Tohoku University - Iwani

Restoration Project

Tohoku University - Iwani

Restoration Objective:

This study tested the hypothesis that, in the Sea of Japan off southwestern Hokkaido, recruitment and production of Saccharina japonica and Saccharina religiosa are restricted by low nutrient concentration.

Site Selection Criteria:

The experiment was conducted in two small ports, with each nutrient-enhanced and natural site being about 0.5ha at a depth of 1.4m. The nutrient-enhanced and natural sites faced west and were separated by 0.2 km. Neither site was influenced by freshwater or domestic waste inflows. The bottom substrata at each site consisted of rocks (on which the growth of crustose coralline algae was predominant) surrounded on all sides by sand.

Cause Of Decline:

Large perennial brown algae belonging to the orders Laminariales (kelp) and Fucales (fucoids) dominate many intertidal and subtidal rocky shore environments in temperate and subarctic regions, and provide important habitats and nurseries to a wide range of species. Phase shifts between kelp forest and barren states are affected by the intensity of sea urchin herbivory which, in turn, is regulated by the abundance of vertebrate predators, disease, recruitment and climate change effects. In the Macrocystis pyrifera forests off California, low nutrient concentration during summer, coupled with above-average seawater temperatures, has resulted in canopy deterioration and failed recruitment of subtidal kelp species. In Japan, phase-shift alternations of kelp, between forest and barren states, have also been reported.

Key Reasons For Decline:

Unspecified

Scientific Paper

Enhancement of Saccharina kelp production by nutrient supply in the Sea of Japan off southwestern Hokkaido, Japan

Y. Agatsuma, H. Endo, S. Yoshida, C. Ikemori, Fujishima Takeuchi, K. Taniguchi
Journal of Applied Phycology, Vol. 26.
https://doi.org/10.1007/s10811-013-0196-z

Organisation:

Tohoku University

Site Observations:

Observation Date

1st Oct 2008 – 1st May 2009

Action Summary:

At two sites, hatchery-raised gametophytes of Saccharina japonica and wild Saccharina religiosa were cultivated on ropes and on concrete reefs. At one site, artificial nutrients was added continuously while at the other site it was not. At both sites, sea urchins (S. nudus, S. intermedius, and Hemicentrotus pulcherrimus) were removed on three occasions to exclude a top-down effect.

Lessons Learned:

This method aimed to tease apart the top-down effects of urchin control from the bottom-up effects of nutrient enhancement, and combined a variety of conservation methods (seeding, blocks, rope, culling and nutrients). Their results indicate Saccharina kelps may be nutrient limited in this area.

Project Outcomes:

At both sites, sea urchins were removed for exclusion of top–down effect. At the natural site, no hatchery-raised S. japonica and wild S. religiosa grew on the rope. No wild S. religiosa grew on the porous-concrete reefs and rocks. At the nutrient-enhanced site, S. japonica and S. religiosa grew rapidly on the rope, at rates of 47.7 and 33.3 plants/10 cm length rope, respectively. S. religiosa grew on the concrete reefs at a concentration of 9.7 plants/0.3 m2. At the nutrient enhanced site, the concentrations of NH4-N, NO3-N, NO2-N, and PO4-P ranged from 35.2–173.2, 2.1–10.9, 0.3–1.5, and 0.8–2.6 mol L1, respectively, being markedly higher than those at the natural site, where these nutrient concentrations were almost equal to the averages off Tomari. These results indicate that the production of Saccharina kelp is restricted by bottom–up effects (at a low nutrient concentration) in the Sea of Japan, southwestern Hokkaido.

Key Reasons For Decline:

Unspecified

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Wet Weight Kelp

0.0000
g WW/m2
0.0000
g WW/m2

Observation Date

1st Oct 2008 – 1st May 2009

Action Summary:

At two sites, hatchery-raised gametophytes of Saccharina japonica and wild Saccharina religiosa were cultivated on ropes and on concrete reefs. At one site, artificial nutrients was added continuously while at the other site it was not. At both sites, sea urchins (S. nudus, S. intermedius, and Hemicentrotus pulcherrimus) were removed on three occasions to exclude a top-down effect.

Lessons Learned:

This method aimed to tease apart the top-down effects of urchin control from the bottom-up effects of nutrient enhancement, and combined a variety of conservation methods (seeding, blocks, rope, culling and nutrients). Their results indicate Saccharina kelps may be nutrient limited in this area.

Project Outcomes:

At the site without nutrient enhancement, no hatchery-raised S. japonica or wild S. religiosa grew on installed ropes. No S. religiosa grew on the porous-concrete reefs and rocks. At the nutrient-enhanced site, S. japonica and S. religiosa grew rapidly on the rope, at rates of 47.7 and 33.3 plants/10cm length rope, respectively. S. religiosa grew on the concrete reefs at a concentration of 9.7 plants/0.3m2.

Key Reasons For Decline:

Unspecified

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Wet Weight Kelp

0.0000
g WW/m2
0.0000
g WW/m2
Transplant Info:
Source:Wild

Observation Date

1st Oct 2008 – 1st May 2009

Action Summary:

At two sites, hatchery-raised gametophytes of Saccharina japonica and wild Saccharina religiosa were cultivated on ropes and on concrete reefs. At one site, artificial nutrients was added continuously while at the other site it was not. At both sites, sea urchins (S. nudus, S. intermedius, and Hemicentrotus pulcherrimus) were removed on three occasions to exclude a top-down effect.

Lessons Learned:

This method aimed to tease apart the top-down effects of urchin control from the bottom-up effects of nutrient enhancement, and combined a variety of conservation methods (seeding, blocks, rope, culling and nutrients). Their results indicate Saccharina kelps may be nutrient limited in this area.

Project Outcomes:

At the site without nutrient enhancement, no hatchery-raised S. japonica or wild S. religiosa grew on installed ropes. No S. religiosa grew on the porous-concrete reefs and rocks. At the nutrient-enhanced site, S. japonica and S. religiosa grew rapidly on the rope, at rates of 47.7 and 33.3 plants/10cm length rope, respectively. S. religiosa grew on the concrete reefs at a concentration of 9.7 plants/0.3m2.

Key Reasons For Decline:

Unspecified

Area of Restoration (Ha)

0

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Wet Weight Kelp

31.6804
g WW/m2
0.0000
g WW/m2

Observation Date

1st Oct 2008 – 1st May 2009

Action Summary:

At two sites, hatchery-raised gametophytes of Saccharina japonica and wild Saccharina religiosa were cultivated on ropes and on concrete reefs. At one site, artificial nutrients was added continuously while at the other site it was not. At both sites, sea urchins (S. nudus, S. intermedius, and Hemicentrotus pulcherrimus) were removed on three occasions to exclude a top-down effect.

Lessons Learned:

This method aimed to tease apart the top-down effects of urchin control from the bottom-up effects of nutrient enhancement, and combined a variety of conservation methods (seeding, blocks, rope, culling and nutrients). Their results indicate Saccharina kelps may be nutrient limited in this area.

Project Outcomes:

At the site without nutrient enhancement, no hatchery-raised S. japonica or wild S. religiosa grew on installed ropes. No S. religiosa grew on the porous-concrete reefs and rocks. At the nutrient-enhanced site, S. japonica and S. religiosa grew rapidly on the rope, at rates of 47.7 and 33.3 plants/10cm length rope, respectively. S. religiosa grew on the concrete reefs at a concentration of 9.7 plants/0.3m2.

Key Reasons For Decline:

Unspecified

Area of Restoration (Ha)

0

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Wet Weight Kelp

192.1488
g WW/m2
0.0000
g WW/m2

Observation Date

1st Oct 2008 – 1st May 2009

Action Summary:

At two sites, hatchery-raised gametophytes of Saccharina japonica and wild Saccharina religiosa were cultivated on ropes and on concrete reefs. At one site, artificial nutrients was added continuously while at the other site it was not. At both sites, sea urchins (S. nudus, S. intermedius, and Hemicentrotus pulcherrimus) were removed on three occasions to exclude a top-down effect.

Lessons Learned:

This method aimed to tease apart the top-down effects of urchin control from the bottom-up effects of nutrient enhancement, and combined a variety of conservation methods (seeding, blocks, rope, culling and nutrients). Their results indicate Saccharina kelps may be nutrient limited in this area.

Project Outcomes:

At the site without nutrient enhancement, no hatchery-raised S. japonica or wild S. religiosa grew on installed ropes. No S. religiosa grew on the porous-concrete reefs and rocks. At the nutrient-enhanced site, S. japonica and S. religiosa grew rapidly on the rope, at rates of 47.7 and 33.3 plants/10cm length rope, respectively. S. religiosa grew on the concrete reefs at a concentration of 9.7 plants/0.3m2.

Key Reasons For Decline:

Unspecified

Area of Restoration (Ha)

0

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Wet Weight Kelp

199.0358
g WW/m2
0.0000
g WW/m2
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