University of Genoa - Punta Mesco

Restoration Project

University of Genoa - Punta Mesco

Restoration Objective:

We tested methods to improve restoration success of the intertidal forest-forming macroalga Ericaria amentacea (previously Cystoseira amentacea var. stricta) by enhancing resilience of lab-cultured juveniles to environmental stress in the habitat to be restored. We asked if juvenile post-outplant success could be enhanced by repeated exposure to mild stress in culture (fluctuations in irradiance, periodic increases in temperature) combined with methods to reduce physical stress in the target habitat (height on shore, artificial shading). We evaluated direct effects of experimental treatments on survival and growth as well as indirect effects that may result from different degrees of juvenile clumping on the outplant substrate. We hypothesized that reduced stress exposure in the habitat would increase survival, that environmental variability in culture would elevate growth, and that regardless of culture treatment, clumped juveniles would perform better than dispersed juveniles.

Site Selection Criteria:

The site of ex situ outplanting was located within the most protected zone of the Cinque Terre MPA (44° 8′2.95″N-9°38′10.10″E; Punta Mesco). The disappearance of historical E. amentacea forest from Cinque Terre in the early 20th century (De La Fuente et al., 2018) has been attributed to water pollution and sediment loads associated with heavy excavation in the watershed of the largest local riverine outflow (Magra River, ~25 km). The reduction of excavation activities several decades ago has restored water quality, and the establishment of the MPA in 1997 has further removed direct human stressors from the system (see Appendix S1). Nonetheless, the area remains devoid of E. amentacea and is dominated by mixed coralline algal turf and fragmented belts of a more tolerant fucoid alga, Cystoseira compressa. Both sites are characterized by a small tidal range (<30 cm) that is strongly influenced by barometric pressure, currents and significant swell. The native intertidal habitat of E. amentacea is characterized by high physical stress (predominantly light and temperature during the summer recruitment period) that is moderated by wave splash and changes in sea level associated with atmospheric pressure. Work was conducted within the framework of the EU-Life project, ROCPOP-Life (LIFE16 NAT/IT/000816), a restoration initiative for E. amentacea based on outplanting of ex situ cultured juveniles.

Cause Of Decline:

The disappearance of historical E. amentacea forest from Cinque Terre in the early 20th century (De La Fuente et al., 2018) has been attributed to water pollution and sediment loads associated with heavy excavation in the watershed of the largest local riverine outflow (Magra River, ~25 km). The reduction of excavation activities several decades ago has restored water quality, and the establishment of the MPA in 1997 has further removed direct human stressors from the system (see Appendix S1). Nonetheless, the area remains devoid of E. amentacea and is dominated by mixed coralline algal turf and fragmented belts of a more tolerant fucoid alga, Cystoseira compressa.

Key Reasons For Decline:

Water Pollution

Scientific Paper

Accounting for environmental stress in restoration of intertidal foundation species

Clausing, R. J., De La Fuente, G., Falace, A., & Chiantore, M. (2023).https://besjournals.onlinelib...full/10.1111/1365-2664.14334

Organisation:

University of Genoa

Site Observations:

Observation Date

1st Jul 2019 – 7th Nov 2019

Action Summary:

Following one month of laboratory cultivation, clay tiles with E. amentacea juveniles were outplanted in both the upper and lower tidal zones and monitored for four months.

Juveniles were cultured under four laboratory treatments combining stable/normal or variable light conditions with stable/normal temperature or periodic heat pulses. These treatments were used to test whether exposure to mild environmental stress during culture influenced post-outplant survival and growth. Clay tiles were outplanted in both the upper and lower tidal zones by affixing the tiles to the rock using anchors, screws, and neoprene washers inserted into pre-drilled holes. Half of the tiles received a shade treatment consisting of a ~5 cm diameter cylinder of 10 mm plastic mesh with open sides to minimise effects on water flow while allowing herbivore access.

Lessons Learned:

Restoration success was higher in the lower tidal zone, with clumped outplanting and mild stress exposure during culture increasing survival and growth.

Project Outcomes:

First, we found that the absence of adult canopy inhibits recruit re-establishment in the upper tidal zone that undisturbed native stands occupy. This implies that self-facilitation expands the realized niche of E. amentacea into zones of physical exposure beyond its fundamental niche and that restoration can only be achieved by targeting zones of lower stress for initial repopulation or by effectively reducing stress in the target habitat.

Second, the evidence that clustering of E. amentacea propagules on the outplant substrate provides self-facilitative benefits for repopulation supports calls to integrate positive feedbacks into restoration strategies for foundation species (Silliman et al., 2015; Valdez et al., 2020) and implies that consideration of multiple scales may be necessary (adult-recruit, recruit-recruit).

Finally, evidence of enhanced resilience through mild, variable stress exposure in culture highlights the potential for methods of selective breeding to increase adaptation to the target environment (sensu “directional selection” Coleman & Wernberg, 2020).

Area of Restoration (Ha)

0.00002

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

33.0000
%
100.0000
%
Transplant Info:
Life Stage:Juveniles
Source:Culture
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