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Untreated sewage and fertilizer runoff threaten the Florida manatee’s main food source, contributing to malnutrition
Aarin-Conrad Allen, Florida International University
The gentle, slow-moving Florida manatee has no natural predators.
And yet, these charismatic mammals face numerous threats.
Manatees are struck by vessels in busy waterways across the state, and a majority bear scars from these collisions.
Harmful algal blooms – characterized by the rapid growth of algae that degrades water quality – can impair their nervous systems.
With less blubber, or fat, compared with other marine mammals like whales, dolphins, seals and sea lions, manatees are vulnerable to cold-stress syndrome during winter months.
And they can ingest or get entangled in marine debris like derelict fishing gear and drown or be crushed by floodgate and water control structures.
I am a doctoral candidate in marine biology at Florida International University’s Institute of Environment. Over the past 15 years, I have gained extensive experience working with marine mammals, particularly manatees.
Recently, my colleagues at the United States Geological Survey, Florida Department of Environmental Protection and I documented a change in the dietary pattern of manatees. We found that manatees are eating less seagrass – traditionally their primary food source – and more algae than in decades past. This change occurred along Florida’s Atlantic coast during a period of extensive seagrass decline.
We believe this represents an emerging threat to the species’ survival.
Protected species
Manatees were listed as an endangered species under the Endangered Species Act of 1973. By the early 1990s, the manatee population in Florida had dwindled to less than 1,300.
Researchers believe that federal protection, along with additional state measures such as slow-speed zones and no-entry refuges, has contributed to the growth of the manatee population in Florida.
In 2017, manatees were reclassified from endangered to threatened. Surveyors counted 5,733 individual manatees during a statewide aerial survey conducted in 2019.
Florida manatees average 9-12 feet (2.7-3.7 meters) in length and typically weigh about 1,000 pounds (450 kilograms), but they can grow as large as 3,500 pounds (1,600 kilograms). As the largest fully aquatic herbivore, they consume 5% to 10% of their body weight in vegetation each day.
While manatees eat a broad diet of over 60 different plants, they most commonly feed on species of seagrass. Seagrasses are marine plants that, like land plants, have leaves, flowers, roots and seeds, and make their food through photosynthesis.
So what happens when these seagrasses are no longer available?
A changing estuary
The Indian River Lagoon is an estuary along Florida’s east coast that covers roughly 350 square miles (560 square kilometers) between the mainland and barrier islands, from Ponce Inlet to Jupiter Inlet.
It is a critical habitat for manatees, which feed on native seagrass meadows in the lagoon during their seasonal migrations.
Seagrasses are vital to the health of marine ecosystems. They are a habitat for juvenile fish and other marine organisms, provide food for aquatic herbivores, reduce carbon in the atmosphere and improve water quality. They also protect coastal habitats by stabilizing sediments and reducing wave energy that can erode shorelines and damage coastal infrastructure, especially during hurricanes.
For more than a decade, the Indian River Lagoon has experienced extensive loss of seagrass meadows, due to a series of algae blooms associated with nutrient runoff and degraded water quality from septic overflow leaching into the environment.
When untreated sewage and fertilizers flow into the estuary, they add nitrogen, phosphorus and other nutrients that drive excessive algal growth. These harmful algal blooms deplete oxygen levels and block sunlight, which seagrass needs for photosynthesis.
Between 2011 and 2019, over 50% of all seagrass in the lagoon was lost. This led to an increase in macroalgae and even led to a change in the animal communities that live in the lagoon. For example, among finfish, sheepshead populations declined, while seabream numbers increased. Invertebrate communities were also affected, with bryozoans colonizing areas previously dominated by barnacles.
Manatees along the Atlantic coast have suffered two unusual mortality events since the seagrass decline, including one that is ongoing. Researchers attribute the increase in manatee deaths to malnutrition due to a shortage of seagrasses in the Indian River Lagoon.
A shift in manatees’ diet
In our study, we examined 193 manatee stomach samples collected from carcasses recovered from the Indian River Lagoon during two time periods – one before and one after the onset of the seagrass loss in 2011.
We compared stomach sample contents from carcasses collected between 1977 and 1989 with samples collected between 2013 and 2015.
Our findings indicate that manatees consumed 45% less seagrass and 74% more algae after the seagrass decline.
Recently, in a study supported by FIU’s Center for Aquatic Chemistry and Environment, I investigated differences in the nutritional composition – like protein, fat, carbohydrate and fiber – of items identified in manatee stomach samples. My preliminary results show notable differences in the nutritional composition of seagrass and algae.
Marine mammals are particularly vulnerable to dietary shifts due to their large size and high energy demands. Such changes can worsen their physical health and increase the likelihood of starvation.
Depleted oxygen levels are having a similar impact on aquatic vegetation and seagrass meadows in other regions of Florida, like Biscayne Bay and the Caloosahatchee River and Estuary. This suggests that the ecological challenges seen in the Indian River Lagoon could become more widespread.
What is the solution?
Remediation efforts within the lagoon have incorporated the restoration of seagrass through aquaculture and replanting strategies, similar to efforts to restore coral reefs.
While the lagoon’s seagrass has recently shown signs of regrowth, the rehabilitation of the ecosystem must begin with improving and maintaining water quality.
Counties along the lagoon have enacted fertilizer bans that aim to reduce the levels of nitrogen and phosphorus in the water that drive algal blooms.
New research, however, indicates that these restrictions alone will not fix the problem, as residential septic systems are the primary source of nutrient pollution in the lagoon.
Furthermore, many of the factors contributing to harmful algal blooms are intensified by global warming and changing climate, which could accelerate the decline of seagrass in Florida and elsewhere.
Given the multiple, synergistic threats facing manatees, I believe that improving water quality, protecting their food sources, and further research – coupled with community outreach and education – are critical to ensure the long-term survival of this iconic Florida species.
Aarin-Conrad Allen, Ph.D. Candidate in Marine Sciences, Florida International University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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The Long Track Back
Why Downtown Los Angeles Feels Small Compared to Other Cities
Downtown Los Angeles often feels “small” compared to other U.S. cities, but that’s only part of the story. With some of the tallest buildings west of the Mississippi and skyline clusters spread across the region, LA’s downtown reflects the city’s unique polycentric identity—one that, if combined, could form a true mega downtown.
Last Updated on February 18, 2026 by Daily News Staff
Panorama of Los Angeles from Mount Hollywood – California, United States
When people think of major American cities, they often imagine a bustling, concentrated downtown core filled with skyscrapers. New York has Manhattan, Chicago has the Loop, San Francisco has its Financial District. Los Angeles, by contrast, often leaves visitors surprised: “Is this really downtown?”
The answer is yes—and no.
Downtown LA in Context
Compared to other major cities, Downtown Los Angeles (DTLA) is relatively small as a central business district. For much of the 20th century, strict height restrictions capped most buildings under 150 feet, while cities like Chicago and New York were erecting early skyscrapers. LA’s skyline didn’t really begin to climb until the late 1960s.
But history alone doesn’t explain why DTLA feels different. The real story lies in how Los Angeles grew: not as one unified city center, but as a collection of many hubs.
Downtown Los Angeles
A Polycentric City
Los Angeles is famously decentralized. Hollywood developed around the film industry. Century City rose on former studio land as a business hub. Burbank became a studio and aerospace center. Long Beach grew around the port. The Wilshire Corridor filled with office towers and condos.
Unlike other cities where downtown is the place for work, culture, and finance, Los Angeles spread its energy outward. Freeways and car culture made it easy for businesses and residents to operate outside of downtown. The result is a polycentric metropolis, with multiple “downtowns” rather than one dominant core.
A Resident’s Perspective
As someone who lived in Los Angeles for 28 years, I see DTLA differently. While some outsiders describe it as “small,” the reality is that Downtown Los Angeles is still significant. It has some of the tallest buildings west of the Mississippi River, including the Wilshire Grand Center and the U.S. Bank Tower. Over the last two decades, adaptive reuse projects have transformed old office buildings into lofts, while developments like LA Live, Crypto.com Arena, and the Broad Museum have revitalized the area.
In other words, DTLA is large enough—it just plays a different role than downtowns in other American cities.
View of Westwood, Century City, Beverly Hills, and the Wilshire Corridor.
The “Mega Downtown” That Isn’t
A friend once put it to me with a bit of imagination: “If you could magically pick up all of LA’s skyline clusters—Downtown, Century City, Hollywood, the Wilshire Corridor—and drop them together in one spot, you’d have a mega downtown.”
He’s right. Los Angeles doesn’t lack tall buildings or urban energy—it just spreads them out over a vast area, reflecting the city’s unique history, geography, and culture.
A Downtown That Fits Its City
So, is Downtown LA “small”? Compared to Manhattan or Chicago’s Loop, yes. But judged on its own terms, DTLA is a vibrant hub within a much larger, decentralized metropolis. It’s a downtown that reflects Los Angeles itself: sprawling, diverse, and impossible to fit neatly into the mold of other American cities.
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The Knowledge
Century City: From Hollywood Backlot to Business Hub
Century City, originally part of 20th Century Fox’s backlot, transformed into a prominent business district in Los Angeles during the 1950s amid the decline of cinema. Developer William Zeckendorf envisioned a mixed-use urban center, leading to iconic skyscrapers and establishing the area as a hub for law, finance, and media, blending Hollywood history with modern business.
Before Century City became one of Los Angeles’ premier business districts, it was part of 20th Century Fox’s sprawling backlot, used for filming movies and housing studio operations. By the 1950s, as television rose and movie attendance declined, 20th Century Fox faced financial challenges and decided to sell a portion of its land.
Developer William Zeckendorf envisioned a “city within a city”—a modern, mixed-use urban center with office towers, hotels, and entertainment facilities. Branded Century City, the name paid homage to its studio roots while symbolizing LA’s vision for the future.
The first skyscrapers, including the Gateway West Building, set the tone for the district’s sleek, futuristic skyline. Architects like Welton Becket and Minoru Yamasaki helped shape Century City’s iconic look. Over time, it evolved from Hollywood’s backlot to a corporate and legal hub, attracting law firms, financial institutions, and media companies.
Today, Century City stands as a testament to Los Angeles’ postwar optimism, westward expansion, and multi-centered urban growth—a unique blend of Hollywood history and modern business.
Related STM Daily News Links:
- The Evolution of Los Angeles Public Transportation
- Why Los Angeles Grew Into a Sprawling City
- Downtown Los Angeles: Past, Present, and Future
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
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Community
Local governments provide proof that polarization is not inevitable
Local politics help mitigate national polarization by focusing on concrete issues like infrastructure and community needs rather than divisive symbolic debates. A survey indicates that local officials experience less partisanship, as interpersonal connections foster recognition of shared interests. This suggests that reducing polarization is possible through collaboration and changes in election laws.
Lauren Hall, Rochester Institute of Technology
When it comes to national politics, Americans are fiercely divided across a range of issues, including gun control, election security and vaccines. It’s not new for Republicans and Democrats to be at odds over issues, but things have reached a point where even the idea of compromising appears to be anathema, making it more difficult to solve thorny problems.
But things are much less heated at the local level. A survey of more than 1,400 local officials by the Carnegie Corporation and CivicPulse found that local governments are “largely insulated from the harshest effects of polarization.” Communities with fewer than 50,000 residents proved especially resilient to partisan dysfunction.
Why this difference? As a political scientist, I believe that lessons from the local level not only open a window onto how polarization works but also the dynamics and tools that can help reduce it.
Problems are more concrete
Local governments deal with concrete issues – sometimes literally, when it comes to paving roads and fixing potholes. In general, cities and counties handle day-to-day functions, such as garbage pickup, running schools and enforcing zoning rules. Addressing tangible needs keeps local leaders’ attention fixed on specific problems that call out for specific solutions, not lengthy ideological debates.
By contrast, a lot of national political conflict in the U.S. involves symbolic issues, such as debates about identity and values on topics such as race, abortion and transgender rights. These battles are often divisive, even more so than purely ideological disagreements, because they can activate tribal differences and prove more resistant to compromise.
Such arguments at the national level, or on social media, can lead to wildly inaccurate stereotypes about people with opposing views. Today’s partisans often perceive their opponents as far more extreme than they actually are, or they may stereotype them – imagining that all Republicans are wealthy, evangelical culture warriors, for instance, or conversely being convinced that all Democrats are radical urban activists. In terms of ideology, the median members of both parties, in fact, look similar.
These kinds of misperceptions can fuel hostility.
Local officials, however, live among the human beings they represent, whose complexity defies caricature. Living and interacting in the same communities leads to greater recognition of shared interests and values, according to the Carnegie/CivicPulse survey.
Meaningful interaction with others, including partisans of the opposing party, reduces prejudice about them. Local government provides a natural space where identities overlap.
People are complicated
In national U.S. politics today, large groups of individuals are divided not only by party but a variety of other factors, including race, religion, geography and social networks. When these differences align with ideology, political disagreement can feel like an existential threat.
Such differences are not always as pronounced at the local level. A neighbor who disagrees about property taxes could be the coach of your child’s soccer team. Your fellow school board member might share your concerns about curriculum but vote differently in presidential elections.
These cross-cutting connections remind us that political opponents are not a monolithic enemy but complex individuals. When people discover they have commonalities outside of politics with others holding opposing views, polarization can decrease significantly.
Finally, most local elections are technically nonpartisan. Keeping party labels off ballots allows voters to judge candidates as individuals and not merely as Republicans or Democrats.
National implications
None of this means local politics are utopian.
Like water, polarization tends to run downhill, from the national level to local contests, particularly in major cities where candidates for mayor and other office are more likely to run as partisans. Local governments also see culture war debates, notably in the area of public school instruction.
Nevertheless, the relative partisan calm of local governance suggests that polarization is not inevitable. It emerges from specific conditions that can be altered.
Polarization might be reduced by creating more opportunities for cross-partisan collaboration around concrete problems. Philanthropists and even states might invest in local journalism that covers pragmatic governance rather than partisan conflict. More cities and counties could adopt changes in election law that would de-emphasize party labels where they add little information for voters.
Aside from structural changes, individual Americans can strive to recognize that their neighbors are not the cardboard cutouts they might imagine when thinking about “the other side.” Instead, Americans can recognize that even political opponents are navigating similar landscapes of community, personal challenges and time constraints, with often similar desires to see their roads paved and their children well educated.
The conditions shaping our interactions matter enormously. If conditions change, perhaps less partisan rancor will be the result.
Lauren Hall, Associate professor of Political Science, Rochester Institute of Technology
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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