Publication Date:
2024-04-11
Description:
Sea urchins as broadcasting spawners, release their gametes into open water for fertilization,
thus being particularly vulnerable to ocean acidification. In this study, we assessed
the effects of different pH scenarios on fertilization success of Strongylocen-
5 trotus droebachiensis, collected at Spitsbergen, Arctic. We achieved acidification by
bubbling CO2 into filtered seawater using partial pressures (pCO2) of 180, 380, 980,
1400 and 3000 μatm. Untreated filtered seawater was used as control. We recorded
fertilization rates and diagnosed morphological aberrations after post-fertilization periods
of 1 h and 3 h under different exposure conditions in experiments with and without
10 pre-incubation of the eggs prior to fertilization. In parallel, we conducted measurements
of intracellular pH changes using BCECF/AM in unfertilized eggs exposed to a range
of acidified seawater. We observed increasing rates of polyspermy in relation to higher
seawater pCO2, which might be due to failures in the formation of the fertilization envelope.
In addition, our experiments showed anomalies in fertilized eggs: incomplete
15 lifting-off of the fertilization envelope and blebs of the hyaline layer. Other drastic malformations
consisted of constriction, extrusion, vacuolization or degeneration (observed
as a gradient from the cortex to the central region of the cell) of the egg cytoplasm,
and irregular cell divisions until 2- to 4-cell stages. The intracellular pH (pHi) decreased
significantly from 1400 μatm on. All results indicate a decreasing fertilization success
20 at CO2 concentrations from 1400 μatm upwards. Exposure time to low pH might be
a threatening factor for the cellular buffer capacity, viability, and development after fertilization.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
peerRev
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