Spatial and temporal variability of seagrass at Lizard Island, Great Barrier Reef

Abstract

Increasing threats to natural ecosystems from local and global stressors are reinforcing the need for baseline data on the distribution and abundance of organisms. We quantified spatial and/or temporal patterns of seagrass distribution, shoot density, leaf area index, biomass, productivity, and sediment carbon content in shallow water (0-5 m) at Lizard Island, Great Barrier Reef, Australia, in field surveys conducted in December 2011 and October 2012. Seagrass meadows were mapped using satellite imagery and field validation. A total of 18.3 ha of seagrass, composed primarily of Thalassia hemprichii and Halodule uninervis, was mapped in shallow water. This was 46% less than the area of seagrass in the same region reported in 1995, although variations in mapping methods may have influenced the magnitude of change detected. There was inter-annual variability in shoot density and length, with values for both higher in 2011 than in 2012.Seagrass properties and sediment carbon content were representative of shallow-water seagrass meadows on a mid-shelf Great Barrier Reef island. The data can be used to evaluate change, to parameterize models of the impact of anthropogenic or environmental variability on seagrass distribution and abundance, and to assess the success of management actions.

Multiple Stable States and Catastrophic Shifts in Coastal Wetlands: Progress, Challenges, and Opportunities in Validating Theory Using Remote Sensing and Other Methods

“…Several recent studies also focused on the spatial and temporal variability of seagrasses [252][253][254][255][256][257][258][259]. Some studies document remarkable stability of seagrass meadows over long time periods.…”

Spatiotemporal variability in the structure of seagrass meadows and associated macrofaunal assemblages in southwest England (UK): Using citizen science to benchmark ecological pattern

“…The structure of seagrass meadows did vary somewhat between the survey years, as fragmentation and shoot density differed between 2016 and 2017 at one and all of the three locations, respectively. With only 2 years of survey data, it is not possible to discern long‐term temporal trends or infer drivers of this pattern, but it is worth noting that pronounced interannual variability in seagrass population density has been observed previously (Bull & Keyton, ; Frederiksen et al, ; Saunders et al, ), as a consequence of interannual variability in wave disturbance (Frederiksen et al, ), light and nutrient availability (Moore, Shields, & Parrish, ; Saunders et al, ) or climatic variables (Marbà & Duarte, ), for example. Such between‐year variability has important implications for monitoring programmes and condition assessments, as high‐resolution sampling is needed in order to differentiate between “noise” and “trends.” This is certainly not the case for many UK seagrass populations, which are routinely monitored every ~6 years (see Jackson et al, for further discussion).…”

A Review of Remote Sensing Approaches for Monitoring Blue Carbon Ecosystems: Mangroves, Seagrassesand Salt Marshes during 2010–2018

“…Using simple radiative transfer modelling for water column correction, the corrected WorldView-2 produced a seagrass map with 88.3% OA [114]. Similar research was conducted for mapping of seagrass distribution around Lizard Island, Australia [115] using the OBIA and the radiative transfer modelling-based simulator [116]. For the IKONOS sensor, the selected works were [117,118] with a remarkable density index developed by Baumstark et al [119].…”