Survival, Reproduction and Calcification of Three Benthic Foraminiferal Species in Response to Experimentally Induced Hypoxia

Research areas:
Year:
2014
Keywords:
Anoxia, Benthic foraminifera, Biogeosciences, Environmental {Monitoring/Analysis}, Freshwater {&} Marine Ecology, growth, Hypoxia, Reproduction, Survival rate
Authors:
Editor:
Kitazato, Hiroshi and Bernhard, Joan M.
Volume:
ajout_vol
Chapter:
ajout_chap
Pages:
163{\textendash}193
Publisher:
Springer Japan
Address:
ajout_ville
Series:
Environmental Science and Engineering
JRESEARCH_TYPE_F:
16
Edition:
ajout_edit
Month:
January
ISBN:
978-4-431-54387-9, 978-4-431-543
Note:
<p>ajout_notes</p>
Abstract:
<p>An experiment was conducted to test the survival rates, growth (calcification), and reproduction capacities of three benthic foraminiferal species (Ammonia tepida, Melonis barleeanus and Bulimina marginata) under strongly oxygen-depleted conditions alternating with short periods of anoxia. Protocols were determined to use accurate methods (1) to follow oxygen concentrations in the aquaria (continuously recorded using microsensors), (2) to distinguish live foraminifera (fluorogenic probe), (3) to determine foraminiferal growth (calcein-marked shells and automatic measurement of the shell size). Our results show a very high survival rate, and growth of A. tepida and M. barleeanus in all experimental conditions, suggesting that survival and growth are not negatively impacted by hypoxia. Unfortunately, no reproduction was observed for these species, so that we cannot draw firm conclusions on their ability to reproduce under hypoxic/anoxic conditions. The survival rates of Bulimina marginata are much lower than for the other two species. In the oxic treatments, the presence of juveniles is indicative of reproductive events, which can explain an important part of the mortality. The absence of juveniles in the hypoxic/anoxic treatments could indicate that these conditions inhibit reproduction. Alternatively, the perceived absence of juveniles could also be due to the fact that the juveniles resulting from reproduction (causing similar mortality rates as in the oxic treatments) were not able to calcify, and remained at a propagule stage. Additional experiments are needed to distinguish these two options.</p>
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