pseudo-nitzschia is the group of organisms that is most commonly responsible for red tides off california.
pseudo-nitzschia is the group of organisms that is most commonly responsible for red tides off california.
which group of organisms is most commonly responsible for red tides off california?
pseudo-nitzschia
an algal bloom is a rapid increase or accumulation in the population of algae (typically microscopic) in an aquatic system. algal blooms may occur in freshwater as well as marine environments. freshwater algal blooms are the result of an excess of nutrients, particularly some phosphates. harmful algal blooms are algal bloom events involving toxic or otherwise harmful phytoplankton such as dinoflagellates of the genus "alexandrium" and "karenia" or diatoms of the genus "pseudo-nitzschia". is an algal bloom that causes negative impacts to other organisms via production of natural toxins, mechanical damage to other organisms, or by other means. habs are often associated with large-scale marine mortality events and have been associated with various types of shellfish poisonings. such blooms often take on a red or brown hue and are known colloquially as red tides. it is unclear what causes habs; their occurrence in some locations appears to be entirely natural, while in others they appear to be a result of human activities.
harmful algal bloom and hypoxia research and control amendments act of 2013
many mixotrophic and some heterotrophic dinoflagellates are known to cause red tides or harmful blooms that result in large-scale mortality of fish and shellfish. studies on red tides have been conducted to determine the mechanism of outbreak and the persistence of red tides caused by mixotrophic dinoflagellates such as "karenia brevis", "prorocentrum donghaiense" and "prorocentrum minimum" in low nutrient concentration waters. in the case of serial red tides, one mixotrophic dinoflagellate species is dominated by another mixotrophic species in rapid succession over a short span of days. a possible explanation for the occurrence of different dominant mixotrophic dinoflagellates during serial red tides is the ability of mixotrophic dinoflagellates to feed on both heterotrophic bacteria and cyanobacteria (such as "synecchococcus") spp., which provide limiting nutrients such as phosphorus, and nitrogen simultaneously. it is proposed that during serial red tides, feeding by larger mixotrophic dinoflagellates on smaller species may be a driving force for the succession of dominant species. nitrogen and phosphorus is taken up by direct transfer of the materials and energy between the mixotrophic dinoflagellates; therefore, nutrient supply does not rely on the release of nitrogen and phosphorus by other organisms. hence, mixotrophy can cause uncoupling between nutrient concentrations and the abundance of mixotrophic dinoflagellates in natural environments.
mixotrophic dinoflagellate