The effect of temperature on fish swimming and schooling is context dependent

Abstract

Temperature is highly influential on the physiology and behaviour of ectotherms. In fish, temperature affects social interactions such as schooling behaviour, a common defence against predation. However, the effect of temperature on the ability of schooling fish to collectively respond to a predator is unknown. Here we used a loom stimulus to simulate an approaching predator that elicited a fleeing response in schooling fish over a range of water temperatures (9-29°C) and group sizes (1-16 fish). While speed and acceleration always exhibited a positive curvilinear response to temperature, the optimal temperature at which performance peaked was different during the predation threat versus when they were unperturbed. Similarly, group-level metrics were sensitive to temperature immediately after a loom stimulus but showed no response to temperature during unperturbed swimming. The time taken for fish to respond to the loom stimulus was minimal at 20°C. The proportion of fish that startled, during a loom, peaked at 13°C -around the same temperature at which speed, and acceleration was maximum. Taken together, our results suggest that ectothermic fish may be able to compensate for their slower swim speeds at lower temperatures during unperturbed swimming by increasing their sensitivity to startle in response to a predation threat. More generally, we show that in ectotherms the qualitative and quantitative effect of temperature on a behavioural trait may be dependent on the context.

Increased water temperature and turbidity act independently to alter social behavior in guppies (Poecilia reticulata)

“…Previous work has also found that fish form tighter shoals at higher temperatures (Krause & Godin, 1995;Kuruvilla et al, 2022;Pitcher & Parrish, 1993;Pritchard et al, 2001;Weetman et al, 1998Weetman et al, , 1999.…”

“…We observed an increase in shoaling at the higher temperature as measured by the local‐scale NND and one of the global scale measures (the index of dispersion), although no effect on the other global measure of cohesion, the mean inter‐individual distance, was found. Previous work has also found that fish form tighter shoals at higher temperatures (Krause & Godin, 1995 ; Kuruvilla et al, 2022 ; Pitcher & Parrish, 1993 ; Pritchard et al, 2001 ; Weetman et al, 1998 , 1999 ). This may be a response to increased risk perception, as higher temperatures also increase predators' metabolic requirements and speed (Domenici et al, 2019 ; Ohlberger et al, 2012 ), although this is not supported by our experiment as here the measure of risk perception used (refuge use) was reduced at higher temperatures, suggesting that the fish were bolder.…”

“…Anthropogenic activities such as urbanization and agriculture can cause shifts in water flow, water temperature, eutrophication, turbidity, and levels of pollution within the aquatic environment (Barnett et al, 2008 ; Landrigan et al, 2018 ; Vörösmarty et al, 2013 ). However, while some studies have explored the ecological and physical effects of co‐occurring multiple stressors (Darling & Côté, 2008 ; Orr et al, 2020 ) and others have tested how collective behavior changes with single stressors (Bartolini et al, 2015 ; Herbert‐Read et al, 2017 ), far fewer studies have explored how social behavior is impacted by multiple stressors (Fisher et al, 2021 ; Ginnaw et al, 2020 ; Kuruvilla et al, 2022 ).…”

“…With heightened activity and energy levels in warmer water (Biro et al, 2010 ; Holt & Jørgensen, 2015 ; Weetman et al, 1998 ), fish may be able to shoal more effectively due to improved swimming abilities. Predatory fish can exhibit higher attack rates with increased water temperature (Krause & Godin, 1995 ; Persson, 1986 ; Sylvester, 1972 ), thus elevated antipredator behaviors such as shoaling in warmer water may be adaptive and a result of physiological changes (Kuruvilla et al, 2022 ). However, climate change can have variable effects on different species, and the increasing temperature has been linked to a decrease in shoaling in some species (Bartolini et al, 2015 ; Colchen et al, 2016 ).…”

Temperature and turbidity interact synergistically to alter anti-predator behaviour in the Trinidadian guppy

“…In fish, beside mechanistic changes in motility, temperature fluctuations can have positive or negative effects on antipredator behaviour depending on a variety of factors, such as predator presence (Weetman et al, 1999), life stage (Colchen et al, 2016), mixed-species shoals (Mitchell et al, 2022;Paijmans et al, 2020) or activity levels of potential shoal mates (Pritchard et al, 2001). This suggests that the effects of increased temperature on behavioural traits are context dependant (Kuruvilla et al, 2022).…”