Macroalgae Practices

A healthy macroalgae forest

Restored Species: the macroalgae Sargassum sp.

IMG_9476

Main Stressor: the sea urchin

Diadema africanum

Practices for Macroalgae Restoration

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Assessment Phase
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Planning and Design Phase
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Implementation Phase
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Monitoring and Evaluation Phase
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Stakeholder Engagement
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Assessment Phase

Assess historical presence

  • Evaluate macroalgae forests for restoration potential

Identify potential donor populations

  • Availability, abundance, and location of potential donor populations will influence/determine restoration strategies and methods

Consider stressors

  • Examples: Eutrophication, overgrazing, impacts of urbanization

Evaluate habitat suitability

  • Examples: Depth, substrate, turbidity 1
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Planning and Design Phase

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Select donor populations as close as possible to the restoration site 1

Select donors from comparable environments

Create a plan to mitigate or eliminate stressors 2

Align restoration with reproductive season

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Implementation Phase

Weigh the pros and cons of in situ vs ex-situ techniques

Choose techniques considering the following factors

  1. Availability of culture resources
  2. Costs, labour, and energy required in culture facilities and related activites
  3. Minimum culture duration
  4. Dispersal capacity of the target species
  5. Hydrodynamic regime of selected site
  6. Grazing pressures
  7. Other pressures pertinent to the site
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Monitoring and Evaluation Phase

Utilize appropriate indicators

Examples: Population extent, density of cover of the species, presence of fertile individuals, population size structure, biodiversity 7, 14, 15, 16, 17, 18, 19, 20, 21, 22

Complete thorough sampling

Conducted over a short period of time in comparison to a control site 1

Length of monitoring, rigourous short term (5 years) with plan to conduct long term (10-15 years)1

2 keys types of monitoring to utilize

    • Progress of activities: Survival, extent, cover, and density of species
    • Benefits of overall success: Fauna, food webs, water quality, other relevant factors 

Success focuses on reproduction of species, increase of algae cover, and transplanted algae survival

Success measures should encompass first reproductive cycle of restored individuals 7

Successful Example

A healthy macroalgae forest
A healthy macroalgae forest

Non-Successful Example

<em> A sea-urchin barren
A sea-urchin barren
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Stakeholder Engagement

Plan the timing of engagement for each stakeholder group to engage them in appropriate parts of the project

Create volunteer opportunities for local community to participate in monitoring and upkeep of the site

Engage, collaborate, and create networks to secure legal, financial, and community support

Useful Contacts

Susanne Schäfer

susi

MARE Madeira/Arditi

João Monteiro

joao

MARE Madeira/Arditi

Demetris Kletou

Screenshot 2025-07-25 at 16.43.22

MERE Research

References

1. Smith CJ, Verdura J, Papadopoulou N, Fraschetti S, Cebrian E, Fabbrizzi E, Monserrat M, Drake M, Bianchelli S, Danovaro R, Malak DA, Ballesteros E, Benjumea Tesouro T, Boissery P, D’Ambrosio P, Galobart C, Javel F, Laurent D, Orfanidis S, Mangialajo L (2023) A decision-support framework for the restoration of Cystoseira sensu lato forests. Frontiers in Marine Science, 10:1159262. https://doi.org/10.3389/fmars.2023.1159262
2. Iveša L, Djakovac T, Devescovi M (2016) Long-term fluctuations in Cystoseira populations along the west Istrian Coast (Croatia) related to eutrophication patterns in the northern Adriatic Sea. Marine Pollution Bulletin, 106:162–173. https://doi.org/10.1016/j.marpolbul.2016.03.010
3. Filbee-Dexter K, Wernberg T (2018) Rise of turfs: A new battlefront for globally declining kelp forests. BioScience, 68:64–76.
4. Layton C, Coleman MA, Marzinelli EM, Steinberg PD, Swearer SE, Vergés A, Wernberg T, Johnson CR (2020) Kelp forest restoration in Australia. Frontiers in Marine Science, 7:2020.
5. Thomsen MS, Wernberg T, Altieri AH, Tuya F, Gulbransen DJ, McGlathery KJ, Holmer M, Silliman BR (2010) Habitat cascades: The conceptual context and global relevance of facilitation cascades via habitat formation and modification. Integrative and Comparative Biology, 50:158–175. https://doi.org/10.1093/icb/icq042
6. Gorman D, Connell SD (2009) Recovering subtidal forests in human‐dominated landscapes. Journal of Applied Ecology, 46:1258–1265. https://doi.org/10.1111/j.1365-2664.2009.01711.x
7. Verdura J, Sales M, Ballesteros E, Cefalì ME, Cebrian E (2018) Restoring a canopy-forming alga based on recruitment enhancement: Methods and long-term success assessment. Frontiers in Plant Science, 9:2018. https://doi.org/10.3389/fpls.2018.01832
8. Campbell AH, Marzinelli EM, Vergés A, Coleman MA, Steinberg PD (2014) Towards restoration of missing underwater forests. PLOS ONE, 9:e84106. https://doi.org/10.1371/journal.pone.0084106
9. Wernberg T, Coleman MA, Bennett S, Thomsen MS, Tuya F, Kelaher BP (2018) Genetic diversity and kelp forest vulnerability to climatic stress. Scientific Reports, 8:2018. https://doi.org/10.1038/s41598-018-20009-9
10. Eger AM, Marzinelli EM, Hartvig C, Fagerli CW, Fujita D, Gonzalez AP, Woo Hong S, Ha Kim J, Lee LC, McHugh TA, Nishihara GN, Tatsumi M, Steinberg PD, Vergés A (2022) Global kelp forest restoration: Past lessons, present status, and future directions. Biological Reviews, 97:2022. https://doi.org/10.1111/brv.12850
11. Coleman MA, Wood G, Filbee-Dexter K, Minne AJP, Goold HD, Vergés A, Marzinelli EM, Steinberg PD, Wernberg T (2020) Restore or redefine: Future trajectories for restoration. Frontiers in Marine Science, 7:2020. https://doi.org/10.3389/fmars.2020.00237
12. Krause-Jensen D, Duarte CM (2016) Substantial role of macroalgae in marine carbon sequestration. Nature Geoscience, 9:737–742. https://doi.org/10.1038/ngeo2790
13. Vergés A, Doropoulos C, Malcolm HA, Skye M, Garcia-Pizá M, Marzinelli EM, Campbell AH, Ballesteros E, Hoey AS, Vila-Concejo AV, Bozec YM, Steinberg PD (2016) Long-term empirical evidence of ocean warming leading to tropicalization of fish communities, increased herbivory, and loss of kelp. PNAS, 113:13791–13796. https://doi.org/10.1073/pnas.1610725113
14. Gran A, Movilla J, Ballesteros E, Sales M, Bolado I, Galobart C, et al. (2022) Assessing the expansion and success of a restored population of Gongolaria barbata (Stackhouse) Kuntze (Fucales, Phaeophyceae) using high-precision positioning tools and size distribution frequencies. Mediterranean Marine Science, 23:907–916. https://doi.org/10.12681/mms.30500
15. Galobart C, Ballesteros E, Golo R, Cebrian E (2023) Addressing marine restoration success: Evidence of species and functional diversity recovery in a ten-year restored macroalgal forest. Frontiers in Marine Science, 10:1176655. https://doi.org/10.3389/fmars.2023.1176655
16. De La Fuente G, Chiantore M, Asnaghi V, Kaleb S, Falace A (2019) First ex situ outplanting of the habitat-forming seaweed Cystoseira amentacea var. stricta from a restoration perspective. PeerJ, 7:e7290. https://doi.org/10.7717/peerj.7290
17. Tamburello L, Papa L, Guarnieri G, Basconi L, Zampardi S, Scipione MB, et al. (2019) Are we ready for scaling up restoration actions? An insight from Mediterranean macroalgal canopies. PLOS ONE, 14:e0224477. https://doi.org/10.1371/journal.pone.0224477
18. Medrano A, Hereu B, Cleminson M, Pagès-Escolà M, Rovira G, Solà J, et al. (2020) From marine deserts to algal beds: Treptacantha elegans revegetation to reverse stable degraded ecosystems inside and outside a no-take marine reserve. Restoration Ecology, 28:632–644. https://doi.org/10.1111/rec.13123
19. Orlando-Bonaca M, Pitacco V, Slavinec P, Šiško M, Makovec T, Falace A (2021) First restoration experiment for Gongolaria barbata in Slovenian coastal waters. What can go wrong? Plants, 10:239. https://doi.org/10.3390/plants10020239
20. Savonitto G, de la Fuente G, Tordoni E, Ciriaco S, Srijemsi M, Bacaro G, et al. (2021) Addressing reproductive stochasticity and grazing impacts in the restoration of a canopy-forming brown alga by implementing mitigation solutions. Aquatic Conservation: Marine and Freshwater Ecosystems, 31:1611–1623. https://doi.org/10.1002/aqc.3555
21. Orlando-Bonaca M, Savonitto G, Asnaghi V, Trkov D, Pitacco V, Šiško M, et al. (2022) Where and how—new insight for brown algal forest restoration in the Adriatic. Frontiers in Marine Science, 9:988584. https://doi.org/10.3389/fmars.2022.988584
22. Clausing RJ, de la Fuente G, Falace A, Chiantore M (2023) Accounting for environmental stress in restoration of intertidal foundation species. Journal of Applied Ecology, 60:305–318. https://doi.org/10.1111/1365-2664.14334

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