Water-seeking behavior among terrestrial arthropods and mollusks in a cool mesic region: Spatial and temporal patterns

Abstract

Dehydration can have negative effects on animal physiological performance, growth, reproduction, and survival, and most animals seek to minimize these effects by reducing water losses or seeking water sources. Much—but not all—of the research on animal water balance comes from dryland ecosystems. However, animals inhabiting mesic regions may also experience desiccating conditions, for example within urban heat islands or during heatwaves and droughts. Here we examined how spatial variation in impervious surface and spatial and temporal variation in microclimate impact water demand behavior of terrestrial arthropods and mollusks in three areas of mesic Northwest Ohio, with analysis of taxa that exhibited the greatest water demand behavior. Water demand behavior was measured as the frequency that individuals were observed at an artificial water source (a moistened pouch), relative to the frequency at a control (a dry pouch). Overall, terrestrial arthropods and mollusks were found about twice as often at the water source than at the control (equivalent to 86 more observations on the wet pouch than on dry at each site, on average), with ants accounting for over 50% of the overall response in urban areas. Daily fluctuations in vapor pressure deficit (VPD) best predicted daily variation in water demand behavior, with increased demand at higher VPD. Mean VPD was generally highest near urbanized areas, but effects of VPD on water demand behavior were generally lower in urbanized areas (possibly related to reductions in overall abundance reducing the potential response). On certain days, VPD was high in natural areas and greenspaces, and this coincided with the highest arthropod water demand behavior observed. Our results suggest that terrestrial arthropod communities do experience periods of water demand within mesic regions, including in greenspaces outside cities, where they appear to respond strongly to short periods of dry conditions—an observation with potential relevance for understanding the effects of climate change.

Wet and dry extremes reduce arthropod biomass independently of leaf phenology in the wet tropics

“…Several studies have found reduced activity of rainforest ants, beetles and termites during heavy rain (Basu, 1997 ; Dibog et al, 1998 ; Farji‐Brener et al, 2018 ; Grimbacher & Stork, 2009 ) and in Panamanian rainforest, aerial insects shifted activity from canopy gaps during the wet season to forest understory during the dry season (Richards & Windsor, 2007 ). High VPD can influence behavior (Becker et al, 2021 ), and in arid systems arthropods often seek moist refugia and enter dormancy (Denlinger, 1986 ). We found effects of rainfall were weaker for sampling methods with clear changes in activity such as greater numbers of aerial and leaf‐litter taxa during sunny, warm periods.…”

Dehydration Dynamics in Terrestrial Arthropods: From Water Sensing to Trophic Interactions

“…Insects and other arthropods employ a variety of behavioral approaches to avoid or cope with dehydration, and these activities have profound impacts on trophic interactions. Under desiccating conditions, arthropods may either seek out additional water sources (e.g., 6,45,92,140) or seek refugia that lower water loss rates (32,89). When terrestrial arthropods seek water sources, in some cases, the only available water is within food, resulting in increases in consumption of vegetation by herbivores or prey by predators (89).…”

Histological Studies of Snails at Different Periods of Their Life Activity

“…Terrestrial mollusks are an ecological group of creatures that makes up about 35,000 modern species. They belong to the Gastropoda class and are an important part of many ecosystems as they process much of the dead organic matter, distributing some substances and forming the diet basis for many animals (Köse et al, 2015;Peña et al, 2017;Cilia & Fratini, 2018;Becker et al, 2021).…”