Laminaria pallida and Ecklonia maxima are large, commercially valuable kelps that co-dominate ins... more Laminaria pallida and Ecklonia maxima are large, commercially valuable kelps that co-dominate inshore waters of the west coast of Southern Africa in a geographically changing pattern. In the south, E. maxima dominates and forms a canopy in shallow waters (< about 5 m deep), with L. pallida forming a sub-canopy and extending down to 20 m or more. Northward along the Southern African coast and into Namibia, E. maxima is progressively replaced by L. pallida. Corresponding with this change in dominance, L. pallida shows certain morphological changes along the south-to-north geographical gradient. To explain these phenomena, we examined a range of morphological characters in both kelps (stipe length, stipe weight, stipe outer diameter, stipe inner diameter, length of hollow section in the stipe, and frond weight), and various environmental factors (seawater temperature, seawater turbidity, cloud/fog data, daylength, and wave and wind data). Our results, based on measurements at seven sites along 1600 km of coast between Cape Town and Swakopmund (Namibia), quantified and confirmed the change in dominance and the northward increase in stipe hollowness in L. pallida. The morphology of E. maxima did not change with latitude. Water turbidity, wind speed, and wave height differed significantly along the coast. However, only turbidity showed a steady trend, increasing northward in terms of all indicators (chlorophyll a, particulate inorganic carbon, particulate organic carbon) while wind speed and wave height showed a generally decreasing trend. Furthermore, the hollowness of L. pallida was also not related to the flexibility of the stipes. Our results suggest that L. pallida sporophytes may progressively outcompete E. maxima northward, perhaps because they are more low-light tolerant, and we suggest that by developing a hollow stipe, the sporophytes may grow faster in length, potentially increasing their competitive advantage in the shallow water where they must compete with sporophytes of E. maxima.
When exposed to Prudhoe Bay crude oil in flowing
seawater for 180 days, the small intertidal cla... more When exposed to Prudhoe Bay crude oil in flowing
seawater for 180 days, the small intertidal clam Macoma
balthica showed behavioral, physical, physiological and
biochemical changes. At a high concentration of oil in
seawater (3.0 mg l-1 ) burrowing rate decreased , respiration rate increased, growth was inhibited , and very high
mortalities resulted. The lowest concentration of oil in
seawater (0.03 mg l_ l ) inhibited growth and caused
reabsorption of gametes. One group of adverse oil effects
which was related to sluggishness and disorientation of
the clams appeared after a week of exposure to oil;
another group related to a negative energy balance was
not observed until 60 days. We conclude that chronic
exposure ofM. balthica to oil-in-seawater concentrations
even as low as 0.03 mg T1 will, in time, lead to population decreases.
Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the... more Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the heavily oiled portions of western Prince William Sound following the Exxon Valdez oil spill of March 1989. The initial effects were most pronounced in more protected eelgrass and silled fjord habitats, where PAH (polycyclic aromatic hydrocarbon) concentrations in sediments exceeded 1000 ng g-1 in 1990. By 1993, PAH concentrations in sediments declined to less than 100 ng g-1, and there were far fewer differences between oiled and control sites with respect to the abundance of dominant plant, invertebrate, and fish taxa. However, not all taxa had recovered fully.
We studied genetic variation of fitness traits in a population of salmon that is not captive but ... more We studied genetic variation of fitness traits in a population of salmon that is not captive but spawns naturally and grows to maturity in nature. Additive genetic variation contributed significantly to variation of fecundity, a trait closely related to fitness, but not to variation of egg size (another trait closely related to fitness) in families drawn from an anadromous population of salmon and measured after growing to maturity in the wild. Greater fecundity-at-length in families drawn from the early-spawning component of the population suggests that variation of fecundity is itself adaptive. The families were generated by hierarchical mating of 60 male pink salmon to 120 females randomly chosen from the odd-year population at Auke Creek, Juneau, Alaska, 2 females to each male. Half were from the early (August-spawning) component and half from the late (September-spawning) component. The families were incubated separately, tagged with coded microwires, released during emigration...
Alaska has the longest coastline of all of the states in the USA. This coastal zone stretches fro... more Alaska has the longest coastline of all of the states in the USA. This coastal zone stretches from the temperate zone to past the Arctic circle. Oceanographic conditions vary from quiet estuaries to exposed open coasts. Water temperatures range from over 20°C in the summer in the south to ice covered water in the north. Consequently, the marine flora is plentiful and diverse with over 500 species of seaweeds. Three species of floating kelps occur from the southern boundary to Kodiak Island and westward along the Aleutian Chain. Species of Fucus are dominant in the intertidal along most of the coastline. There is also an abundance of red algae in the intertidal and subtidal. There is only minimal subsistence and commercial utilization of the seaweed resource. The major commercial use of seaweeds is in the herring spawn-on-kelp fishery. “Black seaweed” (Pyropia sp.) is a special resource for Alaskan Native subsistence harvest. Recently, there has been increasing interest and activity ...
... aged gold mill effluent was compared for two reference species (juvenile mysid shrimp [Mysido... more ... aged gold mill effluent was compared for two reference species (juvenile mysid shrimp [Mysidopsisbahia (Americamysis bahia)] and larval sheepshead minnows [Cyprinodon variegatus]) and larvae of three species that are indigenous to the southern coast of Alaska (red king ...
Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the... more Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the heavily oiled portions of western Prince William Sound following the Exxon Valdez oil spill of March 1989. The initial effects were most pronounced in more protected eelgrass and silled fjord habitats, where PAH (polycyclic aromatic hydrocarbon) concentrations in sediments exceeded 1000 ng g-1 in 1990. By 1993, PAH concentrations in sediments declined to less than 100 ng g-1, and there were far fewer differences between oiled and control sites with respect to the abundance of dominant plant, invertebrate, and fish taxa. However, not all taxa had recovered fully.
Comparative Biochemistry and Physiology Part C Comparative Pharmacology and Toxicology, Feb 1, 1984
Coho salmon exposed to the water soluble fraction (WSF) of Cook Inlet crude oil for a maximum of ... more Coho salmon exposed to the water soluble fraction (WSF) of Cook Inlet crude oil for a maximum of 30 days showed a greater than three-fold increase in hepatic aryl hydrocarbon hydroxylase activity. The initial increase in enzyme activity appeared between 2 and 5 days of exposure and increased as a function of increased exposure time. Persistence of the induced enzyme activity was dependent on the length and the concentration of WSF exposure. Handling stress had no effect on the AHH activity, but starvation caused a decrease in the activity.
Laminaria pallida and Ecklonia maxima are large, commercially valuable kelps that co-dominate ins... more Laminaria pallida and Ecklonia maxima are large, commercially valuable kelps that co-dominate inshore waters of the west coast of Southern Africa in a geographically changing pattern. In the south, E. maxima dominates and forms a canopy in shallow waters (< about 5 m deep), with L. pallida forming a sub-canopy and extending down to 20 m or more. Northward along the Southern African coast and into Namibia, E. maxima is progressively replaced by L. pallida. Corresponding with this change in dominance, L. pallida shows certain morphological changes along the south-to-north geographical gradient. To explain these phenomena, we examined a range of morphological characters in both kelps (stipe length, stipe weight, stipe outer diameter, stipe inner diameter, length of hollow section in the stipe, and frond weight), and various environmental factors (seawater temperature, seawater turbidity, cloud/fog data, daylength, and wave and wind data). Our results, based on measurements at seven sites along 1600 km of coast between Cape Town and Swakopmund (Namibia), quantified and confirmed the change in dominance and the northward increase in stipe hollowness in L. pallida. The morphology of E. maxima did not change with latitude. Water turbidity, wind speed, and wave height differed significantly along the coast. However, only turbidity showed a steady trend, increasing northward in terms of all indicators (chlorophyll a, particulate inorganic carbon, particulate organic carbon) while wind speed and wave height showed a generally decreasing trend. Furthermore, the hollowness of L. pallida was also not related to the flexibility of the stipes. Our results suggest that L. pallida sporophytes may progressively outcompete E. maxima northward, perhaps because they are more low-light tolerant, and we suggest that by developing a hollow stipe, the sporophytes may grow faster in length, potentially increasing their competitive advantage in the shallow water where they must compete with sporophytes of E. maxima.
When exposed to Prudhoe Bay crude oil in flowing
seawater for 180 days, the small intertidal cla... more When exposed to Prudhoe Bay crude oil in flowing
seawater for 180 days, the small intertidal clam Macoma
balthica showed behavioral, physical, physiological and
biochemical changes. At a high concentration of oil in
seawater (3.0 mg l-1 ) burrowing rate decreased , respiration rate increased, growth was inhibited , and very high
mortalities resulted. The lowest concentration of oil in
seawater (0.03 mg l_ l ) inhibited growth and caused
reabsorption of gametes. One group of adverse oil effects
which was related to sluggishness and disorientation of
the clams appeared after a week of exposure to oil;
another group related to a negative energy balance was
not observed until 60 days. We conclude that chronic
exposure ofM. balthica to oil-in-seawater concentrations
even as low as 0.03 mg T1 will, in time, lead to population decreases.
Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the... more Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the heavily oiled portions of western Prince William Sound following the Exxon Valdez oil spill of March 1989. The initial effects were most pronounced in more protected eelgrass and silled fjord habitats, where PAH (polycyclic aromatic hydrocarbon) concentrations in sediments exceeded 1000 ng g-1 in 1990. By 1993, PAH concentrations in sediments declined to less than 100 ng g-1, and there were far fewer differences between oiled and control sites with respect to the abundance of dominant plant, invertebrate, and fish taxa. However, not all taxa had recovered fully.
We studied genetic variation of fitness traits in a population of salmon that is not captive but ... more We studied genetic variation of fitness traits in a population of salmon that is not captive but spawns naturally and grows to maturity in nature. Additive genetic variation contributed significantly to variation of fecundity, a trait closely related to fitness, but not to variation of egg size (another trait closely related to fitness) in families drawn from an anadromous population of salmon and measured after growing to maturity in the wild. Greater fecundity-at-length in families drawn from the early-spawning component of the population suggests that variation of fecundity is itself adaptive. The families were generated by hierarchical mating of 60 male pink salmon to 120 females randomly chosen from the odd-year population at Auke Creek, Juneau, Alaska, 2 females to each male. Half were from the early (August-spawning) component and half from the late (September-spawning) component. The families were incubated separately, tagged with coded microwires, released during emigration...
Alaska has the longest coastline of all of the states in the USA. This coastal zone stretches fro... more Alaska has the longest coastline of all of the states in the USA. This coastal zone stretches from the temperate zone to past the Arctic circle. Oceanographic conditions vary from quiet estuaries to exposed open coasts. Water temperatures range from over 20°C in the summer in the south to ice covered water in the north. Consequently, the marine flora is plentiful and diverse with over 500 species of seaweeds. Three species of floating kelps occur from the southern boundary to Kodiak Island and westward along the Aleutian Chain. Species of Fucus are dominant in the intertidal along most of the coastline. There is also an abundance of red algae in the intertidal and subtidal. There is only minimal subsistence and commercial utilization of the seaweed resource. The major commercial use of seaweeds is in the herring spawn-on-kelp fishery. “Black seaweed” (Pyropia sp.) is a special resource for Alaskan Native subsistence harvest. Recently, there has been increasing interest and activity ...
... aged gold mill effluent was compared for two reference species (juvenile mysid shrimp [Mysido... more ... aged gold mill effluent was compared for two reference species (juvenile mysid shrimp [Mysidopsisbahia (Americamysis bahia)] and larval sheepshead minnows [Cyprinodon variegatus]) and larvae of three species that are indigenous to the southern coast of Alaska (red king ...
Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the... more Injuries to several of the dominant taxa in the nearshore subtidal community were observed in the heavily oiled portions of western Prince William Sound following the Exxon Valdez oil spill of March 1989. The initial effects were most pronounced in more protected eelgrass and silled fjord habitats, where PAH (polycyclic aromatic hydrocarbon) concentrations in sediments exceeded 1000 ng g-1 in 1990. By 1993, PAH concentrations in sediments declined to less than 100 ng g-1, and there were far fewer differences between oiled and control sites with respect to the abundance of dominant plant, invertebrate, and fish taxa. However, not all taxa had recovered fully.
Comparative Biochemistry and Physiology Part C Comparative Pharmacology and Toxicology, Feb 1, 1984
Coho salmon exposed to the water soluble fraction (WSF) of Cook Inlet crude oil for a maximum of ... more Coho salmon exposed to the water soluble fraction (WSF) of Cook Inlet crude oil for a maximum of 30 days showed a greater than three-fold increase in hepatic aryl hydrocarbon hydroxylase activity. The initial increase in enzyme activity appeared between 2 and 5 days of exposure and increased as a function of increased exposure time. Persistence of the induced enzyme activity was dependent on the length and the concentration of WSF exposure. Handling stress had no effect on the AHH activity, but starvation caused a decrease in the activity.
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seawater for 180 days, the small intertidal clam Macoma
balthica showed behavioral, physical, physiological and
biochemical changes. At a high concentration of oil in
seawater (3.0 mg l-1 ) burrowing rate decreased , respiration rate increased, growth was inhibited , and very high
mortalities resulted. The lowest concentration of oil in
seawater (0.03 mg l_ l ) inhibited growth and caused
reabsorption of gametes. One group of adverse oil effects
which was related to sluggishness and disorientation of
the clams appeared after a week of exposure to oil;
another group related to a negative energy balance was
not observed until 60 days. We conclude that chronic
exposure ofM. balthica to oil-in-seawater concentrations
even as low as 0.03 mg T1 will, in time, lead to population decreases.
seawater for 180 days, the small intertidal clam Macoma
balthica showed behavioral, physical, physiological and
biochemical changes. At a high concentration of oil in
seawater (3.0 mg l-1 ) burrowing rate decreased , respiration rate increased, growth was inhibited , and very high
mortalities resulted. The lowest concentration of oil in
seawater (0.03 mg l_ l ) inhibited growth and caused
reabsorption of gametes. One group of adverse oil effects
which was related to sluggishness and disorientation of
the clams appeared after a week of exposure to oil;
another group related to a negative energy balance was
not observed until 60 days. We conclude that chronic
exposure ofM. balthica to oil-in-seawater concentrations
even as low as 0.03 mg T1 will, in time, lead to population decreases.