The Arctic tundra biome is undergoing rapid shrub expansion (‘shrubification’) in response to anthropogenic climate change. During the previous ~2.6 million years, glacial cycles caused substantial shifts in Arctic vegetation, leading to changes in species' distributions, abundance and connectivity, which have left lasting impacts on the genetic structure of modern populations. Examining how shrubs responded to past climate ch...

The transfer of energy through zooplankton grazing on phytoplankton is one of the most important interactions in aquatic ecosystems, yet the role of hydrodynamic forces is not fully understood. Factors that influence these interactions include algal size and shape and the interactions between grazer and alga dictated by hydrodynamic forces. Hydrodynamic forcing lead to unimodal relationships in grazer clearance rates (CR) beca...

Unionid mussels from clear‐water rivers are often found in turbid waters in which their feeding and reproductive efficiency should be impaired. We examined the feeding response of Lampsilis siliquoidea from a clear and turbid river in response to increased concentrations of total suspended solids (TSS) and water velocity in a funnel chamber and a recirculating flow chamber. Four TSS concentrations (0, 5, 20, and 100 mg L −1 )...

Aim Seasonally dry tropical forest ( SDTF ) of the Caribbean Islands (primarily West Indies) is floristically distinct from Neotropical SDTF in Central and South America. We evaluate whether tree species composition was associated with climatic gradients or geographical distance. Turnover (dissimilarity) in species composition of different islands or among more distant sites would suggest communities structured by speciation a...

The circumpolar expansion of woody deciduous shrubs in arctic tundra alters key ecosystem properties including carbon balance and hydrology. However, landscape‐scale patterns and drivers of shrub expansion remain poorly understood, inhibiting accurate incorporation of shrub effects into climate models. Here, we use dendroecology to elucidate the role of soil moisture in modifying the relationship between climate and growth for...

Benthic suspension feeders such as dreissenid mussels ( Dreissena polymorpha and D . rostriformis bugensis ) are often found in remarkably dense aggregations (i.e. > 10 5 mussels m − 2 ), which is surprising, given their high clearance rates and limited mixing within the benthic boundary layer. Results from flow visualization in flow chamber experiments indicate that there is indeed limited mixing around mussel aggregations at...

We examined the dispersal of larvae (glochidia) of a common unionid mussel species, Actinonaias ligamentina , which need to attach to a host fish in order to develop into juveniles, in a lowland river (Sydenham River, Ontario, Canada). Generally, the decline in the number of glochidia captured with distance from release was best described by an inverse power function. The highest proportion was found in the first net 4 m downs...

Local bed shear stress (Τ w ) is a fluid dynamic parameter of importance in determining the physical and biological characteristics of stream‐bed environments. Unfortunately, it is often difficult to measure Τ w under field conditions. Herein we describe the use of a Preston‐static tube, which is essentially a surface‐mounted Pitot‐static tube, to measure Τ w in mountain streams. Our results indicate that it is possible to mea...

We conducted a field study including a series of cruises over an isolated offshore zebra mussel reef (7–11 m deep) in Western Lake Erie to examine the effect of zebra mussels ( Dreissena spp.) on the water column. The horizontal currents over the reef were found to be primarily due to the hydraulic flow and surface gravitational seiches. The turbulence generated by these currents was found to be too weak to fully mix the water...