Effects of temperature on the behaviour and metabolism of an intertidal foraminifera and consequences for benthic ecosystem functioning

Abstract

Heatwaves have increased in intensity, duration and frequency over the last decades due to climate change. Intertidal species, living in a highly variable environment, are likely to be exposed to such heatwaves since they can be emerged for more than 6 h during a tidal cycle. Little is known, however, on how temperature affects species traits (e.g. locomotion and behaviour) of slow-moving organisms such as benthic foraminifera (single-celled protists), which abound in marine sediments. Here, we examine how temperature influences motion-behaviour and metabolic traits of the dominant temperate foraminifera Haynesina germanica by exposing individuals to usual (6, 12, 18, 24, 30 °C) and extreme (high; i.e. 32, 34, 36 °C) temperature regimes. Our results show that individuals reduced their activity by up to 80% under high temperature regimes whereas they remained active under the temperatures they usually experience in the field. When exposed to a hyper-thermic stress (i.e. 36 °C), all individuals remained burrowed and the photosynthetic activity of their sequestered chloroplasts significantly decreased. Recovery experiments subsequently revealed that individuals initially exposed to a high thermal regime partially recovered when the hyper-thermic stress ceased. H. germanica contribution to surface sediment reworking substantially diminished from 10 mm3 indiv−1 day−1 (usual temperature) to 0 mm3 indiv−1 day−1 when individuals were exposed to high temperature regimes (i.e. above 32 °C). Given their role in sediment reworking and organic matter remineralisation, our results suggest that heatwaves may have profound long-lasting effects on the functioning of intertidal muddy ecosystems and some key biogeochemical cycles.

Intertidal zonation of live benthic foraminiferal assemblages from mangrove environments around south-west Penang Island, Peninsular Malaysia

“…Several studies have reported that increasing pore water temperatures can cause adverse effects to intertidal foraminifera (i.e. reduce locomotion, metabolism and reproduction (Buzas & Severin, 1993; Gross, 2000; Wukovits et al ., 2017; Li et al ., 2019; Deldicq et al ., 2021). On a regional scale, cooler water temperatures are known to favour the preservation of agglutinated tests compared with warmer regions and tropical environments such as mangroves (Goldstein & Watkins, 1999; Debenay et al ., 2002; Berkeley et al ., 2009 a ).…”

Inter-specific and inter-individual trait variability matter in surface sediment reworking rates of intertidal benthic foraminifera

“…During the sampling period, temperature has increased from ~7°C (February) to ~18°C (June), which may have induced a seasonal effect on the organism' activity as evidenced for macrofaunal species (Pascal et al 2019). A recent study on Haynesina germanica showed however, that foraminiferal SSRRi has a low thermal dependence in the range 6-24°C (Deldicq et al 2021). In this study, we assume that the potential seasonal effect could be negligible through the use of an acclimation period carried out before running the experiment.…”

Sports Metabolism in Improving National Fitness

“…Low-volume training requires subjects to train for 2 to 3 hours a day. 3 In this study, the second training day of the two training weeks was selected as the study content, and the following day after training was used as the recovery period.…”