Gauging oxygen risk and tolerance for the megafauna of the Southern California shelf based on in situ observation, species mobility, and seascape

Oxygen decline poses increasing risks to global shelf communities. This study was conducted to measure species oxygen exposures in situ and to assess risks of low oxygen based on the hypothesis that species risk varies spatially and is dependent on the interaction of shelf oxygen dynamics with habitat pattern, species mobility, and tolerance to low oxygen. Here, we report concomitant observations of oxygen, depth, and habitat for the most common benthic and epibenthic megafauna on the southern California shelf (30–125 m). The study was conducted when oxygen concentrations were the lowest observed within the previous 30 years off southern California (2012–2014), yet hypoxic conditions (<1.42 ml l−1) were not observed. No significant oxygen exposure differences were observed among highly mobile, mobile, and sessile species due to the dynamic nature of the oxycline. Habitat affinities for the most abundant benthic megafauna (53 taxa) were discriminated among four different habitats. Highly mobile rockfish (Sebastidae) exhibited distributions suggesting less tolerance to low oxygen than most other taxa. Given the mosaic of consolidated and coarse-grained habitats that rockfish prefer, the onset of hypoxic conditions near the shelf break (∼90–120 m) would likely compress local rockfish populations into less favourable habitat in a non-linear fashion.

Springtails (Collembola) in meadows, pastures and road verges in Central Finland

Understanding of species distribution, abundance and habitat affinities is crucial for red-list assessment, conservation and habitat management. In Central Finland, we studied Collembola in three habitat types, namely non-grazedmeadows, pastures and road verges using pitfall traps. Altogether, 9,630 Collembola individuals were recorded. These belonged to 12 families, 34 genera and 60 species. The number of specimens was clearly higher in meadows than in pastures or road verges. The number of species, however, was higher in meadows and road verges (40 and 39 species, respectively) than in pastures (33 species). The overall species number is comparable to other large-scale sampling schemes in similar habitats. We recorded a few abundant species (Spatulosminthurus flaviceps, Sminthurus viridis and Sminthurus nigromaculatus) that have been previously recorded from very different biotopes. In conclusion, biodiversity inventories of soil fauna, as well as other biota, should also include marginal habitats, which often host peculiar communities.

Revision of the calcareous fen arachnofauna: habitat affinities of the fen-inhabiting spiders

Calcareous fens are one of the most species-rich habitats of the temperate zone of the Northern Hemisphere. In spite of this species richness, however, calcareous fens are still rather poorly investigated. Consequently, the data of the fen-associated spider fauna are also largely lacking. The aim of the research was to study the spider fauna of the calcareous fens of Latvia and to draw conclusions about what kind of spider species and ecological groups typically inhabit calcareous fen habitats. Spiders were sampled in the summer months of 2010, 2011, and 2012 at nine different calcareous fens of the coastal lowland of Latvia. The spider collection was performed by pitfall traps and a sweep net. The examined material comprised 6631 adult spider individuals representing 21 families and 149 species. The main spider ecological groups that dominated in the studied calcareous fens were hygrophilous and photophilous species which largely reflect the main properties of our studied habitats, all of which were wet, open mire habitats. Nevertheless, the fen arachnofauna consisted also of spider groups which are less typical for moist, sun-exposed, and alkaline environments, like xerophilous, sciophilous, and sphagnophilous species, respectively. Finally, several spider species collected in this study have not been previously reported for the spider fauna of Latvia, and many more might still be undiscovered in these unique and poorly investigated habitats. Therefore, it is suggested that calcareous fens deserve special attention and they should definitely be investigated further.