Can an acoustic observatory contribute to the conservation of threatened species?

Observatories are designed to collect data for a range of uses. The Australian Acoustic Observatory (A2O) was established to collect environmental sound, including audible species calls, from 344 recorders at 86 sites around Australia. We examine the potential of the A2O to monitor near threatened, threatened, endangered and critically endangered species, based on their vocal behaviour, geographic distributions in relation to the sites of the A2O and on some knowledge of habitat use. Using IUCN and EPBC lists of threatened and endangered species, we extracted species that vocalized in the audible range, and using conservative estimates of their geographic ranges, determined whether there was a possibility of hearing them at these sites. We found that it may be possible to detect up to 171 threatened species at sites established for the A2O, and that individual sites have the potential to detect up to 40 threatened species. All 86 sites occurred in locations where threatened species could possibly be detected, and the list of detectable species included birds, amphibians, and mammals. We have incidentally detected one mammal and four bird species in the data during other work. Threatening processes to which potentially detectable species were exposed included all but two IUCN threat categories. We concluded that with applications of technology to search the audio data from the A2O, it could serve as an important tool for monitoring threatened species.     

Body size variation among invertebrates inhabiting different canopy microhabitat: flower visitors are smaller

1. Factors such as reproductive fitness, climatic tolerance, predation pressure, energetic requirements and the quality and quantity of food sources all correlate with invertebrate body sizes. 2. This study examines body size variation between an invertebrate community inhabiting five different microhabitats (mature leaves, new leaves, flowers, fruit and suspended dead wood) that differ in quality, quantity, and availability in an Australian tropical rainforest canopy. 3. Mean body size varied significantly between invertebrate and beetle feeding guilds across microhabitats. Phylogenetically independent contrasts revealed that invertebrate taxonomic groups were significantly smaller on flowers than on mature and new leaves. Size differences between microhabitats were most pronounced among herbivorous taxa (Hemiptera, Lepidoptera). In particular, the immature stages or those groups that develop on flowers were significantly smaller on flowers and larger on leaves than expected. Taxonomic groups with many strong flying species, especially those that complete larval development on resources other than flowers, typically showed no differences in body size across microhabitats. 4. There are a number of potential hypotheses for the smaller body sizes of flower visitors, including: (i) differences in the physical sizes of the microhabitats; (ii) variation in time–dependent mortality risks that influence development times; and (iii) differences in the nutritional quality of the microhabitats, which can influence body size via metabolic pathways. 5. The findings of this study do not support hypothesis (i) (with the possible exception of one or two predatory groups). It is suggested that hypotheses (ii (time–dependent mortality factors) and particularly (iii) (nutritional variation) may be the best avenues for future study as the main drivers of body size differences between microhabitats.     

Colonization of subsurface microbial observatories deployed in young ocean crust

Oceanic crust comprises the largest hydrogeologic reservoir on Earth, containing fluids in thermodynamic disequilibrium with the basaltic crust. Little is known about microbial ecosystems that inhabit this vast realm and exploit chemically favorable conditions for metabolic activities. Crustal samples recovered from ocean drilling operations are often compromised for microbiological assays, hampering efforts to resolve the extent and functioning of a subsurface biosphere. We report results from the first in situ experimental observatory systems that have been used to study subseafloor life. Experiments deployed for 4 years in young (3.5 Ma) basaltic crust on the eastern flank of the Juan de Fuca Ridge record a dynamic, post-drilling response of crustal microbial ecosystems to changing physical and chemical conditions. Twisted stalks exhibiting a biogenic iron oxyhydroxide signature coated the surface of mineral substrates in the observatories; these are biosignatures indicating colonization by iron oxidizing bacteria during an initial phase of cool, oxic, iron-rich conditions following observatory installation. Following thermal and chemical recovery to warmer, reducing conditions, the in situ microbial structure in the observatory shifted, becoming representative of natural conditions in regional crustal fluids. Firmicutes, metabolic potential of which is unknown but may involve N or S cycling, dominated the post-rebound bacterial community. The archaeal community exhibited an extremely low diversity. Our experiment documented in situ conditions within a natural hydrological system that can pervade over millennia, exemplifying the power of observatory experiments for exploring the subsurface basaltic biosphere, the largest but most poorly understood biotope on Earth.     

‘Follow the Water’: Hydrogeochemical Constraints on Microbial Investigations 2.4 km Below Surface at the Kidd Creek Deep Fluid and Deep Life Observatory

Abstract

Microbiological and geochemical data are presented to characterize the hydrogeochemistry and to investigate extant microbial life in fracture waters 2.4?km below surface, at the Kidd Creek Observatory in Canada. Previous studies identified the world’s oldest groundwaters with mean residence times on the order of millions to billions of years trapped in fractures in Precambrian host rock here. In this study, major ion chemistry, δ¹⁸O and δ²H isotopic signatures and dissolved gases in the fracture waters are shown to be distinct from potential contamination end-members, demonstrating the fracture waters are not impacted by waters used in mining operations. A previous work on sulfur isotope signatures suggested a longstanding indigenous population of sulfate-reducing bacteria in these highly reducing fluids and sufficient sulfate to support microbial activity. Here, we report the first evidence for extant visible and cultivable microbial life at this location. Anaerobic metabolisms were investigated using the Most Probable Number (MPN) method. The fracture fluids contained extant cells at low biomass density (～10³–10⁴ cells/mL) and showed a strong response from autotrophic sulfate-reducers and alkane-oxidizing sulfate reducers. These lines of evidence provide the interpretational framework (chemical, hydrogeologic, and microbiologic) essential to the on-going genomic and metagenomic investigations at the Kidd Creek Observatory – the world’s most longstanding location for investigation of subsurface fluids and deep life at such profound depth.