Decadal dynamics of subtidal barrens habitat

Glasby, Tim M.; Gibson, Peter T.

doi:10.1016/j.marenvres.2019.104869

Cited by 17 publications

(11 citation statements)

References 82 publications

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“…From this date to the recent mass mortality events, there has been an unstoppable advance of sea urchin barrens (Hernández 2017). Once formed, barrens are a long‐lasting state limiting biodiversity of rocky ecosystems (Medrano et al 2019; Glasby and Gibson 2020). A large‐scale reduction of the D .…”

Section: Discussionmentioning

confidence: 99%

Recurrent large‐scale sea urchin mass mortality and the establishment of a long‐lasting alternative macroalgae‐dominated community state

Sangil

Hernández

2021

Limnology & Oceanography

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Relationships between sea urchins and noncrustose macroalgae are typically nonlinear, and an abrupt phase shift from a barren to a macroalgae-dominated state and vice versa happens when the sea urchin abundance exceeds a critical threshold. Here, we have used two mass mortality events as a natural experiment to study progressive changes and dynamics between these stable states. In 2009-2010 and 2018, two mass mortalities decimated the populations of the sea urchin Diadema africanum in the Canary Islands (Eastern Subtropical Atlantic). In these islands, this sea urchin is a key-herbivore controlling the growth of macroalgae, and sea urchin barrens have persisted for more 60 yr. Mass mortality events differed in intensity both in space and time, and two phase shifts from sea urchin barrens to macroalgal beds were detected in both when sea urchin density declined below a critical threshold of 4 indv. Á m À2 . The first mass mortality was greater in La Palma Island, consequently in this island a long-lasting alternative state dominated by noncrustose macroalgae has been established. Subsequently, a recurrent mass mortality also favored the transition from the sea urchin barrens to noncrustose macroalgal beds in Tenerife Island. After mass mortalities, D. africanum populations were reduced by 94-98% in both islands. No signs of recovery of these populations have been identified after phase shifts; ecosystem feedbacks may be the cause of the low population density of D. africanum.

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Section: Discussionmentioning

confidence: 99%

Recurrent large‐scale sea urchin mass mortality and the establishment of a long‐lasting alternative macroalgae‐dominated community state

Sangil

Hernández

2021

Limnology & Oceanography

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“…The extent to which the abundance of these urchins on NSW rocky reefs is a natural phenomenon or reflects change owing to human impacts on reef ecology has been a focus of media and policy; however, extensive research points to the former. In NSW, this species is critical for the diversity of reef-based habitats to the south of Port Stephens (Glasby and Gibson 2020). Accordingly, the impact of increased fishing effort or culling in NSW could have a deleterious effect on reef habitats.…”

Section: Background and Perspectivementioning

confidence: 99%

“…A wide range of fishes depend on these diverse habitats for shelter, food and as spawning sites and most require multiple habitats to meet their needs (Curley et al 2013a). Archival aerial photography of reefs at some NSW sites has indicated that urchin-grazed barrens, be they small or more extensive areas with abundant crevices, have been a feature of the NSW seascape for ~50 years (Glasby and Gibson 2020). There is no indication that the representation of urchin-grazed barrens on reefs, to a depth of 10 m or less, has changed more than ±~10% (Glasby and Gibson 2020).…”

Section: Background and Perspectivementioning

confidence: 99%

New South Wales rocky reefs are under threat

Kingsford

Byrne

2023

Mar. Freshw. Res.

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Rocky reefs of New South Wales (NSW) are characterised by a mosaic of habitats, including kelp forest and urchin-grazed barrens. These habitats support a diversity of dependent species. Decades of research have demonstrated that kelps form extensive forests with distinctive fish and invertebrate faunas and the ‘barrens’ boulder habitat provides shelter and other resources for commercial fishes, charismatic fishes and invertebrates; the barrens are not deserts! The feeding activities of herbivorous invertebrates, particularly the black sea urchin (Centrostephanus rodgersii) determine the presence of barrens habitat. Some invertebrates survive only in the presence of urchins and are the food resources for many predatory fishes. The barrens habitat in NSW has been highly stable for decades and is critical for the diversity of reef-based organisms. Because of climate change, Tasmanian waters have warmed and as a result C. rodgersii larvae have dispersed southward from NSW. Importantly, the situation regarding C. rodgersii in Tasmania differs from the established pattern in NSW and this needs to be recognised in the approach to management of this species in the two states. Urchins in NSW should be appreciated as important habitat determiners and the removal of them for whatever purpose would have to be managed carefully.

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“…Pilot projects including herbivore removal and kelp outplanting are beginning and interest for more effort is high but identifying locations for restoration efforts has been challenging across such a large geography. Remote sensing offers an efficient option for mapping areas where kelp has been lost (including urchin barrens; Carnell and Keough, 2019; Glasby and Gibson, 2020), locating remnant kelp patches (for spore production), selecting sites that may be suitable for restoration based on the history of kelp presence and persistence, and monitoring the impacts of restoration efforts over time (Gleason et al, 2021).…”

Section: Kelp Forest Restorationmentioning

confidence: 99%

A Review of the Opportunities and Challenges for Using Remote Sensing for Management of Surface-Canopy Forming Kelps

et al. 2021

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Surface-canopy forming kelps provide the foundation for ecosystems that are ecologically, culturally, and economically important. However, these kelp forests are naturally dynamic systems that are also threatened by a range of global and local pressures. As a result, there is a need for tools that enable managers to reliably track changes in their distribution, abundance, and health in a timely manner. Remote sensing data availability has increased dramatically in recent years and this data represents a valuable tool for monitoring surface-canopy forming kelps. However, the choice of remote sensing data and analytic approach must be properly matched to management objectives and tailored to the physical and biological characteristics of the region of interest. This review identifies remote sensing datasets and analyses best suited to address different management needs and environmental settings using case studies from the west coast of North America. We highlight the importance of integrating different datasets and approaches to facilitate comparisons across regions and promote coordination of management strategies.

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Decadal dynamics of subtidal barrens habitat

Cited by 17 publications

References 82 publications

Recurrent large‐scale sea urchin mass mortality and the establishment of a long‐lasting alternative macroalgae‐dominated community state

Recurrent large‐scale sea urchin mass mortality and the establishment of a long‐lasting alternative macroalgae‐dominated community state

New South Wales rocky reefs are under threat

A Review of the Opportunities and Challenges for Using Remote Sensing for Management of Surface-Canopy Forming Kelps

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