Errors in the estimation of recruitment of early stages of mesocyclops leuckarti (claus) caused by the diurnal periodicity of egg-production

Abstract

The seasonal and bathymetrical distribution of Mesocyclops leuckarti (Claus) was investigated during 1969-1975. Development time of egg, naupliar and copepodite stages were found experimentally at three temperatures (15° 22°and 27°C) . The calculations of population dynamics generated some unexplained results .Experimental study of the influence of light-dark conditions and temperature on the process of laying and hatching, together with the field data, helped us to describe an artifact when sampling is done at early morning .

Diel changes in the egg production rate of Acartia tonsa (Copepoda, Calanoida) and related environmental factors in two estuaries

“…Duval & Geen 1976, Stearns 1986, with cyclic egg production the resulting by-product of cyclic changes in ingested food available for such production. Gophen (1978) explained higher egg production by Mesocyclops leuckarti in constant darkness than in alternated light and dark periods as the result of higher feeding activity in darkness, with a time lag of ca 1 d between feeding and subsequent egg production within the experimental temperature range (22 to 27 "C). We found Acartia tonsa to be both a nocturnal grazer and a nocturnal egg layer (Figs.…”

“…reviews by Cushing 1951 andBainbridge 1961) and daily feeding (Stearns 1986 and references therein), diel egg laying by copepod zooplankters is a shortinterval, cyclic behavior that is sparsely documented. Although few copepod species have been tested specifically for such behavior, it is becoming clear that dramatic changes in egg production can occur on a time scale of hours (Harding et al 1951, Marshall & Orr 1952, Mullin 1968, Spindler 1971, Valentin 1972, Gophen 1978, Saint-Jean & Pagano 1983, Marcus 1985, Runge 1985. If diel egg laying behavior is common, it would have important consequences for ecological theory dealing with secondary production in aquatic systems, because present production coefficients of models do not reflect short-term changes in egg production rate.…”

The swimming and feeding behavior of Mesocyclops

“…edax.• Woodmansee & Grantham, 1961 ;Wyngaard, 1978 ;Wright et al, 1980 ;Williamson & Magnien, 1982; M. hyalinus (Rehberg) : Worthington & Ricardo, 1936 as cited by Woodmansee & Grantham, 1961 ;M. leuckarti: Worthington, 1931 ;Einsle, 1968 ;Begg, 1976;Gophen, 1978) . Migrations are generally more pronounced in the adult and larger copepodite stages of Mesocyclops while the nauplii migrate little if at all (M. edax.• Williamson & Magnien, 1982;M.…”

“…The planktonic nature of copepods of this genus is notable among the generally littoral/benthic cyclopoids . In subtropical populations Mesocyclops may remain active in the plankton throughout the year (Gophen, 1972(Gophen, , 1978Twombly, 1983) . In most temperate and arctic systems Mesocyclops is active in the plankton only during the warmer months of the year and undergoes diapause in the sediments in an unencysted late copepodite stage during the winter months (see review in Vijverberg, 1977) .…”

The productivity of mesocyclops leuckrarti (Claus) in Lake Kinneret (Israel)

“…Studies on the influence of temperature on development, feeding and excretion of M. leuckarti in Lake Kinneret have been previously published (Gophen, 1976a ;1977a ;1977b) . In the present study, growth, productivity, feeding and respiration are considered.…”