World Seagrass Day

Seagrasses are plants, and as such need carbon dioxide, water, and sunlight to produce their own food (carbohydrates = sugar) and oxygen through the process called photosynthesis. To grow, they also need ample nutrients (nitrogen/phosphorus) and stable sediments. Most importantly, seagrasses need clear water to receive enough light to photosynthesize. Although oxygen is produced during photosynthesis, they also require oxygenated bottomwaters and can be affected by anoxic events (depletion of oxygen). Seagrasses tend to prefer sheltered environments such as shallow bays, lagoons, and estuaries (where rivers flow into the sea) to thrive, but each seagrass species needs the right recipe of conditions to survive and grow. Chloroplasts within the seagrass blades convert carbon dioxide and water into carbohydrates (sugar) and oxygen via photosynthesis . Seagrass belowground structures (roots and rhizomes) absorb and store nutrients, in addition to anchoring the plant within the sediments

Seagrasses are impacted by human disturbances such as dredging, coastal development, and boating activities including mooring, anchoring, running aground, and propeller scarring. Other disturbances like runoff from rivers can reduce water clarity because of increased nutrient pollution and suspended sediments entering our estuaries. Excess nutrient loads can fuel the growth of algal blooms that block light from reaching seagrasses. Climatic disturbances including regional droughts , hurricanes and sea level rise can also affect seagrasses by changing the water conditions. Abnormally low precipitation and the timing of droughts (i.e., summer) can increase salinity and water temperatures and reduce oxygen solubility ; no oxygenation within the sediments allows the buildup of sulfides which is toxic to seagrasses. Hurricanes and tropical storms increase river discharge and runoff, reducing salinities and oxygen and dumping excess nutrients in receiving water bodies. Sea level rise...

As seagrass scientists, it’s our job to provide outreach and education to the public about the importance of this valuable marine ecosystem . But ultimately, it starts with you!  The easiest way to protect seagrasses is by preventing damage in the first place.  Responsible boating practices not only can save the life of your passengers, but also seagrasses. Propeller scarring is an important cause of damage to seagrass beds. When a boat’s propeller cuts through the seagrass, it fragments the bed and is detrimental to its growth and to the numerous organisms that rely on it for food, shelter, and protection. It can take months or even years to fully recover.   Regulations can now hold boaters accountable on a state and federal level for costs related to assessing damage, restoring habitat, and long-term monitoring of the restored area. In addition, if you are a coastal property owner, work in a coastal town or just happen to love manatees there are other important th...

Climate change is affecting ecosystems around the world, including seagrasses. The combustion of fossil fuels since the Industrial Revolution has increased the atmospheric carbon dioxide (CO2) concentration, increasing the greenhouse effect by trapping more solar heat near the earth’s surface. Seagrasses and other marine creatures residing at the edge of their distributional range are vulnerable to the effects of rising ocean temperatures. Warmer water temperatures can cause changes in physiology (i.e., metabolic rates), behavior (i.e., increased grazing effort), resulting in altered population dynamics, susceptibility to disease, food and oxygen requirements and range shifts, all of which can alter biodiversity and ecosystem function. For example, “ tropicalization ” occurs as tropical species extend their range into temperate regions, altering foodwebs, introducing new diseases and parasites and potentially destabilizing temperate species populations. With the increase in atmosph...

Epiphytes and epibionts are a diverse and dynamic community of organisms that grow on and around seagrass leaves . They primarily consist of micro- and macroalgae, but also include invertebrates such as sponges, crustaceans, barnacles and spirorbid (coiled tube) worms. In healthy seagrass beds unaffected by nutrient pollution, epiphyte loads are low and generally consist of calcareous algae, diatoms, and spirorbid worms. Epiphytic algae require nutrients and photosynthesize just like seagrasses. As nutrient pollution increases, the amount of macroalgal epiphytes present on seagrass leaves increases as well. Older seagrass leaves tend to be more heavily epiphytized since there has been more time for the epiphytes to establish and grow. Heavy epiphyte loading is detrimental to seagrasses by reducing the quantity and quality of light available to photosynthetic tissues in the seagrass leaves , which can limit growth. Grazing by invertebrate herbivores is a primary mechanism at limiti...

Tropical cyclones often cause minimal and short-term damage to seagrass beds because the plants are protected by overlying waters. Each storm is unique and can directly and/or indirectly affect seagrasses .  Direct effects often include immediate responses to wind, waves, and currents such as the shearing of leaves (much like cutting your grass), the ripping out of whole plants as sediments are eroded away, or their burial as sediments are moved and deposited. Fortunately, if the rhizomes and roots in the sediment remain intact, new leaves may emerge after the storm. Indirect effects may reduce seagrass abundance over time and are often associated with elevated rainfall, reduced salinities, and impaired water quality and clarity. Storm runoff and prolonged high river flow linked to heavy rains on land can result in darkly colored waters in estuaries and coastal areas for weeks or months, reducing the amount of light available to seagrasses. Extended periods of reduced light av...

 The United Nations has designated March 1st as  World Seagrass Day  t o raise awareness about the threats to these ecosystems, Seagrasses are one of the most widespread marine ecosystems on Earth, covering around 300,000 km2 of seabed in 159 countries.  Monochromatic seagrass meadows may not be as colourful as coral reefs or as mysterious as mangrove forests. But they are havens for fish, protect coasts from storms and are key stores of carbon, making them some of the world’s most valuable natural spaces. Despite their importance, these ecosystems are in danger. A football field worth of seagrass disappears every 30 minutes and an estimated 7% of meadows are being lost worldwide per year. Ocean acidification, coastal development and rising ocean temperatures due to climate change are the prime drivers of seagrass loss. “ The seagrass ecosystem is a perfect example of nature in action, where habitats and the delicate web of life are intertwined in perfect harmony...