The persistence, extent, and severity of hypoxia through peak summer
months can also vary. The layers of a stratified water column can mix
due to high winds and rough choppy waters. For instance, hypoxia is
typically less severe during and immediately after storm events. However,
hypoxic masses return their pre-storm extent after winds subside (Rabalais
et al. 1999). In addition, strong shoreward winds, as well as upwelling
of oxygen rich water masses from deeper waters can push masses of hypoxia
into shallow inshore areas (Breitburg 1990;
Rabalais et al. 2002). Often, stressed
aquatic organisms are forced along with the hypoxia mass into shallow
waters. For fishermen, this occurrence is known as a “jubilee,”
as the stunned shrimp, crabs, and fish become easily harvestable in
shallow depths. When the organisms forced onshore are already dead due
to extreme hypoxia, the event is known as a jubilee “gone bad”
(Rabalais et al. 2002). Droughts and floods can also influence hypoxia.
When a drought occurs, the input of freshwater is significantly decreased,
resulting in significantly weaker density stratification. During droughts,
hypoxia is typically minor to completely absent (Rabalais et al. 1999).
In contrast, floods generate increased freshwater and nutrient input
to saline waters, resulting in greater stratification and eutrophication,
and in turn, increased hypoxia.