17:15 〜 19:15
[AOS14-P01] Isolated Culture and Evaluation of the Light Response Focusing on Polyp Morphological Changes of Corals for the Establishment of a Space Marine Ecosystem
キーワード：サンゴ、海洋生態系、宇宙海洋
In the current solar system, the presence of liquid water on the surface is a unique characteristic of planet Earth and is considered essential for the birth and survival of "terrestrial-type" life. However, the Moon lacks an atmosphere, and Mars has only a thin atmosphere—its atmospheric pressure is merely 0.75% that of Earth (101.3 kilopascals)—making the existence of liquid water impossible under normal conditions. Constructing an ocean outside of Earth may only be feasible in small-scale aquatic environments using limited water resources. Thus, establishing small-scale marine ecosystems with primary producers such as coral reefs and seagrass beds, similar to coastal ecosystems on Earth, becomes crucial.
The objective of this study is to establish a long-term stable culture of corals on land as a mini-core biome in an isolated environment away from the ocean. This serves as a foundation for developing small-scale marine ecosystems in space environments with limited resources, such as the Moon and Mars.
For the coral culturing environment, we used the natural coral reef ecosystem of Okinawa, one of the world's most prominent coral reef regions, as a reference. Field surveys and environmental analyses were conducted to examine long-term coral culturing in tanks composed of minimal elements, using artificial seawater that replicated the environmental characteristics of the Okinawa region.
Field surveys and seawater sampling were carried out around Iriomote Island, Okinawa Prefecture. Three coral species—Porites cylindrica, Acropora intermedia, and Acropora tenuis—were successfully cultured for two months in an aquarium system without natural seawater, by maintaining water quality equivalent to that of the collected seawater samples. All three coral species exhibited an increase in weight over the two-month period, indicating their adaptability to an aquarium system without natural seawater.
In experiments with varying light intensities, different morphological changes were observed. Specifically, Porites cylindrica showed an effect on polyp opening at low light intensity, while Acropora intermedia and Acropora tenuis exhibited color changes and polyp extensions, respectively. These findings suggest that corals undergo morphological changes in response to environmental shifts, with variations depending on the species.
In general, Acropora species are considered vulnerable to environmental changes, particularly temperatures exceeding 29 degrees Celsius. However, our study demonstrates that with careful temperature control, Acropora species remain highly resistant to other environmental fluctuations, such as changes in light conditions.
For marine ecosystems in space—such as those on the Moon and Mars—where water resources are scarce and monitoring coral conditions is challenging, our results suggest that it may be possible to construct small-scale marine ecosystems using at least these three coral species. By focusing on their morphological changes, we can better understand their conditions and optimize their survival in extraterrestrial environments.
The objective of this study is to establish a long-term stable culture of corals on land as a mini-core biome in an isolated environment away from the ocean. This serves as a foundation for developing small-scale marine ecosystems in space environments with limited resources, such as the Moon and Mars.
For the coral culturing environment, we used the natural coral reef ecosystem of Okinawa, one of the world's most prominent coral reef regions, as a reference. Field surveys and environmental analyses were conducted to examine long-term coral culturing in tanks composed of minimal elements, using artificial seawater that replicated the environmental characteristics of the Okinawa region.
Field surveys and seawater sampling were carried out around Iriomote Island, Okinawa Prefecture. Three coral species—Porites cylindrica, Acropora intermedia, and Acropora tenuis—were successfully cultured for two months in an aquarium system without natural seawater, by maintaining water quality equivalent to that of the collected seawater samples. All three coral species exhibited an increase in weight over the two-month period, indicating their adaptability to an aquarium system without natural seawater.
In experiments with varying light intensities, different morphological changes were observed. Specifically, Porites cylindrica showed an effect on polyp opening at low light intensity, while Acropora intermedia and Acropora tenuis exhibited color changes and polyp extensions, respectively. These findings suggest that corals undergo morphological changes in response to environmental shifts, with variations depending on the species.
In general, Acropora species are considered vulnerable to environmental changes, particularly temperatures exceeding 29 degrees Celsius. However, our study demonstrates that with careful temperature control, Acropora species remain highly resistant to other environmental fluctuations, such as changes in light conditions.
For marine ecosystems in space—such as those on the Moon and Mars—where water resources are scarce and monitoring coral conditions is challenging, our results suggest that it may be possible to construct small-scale marine ecosystems using at least these three coral species. By focusing on their morphological changes, we can better understand their conditions and optimize their survival in extraterrestrial environments.