Breathing space: deoxygenation of aquatic environments can drive differential ecological impacts across biological invasion stages

Abstract

The influence of climate change on the ecological impacts of invasive alien species (IAS) remains understudied, with deoxygenation of aquatic environments often-overlooked as a consequence of climate change. Here, we therefore assessed how oxygen saturation affects the ecological impact of a predatory invasive fish, the Ponto-Caspian round goby (Neogobius melanostomus), relative to a co-occurring endangered European native analogue, the bullhead (Cottus gobio) experiencing decline in the presence of the IAS. In individual trials and mesocosms, we assessed the effect of high, medium and low (90%, 60% and 30%) oxygen saturation on: (1) functional responses (FRs) of the IAS and native, i.e. per capita feeding rates; (2) the impact on prey populations exerted; and (3) how combined impacts of both fishes change over invasion stages (Pre-invasion, Arrival, Replacement, Proliferation). Both species showed Type II potentially destabilising FRs, but at low oxygen saturation, the invader had a significantly higher feeding rate than the native. Relative Impact Potential, combining fish per capita effects and population abundances, revealed that low oxygen saturation exacerbates the high relative impact of the invader. The Relative Total Impact Potential (RTIP), modelling both consumer species’ impacts on prey populations in a system, was consistently higher at low oxygen saturation and especially high during invader Proliferation. In the mesocosm experiment, low oxygen lowered RTIP where both species were present, but again the IAS retained high relative impact during Replacement and Proliferation stages at low oxygen. We also found evidence of multiple predator effects, principally antagonism. We highlight the threat posed to native communities by IAS alongside climate-related stressors, but note that solutions may be available to remedy hypoxia and potentially mitigate impacts across invasion stages.

Abiotic and biotic correlates of the occurrence, extent and cover of invasive aquatic Elodea nuttallii

“…The vast volumes of weed occurring in the lake will, cyclically, die and decay, a process which utilises oxygen (Asaeda et al, 2001; Jewell, 1971; Pereira et al, 1994). Concerningly, the lowering of dissolved oxygen can impact other aquatic life and potentially affect the species composition, having significant knock‐on effects on the biological functioning of shallow, freshwater systems (Buscemi, 1958; Dickey et al, 2021).…”

Predicting ecological impacts of the invasive brush-clawed shore crab under environmental change

“…Importantly, the experimental tanks used here were constantly aerated to avoid oxygen limitation, especially at the higher temperature level. This prevented the interacting effects of the decreased capacity of the warmed water to hold dissolved oxygen and concordant physiological insufficiency of the animal’s oxygen uptake 62 , 63 .…”

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

“…In addition, experimentally-derived estimates of invasive species' per capita effects relative to those of native analogues are useful tools to forecast the former's potential ecological impact (Dick et al 2014). Invasive species often demonstrate higher and more efficient resource utilisation relative to ecologically similar native species across taxonomic groups (Dick et al 2014;Crookes et al 2019;Dickey et al 2021). Taking such per capita impact prediction one step further, the Functional Response Ratio (FRR) is derived from the FR's constituent parameters (attack rate divided by handling time).…”