Philosophical Transactions of the Royal Society B 365: 3215–3226. (1992) indicated that a 2 °C increase in water temperature resulted in a three-week shift in the maturation of the copepod, Acartia hudsonica, which could significantly increase zooplankton grazing intensity. This northward progression is because spring occurs later, delaying thermal stratification and increases in illumination that promote blooms.  However, new explanations have been offered recently, including that blooms occur due to: At greater latitudes, spring blooms take place later in the year. Phytoplankton Bloom Phytoplankton account for nearly half of the global primary production (45-50 Gt C/year, Longhurst et al.  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. Increasing light intensity (in shallow water environments). However, vertical mixing also causes high losses, as phytoplankton are carried below the euphotic zone (so their respiration exceeds primary production). , Spring blooms typically last until late spring or early summer, at which time the bloom collapses due to nutrient depletion in the stratified water column and increased grazing pressure by zooplankton. environmental) factors. This means phytoplankton must have light from the sun, so they live in the well-lit surface layers of oceans and lakes. Phytoplankton(or algae) are tiny, single-celled plants. Oviatt et al. First, because freshwater is less dense, it rests on top of seawater and creates a stratified water column. Introduction. Results are consistent with critical depth hypothesis if mixing depth is considered. Townsend, D.W., Cammen, L.M., Holligan, P.M., Campbell, D.E., Pettigrew, N.R. In terms of reproduction, many species of phytoplankton can double at least once per day, allowing for exponential increases in phytoplankton stock size. Blooms can also occur in summer and fall when there is an increase in nutrients from natural sources, such as wind-driven mixing of surface waters with deeper waters, or human sources, such as wastewater treatment plants. ). Color variations in the plume are caused by different water depths (the coccolithophores in the plume can live at depths of up to 50 meters below the surface) and different phytoplankton concentrations. Laws University of Hawaii, Oceanography Department, and Hawaii Institute of Marine Biology 1000 Pope Road, Honolulu 96822 Abiotic factors include light availability, nutrients, temperature, and physical processes that influence light availability, and biotic factors include grazing, viral lysis, and phytoplankton physiology. Phytoplankton spring blooms often consist of large diatoms inedible for zooplankton, but the zoospores of their fungal parasites may serve as a food source for this higher trophic level. As a result, vertical mixing is inhibited and phytoplankton and nutrients are entrained in the euphotic zone. Along with thermal stratification, spring blooms can be triggered by salinity stratification due to freshwater input, from sources such as high river runoff. Rapid increases in phytoplankton growth, that typically occur during the spring bloom, arise because phytoplankton can reproduce rapidly under optimal growth conditions (i.e., high nutrient levels, ideal light and temperature, and minimal losses from grazing and vertical mixing). "The impact of changing climate on phenology, productivity, and benthic-pelagic coupling in Narragansett Bay". stock) that typically occurs in the early spring and lasts until late spring or early summer?  Phosphorus can also be limiting, particularly in freshwater environments and tropical coastal regions.. , Links have been found between temperature and spring bloom patterns. Succession occurs because different species have optimal nutrient uptake at different ambient concentrations and reach their growth peaks at different times. After initiation, the observed bloom developed slowly: over several months both depth-integrated inventories and surface concentrations of chlorophyll a increased only by a factor of ~2 and ~3 respectively.