Thesis Defense by Noah Kolander – May 5th

"Abalone and seaweed co-culture: growth and shell biomineralization of an iconic California gastropod"

A Thesis Defense by Noah Kolander

MLML Phycology

Live-Stream | May 5th, 2025 at 4:00 pm PDT

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Abstract

Climate change threatens shellfish aquaculture worldwide, with ocean acidification (OA) accelerating shell dissolution and reducing calcification, hindering growth. This study addressed the negative impacts of OA on juvenile red abalone (Haliotis rufescens), a life stage that is particularly susceptible to climate stressors, and the ability of the red seaweed, dulse (Devaleraea mollis), to mitigate these effects. I tested the hypothesis that Integrated Multi-Trophic Aquaculture (IMTA), with abalone and seaweed grown in co-culture, can raise seawater pH through photosynthesis to yield more favorable conditions for abalone growth and shell construction. A 5-month experiment was conducted to determine the benefits of IMTA on abalone growth, shell composition, and morphology under simulated ocean acidification conditions. In each tank, 620 abalone were raised in either High (8.1 ± 0.3), Ambient (7.9 ± 0.2), Medium (7.8 ± 0.3), or Low pH (7.6 ± 0.2). Abalone raised in High and Ambient pH treatments exhibited greater shell length, weight, area, and condition compared to those raised in medium and low pH treatments. Shell analyses indicated that these growth differences translate into differences in physical and chemical properties, with shells from the high and ambient pH treatments containing higher levels of Mg2+ and being more resistant to fracturing. These findings indicate that IMTA could shepherd abalone through the susceptible juvenile stage, increasing resilience of abalone aquaculture even within the context of future climate change.
Bio
I grew up in a little town called Wildomar in Southern California with 3 brothers, my mom and dad. I eventually went off to college at Concordia University where I quickly reignited my passion for marine science after volunteering in our campus marine lab that Sean Bigniami had just finished building the year before I got there. From there on, I was diving, doing research and presenting at conferences, studying pismo clam distributions in Southern California, and eventually conducting an abalone feed trial to determine if preserving their food by freezing or drying it affected abalone growth. I quickly got married after graduation and moved to Miami for my wife to finish her DPT program. While she studied, I worked for the Florida Department of Health and the Department of Agriculture. WHen Steff finished her degree she didn't think twice before asking me where I wanted to go to school next, which at the time was not on my radar, but she convinced me and it was the best choice she'd ever make for me! I then found MLML and applied under Maya deVries and got in. While at MLML, I have worked on too many projects to name, which is partially to blame for my extended stay at MLML, but I wouldn't trade it for anything. I wouldn't trade the friends I've made and the times I;ve had for anything. Thank you all for the support you have given me and for putting up with me.

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