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

1969 ◽  
Vol 26 (3) ◽  
pp. 701-704 ◽  
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.

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

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhe Xie ◽  
Shuaishuai Wei ◽  
Haomiao Dong ◽  
Hui Chen ◽  
Qianqian Zhang ◽  
...  
Keyword(s):  
Hong Kong ◽  
Immune Function ◽  
Summer Season ◽  
Mass Mortality ◽  
Combined Stress ◽  
Salinity Change ◽  
Salinity Fluctuation ◽  
Crassostrea Hongkongensis ◽  
Low Salinity ◽  
Salinity Changes

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.

SALT ACCUMULATION IN A GLACIAL TILL SOIL IN THE PRESENCE OF SALINE GROUNDWATER AT SHALLOW DEPTHS

1963 ◽  
Vol 43 (1) ◽  
pp. 135-140 ◽  
Author(s):  
J. C. van Schaik ◽  
R. A. Milne
Keyword(s):  
Shallow Water ◽  
Glacial Till ◽  
Salt Accumulation ◽  
Saline Groundwater ◽  
Low Salinity ◽  
Saturation Extract ◽  
Tile Drains ◽  
Southern Alberta ◽  
Water Tables ◽  
Fallow Soil

Considerable salt accumulation occurred in a grass-covered soil in southern Alberta where the saline groundwater was maintained at a depth of 3 feet. The SAR values of the saturation extract increased significantly under grass, and indications are that this increase was mainly due to precipitation of calcium. A fallow soil did not show a significant salt accumulation above the water table.It is suggested that a leaching program is necessary to maintain low salinity where shallow water tables are present and shallow tile drains are used.

Aborigines - Was It Smallpox?

1987 ◽  
Vol 15 (5) ◽  
pp. 45-48
Author(s):  
B. Wright
Keyword(s):  
Shallow Water ◽  
Fresh Water ◽  
Male And Female ◽  
Aboriginal Australia ◽  
Sydney Harbour ◽  
Female Convicts ◽  
Port Jackson ◽  
Open Nature

When the fleet of British warships and transports led by H.M.S. Supply entered Botany Bay on the 18th of January 1788, the white invasion of Aboriginal Australia had begun. Captain Arthur Phillip in Supply was followed over the next two days by H.M.S. Sirius, six transports and three store ships. On the 26th January the Frenchman, La Perouse, with the ships La Boussole and L’Astrolabe, arrived at Botany Bay and remained there until the 10th of March, 1788. Because of the open nature of the bay, its shallow water and the lack of plentiful fresh water, Phillip decided to move the settlement, and on the 25th January sailed to Port Jackson (Sydney Harbour) in Supply, with the transports following on the 26th of January. The white invasion and occupancy of Australia started in reality when the whole of Phillip’s fleet and colonists were anchored at the east of Sydney Cove. On board Phillip’s eleven ships came 736 male and female convicts, 17 convict children, 211 marines accompanied by their wives and children.

Sustaining olfaction at low salinities: mapping ion flux associated with the olfactory sensilla of the blue crab Callinectes sapidus

2000 ◽  
Vol 203 (20) ◽  
pp. 3145-3152 ◽  
Author(s):  
R.A. Gleeson ◽  
K. Hammar ◽  
P.J. Smith
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
Callinectes Sapidus ◽  
External Environment ◽  
Structural Data ◽  
Olfactory Sensilla ◽  
Low Salinity ◽  
Ion Movement ◽  
Ion Efflux ◽  
Net Flux

To test the hypothesis of a diffusion-generated, ionic/osmotic microenvironment within the olfactory sensilla (aesthetascs), flux gradients of Ca(2+) and K(+) associated with the external surfaces of these sensilla were spatially mapped using self-referencing, ion-selective microelectrodes. Blue crabs (Callinectes sapidus) acclimated to low-salinity conditions (15% sea water and fresh water) showed a net efflux of ions from the aesthetascs. The region of maximum flux associated with each aesthetasc conformed to that predicted from structural data and corresponded to the permeable region of the cuticle separating the olfactory dendrites from the external environment. Estimates of net flux from the entire tuft of aesthetascs for both Ca(2+) and K(+) fell within the predicted range on the basis of comparisons with (22)Na(+) flux measured previously and assuming a passive diffusion model of ion movement from the hemolymph to the sensillar lymph and, ultimately, to the external environment. The maximum concentrations of these ions measured deep within the tuft are discussed in the light of a potential across the aesthetascs that may limit ion efflux at low salinities.

Acropora abundance and size in the Maldives six years after the 1998 mass mortality: patterns across reef typologies and depths

2010 ◽  
Vol 90 (5) ◽  
pp. 919-922 ◽  
Author(s):  
Roberta Lasagna ◽  
Giancarlo Albertelli ◽  
Carla Morri ◽  
Carlo Nike Bianchi
Keyword(s):  
Coral Reefs ◽  
Spatial Variability ◽  
Shallow Water ◽  
Growth Rates ◽  
Mass Mortality ◽  
Sea Surface ◽  
Extension Rate ◽  
Reef Corals ◽  
Mass Mortality Event ◽  
Mean Size

In 1998, in coincidence with high sea surface temperatures, Maldivian reef corals were severely affected by mass mortality following bleaching. Tabular Acropora corals, formerly abundant in shallow water, were nearly exterminated. Recovery started soon, and in 2004 Maldivian reefs appeared rich in tabular Acropora colonies again, especially at some sites. This study aimed at determining the degree of spatial variability of tabular Acropora abundance and size among reef typologies (ocean versus lagoon reefs) and depth zones (4–6, 10–12 and 16–18 m) 6 years after the mass mortality event. A total of 192 tabular Acropora colonies (Ø > 16 cm) were counted and measured in six sites. Their abundance differed between reef typologies and according to depth zones, with the highest values in deep lagoon reefs. Colony mean size differed only among depth zones, the largest colonies (up to 105 cm) being found in shallow reefs. Assuming a radial extension rate of 10 cm · yr−1, colonies larger than 65 cm can be interpreted as the survivors of the mass mortality of 1998; conversely, they may represent the result of enhanced growth rates in uncrowded situations as those characterizing the coral reefs of the Maldives in 2004.

scholarly journals High Nitrate and Phosphate Ions Reduction in Modified Low Salinity Fresh Water through Microalgae Cultivation

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 129 ◽  
Author(s):  
Ahmad Mustaffa ◽  
Ku Ku Hamid ◽  
Mohibah Musa ◽  
Juferi Idris ◽  
Roslina Ramli
Keyword(s):  
Fresh Water ◽  
Biological Treatment ◽  
Carbonic Acid ◽  
Ambient Air ◽  
Biofuel Production ◽  
Water Medium ◽  
Organic Fertiliser ◽  
Nitrate Ions ◽  
Low Salinity ◽  
Phosphate Ions

The treatment of nitrate and phosphate ions in fresh water such as streams, rivers, lakes, reservoirs, and wetlands through biological treatment has been getting more crucial and popular in recent years. This paper reports the reduction of nitrate and phosphate ions in modified low salinity fresh water via the cultivation of a microalgae strain, e.g., Tetraspora sp. and Spirogyra sp. The low salinity fresh water (9054 to 9992 ppm) was modified with the addition of organic fertiliser (VermiCompost Tea) and used as the cultivation medium to grow microalgae. The microalgae strains were grown under controlled conditions in an indoor laboratory for 14 days. The initial concentrations of nitrate and phosphate ions in the modified fresh water sample were 1.17 mg/L and 0.10 mg/L, respectively. The reduction of nitrate and phosphate ions associated with the effect of cultivation of Tetraspora sp. and Spirogyra sp. in ambient air (0.03% of CO2) and 15% of CO2 was investigated. In ambient air, the cultivation of Tetraspora sp. and Spirogyra sp. greatly reduced the nitrate ions concentration from 5.96 ± 0.28 to 0.37 ± 0.05 mg/L and from 2.35 ± 0.19 to 0.59 ± 0.08 mg/L, respectively. A 100% reduction of phosphate ions was observed in the cultivation of Tetraspora sp. and Spirogyra sp. from 0.52 ± 0.10 mg/L in 13 days of and from 0.63 ± 0.15 mg/L in 6 days, respectively. Meanwhile, with the aeration of 15% of CO2, after the 14 days cultivation of Tetraspora sp. and Spirogyra sp. reduced the nitrate ions concentration from 5.27 ± 0.06 to 1.80 ± 0.20 mg/L and from 4.73 ± 0.12 to 2.80 ± 0.10 mg/L, respectively. The excessive CO2 in water consequently lowered the pH of water medium from 7.18 to 6.60 due to the formation of carbonic acid (H2CO3). It was feasible to couple the removal of nitrogen and phosphorus in Sungai Sura (4°42″28.2° N 103°26″12.1° E) while cultivating microalgae through biological treatment to produce biomass for biofuel production.

Distribution and rhythmic locomotor patterns of estuarine and open-shore populations of Carcinus maenas

1992 ◽  
Vol 72 (3) ◽  
pp. 599-609 ◽  
Author(s):  
I. J. McGaw ◽  
E. Naylor
Keyword(s):  
Locomotor Activity ◽  
Salinity Tolerance ◽  
Prolonged Exposure ◽  
Carcinus Maenas ◽  
Salinity Change ◽  
Low Salinity ◽  
Salinity Reduction ◽  
Locomotor Patterns

Populations of Carcinus maenas (Crustacea: Decapoda) from an estuary and from the open shore were compared for salinity tolerance and rhythmic locomotor activity. Estuarine crabs were shown to be predominantly green; red and orange individuals were rare within the estuary in contrast to the open shore. Red crabs were less able to tolerate prolonged exposure to low salinity than green crabs. Spontaneous circatidal rhythms of locomotor activity were similar in red and green forms, but red crabs from the open shore reacted earlier, and were more active upon salinity reduction, than green crabs from the estuary which also showed rapid habituation to episodes of salinity change.

scholarly journals Marsh Madness: Restoring Tidal Wetlands in Our Estuaries

2021 ◽  
Vol 9 ◽  
Author(s):  
Stacy Sherman ◽  
Rosemary Hartman
Keyword(s):  
Natural Disasters ◽  
Shallow Water ◽  
Sea Level Rise ◽  
Sea Level ◽  
Fresh Water ◽  
San Francisco ◽  
San Francisco Estuary ◽  
Tidal Wetlands ◽  
Safe Place

Just like people, fish need a safe place to find food and grow up. For fish that travel between fresh water and the ocean, tidal wetlands are a perfect neighborhood, with lots of habitat and food. Tidal wetlands are areas of shallow water where tides from the ocean cover the land with water every day. Besides providing a home for fish and water-loving plants, tidal wetlands also help protect people and their property from natural disasters like storms, and from sea-level rise. People have not always understood the value of wetlands, so billions of acres of them have been filled to farm or build on. In the San Francisco Estuary, more than 90% of wetlands were converted to other uses in <150 years! People now understand why wetlands are important, so protecting and restoring wetlands is a top priority.

scholarly journals Salinity change and cell volume: the response of tissues from the estuarine mussel Geukensia demissa.

1996 ◽  
Vol 199 (7) ◽  
pp. 1619-1630
Author(s):  
D S Neufeld ◽  
S H Wright
Keyword(s):  
Cell Volume ◽  
Geukensia Demissa ◽  
Cell Water ◽  
Salinity Change ◽  
Short Term ◽  
Solute Content ◽  
Low Salinity ◽  
Cell Height ◽  
Water Space ◽  
Lateral Cell

The response of cell volume to changes in external salinity was assessed in four tissues (gill, mantle, hemolymph cells and ventricle) of the estuarine mussel Geukensia demissa by using one or more of the following three indicators of cell volume response: changes in cell dimensions, cell water space and cell solute content. All three techniques indicated that short-term volume regulation was generally absent from gill tissue. Lateral cell height in gills, measured using differential interference contrast (DIC) microscopy, increased by approximately 20% after an abrupt exposure to reduced salinity (60% artificial sea water, ASW). There was significant variability in the observance of a regulatory volume decrease (RVD) subsequent to the initial swelling; cells remained swollen for 1 h after low-salinity exposure in two-thirds of the trials, while there was a return of cell volume towards control values in the remaining one-third of the trials. Lateral cell height increased linearly when salinity was gradually decreased from 100 to 60% ASW over 135 min. Cell height then returned to control values when the salinity was abruptly returned to 100% ASW, indicating that an RVD was not elicited by a slow change in salinity of the type normally encountered by estuarine mussels. Cumulative cell water space in gills increased by 47% after exposure to 60% ASW and the cells remained swollen for at least 4 h, returning to control values when gills were returned to 100% ASW. Consistent with the overall lack of an RVD, there was only a small decrease (approximately 5%) in cumulative osmolyte content (primarily taurine, betaine and K+) after 4 h in 60% ASW. Decreases in both cell water space and osmolyte content after 3 weeks of acclimation to 60% ASW indicated a long-term RVD of approximately 60%. Individual cells in the mantle epithelium also generally lacked an RVD in response to lowered salinity. Both abrupt and gradual decreases in salinity caused an increase in mantle cell height to a maximum of 25-30%, and cell height returned to the control height when salinity was abruptly returned to 100% ASW. Corresponding with the lack of an RVD in individual mantle cells, there was no change in solute content of the mantle tissue after 4 h of exposure to low salinity. The response of the volume of spherical hemolymph cells to 1 h of abrupt exposure to low salinity, calculated from measured cell diameters, likewise indicated that an RVD is generally lacking in these hemolymph cells. In the ventricle, however, there was a significant decrease in amino acid and betaine content after 4 h of exposure to low salinity, suggesting tissue-specific variability in the cellular response to salinity change. The consistent lack of a short-term RVD in many tissues may serve to avoid large energetic expenditures associated with repeated volume regulation in the face of the frequent, short-term changes in salinity encountered by estuarine mussels.

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