally listed Coho Salmon Oncorhynchus kisutch and steelhead O. mykiss in central California. Whereas salmonid populations in central California have decreased in recent decades, the western gull population on Ano Nuevo Island has increased. We observed gulls Larus spp. within estuaries to document predation and used radiotelemetry to examine gull movement in relation to the availability of salmonids. During 2008 and 2009, observed predation events of out-migrating salmonids by gulls were rare; 21 events occurred during 338 h of observations at two estuaries. During the prehatch and chick-rearing phases of breeding, which coincided with migration of salmonids from fresh to salt water, 74% of the detections of radio-tagg...

When the Tides Don’t Turn: Floodgates and Hypoxic Zones in the Lower Fraser River, British Columbia, Canada

Abstract: Floodgates are common flood control structures in coastal river systems, which allow tributary drainage into river main stems and decrease flooding risk of land upstream of diking systems. Floodgates have been shown to impact upstream aquatic habitats and alter organismal community structures in some systems by impounding water and acting as a physical barrier to migratory species; their impacts on water quality have been less well described. This study investigated water quality in tidal creeks with and without floodgates on the lower Fraser River, British Columbia, Canada. There are an estimated 500 floodgates in this region. Water quality measurements were taken upstream and downstream at three floodgate sites and three reference sites across a 10-day period in July/August. The average dissolved oxygen (DO) concentration upstream of floodgates was 2.47 mg/L and fell as low as 0.08 mg/L, which was significantly lower than the comparable region of reference sites (8.41 mg/L) during this sampling period. In contrast, the average DO concentration downstream of floodgates was 7.38 mg/L and in reference sites 8.35 mg/L. All DO concentration measurements upstream of floodgates in July and August fell below the 6-mg/L minimum set by the Canadian Council of Ministers of the Environment. These hypoxic zones extended at least 100 m upstream of floodgates. Thus, floodgates may be facilitating the occurrence of local hypoxic zones in summer months in these locations. Floodgate-induced hypoxia may not only cause local exclusion of sensitive native fishes but may also act as a chemical barrier that decreases connectivity among aquatic systems. Understanding these environmental impacts associated with floodgates can inform floodgate design and post-installation management, which is an increasingly important issue as coastal municipalities across the world deal with aging floodgate infrastructure and sea level rise.

Fish assemblages and barriers in an urban stream network

Abstract: Stream networks are vulnerable to fragmentation. Anthropogenic structures, such as dams and culverts, can isolate stream branches, potentially interrupting longitudinal gradients of fish distribution. The effect of single barriers is well documented, but the effect of multiple barriers in small streams is not as well characterized. We used a landscape approach and spatially continuous sampling across 2 y to examine the influence of anthropogenic structures on fish distributions in an urban stream network. After accounting for spatial autocorrelation, we found higher Coastal Cutthroat Trout (Oncorhynchus clarki clarki) and lower Prickly Sculpin (Cottus asper) densities at locations up- than downstream of multiple culverts. Culverts had species- and year-specific stepwise effects that overrode fish distribution patterns attributable to environmental gradients. Prickly Sculpin exhibited strong spatial autocorrelation in both years, whereas Coho Salmon (Oncorhynchus kisutch) had negligible spatial aut...