Growth and reproduction of Macoma balthica (L.) on a mud flat in the Fraser River estuary, British Columbia

1983 ◽  
Vol 61 (4) ◽  
pp. 887-894 ◽  
Author(s):  
E. R. McGreer
Keyword(s):  
Growth Rate ◽  
British Columbia ◽  
Shell Height ◽  
Macoma Balthica ◽  
River Estuary ◽  
Dry Weight ◽  
Maximum Growth ◽  
Fraser River ◽  
Mud Flat ◽  
Growth And Reproduction

Growth and reproduction of the bivalve, Macoma balthica (Linnaeus, 1758) was studied for one year (April 1977 – March 1978) on an intertidal mud flat in the Fraser River estuary, British Columbia. The maximum number of individuals (1830/m2) occurred in April, then steadily declined throughout the year. Spawning occurred between mid-June and late July but recruitment was slow and prolonged. Peak spatfall (age 0+ individuals) did not occur until the following March when a maximum density of only 410/m2 for newly settled spat was observed. The oldest animals found were 5+ years of age. Maximum growth took place from April through July. The growth rate measured was one of the highest recorded for any M. balthica population. A direct relationship between high water temperatures, a fast growth rate, and reduced longevity was apparent. A regression of body weight on shell height was used to calculate a condition factor (CF), which reached its highest value during growth and its lowest value immediately after spawning. The mean annual biomass measured was 2.96 g dry weight per square metre.

Diet and feeding of Neomysis mercedis Holmes (Crustacea, Mysidacea) from the Fraser River Estuary, British Columbia

1982 ◽  
Vol 60 (5) ◽  
pp. 813-824 ◽  
Author(s):  
N. T. Johnston ◽  
D. C. Lasenby
Keyword(s):  
Body Size ◽  
Consumption Rate ◽  
Ingestion Rate ◽  
River Estuary ◽  
Dry Weight ◽  
Fraser River ◽  
Organic Fraction ◽  
Biological Origin ◽  
Seasonal Differences ◽  
Harpacticoid Copepods

Neomysis mercedis in the Fraser River estuary is a predator on the meiobenthos, especially harpacticoid copepods. There are no clear seasonal differences in its utilization of food resources. The consumption rate of N. mercedis feeding from natural sediments varies with body size and temperature as C = 3.81 W0.782T0.515, where C is the consumption rate of meiofauna in micrograms dry weight per animal per hour, W is the mysid size in milligrams dry weight, and T is the temperature in degrees Celsius. The weight dependence of the ingestion rate is identical to that of the metabolic rate but the temperature dependence is significantly lower. The mysid selectively feeds on the organic fraction of the sediments but only one-half of the ingested material (by weight) is of biological origin. In mid-April, mysid predation may result in a 12% per day mortality rate on harpacticoid copepods. Thus, mysid predation may strongly influence meiofaunal densities.

Uptake of Selected Organochlorine Contaminants in Fishes Resident in the Fraser River Estuary, Vancouver, British Columbia

1992 ◽  
Vol 27 (4) ◽  
pp. 733-750 ◽  
Author(s):  
I.H. Rogers ◽  
J.S. Macdonald ◽  
M. Sadar
Keyword(s):  
British Columbia ◽  
Food Chain ◽  
River Estuary ◽  
Control Fish ◽  
Fraser River ◽  
The North ◽  
Organochlorine Contaminants

Abstract Starry flounders, prickly sculpins and other resident fishes were captured in the Lower Fraser River in the summers of 1987, 1988 and 1989. Control fish were taken from the estuary of the uncontaminated Homathko River on the B.C. coast in 1987 and 1988. The fish were analysed for chlorophenols, chloroguaiacols and PCBs. The residues most commonly detected were PCBs, tetra-and pentachlorophenol. Fish from the Main Arm contained PCBs that resembled Arochlor 1248 whereas those from the North Arm contained PCBs that resembled a mixture of Arochlors 1254 and 1260. Chloroguaiacol uptake was greater in flounders than in other species. Although PCBs appear to have declined markedly in the Lower Fraser from values published in the early 1970s, there is a need to measure the coplanar fraction to understand their toxic significance to the food chain. Tetra- and pentachlorophenol have declined following a change by industry to the use of alternative sapstain prevention treatments.

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