d="par0005">We studied cyanobacteria dynamics in the Pontchartrain Estuary during two years.
dd><dt class="label">•dt><dd>d="par0010">Cyanobacteria abundance was greatest during N-limited conditions in summer.
dd><dt class="label">•dt><dd>d="par0015">No difference in summer cyanobacteria between diversion year and non-diversion year.
dd><dt class="label">•dt><dd>d="par0020">Microcystin concentrations were not correlated to cyanobacteria abundance.
dd><dt class="label">•dt><dd>d="par0025">DIN uptake by non-harmful algae reduced export to coastal ocean during diversion.
dd>dl>