Towards a mechanistic understanding of individual‐level functional responses: Invasive crayfish as model organisms

Abstract

In novel communities, a rising number of new and emerging invasive species interact with resident species, some of which are non‐native themselves. We implemented an innovative trophic interaction framework for novel communities and quantified the interaction strength and impact potential of a truly novel species (marbled crayfish Procambarus virginalis) with a resident non‐native counterpart (spiny‐cheek crayfish Faxonius limosus). As prey, we used Dreissena mussels, which are non‐native as well and now hold a key position in many European and North American aquatic ecosystems. For both crayfish species, we predicted functional responses based on a mechanistic model that we parameterised with a set of experimental observations of foraging behaviour and satiation. We compared these predicted functional responses to empirically observed responses. In addition, we incorporated behavioural traits such as aggression, activity, and boldness in the comparisons between the species and individuals to determine their influence on functional responses. We tested individuals from aquarium stocks as well as naturalised individuals from invaded water bodies. Altogether, we performed 1,095 experiments with 26 individual crayfish. We found that per capita predation of spiny‐cheek crayfish exceeded that of marbled crayfish from aquaria and naturalised individuals. Functional responses differed between species and were mostly higher for spiny‐cheek crayfish males. Marbled crayfish, however, were more voracious and reached satiation more slowly. Consumption rates correlated with aggression for marbled crayfish and with an aggressive threat response for spiny‐cheek crayfish. We conclude that spiny‐cheek crayfish can reach higher short‐term consumption rates than marbled crayfish, but both species probably do not substantially affect Dreissena mussel populations in the field. For marbled crayfish, high long‐term consumption, interspecific aggression, and reproduction rates can promote their establishment and spread. Risk assessments of these invaders should be improved by considering numerical responses, and different prey organisms and predators.

Pilferer, murderer of innocents or prey? The potential impact of killer shrimp (Dikerogammarus villosus) on crayfish

“…In addition, they may have a higher metabolic rate at 20 °C as warm water species compared to cold water signal crayfish. Marbled crayfish have also been found to be more voracious and slower to reach satiation than spinycheek crayfish (Linzmaier and Jeschke 2019).…”

KAPASITAS POTENSI PARASITISME Trichogramma sp. (Hymenoptera: Trichogrammatidae) TERHADAP Corcyra sp.

“…Tingkat waktu pemangsaan dan penanganan mangsa (Singh, 2022) sering dilakukan oleh predator sebelum terjadinya predasi. Hal ini dilakukan agar predator dapat memanfaatkan waktu dengan baik (Dong et al, 2017;Urban et al, 2020), metabolisme (Valderrama & Fields, 2016;Cuthbert et al 2018;Stefan & Jonathan, 2019), suhu (Kristina et al, 2018;Daugaard et al 2019), dan penyesuaian habitat (Canavero et al, 2017).…”

“…Waktu penanganan atau durasi yang dihabiskan pemangsa pada mangsa yang ditangkap untuk dikonsumsi, merupakan salah satu parameter dari banyak model respons fungsional (Papanikolaou et al, 2020) dan mengasumsikan bahwa predator menyesuaikan waktu penanganan untuk memaksimalkan kebugarannya (Louapre et al, 2018). Suhu sekitar dapat mempengaruhi tingkat metabolisme serangga (Stefan & Jonathan, 2019) yang secara tidak langsung juga mempengaruhi waktu penanganan mangsa (Daugaard et al 2019) dan tingkat mencari makan (Sentis & Boukal, 2018). Sifat parasitoid akan cenderung mengurangi aktifitas dalam memarasit inangnya pada suhu yang rendah serta akan meningkat seiring dengan meningkatnya suhu.…”