Besides killing fish, red tide can cause respiratory irritation in humans and other mammals. Red tide, caused by Karenia brevis, crept its way to Lee County after festering off Sarasota County for several weeks."Some (fish) have been missing their eyes for a while, but you can smell the red tide and cell counts are elevated," said Rick Bartleson, a water quality scientist at the Sanibel-Captiva Conservation Foundation. "The fish probably didn't wash from a distance away. It was most likely pretty close to Sanibel or right at Sanibel." Florida Fish and Wildlife officers say the fish kill is caused by red tide. The toxic bloom kills fish and causes coughing, sneezing and other respiratory problems for people, every year. Beachgoers looking to enjoy a nice night on the sand on Wednesday, were surprised at what they found. "We can't see the water, see the color but we did see some smaller dead fish on the beach and that's something I usually don't see here," said Erin Neitzrlt. Wildlife officers released a new map which shows red tide blooms off the Southwest Florida coast. The white, yellow, and orange dots off Charlotte, Lee, and Collier Counties represent low to medium red tide levels. Early Thursday morning, city crews were out with rakes and buckets cleaning up the dead fish. Recent counts along Sanibel and in Pine Island Sound measured 500,000 to 760,000 cells per liter. It takes about 10,000 cells per liter to start killing fish and be visible from outer space. Tourists from Toronto, Vermont and Germany alike stepped over piles of dead fish to enjoy the waters of Sanibel. Geraldine Christie and her husband Sean had traveled from Indianapolis. They got out of their car and it hit them. "I smelled something funky," she said. "I figured it was the ocean." Most tourists chock it up to nature, but the smell and sight are unavoidable for those who shelled out the cash to come to sunny Florida in the winter. Ray Tiberia and Sara Caracciolo, both 34, from Albany, New York, were glad they had a flashlight Wednesday night. Otherwise, they would have stepped right into "just piles and piles" of fish, she said. Sporting a sunburn and toting a Bud Light on Thursday morning, Tiberia said the fish haven't ruined their vacation. Still, Caracciolo admitted: "It smells a little bit." The organism occurs naturally in this part of the Gulf of Mexico but can be fed by excessive nutrients running off the Southwest Florida landscape. The nutrients don't cause Karenia brevis to form but can extend the frequency and duration of the harmful algal blooms, which give off a neurotoxin. "They (red tide numbers) went down last week," said Bartleson. "On Monday, I found medium concentrations along the causeway, and that's bad. Then numbers started shooting up along the beaches Wednesday." Seafood served commercially must past state tests designed to trace the neurotoxin, so it is safe to buy some fillets at the grocery or have a grouper sandwich. Scientists don't know how long the bloom will brew in the region. Conditions can improve in a matter of days or last several months. "Sometimes a red tide can wash by (the Lee County area) and keep going," Bartleson said. "But once it gets into (Pine Island) sound it can take off and linger." But red tide affects more than sea life.