Background
The authors say that "due to global change, marine gametes and fertilization are experiencing increased seawater temperature and acidification." And, therefore, they felt it important to determine what the consequences of this two-pronged phenomenon might be for the Antarctic echinoid Sterechinus neumayeri, their choice of this species being due to the fact that "polar marine organisms are among the most stenothermal in the world due to the stability of their environment over evolutionary time (Clarke, 1983)," which would tend to suggest that they would be "sensitive to the slightest of environmental perturbations, particularly life history stages (Barnes and Peck, 2008)."

What was done
As described by Ho et al., "the impact of increased temperature (2-4°C above ambient) and decreased pH (0.2-0.4 pH units below ambient) on fertilization in the Antarctic echinoid Sterechinus neumayeri across a range of sperm concentrations was investigated in cross-factorial experiments," where "gametes from multiple males and females in replicate experiments were used to reflect the multiple spawner scenario in nature."

What was learned
The five researchers' work confirmed "the importance of considering both ocean warming and acidification," noting that "decreased pH did not affect fertilization" but that "warming enhanced fertilization ... likely through stimulation of sperm motility and reduced water viscosity."

What it means
As expressed in the concluding sentence of their paper's abstract, Ho et al. state that their results indicate that "fertilization in S. neumayeri, even at low sperm levels potentially found in nature, is resilient to near-future ocean warming and acidification."

References
Barnes, D.K.A. and Peck, L.S. 2008. Vulnerability of Antarctic shelf biodiversity to predicted regional warming. Climate Research 37: 149-163.

Clarke, A. 1983. Life in cold water, the physiological ecology of polar marine ectotherms. Oceanography and Marine Biology: An Annual Review 21: 341-453.