Impacts of Warming on Reciprocal Subsidies Between Aquatic and Terrestrial Ecosystems

Cross-ecosystem subsidies are important as their recipients often rely on them to supplement in situ resource availability. Global warming has the potential to alter the quality and quantity of these subsidies, but our knowledge of these effects is currently limited. Here, we quantified the biomass and diversity of the invertebrates exchanged between freshwater streams and terrestrial grasslands in a natural warming experiment in Iceland. We sampled invertebrates emerging from the streams, those landing on the water surface, ground-dwelling invertebrates falling into the streams, and those drifting through the streams. Emerging invertebrate biomass or diversity did not change with increasing temperature, suggesting no effect of warming on aquatic subsidies to the terrestrial environment over the 1-month duration of the study. The biomass and diversity of aerial invertebrates of terrestrial origin landing on the streams increased with temperature, underpinned by increasing abundance and species richness, indicating that the greater productivity of the warmer streams may attract more foraging insects. The biomass of ground-dwelling invertebrates falling into the streams also increased with temperature, underpinned by increasing body mass and species evenness, suggesting that soil warming leads to terrestrial communities dominated by larger, more mobile organisms, and thus more in-fall to the streams. The biomass and diversity of terrestrial invertebrates in the drift decreased with temperature, however, underpinned by decreasing abundance and species richness, reflecting upstream consumption due to the higher energetic demands of aquatic consumers in warmer environments. These results highlight the potential for asynchronous responses to warming for reciprocal subsidies between aquatic and terrestrial environments and the importance of further research on warming impacts at the interface of these interdependent ecosystems.

Effects of Thermal Acclimation on the Tolerance of Bactrocera zonata (Diptera: Tephritidae) to Hydric Stress

Insects, similarly to other small terrestrial invertebrates, are particularly susceptible to climatic stress. Physiological adjustments to cope with the environment (i.e., acclimation) together with genetic makeup eventually determine the tolerance of a species to climatic extremes, and constrain its distribution. Temperature and desiccation resistance in insects are both conditioned by acclimation and may be interconnected, particularly for species inhabiting xeric environments. We determined the effect of temperature acclimation on desiccation resistance of the peach fruit fly (Bactrocera zonata, Tephritidae) – an invasive, polyphagous pest, currently spreading through both xeric and mesic environments in Africa and the Eurasian continent. Following acclimation at three constant temperatures (20, 25, and 30°C), the survival of adult flies deprived of food and water was monitored in extreme dry and humid conditions (<10 and >90% relative humidity, respectively). We found that flies acclimated at higher temperatures were significantly heavier, and contained more lipids and protein. Acclimation temperature significantly and similarly affected the survival of males and females at both high and low humidity conditions. In both cases, flies maintained at 30°C survived longer compared to 20 and 25°C – habituated counterparts. Regardless of the effect of acclimation temperature on survival, overall life expectancy was significantly shortened when flies were assayed under desiccating conditions. Additionally, our experiments indicate no significant difference in survival patterns between males and females, and that acclimation temperature had similar effects after both short (5–10 days) and long (11–20 days) acclimation periods. We conclude that acclimation at 30°C prolongs the survival of B. zonata, regardless of ambient humidity levels. Temperature probably affected survival through modulating feeding and metabolism, allowing for accumulation of larger energetic reserves, which in turn, promoted a greater ability to resist starvation, and possibly desiccation as well. Our study set the grounds for understanding the phenotypic plasticity of B. zonata from the hydric perspective, and for further evaluating the invasion potential of this pest.

Modelling the visual world of a velvet worm

In many animal phyla, eyes are small and provide only low-resolution vision for general orientation in the environment. Because these primitive eyes rarely have a defined image plane, traditional visual-optics principles cannot be applied. To assess the functional capacity of such eyes we have developed modelling principles based on ray tracing in 3D reconstructions of eye morphology, where refraction on the way to the photoreceptors and absorption in the photopigment are calculated incrementally for ray bundles from all angles within the visual field. From the ray tracing, we calculate the complete angular acceptance function of each photoreceptor in the eye, revealing the visual acuity for all parts of the visual field. We then use this information to generate visual filters that can be applied to high resolution images or videos to convert them to accurate representations of the spatial information seen by the animal. The method is here applied to the 0.1 mm eyes of the velvet worm Euperipatoides rowelli (Onychophora). These eyes of these terrestrial invertebrates consist of a curved cornea covering an irregular but optically homogeneous lens directly joining a retina packed with photoreceptive rhabdoms. 3D reconstruction from histological sections revealed an asymmetric eye, where the retina is deeper in the forward-pointing direction. The calculated visual acuity also reveals performance differences across the visual field, with a maximum acuity of about 0.11 cycles/deg in the forward direction despite laterally pointing eyes. The results agree with previous behavioural measurements of visual acuity, and suggest that velvet worm vision is adequate for orientation and positioning within the habitat.

Do pesticide residues have enduring negative effect on macroinvertebrates and vertebrates in fallow rice paddies?

Rice is one of the most important staple food in the world, with irrigated rice paddies largely converted from natural wetlands. The effectiveness of rice fields in help preserve species depends partially on management practices, including the usage of pesticides. However, related studies have focused predominately on the cultivation period, leaving the effects of soil pesticide residues on aquatic invertebrates during the fallow periods little explored; other animals, such as waterbirds, also rely on aquatic invertebrates in flooded fallow fields for their survival. We therefore investigated vertebrates and macroinvertebrates (terrestrial and aquatic) on rice stands and in flooded water during cultivation and fallow periods in organic and conventional rice fields in Taiwan. Association of environmental factors with terrestrial and aquatic organisms was also analyzed. In total, 32,880 individuals of 144 invertebrate families and 381 individuals of 15 vertebrate families were recorded after nine samplings each for six organic and six conventional rice fields. Family richness and abundance of all invertebrates (terrestrial and aquatic) were higher in organic than in conventional fields during the cultivation period, but were similar between the two agricultural practices during the fallow period. Richness and abundance of terrestrial invertebrates in both organic and conventional fields increased with the progression of rice cultivation, so did the differences between the two practices. Richness of aquatic invertebrates was mostly constant across the sampling period, while abundance increased but differences decreased during the fallow period. Richness and abundance of terrestrial invertebrates were positively associated with ambient temperature and height of rice stand. Abundance of aquatic invertebrates were positively associated with pH value and amount of dissolved oxygen but negatively associated with water temperature. Richness and abundance of all vertebrates and each of the constituting groups (fish, amphibian, reptile, bird, and migratory waterbird) were statistically similar between the two practices although abundance of migratory waterbirds in organic fields were two times those in conventional fields during the fallow period. Our study suggested accumulated effects of pesticides on suppressing terrestrial invertebrates during the cultivation period, but diminishing effects of pesticide residues on repressing aquatic invertebrates during the fallow period. This comprehensive study provided a holistic picture on macroinvertebrate and vertebrate fauna, as well as ramifications of pesticide usage, in a representative Southeast Asia rice paddy ecosystem. Further study should compare rice fields with natural wetlands to better assess how to capitalize on agroecosystems for biodiversity conservation.

Policy and objectives of the New Zealand Arthropod Collection

The New Zealand Arthropod Collection (NZAC) is the world’s largest taxonomic collection of terrestrial invertebrates from New Zealand. The NZAC policy is presented that defines the vision for the collection of being managed to the highest international standards, connected through a global infrastructure, and providing high quality, authoritative, and trusted information. The policy also provides context and guidelines for collection activities, and twenty-two objectives are outlined that will be completed over the next 5 years.

Temporal Aspect of the Terrestrial Invertebrate Response to Moisture Dynamic in Technosols formed after Reclamation at a Post-Mining Site in Ukrainian Steppe Drylands

Different approaches were applied to assess soil moisture optima and tolerance of the ecological niche temporal projection of terrestrial invertebrates within an experimental polygon created to investigate the reclamation processes after deep underground hard-rock mining in the Ukrainian steppe drylands. Sampling was carried out in 2013–2015 on a variant of artificial soil (technosols). To investigate the spatiotemporal variation in the abundance, species richness and species composition of invertebrate assemblages the animals were sampled using pitfall traps. The readily available water for plants, precipitation, wind speed, atmospheric temperature, atmospheric humidity, and atmospheric pressure were used as environmental predictors. The two-dimension geographic coordinates of the sampling locations were used to generate a set of orthogonal eigenvector-based spatial variables. Time series of sampling dates were used to generate a set of orthogonal eigenvector-based temporal variables. Weighted averaging, generalized linear mixed models, Huisman-Olff-Fresco models expanded by Jansen-Oksanen, correspondence analysis, and constrained correspondence analysis were used to estimate soil moisture species optima and tolerance. The moisture content in the technosols was revealed to be the most important factor determining the temporal dynamics of terrestrial invertebrate community in conditions of semi-arid climate and the ecosystem which formed as a result of the reclamation process. The species response to the soil water content is affected not only by the soil water content but also by the complex of the other environmental, temporal, and spatial factors. The effect of other factors on the species response must be extracted previously to find real estimations of the species optima and tolerance.