THORHAUG, ANITRA. 658 NE 70 ST. , Miami, Fl. 33138. - Test Plots of Seagrass Species Affecting Long-term Survival of Restored Seagrass.
Four test plot programs were carried out for 3 species (Thalassia
testudinum, Halodule wrightii, and Syringodium filiforme)and 3
tech-niques in Biscayne Bay, Florida over 22 years.In Laguna
Madre,Texas, one test plot program with 2 species (Halodule wrightii
and Halophila species),and 2 techniques were used. The result of test
plot programs were used for larger scale restorations from 2 to 75
acres. The results of the larger scale plantings are judged by the
investigator to have increased survival by the plantings. 1.) Some
desirable sites to restore were shown to be beyond the photo
compensation limits; 2.) Other barren sites were too energetic for any
of the techniques to allow the development of transplant units; 3.)
Some techniques originally preferred for abundance of specimens or
ease of transport were not highly useful at necessary sites when
tested; 4.) Some species, which would have been acceptable by the
permitting agency or investigating scientist, did not demonstrate high
survival. The three test plot studies in Biscayne Bay were carried out
in 1976, 1982-2000. Test plots led to 6 larger plantings from 1.5 to
35 acres. The results led to separation of variables such as species,
technique, site, depth, energy regime. The results of the larger scale
planting were from 60 to 92% successful and led to large areas in and
around the restored areas growing dense over short and long term.
However, a gale-force winter storm at the 35-acre site 5 months after
planting resulted in a one-third reduction in planted units. The
Laguna Madre Texas sites led to a 75-acre planting. The best
techniques and species were utilized as well as having a clear concept
of photo-compensation for depth which differed from that in the
literature. Over 70% survival occurred despite a Hurricane and
tornados which lowered the survival rates.
Key words: Biscayne Bay Fl, Halodule Syringodium, Laguna Madre TX, restoration, seagrass, Thalassia Halophila