Halophila johnsonii - Eiseman
Johnson's Sea-grass
Taxonomic Status: Accepted
Related ITIS Name(s): Halophila johnsonii Eiseman (TSN 502870)
Unique Identifier: ELEMENT_GLOBAL.2.143898
Element Code: PMHYD04050
Informal Taxonomy: Plants, Vascular - Flowering Plants - Other flowering plants
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Hydrocharitales Hydrocharitaceae Halophila
Check this box to expand all report sections:
Concept Reference
Help
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Halophila johnsonii
Taxonomic Comments: Short et al. (2010) found no genetic deviation (using nrDNA sequences) between plants of Halophila ovalis from Antigua and plants of H. johnsonii from Florida.  Short et al.'s (2010) report of H. ovalis in Antigua is the first report of H. ovalis from the Tropical Atlantic bioregion; it was previously known only from the Tropical Indo-Pacific bioregion.  Short et al. (2012), suggest two possible hypotheses to explain the presence of H. ovalis in the Atlantic flora: disperal via dredging or another human maritime activity, or long-distance natural dispersal via rafting/floating of vegetative fragments.
Conservation Status
Help

NatureServe Status

Global Status: G2Q
Global Status Last Reviewed: 01Jun1993
Global Status Last Changed: 01Jun1993
Rounded Global Status: G2 - Imperiled
Reasons: Narrowly endemic to coastal lagoons in eastern Florida. There are 10 reported occurrences. The species is threatened with destruction from dredge and fill, turbidity, eutrophication, and thermal pollution - all due to the high population pressure along Florida's east coast.
Nation: United States
National Status: N2

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Florida (S2)

Other Statuses

U.S. Endangered Species Act (USESA): LT: Listed threatened (14Sep1998)
Comments on USESA: The National Oceanic and Atmospheric Administration (NOAA) determined Halophila johnsonii to be a threatened species on September 14, 1998. The Fish and Wildlife Service added H. johnsonii to the List of Endangered and Threatened Plants (List) as a threatened species on May 26, 1999. The amendment to the List was based on the determination by the National Oceanic and Atmospheric Administration, which has jurisdiction for this species, published on September 14, 1998 (Fish and Wildlife Service 1999).

NatureServe Global Conservation Status Factors

Range Extent Comments: Restricted to coastal lagoons in eastern Florida from Sebastian Inlet to Virginia Key in Biscayne Bay. Extends from Brevard, St. Lucie, Martin, Dade, and Palm Beach counties.

Number of Occurrences: 6 - 20
Number of Occurrences Comments: 10 Element Occurrences listed in log.

Population Size Comments: Rhizomatous species forming underwater mats - not much data on Number of genets - may be an apomict. H. johnsonii must be considered one of the least abundant seagrasses in the Indian River Lagoon (Kenworthy,1993).

Overall Threat Impact Comments: Seagrass beds have shown a documented decline in area within Indian River lagoon and Biscayne Bay.

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Removed from state endangered species list in December of 1996. As a colonizer species, it will appear abundantly for a time in some areas and then disappear only to reappear in another area. This species is not believed to be in danger of extinction at the present time (Johnson, pers.comm, 1996)

Intrinsic Vulnerability Comments: Species is narrowly endemic to lagoons along the east coast of Florida; it is threatened (along with other members of the seagrass community) with destruction from dredge and fill, turbidity, eutrophication, and thermal pollution due to high population pressure along this segment of the coast.

Other NatureServe Conservation Status Information

Distribution
Help
Global Range: Restricted to coastal lagoons in eastern Florida from Sebastian Inlet to Virginia Key in Biscayne Bay. Extends from Brevard, St. Lucie, Martin, Dade, and Palm Beach counties.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map

U.S. & Canada State/Province Distribution
United States FL

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
FL Martin (12085), Miami-Dade (12086)*, Palm Beach (12099), St. Lucie (12111)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Vero Beach (03080203)+, Florida Southeast Coast (03090206)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Help
Basic Description: A rhizomatous seagrass, forming low mats. Leaves are distinctly petiolate; leaf margins are entire (Wunderlin 1982).
Marine Habitat(s): Near shore
Estuarine Habitat(s): River mouth/tidal river, Tidal flat/shore
Habitat Comments: Rhizomatous seagrass forming low mats either in pure stands or with shoalgrass (Halodule wrightii) in intertidal areas (6" to 6' depth).
Economic Attributes Not yet assessed
Help
Management Summary Not yet assessed
Help
Population/Occurrence Delineation Not yet assessed
Help
Population/Occurrence Viability
Help
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
Help
Authors/Contributors
Help
NatureServe Conservation Status Factors Edition Date: 15Jul1988
NatureServe Conservation Status Factors Author: Johnson, A.F.

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
Help
  • Eiseman, N.J. and McMillan, C. 1980. A new species of seagrass, Halophila johnsonii, from the Atlantic coast of Florida. Aquatic Botany 9: 15-19.

  • Fish and Wildlife Service. 1999. Endangered and threatened wildlife and plants; Threatened status for Johnson's Seagrass. Federal Register 64(101):28392-28393.

  • Flora of North America Editorial Committee. 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.

  • KRAL, R. 1983.A REPORT ON SOME RARE,THREATENED,OR ENDANGEREDFOREST-RELATED VASCULAR PLANTS OF THE SOUTH.VOL I ISOETACEAETHROUGH EUPHORBIACEAE;VOL II AQUIFOLIACEA THROUGH ASTERACEAE& GLOSSARY.USDA FOREST SERV,SE REG.,ATL,GA. TECH PUBL R8-TP2

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kenworthy, W. Judson. 1993. The distribution, abundance, and ecology of Halophila johnsonii Ersinian in the lower Indian River, Florida. Final report to the office of protected resources, Natl. Marine Fisheries Service, Silver Spring, MD.

  • Kral, R. 1983c. A report on some rare, threatened, or endangered forest-related vascular plants of the South. U.S. Dept. of Agriculture Forest Service Technical Publication R8-TP2, Athens, GA. 1305 pp.

  • Short, F.T., G.E. Moore, and K.A. Peyton. 2010. Halophila ovalis in the tropical Atlantic Ocean. Aquatic Botany 93: 141-146.

  • WUNDERLIN, RICHARD P. 1982. GUIDE TO THE VASCULAR PLANTS OF CENTRAL FLORIDA. UNIV. PRESSES OF FLA., TAMPA, ST. PETERSBURG, FT. MEYERS, SARASOTA

  • Wunderlin, R.P. 1982. Guide to the vascular plants of central Florida. Univ. Presses Florida, Gainesville. 472 pp.

  • Wunderlin, R.P., B.F. Hansen, and E.L. Bridges. 1996. Atlas of Florida Vascular Plants. Published on the Internet: http://www.usf.edu/isb/projects/atlas/atlas.html

Use Guidelines & Citation

Use Guidelines and Citation

The Small Print: Trademark, Copyright, Citation Guidelines, Restrictions on Use, and Information Disclaimer.

Note: All species and ecological community data presented in NatureServe Explorer at http://explorer.natureserve.org were updated to be current with NatureServe's central databases as of March 2018.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2018 NatureServe, 4600 N. Fairfax Dr., 7th Floor, Arlington Virginia 22203, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2018. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available http://explorer.natureserve.org. (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:
http://www.natureserve.org/library/birdDistributionmapsmetadatav1.pdf.

Full metadata for the Mammal Range Maps of North America is available at:
http://www.natureserve.org/library/mammalsDistributionmetadatav1.pdf.

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
Information Warranty Disclaimer: All documents and related graphics provided by this server and any other documents which are referenced by or linked to this server are provided "as is" without warranty as to the currentness, completeness, or accuracy of any specific data. NatureServe hereby disclaims all warranties and conditions with regard to any documents provided by this server or any other documents which are referenced by or linked to this server, including but not limited to all implied warranties and conditions of merchantibility, fitness for a particular purpose, and non-infringement. NatureServe makes no representations about the suitability of the information delivered from this server or any other documents that are referenced to or linked to this server. In no event shall NatureServe be liable for any special, indirect, incidental, consequential damages, or for damages of any kind arising out of or in connection with the use or performance of information contained in any documents provided by this server or in any other documents which are referenced by or linked to this server, under any theory of liability used. NatureServe may update or make changes to the documents provided by this server at any time without notice; however, NatureServe makes no commitment to update the information contained herein. Since the data in the central databases are continually being updated, it is advisable to refresh data retrieved at least once a year after its receipt. The data provided is for planning, assessment, and informational purposes. Site specific projects or activities should be reviewed for potential environmental impacts with appropriate regulatory agencies. If ground-disturbing activities are proposed on a site, the appropriate state natural heritage program(s) or conservation data center can be contacted for a site-specific review of the project area (see Visit Local Programs).

Feedback Request: NatureServe encourages users to let us know of any errors or significant omissions that you find in the data through (see Contact Us). Your comments will be very valuable in improving the overall quality of our databases for the benefit of all users.