Canadian Journal of Fisheries and Aquatic Sciences, Nov 1, 1991
Responses of stream periphytic algae and benthic insects to increases in dissolved inorganic phos... more Responses of stream periphytic algae and benthic insects to increases in dissolved inorganic phosphorus (P) were assessed in a streamside mesocosm. Controls and treatments were colonized continuously in summer by biota from the stream. P was maintained in the treatments at 10 μg∙L−1, [Formula: see text] times the concentration in the controls. In the treatments the biomass of chlorophyll a reached 3.5 times that of the controls, accompanied by an increase in Cyanophyta relative to diatoms. No difference was detectable in the numbers of insects drifting from controls and treatments. Numbers of individuals emerging (> 40 species) from the treatments over 7 wk were 2.2 times those from the controls. In both controls and treatments, 77% or more of emerging insects were Chironomidae. After week 7 the density of benthic insects in the treatments, determined without size selection, was 1.75 times that of the controls; size distributions in treatments and controls were similar. Addition of P, therefore, increased the food of insects and resulted in a doubling of their survival to emergence.
Part way through a year-long water quality field survey, the Capilano Reservoir, located in the G... more Part way through a year-long water quality field survey, the Capilano Reservoir, located in the Greater Vancouver Water District, was drawn down to accommodate earthquake reinforcement work on the Cleveland Dam. This paper reports observations of the effect of drawdown on water quality in the reservoir, in the context of the original study. The drawdown exposed a large zone of deltaic material through which the Capilano River eroded a path up to 2.5 m deep. The deltaic material contained substantial amounts of nitrogen and iron (TKN, 4,470 mg kg-1; total iron, 21,800 mg kg-1). During drawdown, turbidity in the reservoir increased up to 25 times as compared to prior conditions. Ammonium (NH4+-N) and dissolved and particulate iron concentrations in the drawdown zone were up to two orders of magnitude higher than concentrations upstream. Both NH4+-N and dissolved iron were observed to travel the length of the reservoir. Persistence of NH4+-N in the highly oxygenated conditions may be e...
To avoid the formation of organochlorine compounds in pulp products and effluents discharged into... more To avoid the formation of organochlorine compounds in pulp products and effluents discharged into the environment, there is a trend in the North American pulping industry to change from molecular chlorine to chlorine dioxide bleaching. However, chlorate (ClO3−) formed during chlorine dioxide bleaching is known to have toxic effects in some marine algae and has been implicated in environmental problems in the Baltic Sea. This study examined the potential effects of chlorate on natural freshwater, riverine diatom communities characteristic of many rivers in western Canada. Under low ambient river nitrate concentrations (ca. 10 µg•L−1 NO3−N), chlorate additions of up to 500 µg•L1 ClO3 did not reduce the specific growth rates (µ) or change the taxonomic composition of the attached riverine diatom community. The lack of chlorate toxicity to freshwater diatoms suggests that the nitrate uptake and/or reduction mechanism(s) of freshwater diatoms have much higher affinities for NO3 than ClO3...
Canadian Journal of Fisheries and Aquatic Sciences, 2019
The increasing rate of glacier retreat and turbid glacial runoff can have a strong influence on f... more The increasing rate of glacier retreat and turbid glacial runoff can have a strong influence on freshwater ecosystems. Seton and Anderson lakes (British Columbia, Canada) are sockeye salmon (Oncorhynchus nerka) nursery systems. Since the 1940s, the Bridge River Diversion (BRD) introduced glacially turbid water into Seton Lake. To assess the impact of the BRD on the production of Seton Lake, we combined data from limnological surveys with the analysis of subfossil cladocerans and diatoms from sediment cores, using Anderson Lake as a reference. The modern data indicate that the euphotic zone is 14 m shallower and the cladoceran density and biomass are significantly lower in Seton Lake in comparison with Anderson Lake. The paleo-data indicate that following the BRD, the sedimentary fluxes of cladoceran and diatom declined 2- to 10-fold in Seton Lake and remained low thereafter. Together, our data support declines in primary and secondary producers following the BRD, likely due to chang...
The Coho Salmon, Oncorhynchus kisutch, is one of seven species of Pacific salmon and trout native... more The Coho Salmon, Oncorhynchus kisutch, is one of seven species of Pacific salmon and trout native to northeastern Pacific Ocean watersheds. The species is typically anadromous; adults reproduce in fresh water where juveniles reside for 1–2 years before seaward migration after which the majority of growth occurs in the ocean before maturation at 2–4 years old when adults return to fresh water to spawn. Here, we report maturation of Coho Salmon in two freshwater lakes on the north coast of British Columbia apparently without their being to sea. A total of 15 mature fish (11 males and four females) were collected in two lakes across two years. The mature fish were all at least 29 cm in total length and ranged in age from three to five years old. The occurrence of Coho Salmon that have matured in fresh water without first going to sea is exceedingly rare in their natural range, especially for females. Such mature Coho Salmon may represent residual and distinct breeding populations from ...
North American Journal of Fisheries Management, 2006
An innovative coupling of nutrient addition and biomanipulation strategies was applied to Wahleac... more An innovative coupling of nutrient addition and biomanipulation strategies was applied to Wahleach Reservoir in southwestern British Columbia to successfully restore fish populations. Kokanee Oncorhynchus nerka were historically abundant in the reservoir, but the population collapsed over 2 decades. This decline in kokanee abundance and a concurrent decline in the catch rates of rainbow trout Oncorhynchus mykiss coincided with the occurrence of trophic depression in the aging reservoir. It also coincided with the onset of food competition with threespine sticklebacks Gasterosteus aculeatus that were illegally introduced in the 1970s. In 1995 through 2000, the reservoir was fertilized with liquid fertilizer with compositions of 10–34–0 and 28–0−0 at an annual P load of up to 225 mg/m2 of lake water (late May through September) at a molar N:P ratio of 25 in 1995, declining to 13 in 2000. Up to 50,000 age‐0 kokanee (up to 4.5 g) and approximately 20,000 triploid cutthroat trout O. clar...
North American Journal of Fisheries Management, 2005
Coordinated acoustic and trawl surveys were performed to locate aggregations of adult eulachon Th... more Coordinated acoustic and trawl surveys were performed to locate aggregations of adult eulachon Thaleichthys pacificus in the lower Fraser River, British Columbia, during spring 2001 and 2002. Aggregations were encountered in one portion of the study area in both years. They contained mature, spawning, and spent eulachon of both sexes, of which over 80% were spent males. These groups were 880–2,000 m long and averaged 117–140 m wide. Within them, mean fish density was 0.27–0.29 fish/m3 and species composition was 87–99% eulachon. They occurred in 6–8.5 m of water over substrate that was mainly sand with a small fraction of pea gravel. We did not determine whether these eulachon spawned in that area or had congregated there for another purpose, such as holding or migration. Other species occasionally encountered in appreciable numbers were juvenile pink salmon Oncorhynchus gorbuscha and chum salmon O. keta. Mean in situ target strengths of eulachon were −53.3 dB at 123 kHz and −50.3 d...
Canadian Journal of Fisheries and Aquatic Sciences, 1984
Forest fertilization (435 kg urea∙ha−1) on the Mohun drainage, northern Vancouver Island, during ... more Forest fertilization (435 kg urea∙ha−1) on the Mohun drainage, northern Vancouver Island, during late fall 1979 resulted in a combined increase in urea, ammonia, and nitrate concentrations to 8000 μg N∙L−1 above control levels in streams not protected with 50-m-wide leave (i.e. unfertilized) strips and 350 μg N∙L−1 in those having leave strips. By spring 1980, dissolved nitrogen loads to Mohun Lake increased by a minimum of 55% in the largest basin and 1924% in the smallest basin. This corresponded to fertilizer losses of 2.1% of the total applied from drainages that had leave strips and up to 5.2% from those where the treatment included direct application to stream channels. Nitrogen transport was dominated by reduced nitrogen species and lasted up to 144 d. Relatively small changes in nitrate transport were attributed to low temperatures, which reduced rates of nitrification. Duringthe3-yr prior to forest fertilization, nitrogen and phosphorus were added to the lake at an N:P rati...
Canadian Journal of Fisheries and Aquatic Sciences, 1990
Nutrient concentrations, periphyton standing crop and size of steelhead trout (Oncorhynchus mykis... more Nutrient concentrations, periphyton standing crop and size of steelhead trout (Oncorhynchus mykiss) and coho salmon (O, kisutch) fry increased after the fertilization of a nutrient-deficient stream with inorganic phosphorus (P) and nitrogen (N). Whole-river fertilization of the Keogh River, British Columbia, during 1983–86 to increase summer average nutrient concentrations from < 1 μg P∙L−1 and 25 μg N∙L−1 to 10–15 μg P∙L−1 and 30–100 μg N∙L−1 resulted in five- to 10-fold increases in periphyton standing crops on artificial substrata and 1.4- to 2.0-fold increases in late-September salmonid fry weights. Diatoms and chlorophytes dominated the algal periphyton on artificial substrata at fertilized sites. Cyanophytes were unimportant despite low N:P ratios in some cases. Juvenile salmonids fed primarily on benthic insects. These results suggest that autochthonous primary production can be an important energy source in forested, middle-order streams, and indicate that the manipulatio...
Canadian Journal of Fisheries and Aquatic Sciences, 1987
Periphyton accumulation rates and alkaline phosphatase activity were examined in reaches of the K... more Periphyton accumulation rates and alkaline phosphatase activity were examined in reaches of the Keogh River, British Columbia, following additions of grain and inorganic fertilizer as separate treatments during spring–summer 1981. Two different levels of N and P addition were used: one to attain ambient N and P concentrations of 200 and 15 μg∙L−1, respectively, and the other to attain 400 and 20 μg∙L−1, respectively. Grain (rolled barley) was added monthly at 280 g∙m−2. N and P additions increased chlorophyll a accrual rates by more than an order of magnitude. Diatoms dominated the periphyton community until midsummer. In July and most of August, the relative importance of chlorophytes increased and biomass levels declined markedly in spite of continued nutrient additions. Grain additions resulted in no detectable change in periphyton accrual, but alkaline phosphatase activity increased by 35% over control levels. These results suggest that additions of labile organic matter to nutr...
Canadian Journal of Fisheries and Aquatic Sciences, 1994
Commercial formulations of the insecticidal bacterium Bacillus thuringiensis var. kurstaki (Btk) ... more Commercial formulations of the insecticidal bacterium Bacillus thuringiensis var. kurstaki (Btk) are frequently sprayed over bodies of water. The hypothesis that Btk poses a threat to stream communities was tested using streamside, flow-through mesocosms which received water and invertebrate colonists from a second-order stream in southwestern British Columbia; low (50 BIU/ha) and high (≥ 5000 BIU/ha) treatment levels were contrasted with controls. There were no significant differences in the density or composition of benthos sampled 7 d after Btk application. The densities were highest in the high-dose mesocosms. There were no significant differences in emergence rate of adults due to treatment. During the 2.5-h treatment, there were marginally elevated drift rates of the mayfly Baetis when exposed to the solution, but these differences were negated during the remainder of the 24-h period. Leaf packs lost significantly more mass in controls than in high-dose mesocosms, but there we...
Page 1. BULLETIN OF MARINE SCIENCE. 55(2-3): 1160-1180. 1994 DEBRIS STRUCTURE PLACEMENTS AND WHOL... more Page 1. BULLETIN OF MARINE SCIENCE. 55(2-3): 1160-1180. 1994 DEBRIS STRUCTURE PLACEMENTS AND WHOLE-RIVER FERTILIZATION FOR SALMONIDS IN A LARGE REGULATED STREAM IN BRITISH COLUMBIA ...
Transactions of the American Fisheries Society, 2003
... Transactions of the American Fisheries Society , 124: 857872. [Taylor &amp;amp; Francis ... more ... Transactions of the American Fisheries Society , 124: 857872. [Taylor &amp;amp; Francis Online], [Web of Science ®], [CSA] View all references). ... View all references; Desloges and Church 198910. Desloges, JR and Church, M. 1989. ...
Canadian Journal of Fisheries and Aquatic Sciences, Nov 1, 1991
Responses of stream periphytic algae and benthic insects to increases in dissolved inorganic phos... more Responses of stream periphytic algae and benthic insects to increases in dissolved inorganic phosphorus (P) were assessed in a streamside mesocosm. Controls and treatments were colonized continuously in summer by biota from the stream. P was maintained in the treatments at 10 μg∙L−1, [Formula: see text] times the concentration in the controls. In the treatments the biomass of chlorophyll a reached 3.5 times that of the controls, accompanied by an increase in Cyanophyta relative to diatoms. No difference was detectable in the numbers of insects drifting from controls and treatments. Numbers of individuals emerging (&gt; 40 species) from the treatments over 7 wk were 2.2 times those from the controls. In both controls and treatments, 77% or more of emerging insects were Chironomidae. After week 7 the density of benthic insects in the treatments, determined without size selection, was 1.75 times that of the controls; size distributions in treatments and controls were similar. Addition of P, therefore, increased the food of insects and resulted in a doubling of their survival to emergence.
Part way through a year-long water quality field survey, the Capilano Reservoir, located in the G... more Part way through a year-long water quality field survey, the Capilano Reservoir, located in the Greater Vancouver Water District, was drawn down to accommodate earthquake reinforcement work on the Cleveland Dam. This paper reports observations of the effect of drawdown on water quality in the reservoir, in the context of the original study. The drawdown exposed a large zone of deltaic material through which the Capilano River eroded a path up to 2.5 m deep. The deltaic material contained substantial amounts of nitrogen and iron (TKN, 4,470 mg kg-1; total iron, 21,800 mg kg-1). During drawdown, turbidity in the reservoir increased up to 25 times as compared to prior conditions. Ammonium (NH4+-N) and dissolved and particulate iron concentrations in the drawdown zone were up to two orders of magnitude higher than concentrations upstream. Both NH4+-N and dissolved iron were observed to travel the length of the reservoir. Persistence of NH4+-N in the highly oxygenated conditions may be e...
To avoid the formation of organochlorine compounds in pulp products and effluents discharged into... more To avoid the formation of organochlorine compounds in pulp products and effluents discharged into the environment, there is a trend in the North American pulping industry to change from molecular chlorine to chlorine dioxide bleaching. However, chlorate (ClO3−) formed during chlorine dioxide bleaching is known to have toxic effects in some marine algae and has been implicated in environmental problems in the Baltic Sea. This study examined the potential effects of chlorate on natural freshwater, riverine diatom communities characteristic of many rivers in western Canada. Under low ambient river nitrate concentrations (ca. 10 µg•L−1 NO3−N), chlorate additions of up to 500 µg•L1 ClO3 did not reduce the specific growth rates (µ) or change the taxonomic composition of the attached riverine diatom community. The lack of chlorate toxicity to freshwater diatoms suggests that the nitrate uptake and/or reduction mechanism(s) of freshwater diatoms have much higher affinities for NO3 than ClO3...
Canadian Journal of Fisheries and Aquatic Sciences, 2019
The increasing rate of glacier retreat and turbid glacial runoff can have a strong influence on f... more The increasing rate of glacier retreat and turbid glacial runoff can have a strong influence on freshwater ecosystems. Seton and Anderson lakes (British Columbia, Canada) are sockeye salmon (Oncorhynchus nerka) nursery systems. Since the 1940s, the Bridge River Diversion (BRD) introduced glacially turbid water into Seton Lake. To assess the impact of the BRD on the production of Seton Lake, we combined data from limnological surveys with the analysis of subfossil cladocerans and diatoms from sediment cores, using Anderson Lake as a reference. The modern data indicate that the euphotic zone is 14 m shallower and the cladoceran density and biomass are significantly lower in Seton Lake in comparison with Anderson Lake. The paleo-data indicate that following the BRD, the sedimentary fluxes of cladoceran and diatom declined 2- to 10-fold in Seton Lake and remained low thereafter. Together, our data support declines in primary and secondary producers following the BRD, likely due to chang...
The Coho Salmon, Oncorhynchus kisutch, is one of seven species of Pacific salmon and trout native... more The Coho Salmon, Oncorhynchus kisutch, is one of seven species of Pacific salmon and trout native to northeastern Pacific Ocean watersheds. The species is typically anadromous; adults reproduce in fresh water where juveniles reside for 1–2 years before seaward migration after which the majority of growth occurs in the ocean before maturation at 2–4 years old when adults return to fresh water to spawn. Here, we report maturation of Coho Salmon in two freshwater lakes on the north coast of British Columbia apparently without their being to sea. A total of 15 mature fish (11 males and four females) were collected in two lakes across two years. The mature fish were all at least 29 cm in total length and ranged in age from three to five years old. The occurrence of Coho Salmon that have matured in fresh water without first going to sea is exceedingly rare in their natural range, especially for females. Such mature Coho Salmon may represent residual and distinct breeding populations from ...
North American Journal of Fisheries Management, 2006
An innovative coupling of nutrient addition and biomanipulation strategies was applied to Wahleac... more An innovative coupling of nutrient addition and biomanipulation strategies was applied to Wahleach Reservoir in southwestern British Columbia to successfully restore fish populations. Kokanee Oncorhynchus nerka were historically abundant in the reservoir, but the population collapsed over 2 decades. This decline in kokanee abundance and a concurrent decline in the catch rates of rainbow trout Oncorhynchus mykiss coincided with the occurrence of trophic depression in the aging reservoir. It also coincided with the onset of food competition with threespine sticklebacks Gasterosteus aculeatus that were illegally introduced in the 1970s. In 1995 through 2000, the reservoir was fertilized with liquid fertilizer with compositions of 10–34–0 and 28–0−0 at an annual P load of up to 225 mg/m2 of lake water (late May through September) at a molar N:P ratio of 25 in 1995, declining to 13 in 2000. Up to 50,000 age‐0 kokanee (up to 4.5 g) and approximately 20,000 triploid cutthroat trout O. clar...
North American Journal of Fisheries Management, 2005
Coordinated acoustic and trawl surveys were performed to locate aggregations of adult eulachon Th... more Coordinated acoustic and trawl surveys were performed to locate aggregations of adult eulachon Thaleichthys pacificus in the lower Fraser River, British Columbia, during spring 2001 and 2002. Aggregations were encountered in one portion of the study area in both years. They contained mature, spawning, and spent eulachon of both sexes, of which over 80% were spent males. These groups were 880–2,000 m long and averaged 117–140 m wide. Within them, mean fish density was 0.27–0.29 fish/m3 and species composition was 87–99% eulachon. They occurred in 6–8.5 m of water over substrate that was mainly sand with a small fraction of pea gravel. We did not determine whether these eulachon spawned in that area or had congregated there for another purpose, such as holding or migration. Other species occasionally encountered in appreciable numbers were juvenile pink salmon Oncorhynchus gorbuscha and chum salmon O. keta. Mean in situ target strengths of eulachon were −53.3 dB at 123 kHz and −50.3 d...
Canadian Journal of Fisheries and Aquatic Sciences, 1984
Forest fertilization (435 kg urea∙ha−1) on the Mohun drainage, northern Vancouver Island, during ... more Forest fertilization (435 kg urea∙ha−1) on the Mohun drainage, northern Vancouver Island, during late fall 1979 resulted in a combined increase in urea, ammonia, and nitrate concentrations to 8000 μg N∙L−1 above control levels in streams not protected with 50-m-wide leave (i.e. unfertilized) strips and 350 μg N∙L−1 in those having leave strips. By spring 1980, dissolved nitrogen loads to Mohun Lake increased by a minimum of 55% in the largest basin and 1924% in the smallest basin. This corresponded to fertilizer losses of 2.1% of the total applied from drainages that had leave strips and up to 5.2% from those where the treatment included direct application to stream channels. Nitrogen transport was dominated by reduced nitrogen species and lasted up to 144 d. Relatively small changes in nitrate transport were attributed to low temperatures, which reduced rates of nitrification. Duringthe3-yr prior to forest fertilization, nitrogen and phosphorus were added to the lake at an N:P rati...
Canadian Journal of Fisheries and Aquatic Sciences, 1990
Nutrient concentrations, periphyton standing crop and size of steelhead trout (Oncorhynchus mykis... more Nutrient concentrations, periphyton standing crop and size of steelhead trout (Oncorhynchus mykiss) and coho salmon (O, kisutch) fry increased after the fertilization of a nutrient-deficient stream with inorganic phosphorus (P) and nitrogen (N). Whole-river fertilization of the Keogh River, British Columbia, during 1983–86 to increase summer average nutrient concentrations from < 1 μg P∙L−1 and 25 μg N∙L−1 to 10–15 μg P∙L−1 and 30–100 μg N∙L−1 resulted in five- to 10-fold increases in periphyton standing crops on artificial substrata and 1.4- to 2.0-fold increases in late-September salmonid fry weights. Diatoms and chlorophytes dominated the algal periphyton on artificial substrata at fertilized sites. Cyanophytes were unimportant despite low N:P ratios in some cases. Juvenile salmonids fed primarily on benthic insects. These results suggest that autochthonous primary production can be an important energy source in forested, middle-order streams, and indicate that the manipulatio...
Canadian Journal of Fisheries and Aquatic Sciences, 1987
Periphyton accumulation rates and alkaline phosphatase activity were examined in reaches of the K... more Periphyton accumulation rates and alkaline phosphatase activity were examined in reaches of the Keogh River, British Columbia, following additions of grain and inorganic fertilizer as separate treatments during spring–summer 1981. Two different levels of N and P addition were used: one to attain ambient N and P concentrations of 200 and 15 μg∙L−1, respectively, and the other to attain 400 and 20 μg∙L−1, respectively. Grain (rolled barley) was added monthly at 280 g∙m−2. N and P additions increased chlorophyll a accrual rates by more than an order of magnitude. Diatoms dominated the periphyton community until midsummer. In July and most of August, the relative importance of chlorophytes increased and biomass levels declined markedly in spite of continued nutrient additions. Grain additions resulted in no detectable change in periphyton accrual, but alkaline phosphatase activity increased by 35% over control levels. These results suggest that additions of labile organic matter to nutr...
Canadian Journal of Fisheries and Aquatic Sciences, 1994
Commercial formulations of the insecticidal bacterium Bacillus thuringiensis var. kurstaki (Btk) ... more Commercial formulations of the insecticidal bacterium Bacillus thuringiensis var. kurstaki (Btk) are frequently sprayed over bodies of water. The hypothesis that Btk poses a threat to stream communities was tested using streamside, flow-through mesocosms which received water and invertebrate colonists from a second-order stream in southwestern British Columbia; low (50 BIU/ha) and high (≥ 5000 BIU/ha) treatment levels were contrasted with controls. There were no significant differences in the density or composition of benthos sampled 7 d after Btk application. The densities were highest in the high-dose mesocosms. There were no significant differences in emergence rate of adults due to treatment. During the 2.5-h treatment, there were marginally elevated drift rates of the mayfly Baetis when exposed to the solution, but these differences were negated during the remainder of the 24-h period. Leaf packs lost significantly more mass in controls than in high-dose mesocosms, but there we...
Page 1. BULLETIN OF MARINE SCIENCE. 55(2-3): 1160-1180. 1994 DEBRIS STRUCTURE PLACEMENTS AND WHOL... more Page 1. BULLETIN OF MARINE SCIENCE. 55(2-3): 1160-1180. 1994 DEBRIS STRUCTURE PLACEMENTS AND WHOLE-RIVER FERTILIZATION FOR SALMONIDS IN A LARGE REGULATED STREAM IN BRITISH COLUMBIA ...
Transactions of the American Fisheries Society, 2003
... Transactions of the American Fisheries Society , 124: 857872. [Taylor &amp;amp; Francis ... more ... Transactions of the American Fisheries Society , 124: 857872. [Taylor &amp;amp; Francis Online], [Web of Science ®], [CSA] View all references). ... View all references; Desloges and Church 198910. Desloges, JR and Church, M. 1989. ...
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