Plant Assessment Form

Undaria pinnatifida

Common Names: Japanese kelp; wakame; Asian seaweed

Evaluated on: 4/7/05

List committee review date: 08/07/2005

Re-evaluation date:

Evaluator(s)

Gina Skurka
Cal-IPC
510-843-3902
gmskurka@cal-ipc.org
Joseph DiTomaso
University of California-Davis
Dept. Plant Sci., Mail Stop 4, Davis, CA 95616
530-754-8715
jmditomaso@ucdavis.edu

List commitee members

Carla Bossard
John Randall
Carri Pirosko
Dan Gluesenkamp
Gina Skurka
Brianna Richardson

General Comments

Gina contacted several people but was unable to obtain good information on current rate of spread of California populations.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 3.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes D Reviewed Scientific Publication
Impact?
Four-part score DCDU Total Score
C
1.2 ?Impact on plant community C. Minor Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels D. Negligible Reviewed Scientific Publication
1.4 ?Impact on genetic integrity U. Unknown
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Reviewed Scientific Publication
Invasiveness?
Total Points
15 Total Score B
2.2 ?Local rate of spread with no management B. Increases less rapidly Other Published Material
2.3 ?Recent trend in total area infested within state B. Increasing less rapidly Other Published Material
2.4 ?Innate reproductive potential
(see Worksheet A)
B. Moderate Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal A. High Reviewed Scientific Publication
2.6 ? Potential for natural long-distance dispersal A. Frequent Anecdotal
2.7 ?Other regions invaded C. Already invaded Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Reviewed Scientific Publication
Distribution?
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Reviewed Scientific Publication

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? D Reviewed Scientific Publication
Identify ecosystem processes impacted:

Our three year study of low shore assemblages in a sheltered New Zealand harbour has provided no evidence of significant ecological impacts from invasion of Undaria


Sources of information:

Forrest, B.M. and M.D. Taylor. 2002. Assessing invasion impact: survey design considerations and implications for management of an invasive marine plant. Biological Invasions. 4: 375-386.


Question 1.2 Impact on plant community composition,
structure, and interactions?
C Reviewed Scientific Publication
Identify type of impact or alteration:

An annual that apparently cannot compete well with large perennial brown algae, and is inhibited from establishing dense populations amongst natural kelp beds. A significant decrease in the surface covered by other species has been observed both in shallow and deeper areas during the period of max development of Undaria. In addition, a recent study provided evidence that indigenous species did not decrease in spring where Undaria was absent. Studies show no evidence of displacement of native algae, but showed that, in Tasmania, Undaria sporophytes established at high densities in plots from which the canopy of native algae was removed. The weight of evidence overall suggested little impact from Undaria on low shore assemblages, with control-impact contrasts that could plausibly be interpreted as impacts probably reflecting natural causes. There was no evidence for displacement of the native canopy by Undaria, with planned contrasts of percent cover between the controls and each of the infested sites largely suggesting a "no impact" result. The increased canopy cover resulting from Undaria's infestation could enhance sub-canopy low shore algal populations by providing greater shelter from dessication at low tide, as has been discussed in other studies.


Sources of information:

Edgar, G.J., N.S. Barrett, A.J. Morton, and C.R. Samson. 2004. Effects of algal canopy clearance on plant, fish and macroinvertebrate communities on eastern Tasmanian reefs. J Exp Mar Bio and Eco. 312: 67 - 87.
Curiel, D. P. Guidetti, B. Bellemo, M. Scattolin, and M Marzocchi. The introduced alga Undaria pinnatifida in the lagoon of Venice. Hydrobiologia. 477 1 June, 2002. 209-219.
Valentine, J.P. and C.R. Johnson. 2004. Establishment of the introduced kelp Undaria pinnatifida following dieback of the native macroalga Phyllospora comosa in Tasmania, Australia. Marine and Freshwater Research, 2004, 55, 223-230.
Forrest, B.M. and M.D. Taylor. 2002. Assessing invasion impact: survey design considerations and implications for management of an invasive marine plant. Biological Invasions. 4: 375-386.


Question 1.3 Impact on higher trophic levels? D Reviewed Scientific Publication
Identify type of impact or alteration:

Our three year study of low shore assemblages in a sheltered New Zealand harbour has provided no evidence of significant ecological impacts from invasion of Undaria.
Both Undaria's population dynamics and its effects upon native communities have been found to vary greatly among invaded areas.


Sources of information:

Forrest, B.M. and M.D. Taylor. 2002. Assessing invasion impact: survey design considerations and implications for management of an invasive marine plant. Biological Invasions. 4: 375-386.


Question 1.4 Impact on genetic integrity? U

Sources of information:

Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
B Other Published Material
Describe role of disturbance:

An annual that apparently cannot compete well with large perennial brown algae, and is inhibited from establishing dense populations amongst natural kelp beds. Undaria exhibited the only pronounced response to canopy removal amongst algal taxa, with a fivefold increase in cleared blocks compared to control blocks. Marine reserves are suggested to assist reef communities resist invasion by Undaria trough an indirect mechanism involving increased predation pressure on sea urchins and reduced formation of urchin barrens that are amenable to Undaria propagation. Disturbance events important for successful establishment of Undaria at high densities. In the absence of distrubance to the canopy, stands of native algae resisted development of Undaria sporophytes. Undaria occurs at high densites only in disturbed habitats, particularly on sea urchin barrens and also on areas of sand-scour at the edge of rocky reffs and on unstable substrata, but it occurs rarely in established native algal commmunities. The results from the present study highlight the opportunistic nature of Undaria. If intense disturbance occurs at an appropriate frequency it can be expected that Undaria will maintain large and persistent populations.


Sources of information:

Edgar, G.J., N.S. Barrett, A.J. Morton, and C.R. Samson. 2004. Effects of algal canopy clearance on plant, fish and macroinvertebrate communities on eastern Tasmanian reefs. J Exp Mar Bio and Eco. 312: 67 - 87.
Valentine, J.P. and C.R. Johnson. 2004. Establishment of the introduced kelp Undaria pinnatifida following dieback of the native macroalga Phyllospora comosa in Tasmania, Australia. Marine and Freshwater Research, 2004, 55, 223-230.


Question 2.2 Local rate of spread with no management? B Other Published Material
Describe rate of spread:

Eradication project underway in Monterey Bay.
Santa Barbara populations had large recruitment pulse in 2002 in conjunction with a drop in ocean temperature, but recruitment was low in 2001.


Sources of information:

Von Bubnoff, A. 2005. Seaweed eradication effort working. Monterey Herald. March 14, 2005. Accessed: www.montereyherald.com


Question 2.3 Recent trend in total area infested within state? B Other Published Material
Describe trend:

In CA, Undaria has been reported from at least 6 sites along the coast including Monterey harbor, Santa Barbara harbor, Channel Island harbor (Ventura), Oxnard harbor, Cabrillo Beach (San Pedro), and two coves at Catalina Island.


Sources of information:

2002 Red Alert! New Introductions and Recent Expansions in California. Mandy Tu and John M. Randall. The Nature Conservancy's Wildland Invasive Species Team.
John Knapp, Catalina Island Conservatory, Personal communication, April 2005


Question 2.4 Innate reproductive potential? B Reviewed Scientific Publication
Describe key reproductive characteristics:

An annual. From July to September 2001, there was limited recruitment of new Undaria sporophytes. Experimental manipulations provided evidence of fast re-colonization potential of algae mainly attributable to its efficient reproductive system. After the laterally biflagellate, haploid spores are released, typically swim for up to 5-6 h before settling on a firm substrate, where they develop directly into microscopic, filamentous male and female gametophytes. male gametes fertilize eggs, which then develop in situ into embryonic sporophytes. A single frond releases an astronomical number of zoospores, which appear to settle randomly. Probably all fertilized eggs develop into embryonic sporophytes. If the latter manage to survive grazers, their very rapid growth ensures continued survival unless the spores settle intertidally.


Sources of information:

Thornber, C., B. Kinlan, M. Graham, and J. Stachowicz. 2002. Invasive ecology of the Japanese alga Undaria pinnatifida in California (abstract only). Cal-EPPC Symposium 2002, Vol 6, 2000-2002.
2002 Red Alert! New Introductions and Recent Expansions in California. Mandy Tu and John M. Randall. The Nature Conservancy's Wildland Invasive Species Team.
Edgar, G.J., N.S. Barrett, A.J. Morton, and C.R. Samson. 2004. Effects of algal canopy clearance on plant, fish and macroinvertebrate communities on eastern Tasmanian reefs. J Exp Mar Bio and Eco. 312: 67 - 87.
Curiel, D. P. Guidetti, B. Bellemo, M. Scattolin, and M Marzocchi. The introduced alga Undaria pinnatifida in the lagoon of Venice. Hydrobiologia. 477 1 June, 2002. 209-219.
Silva, P.C., R.A. Woodfield, A.N. Cohen, and L.H. Harris, and J.H.R. Goddard. First report of the Asian kelp ndaria pinnatifida in the northeastern Pacific Ocean. Biological Invasions 4: 333-338, 2002.


Question 2.5 Potential for human-caused dispersal? A Reviewed Scientific Publication
Identify dispersal mechanisms:

The initial European introduction of Undaria to Venice has been attributed to the spat importation of the Japanese oyster Crassostrea gigas. Maritime traffic and oysters' cultivation and transport have subsequently favoured its diffusion in the following years. Undaria has been introduced through a combination of intentional transport for cultivation, accidental transport with oysters, as fouling on vessel hulls, and possibly other means. Establishment of large populations of Undaria in CA would almost certainly lead to harvesting by Asian immigrants, either for personal or commercial use.


Sources of information:

Curiel, D. P. Guidetti, B. Bellemo, M. Scattolin, and M Marzocchi. The introduced alga Undaria pinnatifida in the lagoon of Venice. Hydrobiologia. 477 1 June, 2002. 209-219.
Silva, P.C., R.A. Woodfield, A.N. Cohen, and L.H. Harris, and J.H.R. Goddard. First report of the Asian kelp ndaria pinnatifida in the northeastern Pacific Ocean. Biological Invasions 4: 333-338, 2002.


Question 2.6 Potential for natural long-distance dispersal? A Anecdotal
Identify dispersal mechanisms:

Spores can be moved in the ocean currents for long distances.


Sources of information:

Question 2.7 Other regions invaded? C Reviewed Scientific Publication
Identify other regions:

Recently established at several locations in CA coastal waters. Native to Japan, but in recent decades it has spread to coastal areas worldwide. It is already documented as invasive off the coasts of Australia, New Zealand, South America, and Europe, where it has invaded harbors and artificial substrates. It has also been found near Ensenada, Baja California Norte, Mexico. Since its appearance in 1992 in the lagoon of Venice, Undaria has gradually expanded along the banks of canals both at Chioggia and Venice, becoming the dominant species in the local algal commmunity from February to July.


Sources of information:

Cal-EPPC Symposium 2002, Vo. 6. 2000-2002.
2002 Red Alert! New Introductions and Recent Expansions in California. Mandy Tu and John M. Randall. The Nature Conservancy's Wildland Invasive Species Team.
Curiel, D. P. Guidetti, B. Bellemo, M. Scattolin, and M Marzocchi. The introduced alga Undaria pinnatifida in the lagoon of Venice. Hydrobiologia. 477 1 June, 2002. 209-219.
Silva, P.C., R.A. Woodfield, A.N. Cohen, and L.H. Harris, and J.H.R. Goddard. First report of the Asian kelp ndaria pinnatifida in the northeastern Pacific Ocean. Biological Invasions 4: 333-338, 2002.


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B Reviewed Scientific Publication

Recently established at several locations in CA coastal waters. Discovered in Santa Barbara County in April 2001. Will grow on any available firm substrate. Prefer sites that are at least somewhat protected, though they can grow in open coast sites. Growth is not prevented by organic pollution. Water temperatures along the Pacific Coast of the United states are favorable for the establishment of Undaria from at least Baja California to British Columbia. Undaria was discovered in southern California spring of 2000, and by the summer of 2001 had been collected at several CA sites from Los Angeles to Long Beach Harbors and Catalina Island as far north as Monterey Harbor. Sheltered and partially sheltered regions including the Southern California Bight, Monterey Bay, the more oceanic parts of San Francisco Bay, Tomales and Humboldt Bays would seem to offer excellent growing conditions.


Sources of information:

Cal-EPPC Symposium 2002, Vo. 6. 2000-2002.
Silva, P.C., R.A. Woodfield, A.N. Cohen, and L.H. Harris, and J.H.R. Goddard. First report of the Asian kelp ndaria pinnatifida in the northeastern Pacific Ocean. Biological Invasions 4: 333-338, 2002.


Question 3.2 Distribution/Peak frequency? D Reviewed Scientific Publication
Describe distribution:

New invader, limited distribution so far.


Sources of information:

Cal-EPPC Symposium 2002, Vo. 6. 2000-2002.
Silva, P.C., R.A. Woodfield, A.N. Cohen, and L.H. Harris, and J.H.R. Goddard. First report of the Asian kelp ndaria pinnatifida in the northeastern Pacific Ocean. Biological Invasions 4: 333-338, 2002.


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter Yes
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years No
Viable seed produced with both self-pollination and cross-pollination No
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Unknown
Fragments easily and fragments can become established elsewhere Unknown
Resprouts readily when cut, grazed, or burned Unknown
Total points: 4
Total unknowns: 3
Total score: B?

Related traits:

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systemsD, < 5%
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuariesD, < 5%
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Central West
  • Southwest