Feeding rates of planktonic copepods from inshore waters, near Townsville, north Queensland

Brief description

Laboratory experiments were carried out to investigate the feeding rates of 5 species of tropical planktonic copepods. Calanopia elliptica, Eucalanus subcrassus, Paracalanus aculeatus, Tortanus gracilis and Temora turbinata were selected from plankton samples collected from inshore waters near Townsville, from May to October, 1976. Seawater was also collected from the sampling sites and filtered for use in experiments.Prior to commencement of experiments, subsamples of copepods were taken for dry body weight measurements. Experiments commenced 3-4 hours after collection. Individual Eucalanus, Tortanus or Calanopia were placed in 50 or 75 ml beakers of filtered seawater and 20 to 50 Artemia nauplii were added. Beakers were placed in a glass incubator so that the copepods were subjected to natural light cycles. Temperatures were maintained close to that of the water where the copepods were collected (22-25°C). To examine differences in feeding rates between day and night, each copepod was removed and placed in a new beaker, under the same conditions, twice a day (0800 and 1700hr) until the copepod died. Artemia nauplii remaining in the beaker after removal of the copepod were counted and the feeding rate calculated. The effect of container volume on feeding rates was also tested by placing single females of Eucalanus subcrassus or Tortanus gracilis in containers of different volumes (50, 200, 1000 ml).Experiments with Temora turbinata and Paracalanus aculeotus were carried out in 24.5 ml vials instead of beakers and each copepod was removed and placed in a new vial once per day. The concentration of the phytoplankton food cells introduced to each copepod was between 1-3 x 10^6 µm³/ml. Incubations were carried out in the dark to prevent cell sedimentation and addition growth of food cells. The concentration of cells prior to and after incubations were determined in terms of total cell volume with a Coulter Counter TAII.The experimental results were used to calculate daily ration for each copepod species, expressed as a percentage of body weight. This research was initiated to 1. measure feeding rates of copepods from tropical waters2. enable comparisons with published feeding rates of copepods from temperate and boreal seas. Food species:Eucalanus, Tortanus and Calanopa: newly hatched Artemia naupliiTemora: Dunaliella salina Paracalanus: Skeletonema costatum

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Statement: Collection methods:Planktonic copepods were collected using a 100 cm diameter, 202 µm mesh net fitted with a 5 litre canvas bag at the cod end.Number and sex of copepods used:Eucalanus subcrassus: 17 female, 6 maleTortanus gracilis: 12 female, 3 maleCalanopia elliptica: 6 female, 4 maleTemora turbinata: 10 femaleParacalanus aculeatus: 9 female

Notes

Credit
Ikeda, Tsutomu, Dr (Principal Investigator)