BELGIAN JOURNAL OF ZOOLOGY

Publisher:: —
ISSN:: 0777-6276
Category:: ZOOLOGY
Impact factor:: 1.3

Official website ↗Official RSS source ↗

Feed status

2 parsed articles

Last update: Not fetched

Latest articles

Divergent isotopic niches of sister species of the Antarctic amphipod genus Charcotia

2025-05-28

Dorien Aerts, Aaron Kolder, Gilles Lepoint, Loïc N. Michel, Isa Schön

Climate change and resource exploitation in the Southern Ocean are important anthropogenic pressures on Antarctic food webs. Understanding the eco-functional roles of Antarctic communities is essential for ecosystem management and conservation. Amphipods are among the most dominant and ecologically important benthic taxa in the Southern Ocean. The amphipod genus Charcotia is part of the scavenger guild playing a dominant role in nutrient recycling. To study the trophic habits of two sister species C. amundseni and C. obesa , stable isotope ratios of carbon and nitrogen were measured along geographical and bathymetrical gradients. Charcotia obesa belongs to the fourth and C. amundseni to the fifth trophic level, based on significant differences in δ15N values. Both benthic and pelagic primary producers dominate the diet in both species as derived from their low δ13C values. Charcotia obesa , the species with the narrowest depth range of the two studied species, did not show a depth-related pattern in isotopic ratios. An increasing geographic gradient of both δ15N and δ13C values was observed for C. obesa , ranging from the northern most tip of the Western Antarctic Peninsula to the southwestern most part in the Bellingshausen Sea. This might be linked to nutrient rich glacial meltwater in the latter part of the Southern Ocean. Nitrogen stable isotope ratios of C. amundseni showed a significant difference between Crown Bay and the other locations; this might be explained by the close location of the Filchner Area to nutrient rich upwelling in the Weddell Sea Gyre. Our study provides evidence for niche differentiation between two closely related amphipod species. Incorporation of additional samples from other locations and depth ranges in combination with isotope analysis and DNA-based prey identification might clarify the trophic position of benthic amphipods.

The role of skin colour in camouflage: experiment with green plasticine models of the European tree frog Hyla arborea

2025-01-10

Jenő J. Purger, Bianka Pál-Dittrich, Dávid Szép, Krisztián Samu

The role of skin colour variations in the survival of European tree frogs is unknown. We presumed that green frogs become more noticeable to predators in the autumn when the colour of the leaves changes. For the study of their survival chance, we made plasticine models of European tree frogs with the same shape and the same dominant colour spectrum of 550 nm. The experiment was conducted in autumn 2018 in three vegetation types with varied backgrounds (vineyard, bulrush belts and reed bed) and in the habitat with a permanent background (concrete wall). In our experiment lasting more than a month we used 50 green coloured tree frog plasticine models in every habitat. Only 10% of the models were damaged by predators. Daily survival rates were high in all habitats (above 99%), and predation pressure on the concrete wall was significantly higher than in the different vegetation types. This was caused by the fact that the colour contrast of frog models on concrete walls (13.3) was twice as high as on grape (6.8), bulrush (4.2), or reed (5.0) leaves. Predators in the vineyard, bulrush belts and reed bed were mostly birds which left traces primarily on the heads of the models, while on the models displayed on the wall most of the traces (on the trunk and limbs) were left by mammals (small mammals, red foxes, and domestic cats). The colour spectrum of the vegetation background of the European tree frog models changed to brownish in autumn, but predation pressure did not increase. The constant green colour of the European tree frog models in natural habitats did not affect predation, from which we conclude that the colour variants may have other functions besides camouflage.