Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

The influence of articulated and disarticulated cockle shells on the erosion of a cohesive bed

An annular flume (Lab Carousel) was used to investigate the influence of shells on the erosion rates of an artificial laboratory cohesive bed (potters clay) under unidirectional flow. Specimens of articulated and disarticulated cockle shells (Cerastoderma edule), separated into six size classes (of maximum diameter from 13 to 26 mm), were used. The fluid-transmitted shear stresses and shell-induced bed erosion for the six classes were measured in triplicate, as well as shell settling velocity, sedimentation diameter, and shell drag coefficient. Bed erosion began after the shells started to move: erosion rates were influenced by shell size and the mode of transport. Two different modes of shell transport were observed: (i) rolling and saltation of articulated shells, and (ii) sliding and saltation of disarticulated shells. Peak bed erosion rates were associated with rolling and sliding modes of transport. Higher values of the solid-transmitted shear stress were calculated for saltating shells (in some cases two times higher), but contact with the bed was less frequent than rolling or sliding. The presence of cockle shells in an environment with hydrodynamic conditions strong enough to induce shell transport could significantly increase the loss of mass (erosion) of the surface bed or cliff. At Hythe intertidal area, where the shell specimens were collected, the presence of miniature furrows containing shells deposits in the troughs is widespread, and the troughs and walls show tool marks indicating shell abrasion