Location of the Giant Kelp (Macrocystis pyrifera) outplant trial sites. This is part of a collaborative project between IMAS, The Nature Conservancy, CSIRO and NRM South to restore giant kelp forests in Tasmania.

An aerial survey was conducted for giant kelp (Macrocystis pyrifera) on the east coast of Tasmania from Eddystone Point to Southeast Cape. This survey represents part of a series of similar surveys, with historic aerial surveys having been conducted in 1986 and 1999. The survey was conducted via light aircraft. Areas of visable Macrocystis pyrifera beds were marked on topographical land tenure maps using landmarks as references, and complimentary photo footage was collected.

The main aim of this research program was to determine the potential for reducing the density of urchins to encourage the return of seaweeds and an improvement in urchin roe quality and quantity from remaining urchins. Tasmanian Sea Urchin Developments used two widely-separated sub-tidal experimental lease areas. One of these areas was at Meredith Point, on the east coast, and the other at Hope Island, on the south coast. Both sites had been subject to some overgrazing by urchins. At Meredith Point, the study area was divided into plots containing urchins at three densities: artificially enhanced, continually harvested and control (undisturbed). At Hope Island, controlled clearings of urchins and limpets from barrens areas were conducted. Recovery of vegetation was monitored as well as urchin roe quality and quantity. The data represented by this record was collected at Hope Island, and includes results from an inital survey collected at the site before the main study commenced.

A project investigating the restoration of string kelp (Macrocystis pyrifera) habitat on Tasmania's east and south coasts. Macroalgae, fish and invertebrate counts were collected as part of the project using the Edgar Barrett transect technique in the Derwent Estuary and in the Mercury Passage on the South East Tasmania. Other fish, invertebrate and macroalgal data was also collected.

Giant kelp (Macrocystis pyrifera) forests are a foundational habitat that dominates many nearshore rocky coastlines in temperate and cold-water regions worldwide. Macrocystis forests can extend as much as 40 m to the surface and form closed canopies that alter the light, current, and sedimentation environment beneath them. They play an ecosystem-structuring function and provide habitat for a diverse range of fish and invertebrate species. The coastal waters of Tasmania represent the most extensive giant kelp habitat in Australia. Dense forests have historically covered large areas of the nearshore reef habitat, but significant declines have been recorded in eastern Tasmania in recent decades. These losses are thought to be linked to environmental stressors such as extended periods of high water movement, warming sea temperatures, and nutrient depletion. Eastern Tasmania has experienced some of the most pronounced declines, leading to the 2012 listing of the giant kelp community as an ‘endangered marine community type’ under Australia’s Federal Environment Protection and Biodiversity Conservation Act. This dataset uses Landsat satellite imagery to quantifiy the spatial extent and temporal variability of giant kelp surface canopies along the Tasmanian coastline to address gaps in long-term monitoring. The data collection is divided into two components: 1) A statewide analysis that maps the extent of Macrocystis pyrifera canopies across the whole Tasmanian coastline, grouped into nine three-year bins spanning 1987–2015. This long-term dataset is intended for assessing long-term (decadal) changes at a broad spatial scale. 2) A higher temporal-resolution analysis of 24 specific sites along the Tasmanian coastline. This dataset includes canopy coverage from all cloud-free Landsat imagery captured over the period 1986-2015 to enable detailed analysis of seasonal and interannual fluctuations in kelp canopy extent and understand localised population dynamics.

Australia's kelp forests are among the most productive and biodiverse ecosystems on the planet. Giant kelp (Macrocystis pyrifera) can develop extensive forests and create dense surface canopies, providing a variety of ecological functions and ecosystem services including carbon sequestration, nutrient cycling and habitat provision. Giant Kelp forests naturally fluctuate from year to year and experience dramatic interannual variability. However, over the last 4–5 decades, a ~95% loss of surface-canopy forests has been recorded in eastern Tasmania due to a combination of ocean warming, changing currents, recruitment limitation, and intense herbivory by expanding sea urchin populations. While kelp forests also occur on mainland southeastern Australia, relatively little is known about the ecology of Giant Kelp in this region. In recognition of the species' rapid declines in eastern Tasmania and the lack of data elsewhere, Giant Kelp communities in Australia were declared an endangered marine community in August 2012 under the EPBC Act. Given the conservation status of Australian Giant Kelp communities, ongoing threats, and absence of a sanctioned recovery plan, there is an urgent need to establish the current extent for Giant Kelp in Australia, and to monitor changes over time. Historical aerial surveys techniques are costly, logistically difficult, and prone to cloud interference - impairing the ability of resource managers to consistently assess Giant Kelp abundance and distribution across jurisdictions. Recent improvements satellite remote sensing techniques now offer a reliable and cost-effective means for long-term kelp canopy monitoring at broad spatial and temporal scales. This project mapped the surface canopy of Giant Kelp forests from 2016 to 2023 using 3 m resolution satellite imagery across the known historical range in Tasmania, Victoria, southern New South Wales, and eastern South Australia. The mapping workflow was divided into the following broad steps: • Generate a precise land/water mask to exclude intertidal areas • Create a first-pass machine learning (ML) classification using Sentinel-2 (10 m) imagery • Acquire and process PlanetScope (3 m) daily imagery • Train and evaluate a second-pass ML model for kelp detection using PlanetScope imagery • Visualise results via an interactive Earth Engine application to enable input from expert review ---DATA DESCRIPTION--- • KelpWatch_V3_KelpExtent_ALL_shp.zip: binary kelp extent - by year x zone (near-coast vs open water) • KelpWatch_V3_KelpProb_ALL.zip: continuous probability of kelp - by year x zone x threshold (low vs high)

This record describes an aggregated data product compiled from a number of different surveys of Macrocystis surface cover in Tasmanian waters, spanning 1950 to 2019. Some surveys represent a statewide census of Macrocystis cover, while others are targeted surveys of smaller regions. Methodology and data quality may also vary between surveys. Please see linked metadata records for specific methodologies and quality statements applying to individual surveys.