scholarly journals Spatial and temporal patterns of fish assemblages in mountain streams of the Ren River, southwest China

2021 ◽  
Author(s):  
Fei Liu ◽  
Pengcheng Lin ◽  
Huanzhang Liu ◽  
Jun Wang
Keyword(s):  
Fish Assemblage ◽  
Large Scale ◽  
Southwest China ◽  
Fish Assemblages ◽  
Cold Water ◽  
Temporal Patterns ◽  
Mountain Streams ◽  
Small Scale ◽  
Spatial And Temporal Patterns ◽  
Landscape Factors

The spatial-temporal patterns of fish assemblages in lotic systems can provide useful information in developing effective conservation measures. This study aimed to explore the spatiotemporal changes in fish assemblage and their association with environmental factors in mountain streams of Ren River, southwest China. Filed investigations were conducted at 18 sites during rainy and dry season in 2017. A total of 21 species, belonged to 3 orders, 8 families and 19 genera, were collected. Analysis of similarities (ANOSIM) showed fish assemblages structure varied significantly at the spatial scale, but not at the temporal scale. In low order sites, fish assemblages were mainly dominated by cold water and rheophilic species (e.g. Rhynchocypris oxycephalus, Scaphesthes macrolepis, Metahomaloptera omeiensis and Gnathopogon herzensteini), while those in high order sites were predominated by warm water and eurytopicity or stagnophilic species (e.g. Squalidus argentatus, Hemiculter leucisculus and Zacco platypus). Canonical correspondence analysis (CCA) showed fish assemblages were structured by a combination of large-scale landscape factors (e.g. altitude and C-link) and small-scale habitat features (e.g. channel width, water temperature and depth). Among these factors, landscape factors had the greatest influence on fish assemblage, while local habitat measures played less important roles or just acted in certain season.

Variation in algal assemblages on wave-exposed rocky shores in New South Wales

1998 ◽  
Vol 49 (3) ◽  
pp. 241 ◽  
Author(s):  
A. J. Underwood ◽  
M. G. Chapman
Keyword(s):  
Large Scale ◽  
New South ◽  
New South Wales ◽  
Temporal Patterns ◽  
Explanatory Models ◽  
Small Scale ◽  
Rocky Shores ◽  
Spatial And Temporal Patterns ◽  
South Wales ◽  
Algal Assemblages

Data were collected in New South Wales from replicate sites on five wave-exposed shores separated by hundreds of kilometres at three-monthly intervals for four years, to examine large and small spatial and temporal patterns in low-shore algal assemblages. These data were used to test hypotheses from the models that algal assemblages show large-scale, predictable changes in structure or, alternatively, that variation from time to time is small-scale and differs from shore to shore or site to site on a shore. There was considerable variation at all scales examined — among replicate quadrats within sites, between sites on a shore and among shores. Similarly, assemblages differed from one sampling period to the next and changes in the assemblages over time periods of three months were as great as from year to year. These changes were interactive, with no two sites or shores showing similar temporal patterns. Thus, understanding diversity along a coast-line requires detailed understanding of local processes. Without adequate spatial and temporal replication in sampling designs and without explanatory models, the large and complex variability in intertidal assemblages at different scales cannot be documented and understood.

Experimental Investigation of Lab-Scale, Heat Exchanger Prototypes Designed to Provide Refugia for Trout

2021 ◽  
Author(s):  
Rajib Uddin Rony ◽  
Adam Gladen ◽  
Sarah LaVallie ◽  
Jeremy Kientz
Keyword(s):  
Heat Exchanger ◽  
Temperature Difference ◽  
Large Scale ◽  
Cold Water ◽  
Cooling System ◽  
Tube Bundle ◽  
Small Scale ◽  
Scaled Model ◽  
Average Temperature ◽  
Average Temperature Difference

Abstract In recent years Spring Creek in South Dakota, a popular fishing location, has been experiencing higher surface water temperatures, which negatively impact cold-water trout species. One potential solution is to provide localized refugia of colder water produced via active cooling. The present work focuses on the design and testing of a small-scale prototype heat exchanger, for such a cooling system. Various prototypes of the heat exchanger were tested in a 1/10th-scaled model of a section of the creek. A staggered, tube-bundle heat exchanger was used. The prototypes consisted of just the heat exchanger placed directly in the scaled-stream model and of the heat exchanger placed inside an enclosure with an aperture. The results show that, without the enclosure, the average temperature difference is 0.64 °C, with a corresponding heat transfer requirement of 1.63 kW/°C of cooling. However, with an enclosure, the average temperature difference is 1.95 °C, which required 0.59 kW/°C of cooling. Modifications to the enclosure decrease the average temperature difference but also decrease the standard deviation of the temperature difference. Thus, the cooling effect is more evenly spread throughout the water in the enclosure. This indicates that the enclosure design can be used to balance the requirements of obtaining a desired temperature difference with a relatively low spatial variation in that temperature difference. These results will be used to guide the design of the large-scale heat exchanger prototype.

Spatial and temporal patterns of changing vegetation and the influence of environmental factors in the karst region of Southwest China

2018 ◽  
Vol 38 (24) ◽  
Author(s):  
吕妍 LÜ Yan ◽  
张黎 ZHANG Li ◽  
闫慧敏 YAN Huimin ◽  
任小丽 REN Xiaoli ◽  
王军邦 WANG Junbang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Southwest China ◽  
Temporal Patterns ◽  
Karst Region ◽  
Spatial And Temporal Patterns

scholarly journals Spatial and temporal patterns of stream fish assemblages within Taihu Basin

2016 ◽  
Vol 28 (6) ◽  
pp. 1371-1380
Author(s):  
LI Qifang ◽  
◽  
YAN Yunzhi ◽  
CHU Ling ◽  
ZHU Ren ◽  
...  
Keyword(s):  
Fish Assemblages ◽  
Temporal Patterns ◽  
Stream Fish ◽  
Spatial And Temporal Patterns ◽  
Taihu Basin ◽  
Stream Fish Assemblages

Small-scale spatial and temporal patterns in spawning of Atlantic cod (Gadus morhua) in coastal Newfoundland waters

2000 ◽  
Vol 57 (5) ◽  
pp. 1011-1024 ◽  
Author(s):  
Gareth L Lawson ◽  
George A Rose
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Temporal Patterns ◽  
Small Scale ◽  
Spatial And Temporal Patterns ◽  
Spawning Grounds ◽  
Acoustic Surveys ◽  
Placentia Bay ◽  
June July ◽  
Timing Of Spawning

Acoustic surveys were used to locate coastal Atlantic cod (Gadus morhua) spawning grounds and examine spatial and temporal patterns of spawning in Placentia Bay, Newfoundland, Canada. The same three grounds were used in 1997 and 1998 (Bar Haven in the inner bay and Cape St. Mary's and Oderin Bank in the outer bay). Grounds had densities >0.1 fish·m-2 over scales of 100 m and >13% of mature females in spawning condition. Ground use and spawning timing differed between years. Mean spawning female densities were highest at Cape St. Mary's in 1997 (1.6 × 10-2 fish·m-2) and Oderin Bank in 1998 (1.0 × 10-2 fish·m-2). At all grounds, spawning peaked earlier in 1997 (April) than in 1998 (June-July). In both years, cod spawned at sub- or near-zero temperatures. "Spawning columns" were observed at sites and times having high densities of spawning females. Sex ratios suggested that males arrived first and stayed later, while females followed when ready to spawn, accompanied by juveniles. Older females spawned earlier and later than younger females. Peaks in density of spawning females and the proportion of females spawning did not coincide. Hence, the location and timing of spawning cannot be quantified solely from the proportions of females in spawning condition.

Response of demersal fish assemblages to an extreme flood event in a freshwater-deprived estuary in South Africa

2018 ◽  
Vol 69 (2) ◽  
pp. 253 ◽  
Author(s):  
P. Nodo ◽  
N. C. James ◽  
A.-R. Childs ◽  
M. D. V. Nakin
Keyword(s):  
South Africa ◽  
Fish Assemblage ◽  
Large Scale ◽  
Fish Assemblages ◽  
Salinity Gradient ◽  
Demersal Fish ◽  
Flood Event ◽  
Estuarine Fish ◽  
Water Abstraction ◽  
Extreme Flood

The Kariega Estuary in South Africa, is an example of a freshwater-deprived estuary. Large-scale water abstraction and droughts have resulted in this estuary either being uniformly marine or hypersaline. A major episodic flood event in October 2012, the largest ever recorded in this system, provided us with an opportunity to investigate the prolonged effect of an episodic flood on the demersal fish assemblage of a freshwater-deprived estuary. A beam trawl net was used for sampling the fish assemblages from December 2013 to November 2014. The flood event before the sampling period ‘reset’ the system, such that there was a longitudinal salinity gradient from the head to the mouth, which resulted in ‘normal’ estuarine conditions, typical of most estuaries. There was an increase in the abundance of benthopelagic marine migrant species, particularly early juveniles of important fishery species, in the middle and upper reaches during the present study relative to previous studies conducted in this freshwater-deprived system. This suggests increased recruitment of these species into their estuarine nursery habitat. The present study highlights the importance of understanding the effect of freshwater inflow on the demersal estuarine fish assemblage and the nursery role of this and other estuarine systems and their management.

Controls on fish distribution and abundance in temporary wetlands

2002 ◽  
Vol 59 (9) ◽  
pp. 1441-1450 ◽  
Author(s):  
Matthew J Baber ◽  
Daniel L Childers ◽  
Kimberly J Babbitt ◽  
David H Anderson
Keyword(s):  
Large Scale ◽  
Fish Assemblages ◽  
Fish Distribution ◽  
Temporary Ponds ◽  
Small Scale ◽  
Cattle Ranching ◽  
Temporary Wetlands ◽  
Local Characteristics ◽  
Landscape Processes ◽  
Colonization Dynamics

Our main goal was to determine if fish distribution and adundance in temporary wetlands were shaped primarily by large-scale (landscape) or small-scale (local) characteristics and to investigate the influence of cattle ranching on fish assemblages. A total of 24 temporary ponds were selected at the Kissimmee Prairie Sanctuary and the Mac Arthur Agro-Ecology Research Center. Each wetland was sampled for fish using throw traps and dip nets during 1999. Landscape processes (connectivity to permanent water bodies) predominately influenced fish assemblages, although local processes (depth–hydroperiod) were also important. Furthermore, no colonizing species went locally extinct before wetlands began to dry. Our findings suggest that large-scale processes that influence colonization dynamics are of more importance than small-scale processes that influence extinction dynamics. Finally, hydrological changes (ditching) associated with agriculture (cattle ranching) have adversely affected temporary wetland fish assemblages by reducing wetland hydroperiods and connectivity.

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