Hemocyte Responses of the Oyster Crassostrea hongkongensis Exposed to Diel-Cycling Hypoxia and Salinity Change

Marine hypoxia caused by nutrient enrichment in coastal waters has become a global problem for decades, especially diel-cycling hypoxia that occurs frequently in the summer season. On the contrary, sudden rainstorms, and freshwater discharge make salinity in estuarine and coastal ecosystems variable, which often occurs with hypoxia. We found mass mortality of the Hong Kong oyster Crassostrea hongkongensis in the field where hypoxia and salinity fluctuation co-occur in the summer season during the past several years. To investigate the effects of diel-cycling hypoxia and salinity changes on the hemocyte immune function of C. hongkongensis, oysters were exposed to a combined effect of two dissolved oxygen (DO) concentrations (24 h normal oxygen 6 mg/L, 12 h normal oxygen 6 mg/L, and 12 h hypoxia 2 mg/L) and three salinities (10, 25, and 35‰) for 14 days. Subsequently, all treatments were restored to constant normal oxygen (6 mg/L) and salinity under 25‰ for 3 days to study the recovery of hemocyte immune function from the combined stress. Hemocyte parameters were analyzed by flow cytometry, including hemocyte mortality (HM), total hemocyte count (THC), phagocytosis (PHA), esterase (EST) activity, reactive oxygen species (ROS), lysosomal content (LYSO), and mitochondrial number (MN). The experimental results showed that diel-cycling hypoxia and salinity changes have obvious interactive effects on various immune parameters. In detail, diel-cycling hypoxia and decreases in salinity led to increased HM, and low salinity caused heavier impacts. In addition, low salinity, and diel-cycling hypoxia also led to decreases in LYSO, EST, and THC, while the decrease of PHA only occurs in the early stage. On the contrary, ROS production increased significantly under low salinity and hypoxic conditions. After 3-day recovery, THC, PHA, EST, LYSO, and MN were basically restored to normal, while HM and ROS were still significantly affected by diel-cycling hypoxia and salinity change, indicating that the combined stress of diel-cycling hypoxia and salinity changes had latent effects on the immune function of C. hongkongensis. Our results highlight that diel-cycling hypoxia and salinity change may impair the health and survival of the Hong Kong oyster C. hongkongensis and may be the key factors for the mass mortality of this oyster in the field.

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The Effects of Temperature and Salinity Stressors on the Survival, Condition, and Valve Closure of the Manila Clam, Venerupis philippinarum in a Holding Facility

10.20944/preprints202106.0345.v1 ◽

2021 ◽

Author(s):

Hyeonmi Bae ◽

Jibin Im ◽

Soobin Joo ◽

Boongho Cho ◽

Taewon Kim

Keyword(s):

Manila Clam ◽

Effect Of Temperature ◽

Valve Closure ◽

Salinity Fluctuation ◽

Venerupis Philippinarum ◽

Low Salinity ◽

Salinity Changes ◽

Different Temperatures ◽

Effects Of Temperature ◽

Survival Condition

We investigated the response of the Manila clam Venerupis philippinarum to possible temperature and salinity changes in a holding facility. First, clams were exposed to four temperatures for 15 days. Valve closure and survival of clams exposed to seawater at 18℃ were higher than that of those exposed to seawater at 24℃. Second, clams were exposed to six salinities for 15 days. Survival of clams exposed to two salinity fluctuation conditions (24–30 and 27–24 psu) was lower than that of clams exposed to constant 30 psu conditions. Valve closures of clams exposed to constant low salinity conditions (24 psu) and two salinity fluctuation conditions (24–30 and 27–24 psu) were higher than of those exposed to constant 30 psu conditions. Lastly, clams were exposed to two different temperatures and three different salinities conditions for 8 days. Valve closure and survival decreased significantly under the combination of 24℃ and 18 psu. These results suggest that an increase in temperature or a wider range of salinity fluctuations are detrimental to the survival of the Manila clam. The synergistic effect of temperature and salinity stressors may decrease the survival period of clams compared to the effect of a single stressor.

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The Effects of Temperature and Salinity Stressors on the Survival, Condition and Valve Closure of the Manila Clam, Venerupis philippinarum in a Holding Facility

Journal of Marine Science and Engineering ◽

10.3390/jmse9070754 ◽

2021 ◽

Vol 9 (7) ◽

pp. 754

Author(s):

Hyeonmi Bae ◽

Jibin Im ◽

Soobin Joo ◽

Boongho Cho ◽

Taewon Kim

Keyword(s):

Manila Clam ◽

Effect Of Temperature ◽

Valve Closure ◽

Salinity Fluctuation ◽

Venerupis Philippinarum ◽

Low Salinity ◽

Salinity Changes ◽

Different Temperatures ◽

Effects Of Temperature ◽

Survival Condition

This article investigates the response of the Manila clam Venerupis philippinarum to possible temperature and salinity changes in a holding facility. First, clams are exposed to four temperatures for 15 days. Valve closure and survival of clams exposed to seawater at 18 °C are higher than those exposed to seawater at 24 °C. Second, clams are exposed to six salinities for 15 days. Survival of clams exposed to two salinity fluctuation conditions (24–30 and 27–24 psu) is lower than that of clams exposed to constant 30 psu conditions. Valve closures of clams exposed to constant low salinity conditions (24 psu) and two salinity fluctuation conditions (24–30 and 27–24 psu) are higher than those exposed to constant 30 psu conditions. Lastly, clams are exposed to two different temperatures and three different salinities conditions for eight days. Valve closure and survival decreased significantly under the combination of 24 °C and 18 psu. These results suggest that an increase in temperature or a wider range of salinity fluctuations are detrimental to the survival of the Manila clam. The synergistic effect of temperature and salinity stressors may decrease the survival period of clams compared to the effect of a single stressor.

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Mass Mortality of Estuarine Fauna at Bideford, P.E.I., Associated with Abnormally Low Salinities

Journal of the Fisheries Research Board of Canada ◽

10.1139/f69-064 ◽

1969 ◽

Vol 26 (3) ◽

pp. 701-704 ◽

Cited By ~ 10

Author(s):

M. L. H. Thomas ◽

G. N. White

Keyword(s):

Shallow Water ◽

Fresh Water ◽

Mass Mortality ◽

Salinity Change ◽

Low Salinity

Spring thaw discharges large quantities of fresh water into estuaries in the Gulf of St. Lawrence. Surface freshwater layers of 1 m are normal but deeper water usually remains at close to full salinity. Shallow-water animals are adapted to withstand low salinities but those from deeper water are not. In May 1967 an up-estuary gale caused the buildup of an extraordinarily deep freshwater layer in Bideford River, P.E.I.; salinities at 3 m fell to less than 1‰. Scuba surveys after this phenomenon revealed extensive mortalities in a variety of species. Several of these species often occur in low-salinity areas and it is suggested that mortalities resulted from the very rapid salinity change combined with warming water temperatures.

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Comparison of the Biochemical Composition and Nutritional Quality Between Diploid and Triploid Hong Kong Oysters, Crassostrea hongkongensis

Frontiers in Physiology ◽

10.3389/fphys.2018.01674 ◽

2018 ◽

Vol 9 ◽

Cited By ~ 8

Author(s):

Yanping Qin ◽

Yuehuan Zhang ◽

Haitao Ma ◽

Xiangwei Wu ◽

Shu Xiao ◽

...

Keyword(s):

Hong Kong ◽

Biochemical Composition ◽

Nutritional Quality ◽

Crassostrea Hongkongensis

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A thymosin beta-4 is involved in production of hemocytes and immune defense of Hong Kong oyster, Crassostrea hongkongensis

Developmental & Comparative Immunology ◽

10.1016/j.dci.2015.12.007 ◽

2016 ◽

Vol 57 ◽

pp. 1-9 ◽

Cited By ~ 14

Author(s):

Jun Li ◽

Yuehuan Zhang ◽

Ying Liu ◽

Yang Zhang ◽

Zhiming Xiang ◽

...

Keyword(s):

Hong Kong ◽

Immune Defense ◽

Crassostrea Hongkongensis ◽

Thymosin Beta 4

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Holocene lake salinity changes in the Wimmera, southeastern Australia, provide evidence for millennial-scale climate variability

Quaternary Research ◽

10.1016/j.yqres.2011.09.013 ◽

2012 ◽

Vol 77 (1) ◽

pp. 65-76 ◽

Cited By ~ 24

Author(s):

Justine Kemp ◽

Lynda C. Radke ◽

Jon Olley ◽

Steve Juggins ◽

Patrick De Deckker

Keyword(s):

Brine Shrimp ◽

Optically Stimulated Luminescence ◽

Weighted Averaging ◽

Faecal Pellets ◽

Low Salinity ◽

Salinity Changes ◽

Southeastern Australia ◽

Wind Circulation ◽

Murray Basin ◽

Lake Salinity

Palaeosalinity records for groundwater-influenced lakes in the southwest Murray Basin were constructed from an ostracod-based, weighted-averaging transfer function, supplemented with evidence from Campylodiscus clypeus (diatom), charophyte oogonia, Coxiella striata (gastropod), Elphidium sp. (foraminifera), Daphniopsis sp. ephippia (Cladocera), and brine shrimp (Parartemia zietziana) faecal pellets, the δ18O of ostracods, and > 130 μm quartz sand counts. The chronology is based on optically stimulated luminescence and calibrated radiocarbon ages. Relatively wet conditions are marked by lower salinities between 9600 yr and 5700 yr ago, but mutually exclusive high- and low-salinity ostracod communities suggest substantial variability in effective precipitation in the early Holocene. A drier climate was firmly in place by 4500 yr and is marked at the groundwater-dominated NW Jacka Lake by an increase in aeolian quartz and at Jacka Lake, by a switch from surface-water to groundwater dominance. Short-lived, low-salinity events at 8800, 7200, 5900, 4800, 2400, 1300 and 400 yr are similar in timing and number to those recorded on Australia's southern continental shelf, and globally, and provide evidence for the existence of the ~ 1500-yr cycle in mainland southern Australia. We surmise that these are cool events associated with periodic equatorward shifts in the westerly wind circulation.

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