Measurement of Egg Production Rate of Calanus finmarchicus from Preserved Samples

1987 ◽  
Vol 44 (11) ◽  
pp. 2009-2012 ◽  
Author(s):  
Jeffrey A. Runge

A method for determining Calanus egg production rates from preserved, net-tow samples is proposed. In the sea off Nova Scotia, in situ egg production rates (eggs per female per day) of Calanus finmarchicus are significantly related to an index of gonadal development in preserved females. This relationship could be used in combination with data on female abundance to estimate daily production of eggs in the water column. The method is illustrated with data from a transect across Browns Bank.

2019 ◽  
Vol 41 (5) ◽  
pp. 741-758 ◽  
Author(s):  
Josephine GrØnning ◽  
Nam X Doan ◽  
Nguyet T Dinh ◽  
Khuong V Dinh ◽  
Torkel Gissel Nielsen

ABSTRACT The calanoid copepod Pseudodiaptomus annandalei is used as live feed in aquaculture because of its nutritional value and the ability to cope with environmental fluctuations in outdoor ponds. However, little knowledge exists on its ecology. Here we investigated the ecology of P. annandalei in an aquaculture pond in Vietnam. Temperature, salinity, chlorophyll a and biomass of protozoans and copepods were monitored every other day for 1 month. Experiments on protozoan growth and grazing by P. annandalei were also conducted. Copepod fecal pellet production and temperature-dependent egg hatching rates were likewise quantified. Despite very high phytoplankton biomass, biomass of P. annandalei was surprisingly low. Copepod production was estimated from three independent methods: clearance, weight-specific egg production rate (SEP) and specific fecal pellet production rate. SEP proved to be accurate to predict the in situ population growth in the pond. A simple model for production of P. annandalei based on SEP was developed. Our study extends our knowledge of how environmental conditions in the pond may affect the population dynamics and production of copepods. The results have important implications for pond managements ensuring stable copepod production and harvest.


2001 ◽  
Vol 58 (4) ◽  
pp. 647-658 ◽  
Author(s):  
Stéphane Plourde ◽  
Pierre Joly ◽  
Jeffrey A Runge ◽  
Bruno Zakardjian ◽  
Julian J Dodson

The life cycle of Calanus finmarchicus in the lower St. Lawrence estuary is described based on observations of female egg production rate, population stage abundance, and chlorophyll a biomass collected over 7 years (1991–1997) at a centrally located monitoring station. The mean seasonal pattern shows maximum abundance of females in May, but peak population egg production rate and naupliar (N3–N6) abundance occur in early July just after onset of the late spring – early summer phytoplankton bloom. The population stage structure is characterized by low summer abundance of early copepodite stages C1–C3 and high stage C5 abundance in autumn. Between 1994 and 1997, there was important interannual variation in both timing (up to 1 month) and amplitude (five- to eight-fold) of population reproduction. Patterns of seasonal increase of C5 abundance in autumn suggest interannual variations of both timing and magnitude of deep upstream advection of this overwintering stage. Thus, the main features of C. finmarchicus population dynamics in the central lower St. Lawrence Estuary are (i) late reproduction resulting from food limitation prior to the onset of the summer phytoplankton bloom, (ii) probable export of early developmental stages during summer, and (iii) advection into the central lower St. Lawrence Estuary of overwintering stage C5 in autumn from downstream regions. These results support the hypothesis that circulation, mainly driven by discharge from the St. Lawrence River and its tributaries, is a key factor governing population dynamics of C. finmarchicus in this region.


2000 ◽  
Vol 57 (3) ◽  
pp. 518-529 ◽  
Author(s):  
Robert W Campbell ◽  
Erica JH Head

Egg production rates of Calanus finmarchicus were measured in the Labrador Sea (spring) and on the Scotian Shelf (spring, summer, and autumn), in conjunction with indices of gonad maturity and food availability, female body size, surface layer temperature, and surface nitrate concentrations. Egg production rates were often two to four times higher than any previously reported at similar temperatures. Estimates of egg production rates of populations were most closely related to the proportion of reproductively mature females (as measured by a gonad stage index) and female size. Specifically, the gonad stage index (proportion of females capable of spawning) was correlated with the proportion of females that spawned during 24-h incubations, and female size determined the clutch size (i.e., number of eggs produced). Although there were detectable effects of food and temperature on egg production rates, they were generally weaker than the effect of female gonad maturity. Thus, over the broad spatial and temporal scales of this study, the reproductive (i.e., life history) status of a population was more important in determining its egg production rate than direct external factors (i.e., temperature and food conditions).


1997 ◽  
Vol 54 (6) ◽  
pp. 1270-1279 ◽  
Author(s):  
J Cabal ◽  
L R Harris ◽  
EJH Head

Egg production rates and population characteristics of Calanus finmarchicus were examined in the Labrador Sea during the spring of 1994. Several experiments were conducted in order to compare egg production rates and clutch size using different types of container and in the presence and absence of food. In one series of experiments, individual females were incubated either in petri dishes or in polycarbonate bottles (80 mL) in filtered seawater. In these experiments, clutch sizes and egg production rates were not significantly different. In a second series of experiments, groups of 20 females were placed in containers under three sets of conditions: in the presence of food and with a screen to separate copepods from their eggs (FSCREEN), in the presence of food without a screen (FOOD), and in filtered seawater without a screen (FSW). Average egg production rates of female C. finmarchicus were significantly higher in the FSCREEN treatments than in either of the other two. In these experiments, egg production rates were not obviously related to ingestion rates, and these in vitro observations together with observations of in situ conditions suggest that stored reserves may have been used to fuel, or supplement, reproduction in C. finmarchicus in this area.


1948 ◽  
Vol 27 (6) ◽  
pp. 719-726 ◽  
Author(s):  
Wilbor O. Wilson

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