Conserve Wildlife Blog

Reflecting on a Year of Growth for Seabeach Amaranth

August 16th, 2023

by Sherry Tirgrath, Wildlife Biologist

The population of seabeach amaranth (Amaranthus pumilus) in New Jersey has continued its upward trend for the 2023 season, marking another successful year of protecting the rare and vulnerable plant. Since 2019, CWF has partnered with the U.S. Fish and Wildlife Service – NJ Field Office (USFWS-NJFO) in monitoring and managing the state’s population of seabeach amaranth (SBA), a federally-threatened and state-endangered coastal plant. The number of SBA in the state fluctuates each year but suffered tremendously in the past due to coastal erosion, habitat loss, and disturbances from recreational use and municipal beach management. For 87 years, from 1913 until 2000, the species wasn’t seen in New Jersey. Plants have started rebounding on certain beaches in recent years, with numbers now in the thousands.

Seabeach amaranth beginning to bud

Plant totals reported in the state have grown steadily over the past three seasons, correlating with the increase in survey and protection efforts. With more plants comes the demand for additional assistance in locating and fencing them. CWF was able to increase its person power this year for the SBA project by hiring a seasonal field technician and adding a student intern provided through USFWS. Fencing measures have expanded and become more proactive since the project began, with certain beach sections being pre-fenced in the beginning of the season before SBA even begins to germinate. These pre-fenced sections typically contain large seed banks from the previous year’s plants and consistently have high numbers of SBA showing up at some point in the season. The SBA team uses past data to predict germination trends and prioritize sites for pre-fencing.

SBA seasonal technician, Aviva Lerman, and Stockton University/USFWS intern, Elizabeth (Libby) D’Albero fencing amaranth

At the time that this was written, a total of 2,451 plants were surveyed by CWFNJ, with more still likely to be discovered as the summer comes to a close. This number also includes two other rare beach plants that were surveyed during the season: seabeach knotweed (Polygonum glaucum) and sea sandwort (Honckenya peploides). While the total number of plants in the state in 2023 has significantly increased from prior years, the distribution has changed dramatically for a few sites. Some sites that were once strongholds, with hundreds of plants reported in the past, have very few to no plants germinating at all. The change in distribution is likely related to coastal storms and rising tides impacting the shoreline. Seed banks can be lost as sand is washed away by high waters flooding the beaches. Thankfully, the seeds can survive in the ocean for some time, eventually making their way back to dry beach. The plants depend on seed dispersal through wind and tides, although too much beach erosion reduces habitat available for the plants to grow.

Crowding out by other vegetation, including invasive species like Asiatic sand sedge, as well as municipal beach management activities like raking and sand-scraping that can alter the habitat or directly destroy plants, also contributed to declines of SBA on some beaches. CWF works with USFWS to prepare site-specific Beach Management Plans (BMPs) that outline the responsibilities of beach managers and the government in protecting vulnerable beach habitats and species. These BMPs designate certain sections of a beach as plant protection zones where vehicles and rakes are forbidden. This allows vegetation to grow mostly uninhibited, and it is usually where most SBA and other rare species germinate.

The SBA season can extend well in the fall. The plants are annuals, which means they do not remain year-round. Once the plants flower and drop their seeds, they slowly begin to die off. The fencing around the plants typically stays up until the plants appear dead or have disappeared, sometime in November or December. CFWNJ will continue to monitor and maintain the fenced SBA, as well as survey for any new ones that emerge.

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One Response to “Reflecting on a Year of Growth for Seabeach Amaranth”

  1. nayan says:

    The plants are annuals, which means they do not remain year-round.