I. Seaweed population dynamics utilizing field and modeling studies

   II. Biomechanics as a determinant of dynamics and life history stage abundance in seaweeds

   III. Seaweed & herbivore interactions as a determinant of seaweed dynamics 

   IV. Seaweed Life History Stage Dynamics

   V. Taxonomy and distribution of seaweeds

   VI. Applied research

   VII. Publications

A. Field studies on kelps and other brown algae 

We have shown these seaweeds to have annual rings, facilitating studies of age structured dynamics (Klinger). Mortality from wounding is not age (size) dependent once the flaw (wound) exceeds the critical length. In two closely related kelp species, resource allocation to reproduction was similar in an annual and a perennial species, contrary to theoretical predictions (Klinger). Photosynthetic capacity of reproductive structures may negate any resource loss to reproductive structures. Similarly in Fucus, there was little evidence for a "cost of reproduction" (Ang).

B. Acrosiphonia, and 'Chlorochytrium' and 'Codiolum'.: 

1. Identification of 'Chlorochytrium' and 'Codiolum' as Acrosiphonia spp. life history stages using molecular techniques: Sussmann et al. 1999. 

2. Population dynamics of a host of 'Codiolum': Sussmann & DeWreede 2001. 

3. Acrosiphonia life history stage dynamics: Sussmann & DeWreede 2001. 

4. Host specificity of the Acrosiphonia sporophyte: Sussmann & DeWreede 2002 

Molecular and field studies of the macro- and micro- life history stages of a green seaweed, and the dynamics of both the microscopic endophyte stage and its hosts (other seaweeds) done by Andrea Sussmann (currently a Post-doctoral student in our laboratory). Molecular studies have shown the relationship between the unicellular endophytes ('Codiolum' and 'Chlorochytrium') and their alternative life history stages, Acrosiphonia coalita and A. arcta. The population dynamics of the endophyte and their common hosts (Mazzaella splendens and 'Petrocelis') has been explored, showing a seasonal pattern of abundance of the endophyte. A puzzling aspect of the relationship is the presence of many endophytes at the time the host plant is disintegrating. A bet-hedging strategy is proposed for this complex life history; not only are there two different phases adapted to different seasonal conditions, but there are two different hosts (a crustose and a bladed host) for the endophytic sporophyte phase.

C. Data exploration utilizing matrix models 

Pterygophora, extensive annual variation in mortality was discovered in this kelp: 

DeWreede 1984 & 1986 

Age structure data (see above) enabled the construction of a matrix model; we determined that age was not a good determinant of mortality (as had others), but that size was more so, as we had predicted based on biomechanical considerations. Survivorship was suggested to be a more important determinant of population age structure than was fecundity.

D. More general models 

Matrix models for all 3 algal life histories, application to harvesting, and a cellular automata model for exploring algal/herbivore interactions: 

Ang & DeWreede 1990, 1992; Ang et al. 1990, 1991; Grabovac, M.Sc. 1997. 

Matrix models were generated for the first time for complex algal life histories, enabling the exploration in a quantitative manner of phase dynamics.

E. Matrix modeling of Hedophyllum (a kelp) survivorship on a wave exposure gradient: 

Milligan Ph.D. Thesis 1998; Milligan & DeWreede 2000 

A matrix model showed that both water velocity and acceleration were required to predict survivorship in this kelp, and that blade shape (by tattering) promoted survival along a wave exposure gradient.

F. Probability model predicting Mazzaella (a red seaweed) survivorship along a wave exposure gradient: 

Shaughnessy et al. 1996, and a study of physical and biological factors determining the distribution of two Mazzaella species along a wave exposure gradient: 

Shaughnessy & DeWreede 2001.

G. An exploration of life history stage ratios of Mazzaella using a matrix model: 

Scrosati & DeWreede 1999

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A. Wounding and wound healing in kelps as a determinant of population structure 

1. Minimum flaw length (Pterygophora): Biedka et al. 1987 

2. Wounding (Pterygophora): DeWreede et al. 1992

B. Blade surface area and thallus integrity (in isomorphic life history stages of Mazzaella) as a determinant of survivorship along a wave exposure gradient: 

Shaughnessy et al. 1996

C. Blade tattering and holdfast integrity (Hedophyllum): 

Milligan (Ph.D. thesis 1998, and Milligan & DeWreede 2000) 

Data from these biomechanical studies were incorporated into models, with the results as indicated in Section I. Our use of matrix, cellular automata, and probability models to seaweed population dynamics have shown their utility in both testing our understanding of factors determining seaweed dynamics and, in two cases, of predicting seaweed life history stages and species distribution.

D. Attachment force in Udotea (tropical green algae): 

Collado et al. 1998 

We applied, for the first time, biomechanical studies to a sand dwelling tropical coenocytic algae, a common growth form in tropical lagoons. We determined that, contrary to temperate seaweeds attached to rocks, these algae were removed in their entirety if sufficient water generated drag occurred, but that the velocities required would occur infrequently. Blade surface area did not appear to be limited by water generated drag forces.

E. Kelp holdfasts as anchoring structures (Laminaria setchellii) and the effect of canopy cover on juvenile kelp recruitment and herbivore abundance: 

Boizard (ongoing Ph.D. studies in 2003)

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A. Age and size dependent mortality in Fucus (a brown algae): 

Ang 1991a, 1991b. 

Ang showed that mortality is size dependent in small size classes of Fucus, but independent of size in larger size classes. Nevertheless, size was shown to be a better predictor of life history events such as the onset of reproduction and mortality, than was age.

B. Limpets, littorines, and barnacles as determinants of structure in a high intertidal algal community: 

Kim & DeWreede 1996a, 1996b; Kim 1997. 

Complex interactions determined the recolonization of high intertidal seaweeds after a disturbance. These interactions were predictable based on replicated results. Interaction strength was partially a function of size and, as with Fucus above, the negative effects of a species often reversing as it and its interactors increased in size.

C. Chiton density as a determinant of Hedophyllum (a kelp) size structure: 

Markel & DeWreede 1998 

Quantification of mortality in different size classes of this kelp, as a function also of chiton (an herbivore on kelp) density, documented for these seaweeds the occurrence of size as an escape mechanism from herbivores.

D. Biomass/density relationships structure Mazzaella (a red seaweed) communities: 

Scrosati & DeWreede 1997, 1998; Scrosati 1996, 1997a, 1997b, 1998. 

For a high intertidal species of Mazzaella these studies showed the importance of frond and individual crowding in preventing desiccation and promoting photosynthesis. The self thinning relationship was shown to not occur, due to the probable clonal nature of this species.

E. Relative importance of adult canopy and herbivory as a determinant of juvenile survivorship in Hedophyllum (a kelp): 

DeWreede (in progress); Boizard (Ph.D. thesis). 

Hedophyllum canopy cover, Katharina density, and Hedophyllum juvenile recruitment has been studied for some 4 years now at sites of different but known wave exposure. More H. juveniles survive on and among clumps of articulated coralline algae than on other substrata (e.g. crustose coralline algae). This 'preference' is more pronounced under Hedophyllum canopy then when canopy is sparse. More Hedophyllum juveniles are present in the more wave exposed of our two study sites. Similarly, Katharina tunicata is more abundant in the wave exposed site than the sheltered site. Once Hedophyllum canopy is removed, Katharina density decreases significantly in both wave the wave sheltered and exposed sites, and the proportion of larger chitons decreases as a proportion of the total Katharina population.

F. Population dynamics of Codium fragile in Barkley Sound, British Columbia

The population dynamics of Codium fragile in Barkley Sound, British Columbia are being studied by Sherri Rodgers (Ph.D. in progress). Sherri is studying the seasonal abundance and growth rates of this species in relation to herbivore food preference, sand burial, and wave action.

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Seaweeds have relatively complex life histories, and we have studied both the dynamics of two genera of brown algae (Analipus and Colpomenia) and, more extensively, of species of a red seaweed genus Mazzaella; formerly Iridaea) with an isomorphic alternation of generations. For the latter we have, and are currently, investigating the mechanisms of the temporal and ecological separation of the life history stages, to test the contradictory predictions relating to the advantages of haploid over diploid life history phases, and to better understand the maintenance of isomorphy in seaweeds. 

A. Analipus life history phase distribution (field and culture studies): 

Wendy Nelson (Ph.D. research) & Nelson & De Wreede 1989

B. Colpomenia peregrina abundance and ecology:

Herbert Vandermeulen (Ph.D. research), Vandermeulen et al.1984, Vandermeulen & DeWreede 1986, Vandermeulen & DeWreede 1987

C. Life history phase distribution in Mazzaella (a red seaweed) in western North America: 

Dyck et al. 1985

D. Temporal and ecological separation of isomorphic life history stages in Mazzaella (a red seaweed): 

DeWreede & Green 1990

E. Mechanisms determining the life history phase distribution of Mazzaella (a red seaweed): 

Dyck & DeWreede 1995

F. Reliability of a chemical test to separate life history phases in the Gigartinaceae: 

Shaughnessy & DeWreede 1991 

All of the above studies have documented that the apparently isomorphic life history phases of Mazzaella species are both temporally and ecologically separated. We have shown morphological variation which manifests itself as differences in survivorship among the two (allegedly isomorphic) life history phases. This, and more subtle biomechanical differences, may serve as points for selection towards heteromorphy in these life histories. This research was aided immensely by the existence of a colorimetric test which distinguished among these isomorphic phases; we have been able to refine the test and document the seaweeds for which it is effective.

G. Mortality and cost of reproduction as determinants of life-history phase distribution of Mazzaella and its significance in the evolution of the isomorphic life history: 

Leonard Dyck, ongoing Ph.D. research. 

By utilizing a productive combination of experimental field studies, field and laboratory based biomechanical research, and a modeling approach to both test and extend our understanding of the quantitative data, we (graduate students and myself) have increased significantly our understanding of seaweed dynamics and some of the causal factors.

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A taxonomic study of the seaweeds of Northern Sulawesi, Indonesia: 

Tania Thenu, M.Sc Thesis. 

Approximately x genera and y species were identified from this little studied area of Indonesia.

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A. Testing for biologically active compounds in seaweeds from British Columbia & Korea, Antiviral compounds: 

Kim et al. 1997; Hyung-Joo Jin et al., 1997; Hudson et al. 1999(a & b) 

This research, sponsored by a grant from the Korean Government, and done in collaboration with Korean colleagues and Dr. J. Hudson from Vancouver General Hospital, has identified a number of seaweeds with compounds active against a variety of viral types. This antiviral activity can be enhanced in some cases with an appropriate application of light treatment.

B. The impact of acid mine drainage from Britannia Mines in Howe Sound, British Columbia, on Fucus populations: 

Marsden & DeWreede 2000, Marsden et al. 2003. 

This research was jointly funded by the Department of Fisheries and Oceans, and is a completed M. Sc. study by Dale Marsden. Reduced abundance of Fucus was documented within 100+ meters of the mine outfall, and healthy Fucus transplanted into the outfall area generally showed high mortality. Copper concentrations within Fucus near the outfall reached concentrations significantly higher than those of Fucus in sites not affected by the mine.

C. A review of management issues relating to macrophyte ecology: 

Chambers et al. 1999

D. A base-line study of seagrass (Zostera marina) and ghost shrimp distribution and abundance in Grice Bay, Long Beach, British Columbia: 

Sarah Carty, M. Sc. (completed in 2003). 

This was a joint research project with, and funded by, Parks Canada. Part of a larger ongoing study by Parks, Sarah documented the seasonal and spatial abundance of these two important organisms within Grice Bay. The purpose of the study was to establish base-line data to be used for future evaluation of ecosystem integrity. Information from sediment cores established the size classes, sex ratio, and density of the ghost shrimp. Other efforts using SCUBA detailed information about seagrass on size and flowering phenology; laboratory studies provided data on chlorophyll a/b ratios, and location and abundance of soluble sugars and starch within the plant, and variation over the summer months.

E. The effects of changing seaweed assemblages on invertebrate epifaunal diversity

Colin Bates, ongoing Ph. D research 

In situations of elevated anthropogenic influence, intertidal communities can exhibit shifts towards low diversity, structurally simple communities. We are examining the effects of these changes on the communities of invertebrates that use algae as habitat. Observational studies and experimental manipulations are being used to examine these relationships with regards to decreasing functional diversity using variable patterns of loss, as well as the role of functional redundancy in buffering against the effects of species loss.  

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Dyck, L.J. and R.E. DeWreede. 2006 Reproduction and survival in Mazzaella splendens (Gigartinales, Rhodophyta). Phycologia 45: (accepted November, 2005)

Salomon, A.K., J.L. Ruesink and R.E. DeWreede. 2006 Population viability, ecological processes and biodiversity: Valuing sites for reserve selection. Biological Conservation 128: 79-92.

Anderson, K., Close, L., DeWreede, R.E., Lynch, B.J., Ormond, C., and Matt Walker. 2006 Biomechanical properties and holdfast morphology of coenocytic algae (Halimedales, Chlorophyta) in Bocas del Toro, Panama. Journal of Experimental Marine Biology and Ecology 328: 155-167.

Dyck, L.J. & R.E. DeWreede 2006 Seasonal and spatial demographic patterns in the marine macroalga Mazzaella splendens (Gigartinales, Rhodophyta). Phycological Research 54: 21-31.

Sussmann, A.V., R. Scrosati, and R.E. DeWreede 2005 Seasonal synchrony of a green algal endophyte, Acrosiphonia (Codiolales), with its red algal hosts, Mastocarpus and Mazzaella (Gigartinales). Phycologia 44: 129-132.

Sussmann, A.V. and R. E. DeWreede 2005 Survival of the endophytic sporophyte of Acrosiphonia (Codiolales, Chlorophyta). J. Mar. Biol. Assoc. U.K. 85: 49-58.

Milligan, KLD & R.E. DeWreede 2004 Morphological variations do not effectively reduce drag forces at high wave exposure for the macroalgal species, Hedophyllum sessile (Laminariales, Phaeophyta). Phycologia 43: 236-244.

Marsden, D., R.E. DeWreede & C. Levings  2003  Survivorship and Growth of Fucus gardneri after Transplant to an Acid Mine Drainage-polluted Area.  Marine Pollution Bulletin 46: 65-73.

Sussmann, A. & R.E. DeWreede 2002 Host specificity of the endophytic sporophyte phase of Acrosiphonia (Codiolales, Chlorophyta) in southern British Columbia.  Phycologia 41: 169-177.

Shaughnessy, F.J. & R.E. DeWreede 2001 Size, survival and the potential for reproduction in transplants of Mazaella splendens and Mazzaella linearis (Rhodophyta).  Marine Ecology Progress Series 222: 109-118.

Sussmann, A.V.E. & R.E. DeWreede 2001 Life history of Acrosiphonia (Codiolales, Chlorophyta) in southwestern British Columbia, Canada.  American Journal of Botany 88: 1535-1544.

Milligan, K.L.D. & R.E. DeWreede  2000  Variations in holdfast attachment mechanics with developmental stage, substratum-type, season, and wave-exposure for the intertidal kelp species Hedophyllum sessile (C. Agardh) Setchell.  Journal of Experimental Marine Biology and Ecology 254: 189-209.

Sussmann, A.V. & R.E. DeWreede  2001 Seasonality of the red algal crust ‘Petrocelis franciscana’  (Gigartinales, Rhodophyta) on boulder strewn shores of southern British Columbia, Canada.  Phycological Research49: 49-59.

Marsden, A.D. & R.E. DeWreede  2000  Community structure, reproductive function and metal content of marine intertidal algae near an acid mine drainage outflow.  Environmental Pollution 110: 1-10.

DeWreede, R.E.  1999  The Gigartinales (Rhodophyta): An introduction to some current research.  Phycological Research 47: 135-138.

Scrosati, R. and R.E. DeWreede 1999 Demographic models to simulate the stable ratio between ecologically similar gametophytes and tetrasporophytes in populations of the Gigartinaceae (Rhodophyta).  Phycological Research 47: 153-158.

Chambers, P.A., DeWreede, R.E., Irlandi, E.A. & H. Vandermeulen.  1999.  Management issues in macrophyte ecology: a Canadian perspective.  Canadian Journal of Botany 77: 471-487.

Hudson, J.B., J.H. Kim, L.K. Lee, R.E. DeWreede & Y.K. Hong.  1999  Multiple antiviral activities in extracts of seaweeds from British Columbia.  Pharmaceutical Biology 37: 1-7.

Sussmann, A., B.K. Mable, R. E. DeWreede and M. Berbee.  1999  Identification of green algal endophytes as the alternate phase of Acrosiphonia (Codiolales, Chlorophyta) using ITS1 and ITS2 ribosomal DNA sequence data.  Journal of Phycology 35: 607-614.

Collado-Vides, L.R., R. DeWreede & K.L.D. Milligan.  1998  Biomechanical properties of Udotea (Halimedales, Chlorophyta) in a Mexican reef lagoon.  Phycologia 37: 443-449.

Hudson, J.B., J.H. Kim, L.K. Lee, R.E. DeWreede & Y.K. Hong.  1999  Antiviral compounds in extracts of Korean seaweeds: Evidence for multiple activities.  Journal of Applied Phycology 10: 427-434.

Markell, R. & R.E. DeWreede  1998  Mechanisms underlying the effect of the chiton Katharina tunicata (Wood) on the kelp Hedophyllum sessile (C.Agardh) Setchell: size escape and indirect effects.  Marine Ecology Progress Series 166: 151-161.

Scrosati, R. & R.E. DeWreede  1998  Effects of frond crowding on frond bleaching in the clonal intertidal alga Mazzaella cornucopiae (Rhodophyta, Gigartinaceae) from British Columbia, Canada.  Journal of Phycology 34: 228-232.

Hyung-Joo Jin, Jeong Ha Kim, Chul Hyun Sohn, R.E. DeWreede, Tae-Joo Choi, Neil Towers, Jim B. hudson, & Yong-Ki Hong.  1997  Biological activity of seaweed extracts from British Columbia, Canada and Korea: II. Inhibition of Taq DNA polymerase.  Journal of Applied Phycology 9: 383-388.

Scrosati, R. & R.E. DeWreede  1997  Dynamics of the biomass-density relationship and frond biomass inequality for Mazzaella cornucopiae (Gigartinaceae, Rhodophyta): implications for the understanding of frond interactions.  Phycologia 36: 506-516.  *Winner of the Canadian Botanical Association's J.S. Rowe Award for the Best Paper published by a student in Ecology in 1997.

Kim, J.H., Hudson, J.B., Huang, A.M., Bannister, K., Jin, H., Choi, T.J., Towers, G.H.N., Hong, Y.K., and R.E. DeWreede.  1997  Biological activities of seaweed extracts from British Columbia, Canada, and Korea: I. Antiviral Activity.  Canadian Journal of Botany 75: 1656-1660.

De Wreede, R.E.  1996  The impact of seaweed introductions on biodiversity.  Global Biodiversity 6: 2-9.

Kim, J.H. and R.E. De Wreede  1996  Distribution and feeding preference of a high intertidal littorinid.  Botanica Marina 39: 561-569.

Shaughnessy, F.J., R.E. De Wreede & E.C. Bell.  1996  Consequences of morphology and tissue strength to blade survivorship of two closely related Rhodophyta species.  Marine Ecology Progress Series 136: 257-266.

J.H. Kim and R.E. De Wreede  1996  Effects of size and season of disturbance on algal patch recovery in a rocky intertidal community.  Marine Ecology Progress Series 133: 217-228.

Dyck, L. and R.E De Wreede  1995  Patterns of seasonal demographic change in the alternate isomorphic stages of Mazzaella splendens (Gigartinales, Rhodophyta).  Phycologia 34: 390-395.

Ang, P.O., Jr. and R.E. De Wreede  1993  Simulation and analysis of the dynamics of a Fucus distichus (Phaeophyceae, Fucales) population.  Marine Ecology-Progress Series 93: 253-265.

Ang, P.O., Jr. and R.E. De Wreede  1992  Density dependence in a population of Fucus distichus.  Marine Ecology-Progress Series 90: 169-181.

De Wreede, R.E., P. Ewanchuck and F. Shaughnessy  1992  Wounding, healing, and survivorship in three kelp species.  Marine Ecology-Progress Series 82: 259-266.

Shaughnessy, F.J. and R.E. De Wreede  1991 Reliability of the resorcinol method for identifying isomorphic phases in the Gigartinaceae (Rhodophyta).  Journal of Applied Phycology 3: 121-127.

De Wreede, R.E. and L. Green  1990  Patterns of gametophyte dominance of Iridaea splendens (Rhodophyta) in Vancouver harbor, Vancouver, British Columbia.  Journal of Applied Phycology 2: 27-34.

Ang, P.O., Jr. and R.E. De Wreede  1990  Matrix models for algal life history stages.  Marine Ecology-Progress Series 59: 171-181.

Nelson, W.A. and R.E. De Wreede  1989  Reproductive phenology of Analipus japonicus (Harv.) Wynne (Phaeophyta) in the eastern North Pacific.  Jap. J. Phycol.  37: 53-56.

De Wreede, R.E. and H. Vandermeulen  1988  Lithothrix aspergillum (Rhodophyta): regrowth and interaction with Sargassum muticum (Phaeophyta) and Neorhodomela larix (Rhodophyta).  Phycologia 27: 469-476.

Klinger, T. and R.E. De Wreede  1988  Stipe rings, age, and size in populations of Laminaria setchellii Silva (Laminariales, Phaeophyta) in British Columbia, Canada.  Phycologia 27: 234-240.

Biedka, R.F., J.M. Gosline and R.E. De Wreede  1987  Biomechanical analysis of wave-induced mortality in the marine alga Pterygophora californica.  Marine Ecology-Progress Series 36: 163-170.

Vandermeulen, H. and R.E. De Wreede  1987  Analysis of a population of Colpomenia peregrina in British Columbia: relationships with environment and primary substrate.  Jap. J. Phycol. 35: 91-98.

Vandermeulen, H. and R.E. De Wreede  1986  The phenology, mortality, dispersal and canopy species interaction of Colpomenia peregrina (Sauv.) Hamel in British Columbia.  J. Exp. Mar. Biol. Ecol. 99: 31-47.

De Wreede, R.E.  1986  Demographic characteristics of Pterygophora californica (Laminariales, Phaeophyta).  Phycologia 25: 11-17.

Dyck, L., R.E. De Wreede and D. Garbary.  1985  Life history phases in Iridaea cordata (Gigartinaceae): relative abundance and distribution from British Columbia to California.  Jap. J. Phycology 33: 225-232.

De Wreede, R.E.  1984  Growth and age-class distribution of Pterygophora californica (Phaeophyta) in British Columbia, Canada.  Marine Ecology-Progress Series 19: 93-100.

Vandermeulen, H., R.E. De Wreede and K.M. Cole.  1984  Typification of three species of Colpomenia (Phaeophyta, Scytosiphonales).  Taxon 33: 324-329.

De Wreede, R.E.  1983  Sargassum muticum (Fucales, Phaeophyta) regrowth following disturbance, and interaction with Rhodomela larix (Ceramiales, Rhodophyta) in British Columbia.  Phycologia 22: 153-160.

Vandermeulen, H. and R.E. De Wreede.  1982.  The influence of orientation of an artificial substrate (transite) on settlement of marine organisms.  Ophelia 21: 41-48.

Quadir, A., P.J. Harrison and R.E. De Wreede.  1979  The effect of submergence on the photosynthesis and respiration of marine macrophytes.  Phycologia 18: 83-88.

De Wreede, R.E.  1978  Phenology of Sargassum muticum in the Strait of Georgia, British Columbia, Canada.  Syesis 11: 1-9.

De Wreede, R.E.  1978  Growth in varying culture conditions of embryos of three Hawaiian species of Sargassum (Sargassaceae, Phaeophyta).  Phycologia 17: 23-31.

Gordon, D.K. and De Wreede, R.E.  1978  Factors influencing the distribution of Egregia menziesii (Turner) Areschoug (Phaeophyta, Laminariales) in British Columbia, Canada.  Can. J. Bot.. 56: 1198-1205.

De Wreede, R.E.  1976  The phenology of three species of Sargassum (Sargassaceae, Phaeophyta) in Hawaii.  Phycologia 15: 175-183.