Single-celled algae that grow into transient, miles-wide expanses are prominent players in oceanic food webs. But tinier organisms—viruses lethal to these algae— can take down massive algal blooms just as quickly, according to results published today (August 21) in Current Biology.
Marine algal blooms have complex life cycles; sunlight and wind are as crucial to their growth as nutrients and the presence of predators, like zooplankton. Although researchers have previously studied the factors that cause blooms to begin, the physical and biological factors that cause their death were not as clear.
Cloud physicist Ilan Koren and marine microbiologist Assaf Vardi, both of the Weizmann Institute of Science in Israel, teamed up with their colleagues to address the question.
The team combined satellite data with in situ measurements of water samples taken during a month-long summer 2012 cruise in the North Atlantic to quantify the growth, life, and death of an approximately 30-kilometer (18.6-mile)-wide bloom of Emiliana huxleyi, one of the most abundant marine algae. The patterns they observed mimicked their previous experimental studies. “We didn’t expect to see such a clear, sharp signature in nature that resembled what we had measured in the lab,” said Vardi.
The oceanic patch, identified from satellite data based on its high chlorophyll concentration, was embedded within a well-stratified column of water that didn’t mix much with its surroundings. Over a 25-day life cycle, the patch began with a fast growth phase, increasing its chlorophyll concentration four-fold in just 17 days. Approximately eight days after reaching its peak, contrasting chlorophyll faded into the background, indicating the bloom’s demise.
Single-celled algae that grow into transient, miles-wide expanses are prominent players in oceanic food webs. But tinier organisms—viruses lethal to these algae— can take down massive algal blooms just as quickly, according to results published today (August 21) in Current Biology.
Marine algal blooms have complex life cycles; sunlight and wind are as crucial to their growth as nutrients and the presence of predators, like zooplankton. Although researchers have previously studied the factors that cause blooms to begin, the physical and biological factors that cause their death were not as clear.
Cloud physicist Ilan Koren and marine microbiologist Assaf Vardi, both of the Weizmann Institute of Science in Israel, teamed up with their colleagues to address the question.
The team combined satellite data with in situ measurements of water samples taken during a month-long summer 2012 cruise in the North Atlantic to quantify the growth, life, and death of an approximately 30-kilometer (18.6-mile)-wide bloom of Emiliana huxleyi, one of the most abundant marine algae. The patterns they observed mimicked their previous experimental studies. “We didn’t expect to see such a clear, sharp signature in nature that resembled what we had measured in the lab,” said Vardi.
The oceanic patch, identified from satellite data based on its high chlorophyll concentration, was embedded within a well-stratified column of water that didn’t mix much with its surroundings. Over a 25-day life cycle, the patch began with a fast growth phase, increasing its chlorophyll concentration four-fold in just 17 days. Approximately eight days after reaching its peak, contrasting chlorophyll faded into the background, indicating the bloom’s demise.
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