Countless organisms live on our planet. However, this biodiversity is threatened by human dominance. In particular, genetic diversity, species diversity and ecosystem diversity are affected. The main reasons for the rapid decline in biodiversity are climate change, large-scale land-use change, direct exploitation, pollution and the spread of invasive alien species. Freshwater species – from larger animals (“megafauna”), fish, amphibians, invertebrates, macrophytes to a variety of microorganisms (e.g. plankton, bacteria, fungi and viruses) – are particularly affected by these pressures. In this context, aquatic biodiversity contributes to the stability and resilience of ecosystems in the context of global change, and plays a central role in important ecosystem services such as water purification, food supply and recreational opportunities.
In the programme area “Biodiversity in a Changing World”, IGB engages in research on the drivers and implications of biodiversity loss and on how biodiversity can be conserved. The focus is on lakes, rivers and wetlands in general, including small freshwater habitats such as ponds and streams, as well as feedback mechanisms between aquatic and terrestrial systems.
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One-quarter of freshwater fauna threatened with extinction
The largest global assessment of freshwater animals on the IUCN Red List of Threatened Species to date has revealed that 24 per cent of the world’s freshwater fish, dragonfly, damselfly, crab, crayfish and shrimp species are at high risk of extinction.
Collective anti-predator escape manoeuvres through optimal attack and avoidance strategies
The research team investigated the predator-prey behaviour of striped marlins (Kajikia audax) and sardine shoals (Sardinops sagax caerulea) in the open ocean. Their findings reveal that individual prey in groups follows simple decision-making rules, which lead to complex, collective self-organized manoeuvers – and that this response is something predators can capitalize on.
A conceptual classification scheme of invasion science
Combining expert knowledge with literature analysis, this study developed a conceptual classification scheme of invasion science that allows to organize publications and data sets, guide future research, and identify knowledge gaps. The scheme features 5 major themes of invasion science that are divided into 10 broader research questions and linked to 39 major hypotheses of the field.
Evidence for a by-product mutualism in a group hunter depends on prey movement state
Why do animals hunt in groups? The authors have shown in a field study in the ocean off Mexico: the faster the prey school moves, the higher the capture rate of the striped marlin. This is because if the prey school is moving fast, individual prey fish are more likely to become isolated. These isolated fish are then easily caught by the non-attacking marlins, an advantage of group hunting.
Rapid growth and the evolution of complete metamorphosis in insects
Insects undergo complete metamorphosis, rebuilding their bodies, such as the transition from caterpillar to chrysalis to butterfly. The authors wondered why this extreme lifestyle might have evolved. Combining growth data and mathematical modelling, they found that insects grow much faster if they can grow and build the adult body in two separate stages, rather than doing both continuously.