Life history characteristics and distribution of Bythotrephes longimanus Leydig (Crustacea, Onychopoda) in the Biesbosch reservoirs

Abstract

The diel and horizontal distributions of Bythotrephes longimanus Leydig, Leptodora kindti (Focke) and Anomopoda (cladocerans), as well as several life history parameters of each developmental stage of B. longimanus were studied in the non-stratified Biesbosch reservoirs . Anomopoda avoided the surface layer during the day only in the pelagic zone . In the surface layer near the shore, however, they were very abundant . Because densities in the pelagic zone during the day were very low, and high during the night, the population undoubtedly moved from the littoral zone or from the sediments to the pelagic . Accumulation of zooplankton at the littoral site is either the result of random dispersal or wind-induced movements . Bythotrephes' diel distribution pattern is possibly related to that of their prey, the anomopods . Leptodora mostly exhibited a `normal' diel vertical migration with a small amplitude . Wind most likely influenced the horizontal distribution of the zooplankton . Bythotrephes body length increased with higher temperatures, whereas spine length was constant throughout the year . Bythotrephes can already be fertile in the first developmental stage, indicating that a rapid adaptation to a favourable environment is possible . The number of parthenogenetically produced eggs per ovigerous female was higher at the start of the growing season and constant throughout the rest of the year . Relatively few resting eggs and males were found in autumn .

Dynamics of the invasive spiny water flea, Bythotrephes longimanus, in Lake Simcoe, Ontario, Canada

“…In most years, however, parthenogenic clutch size was lowest in August, ranging from ~2 to 3 embryos per clutch. Similar parthenogenic clutch sizes in summer have been observed previously for Bythotrephes in Harp Lake (Young 2008), Lake Michigan (Pothoven et al 2001(Pothoven et al , 2003, and European lakes (Straile and Halbich 2000) and reservoirs (Ketelaars et al 1995). Resting eggs are typically produced at the end of the Bythotrephes seasonal cycle (Yurista 1992), and in Lake Simcoe occurred in the fall in most years, but they were also observed to occur in spring and summer in some years.…”

“…The increase in Bythotrephes body length in July and August observed in some years may be related to higher epilimnetic temperatures elevating Bythotrephes food consumption (Burkhardt 1994, Ketelaars et al 1995, Yurista et al 2010. In all years, mean epilimnetic temperatures increased from 10 °C in May to 20-22 °C by August.…”

“…Seasonal fluctuations in Bythotrephes body length across instars were evident in most years, possibly the result of the interplay between temperature, availability of prey, and predation by planktivorous fish (Ketelaars et al 1995). The increase in Bythotrephes body length in July and August observed in some years may be related to higher epilimnetic temperatures elevating Bythotrephes food consumption (Burkhardt 1994, Ketelaars et al 1995, Yurista et al 2010.…”

Role of diapause in dispersal and invasion success by aquatic invertebrates

“…Probability for gamogenetic female of such strain carrying resting eggs to be pumped into ships' ballast tank during most period of population development is much higher than for the strains possessing "normal" life-cycle with comparatively short period of sexual reproduction in the autumn. "Normal" life-cycle recorded for introduced population of Bythotrephes longimanus in the reservoir in the Netherlands (Ketelaars et al 1995), and in case of Daphnia lumholtzi invasion in North America, may support this hypothesis possibly demonstrating case studies of dispersal of "normal strains". Fast erosion of this phenomenon in Bythotrephes in Harp Lake and Cercopagis in Neva Estuary most likely related to fast evolution of the life cycle of invading species under strong press from invader-selective fish predation: by lake herring Coregonus artedii in Harp Lake (Coulas et al 1998) and by the Baltic herring Clupea harengus membras in the Gulf of Finland (Antsulevich & Väli-pakka 2000).…”

“…However, the study of life history traits of Bythotrephes in Biesbosch Reservoirs did not show any changes in the mode of reproduction. Few males and gamogenetic females were observed in the end of the summer season (Ketelaars et al 1995).…”