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How does the surrounding terrestrial landscape affect the dispersal of pond-dwelling organisms? Although some studies suggest that small aquatic crustaceans can disperse efficiently across a range of intervening environments, other work has pointed to dispersal limitation, especially over large distances. Czech researchers examined the passive dispersal of microcrustaceans (cladocerans, copepods, and ostracods) by comparing communities […]
December 13, 2016
Comments Off on Factoring history into threat assessments
Genetic variation allows populations to adapt to environmental changes, and it’s often the case that threatened species exhibit low genetic diversity. Human-produced habitat fragmentation is a well-recognised cause of genetic bottlenecks, but the additional effects of larger-scale biogeographic factors are rarely considered. As an example of such biogeographic impacts, populations that have managed to survive […]
December 13, 2016
Comments Off on Deciding on sites for conservation
Biodiversity conservation is hampered by the fact that many species haven’t been described and most species ranges haven’t been mapped. As a result, in selecting sites for protection, natural resource managers often resort to the use of surrogate indicators for the species that they wish to conserve. Surrogates may be other, more common, species, or […]
December 13, 2016
Comments Off on Top predator boosts species richness – but not in alien ecosystems
The spiny water flea Bythotrephes longimanus is a large cladoceran, a specialised carnivore and a top predator. Invasions of North American lakes by Bythotrephes have been linked to dramatic changes in food web structure and reductions in species diversity, which seems to contradict the expectation that top predators increase the evenness and diversity of aquatic […]
June 1, 2016
Comments Off on Remote surveillance:monitoring fish populations
Submerged vegetation provides freshwater animals with food, substrate and refuge opportunities. Although the structural complexity of aquatic vegetation can make it difficult for researchers to study the behaviour of resident species and measure the size of their populations, the advent of high-resolution, low-light video systems promises to alleviate these problems. Working in Florida, researchers carried […]
June 1, 2016
Comments Off on “Cosmopolitan” species are often alien invaders
Our ability to manage species invasions is often compromised by a lack of knowledge as to which species are actually aliens and which are natives. This is especially true in the case of animal groups containing small, poorly- studied species. In the absence of solid information, many such taxa have been uncritically assumed to have […]
March 23, 2016
Comments Off on Adding wood to streams: when is it worthwhile?
Placing woody material into waterways with the aim of improving habitat quality is a common stream restoration technique. However, debate continues around the extent to which wood placement actually leads to significant increases in fish abundance. In a wide-ranging literature review, American ecologists note that many researchers reported that the installation of instream structures was […]
June 19, 2017
Comments Off on How the terrestrial landscape affects aquatic dispersal