Posted by: The ocean update | November 11, 2015

The sound of silence : underwater recordings reveal impact of red tide in Tampa Bay (Florida, USA)

The red tide outbreak in 2005 was so intense that it could be seen from the air, stretching from Key West north to Pasco County. Along with the visible victims that washed ashore, scientists and sportsmen report severe damage to both soft- and hard-bottom reefs offshore from Tarpon Springs to Sarasota. It appears that a layer of cooler water trapped the K. brevis cells on the bottom, killing benthic creatures including sponges, corals, worms, mollusks, crabs, sea urchins and starfish. A similar, but smaller, reef die-off occurred in the summer of 1971. FWRI researchers tracking that event reported that recolonization of reef fishes was seemingly complete within 18 to 24 months and that fish species composition was basically identical five years later.

The red tide outbreak in 2005 was so intense that it could be seen from the air, stretching from Key West north to Pasco County.

November 11th, 2015. The sound of silence can be very revealing.

A study of underwater sound that Eckerd scientists collected during a severe red tide outbreak around Tampa Bay 10 years ago uncovered the first evidence of the impact of algal blooms on snapping shrimp.

The study, published in September in Royal Society Open Science, was the senior thesis of Eckerd biology student Kate Indeck ‘13, now a Ph.D. student at the University of Queensland in Australia.

The work grew out of the long-running Eckerd College Dolphin Research Project led by Associate Marine Science and Biology Professor Shannon Gowans.

The PBS Newshour series Science Wednesday featured the study this week in a report headlined 7 sounds in nature that humans rarely hear.

Spectrograms showing ambient noise for midnight August 15 (a) 2005 (severe HAB) and (b) 2006 (no severe HAB), 0–5000 Hz to show detail of fish sound. Approximate bandwidth of sounds from snapping shrimp, silver perch and spotted seatrout shown on 2006 spectrogram. Note some spotted seatrout and snapping shrimp present in 2005. Spectrograms are 512 point with a 50% overlap Hamming window.

Spectrograms showing ambient noise for midnight August 15 (a) 2005 (severe HAB) and (b) 2006 (no severe HAB), 0–5000 Hz to show detail of fish sound. Approximate bandwidth of sounds from snapping shrimp, silver perch and spotted seatrout shown on 2006 spectrogram. Note some spotted seatrout and snapping shrimp present in 2005. Spectrograms are 512 point with a 50% overlap Hamming window.

Citation : A severe red tide (Tampa Bay, 2005) causes an anomalous decrease in biological sound. Katherine L. Indeck, Peter Simard, Shannon Gowans, Susan Lowerre-Barbieri, David A. Mann. R. Soc. open sci. 2015 2 150337; DOI: 10.1098/rsos.150337. Published 16 September 2015

NB : The red tide outbreak in 2005 was so intense that it could be seen from the air, stretching from Key West north to Pasco County. Along with the visible victims that washed ashore, scientists and sportsmen report severe damage to both soft- and hard-bottom reefs offshore from Tarpon Springs to Sarasota. It appears that a layer of cooler water trapped the K. brevis cells on the bottom, killing benthic creatures including sponges, corals, worms, mollusks, crabs, sea urchins and starfish. A similar, but smaller, reef die-off occurred in the summer of 1971. FWRI researchers tracking that event reported that recolonization of reef fishes was seemingly complete within 18 to 24 months and that fish species composition was basically identical five years later.

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