[USA] Maine environmental officials, scientists and coastal municipal leaders all recognize an ecological shift has been happening along southern coastal beaches and inlets in recent years that has allowed for periodic but massive influxes of seaweed to wash ashore. Smelly, unsightly and not conducive to a tourist economy, this seaweed invasion has people searching for reasons and working to bridge solutions.
From Biddeford Pool to York this summer, seaweed often several feet thick clogged beaches, following a trend that began last year when a huge swath of seaweed washed up on Long Sands Beach in York in August.
“This is something no one has seen before” in Maine, said Keri Kaczor, coordinator of the Maine Healthy Beaches program. While after large summer rainfall events, beach testing will typically show various pollutants that washed ashore, this summer has been relatively dry, she said. More and more, she said, high bacteria counts in the past few months can be traced directly to loose seaweed on the beach.
“Seaweed is the first thing we look for,” she said. Its presence troubles her.
“What we think is happening is that there’s a larger shift occurring in the ecosystem as a whole. This is indicative of coastal imbalance,” she said.
Seaweed, or macroalgae, naturally grows off Maine’s shores. While there are more than 250 species found in the Gulf of Maine, about a dozen different native species are common along the coast. These include Ascophyllum, or rockweed, the skinny seaweed scattered with bubble-like protrusions; Fucus vesiculosus, or bladderwrack; Saccharina latissima, or sugar kelp; and ulva lactuca, or sea lettuce.
Seaweed grows just off the coast and is lightly attached to rocks and even gravel, “so when there’s any turbidity at all – and it doesn’t take a serious storm – it’s torn from its roots and washed ashore,” said Susan Brawley, professor of marine sciences at the University of Maine who specializes in marine algae.
In recent years, these native species have been mixing with at least one newcomer – Heterosiphonia japonica, a red species of seaweed that has been found in France, Norway and along the Rhode Island coast, said James Coyer, a Cornell University marine scientist who works at the Shoals Marine Laboratory on Appledore Island. The seaweed made its first appearance on Appledore in 2011 and has been abundant since. As a scientist, Coyer cautions drawing broad conclusions from the introduction of this species on the coast of Maine.
“The first thing one thinks of when a massive invasion occurs is a change in the abiotic or biotic environment that allows it to prosper.” But he said, “the success and demise of invaders is difficult to understand and certainly difficult to predict.”
The problem is that all of these seaweeds are growing in number, creating more algae that wash ashore. According to Brawley, algae need three conditions to grow – nutrients, light and temperature.
Although she said definitive studies have yet to be conducted on increasing seaweed along the Maine coast, “it is clear that warming ocean temperatures in the Gulf of Maine play a factor.”
Algae increases when the water gets warmer. Add to this the likelihood of pollutants being added to the ecosystem, said Brawley.
She said stormwater outfall from sewage treatment plants, failing septic systems near shore, and non-point source pollution like fertilizer runoff from lawns can add to the soup “soaked up by algae closest to the land.”
She points to algae inundations along the coasts of China and France in recent years that have swamped coastal communities, and algae blooms along the Rhode Island coast.
Coyer said rising ocean temperatures and pollution might be factors, but said much more study needs to be done. “The reasons are likely to be much more complex and interactive,” he said. “I hate to sound like a ‘cop out,’ but numerous other hypotheses need to be considered and evaluated before we can fully understand this dramatic increase.”
In the best of worlds, what the ocean brings in, it would bring out again in time. However, the perfect time for seaweed invasions is summer tourist season. Beach managers are grappling with how to deal with the nuisance and keep their visitors happy.
“I have a group of unhappy beachgoers whenever this happens,” said Wells Town Manager Jonathan Carter. “They don’t understand why we aren’t on the beaches, cleaning it up. Yes, we want clean beaches, but we need to do it in a way that is safe and prudent.”
Wells and York were among communities hit by seaweed a foot or more thick earlier this summer. Nearly all the beaches along the southern coast are in the coastal dune system – even if the dunes no longer exist, as in Long Sands Beach in York where Long Beach Avenue was built over the dune 50 years ago.
The Maine Department of Environmental Protection says communities can move the seaweed but can’t remove it except by permit. Mike Mullen of the DEP said some communities have been given permits to remove seaweed, compost it and bring it back to add to the vegetative system of sand dunes. However, he admits the DEP needs to review its permitting process given the recent invasions of the algae.
“I think it’s clear this is something we’re going to have to look at a little more closely,” he said.
He added any change in sand dune rules would require vetting from the DEP and Legislature. It is not something the DEP would do lightly, he said, “but this is potentially not just an anomaly and is going to be a frequent occurrence.”
In the meantime, said Mullen, DEP will work with towns facing an inundation to look for tailored, limited solutions.
The situation is many layered and likely here to stay, said Kaczor of Maine Healthy Beaches.
“When seemingly excessive mounds of seaweed cover valued coastal beaches during Maine’s short summer season, there are crucial factors to consider in mapping the course of action: water quality, public health, aesthetics, tourist economies, ecosystem health and the laws that are made to preserve the integrity of these environments,” she said.
Photo: Clusters of seaweed on Harbor Beach in York, Maine. Southern coastal beaches in Maine dealt with a rising amount of seaweed this summer. Too much seaweed can reduce usable beach area and cause odor. Photo by Rich Beauchesne/Seacoastonline
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