Keeping up with the kelps

After we returned from Japan, we embarked on sampling both coasts of North America (but more on that soon!) and Europe. July, August and September blurred together, punctuated by lugging heavy bags weighed down with silica gel and bad airline food.
In the next few posts, I’ll be concluding my travel/photologues with a few highlights, in no particular order, from these trips.
France is always a good idea, so we’ll start there.



I was based for part of the French leg at the Station Biologique de Roscoff. A pretty amazing place for marine science and, personally, for my career. I conducted my dissertation research here with Myriam Valero.
I wanted to use my role here at TME to highlight the research of the different labs we visited and it was fortuitous as there is a new international lab and Franco-Chilean partnership stemming from over a decade of collaboration between labs in Roscoff and Chile. This new group called Evolutionary Biology and Ecology of Algae is detailed below.
One of the major systems studied in this group are kelps. During my PhD, Dr. Valero was leading a project called ECOKELP. They have continued this research effort in new projects detailed below. I took the opportunity to discuss with her the importance of kelp forests, an ecosystem I think is often overlooked despite its importance.
Kelps are important resources
Kelps are important primary producers in near-shore marine ecosystems. They produce a large amount of biomass, form an important part of the food web and are ecosystem engineers (i.e., habitat and shelter for a huge diversity of animals and plants; protection and stability of the coast against the destructive effect of the waves).

Major anthropogenic impacts on kelp forest communities
Multiple factors are impacting kelp forests. Coastal margins are becoming more urbanized decreasing the availability of habitats and increasing the turbidity of the water. In cold, temperate species, reproduction may cease because it is not possible for gametophytes to reproduce as temperatures increase. Moreover, dispersal is likely quite limited (less than 100 km), so fragmentation will have an effect on effective population sizes.
Population structure and demographics are important because kelps are harvested and cultivated around the world. Yet, we do not know very much about connectivity, genetic diversity or the relationship between farmed and natural populations.
Kelp harvesting – genetic impacts on natural populations
In Brittany, France, kelps are intensely harvested. In general, harvesting should cause fragmentation of populations and, therefore, reduce effective population size. However, only the largest populations are currently harvested in this part of France.
For Laminaria digitata, harvesting practices are controlled and seasonal restrictions are in place, managing the quantity of harvested material. Different sites are harvested at different times, plus the tools used to collect the seaweed (the scoubidou) does not damage the substrata.

However, the harvest of L. hyperborea is increasing and the method uses a tool that directly translates as a Norwegian comb. Though this tool will not impact soft-bottomed communities, it is detrimental to rocky subtidal zone as it destroys all the species living there.

There is also an important difference between these two kelp species. L. hyperborea has a longer life span than L. digitata. Thus, with this more damaging type of harvest, it will take longer for the long-lived species, L. hyperborea, to recover.
Harvesting can also favor opportunistic species with shorter life spans such as Saccorhiza polyschides.

It may also favor the extension of introduced kelp species through the opening up of space and decreases in genetic diversity.

Is cultivation a good alternative to over-exploitation?
In order to understand whether cultivation can be an alternative to intense harvesting, the UMI is looking at the importance of local adaptation and the scale at which populations are genetically differentiated.
One aspect they are working on is to develop cultivation of the local strains and to avoid large stands of monocultures (i.e., one genotype). In Gracilaria chilensis (see this post), cultivation of clonal strains has resulted in a huge decrease of genetic diversity. Epiphytes are destroying yields in farms. This begs the question of how resilient is this species? But, caution is necessary in order to avoid the errors in some forms of agri- and aquaculture.
IDEALG – seaweeds for the future
IDEALG is a French project called Investissement d’Avenir. It was financed in 2011 for 10 years with 12 research institutes, a technical center and five private companies specialized on aquaculture and seaweed exploitation with aims to develop the seaweed sector in France.
There are several workpackages focused on fundamental and applied research. In order to domesticate several algal species, one workpackage is exploring the reproductive biology and genetic resources (led by Dr. Valero). One of the other workpackages, led by Catherine Leblanc, investigates the complex interactions between algae and their microorganisms. Both of these lines of research are critical to the understanding of reproductive modes (is sexual or asexual reproduction dominant?) and pathogens (what microorganisms could decimate farms?).
 
UMI 3614 EBEA “Evolutionary Biology and Ecology of Algae”

This international unit was created on the 1st January 2014, comprising about 20 people from three groups in France and Chile, located in Station Biologique de Roscoff (SBR, France), Pontificia Universidad Catolica de Chile (PUCCh) in Santiago and Universidad Austral de Chile (UACh) in Valdivia. Members have been working together since 1997. From 2004 to 2012, there were more than 60 trips of personnel between Roscoff and Chile, including 6 co-directed PhD theses (I was one of those!).
The raison d’être of the UMI is to promote the collaborative links between France and Chile in basic science and education in marine science, but also on more applied issues related to algal cultivation and conservation of marine resources. This new structure is also expected to facilitate new collaborations towards European and South American scientific communities.
The group is broadly interested in evolutionary questions ranging from (i) how the wide diversity of life cycles, mating systems and life history traits observed among algae has evolved, (ii) what are the consequences of this life history diversity on adaptive processes (adaptation to global change, for example), and (iii) the evolution of reproductive isolation and speciation.
The partnership between SBR, PUCC and UACh combines different and complementary areas of expertise. Research uses a combination of theoretical (mathematical models) and experimental approaches in the field and in the laboratory on marine micro- and macroalgae which receive little attention.
Quantitatively, the UMI can be divided into these main goals:
Moving forward frontiers of Ecology and Evolution (80%): theoretical research and empirical tests of theoretical predictions are the main focus of our research that is addressing fundamental questions regarding life cycles and algal biodiversity.
Knowledge acquisition in order to develop identified applied issues (5%): basic research on life cycle and domestication processes are expected to provide useful results for the rapidly growing, and highly demanding conceptual developments in algal aquaculture.
Proposing direct responses to economic challenges, social and cultural perceptions (15%): the expected outcome of the UMI is to reinforce the international collaboration between France and Chile promoting scientific and cultural exchanges between these two countries and to increase public understanding of ecology and evolution of marine organisms. In addition, the project is expected to raise awareness among the public about the problems of conservation of marine biodiversity and to provide scientific background for rational algal resource management.
The evolution of reproductive systems and life cycles
Understanding the selective forces favoring sexual reproduction remains one of the greatest challenges in evolutionary biology. The team have developed mathematical models to explore how ploidy, population spatial structure and interactions among genes affect selection for sex and recombination. From the empirical side, they have explored the ecological correlates of sexual and asexual reproduction in brown macroalgae, such as kelps (Laminaria), and in protists, such as Coccolithophores or Alexandrium.
Although all eukaryotic sexual cycles consist of an alternation between haploid and diploid phases, the relative development of each phase varies widely among taxa, in algae in particular. They are also using theoretical approaches to understand the evolution and maintenance of this diversity of life cycles, coupled with experimental work like in red algae of the genus Gracilaria. This is on-going work with we continue to collaborate, such as the current project with G. vermiculophylla.
Speciation, hybridization and adaptation at range margins
The team has been working on two transition zones, one located in the South-Eastern Pacific (30°S, Central Chile) and the other in the North-Eastern Atlantic (Brittany, France), combining genetic and ecological data for several taxa and describing new cryptic species. One avenue of research explores changes in mating systems within contact zones between sister species (geographical parthenogenesis, transitions from outcrossing to self-fertilization) and their role in reproductive isolation. The main models are Lessonia spp and Mazzaella spp in Chile, and Laminaria spp and Fucus spp in France.
Domestication, management of genetic resources and environmental impact
Domestication not only modifies the expression of phenotypes of interest, but also leaves a genetic signature that affects both the genome structure and the genetic diversity of the domesticated species. Among the research lines currently in progress in the group is the domestication history of the red alga Gracilaria chilensis. Sexual function has been lost in this species due to extensive clonal propagation. How this influences the outcome of domestication is a fruitful future direction. The role of the reprodutive system in the domestication process has investigated through population genetics approaches, by studying clonal and partially clonal populations of G chilensis.
They also are investigating the effect of harvesting, cultivation and global change on kelp forests in different regions around Brittany. They will integrate their data with analyses at the European scale in order to implement Ecological Niche Models. The ENM’s will aid in the evaluation of the effects of climate change on the distribution range of species. In addition, they will serve to establish a European data base on the status of kelp forests along European coasts.
 
If you are interested in further information, please contact Dr. Valero at valero@sb-roscoff.fr or visit the UMI website here.