A Study on Restoration of Eelgrass (Zostera marina) Damaged by Tsunami in Miyako Bay

Okada, Tomonari; Maruya, Yasuyuki; Nakayama, Keisuke; Iseri, Erina

doi:10.2208/kaigan.70.i_1186

Cited by 3 publications

(3 citation statements)

References 2 publications

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“…The outer bay area is usually occupied by temperate western North Pacific water, which brings enough nutrients in winter to support seaweed farms in the coastal area (Kakehi et al, 2018). Additional nutrients to the bay are provided by three rivers: Hei, Tsugaruishi,and Tashiro (25.8,5.16,and 3.78 m 3 s −1 , respectively, for annual average flow rate; Okada et al, 2014), although the quantity of nutrients input by the rivers are limited to low levels (57, 11, and 8 tN yr −1 for Hei, Tsugaruishi, and Tashiro rivers, respectively; Bernardo et al, 2023). With a population of 60 000 residents within the hinterland, Miyako Bay has maintained good water quality with 1-2 mg L −1 of chemical oxygen demand (MOE, 2022).…”

Section: Miyako Baymentioning

confidence: 99%

Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings

Ono,

Muraoka,

Hayashi

et al. 2024

Biogeosciences

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Abstract. The pH of coastal seawater varies based on several local forcings, such as water circulation, terrestrial inputs, and biological processes, and these forcings are changing along with global climate change. Understanding the mechanism of pH variation in each coastal area is thus important for a realistic future projection that considers changes in these forcings. From 2020 to 2021, we performed parallel year-round observations of pH and related ocean parameters at five stations around the Japanese coast (Miyako Bay, Shizugawa Bay, Kashiwazaki Coast, Hinase Archipelago, and Ohno Strait) to understand the characteristics of short-term pH variations and their forcings. Annual variability (∼ 1 standard deviation) of pH and aragonite saturation state (Ωar) were 0.05–0.09 and 0.25–0.29, respectively, for three areas with low anthropogenic pressures (Miyako Bay, Kashiwazaki Coast, and Shizugawa Bay), while it increased to 0.16–0.21 and 0.52–0.58, respectively, in two areas with medium anthropogenic pressures (Hinase Archipelago and Ohno Strait in Seto Inland Sea). Statistical assessment of temporal variability at various timescales revealed that most of the annual variabilities in both pH and Ωar were derived by short-term variation at a timescale of <10 d, rather than seasonal-scale variation. Our analyses further illustrated that most of the short-term pH variation was caused by biological processes, while both thermodynamic and biological processes equally contributed to the temporal variation in Ωar. The observed results showed that short-term acidification with Ωar < 1.5 occurred occasionally in Miyako and Shizugawa bays, while it occurred frequently in the Hinase Archipelago and Ohno Strait. Most of such short-term acidified events were related to short-term low-salinity events. Our analyses showed that the amplitude of short-term pH variation was linearly correlated with that of short-term salinity variation, and its regression coefficient at the time of high freshwater input was positively correlated with the nutrient concentration of the main river that flows into the coastal area.

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Section: Miyako Baymentioning

confidence: 99%

Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings

Ono,

Muraoka,

Hayashi

et al. 2024

Biogeosciences

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show abstract

Section: Miyako Baymentioning

confidence: 99%

Short-term variation of pH in seawaters around coastal areas of Japan: Characteristics and forcings

Ono

Muraoka²,

Hayashi

et al. 2023

Preprint

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Abstract. The pH of coastal seawater varies based on several local forcings, such as water circulation, terrestrial inputs, and biological processes, and these forcings can change along with global climate change. Understanding the mechanism of pH variation in each coastal area is thus important for a realistic future projection that considers changes in these forcings. From 2020 to 2021, we performed parallel year-round observations of pH and related ocean parameters at five stations around the Japanese coast (Miyako Bay, Shizugawa Bay, Kashiwazaki Coast, Hinase Archipelago, and Ohno Strait) to understand the characteristics of short-term pH variations and their forcings. Annual variability (~1 standard deviation) of pH and aragonite saturation state (Ωara) were 0.05–0.09 and 0.25–0.29, respectively, for three areas with low anthropogenic loadings (Miyako Bay, Kashiwazaki Coast, and Shizugawa Bay), while it increased to 0.16–0.21 and 0.52–0.58, respectively, in two areas with medium anthropogenic loadings (Hinase Archipelago and Ohno Strait in Seto Inland Sea). Statistical assessment of temporal variability at various timescales revealed that most of the annual variabilities in both pH and Ωara were derived by short-term variation at a timescale of < 10 days, rather than seasonal-scale variation. Our analyses further illustrated that most of the short-term pH variation was caused by biological processes, while both thermodynamic and biological processes equally contributed to the temporal variation in Ωara. The observed results showed that short-term acidification with Ωara < 1.5 occurred occasionally in Miyako and Shizugawa Bays, while it occurred frequently in the Hinase Archipelago and Ohno Strait. Most of such short-term acidified events were related to short-term low-salinity events. Our analyses showed that the amplitude of short-term pH variation was linearly correlated with that of short-term salinity variation, and its regression coefficient at the time of high freshwater input was positively correlated with the nutrient concentration of the main river that flows into the coastal area.

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“…The bay is well-known for its seaweed, scallop, oyster, abalone, and sea urchin fisheries (Miyako city website: https://www.city.miyako.iwate.jp/ suisan/ikuseikyougikai_gyogyoukeitai.html), which also attract tourists and enhance local tourism activities. It has been a known habitat of the eelgrass Zostera marina, and previous hydrodynamically oriented studies have focused on the damage and recovery of the population from the Great Tohoku Earthquake in March 2011 (e.g., Okada et al, 2014;Murakami et al, 2015). However, there is concern that rising sea temperatures along with the possible ocean acidification and deoxygenation may threaten such ecosystem services (Fujita, 2021;Ono et al, 2023).…”

Section: Study Site and Monitoring Setupmentioning

confidence: 99%

Development of a high-resolution marine ecosystem model for predicting the combined impacts of ocean acidification and deoxygenation

Bernardo,

Fujii,

Ono

2023

Front. Mar. Sci.

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An approach was developed to help evaluate and predict the combined effects of ocean acidification and deoxygenation on calcifying organisms along the coast of Japan. The Coastal and Regional Ocean COmmunity (CROCO) modeling system was set up to couple the Regional Ocean Modeling System (ROMS) to the Pelagic Interaction Scheme for Carbon and Ecosystem Studies (PISCES) biogeochemical model and used to reproduce physical and biochemical processes in the area around Miyako Bay, Iwate Prefecture, Japan. Future scenario cases were also set up, which used initial and boundary conditions based on Future Ocean Regional Projection (FORP) simulations. Present day simulations were able to reproduce the general features of observed physical and biochemical parameters, except for some rapid decreases in salinity, pH and aragonite saturation state (Ωarag). This suggests that more local factors which have not been introduced into the model, such as submarine groundwater discharge, may be involved, or that river inputs may be underestimated. Results of the future projections suggest a significant impact of global warming and ocean acidification on calcifying organisms for the worst case of climate change under the Representative Concentration Pathway (RCP) 8.5 scenario. In particular, it is feared that values of Ωarag would approach the critical level for calcifying organisms (Ωarag< 1.1) throughout the year, under which decreased larval shell lengths and malformation have been observed experimentally for the locally grown Haliotis discus hannai (Ezo Abalone) species. However, these findings may not be true for a different coastal locality, and this study highlights and continues to stress the importance of developing model setups capable of incorporating both regional and local factors affecting ocean acidification and deoxygenation.

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A Study on Restoration of Eelgrass (Zostera marina) Damaged by Tsunami in Miyako Bay

Cited by 3 publications

References 2 publications

Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings

Short-term variation in pH in seawaters around coastal areas of Japan: characteristics and forcings

Short-term variation of pH in seawaters around coastal areas of Japan: Characteristics and forcings

Development of a high-resolution marine ecosystem model for predicting the combined impacts of ocean acidification and deoxygenation

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