Universita' di Trieste - Miramare MPA

Restoration Project

Universita' di Trieste - Miramare MPA

Restoration Objective:

Overall, this study aimed to evaluate the following:1. The effects of a thermal anomaly on the reproductive biology and performance in culture of G. barbata (the first phase of ex-situ restoration), and 2. the impact of fish grazing pressure on juveniles in the first, most critical, months following outplanting (the second phase of the exsitu restoration). The outcomes of these restoration efforts led to the implementation of mitigation solutions to overcome some of the bottlenecks in subtidal canopy-forming macroalgae restoration (i.e., reproductivity, stochasticity, and fish grazing) from the perspective of upscaling these restoration techniques.

Site Selection Criteria:

The restoration site was the Miramare MPA in Italy (45.701835, 13.714113), where G. barbata was once present (Bussani & Vukovic, 1992) but has not been observed in the last 20 years and only isolated thalli of C. compressa can be found (Falace,Di Pascoli & Bressan, 2005). The cultured germlings were outplanted in the ‘no-take’ area of the Miramare MPA (30 ha out of the total 120 ha), where human activities are prohibited.

Cause Of Decline:

In the last 4 decades, the decline of Cystoseira sensu lato (henceforth referred to as Cystoseira) (Fucales, Phaeophyceae) forests in the Mediterranean Sea has been widely documented (e.g. Munda, 1980;Munda, 1982; Hoffman et al., 1988; Munda, 1993a; Cormaci &Furnari, 1999; Thibaut et al., 2005; Mangialajo, Chiantore & Cattaneo-Vietti, 2008; Thibaut et al., 2015a; Thibaut et al., 2015b; Blanfunéet al., 2016; Valdazo et al., 2017; Mancuso et al., 2018) and has been mainly attributed to the interplay of several human impacts on the coastal environment, such as habitat destruction, pollution and over-grazing by sea urchins and herbivorous fish (e.g. Bellan-Santini, 1966;Arnoux & Bellan-Santini, 1972; Munda, 1974; Munda, 1982;Verlaque, 1987; Hoffman et al., 1988; Munda, 1993b; Chryssovergis& Panayotidis, 1995; Cormaci & Furnari, 1999; Benedetti-Cecchiet al., 2001; Soltan et al., 2001; Hereu, 2004; Sales &Ballesteros, 2009; Sales et al., 2011; Gianni et al., 2013; Pinedo,Zabala & Ballesteros, 2013; Strain et al., 2014).

Key Reasons For Decline:

Multiple

Scientific Paper

Addressing reproductive stochasticity and grazing impacts in the restoration of a canopy‐forming brown alga by implementing mitigation solutions

Savonitto, G., De La Fuente, G., Tordoni, E., Ciriaco, S., Srijemsi, M., Bacaro, G., ... & Falace, A. (2021).https://arts.units.it/handle/11368/2976299

Organisation:

Universita' di Trieste

Site Observations:

Observation Date

1st Apr 2019 – 1st Oct 2019

Action Summary:

Fertile apices of Gongolaria barbata were harvested and cultivated on clay tiles in mesocosms for one month prior to either transplantation to the restoration site or receiving an additional 3 months of suspended cultivation prior to transplantation. Half of the tiles were protected by mesh cages, and the total monitoring time following transfer to the open ocean was 6 months.

Fertile apices of Gongolaria barbata were harvested and cultivated on clay tiles (4.5 cm in diameter, with a 0.6-cm hole at the centre to screw the tile onto the outplanting modular support) in aerated aquaria containing Von Stosch's enriched filtered sea water and cultivated for 4 weeks under controlled conditions (18 °C temperature, 125 μmol photons m−2 s−1 light intensity, and a 15:9 h light:dark cycle).

The tiles were then transplanted to the restoration site and attached to previously assembled galvanized iron modular frames (0.5 m² surface area), with each frame having a capacity of 30 tiles; the seven frames together covered a total area of 3.5 m².

Lessons Learned:

Reproductive stochasticity associated with thermal anomalies represents a major challenge for large-scale restoration, highlighting the importance of monitoring phenological responses and potentially collecting prematurely fertile receptacles or selecting thermally tolerant lineages. Controlling for grazers was critical for improving juvenile survival and growth, although large-scale application may require management through trophic restoration or herbivore culling. The modular frame design also proved to be a highly time-efficient outplanting approach.

Project Outcomes:

Controlling for grazers improved the performance of the outplantings. After 6 months, the number of juveniles per tile ranged between one and two in both treatments, but, in the P treatment, the percentage of tiles with at least one juvenile was almost 2-fold that in the UP treatment. In addition, the juveniles were on average 2 times larger in the P treatment, and their length distribution resembled that of a natural population.

In this study, the second culture was less efficient than the first culture in terms of zygote release (10 times lower) and germling growth (four times shorter), despite both cultures being carried out under the same laboratory conditions. The natural variability in propagule release among fucoid species is well known (Gunnill, 1980; Reed, 1990; Vadas, Johnson & Norton, 1992); therefore, differences in the release efficiency could be expected. In this case, however, the MHW probably exacerbated this natural variability and affected germling growth as well. As it was already fertile in February, G.barbata was most likely to be at the end of its reproductive cycle in May, as also evidenced by the poor development of branches and receptacles compared to the usual spring phenology in the Gulf of Trieste (Falace & Zanelli, 2006).

Nature of Disturbance:

In February 2019, a MHW (+2.65C than the average monthly sea-surface temperature during the last 40 years) occurred in the northern Adriatic Sea, causing a phenological shift that abruptly triggered fertility in G. barbata at the donor site (Bevilacqua et al., 2019).

Area of Restoration (Ha)

0.00035

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

29.0000
%
100.0000
%
Transplant Info:
Life Stage:Juveniles
Source:Culture

Observation Date

1st Apr 2019 – 1st Oct 2019

Action Summary:

Fertile apices of Gongolaria barbata were harvested and cultivated on clay tiles in mesocosms for one month prior to either transplantation to the restoration site or receiving an additional 3 months of suspended cultivation prior to transplantation. Half of the tiles were protected by mesh cages, and the total monitoring time following transfer to the open ocean was 6 months.

Fertile apices of Gongolaria barbata were harvested and cultivated on clay tiles (4.5 cm in diameter, with a 0.6-cm hole at the centre to screw the tile onto the outplanting modular support) in aerated aquaria containing Von Stosch's enriched filtered sea water and cultivated for 4 weeks under controlled conditions (18 °C temperature, 125 μmol photons m−2 s−1 light intensity, and a 15:9 h light:dark cycle).

The tiles were then transplanted to the restoration site and attached to previously assembled galvanized iron modular frames (0.5 m² surface area), with each frame having a capacity of 30 tiles; the seven frames together covered a total area of 3.5 m². Grazing deterrents were formed by raising flexible metallic mesh strips around the tile, as petals of a flower.

Lessons Learned:

Reproductive stochasticity associated with thermal anomalies represents a major challenge for large-scale restoration, highlighting the importance of monitoring phenological responses and potentially collecting prematurely fertile receptacles or selecting thermally tolerant lineages. Controlling for grazers was critical for improving juvenile survival and growth, although large-scale application may require management through trophic restoration or herbivore culling. The modular frame design also proved to be a highly time-efficient outplanting approach.

Project Outcomes:

Controlling for grazers improved the performance of the outplantings. After 6 months, the number of juveniles per tile ranged between one and two in both treatments, but, in the P treatment, the percentage of tiles with at least one juvenile was almost 2-fold that in the UP treatment. In addition, the juveniles were on average 2 times larger in the P treatment, and their length distribution resembled that of a natural population.

In this study, the second culture was less efficient than the first culture in terms of zygote release (10 times lower) and germling growth (four times shorter), despite both cultures being carried out under the same laboratory conditions. The natural variability in propagule release among fucoid species is well known (Gunnill, 1980; Reed, 1990; Vadas, Johnson & Norton, 1992); therefore, differences in the release efficiency could be expected. In this case, however, the MHW probably exacerbated this natural variability and affected germling growth as well. As it was already fertile in February, G.barbata was most likely to be at the end of its reproductive cycle in May, as also evidenced by the poor development of branches and receptacles compared to the usual spring phenology in the Gulf of Trieste (Falace & Zanelli, 2006).

Nature of Disturbance:

In February 2019, a MHW (+2.65C than the average monthly sea-surface temperature during the last 40 years) occurred in the northern Adriatic Sea, causing a phenological shift that abruptly triggered fertility in G. barbata at the donor site (Bevilacqua et al., 2019)

Area of Restoration (Ha)

0.00033

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

46.0000
%
100.0000
%
Transplant Info:
Life Stage:Juveniles
Source:Culture

Observation Date

1st Sep 2019 – 1st Dec 2019

Action Summary:

Fertile apices of Gongolaria barbata were harvested and cultivated on clay tiles in mesocosms for one month prior to either transplantation to the restoration site or receiving an additional 3 months of suspended cultivation prior to transplantation. Half of the tiles were protected by mesh cages, and the total monitoring time following transfer to the open ocean was 6 months.

Fertile apices of Gongolaria barbata were harvested and cultivated on clay tiles (4.5 cm in diameter, with a 0.6-cm hole at the centre to screw the tile onto the outplanting modular support) in aerated aquaria containing Von Stosch's enriched filtered sea water and cultivated for 4 weeks under controlled conditions (18 °C temperature, 125 μmol photons m−2 s−1 light intensity, and a 15:9 h light:dark cycle). After 4 weeks of culture, the tiles were transported to the Miramare MPA, where they were affixed to a one-level plastic lantern net (55 cm diameter) suspended at 3 m depth.

The tiles were then moved to the rocky bottom after being attached to previously assembled galvanized iron modular frames (0.5 m² surface area), with each frame having a capacity of 30 tiles. Grazing deterrents were formed by raising flexible metallic mesh strips around the tile, as petals of a flower.

Lessons Learned:

Reproductive stochasticity associated with thermal anomalies represents a major challenge for large-scale restoration, highlighting the importance of monitoring phenological responses and potentially collecting prematurely fertile receptacles or selecting thermally tolerant lineages. Controlling for grazers was critical for improving juvenile survival and growth, although large-scale application may require management through trophic restoration or herbivore culling. The modular frame design also proved to be a highly time-efficient outplanting approach.

Project Outcomes:

Controlling for grazers improved the performance of the outplantings. After 6 months, the number of juveniles per tile ranged between one and two in both treatments, but, in the P treatment, the percentage of tiles with at least one juvenile was almost 2-fold that in the UP treatment. In addition, the juveniles were on average 2 times larger in the P treatment, and their length distribution resembled that of a natural population.

In this study, the second culture was less efficient than the first culture in terms of zygote release (10 times lower) and germling growth (four times shorter), despite both cultures being carried out under the same laboratory conditions. The natural variability in propagule release among fucoid species is well known (Gunnill, 1980; Reed, 1990; Vadas, Johnson & Norton, 1992); therefore, differences in the release efficiency could be expected. In this case, however, the MHW probably exacerbated this natural variability and affected germling growth as well. As it was already fertile in February, G.barbata was most likely to be at the end of its reproductive cycle in May, as also evidenced by the poor development of branches and receptacles compared to the usual spring phenology in the Gulf of Trieste (Falace & Zanelli, 2006).

Nature of Disturbance:

In February 2019, a MHW (+2.65C than the average monthly sea-surface temperature during the last 40 years) occurred in the northern Adriatic Sea, causing a phenological shift that abruptly triggered fertility in G. barbata at the donor site (Bevilacqua et al., 2019)

Area of Restoration (Ha)

0.00025

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Length

2.9000
m
1.2000
m
Transplant Info:
Life Stage:Juveniles
Source:Culture
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