Although the species has yet to beconfirmed in the southern part of the Bay of Biscay as well as in northernBrittany, in situ surveys and observations should be maintained to monitorpotential sprea

Mnemiopsis leidyi populations can exertsignificant grazing pressure on veliger stocks by ingesting up to 95% of thebivalve larval stock per day

it is likely that M. leidyi will reach the Adour, Nivelle and Bidassoaestuaries in the near future and then extend to the northern coast of Spain.

ince then, its presence has beenrecurrent every year, and its range in the estuary has expanded

iNaturalist 2022

such as photographs takenduring scuba diving sessions or observations from zooplankton samplings.

The Bay of Biscay is the leading French region for bivalve exploitation,mainly the Pacific oyster Magallana gigas (Thunberg, 1793) and the bluemussel Mytilus edulis Linnaeus 1758, accounting for approximately 1400shellfish farming companies

A second introduction in Europe probably took place in the WaddenSea in the early 2000s

This study aims to assess its expansion along the French Atlantic coast, mainlyin the Bay of Biscay and Iroise Sea

along 500 km of coastlin

colonise the Spanish Gulf coast in the near future through naturaldispersal via currents

s M. leidyi consumes bivalve larvae, thepotential economic and ecological impacts on this shellfish industry are discussed

The species has spread from the Black Sea to both the eastern andwestern basins of the Mediterranean Sea and Adriatic Sea

The extremely divergent chemical and biological differences observed between low- and high- density H. amphibius pools during the dry season were almost completely erased during the wet season when the river resumed flow

This lack of numerical difference was largely driven by the increase in coleopterans, which dominated high-density H. amphibius pools.

current anthropogenic water abstraction has greatly exacerbated seasonal river dry-down to the point that the river is unable to maintain dry-season flow. Thus, this anthropogenically driven alteration to river hydrology is influencing the ecological impact of H. amphibius subsidies.

To empirically address these questions, we used a unique field context where, as a result of human modification, a historically perennial river in central Tanzania

The resultant unnaturally high variation in seasonal river flow will likely be further exacerbated by global climate change

H. amphibius deliver substantial, and continuous, supplies of terrestrially derived organic matter and nutrients, such as nitrogen and phosphorus, to aquatic ecosystems

Semiaquatic species that rely on terrestrial sources of energy and nutrients (7, 8) can have large impacts on recipient aquatic habitats, affecting nutrient cycling, food web dynamics, and aquatic community structure

Widespread human-driven shifts in hydrology appear to redefine the role of H. amphibius, altering their influence on ecosystem diversity and functioning in a fashion that may be more severe than presently appreciated.