Ecology

Habitat

The habitat of Euphausia recurva is highly variable, being largely pelagic they can be found in all basins of the world and vary from purely oceanic habitats to reefs, continental slopes and even estuaries depending on currents and their life stage. Although Euphausia can populate depths of 4000m and more the majority of these species are much larger and species such as recurva tend to stay higher in the water column. They are also known to aggregate in great numbers in benthic areas for protection and mating and are restricted to subtropical areas (Brinton, et al. 2000).    

Vertical Distribution

The vertical distribution of krill in general varies significantly with many staying on the surface for their majority of their lives and others making regular migrations from great depths to the surface. E.recurva have been found at depths of over 1000m but are more commonly closer to 20m (Encyclopedia of Life). The vertical migration of euphausiaceans is commonly diurnal (occurs on a daily basis) but the timing and reasons behind it are unknown (Bary, 1956).  

Ecological significance

The euphausiaceans are thought to rival the biomass of the most abundant zooplankton on earth, the copepods (Santora, 2012). The euphausiaceans have an estimated biomass of 300 million tonnes throughout the world’s oceans and are undoubtedly a critical organism in transferring energy from the bottom of the food web (Everson, 2008). Krill are consumed by a wide range of predators, many of which primary feed on krill. These predators range from larval fish to large game fish such as tuna and marlin as well as marine mammals and birds. Their importance in these roles also emphasises their importance to humans as we rely on many of their predators as resources with many fisheries highly reliant of their presence such as the salmon, herring, tuna and sardine fisheries (Everson, 2008). Krill are also fast becoming a popular fishery for a combination of human and pet consumption due to their high nutrient value. The overfishing of this link in the food chain is likely to have disastrous consequences both in excess phytoplankton and limited food for higher level predators.

Picture (Whale Photos)