Spectral reflectance of three Western Atlantic subtropical/tropical dominant benthic seagrasses (Thalassia testudinum, Halodule wrightii and Syringodium filiforme) measured in the laboratory by UNIspec Spectral Analysis system over 400–1000 nm are compared to five Western Atlantic dominant benthic and intertidal algae (Fucus vesiculosus, Ulva lactuca, Halimeda incrassata, Udotea flabellum and Penicillus capitatus). Thalassia spectra are also compared to previously studied forest species, showing that the spectral reflectance signature of Thalassia was of the same general shape as forest species, but of lesser peak height (18% vs 28–50%) in the 750–759 nm range. For marine plants, near‐infrared reflectance of Thalassia, Syringodium and Halodule was intermediate (18%) between the ubiquitous green alga Ulva (15%) and the temperate brown alga, Fucus (27%). The brown alga had a unique spectral signature in the first difference spectrum (three secondary peaks at differing spectral values than the other species' secondary peaks). Comparisons between Halodule, Syringodium and Thalassia near‐infrared peaks and Halimeda (58%), Penicillus (29%) and Udotea (42%), subtropical/tropical algae, were also carried out. Halimeda differed most from the other green algae in terms of numerous oscillations from 450 to 700 nm seen in the first difference spectrum. The three seagrasses were similar in spectral reflectance curve shape to one another but differed somewhat in peak height. The first difference spectrum was helpful in pointing out subtle differences among the species and between algae and seagrass. Spectral reflectance data such as those presented here appear potentially useful for remote sensing of shallow habitats, and may additionally be used to monitor their health.

The greater Southeast Asian region contains the largest global extent of tropical seagrass; however, anthropogenic degradation is estimated to be greater than 7% per year. Although the areal extent of seagrass is presently 36,765 km ² , Fortes group estimates that 50% of the original seagrass has been degraded from a variety of impacts. One set of solutions to degradation is to restore tropical seagrass successfully, for which information from past results is needed to avoid failures. Van Katwijk, Thorhaug and others provided a global seagrass restoration review of 1,786 trials, but did not include the full Southeast Asian regional information. Thus, we review findings from 228 trials in the greater Southeast Asian region, involving 305,807 restored units with an extent of 372,649 m ² . Seagrasses planted with varying successes include 13 tropical species and five subtropical or near-subtemperate species. We compare methodologies as well as key factors of light level, energetics, and depth. This review demonstrates the highest survival in seagrass restoration employing sprigs or plugs at medium depths (2–4 m) with adequate light levels in medium to low energetics planting one to several dominant species. Substrate anchors improved successful establishment. Information gaps occur in quantified monitoring of seagrass services reassembled with tropical-seagrass restoration; thus, fisheries’ nursery potentials are not provided. Future actions need national seagrass restoration policies and plans to restore degraded seagrasses. At present, such policies and plans are non-existent in most greater Southeast Asian regional nations, with the exceptions of Australia and the Philippines, although some nations have national plans for restoring corals or mangroves.