More than a thousand people from across the Treasure Coast showed up to a Stuart rally for Democratic gubernatorial candidate Andrew Gillum on Sunday, shocking event organizers and local Democrats.

Gillum, who spent the morning participating in a boat tour with local scientists and environmentalists and Democratic candidate for Congress Lauren Baer, spoke to rally attendees about blue-green algae and red tide, health care, Justice Brett Kavanaugh's nomination to the Supreme Court and several other policy topics.

Rally organizers and the Gillum campaign expected somewhere between 100 and 200 people to attend the rally at Memorial Park, Gillum told TCPalm. When they arrived, they spotted a sea of people.

"I was on the stage looking back as far as I can see," Gillum said. "I was absolutely blown away."

Several other Democratic candidates, including Baer and candidates in state legislative races, also spoke at the event.

Algae and Red Tide

During the tour of the St. Lucie River, scientists discussed the causes of algae blooms and the worst affected areas, and Gillum lamented cuts to the Department of Environmental Protection.

Gillum said he has experience pushing for environmentally-friendly projects while serving as mayor, and earlier a city commissioner, in Tallahassee.

Tallahassee has pushed for septic to sewer conversions in older neighborhoods to prevent nitrate pollution in Wakulla Springs just south of the city. They've also pushed for solar energy grids.

Gillum said to combat blooms he'd look at the source of the problem - pollution from agriculture and communities north of Lake Okeechobee. He also supports more projects to restore the natural flow of water from the Kissimmee River watershed south to Lake Okeechobee, eventually moving into the Everglades and Florida Bay.

More: Andrew Gillum: Algae and other environmental problems need science-based solutions

Sugar

In the crowd, a few anti-sugar industry signs were spotted.

Gillum has criticized the industry's leaders for having too much influence over policy in Tallahassee, but doesn't often reference Florida's largest sugar companies, Clewiston-based U.S. Sugar and West Palm Beach-based Florida Crystals.

Gillum said while looking for environmental solutions, people must look for solutions to make sure those who rely on the sugar industry for their livelihood can still survive economically.

He called for a "new deal" for people who grow and harvest sugar south of the lake that would include technical and on-the-job training. He said the companies which benefit from land deals from the state have not done enough for people who lose their jobs as a result of environmental advocacy.

"My job is not to destroy any industry, but to make those industries better. It's not to destroy anybody's livelihoods, but to make sure they get access to the training and the support that they need," Gillum said.

"We're going to hold big polluters accountable for their contribution to this environmental degradation."

Appealing to GOP voters

Gillum faces former Republican Congressman Ron DeSantis in the November election.

DeSantis has portrayed himself as more environmentally-friendly than Scott during the campaign, but has declined to criticize the Republican governor for the cuts to DEP and local water management districts.

Martin County is solidly Republican: 62 percent of voters supported Donald Trump in 2016.

Gillum said his campaign is looking at traveling to Republican areas because some voters may be able to side with him on some issues, and choose to back a Democrat instead. He pointed to large crowds in Palm Coast and Palatka as other examples of successful events in conservative areas.

Gillum said Treasure Coast voters should see past DeSantis' comments about algae, and look at his environmental record in Congress.

More: Andrew Gillum, Ron DeSantis: Environmental records differ on climate change, algae blooms

Gillum pointed out DeSantis was an obstructionist in Congress, supporting a government shutdown during the Obama Administration.

"He may speak one tune while he's out on the trail, but I think people have to measure him by his actions.

"They're not there for no reason. They are the same people who have stood in the way of strong environmental protection throughout the length of the Scott Administration."

Gillum said he understood that reliably Republican voters might not agree with him on other issues. But he hoped that they would look into supporting him over his opponent because of his environmental platform.

"Maybe they can't agree with me on everything. But one thing we ought to be able to agree on is that we owe it to our environment. The government is supposed to do the bidding of the people of the state, not of special interests and not the biggest polluters in the state."