Combined, short-term exposure to reduced seawater pH and elevated temperature induces community shifts in an intertidal meiobenthic assemblage

Future ocean climate homogenizes communities across habitats through diversity loss and rise of generalist species

“…The overall decrease in metacommunity species richness under ocean warming and acidification combined also caused a decrease in nematode trophic diversity, which was mainly related to the loss of predatory nematodes. In addition, copepod density decreased under the combined effects of warming and OA, as previously observed (Mevenkamp, Ong, Van Colen, Vanreusel, & Guilini, ; Sarmento, Parreira Santos, Hale, Ingels, & Widdicombe, ). These changes may lead to a loss in ecosystem function since copepods and predatory nematodes create important trophic links between meiofauna and larger animals such as macrofaunal invertebrates and demersal fishes (Gingold, Moens, & Rocha‐Olivares, ; Zeppilli et al, ).…”

Ocean acidification alters meiobenthic assemblage composition and organic matter degradation rates in seagrass sediments

“…Previous studies have already shown that OA can shift meiobenthic community composition, as a result of differential sensitivity of the different taxa (Hale et al ; Schade et al ; Mevenkamp et al ). In accordance with the literature, nematodes, the dominant meiobenthic taxon at our study site, were unaffected by low pH.…”

“…Negative effects on nematode survivorship have been documented only at extremely low pH levels (~ ≤ 6). However, a recent study using a staining technique found an increase in nematode mortality under OA, whereas nematode density was unaffected, likely due to a reduced degradation rate of dead nematode bodies at low pH (Mevenkamp et al ). These results stress the importance of assessing nematode mortality in OA studies, as stable or even increased densities of these animals could be an artifact of reduced body decomposition, potentially hiding more severe impacts of OA on this dominant group.…”

“…This abundant and high diverse group of small invertebrates (< 1 mm) plays key ecological roles in marine sediments, contributing to energy transfer to higher trophic levels (Schratzberger and Ingels ) and increasing OM remineralization, through the stimulation of microbial activities (Nascimento et al ; Bonaglia et al ; Lacoste et al ). OA can change meiobenthic assemblages either directly, by altering metabolic processes, or indirectly, by modifying interactions among species and trophic groups (e.g., predation pressure; Kurihara et al ; Dashfield et al ; Widdicombe and Spicer ; Kroeker et al ; Meadows et al ; Mevenkamp et al ). Laboratory (generally short‐term) studies have reported divergent responses to OA of different meiobenthic taxa, with the dominant one (typically nematodes and copepods) generally remaining unaffected or even increasing in abundance, whereas others, such as copepod naupli, gastrotrichs, and foraminifera, showing opposing trends (Haynert et al ; Meadows et al ; Lee et al ; Mevenkamp et al ).…”

“…OA can change meiobenthic assemblages either directly, by altering metabolic processes, or indirectly, by modifying interactions among species and trophic groups (e.g., predation pressure; Kurihara et al ; Dashfield et al ; Widdicombe and Spicer ; Kroeker et al ; Meadows et al ; Mevenkamp et al ). Laboratory (generally short‐term) studies have reported divergent responses to OA of different meiobenthic taxa, with the dominant one (typically nematodes and copepods) generally remaining unaffected or even increasing in abundance, whereas others, such as copepod naupli, gastrotrichs, and foraminifera, showing opposing trends (Haynert et al ; Meadows et al ; Lee et al ; Mevenkamp et al ). In contrast, long‐term exposure to low pH condition at submarine CO 2 vents led to a severe decline in meiofaunal density, suggesting limited capacities for several taxa to withstand or adapt to OA (Molari et al ).…”