Meroplankton

Meroplankton are a wide variety of aquatic organisms which have both a planktonic stage and at least one other component, such as benthic or nektonic, in their life cycles.

Depending on the particular species and the environmental conditions, larval or juvenile-stage meroplankton may remain in the pelagic zone for durations ranging from hour to months.

One study conducted in a Patagonian Fjord found that species composition of the meroplankton community depended on the seasonally varying input levels from the Baker river as well as vertical and horizontal stratification of the water column.

Currents play a key role in delivering larval organisms to specific settlement locations, where they are able to transition and mature into adult forms.

In order to ensure that larvae have sufficient sources of nutrition, many species coordinate larval release with times of algal blooms.

This synchronicity between release of larvae and algal blooms often leads to meroplankton making up the largest percentage of the planktonic community during such reproductive periods.

Deep oceanic waters show significantly lower abundance than shelf regions, due to poor light penetration.

[14] Water and benthos pollution from industrial sources has been demonstrated to have varying effects on biological diversity and survival potential of meroplankton.

One study conducted in the Vostok Bay region in Russia, demonstrated that even in the presence of industrial pollutants, most species of meroplankton were able to proliferate almost unaffected.

The authors of this study attribute these findings to the fact that meroplankton are transported by ocean currents generally from cleaner open waters inshore.

However, the rate of recolonization was demonstrated to be notably slow, on average taking about 10 years before the abundance and diversity of meroplankton returned to its original levels.

Assemblage of planktonic organisms
Icefish larva
Larva stage of a spiny lobster
Early larval state of a sea urchin larva (drawing by Haeckel )