1
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Johnson CR, Dudgeon S. Understanding change in benthic marine systems. ANNALS OF BOTANY 2024; 133:131-144. [PMID: 38079203 PMCID: PMC10921837 DOI: 10.1093/aob/mcad187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 12/10/2023] [Indexed: 03/09/2024]
Abstract
BACKGROUND The unprecedented influence of human activities on natural ecosystems in the 21st century has resulted in increasingly frequent large-scale changes in ecological communities. This has heightened interest in understanding such changes and effective means to manage them. Accurate interpretation of state changes is challenging because of difficulties translating theory to empirical study, and most theory emphasizes systems near equilibrium, which may not be relevant in rapidly changing environments. SCOPE We review concepts of long-transient stages and phase shifts between stable community states, both smooth, continuous and discontinuous shifts, and the relationships among them. Three principal challenges emerge when applying these concepts. The first is how to interpret observed change in communities - distinguishing multiple stable states from long transients, or reversible shifts in the phase portrait of single attractor systems. The second is how to quantify the magnitudes of three sources of variability that cause switches between community states: (1) 'noise' in species' abundances, (2) 'wiggle' in system parameters and (3) trends in parameters that affect the topography of the basin of attraction. The third challenge is how variability of the system shapes evidence used to interpret community changes. We outline a novel approach using critical length scales to potentially address these challenges. These concepts are highlighted by a review of recent examples involving macroalgae as key players in marine benthic ecosystems. CONCLUSIONS Real-world examples show three or more stable configurations of ecological communities may exist for a given set of parameters, and transient stages may persist for long periods necessitating their respective consideration. The characteristic length scale (CLS) is a useful metric that uniquely identifies a community 'basin of attraction', enabling phase shifts to be distinguished from long transients. Variabilities of CLSs and time series data may likewise provide proactive management measures to mitigate phase shifts and loss of ecosystem services. Continued challenges remain in distinguishing continuous from discontinuous phase shifts because their respective dynamics lack unique signatures.
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Affiliation(s)
- Craig R Johnson
- Institute for Marine & Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania, Australia 7001, and
| | - Steve Dudgeon
- Department of Biology, California State University, Northridge, CA 91330-8303, USA
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2
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Belleza DFC, Urae T, Tanimae SI, Toyama K, Isoda A, Nishihara GN. The behavior of sympatric sea urchin species across an ecosystem state gradient. PeerJ 2023; 11:e15511. [PMID: 37334121 PMCID: PMC10274604 DOI: 10.7717/peerj.15511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 05/15/2023] [Indexed: 06/20/2023] Open
Abstract
Background In temperate macroalgal forests, sea urchins are considered as a keystone species due to their grazing ability. Given their potential to shape benthic communities, we monitored the habitat use by three sympatric sea urchin species and compared their behaviors in a vegetated habitat (VH) and an adjacent isoyake habitat (IH). Methods We monitored the environmental conditions and sea urchin density along deep and shallow transects of the VH and IH for over a year. The benthic rugosity at both sites were also surveyed. A mark-recapture experiment was conducted on the two most abundant sea urchins, Diadema setosum and Heliocidaris crassispina, to elucidate sea urchin movement patterns and group dynamics. Results We found that exposure to waves was highest at the VH while the IH was sheltered. The deep IH experienced the least amount of light due to high turbidity. Water temperature patterns were similar across sites. The VH benthic topography was more rugose compared to the smoother and silt-covered IH substate. Peak macroalgal bloom occurred three months earlier in IH, but macroalgae persisted longer at the shallow VH. Among the sympatric sea urchins, H. crassispina was most abundant at the shallow VH and was observed in pits and crevices. The most abundant across IH and in the deep VH was D. setosum, preferring either crevices or free-living, depending on hydrodynamic conditions. The least abundant species was D. savignyi, and most often observed in crevices. Small and medium sea urchins were most often observed at the IH site, whereas larger sea urchins were more likely observed at the VH. The mark-recapture study showed that D. setosum was found to displace further at the IH, and H. crassispina was more sedentary. Additionally, D. setosum was always observed in groups, whereas H. crassispina was always solitary. Discussion The behaviors of sympatric urchins, Diadema savignyi, D. setosum and H. crassispina, differed in response to changes in the benthic environment and physical conditions. Sea urchin displacement increased when rugosity and wave action were low. Habitat preference shifted to crevices in seasons with high wave action. In general, the mark-recapture experiment showed that sea urchins displaced further at night.
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Affiliation(s)
- Dominic Franco C. Belleza
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki City, Nagasaki, Japan
| | - Takeshi Urae
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki City, Nagasaki, Japan
| | - Shin-ichiro Tanimae
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki City, Nagasaki, Japan
| | - Kento Toyama
- Faculty of Fisheries, Nagasaki University, Nagasaki City, Nagasaki, Japan
| | - Akari Isoda
- Faculty of Fisheries, Nagasaki University, Nagasaki City, Nagasaki, Japan
| | - Gregory N. Nishihara
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki City, Nagasaki, Japan
- Organization for Marine Science and Technology, Institute for East China Sea Research, Nagasaki University, Nagasaki City, Nagasaki, Japan
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3
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Young MA, Critchell K, Miller AD, Treml EA, Sams M, Carvalho R, Ierodiaconou D. Mapping the impacts of multiple stressors on the decline in kelps along the coast of Victoria, Australia. DIVERS DISTRIB 2022. [DOI: 10.1111/ddi.13654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Mary A. Young
- Centre for Integrative Ecology, School of Life and Environmental Sciences Deakin University Warrnambool Vic. Australia
| | - Kay Critchell
- Centre for Integrative Ecology, School of Life and Environmental Sciences Deakin University Queenscliff Vic. Australia
| | - Adam D. Miller
- Centre for Integrative Ecology, School of Life and Environmental Sciences Deakin University Warrnambool Vic. Australia
| | - Eric A. Treml
- Centre for Integrative Ecology, School of Life and Environmental Sciences Deakin University Queenscliff Vic. Australia
| | - Michael Sams
- Parks Victoria, Marine and Coastal Science and Programs Melbourne Vic. Australia
| | - Rafael Carvalho
- School of Earth, Atmosphere and Environment Monash University Melbourne Vic. Australia
| | - Daniel Ierodiaconou
- Centre for Integrative Ecology, School of Life and Environmental Sciences Deakin University Warrnambool Vic. Australia
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4
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Reeves SE, Kriegisch N, Johnson CR, Ling SD. Kelp habitat fragmentation reduces resistance to overgrazing, invasion and collapse to turf dominance. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. E. Reeves
- Institute for Marine and Antarctic Studies University of Tasmania, 20 Castray Esplanade, Battery Point Tasmania Australia
| | - N. Kriegisch
- Institute for Marine and Antarctic Studies University of Tasmania, 20 Castray Esplanade, Battery Point Tasmania Australia
| | - C. R. Johnson
- Institute for Marine and Antarctic Studies University of Tasmania, 20 Castray Esplanade, Battery Point Tasmania Australia
| | - S. D. Ling
- Institute for Marine and Antarctic Studies University of Tasmania, 20 Castray Esplanade, Battery Point Tasmania Australia
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5
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Graham TDJ, Morris RL, Strain EMA, Swearer SE. Identifying key factors for transplantation success in the restoration of kelp (
Ecklonia radiata
) beds. Restor Ecol 2021. [DOI: 10.1111/rec.13536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Tristan D. J. Graham
- National Centre for Coasts and Climate (NCCC), School of BioSciences University of Melbourne Parkville Victoria 3010 Australia
| | - Rebecca L. Morris
- National Centre for Coasts and Climate (NCCC), School of BioSciences University of Melbourne Parkville Victoria 3010 Australia
| | - Elisabeth M. A. Strain
- National Centre for Coasts and Climate (NCCC), School of BioSciences University of Melbourne Parkville Victoria 3010 Australia
| | - Stephen E. Swearer
- National Centre for Coasts and Climate (NCCC), School of BioSciences University of Melbourne Parkville Victoria 3010 Australia
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6
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Sharma R, Swearer SE, Morris RL, Strain EMA. Testing the efficacy of sea urchin exclusion methods for restoring kelp. MARINE ENVIRONMENTAL RESEARCH 2021; 170:105439. [PMID: 34365122 DOI: 10.1016/j.marenvres.2021.105439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 06/13/2023]
Abstract
Kelps are ecosystem engineers, which collectively form forests that provide a variety of important ecosystem services for humans and other organisms. Kelp forests are threatened by multiple local and global stressors, one of the most notable is herbivory. Overabundant sea; urchins can consume kelp, leading to a phase shift from productive forests to unproductive; rocky barrens. Reducing sea urchin densities by directly removing them can reverse this; phase shift. However, maintaining low densities of sea urchins, is logistically and financially; challenging. Following a review of herbivore exclusion methods to date, we tested the efficacy of three different methods for excluding sea urchins from kelp in the laboratory: flexible fences; electricity; and copper anti-fouling paint. The results from the laboratory; experiment showed that flexible fencing was the most successful method for excluding sea urchins. To test the efficacy of this method in the field, sea urchins were removed from 1m2 patches in barrens and intact kelp beds, and the effectiveness of flexible fences of two different heights (30 cm and 60 cm) at excluding sea urchins were tested. The results from the field study demonstrated that flexible fences of both heights were effective at maintaining low sea urchin densities in barrens but not in intact kelp beds, relative to unmanipulated; rocky barrens. These findings suggest that flexible fencing could be an important tool in restoring kelp in barrens, however the costs of fencing are likely to place limits on the scale at which this management strategy can be implemented.
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Affiliation(s)
- Rituraj Sharma
- National Centre for Coasts and Climate, University of Melbourne, VIC, 3010, Australia.
| | - Stephen E Swearer
- National Centre for Coasts and Climate, University of Melbourne, VIC, 3010, Australia
| | - Rebecca L Morris
- National Centre for Coasts and Climate, University of Melbourne, VIC, 3010, Australia
| | - Elisabeth M A Strain
- National Centre for Coasts and Climate, University of Melbourne, VIC, 3010, Australia; Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, TAS, 7001, Australia.
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7
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Suebsanguan S, Strain EMA, Morris RL, Swearer SE. Optimizing the initial cultivation stages of kelp
Ecklonia radiata
for restoration. Restor Ecol 2021. [DOI: 10.1111/rec.13388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sarucha Suebsanguan
- National Centre for Coasts and Climate and School of BioSciences University of Melbourne Melbourne Victoria 3010 Australia
| | - Elisabeth M. A. Strain
- National Centre for Coasts and Climate and School of BioSciences University of Melbourne Melbourne Victoria 3010 Australia
- Institute for Antarctic and Marine Science University of Tasmania Hobart Tasmania 7004 Australia
| | - Rebecca L. Morris
- National Centre for Coasts and Climate and School of BioSciences University of Melbourne Melbourne Victoria 3010 Australia
| | - Stephen E. Swearer
- National Centre for Coasts and Climate and School of BioSciences University of Melbourne Melbourne Victoria 3010 Australia
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8
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Barrett LT, Dempster T, Swearer SE. A nonnative habitat-former mitigates native habitat loss for endemic reef fishes. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01956. [PMID: 31219635 DOI: 10.1002/eap.1956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/17/2019] [Accepted: 05/28/2019] [Indexed: 06/09/2023]
Abstract
Animals that select the best available habitats are most likely to succeed in degraded environments, but ecological change can create evolutionarily unfamiliar habitats that may be under- or over-utilized by native fauna. In temperate coastal waters, eutrophication and grazing have driven a global decline in native seaweeds and facilitated the establishment of nonnative seaweeds that provide novel macrophyte habitat. We tested whether a nonnative kelp canopy (wakame Undaria pinnatifida) functions as a viable habitat or ecological trap for several endemic reef fishes on urchin-grazed reefs in southern Australia. We assessed the willingness of fish to utilize native vs. wakame kelp canopy via a laboratory habitat choice experiment and by recording natural recruitment to specially constructed boulder reefs with manipulated kelp canopy. We also compared fish communities on natural reefs using a before-after-control-impact survey of wakame patches, and to assess the quality of wakame habitat for resident fish, compared fitness metrics for fish collected from habitats with native vs. wakame kelp canopy. Endemic fishes did not distinguish between the native or wakame canopy but preferred both to barren reef habitats. On urchin-grazed natural reefs, fish occurred in higher abundance and diversity where seasonal wakame canopy was present. Fitness metrics in fish collected from wakame patches were comparable to those in fish from adjacent native kelp patches. These findings indicate that the nonnative canopy provides a viable habitat for endemic fish and may play a role in sustaining native fauna populations in this degraded ecosystem. More broadly, we recommend that managers consider the role of nonnative habitats within the context of environmental change, as endemic fauna may benefit from nonnative habitat-formers in areas where their native counterparts cannot persist.
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Affiliation(s)
- Luke T Barrett
- School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Tim Dempster
- School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Stephen E Swearer
- School of BioSciences, University of Melbourne, Parkville, Victoria, 3010, Australia
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9
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Kriegisch N, Reeves SE, Flukes EB, Johnson CR, Ling SD. Drift-kelp suppresses foraging movement of overgrazing sea urchins. Oecologia 2019; 190:665-677. [PMID: 31250188 DOI: 10.1007/s00442-019-04445-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 06/25/2019] [Indexed: 10/26/2022]
Abstract
Sea urchins have the capacity to destructively overgraze kelp beds and cause a wholesale shift to an alternative and stable 'urchin barren' reef state. However, destructive grazing appears labile and contingent on behavioural shift. Changes in supply of allochthonous 'drift-kelp' food are hypothesised as a trigger of change in urchin grazing behaviour, yet field tests are lacking. Here we conduct a suite of in situ behavioural surveys and manipulative experiments within kelp beds and on urchin barrens to examine foraging movements and evidence for a behavioural switch to an 'overgrazing mode' by the Australian urchin Heliocidaris erythrogramma (Echinometridae). Tracking urchins using time-lapse photography revealed urchin foraging to conform to a random walk model within kelp beds and on barrens. However, many individuals tended towards local movement within proximal crevices and movement was reduced in kelp beds compared to barrens. Directional movement of urchins toward newly available kelp was experimentally inducible, consistent with locally observed 'mobile-feeding-fronts' that develop at barrens-kelp interfaces. Habitat-specific feeding modes were also evidenced by herbivory assays which revealed urchin grazing rates to be high on both drift-kelp and standing kelp on barren grounds, while drift-kelp but not standing kelp was consumed at high rates within kelp beds. Time-lapse tracking of urchin foraging before/after addition of drift-kelp revealed a reduction in foraging across the reef surface after drift-kelp capture. Collectively, results indicate that the availability of drift-kelp is a pivotal trigger in determining urchin feeding modes which thus mediates the shift between alternative stable states for rocky reef ecosystems.
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Affiliation(s)
- N Kriegisch
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, TAS, 7004, Australia
| | - S E Reeves
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, TAS, 7004, Australia
| | - E B Flukes
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, TAS, 7004, Australia
| | - C R Johnson
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, TAS, 7004, Australia
| | - S D Ling
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, TAS, 7004, Australia.
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10
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Ling SD, Kriegisch N, Woolley B, Reeves SE. Density-dependent feedbacks, hysteresis, and demography of overgrazing sea urchins. Ecology 2019; 100:e02577. [PMID: 30707451 DOI: 10.1002/ecy.2577] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 09/13/2018] [Accepted: 10/08/2018] [Indexed: 01/10/2024]
Abstract
Sea urchin grazing can result in regime shift from productive kelp beds to sea urchin barren grounds that represent an alternative and stable reef state. Here we examine the stability of urchin barrens by defining the demographics of the Australian urchin Heliocidaris erythrogramma during regime shift to, and maintenance of, barrens. Inverse-logistic modeling of calibrated in situ annual growth increments for five urchin populations, two from kelp beds and three from barrens, demonstrate slowing of urchin growth as availability and consumption of standing and/or drift kelp declines. Population age structures were predicted from observed sizes over four years (2012-2015, n = 5,864 individuals), which indicated stable age distributions for populations both maintaining barrens and actively grazing among kelp beds. Younger age distributions occurred on barrens whereas more mature populations existed within kelp beds, indicating that high recruitment facilitates maintenance of barrens while overgrazing appeared more reliant on adult urchins grazing from the edges of kelp beds, as opposed to juvenile recruitment among kelp. Leslie-matrix projections indicated potential for unchecked population growth for all study populations, but which varied depending on whether local or regional recruitment rates were modeled. Ultimately, strong density dependence was observed to check population growth; with high-recruitment/high-density populations offset by reduced growth rates and decreased longevity. Increasing disease rates among older urchins in high-density populations were consistent with observed density-dependent mortality, while tethering of healthy urchins revealed highest predation on small urchins within kelp beds, suggesting some remnant resilience of declining kelp habitat. Results demonstrate that the greatest opportunity for urchin population control is when reefs exist in the kelp bed state, at which point urchin populations are prone to negative feedback. Conversely, control of urchins on barrens is demonstrably difficult given positive density-dependent feedbacks that act to stabilize population size and which evidently underpin the hysteresis effect governing the persistence of this alternative stable state.
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Affiliation(s)
- S D Ling
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - N Kriegisch
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - B Woolley
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - S E Reeves
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, 7001, Australia
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11
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Reeves SE, Kriegisch N, Johnson CR, Ling SD. Reduced resistance to sediment-trapping turfs with decline of native kelp and establishment of an exotic kelp. Oecologia 2018; 188:1239-1251. [PMID: 30406820 DOI: 10.1007/s00442-018-4275-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 10/14/2018] [Indexed: 10/27/2022]
Abstract
Understanding the strength and type of interactions among species is vital to anticipate how ecosystems will respond to ongoing anthropogenic stressors. Here, we examine the ecological function of native (Ecklonia radiata) and invasive (Undaria pinnatifida) kelps in resisting shifts to sediment-trapping turf on reefs within the highly urbanized temperate Port Phillip Bay (PPB), Australia. Short-term (30 days) and long-term (232 days) manipulations demonstrated that kelp laminae can clear and maintain the substratum free of turfs, while conversely, removal of kelp leads to a proliferation of turfs. Analyses looking at the relationship between total length of E. radiata and U. pinnatifida and the area cleared of turf algae showed that the clearing effect of E. radiata over a year was greater than that of U. pinnatifida due to the annual die-back of the invasive. A natural experiment (608 days) identified that ongoing sea urchin (Heliocidaris erythrogramma) grazing led to native kelp bed decline, facilitating turf dominance. Even though U. pinnatifida establishes once native beds are disturbed, its ecological function in clearing turf is weaker than E. radiata, given its annual habit. In PPB, turfs represent the more persistent and problematic algal group and are likely changing the structure, function, and energy flows of shallow temperate reefs in this urbanised embayment.
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Affiliation(s)
- S E Reeves
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, Hobart, TAS, 7004, Australia.
| | - N Kriegisch
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, Hobart, TAS, 7004, Australia
| | - C R Johnson
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, Hobart, TAS, 7004, Australia
| | - S D Ling
- Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, Hobart, TAS, 7004, Australia
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12
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Ling SD, Davey A, Reeves SE, Gaylard S, Davies PL, Stuart-Smith RD, Edgar GJ. Pollution signature for temperate reef biodiversity is short and simple. MARINE POLLUTION BULLETIN 2018; 130:159-169. [PMID: 29866542 DOI: 10.1016/j.marpolbul.2018.02.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 02/24/2018] [Accepted: 02/24/2018] [Indexed: 06/08/2023]
Abstract
Pollution increasingly impacts healthy functioning of marine ecosystems globally. Here we quantify concentrations of major pollutant types (heavy metals/sewage/petrochemicals/plastics) as accumulated within marine sediments on and/or immediately adjacent to shallow reefs for 42 sites spanning coastal population centres across south-eastern Australia. Gradients in pollutants were revealed, but few pollutants co-varied, while increasing wave exposure ostensibly diluted concentrations of all pollutants except microplastics. Examination of reef biodiversity indicators revealed that maximum size of fauna and flora, a key life-history parameter summarised by the Community shortness index, plus declining functional and species richness, were the most sensitive bioindicators of pollutants - for which heavy metals and nutrient-enrichment were most pervasive. Results indicate that assemblages of biogenic habitat formers and associated fauna collapse from "long and complicated" to "short and simplified" configurations in response to increasing pollution, and this community signature may form an effective bioindicator to track human-driven degradation.
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Affiliation(s)
- S D Ling
- Institute for Marine & Antarctic Studies, University of Tasmania, Hobart 7001, Australia.
| | - A Davey
- Institute for Marine & Antarctic Studies, University of Tasmania, Hobart 7001, Australia
| | - S E Reeves
- Institute for Marine & Antarctic Studies, University of Tasmania, Hobart 7001, Australia
| | - S Gaylard
- Environment Protection Authority, 250 Victoria Square, Adelaide, South Australia 5000, Australia
| | - P L Davies
- New South Wales Office of Environment and Heritage, 59-61 Goulburn Street, Sydney, NSW 2001, Australia
| | - R D Stuart-Smith
- Institute for Marine & Antarctic Studies, University of Tasmania, Hobart 7001, Australia
| | - G J Edgar
- Institute for Marine & Antarctic Studies, University of Tasmania, Hobart 7001, Australia
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