|Reciprocal transplanting of the threatened seagrass Halophila johnsonii (Johnson's Seagrass) in the Indian River lagoon, Florida|
Heidelbaugh, W.S.; Hall, L.M.; Kenworthy, W.J.; Whitfield, P.; Virnstein, R.W.; Morris, L.J.; Hanisak, M.D. (2000). Reciprocal transplanting of the threatened seagrass Halophila johnsonii (Johnson's Seagrass) in the Indian River lagoon, Florida, in: Bortone, S.A. (Ed.) Seagrasses: monitoring, ecology, physiology, and management. pp. 197-210
In: Bortone, S.A. (Ed.) (2000). Seagrasses: monitoring, ecology, physiology, and management. CRC Marine Science Series, 16. CRC Press: Boca Raton. ISBN 0-8493-2045-3. 318 pp., more
In: Kennish, M.J.; Lutz, P.L. (Ed.) CRC Marine Science Series., more
|Authors|| || Top |
- Heidelbaugh, W.S.
- Hall, L.M.
- Kenworthy, W.J.
- Whitfield, P.
- Virnstein, R.W.
- Morris, L.J.
- Hanisak, M.D.
Successful relocation of Halophila johnsonii (Johnson's seagrass) may be essential for its long-term survival. H. johnsonii is one of the smallest and rarest seagrass species. lt has a limited geographic range, and within its range, it is discontinuous and patchy. Male flowers of H. johnsonii have never been found; populations may be maintained exclusively by vegetative growth and reproduction. Based on these characteristics, H. johnsonii has been listed as threatened by the National Marine Fisherles Service. Reciprocal transplants were performed in May 1998 to determine the feasibility of relocation and restoration of local populations in the Indian River Lagoon, Florida. Three different sites were selected which varied primarily in mean depth, light penetration, and degree of tidal exchange- Intact plugs of H. johnsonii, composed of leaf pairs, roots, rhizomes, and associated sediment, were harvested, put into peat pots, and transplanted within several hours of removal. Transplant and control plots were monitored biweekly for 30 weeks. The peat pot method was initially successful; however, all three recipient sites had different problems which ultimately caused the loss of all transplant materials. Lagoon Shallow site increased by week 4 to a maximum of 71% cover, followed by an abrupt decline when plots were exposed due to low water levels in June/July. Lagoon Deep site initially increased to a maximum of 88% cover, followed by a gradual decline as light decreased to only 1.3% of surface incident light, weIl below seagrass light requirements. Sebastian lnlet site also showed an initial increase to a maximum of 95% cover, foIlowed by a gradual decrease associated with sediment burial and/or erosion. Although coverage declined at the transplant sites, beds of H. johnsonii at all three donor sites similarly declined. The mortality in the transplant plots was not necessarily a result of the methodology, but more likely a reflection of the inherent dynamic nature of the species.