title: Oxygenation of anoxic sediments triggers hatching of zooplankton eggs.
abstract: Many coastal marine systems have extensive areas with anoxic sediments and it is not well known how these conditions affect the benthic-pelagic coupling. Zooplankton lay their eggs in the pelagic zone, and some sink and lie dormant in the sediment, before hatched zooplankton return to the water column. In this study, we investigated how oxygenation of long-term anoxic sediments affects the hatching frequency of dormant zooplankton eggs. Anoxic sediments from the brackish Baltic Sea were sampled and incubated for 26 days with constant aeration whereby, the sediment surface and the overlying water were turned oxic. Newly hatched rotifers and copepod nauplii (juveniles) were observed after 5 and 8 days, respectively. Approximately 1.5 × 10(5) nauplii m(-2) emerged from sediment turned oxic compared with 0.02 × 10(5) m(-2) from controls maintained anoxic. This study demonstrated that re-oxygenation of anoxic sediments activated a large pool of buried zooplankton eggs, strengthening the benthic-pelagic coupling of the system. Modelling of the studied anoxic zone suggested that a substantial part of the pelagic copepod population can derive from hatching of dormant eggs. We suggest that this process should be included in future studies to understand population dynamics and carbon flows in marine pelagic systems.
authors.affiliation: Centre for Ecology and Evolution in Microbial model Systems (EEMiS), Linnaeus University, Kalmar, Sweden elias.broman@lnu.se.
authors.forename: Elias
authors.initials: E
authors.lastname: Broman
authors.affiliation: Centre for Ecology and Evolution in Microbial model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Brüsin
authors.affiliation: Centre for Ecology and Evolution in Microbial model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
authors.forename: Mark
authors.initials: M
authors.lastname: Dopson
authors.affiliation: Centre for Ecology and Evolution in Microbial model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
authors.forename: Samuel
authors.initials: S
authors.lastname: Hylander
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D033342:Copepoda / Q000254:growth & development*; D019015:Geologic Sediments / Q000737:chemistry*; D009792:Oceans and Seas; D010063:Ovum / Q000254:growth & development; D010100:Oxygen / Q000378:metabolism*; D012403:Rotifera / Q000254:growth & development*; D000068357:Saline Waters / Q000737:chemistry*; D015048:Zooplankton / Q000254:growth & development
chemical_list: D010100:Oxygen
keywords: Acartia; anoxia; diapause; eggs; hatching; sediment