Long‐term changes in the assemblage of demersal fishes and invertebrates in relation to environmental variations in Tokyo Bay, Japan

Kodama, Keita; Aoki, Ichiro; Shimizu, Makoto; Taniuchi, Toru

doi:10.1046/j.1365-2400.2002.00313.x

Cited by 38 publications

(37 citation statements)

References 15 publications

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“…These result in reduced fisheries, including valuable finfishes and crustaceans (Jørgensen, 1980;Nissling and Vallin, 1996;Rabalais and Turner, 2001;Cheng et al, 2002;Eby and Crowder, 2002;Kodama et al, 2002;Wu, 2002;Wu et al, 2003;Baird et al, 2004;Breitburg et al, 2009). Increasing nutrient loads that also change the nutrient ratios can affect the composition of the phytoplankton community and can shift trophic interactions.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and distribution of natural and human-caused hypoxia

et al. 2010

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Abstract. Water masses can become undersaturated with oxygen when natural processes alone or in combination with anthropogenic processes produce enough organic carbon that is aerobically decomposed faster than the rate of oxygen reaeration. The dominant natural processes usually involved are photosynthetic carbon production and microbial respiration. The re-supply rate is indirectly related to its isolation from the surface layer. Hypoxic water masses (<2 mg L −1 , or approximately 30% saturation) can form, therefore, under "natural" conditions, and are more likely to occur in marine systems when the water residence time is extended, water exchange and ventilation are minimal, stratification occurs, and where carbon production and export to the bottom layer are relatively high. Hypoxia has occurred through geological time and naturally occurs in oxygen minimum zones, deep basins, eastern boundary upwelling systems, and fjords.Hypoxia development and continuation in many areas of the world's coastal ocean is accelerated by human activities, especially where nutrient loading increased in the Anthropocene. This higher loading set in motion a cascading set of events related to eutrophication. The formation of hypoxic areas has been exacerbated by any combination of interactions that increase primary production and accumulation of organic carbon leading to increased respiratory demand for oxygen below a seasonal or permanent pycnocline. Nutrient loading is likely to increase further as population growth and resource intensification rises, especially with increased Correspondence to: N. N. Rabalais (nrabalais@lumcon.edu) dependency on crops using fertilizers, burning of fossil fuels, urbanization, and waste water generation. It is likely that the occurrence and persistence of hypoxia will be even more widespread and have more impacts than presently observed.Global climate change will further complicate the causative factors in both natural and human-caused hypoxia. The likelihood of strengthened stratification alone, from increased surface water temperature as the global climate warms, is sufficient to worsen hypoxia where it currently exists and facilitate its formation in additional waters. Increased precipitation that increases freshwater discharge and flux of nutrients will result in increased primary production in the receiving waters up to a point. The interplay of increased nutrients and stratification where they occur will aggravate and accelerate hypoxia. Changes in wind fields may expand oxygen minimum zones onto more continental shelf areas. On the other hand, not all regions will experience increased precipitation, some oceanic water temperatures may decrease as currents shift, and frequency and severity of tropical storms may increase and temporarily disrupt hypoxia more often.The consequences of global warming and climate change are effectively uncontrollable at least in the near term. On the other hand, the consequences of eutrophication-induced hypoxia can be reversed if long-term, broad-scale, and per...

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Section: Introductionmentioning

confidence: 99%

Dynamics and distribution of natural and human-caused hypoxia

et al. 2010

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“…In Tokyo Bay, Japan, P. yokohamae is the dominant species in the megabenthic assemblage and is a highly valued fish species exploited by commercial fishers in the bay [2,3]. However, despite the importance of P.…”

Section: Introductionmentioning

confidence: 99%

“…1). Detailed methods of the bottom trawl surveys have been described by Kodama et al [2]. The specimens were brought back to the laboratory without any fixation.…”

Section: Introductionmentioning

confidence: 99%

Comparison between surface-reading and cross-section methods using sagittal otolith for age determination of the marbled sole Pseudopleuronectes yokohamae

et al. 2009

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Title:Comparison between surface-reading and cross-section methods using sagittal otolith for age determination of the marbled sole Pseudopleuronectes yokohamae Authors:Jeong-Hoon LEE ABSTRACTTo find an appropriate method for age determination in the marbled solePseudopleuronectes yokohamae in Tokyo Bay, Japan, sagittal otoliths of 1343 individuals were observed by surface-reading and cross-section methods and the results were compared. Opaque zones occurred once a year and were regarded as annuli in both methods. The surface-reading method sometimes provided a lower count of the number of annuli than the cross-section method, and the frequency of this discrepancy was highest in older fish (males above 5 years, females above 4 years). The oldest female fish was estimated to be age 10 years by the cross-section method but 8 years by the surface-reading method. The cross-section method could provide a more accurate estimate of age and is therefore likely to be indispensable to estimations of longevity. In contrast, the surface-reading method is superior in terms of cost and time efficiency but is likely to underestimate the ages of older fish. However, growth equations based on age estimated by the surface-reading method were sufficiently accurate if males ≥ 5 years and females ≥ 4 years were combined as specific, single age groups of 5+ and 4+, respectively. KEY WORDSAge determination, Cross-section method, Growth, Otolith, Pseudopleuronectes yokohamae, Surface-reading method, Tokyo Bay 3 INTRODUCTIONThe marbled sole Pseudopleuronectes yokohamae distributed in Japan from southernHokkaido to Oita Prefecture in Kyushu, as well as in the Yellow Sea, the Bohai Sea, and the northern part of the East China Sea [1]. In Tokyo Bay, Japan, P. yokohamae is the dominant species in the megabenthic assemblage and is a highly valued fish species exploited by commercial fishers in the bay [2,3]. However, despite the importance of P.yokohamae as a commercial resource, the abundance of this species has markedly decreased since the late 1980s. According to statistics from the Shiba Branch of Yokohama City Fisheries Cooperative Association, the annual catch of P. yokohamae in Tokyo Bay exceeded approximately 500 t in the mid 1980s, but by the 2000s it had decreased substantially to around 50 t. Therefore, there is a need for elucidation of the cause of the decline of P. yokohamae for the recovery of the stock in the bay.To understand mechanisms of the population dynamics of P. yokohamae in Tokyo Bay, we have to clarify the critical life-history stage (or stages) that determine the year-class strength, and identify factors that affect mortality during the critical life-history stage, as well as consideration of changes in life history traits (e.g., reproduction), which may contribute to the population decline. In studying these matters, age and growth is one of important life history traits [4,5].For the estimation of age and growth, establishment of an accurate aging procedure is indispensable. Age and growth of P. yokohamae have p...

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“…2). Detailed methods for the bottom trawl surveys have been previously described [2]. All specimens were brought back to the laboratory without fixation.…”

Section: Investigations Into the Fundamental Life History Traits Of Mmentioning

confidence: 99%

“…This species showed high dominance in the demersal assemblage in Tokyo Bay during the mid-1980s, according to a long-term bottom trawl survey [2]. Abundance of marbled sole in Tokyo Bay, however, has decreased markedly since the late 1980s.…”

Section: Introductionmentioning

confidence: 97%

Changes in growth of marbled sole Pseudopleuronectes yokohamae between high and low stock-size periods in Tokyo Bay, Japan

et al. 2009

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We examined age and growth of the marbled sole Pseudopleuronectes yokohamae collected from Tokyo Bay, Japan, during 2002−2008 when the stock size remained low. The von Bertalanffy growth equations differed significantly between sexes, and females attained a larger standard length than males of the same age. We compared the results with those reported for 1974−1983 and 1986−1988, when the stock size was high. The growth of marbled sole in Tokyo Bay during the 2000s was significantly higher than the growth in the 1970s and 1980s for both sexes. To explore possible factors causing changes in the growth, we examined bottom water temperature and population density. We found that the population density decreased and the bottom water temperature increased between the late 1970s and the 2000s. However, despite evidence of changes in population densities and water temperatures, further study is needed to determine the main factors causing the observed changes in growth.

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Long‐term changes in the assemblage of demersal fishes and invertebrates in relation to environmental variations in Tokyo Bay, Japan

Cited by 38 publications

References 15 publications

Dynamics and distribution of natural and human-caused hypoxia

Dynamics and distribution of natural and human-caused hypoxia

Comparison between surface-reading and cross-section methods using sagittal otolith for age determination of the marbled sole Pseudopleuronectes yokohamae

Changes in growth of marbled sole Pseudopleuronectes yokohamae between high and low stock-size periods in Tokyo Bay, Japan

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