Dataset: Performance of coral and sea anemone early life stages under normoxic and hypoxic conditions from lab and field experiments performed in Pennsylvania (USA) and Bermuda in 2023-2024

Adult culture and spawning

Adult Nematostella vectensis sea anemones were collected from a salt marsh in Brigantine, New Jersey in the fall of 2020, and spawning was induced. Larvae (n = 1 cohort with mixed parentage) were then cultured to the planula stage (3 d post-fertilization) for experimentation. An aquarium population of adult Galaxea fascicularis colonies (n = 9 females, 10 males) spawned during August 2023 at Carnegie Science (Baltimore, MD, USA), yielding a cohort of planulae (n = 1 cohort with mixed parentage) that were used in experiments within 48 h. Adult Porites astreoides colones (n = 20) were collected in Bermuda (32°22′13″N, 64°44′27″W) during July 2023. Brooded planulae (n = 4 cohorts) were collected and maintained in culture for ~ 48 h.

At the time of use in experimentation, larvae from all 3 species were in the planula stage and would become competent to settle within 72–96 h (Hand and Uhlinger 1992; Goodbody-Gringley et al. 2018; Wei et al. 2023). Artificial seawater was used for culturing and experimentation for N. vectensis and G. fascicularis, while flow-through, natural seawater facilities at the Bermuda Institute for Ocean Science were used for P. astreoides.

Dissoved Oxygen Treatments

Stage-matched, swimming planulae of N. vectensis, G. fascicularis, and P. astreoides (N = 1,200–2,400 larvae species-1) were divided into six replicate groups (three normoxia/control and three hypoxia) and exposed to 6 h of normoxia (dissolved oxygen (DO) = 6.8–8.69 mg L-1) or severe hypoxia (DO = 1.58–1.8 mg L-1; seawater deoxygenated using N2 gas) inside sealed glass jars (500 mL) overnight from 21:00 h to 03:00 h the following day. The jars were placed at the ambient culture temperature for each species (N. vectensis: 18°C; G. fascicularis: 27°C; P. astreoides: 28°C). At the end of the treatment period, the jars were uncapped and groups of 20–30 larvae (N = 60–90 larvae treatment-1 species-1) were transferred to 1.5 mL tubes without seawater for storage at -80°C until processing

Measurements

Detailed methods can be found in the associated publication (Glass and Barott 2025).

• Ash-free dry weight (AFDW; i.e., organic biomass) of larvae and juveniles was quantified from burned, dried tissue.
• Chlorophyll content within algal endosymbionts of larvae and juveniles was quantified via spectroscopy.
• Heat tolerance of P. astreoides larval symbionts was quantified via changes in photochemical yield (collected with a pulse-amplitude-modulation (PAM) fluorometer) over time at 36°C.
• Heat tolerance of larvae was quantified via visual observation of survival over time at 36°C. Photochemical yield of P. astreoides larvae and juveniles as quantified using a pulse-amplitude-modulation (PAM) fluorometer.
• Metabolic rates of larvae and juveniles was quantified via respirometry.
• Protein content larvae and juveniles was quantified via Bradford assays.
• Larval settlement rates were quantified via brightfield microscopy.
• Larval and juvenile sizes were quantified via brightfield microscopy.
• Larval swimming behavior immediately following the oxygen treatments was quantified via imaging using iPhone 14 (Apple).
• Larval and juvenile symbiont density was quantified via flow cytometry.