Sensitivity of sea urchin fertilization to pH varies across a natural pH mosaic.
In the coastal ocean, temporal fluctuations in pH vary dramatically across biogeographic ranges. How such spatial differences in pH variability regimes might shape ocean acidification resistance in marine species remains unknown. We assessed the pH sensitivity of the sea urchinStrongylocentrotus purpuratusin the context of ocean pH variability. Using unique male-female pairs, originating from three sites with similar mean pH but different variability and frequency of low pH (pHT≤ 7.8) exposures, fertilization was tested across a range of pH (pHT7.61-8.03) and sperm concentrations. High fertilization success was maintained at low pH via a slight right shift in the fertilization function across sperm concentration. This pH effect differed by site. Urchins from the site with the narrowest pH variability regime exhibited the greatest pH sensitivity. At this site, mechanistic fertilization dynamics models support a decrease in sperm-egg interaction rate with decreasing pH. The site differences in pH sensitivity build upon recent evidence of local pH adaptation inS. purpuratusand highlight the need to incorporate environmental variability in the study of global change biology.
Department of Ecology Evolution and Marine Biology University of California Santa Barbara Santa Barbara CA USA; Sorbonne Universités Université Pierre et Marie Curie-Paris 6 CNRS-INSU Laboratoire d'Océanographie de Villefranche Villefranche-sur-Mer France.
Lydia
0000-0002-7361-9061
L
Kapsenberg
Department of Ecology Evolution and Marine Biology University of California Santa Barbara Santa Barbara CA USA; School of Resource and Environmental Management Simon Fraser University Burnaby BC Canada.
Daniel K
DK
Okamoto
Wrigley Institute for Environmental Studies University of Southern California Los Angeles CA USA.
Jessica M
JM
Dutton
Department of Ecology Evolution and Marine Biology University of California Santa Barbara Santa Barbara CA USA.
Gretchen E
GE
Hofmann
Strongylocentrotus; adaptive capacity; fertilization; ocean acidification; pH variability; sea urchin