LTC 234-2020 Update on the Sargassum SeaweedDocuSign Envelope ID: 2A31 DDEF-3D0C-4F9A-843A-6564981800D0
AAAMIBEACH
City of Miami Beach, 1700 Convention Center Drive, Miami Beach FL 33139
LTC# 234-2020 LETTER TO COMMISSION
TO: Mayor Dan Gelber and Members of the City Commission
FROM: Jimmy L. Morales, City Manager
DATE: July 2, 2020
SUBJECT: UPDATE ON THE SARGASSUM SEAWEED
The purpose of this Letter to Commission is to provide the Mayor and City Commission with an
update on the removal efforts of the sargassum seaweed.
Sargassum seaweed is a natural occurring alga found in the marine environment. It typically floats
on the surface of the open ocean and is carried close to the shore by currents where it is deposited
along the shoreline throughout both, incoming and out-going tides. The amount of seaweed which
accumulates on our beaches varies seasonally, with greater proliferation observed from late
spring thorough the early months of autumn. The preponderance of seaweed during this period
has continued to increase over the last few years. Over the past three years the City of Miami
Beach, our neighboring communities and nations throughout the entire Caribbean basin have
experienced much larger accumulations of seaweed than we have in prior years. It should be
noted that Sargassum is not a neurotoxin, while it does cause a sulfur-like smell that can be
unpleasant it is not a health concern.
The amount of seaweed we receive is dependent on number of factors including availability of
nutrients in the water, water temperatures, carbon dioxide concentration in the air, wind direction,
and ocean currents.
The City's beaches are owned by the State of Florida and fall under several jurisdictions. Miami-
Dade County is responsible for the beaches' maintenance whereas the City is responsible for
managing activities that occur on the beach. Beach management is a collaborative effort. As it
relates to seaweed, Miami-Dade County Beach Operations and Maintenance is tasked with
cleaning and grooming the shoreline as well as turning the accumulated seaweed into the sand
to minimize visibility and odor. Turning the seaweed with sand and into the shoreline helps reduce
sand erosion and further, preserves the ecology which provides food for shorebird communities
and nutrients for healthy dunes.
Our sargassum seaweed season typically begins in April or May and runs through September or
October. The accumulation of seaweed last year led to discussion between the City of Miami
Beach and Miami Dade County on the need for an outside contractor to assist Miami-Dade
County with their beach cleaning efforts. The first phase of this included identifying "hotspot s".
These "hotspots" identified the locations where the greatest amounts of seaweed accumulated.
The larger the accumulation the more difficult it is to groom the shoreline and remove the
seaweed.
DocuSign Envelope ID: 2A31 DDEF-3D0C-4F9A-843A-6564981800D0
L TC: Sargassum Seaweed Removal Efforts
The locations which were identified were the southernmost point of Miami Beach, also known as
South Pointe. This is the area which lies between the rock jetty and the jetty lifeguard tower.
The second location identified was between 26th Street and 32nd Street on both the North side
and South side of the rock breakwaters in that area. There are three sets of rock breakwaters
between 26" Street and 32"° Street. Depending on wind direction, the seaweed accumulations
occur on either the South as a result of Southeast winds or on the North side of the rock groins
with Northeast winds. Although these locations were identified as the areas of the greatest
accumulations of seaweed, we realize that seaweed accumulates along the entire 7 miles of
Miami Beach's shoreline.
Since August 2019, Beach Raker, a well-known beach grooming company has been providing
seaweed removal services seven days per week to address hotspot areas, including areas from
26" Street to 32nd Street. Additionally, they provide beach grooming from the Government Cut
to the Jetty seven days a week from May 1 through November 30 and during the low season
(February to April 30), they render services four times per week (Wednesday, Friday, Saturday,
and Sunday). While the contractor is providing seaweed removal services, Miami-Dade County
continues to provide shoreline bleeding with two tractors seven days per week. These tractors do
not remove for hauling purposes and a seaweed. They travel the water line and mix seaweed with
sand so that the seaweed is buried along the waterline. This is the environmentally preferable
method to groom our beaches. The buried seaweed tends to sink in the sand, does not give off
an odor, and adds to and increases protection against erosion. This method is also the most cost-
effective method to managing sargassum.
Miami-Dade County's contract with Beach Raker provides service to two large areas of Miami
Beach and one area in Bal Harbour. The contract is just under $2 million per year. During the
month of May 2020, Beach Raker collected and hauled away 670 yd.3 of seaweed. During the
month of June 2020 estimates are indicating that 4000 to 4200 yd.3 of seaweed will be removed
from these areas.
Seaweed accumulates during both incoming and outgoing tides, causing large bands of
seaweed along the shoreline. Just as seaweed is removed or turned into the shoreline through,
there is seaweed floating in the water that will begin to accumulate as the tides change.
Unfortunately, due to environmental regulations seaweed cannot be removed from the water.
West winds keep the seaweed offshore and away from the shoreline for some period of time,
however during the late spring and summer months the winds typically blow in from the east
further exacerbating the problem.
Sargassum has a high nutrient content that can be used for as fertilizer. In order to reduce
waste going to the landfill, Beach Raker has partnered with local nurseries to provide at no cost
the seaweed to be used as fertilizer.
The City of Miami Beach Property Management Department will continue to work alongside the
Miami-Dade County Beach Operations team to "blade" and remove seaweed from the "hotspots"
during the high season of sargassum seaweed. The City is also coordinating with researchers at
the University of Miami Rosenstiel School of Marine and Atmospheric Science to better forecast
periods of high sargassum.
Should you have any questions, please feel free to contact Adrian Morales at 305-673-7631.
DocuSign Envelope ID: 2A31 DDEF-3D0C-4F9A-843A-6564981800D0
L TC: Sargassum Seaweed Removal Efforts
(Photos)
D o c u S ig n E n v e lo p e ID : 2 A 3 1D D EF -3D 0 C -4F 9 A -8 4 3 A -6 5 6 4 9 8 18 0 0 D 0
L TC: Sargassum Seaweed Removal Efforts
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