Nina Bednaršek

Biogeography and genetic diversity of the atlantid heteropods

Highlights • We present a global biogeography and mtCO1 phylogeny for all atlantid morphospecies.• An updated biogeography for all morphospecies is constructed from museum collections.• Phylogeny of 437 new and 52 published sequences revealed 33 clades, 10 that are new.• Some new clades have unique morphological characters and may represent new species.• New clades have distinct distributions, suggesting narrow environmental tolerances.

Role of Technology in Ocean Acidification: Monitoring, Water-Quality Impairments, CO 2 Mitigation, and Machine Learning

Ocean acidification (OA), or the reduction in the pH of the ocean, is driven by increasing carbon dioxide concentration in the atmosphere and local pollution. There is already evidence of the detrimental impact of OA on marine organisms. As further increases in atmospheric CO 2 and changes in water quality are expected, it is crucial to develop and implement advanced technologies that enable better monitoring, allow for understanding of adaptation potential of the organisms, and facilitate the use of mitigation strategies toward predicted environmental changes. Collaboration of marine and computer scientists, engineers, and citizens is needed to develop innovative sustainable technologies to mitigate and reduce future increase of CO 2 .

Seawater carbonate chemistry and proportion of different dissolution levels in live juvenile Limacina helicina antarctica from the natural environment and ship-board incubations

The carbonate chemistry of the surface ocean is rapidly changing with ocean acidification, a result of human activities. In the upper layers of the Southern Ocean, aragonite-a metastable form of calcium carbonate with rapid dissolution kinetics-may become undersaturated by 2050. Aragonite undersaturation is likely to affect aragonite-shelled organisms, which can dominate surface water communities in polar regions. Here we present analyses of specimens of the pteropod Limacina helicina antarctica that were extracted live from the Southern Ocean early in 2008. We sampled from the top 200 m of the water column, where aragonite saturation levels were around 1, as upwelled deep water is mixed with surface water containing anthropogenic CO2. Comparing the shell structure with samples from aragonite-supersaturated regions elsewhere under a scanning electron microscope, we found severe levels of shell dissolution in the undersaturated region alone. According to laboratory incubations of intact samples with a range of aragonite saturation levels, eight days of incubation in aragonite saturation levels of 0.94-1.12 produces equivalent levels of dissolution. As deep-water upwelling and CO2 absorption by surface waters is likely to increase as a result of human activities, we conclude that upper ocean regions where aragonite-shelled organisms are affected by dissolution are likely to expand.