Seasonal size variation in the predatory cladoceran Bythotrephes cederstroemii in Lake Michigan
نویسندگان
چکیده
1. Dry weight, body length and spine length were measured for the exotic cladoceran Bythotrephes cederstroemii collected from offshore and inshore stations in southeastem Lake Michigan. Average dry weight of each developmental stage exhibited seasonal variation by a factor of more than 5. 2. Mean dry weight of Bythotrephes was closely correlated with water temperature. Contrary to the inverse relationship between water temperature and body size frequently observed for other invertebrates, the dry weight of Bythotrephes increased at higher ambient temperatures. 3. No significant correlation was observed between abundances of major zooplankton taxa and the dry weight of Bythotrephes. An indirect effect of temperature on prey consumption may cause seasonal variation in dry weight of Bythotrephes in Lake Michigan. 4. Distances between adjacent pairs of barbs, added to the caudal spine with each moult, are significantly shorter in Bythotrephes which produce resting eggs. Less material investment in the exoskeleton of sexually reproducing females was observed in favour of growth and reproduction.
منابع مشابه
Diet composition from allozyme analysis in the predatory cladoceran Bythotrephes cederstroemi
Investigating diet composition with visual analyses of gut contents requires that the predator consume recognizable hard parts. Soft tissue remains of prey in the gut of the predatory cladoceran Bythotrephes cederstroemi were identified with cellulose acetate electrophoresis. We found that B. cederstroemi collected from an offshore station in Lake Michigan had fed on cyclopoid and Calanoid cope...
متن کاملEpilimnetic rotifer community responses to Bythotrephes longimanus invasion in Canadian Shield lakes
We studied whether the effects of Bythotrephes longimanus, a new predatory cladoceran zooplankton species to North America, can extend beyond the macrozooplankton to the rotifer community, which is known to be an important controller of the microbial loop. During summer 2003, 14 Canadian Shield lakes were sampled biweekly to evaluate the effect of Bythotrephes on epilimnetic rotifers. Rotifer d...
متن کاملEffects of the non-indigenous cladoceran Cercopagis pengoi on the lower food web of Lake Ontario
1. In North America, the invasive predatory cladoceran Cercopagis pengoi was first detected in Lake Ontario. We explored the impact of Cercopagis on the lower food web of Lake Ontario through assessments of historical and seasonal abundance of the crustacean zooplankton, by conducting feeding experiments on the dominant prey of the invader, and by estimating its food requirements. 2. Between 19...
متن کاملSeasonal zooplankton dynamics in Lake Michigan: Disentangling impacts of resourcelimitation, ecosystem engineering, and predation during a criticalecosystem transition
Seasonal zooplankton dynamics in Lake Michigan: Disentangling impacts of resource limitation, ecosystem engineering, and predation during a critical ecosystem transition" (2012). a b s t r a c t a r t i c l e i n f o We examined seasonal dynamics of zooplankton at an offshore station in Lake Michigan from 1994 to 2003 and 2007 to 2008. This period saw variable weather, declines in planktivorous...
متن کاملZooplankton life cycles: Direct documentation of pelagic births and deaths relative to diapausing egg production
Zooplankton demographics operate over multiple time scales corresponding to pelagic parthenogenetic generations, an overwintering stage, and an ‘‘egg bank.’’ Comparisons of pelagic birth and death rates with seasonal diapausing egg production provide insights into local species persistence. The spiny cladoceran (Bythotrephes) possesses morphological adaptations (spines and thick-walled diapausi...
متن کامل