Ecological implications of artificial mixing and bottom-sediment removal for a shallow urban lake, Lake Sheldon, Colorado

2007 ◽  
Vol 12 (2) ◽  
pp. 73-86 ◽  
Author(s):  
P. J. Oberholster ◽  
A-M. Botha ◽  
T. E. Cloete
Keyword(s):  
Bottom Sediment ◽  
Urban Lake ◽  
Sediment Removal ◽  
Artificial Mixing ◽  
Ecological Implications

Behaviour and Ecology of the Dugong, Dugong Dugon (Sirenia): Observations in Shoalwater and Cleveland Bays, Queensland.

1978 ◽  
Vol 5 (1) ◽  
pp. 1 ◽  
Author(s):  
PK Anderson ◽  
A Birtles
Keyword(s):  
Bottom Sediment ◽  
Random Sample ◽  
Seagrass Species ◽  
Faecal Pellets ◽  
Sediment Removal ◽  
Plant Fibre ◽  
Sea Grass ◽  
Common Activity ◽  
Zostera Capricorni

Dugongs (Dugong dugon) were studied in 2 bays in north Queensland from shore and small boats. Population in favoured areas of one bay was 5/km shoreline and 4 to 8% were juveniles. Feeding was the most common activity. The dugongs dived and grazed, apparently using their rostral disc to gouge a serpentine track through the bottom sediment. Removal of sea grass was calculated to be 78% from the tracks selected by observers or 59% from a random sample; both were thought to be underestimated. Dugongs tended to move on after 5 or 6 days when 30% of an area had been grazed. They left inshore sea grass beds before low tide to avoid being stranded, so their feeding was governed by the 25-h cycle of 2 high and 2 low tides daily. Inshore feeding was not restricted to hours of darkness. The most commonly eaten sea grasses were Zostera capricorni, Halophila decipiens and H. ovalis. From published work, it was thought that the dugongs specialized in whatever seagrass species were most readily available. Owing to opacity of the water, they could not be observed under water. Mean length of the 9 faecal pellets found on shore was 8.98 mm; the pellets included plant fibre.

ANALYSIS OF ACCUMULATION AND DISTRIBUTION OF LEAD IN THE SYSTEM WATER-BOTTOM SEDIMENTS IN THE BACH DANG ESTUARY (VIETNAM)

2017 ◽  
pp. 62-66
Author(s):  
Truong Van Tuan ◽  
Irina Vladimirovna Volkova
Keyword(s):  
Bottom Sediment ◽  
Bottom Sediments ◽  
Water Samples ◽  
Suspended Solids ◽  
Natural Habitat ◽  
Bottom Layer ◽  
Sediment Samples ◽  
Natural Breeding ◽  
System Water ◽  
Water Bottom

Research was held in the estuary of the river Bach Dang (Dongbay community, Rakhtay district, Hai Phong, Vietnam) in June, 2012 - May, 2013. Concentration of lead was studied in water, suspended solids and bottom sediment. Clam beach (natural breeding environment of Meretrix lyrata ) was inspected regularly, every month. Water samples were taken 6 times from the bottom layer 10 cm down the bottom, once per 3 hours in each of 12 investigated zones. Bottom sediment samples were taken at the depth 2 cm. The findings show that lead accumulates mainly in suspended solids (23.3 mg/kg) and in bottom sediment (14.31 mg/kg), in water it is in small quantities (0.003 mg/kg). Analysis of bottom sediment samples taken in different places showed that they have even leadcontent, lead is distributed uniformly, localization of contaminations is not found. The results obtained can be assumed as the basis for investigating lead accumulation and its excretion by clam Meretrix lyrata organisms in the natural habitat.

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