Does Size Matter? Toxicity Effects of 5‐nm and 70‐nm Silver Nanoparticles on Hoplobatrachus Rugulosus Frog

With the increased usage of silver nanoparticles (AgNPs), the potential impacts of released AgNPs in the environment are increasingly concerned, especially to natural living organisms. Since the properties of AgNPs significantly depend on their sizes, this work aimed to compare the effects of 5-nm and 70‐nm AgNPs on toxicity and bioaccumulation in Hoplobatrachus rugulosus, the edible East Asian Bullfrog. The synthesized AgNPs were characterized by X‐ray diffraction and selected area electron diffraction analyses. Both 5‐nm and 70‐nm AgNPs caused mortality, reduced growth, induced abnormal development, generated cellular oxidative stress, and modulated cellular biomolecule pattern of frog embryos, but at different levels. The 5‐nm AgNPs caused harmful effects on the frog embryos more than 70-nm AgNPs, likely due to their small size to allow more accessibility into the cell. The mortality effects of AgNPs depended on the concentration, exposure time, and size. The malformation of frog embryos in response to AgNPs-exposure included scoliosis, lordosis, kyphosis, and yolk sac edema. Synchrotron Fourier transformed infrared analyses revealed that 5‐nm AgNPs significantly changed the profile of cellular biomolecules in the embryos, indicated by the spectral peaks assigned to lipid, carbohydrates, proteins, and nucleic acids. The bioaccumulation of silvers was dominant in eggs, followed by stomach, liver, kidney, and intestine, respectively, suggesting their translocation via blood circulation. The result of high accumulated silver in eggs and effects on embryonic mortality, growth, development, and cellular changes suggested the potential negative impacts of AgNPs on the sustainability of this frog in the environment.

Does Size Matter? The Case of the Courtship Pyramids in Red Sea Ghost Crabs (Ocypode saratan)

Display, wherein males attempt to maximize fitness by attracting sexually mature females to mate, is known to drive speciation by Sexual Selection. We researched the Red Sea Ghost Crab (Ocypode saratan; RSGC), in which males build display pyramids to attract females. The study was conducted at the beach in Eilat, Israel. At each session, we measured the height (in cm) of all pyramids and the dimensions (height, breadth; in cm) of the burrow entrance. We assumed that the size of the entrance represented the relative size of the carapace width of the occupant. The mean (± SE) entrance volume was 230.8 ± 11.7 cm, and the height of the pyramid was 11.8 ± 0.49 cm (n = 54). The results of our study did not support our hypothesis because we had expected to find a linear correlation between body size and pyramid height, i.e., the larger the male, the larger the pyramid. However, our results show that the largest males in the population either built small pyramids or not at all, and the cut-off of the larger crab’s body size appears to be around 350 cm3. We discovered a step-wise function in the data in that crabs with the smallest body size of ca. 250 cm3 constructed the highest pyramids, with a declining tendency between 250–350 cm3 and extremely low pyramids beyond 350 cm3. However, our findings need to be further studied with a stress on the ambiance and elucidate whether the habitats differ in temperature, humidity, prey-base, etc., before concluding as to why the larger males desist from building pyramids. This study underwrites the importance of studying the mating systems of the macro-fauna of the beaches that are fast disappearing owing to anthropogenic development.