A Sandy Area in the Dovey Estuary

1940 ◽  
Vol 28 (2) ◽  
pp. 453 ◽  
Author(s):  
J. M. Lambert ◽  
M. R. Davies
Keyword(s):  
Sandy Area

Đặc điểm của thảm thực vật vùng đất cát nội đồng ngập nước tại huyện Phong Điền tỉnh Thừa Thiên Huế

2019 ◽  
Vol 127 (4A) ◽  
pp. 53-63
Author(s):  
Truong Hieu Thao ◽  
Hoang Ho Dac Thai
Keyword(s):  
Species Composition ◽  
Site Condition ◽  
Sandy Area ◽  
Shrub Community ◽  
Peat Swamp ◽  
Study Sites

Thảm thực vật vùng đất cát nôi đồng ngập nước theo mùa tại huyện Phong Điền tỉnh Thừa Thiên Huế dựa vào cấu trúc tổ thành được phân thành 4 quần xã đó là: Quần xã cỏ ẩm nằm ven các trằm; Quần xã cây bụi trên vùng cát trũng; Quần xã Tràm trên vùng ngập nước thường xuyên và định kỳ; Quần xã cây gỗ lớn trên đầm lầy than bùn.Mỗi một quần xã đặc trưng bởi một nhóm loài thực vật ưu thế khác nhau, cấu trúc khác nhau đặc thù cho dạng lập địa tạo nên sự đa dạng về thực vật vùng cát nói chung, và vùng đất cát nội đồng ngập nước nói riêng. Những kết quả đã đạt được là cơ sở dữ liệu về thực vật vùng cát, giúp cho công tác bảo tồn, phục hồi hệ sinh thái vùng cát sau này.Plants of submerged inner sandy area (coastal sandy and sandune areas) is divided 4 flora communities, they are Moist grasslands on the edge of the lake; Shrub community in low-lying inner sandy area; Melaleuca community on submerged inner sandy area and sandy seasonally inundated; Wood community on peat swamp, submerged inner sandy area. Site condition based causes flora communities with corresponding of species composition and ecological structures, make up the diversity of the submerged inner sandy flora system. These results contributed a database on the sandy plants for conservation, ecological based restoration in study sites.

Crypsis influences escape decisions in the Round-tailed Horned Lizard (Phrynosoma modestum)

2010 ◽  
Vol 88 (10) ◽  
pp. 1003-1010 ◽  
Author(s):  
William E. Cooper, ◽  
Wade C. Sherbrooke
Keyword(s):  
Body Temperature ◽  
Predation Risk ◽  
Upright Posture ◽  
Flight Initiation Distance ◽  
Lower Body ◽  
Running Speed ◽  
Predator Prey ◽  
Sandy Area ◽  
Lower Body Temperature ◽  
Flight Initiation

Flight initiation distance (predator–prey distance when escape begins) increases as predation risk increases. Prey should have longer flight initiation distance when their background, movement, or current posture reduces crypsis. Flight initiation distance of ectotherms may increase at lower body temperature to compensate for slower running speed. However, for cryptic prey, fleeing might increase the probability of being detected. The Round-tailed Horned Lizard ( Phrynosoma modestum Girard, 1852) is eucryptic and resembles small stones. We predicted that flight initiation distance by P. modestum is shorter among stones than on uniform sand. Because movement and upright posture disrupt crypsis, we predicted that flight initiation distance is greater after movement and when standing than when still and lying on the ground. As predicted, flight initiation distances were shorter on a rocky than sandy area, when lying flat than standing, and while immobile than after moving. We measured running speed and flight initiation distance to determine relationships among body temperature, speed, and escape decisions. Running speed and flight initiation distance were reduced at lower body temperature, suggesting that crypsis reinforced by immobility is more advantageous than longer flight initiation distance for cool, slow lizards. The lizards adjusted escape decisions to current effectiveness of crypsis and escape ability.

Parasitization of the white spotwrist hermit crab, Pagurus criniticornis (Dana, 1852) (Decapoda, Anomura), by the rhizocephalan barnacle Peltogasterella socialis (Müller, 1863) (Cirripedia, Rhizocephala) from southeastern Brazil

2007 ◽  
Vol 57 (3) ◽  
pp. 315-327 ◽  
Author(s):  
Fabíola Faria ◽  
Christopher Boyko ◽  
Fernando Mantelatto
Keyword(s):  
Size Distribution ◽  
Hermit Crab ◽  
Host Species ◽  
First Record ◽  
Species Description ◽  
Hermit Crabs ◽  
Southeastern Brazil ◽  
South American ◽  
The Bahamas ◽  
Sandy Area

AbstractHermit crabs of the species Pagurus criniticornis (Dana, 1852) parasitized by the poorly known colonial rhizocephalan Peltogasterella socialis (Müller, 1863), were collected in the infralittoral rocky/sandy area of Anchieta Island (São Paulo), Brazil. We report the presence and pattern of occurrence of this rhizocephalan in the P. criniticornis population. The hermit crabs were obtained monthly during 1999 by two people using SCUBA methods. A total of 992 hermit crabs were captured and examined for rhizocephalans. The studied population showed non-normal size distribution and only 2.11% of the sample specimens carried externae of P. socialis. The parasite occurrence was seasonal and varied with host size. Some signs of feminization were observed on P. criniticornis pleopods (elongation of the endopod and reduction of the exopod of pleopods for males and reduction in the size of endopods for females). This is the first report on this parasite/host relationship for this South American host species. This is the first record of P. socialis (Müller, 1863) subsequent to the species' description, and possible occurrence of the parasite on hermit crabs in the Bahamas is also reported.

scholarly journals Mapping Sandy Areas and their changes using remote sensing. A Case Study at North-East Al-Muthanna Province, South of Iraq

2021 ◽  
pp. 39
Author(s):  
Awad A. Sahar ◽  
Muaid J. Rasheed ◽  
Dhia A. A.-H. Uaid ◽  
Ammar A. Jasim
Keyword(s):  
Remote Sensing ◽  
Surface Temperature ◽  
Accuracy Assessment ◽  
Urban Life ◽  
Dynamic Features ◽  
Detection Techniques ◽  
Sandy Area ◽  
North East ◽  
South Of Iraq ◽  
Landsat Satellite

<p>Sandy areas are the main problem in regions of arid and semi-arid climate in the world that threaten urban life, buildings, agricultural, and even human health. Remote sensing is one of the technologies that can be used as an effective tool in dynamic features study of sandy areas and sand accumulations. In this study, two new indices were developed to separate the sandy areas from the non-sandy areas. The first one is called the Normalized Differential Sandy Areas Index (NDSAI) that has been based on the assumption that the sandy area has the lowest water content (moisture) than the other land cover classes. The second other is called the Sandy Areas Surface Temperature index (SASTI) which was built on the assumption that the surface temperature of sandy soil is the highest. The results of proposed indices have been compared with two indices that were previously proposed by other researchers, namely the Normalized Differential Sand Dune Index NDSI and the Eolain Mapping Index (EMI). The accuracy assessment of the sandy indices showed that the NDSAI provides very good performance with an overall accuracy of 89 %. The SASTI can isolate many sandy and non-sandy pixels with an overall accuracy about 86 %. The performance of the NDSI is low with an overall accuracy about 82 %. It fails to classify or isolate the vegetation area from the sandy area and might have better performance in desert environments. The performing of NDSAI that is calculated with the SWIR1 band of the Landsat satellite is better than the performing of NDSI that is calculated with the SWIR2 band of the same satellite. EMI performance is less robust than other methods as it is not useful for extracting sandy surfaces in area with different land covers. Change detection techniques were used by comparing the areas of the sandy lands for the periods from 1987 to 2017. The results showed an increase in sandy areas over four decades. The percentage of this increase was about 20 % to 30 % during 2002 and 2017 compared to 1987.</p>

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