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Changes in plasma cortisol concentrations and inter-renal and chromaffin tissues of rainbow trout, Oncorhynchus mykiss (Walbaum), exposed to harmful concentrations of the diatom Chaetoceros concavicornis were investigated. The plasma cortisol level of trout exposed to C. concavicornis was over 10-fold greater than that of untreated trout. Computer-assisted feulgen-microspectrophotometry was employed in order to assess the activity of inter-renal and chromaffin cells. The total areas of inter-renal and chromaffin nuclei in trout treated with C. concavicornis significantly increased compared to those of untreated fish. In contrast, the chromatin density of inter-renal and chromaffin nuclei in treated trout decreased significantly. This decrease of chromatin density in treated fish was caused by an increase in the low-density components, and a decrease in the middle-density and high-density components. Although the hypertrophic changes to the inter-renal and chromaffin nuclei of treated fish exhibited the same general trend, the extents to which the changes took place were different, occurring more rapidly within inter-renal tissues. The rainbow trout exposed to harmful concentrations of C. concavicornis were experiencing a severe physiological disturbance to which they tried to adapt.

Chaetoceros concavicornis is a harmful phytoplankter that occurs in many temperate coastal seawaters and can cause fin fish mortalities when present at concentrations as low as 5 cells∙mL−1. At even lower concentrations, this diatom can stress salmonids to such an extent that they may express a disease to which they are most prone at the time of C. concavicornis exposure. We report mortality rates of coho salmon (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) exposed to different concentrations of C. concavicornis. Our data indicate that in the presence of harmful concentrations of C. concavicornis, blood hematocrit and erythrocyte, glucose, and lactate concentrations of yearling chinook salmon (O. tshawytscha) increase. The microridges of the primary lamellae decreased in prominence in the presence of harmful concentrations of this phytoplankter, while the goblet cells became more prominent and more numerous. Neutrophil, lymphocyte, and thrombocyte concentrations in the blood became depleted. These data suggest that suppression of a portion of the Chinook's immune system is occurring which may partially explain the earlier observation that salmonids cultured in the presence of harmful C. concavicornis phytoplankton became more susceptible to disease, including Vibrio infections.

The harmful phytoplankters Chaetoceros concavicornis and Chaetoceros convolutus are normal components of the phytoplankton assemblage along the British Columbia coast. During 1988, these diatoms occurred at their highest concentrations in the spring and fall from the Strait of Georgia to Queen Charlotte Strait. North of Queen Charlotte Strait, the maximal concentrations appeared to be delayed until summer. The greatest concentrations occurred in the waters of the Strait of Georgia and its contiguous bays and inlets, especially Jervis Inlet, where concentrations of C. concavicornis and C. convolutus which could be harmful to salmon occurred during the spring and fall of 1988. Lesser concentrations occurred in coastal seawaters north of the Strait of Georgia. These phytoplankters were absent, or were present in only minor concentrations, in inlets with low-salinity waters such as Holberg Inlet and Indian Arm. Harmful Chaetoceros cells were restricted to seawaters greater than approximately 17‰ salinity. Vertically and horizontally well-mixed waters, such as those of Johnstone Strait, also appeared to restrict the presence of these cells. The greatest concentrations of these diatoms occurred during the spring and fall in relatively stratified coastal seawater with salinities between 26 and 34‰.

Development, growth, and survival data derived from laboratory experiments are provided for Lepeophtheirus salmonis, a common ectoparasite of wild and sea-farmed salmonids. The mean development time of eggs was 419·1 hours (17·5 days) at 5°C, 207·1 hours (8·6 days) at 10°C, and 130·8 hours (5·5 days) at 15°C. Development from the first nauplius to the infectious copepodid stage took 222·3 hours (9·3 days) at 5°C, 87·4 hours (3·6 days) at 10°C, and 44·8 (1·9 days) hours at 15°C. Development from the egg to the adult male took 40 days, and from the egg to the adult female 52 days at 10°C. No egg development occurred at 10‰ salinity. At 15‰ eggs developed but failed to produce active nauplii. At higher salinities (20–3‰) active nauplii were produced, but copepodids were only obtained at 30‰. Copepodids survived for less than 1 day in waters with a salinity of 10‰ or less. At higher salinities (15–30‰) and temperatures of 5,10, and 15°C average survival times ranged between 2 and 8 days.

Lepeophtheirus salmonis (Copepoda: Caligoida) is an economically important marine ectoparasite of wild and pen-reared salmonids. The morphology of its developmental stages is described and compared with that of other species of Lepeophtheirus and Caligus. The development of L. salmonis is very similar to that reported for other Lepeophtheirus species. The appendages generally attain the adult condition and the sexes become distinguishable later in development than in Caligus species. At all developmental stages except the nauplius, L. salmonis can be distinguished from the co-occurring Caligus clemensi.

Adults, preadults, and chalimus larvae of Lepeophtheirus cuneifer were recovered from rainbow trout, Oncorhynchus mykiss, and Atlantic salmon, Salmo salar, cultured in seawater in the southern Strait of Georgia, British Columbia. This species has not been reported previously from these hosts or in Canadian waters. It was found only in low abundance and is not an economically important parasite of farmed salmonids in British Columbia.

The water of a lake was sprayed with technical chlordane to give a concentration of approximately 10 ppb. Resident California newts (Tarichia torosa) and cutthroat trout (Salmo clarki) were subsequently collected and analyzed for residue concentrations. The newts were collected at 14, 279, 451, and 1,036 days; the trout at 93, 279, 421, and 1,014 days. At first, the concentrations of residues were very high in both species and their composition, except for heptachlor, resembled that of technical chlordane. The heptachlor was quantitatively epoxidized in news after 14 days but in trout, some heptachlor was still present after 93 days. Concentrations of total chlordane in body tissues of both species declined more than 98% with time. Of seven individually determined constituents of technical chlordane, trans-nonachlor was by far the most persistent, accounting for 49 to 55% of total chlordane in specimens collected last. Both animals produced oxychlordane, probably from gamma-chlordane. Heptachlor, heptachlor epoxide and gamma-chlordeine were non-detectable in both species after 279 days. The results strongly suggest that the California newt metabolizes and eliminates chlordane residues more effectively than the cutthroat trout.

Several marine waters and surface sediments of coastal British Columbia were analyzed and compared for bacterial colony forming units (CFU) and numbers of active bacteria (NAB) as indicated by microautoradiography, glucose and alanine heterotrophic activities, and dissolved (DOC) and particulate organic carbon (POC). Bacterial numbers (CFU, NAB) were usually much greater (by several orders of magnitude) in surface sediments than in overlying waters. DOC and POC were also generally greater in surface sediments than in overlying waters, often by as much as one order of magnitude. Both glucose and alanine heterotrophic potentials were greater in surface sediments; however, on a per active cell (NAB) basis, no significant differences were noted between the glucose-specific activities of the bacteria of the surface sediments and overlying waters. The data suggest that these surface sediments carry greater standing crops of bacteria than overlying waters without significant decreases in glucose-specific activities.

Annual cycles in the glucose heterotrophic potentials of the bacterioplankton of the lower Fraser River, its estuary and Georgia Strait surface waters were observed. Maximal microbial heterotrophic potentials were noted during the winter and early spring months, whereas maximal heterotrophic productivities were observed to occur during the summer and fall months. Temperature and soluble organic carbon levels appear to be the most important of the assayed physico-chemical parameters in regulating activities and productivities of the heterotrophic microbes of these waters.

Numbers of viable bacteria as indicated by colony-forming units (CFU), microbial adenosine triphosphate levels, dissolved organic carbon (DOC), particulate organic carbon and nitrogen (POC and PON), glucose concentration, heterotrophic potential (Vmax) and in situ heterotrophic activity (Vn) of near-surface microlayer samples (70–80 μm depth), the neuston, and bulk column water samples (0.2–1.5 m depth), the plankton, of several natural waters were compared. DOC and glucose concentration values of near-surface and bulk water were similar, whereas POC and PON values of the near-surface were normally one order of magnitude greater than those of bulk water. Viable counts were generally greater in the neuston, but ATP levels were greater in the plankton. Comparative values of total heterotrophic potentials and heterotrophic activities fluctuated greatly. Heterotrophic potential per CFU of the neuston was 33% of that of the plankton; neuston heterotrophic activity per CFU was 10% of that of the plankton. These data suggest that neustonic heterotrophic bacteria are not as metabolically active as their planktonic counterparts and that they are under greater stress at the near-surface than in the column water.

Periphytic and planktonic algal populations were sampled over a yearly cycle in the Ogilvie and Swift rivers located in the northern and southern Yukon, respectively. Diatoms and green algae dominated periphytic assemblages during spring, summer, and fall, whereas the bulk of the overwintering cells was diatoms. The 96 species of periphytic diatoms were dominated by Achnanthes minutissima Kütz., an unidentified species of Achnanthes, Cocconeis placentula Ehr., Diatoma hiemale var. mesodon (Ehr.) Grun., Diatoma tenue var. elongatum Lyngb., Anomoeoneis vitrea (Grun.) Ross, and Fragilaria crotonensis Kitton. Most diatoms encountered are also generally abundant in more temperate locations. Periphytic green algae were dominated by Mougeotia sp., Oedogonium sp., Ulothrix sp., and Stigeoclonium sp. In high flow regions of the Ogilvie River the red alga Lemanea fucina Bory was extremely abundant. Phytoplankton was sparse and generally represented by the same species as found in periphytic habitats. Results indicate that the phytoplankton cells were probably derived from sloughed periphytic cells. Achnanthes minutissima, Diatoma tenue var. elongatum, Fragilaria construens var. binodis (Ehr.) Grun., Fragilaria vaucheriae (Kütz.) Peters, and Synedra ulna (Nitz.) Ehr. were the most abundant species in the plankton.

Although the majority of the autochthonous heterotrophic bacterioplankton of the lower Fraser River appear to be killed when placed in Strait of Georgia marine water, their marine counterparts within Strait of Georgia surface water remain viable when treated with Fraser River water. However, within the plume water which naturally results when the freshwater of the Fraser River mixes with marine water of the Strait of Georgia, a stimulation in glucose heterotrophic activities occurs within the salinity range of approximately 3–18‰S. These increased bacterioplankton activities may be a consequence of a better nutrient environment within plume waters as compared to either parent water.

Seawater, marine surface sediment, fecal material of the sea cucumber Parastichopus californicus, and kelp blades of Macrocystis integrifolia were treated with formaldehyde to strengthen the bacterial cells, followed by tetrasodium pyrophosphate addition and sonication to disperse these same cells. These cells were then stained with 4′,6-diamidino-2-phenylindole and counted by epifluorescent microscopy. The technique of strengthening the cells with an aldehyde and then dispersing them in a suspending medium using a deflocculent (pyrophosphate) and ultrasound caused the bacteria to be randomly distributed when filtered onto Nuclepore membranes with a lower variance within and similar variance between subsamples as compared with untreated samples. In most cases the coefficient of variation stabilized after the bacterial cells in 10 randomly chosen microscopic fields had been counted. Sediment bacterial numbers (±SE) determined by the standard technique were 5.20 (±0.36) × 1010 per gram wet weight; by this dispersion technique they were 11.30 (±0.24) × 1011 per gram, a greater than twofold increase. On young and intermediate aged kelp blades, the increased counts which resulted from this dispersion technique ranged from two- to five-fold. Bacterial cells which were epiphytic on a senescent blade and could not be counted at all by the standard technique were determined to be 3.77 (±0.14) × 106 cm−2 using this dispersion method.

Most of the microorganisms within the silt-laden Fraser River water are bacteria, the majority of which are attached to detritus and suspended silt. However, within surface water of the Strait of Georgia bacteria constitute only about 4% of the microbial biomass; most are free-living. Within the plume, which results when the freshwater of the Fraser River mixes with the seawater of the Strait of Georgia (salinity of about 27‰ and containing mainly phytoplankton) stimulations of bacterial glucose heterotrophic activity and productivity occur throughout the year. Bacterial production is a relatively greater proportion of the total microbial, i.e. both algal and bacterial production, in the winter than in the spring or fall. Preliminary evidence indicates that the stimulation of bacterial activity and productivity may be, at least partially, due to entrainment of nitrate and phosphate-rich deep water of the Strait of Georgia into the Fraser plume.Key words: Fraser plume, bacteria, production, heterotrophic activity, Strait of Georgia

Water samples from the Fraser River and Georgia Strait, British Columbia were treated with different chlorinated hydrocarbons and incubated for up to 12 weeks at 13 C. 1) In the presence of bottom sediments from the same locations as the waters, no residues were found to escape into the atmosphere. 2) With the exception of lindane in ocean water, all detectable residues had moved into the sediments after 6 weeks. 3) Most of the lindane was metabolized. 4). Sterilization of the waters and sediments prevented the metabolism of lindane but had little effect on DDT and DDD. 5) Agitation of water samples containing γ-chlordane, incubated without sediment, had no effect on its disappearance, but the presence of 0.01% of a nonionic surfactant retarded this almost completely.

Water samples removed from two rivers and from the subtidal zone of Georgia Strait in British Columbia were treated with either 0.025 ppm of DDT, lindane, α-chlordane, or γ-chlordane, or 0.1 ppm Aroclor 1260 (PCB). The samples were incubated in the laboratory for up to 12 weeks at the temperatures of these natural waters at the time of sampling. Lindane persisted in all water samples throughout the experiment, but large proportions of the other compounds were transported into the atmosphere during incubation except when the containers were sealed. No metabolic breakdown could be demonstrated. As demonstrated with 14C-γ-chlordane, uneven distribution of the pesticides occurred rapidly, but was prevented, or reversed, by addition of a surfactant to the water. Total bacterial counts were generally higher in treated than in untreated water samples.

A fresh-water lake, free from detectable pesticide residues before this study, was treated with a commercial formulation of technical chlordane. Water and sediment samples were analysed for chlordane residues 7, 24, 52, 279. and 421 days after treatment. Residues moved rapidly from the water to the lake bottom, supporting earlier results of a laboratory study with other organochlorines. In water, alpha- and gamma-chlordane concentrations remained proportional to total chlordane concentrations, as determined by total-peak area measurements of gas-liquid chromatogrammes. But in bottom sediments, alpha- and gamma-chlordane were more persistent than other constituents of technical chlordane, supporting recent evidence that quantification of technical chlordane residues on the basis of gamma-chlordane quantification only (or that of alpha- and gamma-chlordane only), can lead to incorrect results and that this method, although simple and fast, should no longer be recommended.

Between August 1972 and September 1973, fish, crabs, and shellfish were collected from the lower Fraser River, its estuary, and selected areas of Georgia Strait in British Columbia. Samples were analyzed for aldrin, dieldrin, alpha- and gamma-chlordane, p,p'-DDT, p,p'-DDE, p,p'-DDD, heptachlor, heptachlor epoxide, lindane, and polychlorinated biphenyls (PCB's). Of these, p,p'-DDT, p,p'-DDE, p,p'-DDD, heptachlor epoxide, and one PCB, Aroclor 1254, were detected in samples of many fish, crabs, and shellfish from the lower Fraser River and its estuary. Generally, compounds found in decreasing order of magnitude in samples from the Fraser River and its estuary were: PCB's, p,p'-DDE, heptachlor epoxide, p,p'-DDT, and p,p'-DDD. Greatest concentrations of these compounds occurred in biota from the waters adjacent to the City of Vancouver. With one exception, animals from Georgia Strait and those away from the immediate influence of Fraser River water contained no detectable levels of chlorinated hydrocarbons.

Increasing amounts of high-specific-activity tritiated organic compounds were added to samples of several natural waters such that in situ substrate concentrations might be approximated. The uptake responses by the native heterotrophic microflora suggested that (i) heterotrophic populations metabolize the added nutrients, but (ii) these responses are not necessarily a reflection of Michaelis-Menten enzyme kinetics. The uptake kinetics appeared to be due to dilution of the naturally occurring metabolite by added radioactive substrate and physiological responses of the microflora to organic enrichment.