Latin American & Caribbean Aquaculture 2025

October 7 - 9, 2025

Puerto Varas, Chile

Add To Calendar 09/10/2025 11:40:0009/10/2025 12:00:00America/GogotaLatin American & Caribbean Aquaculture 2025CO-CULTURING MACROALGAE AND BIVALVES AS A STRATEGY TO MITIGATE OCEAN ACIDIFICATION AND ENHANCE BIOMASS YIELDSTronadorThe World Aquaculture Societyjohnc@was.orgfalseDD/MM/YYYYanrl65yqlzh3g1q0dme13067

CO-CULTURING MACROALGAE AND BIVALVES AS A STRATEGY TO MITIGATE OCEAN ACIDIFICATION AND ENHANCE BIOMASS YIELDS

Pablo Leal*, Daniela Uribe, Karla Álvarez

Laboratorio de Ambientes y Recursos Marinos (ARMlab), Departamento de Repoblación y Cultivo, Instituto de Fomento Pesquero

J. M. Balmaceda 252, Puerto Montt, Chile

pablo.leal@ifop.cl



Photosynthesis can buffer ocean acidification (OA) by raising seawater pH, favouring calcification. Thus, incorporating macroalgae into bivalve farms may help mitigate OA impacts, while also enhancing biomass production. We present two laboratory experiments addressing this potential.

 First, we evaluated the effect of the  blue  mussel Mytilus chilensis and three macroalgae (Ulva sp., Chondracanthus chamissoi , Macrocystis pyrifera) on seawater chemistry in mono- and co-cultures under ambient and OA conditions. Macroalgal monocultures increased pH and aragonite saturation state (Ωara) compared to mussel monoculture, while co-cultures showed intermediate values. A daytime buffering effect (pH > 7.7, Ωara > 1) occurred in co-cultures, while nighttime conditions remained unfavourable for calcification (Fig. 1).

Second, we assessed optimal initial biomass ratios in four macroalga–bivalve combinations (C. chamissoi:Magallana gigas , Sarcopeltis skottsbergii:M. gigas , C. chamissoi:M. chilensis , Gracilaria chilensis:M. chilensis) over 28–30 days using the De Wit replacement series. A synergistic interaction emerged, with 2:1 (macroalga:bivalve) as the optimal ratio (Fig. 2) , driven by the faster growth  rates of macroalgae (2–8 times greater than that of bivalves.

These results indicate that macroalgae can enhance biomass production in co-cultures but do not guarantee favourable calcification conditions under OA. Further long-term (>30 days) studies in laboratory and field settings are needed to assess co-culture benefits fully.