Effects of temperature and pH on the growth, calcification, and biomechanics of two species of articulated coralline algae

Abstract

Ocean warming and acidification are predicted to impact the physiology of marine organisms, especially marine calcifiers that must deposit calcium carbonate and resist dissolution. Of particular concern are articulated coralline algae, which must maintain both calcified segments (intergenicula) and uncalcified joints (genicula) in order to thrive along wave-swept rocky coastlines. We examined the effect of pH and temperature, both individually and in combination, on the growth, calcification, and biomechanical properties of 2 species of articulated coralline algae, Corallina vancouveriensis and Calliarthron tuberculosum, common on wave-exposed shores in the NE Pacific. Increased temperature and reduced pH were found to reduce growth rates in both species (30-89% lower) but had little influence on the amount of intergenicular calcium carbonate or on the genicular biomechanical properties of these species. Results suggest that although growth rates may decline, these 2 coralline species will maintain the integrity of their tissues and continue to persist under future climate stress.

Interactive effects of temperature and nitrogen on the physiology of kelps (Nereocystis luetkeana and Saccharina latissima)

“…We manipulated seawater temperatures and nutrient concentrations using 100 L (91 x 34 x 30 cm; L x W x H) recirculating tanks in the FHL Ocean Acidification Environmental Laboratory (O'Donnell et al, 2013;Guenther et al, 2022). Natural seawater was UV-sterilized to deter phytoplankton and diatom growth prior to starting experiments.…”

“…were slightly lower to mimic relatively cooler conditions likely experienced by S. latissima in the understory of a stratified water column. We manipulated temperatures in each tank following the methods in O' Donnell et al (2013) and Guenther et al (2022) and measured temperature ( ± 0.1°C) with HOBO Pendant Temperature/Light Data Loggers (Onset model #MX2202, Bourne, MA) every 5 min. We slowly changed temperatures (by 2°C per day) over 5 days until final treatment temperatures were reached (Figure S1).…”

Kelp and sea urchin settlement mediated by biotic interactions with benthic coralline algal species

“…Specifically, we examined red sea urchin ( Mesocentrotus franciscanus ) metamorphosis rates and the settlement of the two largest canopy kelps, the giant kelp ( Macrocystis pyrifera ) and bull kelp ( Nereocystis luetkeana ), and the subcanopy five‐ribbed kelp ( Costaria costata ) in the presence of several coralline algal species. Given the vulnerability of coralline algae to ocean acidification and warming (Cornwall et al., 2019; Guenther et al., 2022), understanding the ecological services provided by coralline algae and their influence on kelp forest dynamics is becoming increasingly important.…”