Search results for "Zooplankton"

Coexistence of cryptic rotifer species: ecological and genetic characterisation of Brachionus plicatilis

2003

SUMMARY 1. The coexistence of five cryptic species of the rotifer species complex Brachionus plicatilis was investigated in four coastal Mediterranean ponds. Monthly sampling was undertaken for 15 months and species were characterised using allozyme electrophoresis. 2. We describe species-diagnostic allozyme loci that can be used for rapid identification of these species. 3. The five species overlapped to some extent in their temporal use of the ponds, although some seasonal segregation was observed. 4. The match between temporal and spatial distribution and limnological conditions suggested ecological specialisation in some cases, although we found striking examples of extensive seasonal o…

Predatory interactions between a cyclopoid copepod and three sibling rotifer species

2002

SUMMARY 1. Cyclopoid copepod predation on rotifers affects the dynamics and structure of zooplankton communities. We address the differential vulnerability of three sympatric rotifer sibling species belonging to the Brachionus plicatilis species complex. These co-occur with their cyclopoid predator, Diacyclops bicuspidatus odessanus. 2. Using video recording and tracking, we analysed the steps in predation including attack distance, attack angle, and rotifer species swimming in the presence and absence of the predator. Our results show the greater vulnerability of B. rotundiformis (the smallest species) to D. b. odessanus predation, which is associated with a high percentage of attacks afte…

Zooplankton dynamics during autumn circulation in a small, wind-sheltered, Mediterranean lake

2006

12 pages, and tables statistics.

Pseudo-diel vertical migration in zooplankton: a whole-lake 15N tracer experiment

2012

Diel vertical migration (DVM) of zooplankton is commonly considered an adaptation for feeding in food-rich and warm surface waters at night and avoiding visual predators during the day. However, the critical assessment of migration patterns frequently suggests that: (i) zooplankton may leave deeper waters with rich, deepchlorophyll layers and move into the epilimnion where food resources are lower and/or (ii) the night-time increase in epilimnetic plankton abundance is not matched by a density decrease in deeper strata. To study these discrepancies, we measured DVM of zooplankton in a 1.3-ha Spanish karst lake (Laguna del Tejo) where the phytoplankton in the deep chlorophyll layer had been …

Estado trofico y distribucion del plancton estival de 8 lagos chilenos (32° - 41° S)

2009

Latvijas ūdeņu vides pētījumi un aizsardzība: Latvijas Universitātes 69. zinātniskās konferences LU Bioloģijas fakultātes Hidrobioloģijas katedras se…

2011

Krājumā ievietotie referātu kopsavilkumi nav recenzēti un rediģēti.

On the occurrence of Eudiaptomus gracilis (G.O. Sars, 1863) (Copepoda: Diaptomidae) in Madeira (Portugal)

2020

Calanoid copepods belonging to the diaptomid genus Eudiaptomus Kiefer, 1932 were collected in an artificial water body on the island of Madeira, Portugal. The morphological and molecular identification of the collected specimens unequivocally proved that they belong to the allochthonous species Eudiaptomus gracilis (G. O. Sars, 1863), possibly unwarily introduced along with fish stockings or ornamental aquatic plants. In the sampled site, the species co-occurred with the non-native cyclopoid copepod Acanthocyclops americanus (Marsh, 1893) and some anomopod species. This is the first record of the species for Portugal and the whole Macaronesia, whereas the possible presence of E. gracilis in…

Variation in zooplankton diets in contrasting small lakes, inferred from stable isotope analyses

2007

Response of a shallow Mediterranean lake to nutrient diversion: does it follow similar patterns as in northern shallow lakes?

2005

Summary 1. In view of the paucity of data on the response of warm shallow lakes to reductions in nutrient loading, this paper presents a long-term limnological data set to document changes in the food-web of a shallow Mediterranean lake (Lake Albufera, Valencia, Spain) that has experienced reductions in phosphorus (P) (77%) and nitrogen (N) (24%) loading following sewage diversion. 2. Nine years after sewage diversion, P concentration in the lake was reduced by 30% but remained high (TP = 0.34 mg L−1), although the mean water retention time in the lake was only 0.1 years. Nitrate concentrations did not significantly change, probably because the lake continued to receive untreated effluents …

Food sources and lipid retention of zooplankton in subarctic ponds

2011

SUMMARY 1. Subarctic ponds are seasonal aquatic habitats subject to short summers but often have surprisingly numerous planktonic consumers relative to phytoplankton productivity. Because subarctic ponds have low pelagic productivity but a high biomass of benthic algae, we hypothesised that benthic mats provide a complementary and important food source for the zooplankton. To test this, we used a combination of fatty acid and stable isotope analyses to evaluate the nutritional content of benthic and pelagic food and their contributions to the diets of crustacean zooplankton in 10 Finnish subarctic ponds. 2. Benthic mats and seston differed significantly in total lipids, with seston (62.5 l …