Spring bloom

[2] In addition, there is a lag in the grazing response of herbivorous zooplankton at the start of blooms, which minimize phytoplankton losses.

However, with the exception of coastal waters, it can be argued, that iron (Fe) is the most limiting nutrient because it is required to fix nitrogen, but is only available in small quantities in the marine environment, coming from dust storms and leaching from rocks.

However, vertical mixing also causes high losses, as phytoplankton are carried below the euphotic zone (so their respiration exceeds primary production).

This spurs phytoplankton growth, leading to the onset of the North Atlantic spring bloom 20-30 days earlier than would occur with thermal stratification alone.

This northward progression is because spring occurs later, delaying thermal stratification and increases in illumination that promote blooms.

Also, grazing pressure tends to be lower because the generally cooler temperatures at higher latitudes slow zooplankton metabolism.

Succession occurs because different species have optimal nutrient uptake at different ambient concentrations and reach their growth peaks at different times.

[citation needed] For example, in oceanic environments, diatoms (cells diameter greater than 10 to 70 μm or larger) typically dominate first because they are capable of growing faster.

[2] Ultraphytoplankton can sustain low, but constant stocks, in nutrient depleted environments because they have a larger surface area to volume ratio, which offers a much more effective rate of diffusion.

[1][2] The types of phytoplankton comprising a bloom can be determined by examination of the varying photosynthetic pigments found in chloroplasts of each species.

[2] Variability in the patterns (e.g., timing of onset, duration, magnitude, position, and spatial extent) of annual spring bloom events has been well documented.

[3][5] These variations occur due to fluctuations in environmental conditions, such as wind intensity, temperature, freshwater input, and light.

Oviatt et al. (2002)[4] noted a reduction in spring bloom intensity and duration in years when winter water temperatures were warmer.

Oviatt et al. suggested that the reduction was due to increased grazing pressure, which could potentially become intense enough to prevent spring blooms from occurring altogether.