Seasonal changes in the ratio of congeneric charrs in northern Japanese tributaries with different temperature regimes

doi:10.21203/rs.3.rs-2465444/v1

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Seasonal changes in the ratio of congeneric charrs in northern Japanese tributaries with different temperature regimes

https://doi.org/10.21203/rs.3.rs-2465444/v1

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Background: The species distributions and community compositions of stream fishes are often shaped by water temperature. Stream salmonids, for example, show longitudinal gradients or marked community differences between spring-fed vs. non-spring-fed streams, which may be a result of species-specific temperature preferences, interspecific competition, or their interaction (i.e., temperature-dependent competition). Despite the widely reported patterns, how such temperature-associated distributions change across seasons remains largely unknown. If temperature is the main driver, the pattern will change across seasons. Alternatively, seasonal patterns will be obscured if other factors, such as species-specific life histories or seasonal aggregation, are important. Here, we investigated the effects of water temperature on the abundance and species ratio of two potentially competing salmonids, southern Asian Dolly Varden Salvelinus curilus and white-spotted charr Salvelinus leucomaenis, in 6 small tributaries with different temperature regimes (i.e., spring-fed and non-spring-fed) across seasons.

Results: Across seasons, the southern Asian Dolly Varden dominated in spring-fed tributaries, whereas white-spotted charr dominated in non-spring-fed tributaries. The seasonal variation in the abundance of southern Asian Dolly Varden and species ratio were explained by water temperature fluctuation, whereas that of white-spotted charr was not explained by the temperature fluctuation. No winter aggregation was observed in any of the tributaries. In addition, only the species ratio in summer was explained by the water temperature, and the water temperature did not fully explain the species ratio.

Conclusions: Our results indicated that temperature preference and/or the strength of interspecific competition may differ across seasons, which is expected to determine the seasonal distribution patterns in spring-fed and non-spring-fed tributaries. This study underscores the importance of considering seasons when evaluating temperature effects on the distribution of stream salmonids.

thermal condition

species dominance

species interaction

seasonal migration

Salmonidae

Salvelinus

Understanding species distribution is a central theme in ecology. Stream salmonids show longitudinal distribution patterns [1–5] and marked community differences between spring-fed vs. non-spring-fed streams [6], which can be determined by species-specific temperature preferences, interspecific competition, or their interaction (i.e., temperature-dependent competition) [7–11]. For example, the southern Asian Dolly Varden Salvelinus curilus and white-spotted charr S. leucomaenis have different thermal requirements; foraging activities decline above 16°C for the former species and above 24°C for the latter species [12]. In addition, white-spotted charr are competitively dominant over the southern Asian Dolly Varden, but the dominance becomes weaker at a lower temperature [8, 13]. Thus, biotic and abiotic factors interactively shape the distribution patterns of potentially competing stream salmonids [14].

Despite the widely reported pattern, how such temperature-associated distributions change across seasons remains largely unknown. For example, if temperature is the main driver for a longitudinal distribution pattern, the transition or sympatric zone should move upstream (i.e., colder area at a higher altitude) in summer, whereas it shifts downstream in winter. This is analogous to the species range shift to higher altitudes caused by global warming [15–17]. We can also hypothesize that the species ratio will be stable across seasons in spring-fed streams where water temperature remains constant throughout the year [18, 19], whereas it changes seasonally in non-spring-fed streams. These patterns, however, would not be observed if factors other than temperature, such as water velocity, species-specific life histories, or seasonal aggregation, determine the longitudinal or spring vs. non-spring distributional patterns [e.g., 2]. Thus, seasonal changes in the distribution of potentially competing species should contribute to the understanding of coexistence mechanisms.

Here, we investigated the seasonal changes in the abundance and species ratio of two potentially competing salmonids, the southern Asian Dolly Varden and white-spotted charr, in 6 small tributaries with different temperature regimes (i.e., 2 spring-fed and 4 non-spring-fed) in the upper Sorachi River, Japan. As described above, we predicted a stable species ratio in tributaries with stable water temperature (i.e., spring-fed tributaries) across seasons, whereas tributaries with an unstable water temperature (i.e., non-spring-fed tributaries) showed an unstable species ratio. We took several steps to understand seasonal patterns in the abundance and ratio of the two species. First, we examined the dominant species and species ratio during the seasons. Second, we tested the relationship between the seasonal variation in water temperature and the seasonal variation in the abundance of southern Asian Dolly Varden and white-spotted charr and species ratio to clarify the effect of temperature stability on abundance and species ratio stability. Finally, we tested the relationship between the average water temperature and species ratio for each month. We were also interested in whether winter aggregation occurs more in spring-fed tributaries where the temperature is higher in winter [20, 21].

2.1 Field survey

The field survey was carried out in six tributaries of the upper Sorachi River system, central Hokkaido, Japan (Figure 1), where the southern Asian Dolly Varden and white-spotted charr coexist [6, 13]. In the study region, southern Asian Dolly Varden and white-spotted charr spawn in autumn ([22, 23] and I. Koizumi, unpublished data), and the fry of the two species emerge in spring (I. Koizumi, unpublished data). Two of the tributaries (T50.5 and KO) had typical spring-fed tributaries where groundwater consistently discharges, whereas three of them (T51, T61, and NGN) were typical runoff streams from precipitation flowing along valleys. Tributary T50 had multiple sources, i.e., spring spots and shallow underground water from the mainstem. We constructed a study section from the junction with the mainstem to ca. 130-180 m upstream in each tributary (Table 1) and conducted monthly surveys between July and October 2017, as well as an additional December survey in four tributaries (T50, T50.5, KO, and NGN). Water temperature was measured at the midpoint of each section at hourly intervals using data loggers (HOBO 64K Pendant Temperature/Alarm Data Logger or HOBO 13-Foot Fresh Water Level Data Logger; Onset Computer Corp., Bourne, MA, USA). As expected, the two spring-fed tributaries (T50.5 and KO) showed stable water temperatures throughout the season (5-10°C), and the non-spring-fed tributaries, including the multisource tributaries (NGN, T50, T51, and T61), changed between 0°C and more than 15°C (Figure 2).

“Table 1 around here”

In each population census, we caught the southern Asian Dolly Varden and white-spotted charr using a backpack electrofishing unit (LR-20B Electrofisher; Smith-Root, Inc., Vancouver, WA, USA) while walking from the downstream to upstream reaches. Two-pass electrofishing was conducted in each survey. The captured fish were anaesthetized with eugenol (FA100; DS Pharma Animal Health Co., Ltd., Osaka, Japan), the abundance of each species was recorded, and the fork length of each fish was measured to the nearest 1 mm. All fish were released near the capture sites after recovering from anaesthesia. All fish in each tributary and each month were categorized into age 0+ and older fish (> 1+) based on their body size. Age-1+ and older fish were not determined because of the lack of clear size modes. All fish collection was legally conducted in accordance with the permit from the Hokkaido Government. To evaluate stream characteristics at each sampling point, we constructed 10 transects and measured the wetted width. Second, we constructed 5 transects and measured the current velocity at 0.6 × depth at 5 points along the transect with a propeller-based flow metre (model CR-11; Cosmo-riken, Tokyo).

2.2 Statistical analysis

We estimated the population abundance separately for each age class in each month at each tributary for each species using the Carle–Strub method [24], which is the maximum likelihood population estimate and is commonly used to extrapolate species abundances from two-pass electrofishing data [25, 26]. Second, we calculated the southern Asian Dolly Varden ratio (abundance of southern Asian Dolly Varden/total abundance of both species) and its 95% confidence intervals using the Agresti-Coull method [27].

Generalized linear mixed models (GLMMs) were used to evaluate the relationship between the seasonal variation in the abundance of southern Asian Dolly Varden and white-spotted charr and the southern Asian Dolly Varden ratio and water temperature variation. In the analysis, the coefficients of variation (CVs) in the abundance of southern Asian Dolly Varden and white-spotted charr and the southern Asian Dolly Varden ratio were used as response variables, and it was assumed to follow a Gamma distribution with a log link function. The data collected in December were not included in this analysis because some tributaries were not surveyed. We also excluded sites where any of the response variables obtained only zero across the season (age 0+ in T61 and age 0+ and 1+ in NGN for the models of CVs in the abundance of southern Asian Dolly Varden and the southern Asian Dolly Varden ratio). The explanatory variable was the water temperature CV, which was calculated from hourly water temperature data from mid-July to late October. The explanatory variable was standardized (mean = 0, SD = 1) before the analysis. Age class was included as a random intercept to account for age class-level effects.

To quantitatively investigate the effect of temperature on the species ratio, we constructed GLMMs with binomial distributions and logit link functions to data for each month. We used the southern Asian Dolly Varden ratio as a response variable. The proportions derived from count-based data are suitable for modelling with binomial regression [28]. Temperature was tested as an explanatory variable, standardized to the average of the seven days, including the survey date and the six consecutive days after the survey date. Age class was included as a random intercept. For each GLMM, the significance of the explanatory variables was evaluated using type II Wald chi-square tests (p < 0.05).

All data analyses were conducted with R v. 4.2.0 [29] using “FSA” v. 0.9.3 [30] for population abundance estimates and “glmmTMB” v. 1.1.3 [31] for GLMMs.

Despite the notable fluctuations in their abundances, the southern Asian Dolly Varden dominated in spring-fed tributaries throughout the seasons for both age classes, whereas white-spotted charr dominated in non-spring-fed tributaries, with consistently higher southern Asian Dolly Varden ratios in the spring-fed tributaries (Figure 3). KO and T50.5 (i.e., spring-fed tributaries) had a notable population trend in that the abundance of age 0+ white-spotted charr markedly increased (i.e. more than four times higher in August than in July in KO and 27 times higher in September than in July in T50.5), despite stable water temperatures and high abundance of southern Asian Dolly Varden, and then both species tended to decline through the winter (Figure 3A). Age-1+ or older white-spotted charr in T50 showed a similar pattern in that abundance significantly increased from July to August and then declined to winter. Population trends in other tributaries and age classes were not clear partly due to lower abundances and corresponding stochasticity. We found no evidence of winter immigration/aggregation in the tributaries examined.

As expected, CVs in the abundance of southern Asian Dolly Varden and the southern Asian Dolly Varden ratio were significantly affected by temperature CV (CV in the abundance of southern Asian Dolly Varden, χ² = 17.4 and p < 0.0001; CV in the southern Asian Dolly Varden ratio, χ² = 21.3 and p < 0.0001) and increased with increasing temperature CV (Figure 4; Table 2). On the other hand, there was no significant effect on the CV of white-spotted charr abundance (Figure 4; Table 2; χ² = 0.5 and p = 0.4668).

In GLMMs for the species ratio, temperature had significant effects in all seasons: July, χ² = 81.5 and p < 0.0001; August, χ² = 136.2 and p < 0.0001; September, χ² = 85.9 and p < 0.0001; October, χ² = 63.4 and p < 0.0001; December, χ² = 20.3 and p < 0.0001. The southern Asian Dolly Varden ratio decreased with increasing temperature in July, August, and September, but the opposite pattern was observed in October and December (Table 3 and Figure 5).

“Tables 2 and 3 around here”

In tributaries with stable water temperatures (i.e., spring-fed tributaries), southern Asian Dolly Varden abundance and the species ratio in two congeneric salmonids were stable throughout the seasons, consistent with our initial hypothesis. In contrast, seasonal variation in white-spotted charr abundance was not explained by water temperature stability. We found no evidence of winter immigration/aggregation in these tributaries, whereas some previous studies reported winter immigration to warmer tributaries [20, 21]. Water temperature had significant positive effects on the proportion of white-spotted charr during summer, consistent with previous studies [8, 13], but had negative effects during late autumn and winter (Figure 3). The change in the trend, however, is an artefact caused by the consistent dominancy of the southern Asian Dolly Varden in spring-fed tributaries throughout the season, in which the water temperature is lower in summer but higher in winter. Overall, water temperature alone did not explain the abundance and species ratio of the two congeneric salmonids, where temperature-dependent competition has been reported [8, 13]. We discuss the importance of taking seasonality into account when understanding the abundance and distribution of potentially competing salmonids, as well as implications for global climate change.

The southern Asian Dolly Varden dominated in spring-fed tributaries throughout the season, and the abundance and ratio of the southern Asian Dolly Varden were stable. This is partly because the southern Asian Dolly Varden is a more cold-adapted species than the white-spotted charr [e.g., 1, 32]. Accordingly, the former may be competitively dominant over the latter in spring-fed tributaries where the temperature is colder in growing seasons (from spring to summer) [8, 13, 33]. However, the seasonal variation in the white-spotted charr abundance was not explained by temperature variation. There are several reasons for the conflicting results. First, the southern Asian Dolly Varden performed “comparatively better” under lower temperatures, but white-spotted charr may always be superior for direct competition [8, 13]. Thus, irrespective of temperature, white-spotted charr might have immigrated to the tributaries when they needed [e.g. for nursery or escape from the flood, 34]. Indeed, in spring-fed tributaries, the abundance of age 0+ white-spotted charr was remarkably higher in August or September than in July, despite stable water temperature and high abundance of southern Asian Dolly Varden. This immigration may provide some benefits to age 0+ white-spotted charr, such as providing shelter from predators and foraging habitat. These results suggested that white-spotted charr may not be negatively affected by competition, in contrast to southern Asian Dolly Varden, supporting the above interpretation. Second, in later summer or autumn, interference competition might have become weaker due to the preparations for breeding or overwintering. In fact, the feed intake and growth rate are greatly reduced from late summer in salmonids [35, 36]; furthermore, aggressive interactions decrease or disappear in winter [37, 38]. Thus, white-spotted charr could have immigrated to the cold tributaries due to the release of competition even though they are subdominant.

While previous studies have demonstrated the winter immigration or aggregation of salmonids in warm tributaries [20, 21], we found no evidence in our tributaries, including spring-fed tributaries; rather, both the numbers of southern Asian Dolly Varden and white-spotted charr decreased in winter. Previous studies have demonstrated winter immigration in masu salmon and rainbow trout, both belonging to the genus Oncorhynchus, whereas the number of sympatric white-spotted charr declined [39]. Thus, species- or genus-specific winter ecology might explain the different outcomes. In winter, anchor ice and reduced water discharge limit the space for wintering habitat [40], and therefore, interspecific competition for refuges could be stronger. In contrast, a previous study also reported winter aggregation in mixed species of salmonids [41], suggesting a lack of strong interspecific competition. Since winter is one of the critical seasons for the survival of salmonids [42], especially during juvenile stages, it is crucial to understand if or how interspecific competition occurs during winter.

Water temperature had significant effects on the proportion of the two congeneric salmonids, but the effects changed according to the seasons. This could indicate the existence of an optimal temperature (i.e., 6-8°C for the southern Asian Dolly Varden), but the narrow temperature range in October and December and the consistently high proportion of the southern Asian Dolly Varden in spring-fed tributaries suggest that the seasonal change in the temperature effects merely reflects the temperature regimes in the two types of tributaries rather than the seasonal reversal of the competitive relationship. These quantitative relationships, however, provide an important implication. The proportion of the two species sharply changed within a narrow temperature range (9-13°C) during summer (July and August) when the temperature was high. Irrespective of the mechanisms (e.g., species-specific habitat preference, temperature-dependent competition), this indicates that temperature fluctuation significantly affects salmonids, especially for the southern Asian Dolly Varden, which are cold-adapted species and competitively inferior [8, 13].

In summary, despite numerous studies on competition among salmonids, seasonal changes in interspecific competition and resultant distribution and abundance have been critically overlooked. Global warming strongly affects cold-water fish such as salmonids, particularly at the southern limit of a species distribution [43–47]. Nakano et al. [32] indicated that the southern Asian Dolly Varden is more vulnerable to global warming than the white-spotted charr using single-species models that do not account for season. However, some studies have noted that species replacement between competing species can occur as global warming progresses [e.g., 48], and thus, considering biotic interactions in the species distribution model is crucial [49–51]. The impact of global warming on the southern Asian Dolly Varden and white-spotted charr may change when considering season and competing species. Therefore, future studies require more realistic models that consider these factors.

ACKNOWLEDGMENTS

We thank the members of the Ecosystem Management Laboratory, who helped to conduct the field survey and provided valuable comments.

FUNDING

This work was funded through the Research Fund for the Ishikari and Tokachi Rivers provided by the Ministry of Land, Infrastructure, Transport, and Tourism of Japan.

DATA AVAILABILITY STATEMENT

The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

CONFLICT OF INTEREST

None declared.

AUTHOR CONTRIBUTIONS

Conceptualisation: T.Y., I.K. Developing methods, conducting the research, data analysis, preparation of figures and tables: T.Y. Data interpretation, writing: T.Y., I.K., F.N.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

All animal handling in the surveys was conducted in accordance with the Act on Welfare and Management of Animals and the regulations for animal experiments of Hokkaido University. No fish were sacrificed, and no surgical procedures were performed in this study. The Hokkaido Government Kamikawa General Subprefectural Bureau provided permission to perform fish collection (no. 731). Ethical approvals are not required at Hokkaido University for research conducted on fish species such as the southern Asian Dolly Varden and white-spotted charr used in this study.

CONSENT FOR PUBLICATION

Not applicable.

Fausch KD, Nakano S, Ishigaki K. Distribution of two congeneric charrs in streams of Hokkaido Island, Japan: considering multiple factors across scales. Oecologia. 1994;100–100:1–12.
Morita K, Sahashi G, Tsuboi J. Altitudinal niche partitioning between white-spotted charr (Salvelinus leucomaenis) and masu salmon (Oncorhynchus masou) in a Japanese river. Hydrobiologia. 2016;783:93–103.
Tsuboi JI, Iwata T, Morita K, Endou S, Oohama H, Kaji K. Strategies for the conservation and management of isolated salmonid populations: lessons from Japanese streams. Freshw Biol. 2013;58:908–17.
Weigel DE, Sorensen PW. The Influence of Habitat Characteristics on the Longitudinal Distribution of Brook, Brown, and Rainbow Trout in a Small Midwestern Stream. J Freshw Ecol. 2001;16:599–613.
Yamamoto S, Kitano S, Sakano H, Yagyu M. Differences in longitudinal distribution patterns along a Honshu stream of brown trout Salmo trutta, white-spotted charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou. Fish Sci. 2010;76:275–80.
Koizumi I, Maekawa K. Metapopulation structure of stream-dwelling Dolly Varden charr inferred from patterns of occurrence in the Sorachi River basin, Hokkaido, Japan. Freshw Biol. 2004;49:973–81.
Hasegawa K, Maekawa K. Different longitudinal distribution patterns of native white-spotted charr and non-native brown trout in Monbetsu stream, Hokkaido, northern Japan. Ecol Freshw Fish. 2008;17:189–92.
Taniguchi Y, Nakano S. Condition-specific competition: Implications for the altitudinal distribution of stream fishes. Ecology. 2000;81:2027–39.
Mee JA, Robins GL, Post JR. Patterns of fish species distributions replicated across three parallel rivers suggest biotic zonation in response to a longitudinal temperature gradient. Ecol Freshw Fish. 2018;27:44–61.
Taniguchi Y, Rahel FJ, Novinger DC, Gerow KG. Temperature mediation of competitive interactions among three fish species that replace each other along longitudinal stream gradients. Can J Fish Aquat Sci. 1998;55:1894–901.
McHugh P, Budy P. An experimental evaluation of competitive and thermal effects on brown trout (Salmo trutta) and Bonneville cutthroat trout (Oncorhynchus clarkii utah) performance along an altitudinal gradient. Can J Fish Aquat Sci. 2005;62:2784–95.
Takami T, Kitano F, Nakano S. High Water Temperature Influences on Foraging Responses and Thermal Deaths of Dolly Varden Salvelinus malma and White-spotted Charr S. leucomaenis in a Laboratory. Fish Sci. 1997;63:6–8.
Watz J, Otsuki Y, Nagatsuka K, Hasegawa K, Koizumi I. Temperature‐dependent competition between juvenile salmonids in small streams. Freshw Biol. 2019;64:1534–41.
Al-Chokhachy R, Lien M, Shepard BB, High B. The interactive effects of stream temperature, stream size, and non-native species on Yellowstone cutthroat trout. Can J Fish Aquat Sci. 2021;78:1073–83.
Sharma A, Dubey VK, Johnson JA, Rawal YK, Sivakumar K. Is there always space at the top? Ensemble modeling reveals climate-driven high-altitude squeeze for the vulnerable snow trout Schizothorax richardsonii in Himalaya. Ecol Indic. 2021;120:106900.
Comte L, Grenouillet G. Do stream fish track climate change? Assessing distribution shifts in recent decades. Ecography (Cop). 2013;36:1236–46.
Comte L, Buisson L, Daufresne M, Grenouillet G. Climate-induced changes in the distribution of freshwater fish: observed and predicted trends. Freshw Biol. 2013;58:625–39.
Sakai M, Iwabuchi K, Bauman D. Unique habitat and macroinvertebrate assemblage structures in spring-fed stream: a comparison among clastic lowland tributaries and mainstreams in northern Japan. Community Ecol. 2021;22:193–202.
Lusardi RA, Bogan MT, Moyle PB, Dahlgren RA. Environment shapes invertebrate assemblage structure differences between volcanic spring-fed and runoff rivers in northern California. Freshw Sci. 2016;35:1010–22.
Morita K, Morita SH, Nagasawa T. Seasonal changes in stream salmonid population densities in two tributaries of a boreal river in northern Japan. Ichthyol Res. 2011;58:134–42.
Koizumi I, Kanazawa Y, Yamazaki C, Tanaka Y, Takaya K. Extreme winter aggregation of invasive rainbow trout in small tributaries: implications for effective control. Ichthyol Res. 2017;64:197–203.
Koizumi I, Maekawa K. Spawning Migration of Stream-Dwelling Dolly Varden in Spring-Fed Tributaries of the Shiisorapuchi River, Japan. J Freshw Ecol. 2003;18:321–31.
Koizumi I, Shimatani IK. Socially induced reproductive synchrony in a salmonid: an approximate Bayesian computation approach. Behav Ecol. 2016;27:1386–96.
Carle FL, Strub MR. A New Method for Estimating Population Size from Removal Data. Biometrics. 1978;34:621–30.
Kanno Y, Yui N, Mamiya W, Sakai R, Yabuhara Y, Miyazaki T, et al. A multistate mark–recapture approach to characterize stream fish movement at multiple spatial scales. Can J Fish Aquat Sci. 2020;77:1090–100.
Bergerot B, Bret V, Cattanéo F. Similarity in seasonal flow regimes, not regional environmental classifications explain synchrony in brown trout population dynamics in France. Freshw Biol. 2019;64:1226–38.
Agresti A, Coull BA. Approximate is Better than “Exact” for Interval Estimation of Binomial Proportions. Am Stat. 1998;52:119–26.
Douma JC, Weedon JT. Analysing continuous proportions in ecology and evolution: A practical introduction to beta and Dirichlet regression. Methods Ecol Evol. 2019;10:1412–30.
R Core Team. R: A Language and Environment for Statistical Computing. 2022.
Ogle DH, Doll JC, Wheeler P, Dinno A. FSA: Fisheries Stock Analysis. 2022.
Brooks ME, Kristensen K, van Benthem KJ, Magnusson A, Berg CW, Nielsen A, et al. glmmTMB Balances Speed and Flexibility Among Packages for Zero-inflated Generalized Linear Mixed Modeling. R J. 2017;9:378–400.
Nakano S, Kitano F, Maekawa K. Potential fragmentation and loss of thermal habitats for charrs in the Japanese archipelago due to climatic warming. Freshw Biol. 1996;36:711–22.
Yamada T, Koizumi I, Urabe H, Nakamura F. Temperature-Dependent Swimming Performance Differs by Species: Implications for Condition-Specific Competition between Stream Salmonids. Zoolog Sci. 2020;37:1–5.
Koizumi I, Kanazawa Y, Tanaka Y. The Fishermen Were Right: Experimental Evidence for Tributary Refuge Hypothesis During Floods. Zoolog Sci. 2013;30:375–9.
Tveiten H, Johnsen HK, Jobling M. Influence of maturity status on the annual cycles of feeding and growth in Arctic charr reared at constant temperature. J Fish Biol. 1996;48:910–24.
Saether B-S, Johnsen HK, Jobling M. Seasonal changes in food consumption and growth of Arctic charr exposed to either simulated natural or a 12:12 LD photoperiod at constant water temperature. J Fish Biol. 1996;48:1113–22.
Whalen KG, Parrish DL. Nocturnal habitat use of Atlantic salmon parr in winter. Can J Fish Aquat Sci. 1999;56:1543–50.
Vehanen T, Huusko A. Behaviour and habitat use of young-of-the-year Atlantic salmon (Salmo salar) at the onset of winter in artificial streams. Arch für Hydrobiol. 2002;154:133–50.
Sahashi G, Morita K. Fall–winter collection of two salmonid species: seasonal changes in population densities in four tributaries of the Kushiro river system. Ichthyol Res. 2014;61:189–92.
Huusko A, Greenberg L, Stickler M, Linnansaari T, Nykänen M, Vehanen T, et al. Life in the ice lane: the winter ecology of stream salmonids. River Res Appl. 2007;23:469–91.
Cunjak RA, Power G. Winter Habitat Utilization by Stream Resident Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta). Can J Fish Aquat Sci. 1986;43:1970–81.
Mitro MG, Zale A V. Seasonal Survival, Movement, and Habitat Use of Age-0 Rainbow Trout in the Henrys Fork of the Snake River, Idaho. Trans Am Fish Soc. 2002;131:271–86.
Almodóvar A, Nicola GG, Ayllón D, Elvira B. Global warming threatens the persistence of Mediterranean brown trout. Glob Chang Biol. 2012;18:1549–60.
Jonsson B, Jonsson N. A review of the likely effects of climate change on anadromous Atlantic salmon Salmo salar and brown trout Salmo trutta, with particular reference to water temperature and flow. J Fish Biol. 2009;75:2381–447.
Keleher CJ, Rahel FJ. Thermal Limits to Salmonid Distributions in the Rocky Mountain Region and Potential Habitat Loss Due to Global Warming: A Geographic Information System (GIS) Approach. Trans Am Fish Soc. 1996;125:1–13.
Meisner JD. Potential Loss of Thermal Habitat for Brook Trout, Due to Climatic Warming, in Two Southern Ontario Streams. Trans Am Fish Soc. 1990;119:282–91.
Winfield IJ, Hateley J, Fletcher JM, James JB, Bean CW, Clabburn P. Population trends of Arctic charr (Salvelinus alpinus) in the UK: assessing the evidence for a widespread decline in response to climate change. Hydrobiologia. 2010;650:55–65.
Urban MC, Tewksbury JJ, Sheldon KS. On a collision course: competition and dispersal differences create no-analogue communities and cause extinctions during climate change. Proc R Soc B Biol Sci. 2012;279:2072–80.
Anderson RP. When and how should biotic interactions be considered in models of species niches and distributions? J Biogeogr. 2017;44:8–17.
Wenger SJ, Isaak DJ, Luce CH, Neville HM, Fausch KD, Dunham JB, et al. Flow regime, temperature, and biotic interactions drive differential declines of trout species under climate change. Proc Natl Acad Sci. 2011;108:14175–80.
Wisz MS, Pottier J, Kissling WD, Pellissier L, Lenoir J, Damgaard CF, et al. The role of biotic interactions in shaping distributions and realised assemblages of species: implications for species distribution modelling. Biol Rev. 2013;88:15–30.

Table 1. Physical characteristics of the six studied streams and environmental conditions in the study sections.

Metric	T50	T50.5	T51	KO	T61	NGN
Tributary type	Non-spring	Spring	Non-spring	Spring	Non-spring	Non-spring
Length of study section (m)	168.0	150.7	179.2	169.3	132.1	170.7
Average stream wetted width (m)	1.76	1.21	1.61	1.16	0.87	3.26
Average current velocity (m/s)	0.17	0.22	0.25	0.28	0.28	0.88

Table 2. Results of GLMMs testing the effects of water temperature CV on CVs of the abundance of southern Asian Dolly Varden and white-spotted charr and the southern Asian Dolly Varden ratio.

Fixed effect		Estimate	SE	p
SADV abundance CV
	Intercept	-0.632	0.173	0.0003
	Temperature CV	0.849	0.203	< 0.0001
WSC abundance CV
	Intercept	-0.287	0.140	0.0395
	Temperature CV	-0.096	0.132	0.4668
SADV ratio CV
	Intercept	-0.888	0.285	0.0019
	Temperature CV	1.122	0.243	< 0.0001

SADV, southern Asian Dolly Varden; WSC, white-spotted charr.

Table 3. Results of GLMMs testing the effects of water temperature on the southern Asian Dolly Varden ratio in each month.

Fixed effect		Estimate	SE	p
July
	Intercept	-0.785	0.581	0.1770
	Temp	-2.785	0.309	< 0.0001
August
	Intercept	-2.058	0.230	< 0.0001
	Temp	-3.358	0.288	< 0.0001
September
	Intercept	-0.991	0.159	< 0.0001
	Temp	-1.639	0.177	< 0.0001
October
	Intercept	-1.817	0.484	0.0002
	Temp	2.715	0.341	< 0.0001
December
	Intercept	-0.762	0.345	0.0272
	Temp	2.054	0.455	< 0.0001

No competing interests reported.

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Seasonal changes in the ratio of congeneric charrs in northern Japanese tributaries with different temperature regimes

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