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ECISMA NEWSLETTER Volume 5 julY 2014 The other exotic mangrove: Bruguiera gymnorrhiza at Kampong National Tropical Botanical Garden by Dennis J. Giardina, Florida Fish and Wildlife Conservation Commission

was established around the remaining mature tree to determine the seedling density and rate of spread of the population. As the group walked along the pathway in the middle of the forested peninsula, they were able to spot the specimen tree, which was almost 75 years old, pretty quickly. The bark was very dark and the structure of the tree reminiscent of a mature sweet bay magnolia.

Buds of Rhizophora mangle (left) and Bruguiera gymnorrhiza (right). (Photo by Dennis Giardina, FWC)

On a morning in March 2014, a group of Everglades Cooperative Species Management Area (ECISMA) partners visited the Kampong Tropical Botanic Garden. After a brief meeting in the living room of what was once David and Marian Fairchild’s home, Kampong curator David Jones and Harvard Professor Emeritus and Bruguiera gymnorrhiza propagule showing mangrove expert Barry Tomlinson led characteristic ribs that look a bit like okra. the group outside and down the slope (Photo by Dennis Giardina, FWC) of the backyard on Biscayne Bay to a small strip of land between two man- made boat basin canals where in 1940, two specimens of the non-native Saplings side by side, Bruguiera gymnorrhiza mangrove species Bruguiera (left) and Rhizophora mangle (right). (Photo gymnorrhiza were planted. by Dennis Giardina, FWC) Bruguiera gymnorrhiza is native to the non-native mangrove species planted diverse mangrove forests of East Africa, at both Fairchild and Kampong Asia, Australia and the Western Pacific. Botanical Garden prompted an inspection of their collections. The two specimens came from a collection made in Sulawesi, Indonesia. Of the fourteen documented exotic In his memoirs, David Fairchild wrote mangroves that were planted at Bruguiera gymnorrhiza flower calyx (the that he hoped his Bruguiera trees Fairchild, five remained. Interestingly, outer whorl of sepals that cup the petals of a flower). (Photo by Dennis Giardina) would eventually fruit and spread out of a total of 14 Bruguiera along the coast line, brightening it with gymnorrhiza trees planted there Bruguiera gymnorrhiza is a close their red flowers. between 1952 and 1971, none relative of the native red mangrove, remained. In 2008, after Lumnitzera racemosa, Rhizophora mangle, and it took a while another species of exotic mangrove, Of the two Bruguiera trees that were for the group to be able to distinguish was found to be invading the native planted at the Kampong, one was the smaller Bruguiera from red mangrove forests of Fairchild Tropical found to be alive and well, along with mangroves of the same size. Their Botanic Garden and neighboring at least 86 more of them in the foliage is strikingly similar and when Matheson Hammock County Park, a understory. A local survey was carried they are seedlings and saplings, they review of the records of the other out and a 21 by 21 meter research plot look a lot alike. Page 9

ECISMA NEWSLETTER Volume 5 julY 2014

mangrove species. They had hoped to be able to declare Lumnitzera gone, but after hundreds of man-hours and tens of thousands of dollars spent by the Florida Fish and Wildlife Conservation Commission, surveyors are still finding thousands of seedlings per acre per year at Matheson Hammock, four years after it was believed that the last reproductive tree was removed. Those involved in the ongoing effort agree that it is very fortunate that the Lumnitzera infestation is the result of an introduction from a single site. For most invasive species, there is a “lag phase,” a period of time between introduction and “critical mass,” when The ECISMA group with Dr. Barry Tomlinson (left to right - Robin Gray, Dennis Giardina, Andrew an invasive species population Derksen, Barry Tomlinson, Jennifer Possley, Gwen Burzycki and Dallas Hazelton). (Photo by explodes and begins to impact David Jones, Kampong Tropical Botanic Garden) ecosystem composition, structure and The leaves of Bruguiera have much function. For some species like more prominent drip tips. The petioles Lumnitzera, that period is short. (leaf stalks) and buds have a distinctive Certainly other related mangrove reddish color. The propagules of the species have proven to be invasive, two species are similarly shaped but including the native red mangrove, unlike the smooth exterior of red Rhizophora mangle. In 1902, red mangrove propagules those of mangroves from South Florida were Bruguiera are subtly ribbed, appearing planted on Molokai in the Hawaiian a bit like okra. Islands, which, because of their As the group became better at remoteness, never had any endemic identifying Bruguiera, they flagged the mangrove species. By 1917, it was ones they came across that did not recorded on neighboring Oahu and bear tags from the 2008 plot. During now it has been documented the survey, the ECISMA group was able throughout the archipelago, to verify that Bruguiera persists in the negatively impacting native plant and three separate polygons where they animal communities and proving very were originally mapped. difficult to control. At least five other mangrove species were introduced to The group felt somewhat relieved that Hawaii during the early 20th Century. Bruguiera gymnorrhiza population at While none of those have spread like the Kampong did not appear to be as Peninsula at Kampong with red circles red mangrove, two of them have aggressively invasive as the other indicating where Bruguiera gymnorrhiza was developed into self-sustaining exotic mangrove, Lumnitzera mapped in 2008. (Photo by Dennis Giardina, populations. One is another south racemosa. After the survey, the FWC) Florida native, buttonwood, ECISMA group and David Jones resample the 2008 plot and do a much Conocarpus erectus. The other species committed to reconvening in April to more exhaustive survey at the is Bruguiera gymnorrhiza. ♦ Kampong and along the coastline in the vicinity, especially in the pockets of mangroves to the north. It is reasonable to expect that the “Mangroves as Alien Species: The original tree has been reproductive for Case of Hawaii” by James A. at least half a century and that the Allen: http://bit.ly/mangHawaii inshore current has potentially carried “Are mangroves in the tropical away many Bruguiera propagules over Atlantic ripe for invasion? Exotic the years. Bruguiera seedlings are mangrove trees in the forests of remarkably shade tolerant and it is South Florida” possible that they could have http://bit.ly/mangsfla established over time in the dark interior of native mangrove stands if For everything you always high tides and storm events were wanted to know about repeatedly able to deposit enough of mangroves * but were afraid to them there. ask, download the United Nation’s Food and Agriculture The ECISMA partners who have Organization paper “The world’s participated in the five-year-long effort mangroves 1980 – 2005” to eradicate Lumnitzera racemosa are http://bit.ly/everythingmang Jennifer Possley with Bruguiera gymnorrhiza understandably wary of exotic seedlings. (Photo by Dennis Giardina, FWC)