NSEMA Stakeholders and other interested parties

There has been concern about the die-off of sponges and tunicates in Matlache Pass.   Here is an explanation from Tom Fraser at the Mote Marine Laboratory:

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From: Tom Fraser <tfraser15@comcast.net>
Date: February 8, 2010 11:55:20 AM EST
To: tjanicki@janickienvironmental.com
Cc: hzarbock@janickienvironmental.com
Subject: Life & Death in Estuaries

Hi Tony,

At your request through Hans Zarbock, I offer these observations about the influence of physical conditions on sessile benthic invertebrates in the greater Charlotte Harbor estuary.

Many sessile benthic invertebrates found near the higher salinity range in the greater Charlotte Harbor estuary can be vulnerable to significant physical changes (salinity, dissolved oxygen, water color). Several years of drought conditions shift the potential range of habits toward headwaters (freshwater inflow) by increasing salinity, less frequency of stratified conditions and less color in the water. The life histories of these animals usually include planktonic larval stages as part of their strategy to find suitable habitats to settle and grow to adults. Opening of 'new' habitats by virtue of higher salinities resulting from climatic conditions may lead to longer periods of colonization, even if usually seasonally temporary. These animals will out compete those species that require lower salinities and may be accustom to lower dissolved oxygen and higher water color. When followed by a very wet year (or wetter years), a die-off of sessile benthic invertebrates will occur when chronic or acute duration of conditions result in lower salinities, longer periods of stratification, lower dissolved oxygen and higher water color. The 'new' habitat will be colonized by fewer species that live best in these harsher conditions.

Such changes are the nature of dynamic estuaries.

Cheers,

Tom

Thomas H. Fraser, PhD
Adjunct Scientist
Mote Marine Laboratory
22602 Adorn Avenue
Port Charlotte, Florida 33952
Telephone 941-626-6995