The effects of in-vitro pH decrease on the gametogenesis of the red tree coral, Primnoa pacifica.

Area of Science:

• Marine Biology
• Oceanography
• Climate Change Research

Background:

• Primnoa pacifica is a vital coral species in the North Pacific, offering critical habitat for marine life.
• High-latitude oceans experience accelerated ocean acidification due to increased CO2 absorption in colder waters.
• Ocean acidification poses a significant threat to marine ecosystems and commercially important species.

Purpose of the Study:

• To investigate the effects of predicted ocean acidification levels on the gametogenesis of Primnoa pacifica.
• To assess the impact of reduced pH on oocyte development, fecundity, and spermatocyst stages in this key coral species.

Main Methods:

• Primnoa pacifica colonies were cultured for 6-9 months under two pH conditions: pH 7.55 (Year 2100 prediction) and pH 7.75 (control).
• Oocyte development (size, fecundity, oosorption) in females and spermatocyst development in males were measured.
• Statistical analyses were performed to determine the effects of pH and laboratory conditions on gametogenesis.

Main Results:

• Oocyte diameter decreased by 13.6% and fecundity by 30.9% in the lower pH (7.55) treatment.
• A higher rate of oocyte reabsorption (oosorption) was observed in corals exposed to predicted future ocean pH.
• Lower pH appeared to accelerate spermatogenesis, though a laboratory effect also influenced these results.

Conclusions:

• Ocean acidification significantly impairs oogenesis in Primnoa pacifica, indicated by smaller oocytes and increased oosorption.
• Reduced gamete quality and quantity suggest that successful spawning may be unlikely under future acidified ocean conditions.
• The findings highlight the vulnerability of this ecologically important coral to climate change, with potential cascading effects on associated fish and invertebrate populations.