A MASS MORTALITY OF FISH ASSOCIATED WITH LOW SALINITY CONDITIONS IN THE BOT RIVER ESTUARY

1985 ◽  
Vol 45 (3-4) ◽  
pp. 437-447 ◽  
Author(s):  
B. A. Bennett
Keyword(s):  
River Estuary ◽  
Mass Mortality ◽  
Low Salinity

scholarly journals Discovery of Euryhaline Phycoerythrobilin-Containing Synechococcus and Its Mechanisms for Adaptation to Estuarine Environments

mSystems ◽  
2020 ◽  
Vol 5 (6) ◽  
pp. e00842-20
Author(s):  
Xiaomin Xia ◽  
Puiyin Lee ◽  
Shunyan Cheung ◽  
Yanhong Lu ◽  
Hongbin Liu
Keyword(s):  
Molecular Mechanisms ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Estuarine Environment ◽  
Pearl River ◽  
Niche Separation ◽  
Whole Genome Analysis ◽  
Low Salinity ◽  
The Pearl River Estuary ◽  
The Pearl River

ABSTRACTSynechococcus are among the most abundant and widely distributed picocyanobacteria on earth. Cluster 5 phycoerythrobilin-containing (PEB-containing) Synechococcus, the major marine Synechococcus, were considered to prefer high salinity, and they are absent in estuarine ecosystems. However, we have detected PEB-containing Synechococcus in some low-salinity (<15-ppt) areas of the Pearl River estuary at an abundance up to 1.0 × 105 cells ml−1. Two PEB-containing Synechococcus strains (HK01 and LTW-R) were isolated, and tests on them revealed their ability to cope with variations in the salinity (from 14 to 44 ppt). Phylogenetic analysis showed that HK01 belonged to a novel Synechococcus clade (HK1), whereas LTW-R was clustered with S5.2 strains. Whole-genome analysis revealed that a membrane channel protein with glycine zipper motifs is unique to euryhaline Synechococcus. The upregulation of this protein, the osmotic sensors, and the heat shock protein HSP20 and the downregulation of the osmolyte biosynthesis enable euryhaline Synechococcus to well adapt to the low and fluctuating salinity in the estuarine environment. In addition, decreasing the salinity in LTW-R strongly downregulated several important metabolic pathways, including photosynthesis, and the Calvin-Benson cycle, whereas its growth was not significantly affected. Moreover, obtaining PEB genes from horizontal gene transfer expands the light niche significantly for euryhaline Synechococcus. These results provided new insights into the life strategies and ecological function of marine PEB-containing Synechococcus under the unique environmental condition of estuarine waters, particularly in response to salinity variations.IMPORTANCE Understanding the strategies developed by different microbial groups to adapt to specific niches is critical. Through genome and transcriptome analyses of two newly isolated novel euryhaline Synechococcus strains, this study revealed that cluster 5 phycoerythrobilin-containing Synechococcus, which are thought to be strictly marine strains, could be abundant in low-salinity waters of the Pearl River estuary (salinity <15 ppt) and explained the molecular mechanisms that enabled them to adapt the low and fluctuating salinity in the estuarine environment. This study expands current understanding on mechanisms involved in niche separation of marine Synechococcus lineages.

scholarly journals Distribution and Size of Barnacle Chelonibia patula Fouling Blue Crab Callinectes amnicola in Southeast Nigeria

2016 ◽  
Vol 74 (3) ◽  
pp. 93-102
Author(s):  
James Philip Udoh ◽  
Aniekan Johnny Otoh
Keyword(s):  
Public Health ◽  
Spatial Distribution ◽  
Health Risk ◽  
Blue Crab ◽  
Carapace Width ◽  
River Estuary ◽  
Wet Season ◽  
Low Salinity ◽  
Host Interaction ◽  
Significant Difference

Abstract The distribution and occurrence of epibionts on the dorsal carapace, ventral carapace and chela of 325 specimens of Callinectes amnicola (De Rocheburne, 1883) (103.4 - 138.7 mm carapace width) from the Qua Iboe (QIRE) and Imo River (IRE) estuaries in southeast Nigeria was determined. The only ectosymbiont observed was cirriped barnacle, Chelonibia patula, mostly of smaller sizes (2.25 mm), infesting only 25-29% of intermoult crabs, more on females and in the Imo River estuary, with an average of four barnacles per crab, presupposing low level of epibiont-host interaction. There was no significant difference (P>0.05) in spatial distribution but epibionts were highest in the dry season in low salinity IRE (0.53‰) and in wet season in the medium-salinity QIRE (17.4‰). No public health risk has been reported among crab consumers in the study area. This study highlights epibiont-host interaction in the study area largely unknown for proper management of the fishery.

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.

Anomalous Occurrence of Carp (Cyprinus carpio) in the Marine Environment

1971 ◽  
Vol 28 (9) ◽  
pp. 1345-1347 ◽  
Author(s):  
W. E. Barraclough ◽  
D. G. Robinson
Keyword(s):  
British Columbia ◽  
Marine Environment ◽  
Surface Waters ◽  
Cyprinus Carpio ◽  
River Estuary ◽  
Vancouver Island ◽  
Fraser River ◽  
Strait Of Georgia ◽  
Low Salinity ◽  
Carp Cyprinus Carpio

Juvenile carp (Cyprinus carpio) were caught with a surface trawl in low salinity surface waters of the Strait of Georgia, British Columbia, during July 1967. A natural environmental route is established for the possible movement of carp from the Fraser River estuary to watersheds on Vancouver Island.

scholarly journals Nutrient and phytoplankton biomass in the Amazon River shelf waters

2008 ◽  
Vol 80 (4) ◽  
pp. 703-717 ◽  
Author(s):  
Maria L.S. Santos ◽  
Kátia Muniz ◽  
Benício Barros-Neto ◽  
Moacyr Araujo
Keyword(s):  
River Flow ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
Amazon River ◽  
Shelf Area ◽  
Particulate Nitrogen ◽  
Dissolved Nitrogen ◽  
Low Salinity ◽  
High Nutrient ◽  
High River Flow

The Amazon River estuary is notable at the Amazon Continental Shelf, where the presence of the large amount of water originating from the Amazon during the river's falling discharge period was made evident by the low salinity values and high nutrient levels. Even so, the presence of oceanic waters in the shelf area was significant. Dissolved organic nitrogen was the predominant species of the nitrogen cycle phases, followed by total particulate nitrogen, nitrate, ammonium and nitrite. The chlorophyll a data in the eutrophic area indicated that there is sufficient nitrogen in the area to withstand productivity, though dissolved inorganic nitrogen removal processes are faster than regeneration or mineralization. The anomalous amounts of inorganic dissolved nitrogen showed more removal than addition. The simulations with the bidimensional MAAC-2D model confirmed that high nutrient waters are displaced northwest-ward (two cores at 2.5ºN-50ºW and 4ºN-51ºW) by the stronger NBC during falling river discharge. During high river flow period these nutrient-rich lenses are distributed around 0.5ºN-48.5ºW as well as along the shallow Amazonian shelf (20m-50m depth, 1ºN-3.5ºN), as a result of the spreading of Amazon freshwater outflow.

Records from Marsh Foraminifera and Grapevine Growing Season Temperatures Reveal the Hydro-climatic Evolution of the Minho Region (nw Portugal) from 1856–2009

2017 ◽  
Vol 47 (2) ◽  
pp. 208-218 ◽  
Author(s):  
João Moreno ◽  
Francisco Fatela ◽  
Eduardo Leorri ◽  
Filipa Moreno
Keyword(s):  
Tidal Marsh ◽  
Large Scale ◽  
Climatic Variability ◽  
Oscillation Mode ◽  
River Estuary ◽  
Growing Season ◽  
Precipitation Anomaly ◽  
Climatic Conditions ◽  
Low Salinity ◽  
Nw Portugal

Abstract A hydro-climatic reconstruction is proposed for the Minho region (NW Portugal), integrating two different proxies: grape harvest dates (GHD) as a proxy of temperature variations, and benthic marsh foraminifera as a proxy of salinity of sediment interstitial waters. The reconstructed and measured mean maximum temperatures (GSTmax) of grapevine-growing season (March to August) were combined with data on benthic foraminiferal assemblages from the Caminha tidal marsh (Minho River estuary) to characterize the main hydro-climatic episodes in the region during the last 154 years. Results emphasize that, in the brackish setting of the Minho estuary, where foraminiferal species usually associated with low salinity occur, higher GSTmax had an impact on the hydrological balance of the marsh by enhancing evapotranspiration and increasing interstitial salinity. These conditions favored the occurrence of marsh species such as Jadammina macrescens and Trochammina inflata. The influence of the North Atlantic European meteorological teleconnection patterns on recent climatic variability of the Minho region was also examined from 1950–2009. Data support the hypothesis that persistent positive modes of spring-summer Scandinavian Oscillation Mode (SCA) and summer Eastern Atlantic/ Western Russia Oscillation Mode (EA/ WR) patterns triggered lower GSTmax, especially in the 1960s–1980s. Those conditions, in-phase with a positive precipitation anomaly (1958–1983), reduced the Caminha tidal marsh salinity, leading to the increase of low salinity species: Trochamminita salsa/irregularis, Haplophragmoides manilaensis, Miliammina fusca and Miliammina spp. Both proxies provide valuable tools for understanding the interactions between large-scale circulation modes and hydro-climatic conditions at regional and local scales.

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