Is it possible to predict habitat use by spawning salmonids? A test using California golden trout (Oncorhynchus mykiss aguabonita)

1999 ◽  
Vol 56 (9) ◽  
pp. 1576-1584 ◽  
Author(s):  
Roland A Knapp ◽  
Haiganoush K Preisler

It is widely believed that stream salmonids select spawning sites based on water depth, water velocity, and substrate size. Attempts to predict spawning locations using these habitat features have met with little success, however. In this study, we used nonparametric logistic regression to determine what habitat features were associated with the locations chosen by spawning California golden trout (Oncorhynchus mykiss aguabonita). From this nonparametric model, we developed a parametric model that incorporated the habitat features most strongly associated with spawning sites and used this model to calculate the probability of use by spawning golden trout for specific stream locations. The overall nonparametric model was highly significant and explained 62% of the variation in spawning location. Four of the eight habitat variables, substrate size, water depth, water velocity, and stream width, had highly significant effects and alone explained 59% of the variation in spawning location. The results of a cross-validation procedure indicated that the parametric model generally provided a good fit to the data. These results indicate that location-specific probabilities of use were predictable based on easily measured habitat characteristics and that nonparametric regression, an approach still rarely used in ecological studies, may have considerable utility in the development of fish-habitat models. Given the escalating pace at which fish habitats are being altered, such models are increasingly important in predicting the effects of these alterations on populations.


2011 ◽  
Vol 340 ◽  
pp. 480-486
Author(s):  
Ding Long Li ◽  
Hong Lu ◽  
Qian Chen ◽  
Jian Ying Chao ◽  
Xiang Ji Kong ◽  
...  

Removal properties are researched and discussed of algae and nitrogen & phosphorus nutrients with periphyton by assembled substrate in lake-based eutrophic water body, including impacts on removal effects of several physical & chemical properties as water depth, water velocity, DO, temperature and PH. The results show that: the removal rate of NH4-N, other nitrogen nutrients, phosphorus nutrients and Chl-a were 96%, 40%, 80%, 65% respectively. With the growth of water velocity(from 0 to 200L/h ), the removal of Chl-a, TP, TDP increased to a certain extent(Chl-a: from 63.63% to 67.66%; TP:from 76.15% to 85.13%;TDP:from 80.10% to 88.44%),and that of TN,TDN and NO3-N decreased to different extents(TN: from 45.19% to 31.97%; TDN: from 42.81% to 28.77%; NO3-N: from 38.11% to –5.26%), but that of NH4-N and PO4-P altered little(NH4-N:from 96.80% to 95.94%;PO4-P:from 85.38% to 87.02%). It will provide reference for recovery and re-contribution of destroyed Eco-system, and a new thought for treatment in eutrophical lakes.



2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mustafa B. Al-Deen ◽  
Mazin Ali A. Ali ◽  
Zeyad A. Saleh

Abstract This paper presents a new approach to discover the effect of depth water for underwater visible light communications (UVLC). The quality of the optical link was investigated with varying water depth under coastal water types. The performance of the UVLC with multiple input–multiple output (MIMO) techniques was examined in terms of bit error rate (BER) and data rate. The theoretical result explains that there is a good performance for UVLC system under coastal water.



2010 ◽  
Vol 21 (1) ◽  
pp. 59-71 ◽  
Author(s):  
JESÚS CARO ◽  
DIEGO ONTIVEROS ◽  
MANUEL PIZARRO ◽  
JUAN M. PLEGUEZUELOS

SummaryBonelli’s Eagle Hieraaetus fasciatus and Golden Eagle Aquila chrysaetos are two declining species, in which floaters tend to be located outside of breeding territories during the dispersal period, in so-called settlement areas. We studied settlement areas for both these long-lived raptors in the southern Iberian Peninsula, to gain a better understanding of the ecological requirements of the eagles during their long pre-adult stage, a period accounting for around 80% of the species’ mortality. Eagle abundance was calculated by road censuses, and habitat characteristics of settlement and non-settlement areas compared by General Discriminant Analysis (GDA) and Logistic Regression (LR). The best model of GDA and LR incorporated the abundance of main prey for eagles (rabbits, partridges) and orchard surface area, and explained 100% of eagle presence; the best model selected by GDA also included habitat heterogeneity. Both eagles tended to share settlement areas in the southern Iberian Peninsula and, when they did not, the mean annual temperature and slope appeared to explain the segregation between the two species. Management measures for the conservation of both threatened species during the dispersal period should be focused on identifying settlement areas, maintaining high prey densities and maximum habitat heterogeneity.



2019 ◽  
Vol 48 (No. 9) ◽  
pp. 415-424 ◽  
Author(s):  
M. Saniga

Habitat characteristics of 43 capercaillie (Tetrao urogallus) leks were studied in the mountains of Central Slovakia (West Carpathians) in 1984–2002. Macro-habitat was described with respect to topography and succession stage. Micro-habitat was described with respect to forest type and forest stand structure. Twenty-seven out of forty-three display grounds were situated in the upper half of the lateral ridges. Sixteen leks were located on hills of the lateral ridges (slope < 10%). All the leks were situated in old succession stages of the forest (80–200 years old). Twenty-seven display grounds were located in natural forests, sixteen leks were situated in man-managed stands more than 80 years old. Leks were situated in a variety of forest types with overstorey tree-density between 400–1,050 stems per ha. Distribution of leks was limited above all by macro-habitat characteristics (elevated sites, old stands). Age-space structure seemed to be a significant micro-habitat feature (preference of multi-layered stands).  



2010 ◽  
Vol 67 (6) ◽  
pp. 919-935 ◽  
Author(s):  
P. Tamkee ◽  
E. Parkinson ◽  
E. B. Taylor

Microsatellite DNA variation was examined in rainbow trout ( Oncorhynchus mykiss ) populations from throughout British Columbia, Canada, to address the roles of historical isolation, postglacial dispersal, and contemporary geomorphology in structuring genetic variation and differentiation. We detected signatures of historical isolation and postglacial recolonization in the form of “interior” and “coastal” population groupings, a decline in genetic variation as distance increased from putative glacial refugia, and different extents of isolation-by-distance in different regions. Rainbow trout populations were structured genetically into major regions and into smaller watersheds and then into drainages. Within drainages, high levels of dispersal and gene flow were inferred between geographically proximate and contiguous lakes. Elevation, stream branching points (nodes), fluvial distance, migration barriers, and stream and lake order influenced genetic diversity within, and differentiation among, populations. Habitat characteristics, particularly lake surface area and perimeter, were poor predictors of genetic variation. Although founder events and postglacial dispersal influenced broadscale patterns of genetic diversity in rainbow trout, our results suggest that contemporary factors can strongly modulate historical patterns.



2008 ◽  
Vol 65 (2) ◽  
pp. 266-275 ◽  
Author(s):  
John J Piccolo ◽  
Nicholas F Hughes ◽  
Mason D Bryant

We examined the effects of water velocity on prey detection and capture by drift-feeding juvenile coho salmon (Oncorhynchus kisutch) and steelhead (sea-run rainbow trout, Oncorhynchus mykiss irideus) in laboratory experiments. We used repeated-measures analysis of variance to test the effects of velocity, species, and the velocity × species interaction on prey capture probability, prey detection distance, and swimming speeds during prey capture. We used 3D video analysis to assess the spatial and temporal characteristics of prey detection and capture. Coho and steelhead showed significant, velocity-dependent decreases in capture probability (~65% to 10%, with an increase of velocity from 0.29 to 0.61 m·s-1) and prey detection distance, with no effect of species and no velocity × species interaction. Neither velocity nor species affected prey interception speed; fish intercepted prey at their predicted maximum sustainable swimming speed (Vmax) at all velocities. Speed of return to the focal point increased significantly with increasing velocity, with no effect of species. At faster velocities, return speeds were faster than Vmax, indicating potential increases in energetic cost because of anaerobic swimming. The 3D analysis suggests that the reduction in capture probability was due to both reduced prey detection distance and a uniform decline in detection probability within the prey capture area.



2013 ◽  
Vol 70 (5) ◽  
pp. 756-765 ◽  
Author(s):  
Barry A. Berejikian ◽  
Lance A. Campbell ◽  
Megan E. Moore

Juvenile Oncorhynchus mykiss maternity was determined from otolith strontium:calcium ratios to investigate the degree of anadromy in eight freshwater streams draining to a common fjord. The percentages of O. mykiss parr produced by anadromous females ranged from an annual average of 41.3% (Hamma Hamma River) to 100% (Dewatto River). The proportion of stream habitat available to resident O. mykiss upstream of barriers to anadromous migration explained a significant portion of the variability in maternal life history below barrier falls and was included in each of the five logistic regression models with the lowest AIC scores. Transitional hydrologic profiles, low mean annual temperatures and high mean annual stream flow, common to Olympic Peninsula streams, were each associated with greater proportions of offspring from resident females. Only 2 out of 234 parr from the lowland, rain-driven, low-flow streams of the Kitsap Peninsula were produced by resident females. Thus, large-scale habitat features, and primarily the presence or absence of resident populations above natural barriers to anadromous migration, appeared to shape the degree of anadromy among populations.



2000 ◽  
Vol 57 (10) ◽  
pp. 2152-2162 ◽  
Author(s):  
Christian E Zimmerman ◽  
Gordon H Reeves

Reproductive isolation between steelhead and resident rainbow trout (Oncorhynchus mykiss) was examined in the Deschutes River, Oregon, through surveys of spawning timing and location. Otolith microchemistry was used to determine the occurrence of steelhead and resident rainbow trout progeny in the adult populations of steelhead and resident rainbow trout in the Deschutes River and in the Babine River, British Columbia. In the 3 years studied, steelhead spawning occurred from mid March through May and resident rainbow trout spawning occurred from mid March through August. The timing of 50% spawning was 9-10 weeks earlier for steelhead than for resident rainbow trout. Spawning sites selected by steelhead were in deeper water and had larger substrate than those selected by resident rainbow trout. Maternal origin was identified by comparing Sr/Ca ratios in the primordia and freshwater growth regions of the otolith with a wavelength-dispersive electron microprobe. In the Deschutes River, only steelhead of steelhead maternal origin and resident rainbow trout of resident rainbow trout origin were observed. In the Babine River, steelhead of resident rainbow trout origin and resident rainbow trout of steelhead maternal origin were also observed. Based on these findings, we suggest that steelhead and resident rainbow trout in the Deschutes River may constitute reproductively isolated populations.



1984 ◽  
Vol 41 (3) ◽  
pp. 469-475 ◽  
Author(s):  
D. M. Rimmer ◽  
U. Paim ◽  
R. L. Saunders

Over three summers we used direct underwater observation to examine the summer to autumn differences in seven microhabitat properties of three age-classes of juvenile Atlantic salmon (Salmo salar) in the Little Sevogle River of northeastern New Brunswick. Salmon of all three age-classes occupied a wide range of water depths during summer, but were concentrated mainly in depths of 24–36 cm. In autumn, they occurred in this range almost exclusively. The streambed stones most closely associated with the individual positions of all ages were always <20 cm in summer and mostly (84–92%) <10 cm in diameter. In autumn, all ages were associated with home stones up to 40 cm in diameter, with 65–83% of the stones exceeding 20 cm; the size of home stones selected increased with fish age in autumn. There was no apparent relationship between the water depth and home stone size distributions occupied by all age-classes and available in the stream during either summer or autumn. Summer focal water velocity (velocity at the fish's snout) was predominantly 10–30 cm∙s−1 for 0+, 10–40 cm∙s−1 for 1+, and 30–50 cm∙s−1 for 2+ salmon, but during autumn it was almost always <10 cm∙s−1 for all ages. The bottom and surface water velocities as well as the maximum water velocity within 1 m of fish stations increased with fish age during summer and autumn. At the summer–autumn transition, 0+ salmon selected higher bottom, surface, and maximum water velocities, 2+ salmon selected lower velocities, but selection by 1+ salmon remained unchanged. We view substrate size followed by water depth as the primary properties influencing stream suitability for juvenile Atlantic salmon in autumn.



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