A summer heat wave decreases the immunocompetence of the mesograzer, Idotea baltica

Abstract

Extreme events associated with global change will impose increasing stress on coastal organisms. How strong biological interactions such as the host-parasite arms-race are modulated by environmental change is largely unknown. The immune system of invertebrates, in particular phagocytosis and phenoloxidase activity response are key defence mechanisms against parasites, yet they may be sensitive to environmental perturbations. We here simulated an extreme event that mimicked the European heat wave in 2003 to investigate the eVect of environmental change on the immunocompetence of the mesograzer Idotea baltica. Unlike earlier studies, our experiment aimed at simulation of the natural situation as closely as possible by using long acclimation, a slow increase in temperature and a natural community setting including the animals' providence with natural food sources (Zostera marina and Fucus vesiculosus). Our results demonstrate that a simulated heat wave results in decreased immunocompetence of the mesograzer Idotea baltica, in particular a drop of phagocytosis by 50%. This suggests that global change has the potential to signiWcantly aVect host-parasite interactions.

Combined effects of larval exposure to a heat wave and chlorpyrifos in northern and southern populations of the damselfly Ischnura elegans

“…An increased PO activity in response to a heat wave has also been reported in crickets (Adamo and Lovett, 2011) and may be adaptive as some pathogens may develop faster at higher temperatures (Karnoven et al, 2010). Yet, also strong decreases in immune function after a 1-week heat wave treatment have been reported in a freshwater snail exposed to 30°C (Seppälä and Jokela, 2011) and in a marine crustacean exposed to 26°C (Roth et al, 2010). This illustrates that heat waves may have strongly opposing fitness effects on different species and therefore have the potential to generate changes in community composition.…”

Heat and immunity: an experimental heat wave alters immune functions in three‐spined sticklebacks (Gasterosteus aculeatus)

“…If pathogens survive (evade) the attack by innate immunity, acquired immunity is activated to produce highly specific antibodies to facilitate elimination of the invaders. However, ectothermic animals are generally adapted to a certain temperature range, and temperature extremes will cause stress, which may lead to decreased immune functions (Cheng et al 2003;Dove et al 2005;Roth, Kurtz & Reusch 2010;Seppaelae & Jokela 2011).…”

Resilience of an isopod population (Cyathura carinata) to multiple stress factors in a temperate estuarine system

“…Temperature was regarded as a crucial factor controlling both the process of sex reversal and reproduction (Jazdzewski, 1969). Roth et al (2010) proved that temperature extremes were associated with metabolic stress and reduced immunocompetence of the isopod Idotea baltica; accordingly, the response of C. carinata may be similar. Together with the hypothesis of reduced survival of these individuals, it is also possible that cyathurans facing adverse conditions migrate to locations where the conditions are more favourable (Burbanck & Burbanck, 1967), for example the subtidal environment.…”

“…Moreover, they are susceptible to the climate variability that is one of the greatest environmental, social, and economic threats menacing the planet nowadays (Harley et al, 2006). Erratic weather patterns, for example precipitation unpredictability (with increased risks of floods and droughts) and temperature variability (reflected on the increasing number of episodic heat waves), are becoming more frequent (IPCC, 2007;Roth et al, 2010). The scale and array of climatic alterations in the physical environment may induce substantial responses in the biota (Harley et al, 2006).…”