Marine ecosystems respond to a range of habitat variability in coastal zones modified by glacial ... more Marine ecosystems respond to a range of habitat variability in coastal zones modified by glacial freshwater outflows, biophysical data were collected in three study regions that included four major glacial fjord systems around the Gulf of Alaska. A suite of geographic, oceanographic, nutrient and biological attributes were sampled at these three study regions during peak ice-melt season in summer.
region, auklets (6%) are supplanted by planktivorous phalaropes (25%), and piscivorous murres (38... more region, auklets (6%) are supplanted by planktivorous phalaropes (25%), and piscivorous murres (38%) and kittiwakes (15%). Average carbon flux to seabirds (0.65 mgC m -2 d -1 ) over the whole region is more typical of upwelling than shelf ecosystems. The pelagic distribution of seabirds in the region appears to be a function of advection, productivity and water column stability. Planktivores flourish in areas with high zooplankton concentrations on the edge of productive upwelling and frontal zones along the “Green Belt”, whereas piscivores avoid turbulent, mixed waters and forage in stable, stratified waters along the coast and in the central Chukchi Sea.
We have been conducting detailed studies of the biology of seabirds in relation to oceanography a... more We have been conducting detailed studies of the biology of seabirds in relation to oceanography and forage fish ecology in lower Cook Inlet, Alaska, since 1995. This fortuitously allowed us to document biological effects of the 1997/98 ENSO in this region. Anomalously warm sea surface temperatures (SST’s) were observed in the Gulf of Alaska (GOA) beginning in June of 1997, but not in Cook Inlet until September, 1997. Warm temperature anomalies at the surface and at depth persisted until May of 1998, when temperatures returned to average in the GOA and Cook Inlet. Thus, temperature anomalies occurred outside the core window of productivity (June-August) for forage fish and seabirds in both 1997 and 1998. Abundance or production of phytoplankton, zooplankton, fish, and seabirds in lower Cook Inlet varied among years, and overall appeared to be depressed in 1998. We observed a few biological anomalies that might be attributed to ENSO effects: 1) a significant die-off of Common Murres o...
Glacier Bay has long been known to harbor significant populations of Kittlitz’s Murrelet Brachyra... more Glacier Bay has long been known to harbor significant populations of Kittlitz’s Murrelet Brachyramphus brevirostris . Grinnell (1910) noted: “One of the more surprising results of the 1907 Alexander Expedition’s explorations was the discovery of large numbers of the Kittlitz’s Murrelet on the waters of Glacier Bay .” During July, Dixon (in Grinnell 1910) “saw at least five hundred of these gray murrelets in one flock . They were feeding in the channels among the numerous islands that lie near the mouth of the bay”—referring probably to Beardslee Channel, where large concentrations of Kittlitz’s Murrelets are still found . Early surveys in the upper reaches of the bay and in proximity to tidewater glaciers were infrequent because of heavy ice, but those that were conducted revealed that Kittlitz’s Murrelet and the closely related Marbled Murrelet B. marmoratus were distributed throughout the bay and that Kittlitz’s Murrelets, in particular, were concentrated in the vicinity of tidewa...
Some seabird populations damaged by the Exxon Valdez oil spill have not recovered, and population... more Some seabird populations damaged by the Exxon Valdez oil spill have not recovered, and populations will need to be monitored for many years to assess both recovery and ecological conditions affecting recovery. Detailed studies of individual seabird colonies and marine ecosystems in the Gulf of Alaska (GOA) have been conducted by the USGS and USFWS under the auspices of damage assessment and restoration programs of the EVOSTC. Much has been learned about factors influencing seabird populations and their capacity to recover from the spill in the GOA. As we move towards long-term monitoring of populations, however, we need to develop protocols and long-term monitoring strategies that focus on key parameters of interest and that are inexpensive, practical and applicable over a large geographic area.
Of the 24 species in the Auk (or Alcidae) family of seabirds living in the northern hemisphere, 2... more Of the 24 species in the Auk (or Alcidae) family of seabirds living in the northern hemisphere, 22 reside within the North Pacific Ocean. These “penguins of the north” use their small wings to “fly” underwater, some to more than 200 meters, where they catch and eat a variety of small fish and invertebrates. In terms of sheer numbers (>65 million) and food consumption, the Auks dominate seabird communities on our continental shelves and they serve as indicators of the health of our ocean. If Auk populations are not all thriving, then we should be concerned about the status of the oceans, plankton and fish that normally sustain them. A few Auk “tribes” genera) are abundant and widespread (such as Uria murres and Aethia auklets), and some are rare and isolated such as Synthliboramphus murrelets, including the Japanese “Crested” Murrelet). Only 8 species of Auk breed in Japan, including species that have either widespread or isolated populations in the North Pacific. During the past ...
Nearly half of the freshwater discharge into the Gulf of Alaska originates from landscapes draini... more Nearly half of the freshwater discharge into the Gulf of Alaska originates from landscapes draining glacier runoff, but the influence of the influx of riverine organic matter on the trophodynamics of coastal marine food webs is not well understood. We quantified the ecological impact of riverine organic matter subsidies to glacier-marine habitats by developing a multi-trophic level Bayesian three-isotope mixing model. We utilized large gradients in stable (δ(13) C, δ(15) N, δ(2) H) and radiogenic (Δ(14) C) isotopes that trace riverine and marine organic matter sources as they are passed from lower to higher trophic levels in glacial-marine habitats. We also compared isotope ratios between glacial-marine and more oceanic habitats. Based on isotopic measurements of potential baseline sources, ambient water and tissues of marine consumers, estimates of the riverine organic matter source contribution to upper trophic-level species including fish and seabirds ranged from 12-44%. Variabil...
Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer sea... more Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1-47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50-150 m) and reduced numbers over the shelf slope (200-500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod Calanus marshallae/glacialis were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock Gadus chalcogrammus near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the so...
ABSTRACT During the past decade, our research has focused on understanding predator and prey dist... more ABSTRACT During the past decade, our research has focused on understanding predator and prey distribution relative to marine habitat features in nearshore ecosystems, particularly glacial fjords in the Gulf of Alaska. These estuarine fjord systems are rapidly changing as a result of climate change, and they are host to a variety of piscivorous predators, including species of management concern such as the Kittlitz’s murrelet. We employed an ecosystem approach to sampling nearshore waters by measuring predator densities with respect to several important underlying factors that influence their dispersion, including a variety of oceanographic parameters and the abundance of phytoplankton, zooplankton and forage fish. Here we present an overview of our findings on the distribution and habitat relationships of important forage species including euphausiids, lanternfish, capelin, Pacific herring, Pacific sand lance, eulachon, and walleye pollock. In glacial-marine systems, freshwater inflow from glaciers is a structuring feature that strongly influences local temperatures, stratification and sedimentation. Phytoplankton are limited by light availability in surface waters near turbid glacier outflows, but zooplankton and forage fish are often abundant. Forage fish species differ in their response to habitat features. Some species, such as juvenile walleye pollock, exhibit high tolerance to oceanic conditions and are widely distributed whereas others, such as capelin and lanternfish, show greater preference for glacially modified waters and are therefore more limited in their distribution within fjords. Future work will investigate the role of glacier-derived nutrients to nearshore marine food webs in the Gulf of Alaska.
Marine ecosystems respond to a range of habitat variability in coastal zones modified by glacial ... more Marine ecosystems respond to a range of habitat variability in coastal zones modified by glacial freshwater outflows, biophysical data were collected in three study regions that included four major glacial fjord systems around the Gulf of Alaska. A suite of geographic, oceanographic, nutrient and biological attributes were sampled at these three study regions during peak ice-melt season in summer.
region, auklets (6%) are supplanted by planktivorous phalaropes (25%), and piscivorous murres (38... more region, auklets (6%) are supplanted by planktivorous phalaropes (25%), and piscivorous murres (38%) and kittiwakes (15%). Average carbon flux to seabirds (0.65 mgC m -2 d -1 ) over the whole region is more typical of upwelling than shelf ecosystems. The pelagic distribution of seabirds in the region appears to be a function of advection, productivity and water column stability. Planktivores flourish in areas with high zooplankton concentrations on the edge of productive upwelling and frontal zones along the “Green Belt”, whereas piscivores avoid turbulent, mixed waters and forage in stable, stratified waters along the coast and in the central Chukchi Sea.
We have been conducting detailed studies of the biology of seabirds in relation to oceanography a... more We have been conducting detailed studies of the biology of seabirds in relation to oceanography and forage fish ecology in lower Cook Inlet, Alaska, since 1995. This fortuitously allowed us to document biological effects of the 1997/98 ENSO in this region. Anomalously warm sea surface temperatures (SST’s) were observed in the Gulf of Alaska (GOA) beginning in June of 1997, but not in Cook Inlet until September, 1997. Warm temperature anomalies at the surface and at depth persisted until May of 1998, when temperatures returned to average in the GOA and Cook Inlet. Thus, temperature anomalies occurred outside the core window of productivity (June-August) for forage fish and seabirds in both 1997 and 1998. Abundance or production of phytoplankton, zooplankton, fish, and seabirds in lower Cook Inlet varied among years, and overall appeared to be depressed in 1998. We observed a few biological anomalies that might be attributed to ENSO effects: 1) a significant die-off of Common Murres o...
Glacier Bay has long been known to harbor significant populations of Kittlitz’s Murrelet Brachyra... more Glacier Bay has long been known to harbor significant populations of Kittlitz’s Murrelet Brachyramphus brevirostris . Grinnell (1910) noted: “One of the more surprising results of the 1907 Alexander Expedition’s explorations was the discovery of large numbers of the Kittlitz’s Murrelet on the waters of Glacier Bay .” During July, Dixon (in Grinnell 1910) “saw at least five hundred of these gray murrelets in one flock . They were feeding in the channels among the numerous islands that lie near the mouth of the bay”—referring probably to Beardslee Channel, where large concentrations of Kittlitz’s Murrelets are still found . Early surveys in the upper reaches of the bay and in proximity to tidewater glaciers were infrequent because of heavy ice, but those that were conducted revealed that Kittlitz’s Murrelet and the closely related Marbled Murrelet B. marmoratus were distributed throughout the bay and that Kittlitz’s Murrelets, in particular, were concentrated in the vicinity of tidewa...
Some seabird populations damaged by the Exxon Valdez oil spill have not recovered, and population... more Some seabird populations damaged by the Exxon Valdez oil spill have not recovered, and populations will need to be monitored for many years to assess both recovery and ecological conditions affecting recovery. Detailed studies of individual seabird colonies and marine ecosystems in the Gulf of Alaska (GOA) have been conducted by the USGS and USFWS under the auspices of damage assessment and restoration programs of the EVOSTC. Much has been learned about factors influencing seabird populations and their capacity to recover from the spill in the GOA. As we move towards long-term monitoring of populations, however, we need to develop protocols and long-term monitoring strategies that focus on key parameters of interest and that are inexpensive, practical and applicable over a large geographic area.
Of the 24 species in the Auk (or Alcidae) family of seabirds living in the northern hemisphere, 2... more Of the 24 species in the Auk (or Alcidae) family of seabirds living in the northern hemisphere, 22 reside within the North Pacific Ocean. These “penguins of the north” use their small wings to “fly” underwater, some to more than 200 meters, where they catch and eat a variety of small fish and invertebrates. In terms of sheer numbers (>65 million) and food consumption, the Auks dominate seabird communities on our continental shelves and they serve as indicators of the health of our ocean. If Auk populations are not all thriving, then we should be concerned about the status of the oceans, plankton and fish that normally sustain them. A few Auk “tribes” genera) are abundant and widespread (such as Uria murres and Aethia auklets), and some are rare and isolated such as Synthliboramphus murrelets, including the Japanese “Crested” Murrelet). Only 8 species of Auk breed in Japan, including species that have either widespread or isolated populations in the North Pacific. During the past ...
Nearly half of the freshwater discharge into the Gulf of Alaska originates from landscapes draini... more Nearly half of the freshwater discharge into the Gulf of Alaska originates from landscapes draining glacier runoff, but the influence of the influx of riverine organic matter on the trophodynamics of coastal marine food webs is not well understood. We quantified the ecological impact of riverine organic matter subsidies to glacier-marine habitats by developing a multi-trophic level Bayesian three-isotope mixing model. We utilized large gradients in stable (δ(13) C, δ(15) N, δ(2) H) and radiogenic (Δ(14) C) isotopes that trace riverine and marine organic matter sources as they are passed from lower to higher trophic levels in glacial-marine habitats. We also compared isotope ratios between glacial-marine and more oceanic habitats. Based on isotopic measurements of potential baseline sources, ambient water and tissues of marine consumers, estimates of the riverine organic matter source contribution to upper trophic-level species including fish and seabirds ranged from 12-44%. Variabil...
Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer sea... more Timing of spring sea-ice retreat shapes the southeast Bering Sea food web. We compared summer seabird densities and average bathymetry depth distributions between years with early (typically warm) and late (typically cold) ice retreat. Averaged over all seabird species, densities in early-ice-retreat-years were 10.1% (95% CI: 1.1-47.9%) of that in late-ice-retreat-years. In early-ice-retreat-years, surface-foraging species had increased numbers over the middle shelf (50-150 m) and reduced numbers over the shelf slope (200-500 m). Pursuit-diving seabirds showed a less clear trend. Euphausiids and the copepod Calanus marshallae/glacialis were 2.4 and 18.1 times less abundant in early-ice-retreat-years, respectively, whereas age-0 walleye pollock Gadus chalcogrammus near-surface densities were 51× higher in early-ice-retreat-years. Our results suggest a mechanistic understanding of how present and future changes in sea-ice-retreat timing may affect top predators like seabirds in the so...
ABSTRACT During the past decade, our research has focused on understanding predator and prey dist... more ABSTRACT During the past decade, our research has focused on understanding predator and prey distribution relative to marine habitat features in nearshore ecosystems, particularly glacial fjords in the Gulf of Alaska. These estuarine fjord systems are rapidly changing as a result of climate change, and they are host to a variety of piscivorous predators, including species of management concern such as the Kittlitz’s murrelet. We employed an ecosystem approach to sampling nearshore waters by measuring predator densities with respect to several important underlying factors that influence their dispersion, including a variety of oceanographic parameters and the abundance of phytoplankton, zooplankton and forage fish. Here we present an overview of our findings on the distribution and habitat relationships of important forage species including euphausiids, lanternfish, capelin, Pacific herring, Pacific sand lance, eulachon, and walleye pollock. In glacial-marine systems, freshwater inflow from glaciers is a structuring feature that strongly influences local temperatures, stratification and sedimentation. Phytoplankton are limited by light availability in surface waters near turbid glacier outflows, but zooplankton and forage fish are often abundant. Forage fish species differ in their response to habitat features. Some species, such as juvenile walleye pollock, exhibit high tolerance to oceanic conditions and are widely distributed whereas others, such as capelin and lanternfish, show greater preference for glacially modified waters and are therefore more limited in their distribution within fjords. Future work will investigate the role of glacier-derived nutrients to nearshore marine food webs in the Gulf of Alaska.
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