Update on the IMARCS Foundation's Mission and Current Research Programs
The International Marine Science and Carbon Sequestration (IMARCS) Foundation is dedicated to advancing marine science through innovative research and conservation initiatives focused on the health and resilience of coral reef ecosystems. Our work centers on the protection and restoration of vital reef species — including giant clams, corals, and mangroves — and their crucial roles in supporting biodiversity and coastal communities.
We are pioneering novel, science-based solutions to reverse coral bleaching, enhance reef restoration, and explore the untapped potential of nature-based carbon storage within giant clam shells. Through collaborative research and actionable conservation strategies, the IMARCS Foundation strives to positively impact our oceans, our atmosphere, and the well-being of people on land who are ultimately affected by what happens in the sea and in the air.
The IMARCS Foundation has launched three initial complementary research programs to harness the ecological and biogeochemical potential of giant clams within coral reef systems. All projects draw on multidisciplinary expertise—ranging from marine ecology to molecular genetics and biogeochemistry—to generate actionable insights for reef restoration, climate mitigation, and ecosystem resilience. These three initial experiments all leverage the unique biology of giant clams (Tridacnidae) to address three of today’s most pressing marine challenges: reversing coral bleaching, restoring reef habitats, and exploring novel nature-based carbon sequestration pathways. By integrating field experiments, molecular assays, and biogeochemical monitoring, we aim to generate reproducible, scalable solutions for reef resilience in a warming world.
Novel Research Study #1: Coral bleaching restoration
Our first experiment, based in Micronesia, is evaluating whether introducing giant‐clam–derived Symbiodiniaceae (zooxanthellae) into bleached corals can accelerate symbiont recolonization and photosynthetic recovery. Coral bleaching—driven by the breakdown of the coral–algal symbiosis under heat stress—has become more frequent and severe over the past four decades (Hoegh-Guldberg & Bruno, 2010). Building on findings that clam‐expelled symbionts remain viable and infective (Morishima et al., 2019; Umeki et al., 2020), we are currently collecting tissue samples from corals that have been dosed with zooxanthellae isolated from Tridacna clams to see if this can have a positive effect on corals. Over the next three months, all samples will be processed at our lab at the University of Barcelona to quantify symbiont species, density, chlorophyll fluorescence, and host stress markers, allowing us to determine whether clam‐sourced zooxanthellae confer enhanced thermal tolerance compared to native coral strains and if this can accelerate the recovery of thermally stressed corals.
We are pioneering novel, science-based solutions to reverse coral bleaching, enhance reef restoration, and explore the untapped potential of nature-based carbon storage within giant clam shells. Through collaborative research and actionable conservation strategies, the IMARCS Foundation strives to positively impact our oceans, our atmosphere, and the well-being of people on land who are ultimately affected by what happens in the sea and in the air.
The IMARCS Foundation has launched three initial complementary research programs to harness the ecological and biogeochemical potential of giant clams within coral reef systems. All projects draw on multidisciplinary expertise—ranging from marine ecology to molecular genetics and biogeochemistry—to generate actionable insights for reef restoration, climate mitigation, and ecosystem resilience. These three initial experiments all leverage the unique biology of giant clams (Tridacnidae) to address three of today’s most pressing marine challenges: reversing coral bleaching, restoring reef habitats, and exploring novel nature-based carbon sequestration pathways. By integrating field experiments, molecular assays, and biogeochemical monitoring, we aim to generate reproducible, scalable solutions for reef resilience in a warming world.
Novel Research Study #1: Coral bleaching restoration
Our first experiment, based in Micronesia, is evaluating whether introducing giant‐clam–derived Symbiodiniaceae (zooxanthellae) into bleached corals can accelerate symbiont recolonization and photosynthetic recovery. Coral bleaching—driven by the breakdown of the coral–algal symbiosis under heat stress—has become more frequent and severe over the past four decades (Hoegh-Guldberg & Bruno, 2010). Building on findings that clam‐expelled symbionts remain viable and infective (Morishima et al., 2019; Umeki et al., 2020), we are currently collecting tissue samples from corals that have been dosed with zooxanthellae isolated from Tridacna clams to see if this can have a positive effect on corals. Over the next three months, all samples will be processed at our lab at the University of Barcelona to quantify symbiont species, density, chlorophyll fluorescence, and host stress markers, allowing us to determine whether clam‐sourced zooxanthellae confer enhanced thermal tolerance compared to native coral strains and if this can accelerate the recovery of thermally stressed corals.
Image Credits - https://www.the-scientist.com/a-probiotic-to-protect-caribbean-corals-71204
Novel Research Study #2: Reef restoration in Nha Trang
In Nha Trang Bay, Vietnam, near Hon Tre Island, our second study investigates habitat enhancement via giant clam reintroduction. Reef degradation in Southeast Asia has led to a >50% loss of live coral cover since the 1980s (Spurgeon, 1992). We have now transplanted over 50 Tridacna squamosa and T. crocea at densities of ~10 individuals per 10m transect onto denuded reef substrata. Over the next 8–12 months, we will use environmental DNA (eDNA) metabarcoding to track shifts in community composition of not only macro species but also cryptic invertebrates, bacterial consortia, and fish larvae. By comparing pre- and post-reintroduction eDNA profiles, we expect to detect increases in habitat complexity, filter-feeder abundance, and microbial diversity—key indicators of ecosystem recovery.
Novel Research Study #3: CO2 storage in elevated pH tanks
Our third project explores whether manipulated mariculture conditions can turn giant clams into bona fide carbon sinks. Under ambient seawater chemistry, shell formation in clams and other calcifiers is approximately carbon-neutral, as the CO₂ released during CaCO₃ precipitation offsets the carbon sequestered. We hypothesize that elevating pH to ≥8.5—within the range of tropical reef flats (Price et al., 2012)—will shift the carbonate system toward greater CO₂ uptake. In our southern Japan mariculture facility, two 10 m³ tanks are fully instrumented: one maintained at ambient pH (~8.2), the other at elevated pH (~8.5–9.0), both at ~28 °C. Continuous dissolved inorganic carbon (DIC) and total alkalinity (TA) monitoring, combined with clam growth measurements (shell height, dry weight) and shell δ¹³C analysis, will allow us to calculate net ecosystem calcification (NEC) and CO₂ flux. Once our high-precision pH and CO₂ sensors are able to be implemented, we will introduce Tridacna derasa juveniles and monitor their shell accretion and carbon budget at 3, 6, 9, and 12 months.
Novel Research Study #2: Reef restoration in Nha Trang
In Nha Trang Bay, Vietnam, near Hon Tre Island, our second study investigates habitat enhancement via giant clam reintroduction. Reef degradation in Southeast Asia has led to a >50% loss of live coral cover since the 1980s (Spurgeon, 1992). We have now transplanted over 50 Tridacna squamosa and T. crocea at densities of ~10 individuals per 10m transect onto denuded reef substrata. Over the next 8–12 months, we will use environmental DNA (eDNA) metabarcoding to track shifts in community composition of not only macro species but also cryptic invertebrates, bacterial consortia, and fish larvae. By comparing pre- and post-reintroduction eDNA profiles, we expect to detect increases in habitat complexity, filter-feeder abundance, and microbial diversity—key indicators of ecosystem recovery.
Novel Research Study #3: CO2 storage in elevated pH tanks
Our third project explores whether manipulated mariculture conditions can turn giant clams into bona fide carbon sinks. Under ambient seawater chemistry, shell formation in clams and other calcifiers is approximately carbon-neutral, as the CO₂ released during CaCO₃ precipitation offsets the carbon sequestered. We hypothesize that elevating pH to ≥8.5—within the range of tropical reef flats (Price et al., 2012)—will shift the carbonate system toward greater CO₂ uptake. In our southern Japan mariculture facility, two 10 m³ tanks are fully instrumented: one maintained at ambient pH (~8.2), the other at elevated pH (~8.5–9.0), both at ~28 °C. Continuous dissolved inorganic carbon (DIC) and total alkalinity (TA) monitoring, combined with clam growth measurements (shell height, dry weight) and shell δ¹³C analysis, will allow us to calculate net ecosystem calcification (NEC) and CO₂ flux. Once our high-precision pH and CO₂ sensors are able to be implemented, we will introduce Tridacna derasa juveniles and monitor their shell accretion and carbon budget at 3, 6, 9, and 12 months.
Image Credits - https://phys.org/news/2020-07-giant-clams-symbiotic-partner.html
Our ongoing commitment to marine science and useable research
Beyond these three core experiments, IMARCS is collaborating with local stakeholders—Micronesian clam farms, Vietnamese researchers, and Japanese aquaculture research institutes—to ensure that our findings translate into policy and practice. For example, if clam-sourced symbionts prove more resilient, restoration practitioners could develop protocols for mass-culturing specific zooxanthellae strains that could contribute to the reversal of coral bleaching. Similarly, positive eDNA signals in Vietnam may justify large-scale clam nurseries as a low-tech reef-rehabilitation tool. Finally, demonstrating net negative carbon flux in pH-elevated tanks could open a new front in blue carbon strategies, positioning giant clam farms as certified offset generators under voluntary and compliance markets.
The IMARCS Foundation’s integrated approach—melding genetics, ecology, and geochemistry—reflects a paradigm shift in reef conservation: moving from passive protection to active, science-driven restoration and mitigation. As climate change and coastal development continue to stress reefs, harnessing the natural capacities of keystone species like giant clams offers both ecological and socio-economic dividends. We anticipate publishing our first peer-reviewed results in late 2025, and we invite colleagues and practitioners to engage with our open-access data portal on our Current Research page to foster collaborative innovation in reef resilience.
Image Credits - https://drawdown.org/solutions/seafloor-protection
References:
Hoegh-Guldberg, O., & Bruno, J. F. (2010). The impact of climate change on the world’s marine ecosystems. Science, 328(5985), 1523–1528.
Ikeda, S., Yamashita, H., Kondo, S., Inoue, K., Morishima, S., & Koike, K. (2017). Zooxanthellal genetic varieties in giant clams are partially determined by species-intrinsic and growth-related characteristics. PLoS ONE, 12(2), e0172285.
Morishima, S., Yamashita, H., O-hara, S., Nakamura, Y., Quek, V. Z., Yamauchi, M., & Koike, K. (2019). Study on expelled but viable zooxanthellae from giant clams, with an emphasis on their potential as subsequent symbiont sources. PLoS ONE, 14(7), e0220141.
Price, N. N., Martz, T. R., Brainard, R. E., & Smith, J. E. (2012). Diel variability in seawater pH relates to calcification and benthic community structure on coral reefs. PLOS ONE, 7(8), e43843.
Spurgeon, J. P. G. (1992). The economic valuation of coral reefs. Marine Pollution Bulletin, 24(11), 529–536.
Thomsen, P. F., & Willerslev, E. (2015). Environmental DNA – An emerging tool in conservation for monitoring past and present biodiversity. Biological Conservation, 183, 4–18.
Umeki, M., Yamashita, H., Suzuki, G., Sato, T., Ohara, S., & Koike, K. (2020). Fecal pellets of giant clams as a route for transporting Symbiodiniaceae to corals. PLoS ONE, 15(12), e0243087.
Ikeda, S., Yamashita, H., Kondo, S., Inoue, K., Morishima, S., & Koike, K. (2017). Zooxanthellal genetic varieties in giant clams are partially determined by species-intrinsic and growth-related characteristics. PLoS ONE, 12(2), e0172285.
Morishima, S., Yamashita, H., O-hara, S., Nakamura, Y., Quek, V. Z., Yamauchi, M., & Koike, K. (2019). Study on expelled but viable zooxanthellae from giant clams, with an emphasis on their potential as subsequent symbiont sources. PLoS ONE, 14(7), e0220141.
Price, N. N., Martz, T. R., Brainard, R. E., & Smith, J. E. (2012). Diel variability in seawater pH relates to calcification and benthic community structure on coral reefs. PLOS ONE, 7(8), e43843.
Spurgeon, J. P. G. (1992). The economic valuation of coral reefs. Marine Pollution Bulletin, 24(11), 529–536.
Thomsen, P. F., & Willerslev, E. (2015). Environmental DNA – An emerging tool in conservation for monitoring past and present biodiversity. Biological Conservation, 183, 4–18.
Umeki, M., Yamashita, H., Suzuki, G., Sato, T., Ohara, S., & Koike, K. (2020). Fecal pellets of giant clams as a route for transporting Symbiodiniaceae to corals. PLoS ONE, 15(12), e0243087.