The Nutrient and Carbon Dynamics that Mutually Benefit Coral and Seagrass in Mixed Habitats under the Influence of Groundwater at Bise Coral Reef, Okinawa, Japan

Tomihiko Higuchi<sup>1,4</sup>; Kimberly K. Takagi<sup>2,5</sup>; Kana Matoba<sup>2</sup>; Syusei Kobayashi<sup>1</sup>; Ryota Tsurumi<sup>1</sup>; Seiji Arakaki<sup>2,6</sup>; Yoshikatsu Nakano<sup>3</sup>; Hiroyuki Fujimura<sup>1</sup>; Tamotsu Oomori<sup>1</sup>; Makoto Tsuchiya<sup>1</sup>

The Nutrient and Carbon Dynamics that Mutually Benefit Coral and Seagrass in Mixed Habitats under the Influence of Groundwater at Bise Coral Reef, Okinawa, Japan

Tomihiko Higuchi^1,4

, Kimberly K. Takagi^2,5

, Kana Matoba²

, Syusei Kobayashi¹

, Ryota Tsurumi¹

, Seiji Arakaki^2,6

, Yoshikatsu Nakano³

, Hiroyuki Fujimura¹

, Tamotsu Oomori¹

, Makoto Tsuchiya¹

1. Department of Chemistry, Biology and Marine Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
2. Graduate School of Engineering and Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan
3. Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, 3422 Sesoko, Motobu, Okinawa 905-0227, Japan
4. Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Surugaku, Shizuoka, 422-8529, Japan
5. Department of Marine Science, University of Georgia, 325 Sanford Drive, Athens, Georgia, 30602, USA
6. Amakusa Marine Biological Laboratory, Kyushu University, 2231 Tomioka, Reihoku, Amakusa, Kumamoto 863-2507, Japan

Author

Correspondence author
International Journal of Marine Science, 2014, Vol. 4, No. 1 doi: 10.5376/ijms.2014.04.0001
Received: 27 Oct., 2013 Accepted: 29 Nov., 2013 Published: 04 Jan., 2014

This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Preferred citation for this article:

Higuchi et al, 2014, The Nutrient and Carbon Dynamics that Mutually Benefit Coral and Seagrass in Mixed Habitats under the Influence of Groundwater at Bise Coral Reef, Okinawa, Japan, International Journal of Marine Science, Vol.4, No.1 1-15 (doi: 10.5376/ijms.2014.04.0001)

Abstract

The coral species, Montipora digitata and seagrass, Thalassia hemprichii, co-inhabit the southern portion of the reef moat in Bise, Okinawa, Japan. To elucidate the biogeochemical relationship between coral and seagrass in mixed communities of the coral reef ecosystem, the carbon metabolisms and the inorganic nitrogen flux rates were estimated in various reef habitats. We used benthic chambers to investigate sandy, seagrass, coral-seagrass mixed communities, coral, and acorn worm habitats. Relatively high concentrations of nitrate and nitrite ions (NO_x) were observed in all habitats due to coastal groundwater inflow. The uptake rate constant of NO_x was the highest in the coral-seagrass habitat and was significantly different from the rate constant in the seagrass habitat, indicating that seagrass benefits from co-inhabitation with coral. Dissolution of CaCO₃ was observed in the seagrass and coral-seagrass communities. This decline in basal coral carbonate substrate may contribute to increased fragmentation and dispersal of the coral habitat. On a biogeochemical scale, the coral-seagrass relationship benefits the seagrass in terms of NO_x availability and benefits the coral in terms of carbonate dissolution, increasing fragmentation, and furthering habitat development.

Keywords

Carbon metabolism; Inorganic nitrogen flux; Coral-seagrass mixed community; Coral reef; Benthic chamber

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International Journal of Marine Science

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