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Kodama K, Kuroki M, Yamakawa T, Shimizu M, Kintsu H, Horiguchi T. Remarkable shifts in the megabenthic community structure over four decades in Tokyo Bay, Japan, in relation to environmental variations. MARINE ENVIRONMENTAL RESEARCH 2024; 200:106640. [PMID: 39013226 DOI: 10.1016/j.marenvres.2024.106640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 06/25/2024] [Accepted: 07/05/2024] [Indexed: 07/18/2024]
Abstract
We investigated long-term changes in the megabenthic community in Tokyo Bay, Japan, using data from fisheries-independent trawl surveys conducted from 1977 to 2023. In addition, we examined the potential relationship between changes in biotic communities and environmental conditions. The total abundance and biomass exhibited an increasing trend until 1987, followed by a substantial decline from the late 1980s to the 1990s due to a decrease in small to medium-sized fish and crustacean species. Meanwhile, a marked increase in the number of large fish (including elasmobranchs), mollusks, and echinoids, was observed in the 2000s. These shifts in the megabenthic community structure were correlated with an increase in water temperature and a decrease in nutrient concentrations and copepod densities. Cumulative evidence suggests that a remarkable shift in the megabenthic community structure occurred between the 1970s and the 2020s, which was possibly associated with variations in the environmental conditions in Tokyo Bay.
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Affiliation(s)
- Keita Kodama
- Health and Environmental Risk Division, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki, 305-8506, Japan.
| | - Mari Kuroki
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657, Japan
| | - Takashi Yamakawa
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657, Japan
| | - Makoto Shimizu
- Faculty of Agriculture, The University of Tokyo, Bunkyo, Tokyo, 113-8657, Japan
| | - Hiroyuki Kintsu
- Health and Environmental Risk Division, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki, 305-8506, Japan
| | - Toshihiro Horiguchi
- Health and Environmental Risk Division, National Institute for Environmental Studies, Onogawa, Tsukuba, Ibaraki, 305-8506, Japan
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Yin Z, Zhang X, Wang S, Xu Y. Spatiotemporal variation of dissolved oxygen concentration in the northern Gulf of Mexico during the period of 1992-2017. MARINE POLLUTION BULLETIN 2024; 198:115771. [PMID: 37995592 DOI: 10.1016/j.marpolbul.2023.115771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 10/30/2023] [Accepted: 11/09/2023] [Indexed: 11/25/2023]
Abstract
Dissolved oxygen (DO) concentration is an important index of ocean systems. In this study, spatiotemporal variations in DO were analyzed in the northern Gulf of Mexico (NGM) for the period of 1992-2017. Temporal variation involves annual, monthly, and seasonal variations. The spatial scope ranged from the sea surface to 1000 m depth. The results show that: (1) DO decreased from 1992 to 2017 with a brief increase; (2) clear seasonal variation characteristics of DO were presented, and the seasonal average DO was relatively low in summer; (3) the monthly average trends of sea surface DO in different years were relatively consistent; and (4) with increasing water depth from seawater surface to 1000 m, the average DO of 1992 to 2017 tended to decrease and then increase. The results aim at shedding some light on the assessment of DO change in the NGM over the past quarter century.
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Affiliation(s)
- Zegao Yin
- Engineering College, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Ocean Engineering, Ocean University of China, Qingdao 266100, China
| | - Xuecong Zhang
- Engineering College, Ocean University of China, Qingdao 266100, China
| | - Sheng Wang
- Engineering College, Ocean University of China, Qingdao 266100, China
| | - Yu Xu
- Shandong Provincial Key Laboratory of Ocean Engineering, Ocean University of China, Qingdao 266100, China.
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Horiguchi T, Kodama K. What Caused Declines in Intertidal Invertebrate Populations around Fukushima Daiichi Nuclear Power Plant after the 2011 Great East Japan Earthquake, Tsunami, and Nuclear Disaster? TOXICS 2022; 10:toxics10050214. [PMID: 35622628 PMCID: PMC9147687 DOI: 10.3390/toxics10050214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/12/2022] [Accepted: 04/21/2022] [Indexed: 02/04/2023]
Abstract
We discuss possible causal factors for the decline in intertidal invertebrate populations around Fukushima Daiichi Nuclear Power Plant (FDNPP) after the 2011 Great East Japan Earthquake and subsequent tsunami and nuclear disaster on the basis of existing knowledge about the effects of radionuclides and ionizing radiation on aquatic organisms. We found a gap between effects observed in the laboratory and those observed in natural aquatic environments, and discuss possible reasons why. Considering the complexity of the environment, we conclude that it is critical to evaluate the effects of ionizing radiation combined with other biotic and abiotic environmental factors, together with the life-history traits of the species examined, for realistic assessment of population-level effects. Finally, we present possible causal factors for strange or abnormal phenomena observed in intertidal biota near FDNPP, namely declines in population densities and number of species of invertebrates, delayed recovery from these declines, and continuous sexual maturation in the rock shell population.
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Kodama K, Waku M, Sone R, Miyawaki D, Ishida T, Akatsuka T, Horiguchi T. Ontogenetic and temperature-dependent changes in tolerance to hypoxia and hydrogen sulfide during the early life stages of the Manila clam Ruditapes philippinarum. MARINE ENVIRONMENTAL RESEARCH 2018; 137:177-187. [PMID: 29325692 DOI: 10.1016/j.marenvres.2017.12.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/28/2017] [Accepted: 12/28/2017] [Indexed: 06/07/2023]
Abstract
Wind-induced upwelling of hypoxic waters containing hydrogen sulfide (H2S) sometimes causes mass mortalities of aquatic organisms inhabiting coastal areas, including the hypoxia-tolerant Manila clam Ruditapes philippinarum. We examined the tolerance of Manila clam to H2S under controlled laboratory conditions. Larvae and juveniles obtained by artificial fertilization or from a wild population were exposed to normoxic or to hypoxic water with or without un-ionized H2S (concentrations, 0.2-52.2 mg/L). Twenty-four-hour exposure experiments revealed ontogenetic changes in the clam's tolerance to H2S exposure: tolerance was enhanced from the larval stages to juveniles just after settlement but was attenuated as juveniles grew. Tolerance of larvae and juveniles to H2S exposure weakened as the water temperature rose from 20 to 28 °C. Prolonged 48-h exposure to H2S attenuated the tolerance of juveniles to H2S. Temporary suspension of H2S exposure by 24-h reoxygenation improved the ability of juveniles to withstand repeated H2S exposure.
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Affiliation(s)
- Keita Kodama
- Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan.
| | - Mitsuyasu Waku
- Fisheries Environment Research Department, Aichi Fisheries Research Institute, Gamagori, Aichi 443-0021, Japan
| | - Ryota Sone
- Fisheries Environment Research Department, Aichi Fisheries Research Institute, Gamagori, Aichi 443-0021, Japan
| | - Dai Miyawaki
- Fisheries Environment Research Department, Aichi Fisheries Research Institute, Gamagori, Aichi 443-0021, Japan
| | - Toshiro Ishida
- Fisheries Environment Research Department, Aichi Fisheries Research Institute, Gamagori, Aichi 443-0021, Japan
| | - Tetsuji Akatsuka
- Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
| | - Toshihiro Horiguchi
- Center for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan
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Nakano T, Yamada K, Okamura K. Duration rather than frequency of hypoxia causes mass mortality in ark shells (Anadara kagoshimensis). MARINE POLLUTION BULLETIN 2017; 125:86-91. [PMID: 28797544 DOI: 10.1016/j.marpolbul.2017.07.073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 06/07/2023]
Abstract
Hypoxia is associated with mass mortality in estuaries, but a direct causal relationship has not been proven to date. This study aimed to demonstrate this relationship and to evaluate how the duration of hypoxia affects the survival of ark shells (Anadara kagoshimensis) using mathematical modeling. The dissolved oxygen concentration was monitored at two stations in the innermost area of Ariake Bay, Japan, to calculate the duration of hypoxia. This was then included in a mathematical model to simulate the population density with sequential computation. The population density decreased with prolonged hypoxia, reaching a value close to the observed population density, indicating that hypoxia is the main cause of mass mortality in ark shells. Furthermore, the ark shell population disappeared in 8days with constant hypoxia but persisted when hypoxia was alternated with normoxia every 6 h. Therefore, mass mortality is caused by the duration rather than the frequency of hypoxia.
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Affiliation(s)
- Tadashi Nakano
- Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, 1551-8 Taira-machi, Nagasaki 851-2213, Japan.
| | - Katsumasa Yamada
- Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, 1551-8 Taira-machi, Nagasaki 851-2213, Japan
| | - Kazumaro Okamura
- Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, 1551-8 Taira-machi, Nagasaki 851-2213, Japan
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