Li, S., Zhang, G.
J. Ocean. Limnol. 39, 609–622 (2021). doi:10.1007/s00343-020-0071-0
Role of intraspecific competition in intrinsic growth rate regulation in an Oikopleura dioica (Tunicata) population.
“Individuals of Oikopleura dioica (Tunicata, Appendicularia) were collected in the Jiaozhou Bay, Qingdao, China (35°03′N, 120°20′E) on June 20, 2017, using a plankton net with a large-volume cod-end (10L). The samples were diluted into 50 L buckets and transported immediately to the laboratory, where healthy individuals were sorted and cultured in a small room (approximately 10 m2) maintained at 18 ± 1°C using a standard air conditioner.”
“parental animals were forced to release their gametes by gentle aspiration in a pipette. Then, all dishes were placed in a speed-regulating vibrator (HY-4H) rotating at 60 r/min for 5 min to mix the eggs and male gametes together, and this time was considered time zero (D0).”
“To control the food concentration, a mono-diet of Isochrysis galbana was adopted for all treatments.”
“From gamete production, the entire incubation duration was 4 d and 12 h.”
“The body length of O. dioica was 145 ± 17 μm on average after 15 h of metamorphosis.” “ On average, body lengths of 324–549 μm were achieved at the end of the experiments.” “At each food level, both the final body and gonad length decreased on average with density.”
“Calculated with a fixed generation duration of 4.5 d, the mean maximal intrinsic rate of natural increase (rmax) varied between 0.25 and 0.65/d”
“In general, the population growth was significantly regulated by the PFS. The rmax was increased with the PFS and was saturated at values higher than 8.1 μg C/ind.”
“Though the mortality recorded in our experiments was generally higher at low food concentrations, it is uncertain whether mortality increased with increased competition stress.”