Nuisance blooms: Are tropical seaweeds really all bad?

When asked to picture a tropical marine environment you will probable imagine a tropical coral reef: bright, vivid colours, an abundance of dazzling fish, lovely warm waters and most importantly coral. 

Branching coral and resident reef fish. Great Barrier Reef. Cairns. Australia

Yet tropical coral reefs are famously suffering from many threats, both human and environmental. These threats have caused mass coral deaths through the tropical seas. The coral reef cover in the Caribbean has declined from ∼50% in 1977 to ∼10% by 2001 (Gardner et al., 2003). And this phenomenon is not unique, with many other tropical reefs following similar trends.

In the face of these declines there have been shifts from coral dominated reefs to seaweed dominated reefs. In Jamaica, corals declined from more than 50% coverage in the late 1970 to less than 5% in 1994, with fleshy seaweeds coverage increasing to more than 90% at the same time (Hughes, 1994). Indeed, some tropical seaweeds have actually benefitted from coral reef declines caused by coral bleaching, hurricanes, disease and human activities including overfishing and eutrophication. This has allowed tropical seaweeds to increase in abundance, often becoming dominant in what used to be coral dominated reefs.

Bleached coral north of Townsville, March 2017

Bleached coral. Townsville. Queensland. Australia

In fact many scientists and policy makers interpret increases in seaweed as the single best indicator of reef degradation.

But do tropical seaweeds really deserve such a bad reputation?

Turf of seaweeds in the shallows, mainly Lobophora variegata

Lobeweed (Lobophora variegata). El Hierro. Canary Islands. © OCEANA

Tropical seaweeds are often demonised, being credited to the degradation of coral reefs by competition and overgrowth. However tropical seaweeds can in fact play a valuable part in tropical ecosystems as well.

Tropical seaweeds are highly diverse, encompassing many species including larger canopy forming wireweeds (Sargassum) species to smaller, understory lobeweeds (Lobophora) and fanweeds (Dictyota). Many animals rely on tropical seaweeds as food sources or shelter, amongst other things. Various tropical fish, including frogfish and seadragons, can be seen to mimic seaweed as a form of camouflage. In fact the aptly named Sargassum fish, shows incredible resemblance to its drifting seaweed home.

Histrio #1 Left side

Sargassum fish (Histrio histrio). Sargasso Sea. Atlantic Ocean.

Often seaweed reefs can be extensive in comparison to coral reefs. In Ningaloo (Western Australia) seaweed reef coverage was 46% compared to just 8% for coral reefs (Kobryn et al., 2011). Tropical seaweed reefs are especially common in coastal locations and can be considered one of the most prominent types of shallow water tropical habitats. Consequently these tropical reefs can play an important role within interconnected tropical seascapes.

But are all seaweed reefs equal?

Seaweeds have the potential to improve biodiversity, but some seaweed canopies can have far greater effects on diversity than others. Reefs dominated by weedy, low-stature seaweed; often associated with environments pressured by human activity or disturbance; lack the complexity required to support a plethora of plants and animals. On the other hand, seaweed reefs containing a mixture of canopy and understorey seaweeds and coral provide a high-complexity habitat that can support many levels of biodiversity.

EUO OCEANA Carlos Minguell 20150608_Malta 1 Inshore Buceo 2_014

Sargassum (Sargassum vulgare). Malta. (OCEANA/Photographer©LIFE BaĦAR for N2K)

Thus habitat quality; encompassing the coverage, density and canopy height; is important in influencing the range of plants and animals that a seaweed reef can support.

Fish recruits, including important fishery target species; have a much better survival in seaweed reefs with high quality canopies. Therefore more of these new fish recruits can join the adult populations in both coral and seaweed reefs. Consequently seaweed reefs with high quality canopies are much better at supporting fish populations, both within the seaweed reef and outside of it, compared to those with low quality.

Diagrammatic representation of seaweed reef canopy quality.
Figure 3(b) from Fulton et al., 2019. The image show the influence that canopy quality has on both juvenile and adult reef fish abundance. High quality canopies provide a more complex habitat for juvenile reef fish (black). This increases the survival of juvenile reef fish that can then replenish adult populations in both coral (grey) and seaweed (blue) reefs.

So tropical reefs can, in certain circumstances, be beneficial despite their bad reputation.

Unfortunately, their commonness in coastal areas and the belief that they are best indicators for reef degradation has increased the risk that seaweed reefs are erroneously concluded to be a result of detrimental human activity rather than a natural component of a healthy ecosystem.

In seaweed reefs, if there is no evidence that a shift from coral to seaweed has occurred then they should be considered natural components of the seascape.

Iridescent brown algae Dictyota sp.

Brown Fan Weed (Dictyota sp.). Bare Island. New South Wales. Australia

In fact seaweed reefs can often be found on coastlines and remote reefs with low pressure from human activity, being an important part of the interconnected mosaic of tropical patch habitats. These reefs merit protection and deserve recognition as key components of the tropical seascape.

So not all seaweed reefs are the same: some are indicators of an unhealthy coral reef system though others are natural tropical habitats. We need to acknowledge the assets that complex seaweed reefs can be and protect them.   

This post was based on the research of Fulton et al., (2019).

If you enjoyed this post you can find the article here:

Fulton, C.J., Abesamis, R.A., Berkström, C., Depczynski, M., Graham, N.A., Holmes, T.H., Kulbicki, M., Noble, M.M., Radford, B.T., Tano, S. and Tinkler, P., 2019. Form and function of tropical macroalgal reefs in the Anthropocene. Functional Ecology33(6), pp.989-999.


Sources:

Gardner, T.A., Côté, I.M., Gill, J.A., Grant, A. and Watkinson, A.R., 2003. Long-term region-wide declines in Caribbean corals. science301(5635), pp.958-960.

Hughes, T.P., 1994. Catastrophes, phase shifts, and large-scale degradation of a Caribbean coral reef. Science265(5178), pp.1547-1551.

Kobryn, H.T., Wouters, K. and Beckley, L.E., 2011. Ningaloo Collaboration Cluster: Habitats of the Ningaloo Reef and adjacent coastal areas determined through hyperspectral imagery.

Are all individuals of a species the same?

The definition of a species states that all individuals within a species will have the same main characteristics (Collins Dictionary, 2020). These Burchell’s zebras all share the same characteristic striped appearance for example.

zebras

A group of Burchell’s zebras. Maasai Mara National Reserve, Kenya

So each individual within a species must share similar characteristics. But does this mean each will respond to environmental change in the same way? Traditionally a species is assumed to be one homogenous unit, assuming that all individuals within the species have similar environmental tolerances irrespective of their origin within the species range. Accordingly all individuals should be able to exist anywhere within the species’ range.

But is it that simple? Do all individuals respond the same way or do some individuals have the ability to respond differently? And more pressingly: Will all individuals within a species be affected by climate change in the same way?

Kohlekraftwerk Lünen

Coal Powerplant; Kohlekraftwerk. Lünen, Germany

Greenhouse gas emissions caused by human activity have enhanced the greenhouse effect; resulting in additional warming of the Earth’s surface (Houghton et al., 1990). Of this extra heat, 93% has been absorbed by the ocean leading to surface water warming of 0.11°C per decade in the Indian Ocean, 0.07°C per decade in the Atlantic and 0.05°C per decade in the Pacific (Hoegh-Guldberg et al., 2014).

Increased mean temperatures are redistributing species across the globe with many cold-water species moving polewards; including brown seaweeds. In Europe the cold-water cuvie kelp is already showing range shifts toward northern regions and local extinctions in its southern range (Müller et al., 2009) and by 2200 two common rockweeds will be lost from European shores south of Bordeaux (Jueterbock et al., 2013).

Forest kelp or cuvie (Laminaria hyperborea)

Forest kelp or cuvie (Laminaria hyperborea). Shetland, UK

If all individuals of a species respond the same way to warming then those at the edge of the species’ range will be more likely to be subjected to temperatures outside of their tolerance. These edge populations will therefore be most susceptible to range shifts and local extinctions. Those individuals within the central range should have tolerance to the warming since there is a greater margin before they are exposed to intolerable temperatures. Thus the species should be maintained within the central range and lost at the edges.

But what if all individuals do not respond the same way? In that case central populations could be in just as vulnerable a state.

If individuals respond differently, than those from different locations might be able to tolerate temperature changes to different degrees. Therefore those in central populations may also be exposed to temperatures outside of their tolerance.

Consequently if all individuals do not respond to warming in the same way then the species could be vulnerable to climate change throughout its whole range.

So either all individuals are the same and the edge populations are most vulnerable or individuals can be different and then all populations could be vulnerable.

evil sargassum

Gulfweed (Sargassum), Rockweed (Fucus) and Sea lettuce (Ulva). Llangennith, Wales, United Kingdom

Well, a systematic review of literature relating to marine plants and seaweeds appears to help answer this question. A striking 90% of studies observed within species differences to temperature change, meaning that individuals do in fact respond differently to temperature (King et al., 2018). Therefore all populations could be vulnerable. We could see local extinctions from both the edge and the central range of many important seaweed species.

To add to that, many seaweeds have limited dispersal. This results in highly structured distributions with closely related individuals remaining in close proximity. These individuals of close relation will possess similar characteristics, including temperature tolerance. Accordingly most individuals within the population will respond similarly to warming.

09192014 Sardine Run (1)

Sardine run. Tonga

In a highly mobile species with high dispersal, for example many fish species, migrant fish can move polewards to track the tolerable temperature and replace previously resident fish that can no longer tolerate the temperature in their previous habitat. These migrants can also contribute vital genetic material to the populations allowing the population to adapt to warming.

But seaweeds are not mobile; they cannot migrate since they are generally permanently attached to a hard surface. Consequently migration cannot readily contribute to the population. This means that struggling resident seaweeds cannot be replaced by migrant seaweeds. No migration and limited dispersal also means that no new genetic material is added to the population, therefore hindering adaptation to warming.

Figure 1 from King et al., 2018
Diagrammatic representation of how low and high dispersing species will respond to warming at the edge and centre of their range. Ovals represent the experienced warming within the edge and central range. Under warming conditions low dispersing species, such as seaweeds, with individuals that tolerate different temperatures will not be able to disperse into future suitable habitats and will become locally extinct.

It seems then that whether a population is at the edge or in the centre of the species range warming can be disastrous for seaweeds.

But individuals having different tolerances might also help protect a species, given a human little help. If individuals tolerant to warming are relocated to population susceptible to warming we may be able to boost local temperature tolerances. This concept of ‘Assisted migration’ is not new, having already been developed in terrestrial forests (McLachlan et al., 2007; Aitken & Whit­lock 2013; Williams and Dumroese, 2013) and seagrass meadows (Katwijk et al., 2016).

There are far more inherent logistical problems relocating seaweeds compared to the far simpler reseeding of terrestrial trees and seagrasses, however there is growing indication that this may become a feasible option in the face of climate change.

EUO © OCEANA Carlos Minguell 34111

Rhizomes of seagrass (Posidonia oceanica). Pecorini a Mare, Filicudi island, Eolian islands, Italy. © OCEANA

So we can conclude that just because all individuals from a species must share similar characteristics this does not mean that they are all exactly the same. We need to stop considering species as a single homogenous unit and instead see all individuals as unique in their own small way.

This post was based off the research of King et al., (2018).

If you enjoyed this post you can find the article here:

King, N.G., McKeown, N.J., Smale, D.A. and Moore, P.J., 2018. The importance of phenotypic plasticity and local adaptation in driving intraspecific variability in thermal niches of marine macrophytes. Ecography41(9) 1469-1484.


Sources:

Aitken, S. N. and Whitlock, M. C. 2013. Assisted gene flow to facilitate local adaptation to climate change. Annual Review of Ecology, Evolution, and Systematics. 44: 367–388.

Collins Dictionary (2020) Definition of ’species’. HarperCollins Publishers. Date accessed 25/06/2020; https://www.collinsdictionary.com/dictionary/english/species

Houghton, J.T., Jenkins, G.J. and Ephraums, J.J., (1990) Climate change: the IPCC scientific assessment. Intergovernmental Panel on Climate change (IPCC), Cambridge University Press; Cambridge, United Kingdom

Hoegh-Guldberg, O., R. Cai, E.S. Poloczanska, P.G. Brewer, S. Sundby, K. Hilmi, V.J. Fabry, and S. Jung, 2014: The Ocean. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L.White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1655-1731.

Katwijk, M. M. et al. 2016. Global analysis of seagrass restoration: the importance of large-scale planting. Journal of Applied Ecology. 53: 567–578.

King, N.G., McKeown, N.J., Smale, D.A. and Moore, P.J., 2018. The importance of phenotypic plasticity and local adaptation in driving intraspecific variability in thermal niches of marine macrophytes. Ecography41(9): 1469-1484.

McLachlan, J. S. et al. 2007. A framework for debate of assisted migration in an era of climate change. Conservation Biology 21: 297–302.

Müller, R., Laepple, T., Bartsch, I. and Wiencke, C., 2009. Impact of oceanic warming on the distribution of seaweeds in polar and cold-temperate waters. Botanica Marina52(6): 617-638.

Jueterbock, A., Tyberghein, L., Verbruggen, H., Coyer, J.A., Olsen, J.L. and Hoarau, G., 2013. Climate change impact on seaweed meadow distribution in the North Atlantic rocky intertidal. Ecology and evolution3(5):1356-1373.

Williams, M. I. and Dumroese, R. K. 2013. Growing assisted migration: synthesis of a climate change adaptation strategy. – In: Haase, D. L. et al. (tech. coord.), National Proceedings: Forest and Conservation Nursery Associations – 2012. Proceedings RMRS-P-69. Fort Collins, CO, USA Dept of Agriculture, Forest Service, Rocky Mountain Research Station, 90–96.

Too hot to handle?

The ice is disappearing… Over this winter there was no walking on the sea around Helsinki, or in much of Finland for that matter.

In January the ice cover was dramatically lower than normal for the Baltic Sea. Normally the ice should extend from the northern parts of the Baltic down to the Gulf of Finland and the Gulf of Riga, however this year the ice was limited to just a small section of the Bothnian Bay.

Indeed this lack of ice is a tell-tale sign of a milder winter, both on land and in the sea.

Extent of ice coverage (jäätä) in the northern Baltic Sea under normal condition and those observed in January 2020. Number on ice indicate thickness. Source: Finnish Meteorological Institute

But was last winter an odd exception?

It appears not. The earth is experiencing a warming of the marine environment in general, but the Baltic Sea is warming far more severely than the average global ocean. The Baltic Sea temperature is now higher than that average temperature recorded between 1981-2010 (European Environmental Agency, 2019)

Decadal global and Baltic Sea averaged sea-surface temperature anomalies relative to a 1981-2010 baseline. Source: European environmental agency

However it is not solely the increase in temperature that is concerning for the marine environment. Shorter spells of prolonged warmer temperatures, called marine heatwaves, are also troubling.

Due to climate change the IPCC (2013) expects marine heatwaves to become more frequent, and those that we do experience to be far more intense. Already the marine environment has experienced a 54% increase in annual marine heatwave days (Oliver et al., 2018).

And Finland is no exception. Monitoring at the University of Helsinki’s Tvärminne Zoological Station points that last winter was just one long marine heatwave. Exceptionally warm conditions lasted an outstanding  142 days, and even included record breaking temperatures in February 2020 (@Tvärminne, 2020).

Water temperature over the winter of 2019/2020 recorded by temperature loggers in shallow areas near Tvärminne. Source: Tvärminne Zoological Station .

Are marine heatwaves really all that bad?

Prolonged high temperatures can induce heat stress in marine plants and seaweeds with disruptive consequences to the survival of these organisms.

This stress can reduce a marine plant or algae’s ability to persist within previously inhabited areas. Consequently heatwaves have the potential to cause local extinctions.

By 2200 three currently common seaweeds; bladder, serrated and knotted wrack; will have disappeared from any North-Atlantic shore south of 45 ° latitude due to marine heatwaves and the other effects of climate change (Jueterbock et al., 2013).

4 © OCEANA Juan Cuetos 70537

Serrated wrack, Urter island, Karmøy, Norway (Image source ©OCEANA)

How will marine heatwaves affect Baltic Sea ecosystems?

Recent research at GEOMAR Helmholtz Centre for Ocean Research sheds some light on this.

By using large, outdoor tanks called ‘mesocosms’, researchers tested how eelgrass and bladderwrack respond to heatwaves (Saha et al., 2019). Within these 1,500l tanks the eelgrass and bladderwrack were subjected to 9 day heatwaves.

EUO © OCEANA Carlos Minguell 20130706_Puck Bay_157

Eelgrass meadow, Puck Bay, Poland (Image source ©OCEANA)

So how did the plant and seaweed cope?

Well is seems that both eelgrass and bladderwrack are fairly resilient to heatwaves. The eelgrass did experience impaired growth, but also showed good signs for potential recovery. Bladderwrack, on the other hand, showed no impaired growth with the only significant effect being seen on the bacterial community living on the algae.

Therefore it seems that both eelgrass and bladderwrack will likely be able to endure short heatwaves similar to those of this experiment when experienced within the natural environment.

EUO © OCEANA Carlos Suárez 45888_2

Wrack, Västra Banken, Bothnian Sea, Sweden (Image source ©OCEANA)

However it is not all good news. The effects of long heatwaves will probably be fairly different. In a previous study subjecting eelgrass to a continuous 3 week heatwave far greater detrimental effects where observed (Winters et al., 2011).  

So a tolerance to short heatwaves does not necessarily equate to a tolerance to longer ones. Consequently the length of each heatwave will be critical to determining the effects on eelgrass and bladderwrack.

We will have to endure more and hotter marine heatwaves, as will the resident plants and animals of the Baltic Sea, yet at least eelgrass and bladderwrack seem somewhat prepared for the future.


Sources:

@Tvärminne, 2020. Tvärminne Zoological Station. Date accessed: 28/5/20. https://www.facebook.com/Tvarminne/posts/2426296717472671

European Environmental Agency, 2019. Decadal average sea surface temperature anomaly in different European seas. Date accessed: 29/5/20. https://www.eea.europa.eu/legal/copyright

IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp, doi:10.1017/CBO9781107415324.

Jueterbock, A., Tyberghein, L., Verbruggen, H., Coyer, J.A., Olsen, J.L. and Hoarau, G., 2013. Climate change impact on seaweed meadow distribution in the North Atlantic rocky intertidal. Ecology and evolution3(5), pp.1356-1373.

Saha, M., Barboza, F.R., Somerfield, P.J., Al‐Janabi, B., Beck, M., Brakel, J., Ito, M., Pansch, C., Nascimento‐Schulze, J.C., Jakobsson Thor, S. and Weinberger, F., 2020. Response of foundation macrophytes to near‐natural simulated marine heatwaves. Global Change Biology26(2), pp.417-430.

Winters, G., Nelle, P., Fricke, B., Rauch, G. and Reusch, T.B., 2011. Effects of a simulated heat wave on photophysiology and gene expression of high-and low-latitude populations of Zostera marina. Marine Ecology Progress Series435, pp.83-95.

Does diversity matter?

We are currently in a biodiversity crisis. The rate of extinction is 100 to 1000 times faster than the natural rate (Singh, 2012) and by the end of the 21st century we will have lost at least 50% of all species (Myers, 1993).

Earth render 5

A view from space

Undoubtedly, this species loss will have overwhelming effects on how we live. Biodiversity loss is not only an environmental issue, it also directly effects us as a society, as well as our development, economy and security. In fact the UN (2019) declared that biodiversity loss undermines progress towards 80% of the assessed targets of their Sustainable Development Goals.  

Much attention has been focused on the loss of species, such as the charismatic black rhino or the snow leopard. With more than 31,000 species threatened with extinction (IUCN, 2020) this is understandable. Species are undeniably important and we should aim to conserve them, but we should not ignore the fact that we are losing so much more than just species in this biodiversity decline.

Marwell Zoo - Snow Leopard

Snow leopard, Marwell Zoo, UK

Biodiversity manifests throughout scales, from ecosystems, communities, species, and even genes. Genetic diversity, or the variety of genes, is a vital part of biodiversity. Yet genetic diversity is frequently overlooked in international conservation policies.  

Genetic diversity can be represented between species: you are genetically different from your pet cat; or within species: both you and I share different genes. If genetic diversity declines within a species there can be devastating consequences to the stability and functioning of that species.

In the case of the Florida panther low genetic diversity led to a range of severe problems. In fact the species was slated for extinction, with only ~30 individuals remaining (Ohio State University, 2019). Luckily for the Florida panther this downward spiral was rescued by the addition of new genes into the genepool from eight Texas puma females. This increased genetic diversity has saved the Florida panther and now at least 230 roam the wilds of Florida.  

But what about species that have natural populations with sustained low genetic diversity?

Seagrasses have notoriously low genetic diversity, often forming vast meadows of a few clones. The genetic diversity within these meadows, though conventionally low, is also important. Seagrass meadows with greater numbers of genetically different individuals have far better growth after disturbance compared to meadows of a single clone (Reusch et al., 2005; Hughes & Stachowicz, 2011). So even in species with typically low genetic diversity, higher diversity can be beneficial.

This highlights that policy makers are making a big mistake overlooking genetic diversity. By taking genetic diversity into account we could vastly improve the effectiveness of our conservation measures. Hence, if we want to successfully conserve a species, especially a threatened species, the conservation of the genetic variation within the species is of the utmost importance.


Sources:

Hughes AR, Stachowicz JJ. 2011. Seagrass genotypic diversity increases disturbance response via complementarity and dominance. Journal of Ecology 99:445-453

IUCN 2020. The IUCN Red List of Threatened Species. Version 2020-1. https://www.iucnredlist.org. Downloaded 30 April 2020

Myers, N. (1993). Biodiversity and the precautionary principle. Ambio, 22, 2/3:74-79

Ohio State University. (2019, October 3). How the Texas puma saved the Florida panther: Uncovering the genetic details of a conservation success story. ScienceDaily. www.sciencedaily.com/releases/2019/10/191003111755.htm. Downloaded 29 April 2020

Reusch TBH, Ehlers A, Hämmerli A, Worm B. 2005. Ecosystem recovery after climatic extremes enhanced by genotypic diversity. Proceedings of the National Academy of Sciences of the United States of America 102:2826_2831 DOI 10.1073/pnas.0500008102

Singh, J. S. (2002). The biodiversity crisis: a multifaceted review. Current Science82(6), 638-647

United nations [UN] (2019) www.un.org/sustainabledevelopment/blog/2019/05/nature-decline-unprecedented-report/. Downloaded 30 April 2020

What happens in the deep?

Beyond the range of conventional diving and above where submersibles normally roam lies a unique habit rarely studied. Exploration of this new world leads to the discovery of a new wealth of biodiversity; upon each exhibition to the deep scientists come back with brand new species never known to science before.

But does seaweed really live 100m below the surface where light barely touches?

Divers Descending to Deep Ledge

NOAA scientific divers descending to 150ft, Pearl and Hermes Atoll, Hawaii

Well yes they do, in fact they can be even more abundant than the neighbouring corals. Carpets of reds and greens, with shoots up to 1m long, bloom throughout this range. Not only that but walls of mushroom-like brown algae and beds of fine green seaweed are amongst the other seaweeds that can be found.

So even in deep waters seaweeds are important players in the marine ecosystem.

And if you ever wondered what it entails to be a seaweed researcher then this is a great example. Here at FunkVeg we use many of the same techniques and can vouch for the completely new level of awkwardness these pesky critters create.

Any seaweed lover should check this out!

Learn more about deep sea algae here

Or watch the whole video here

What’s all the fuss about foundations?

What do kelp forests, mussel beds, seagrass meadows and coral reefs have in common? They are all given their name by the foundation species that creates them.

But what does being a foundation species entail?

Great Barrier Reef, Australia

Just as the foundations of your house provide structural stability keeping you house strong and stable, so too does a foundation species within an ecosystem. Because of this they are vitally important in structuring the community and maintaining a healthy ecosystem.

With the growing influence and uncertainty of human activity and environmental change the stability of the world’s ecosystems is questionable. It is therefore imperative that we understand what keeps ecosystems stable.

We know that foundation species are pivotal in ensuring ecosystem stability; but few have quantified it. Fortuitously nearly two decades worth of data and observations exists courtesy of the Santa Barbara Coastal Long-Term Ecological Research Project. Using this data researchers at the UC Santa Barbara’s Marine Science Institute posed the question:

‘Does a stable giant kelp forest result in a more stable understory community?´

MBNMS - Anemone in Kelp

Anemone in Kelp, Monterey Bay National Marine Sanctuary, USA

Well it turns out it does. Just as stable foundations ensure your house stays up, so too does a stable forest of kelp help in maintaining the stability of the under-story community of plants and animal.

Unfortunately in the face of climate change the stability of kelp is likely to change in the future. This could have devastating effects of all the plants and animals that rely on the kelp forest. Not only this, but this new research suggests that all habitats reliant on foundations species may also face such similar problems. Without the important species providing a foundation for all the other plants and animals, we could see devastating changes to these iconic habitats.

So the take home note:

Just as you have to take care of the foundations of your house to prevent it collapsing, so too do we have to take care of the foundations of our ecosystems or face calamitous consequences.

Scorpionfish In Seagrass

Scorpionfish in Seagrass, NOAA Florida Keys National Marine Sanctuary, USA

If you want to read more about this research check out this link or article below:

https://www.news.ucsb.edu/2020/019772/strong-foundation

Lamy, T., Koenigs, C., Holbrook, S.J., Miller, R.J., Stier, A.C. and Reed, D.C., 2020. Foundation species promote community stability by increasing diversity in a giant kelp forest. Ecology, p.e02987.

The demise of Baltic Sea wrack?

Another post about climate change, but this time closer to home. Climate change has been identified as one of the largest contributors to environmental change within the Baltic Sea. It is predicted that Baltic waters will heat by some 2–4°C and become up to 50% fresher by the end of the twenty-first century (Meier 2015).

Coastlines of the Southern Baltic Sea

Coastline of the Southern Baltic Sea

But how will Baltic wracks fair under these new conditions?

Unfortunately the future doesn’t look good for bladderwrack. Research by Antti Takolander and colleges at the University of Helsinki indicated that warming waters and increased freshness pose real threats to bladderwrack. The once abundant brown seaweed may struggle to cope with these new environmental conditions and consequently be lost from much of the Baltic Sea.

Bladder wrack peeking up above the water 4

Bladderwrack – Brofjorden, Sweden

Climate change looks bad for bladderwrack, but is that the case for all wracks of the Baltic Sea?

It seems that the future may not be as bleak for all the Baltic Sea wracks after all. Narrow wrack, having evolved within the Baltic Sea from bladderwrack, can be found nowhere else in the world. As a unique seaweed to the Baltic you might expect that the dramatically changing conditions predicted pose an even greater threat to this sister of bladderwrack. Yet a study by Luca Rugiu and colleges at the University of Turku indicates that this is in fact not the case. By subjecting narrow wrack to higher temperatures and fresher conditions replicating predicted future conditions they assumed that narrow wrack would fair as poorly as bladderwrack; however their results were surprising. Though the predicted future conditions did lead to higher mortality, those individuals that did survive were larger and grew faster.

Bladderwrack (Fucus vesiculosus) and Narrow wrack (Fucus radicans) living side by side – SW Gulf of Bothnia (northern Baltic Sea) [From Pereyra et al., 2009; CC BY 2.0]

Does this mean that narrow wrack may benefit from climate change?

In short: Yes. Those narrow wrack individuals that can withstand the predicted future conditions will benefit from the increased growth and gain a competitive advantage over those that cannot. Since where each wrack can be found is largely affected by competition between the species the future looks even worse for bladderwrack. Both wracks frequently grow side by side and if narrow wrack profit and bladderwrack lose out from future climate conditions bladderwrack may be lost from these areas and instead replaced with narrow wrack.

The future looks bleak for bladderwrack; we may end up losing vast swathes of bladderwrack forest in the Baltic. Though there is the small silver-lining that narrow wrack appears somewhat tolerant to climate change. So the future may not be all bad. We won’t see the disappearance of all the wracks from the Baltic Sea; though we will see a very different Baltic then we see today.


Sources:

Meier HEM (2015) The BACC II Author Team, Second Assessment of Climate Change for the Baltic Sea Basin, Regional Climate Studies, DOI 10.1007/978-3-319-16006-1_13

Takolander, A., Leskinen, E. and Cabeza, M., 2017. Synergistic effects of extreme temperature and low salinity on foundational macroalga Fucus vesiculosus in the northern Baltic Sea. Journal of Experimental Marine Biology and Ecology495, pp.110-118.

Rugiu, L., Manninen, I., Rothäusler, E. and Jormalainen, V., 2018. Tolerance to climate change of the clonally reproducing endemic Baltic seaweed, Fucus radicans: is phenotypic plasticity enough?. Journal of phycology54(6), pp.888-898.

The unsung hero in the fight against climate change

Buzzword of the day: Climate Change

You will have needed to be living under a rock to have not heard all about the controversial topic of climate change.

Human-induced climate change is having a dramatic effect around the world. In 2017 human-induced warming reached approximately 1°C above pre-industrial levels, with 20–40% of the global human population living in regions that have already experienced warming of more than 1.5°C above pre-industrial in at least one season (IPCC, 2018).

But why should we worry that the world is warming?

Human-induced global warming has already caused multiple observed changes in the climate including more frequent land and marine heatwaves, increases in the frequency, intensity and/or amount of heavy precipitation events, and an increased risk of droughts (IPCC 2018).

So what is causing this problem?

The answer: Greenhouse gases.

The most infamous culprit being carbon dioxide (CO2). At Mauna Loa observatory, a remote research facility located on the slope of Mauna Loa volcano [Hawaii], scientists have been recording atmospheric CO2 levels for the past 60 years and the trends are quite disturbing. Atmospheric CO2 has increased dramatically since recording first began, from 317ppm in 1960 to a high of 415 ppm in May 2019 (NOAA, 2019).

Monthly mean atmospheric carbon dioxide measured at Mauna Loa Observatory, Hawaii

Well maybe seaweed can help..

It is well publicised that trees can remove CO2 from the atmosphere by incorporating the carbon into plant material. But did you know that marine plants can help with storing CO2 from the atmosphere too? Just as with land plants, carbon can be incorporated into marine plants directly or stored in the surrounding sediment. Surprisingly marine plants can even contribute to the long-term storage of carbon in the deep ocean.

Yet it had been assumed that seaweed had little influence in storing CO2 from the atmosphere. In fact seaweed isn’t even included within the Blue Carbon initiative; a global program aiming to lessen climate change through coastal ecosystem management; whereas seagrasses, saltmarshes, and mangroves are. However a recent study published in Nature geoscience challenges this perception. Marine scientists from KAUST have confirmed the importance of seaweed in contributing to deep ocean carbon storage.

Seaweed community at Penguin Island [AU]

Unlike rooted seagrasses and mangroves, the majority of seaweed are rootless and do not remain fixed indefinitely but instead can drift on the currents and tides. This has made estimating their contribution to locking carbon away challenging. However using some cool molecular techniques this study shows that seaweed can be found regularly at depths greater than 1000m. We know that below this depth the carbon is unlikely to return to the atmosphere, and therefore can no longer contribute to the atmospheric CO2.

So it turns out seaweed could have a very important role in helping us fight climate change.

Want to know more? Check out the link below:

or find the published article:

Ortega, A., Geraldi, N.R., Alam, I. et al. Important contribution of macroalgae to oceanic carbon sequestration. Nat. Geosci. 12, 748–754 (2019) doi:10.1038/s41561-019-0421-8

https://rdcu.be/bZzWS


Sources:

IPCC, 2018: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. In Press. https://www.ipcc.ch/sr15/

NOAA (National Oceanic and Atmospheric Administration), Earth System Research Laboratory Global Monitoring Division [online], 5/12/19, Date Accessed: 23/12/19. https://www.esrl.noaa.gov/gmd/ccgg/trends/mlo.html

Sea Urchin Ranching – the new restorative fishing practice?

Vast plains of barren emptiness, devoid of life, bar one animal: the purple sea urchin. These barrens used to be some of the most productive habitats on the planet, now they are empty wastelands. 

Urchin Valley

Purple sea urchin barren – San Miguel Island, California, United States

So what happened? 

Like a story from the bible, plagues rained down on this once pleasant land. First came pestilence. The sea stars started wasting away. Next came years of extreme heat, with coastal Californian waters reaching record breaking temperatures. And finally an explosion. An explosion of purple sea urchins. Everywhere you look would be purple sea urchins. These ravenous monsters devoured the plentiful forests, one unfortunate kelp individual at a time, until nothing was left but the barren wasteland we see today. 

Sea Star Wasting Syndrome

Ochre sea star suffering sea star wasting disease – North Beach, Washington, United States

Soon there were terrible consequences for the locals as well. With the loss of kelp forests, commercial shellfisheries collapsed. Red abalones declined by 80% and many livelihoods were shattered.

All is not well on these urchin barrens either, for too much competition leads to empty stomachs. Each urchin, competing against its brothers and sisters, now finds food scarcity a real pressing problem. So many mouths to feed, nowhere near enough kelp to eat.

Purple Sea Urchin - Strongylocentrotus purpuratus

Purple sea urchins – Santa Cruz Island, California, United States

So it seems that no individual is particularly happy after this catastrophic chain of events, not the starving sea urchins, the decimated kelp, or the troubled fishermen. 

But there may be a solution, and one in which may please all involved parties, at least in part. 

The urchins are hungry, so firstly why do we not just feed them? This sounds like such an obvious idea. So let’s take the urchins from their barrens and rehome them in special ranches, where they are provided with plentiful food and allowed to grow plump. This is where the urchin’s story gets a little less happy for them. Unfortunately for them, they are considered quite the delicacy, which conversely is quite pleasing for the fishermen, who can make a good living from fattening up urchins for slaughter. Though the urchin’s eventual fate is not necessarily such a pleasant one, they have at least had a good life eating as much as they please up until the end. And the fishermen make a tasty profit. 

But best of all, the biggest beneficiary from all of this is the kelp itself. Once the ravenous urchins are removed the kelp can grow at an enormous rate, one of the fastest on the planet, and restore the wasteland to its former glory. 

So by choosing Californian sea urchins, you as a consumer can help support perhaps the only restorative fishing practice known today, one bite at a time. 

Ollie, the residential sea otter

Sea otter taking a nap in bull kelp – Race Rocks, British Columbia, Canada

Interested in finding out more? Check out the link below where you can find more info from the authors and the freely available article:

https://www.ucdavis.edu/news/california%E2%80%99s-crashing-kelp-forest/

Free-living Bladderwrack – Why should we care?

To answer this question it helps to look at the bigger picture: Why should we care about the natural environment at all? Though the reasons are many, one of the most obvious is that their functioning directly affects our society. This idea is the basis for the ecosystem services concept.

Ecosystems Services – What are they and why do we need them?

Ecosystem services are the benefits provided by the natural environment to society. They are the foundation of human well-being. These services are numerous and highly varied depending on the ecosystem. In forests and woodlands the production of wood as a raw material for the use in manufacturing is one such service. On a smaller scale, individual species can also provide important services, such as bees acting as pollinators for agricultural plants. These services are invaluable to human existence, and often come with no accompanying monetary cost. Being freely available, many are undervalued and consequently protection for the environments that provide them is frequently limited.

Though ecosystem services are often taken for granted, they are hugely important. Imagine if the continued use of pesticides, most famously neonicatoids, led to the extinction of numerous bee species. Many fruit and seed producing crops would be left unpollinated, leading to crop failure and the consequential food shortages within shops and supermarkets. Hence the ecosystem services we take for granted can have monumental effects on society and our quality of life. It therefore seems necessary to provide protections for these environments so that they can continue to provide the services we rely on.

So now we know what Ecosystem Services are – How does this relate to bladderwrack?

As an underwater environment that many people rarely, if ever, see bladderwrack forests are a hugely underrated environment in terms of their value and the ecosystem services they provide. However bladderwrack forests can be considered similar to giant kelp forests, which are some of the most productive habitats on earth.

Bladderwrack forests are highly productive environments storing large quantities of carbon. Because some of this carbon is sequestered bladderwrack can be considered to provide a service in reducing CO2 within the atmosphere and thus help our society with mitigating climate change.

This is not the only services these underwater forests provide. As an ecosystem engineer; a creature that modifies its environment; bladderwrack also provides the additional benefits of food and shelter for a myriad of different plants and animals, all of which themselves contribute to the ecosystem services provided by this habitat. Notably bladderwrack plays an important part in food production by providing nursery and feeding habitat for juvenile fish of commercial importance including cod, pike and perch. By supporting populations of these important fish species they also provide valuable recreational services including recreational fishing, boating and SCUBA diving.

Plaice resting next to an attached bladderwrack stand

An entirely different service that bladderwrack provides influences people’s health by reducing their contact with harmful environments. Within the Baltic Sea, the enrichment of water bodies with excessive nutrients has led to widespread eutrophication and resulting nuisance blooms of cyanobacteria. These blooms can be detrimental for human health and are monitored by the Finnish Environmental Institute SYKE. Importantly though, bladderwrack forests can act as filters against high nutrient inputs from terrestrial sources, providing a service in reducing excessive load of nutrients and consequently benefiting human health and well-being.

These are just a few of the ecosystem services this fascinating habitat provides, though there are numerous others that have not been listed here. We can therefore conclude that both bladderwrack and the associated community of plants and animals are important for the Baltic Sea ecosystem and many of the services we require.

What about free-living bladderwrack and the associated animal community?

Since free-living bladderwrack fulfils a similar ecological niche to the attached form, albeit generally on soft bottoms rather than rocky substrates, we surmise that it provides similar ecosystem services as well. Both forms support a similar animal community living around and on the seaweed, but the free-living form also supports an additional community living within the sediment below the algal mats. It is likely that this community will provide additional services that benefit us, however what these services are is difficult to tell unless we have a greater understanding of the associated animal communities of the free-living form. Hence this is where our study comes in. In one of our projects we are interested in identifying the animals on and below the surface of the sediment, and how these communities vary from those of bare, soft bottoms. To find out how important these creatures are to our society we will delve below the surface of this barely studied habitat.

Free-living bladderwrack forest