Spring Bloom - Spring Bloom Variability and The Influence of Climate Change

Spring Bloom Variability and The Influence of Climate Change

Variability in the patterns (e.g. timing of onset, duration, magnitude, position, and spatial extent) of annual spring bloom events has been well documented. These variations occur due to fluctuations in environmental conditions, such as wind intensity, temperature, freshwater input, and light. Consequently, spring bloom patterns are likely sensitive to global climate change.

Links have been found between temperature and spring bloom patterns. For example, several studies have reported the earlier onset of the spring bloom to be correlated with temperature increases over time. Furthermore, in Long Island Sound and the Gulf of Maine, blooms begin later in the year, are more productive, and last longer during colder years, while years that are warmer exhibit earlier, shorter blooms of greater magnitude.

Temperature may also regulate bloom sizes. In Narragansett Bay, Rhode Island, a study by Durbin et al. (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. Oviatt et al. (2002) 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.

Miller and Harding (2007) suggested climate change (influencing winter weather patterns and freshwater influxes) was responsible for shifts in spring bloom patterns in the Chesapeake Bay. They found that during warm, wet years (as opposed to cool, dry years) the spatial extent of blooms were larger and were positioned more seaward. Also, during these same years, biomass was higher and peak biomass occurred later in the spring.