The Ecology and Physiology of Seaweeds: An Overview

Abstract

Seaweeds are important components of the marine ecosystem and play a vital role in coastal habitats. On the other hand, seaweeds are vulnerable to global environmental alteration and anthropogenic influences. In this chapter, we review and discuss seaweed functional groups, spatial distribution, temporal dynamic, factors affecting their diversity, distribution and abundance, and their ecological role on a coral reef. We also explain the ways in which changes in the environment affect seaweed’s physiology, growth, and reproduction. Through research in the areas of environmental variation, population, community, and ecosystem-level responses, we can build on our present conception of seaweed physiology and climate change ecology to more effectually protect and sustainably manage coastal ecosystems.KeywordsEcosystemCoastal habitatsDistribution and abundanceFunctional groupsseaweed’s physiologyCoral reef

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3© The Author(s), under exclusive license to Springer Nature Switzerland AG 2022
A. Ranga Rao, G. A. Ravishankar (eds.), Sustainable Global Resources
of Seaweeds Volume 1, https://doi.org/10.1007/978-3-030-91955-9_1
Chapter 1
The Ecology andPhysiology ofSeaweeds:
AnOverview
IslamMahmoudEl-Manaway andSarahHamdyRashedy
Abbreviations
CCA Crustose Calcareous Algae
DIN Dissolved Inorganic Nitrogen
DOC Dissolved Organic Carbon
GBR Great Barrier Reef
UV Ultraviolet Radiation
1.1 Introduction
Seaweeds are a collective term used for benthic marine macroalgae that are gener-
ally visible to the naked eye. They occupy various ecological niches, including shal-
low and deep coral reefs, deep inter-reef areas, sandy bottoms, seagrass beds,
mangroves roots, and rocky intertidal zones in all coastline areas of the world. They
can be found in almost all aquatic environments, from marine to brackish and fresh-
water, and from the tropical islands near the equator to Polar Regions. The number
of species described by taxonomists is increasing worldwide but most likely there
are several thousand species of seaweed attained from Algaebase (Guiry and Guiry
2021) which is the most accurate evaluation. Macroalgae have a signicant ecologi-
cal role in the marine ecosystem. They produce oxygen and they are a carbon diox-
ide sink (Raven etal. 2011). Moreover, many species provide protective habitats for
a wide range of ora and fauna to preserve the coastal community (Omer etal.
2021), they also provide a direct source of food for many animals (Makkar etal.
2016). Finally, macroalgae are of extreme importance in protecting coastal shores,
I. M. El-Manaway
Science Faculty, Botany Department, Suez Canal University, Ismailia, Egypt
S. H. Rashedy (*)
National Institute of Oceanography and Fisheries, NIOF, Cairo, Egypt
e-mail: sarahamdy.niof@gmail.com

4
by dissipating wave energy and capturing sediments and nutrients (Hurd et al.
2014a, b). Seaweeds respond to various climatic and physicochemical factors.
Survival, growth, and reproduction of their dependence on and vary with numerous
key environmental variables such as temperature, salinity, hydrodynamics and wave
exposure, nutrients, carbon dioxide, and pH (Harley etal. 2012). These factors form
latitudinal patterns of algal distribution (Ramos etal. 2019). The interactions of
these parameters inuence both the presence and abundance of individual taxa.
Major changes in abiotic factors take place along spatial and temporal declivity.
Large changes in temperature, light availability, and seasonality are observed; along
the coastline, steep gradients in abiotic factors exist stretching from the intertidal to
the subtidal zone; but even on very small scales, the abiotic environment of sea-
weeds may change dramatically, e.g. within algal mats (Hurd etal. 2014a, b).
1.2 Seaweed Taxonomic Groups
Seaweeds broadly comprise species included in three phyla: Rhodophyta (red
algae), Ochrophyta (brown algae, class Phaeophyceae) and Chlorophyta (green
algae, classes Bryopsidophyceae, Chlorophyceae, Dasycladophyceae,
Prasinophyceae, and Ulvophyceae). Red and brown algae are almost exclusively
marine, whilst green algae are also common in freshwater (rivers and lakes), and
even in terrestrial (rocks, walls, houses, and tree bark in damp places) situations.
The main criteria used to identify the different phyla are photosynthetic pigments,
storage food products, the cell wall components, the ne structure of the cell, and
agella (Sahoo and Seckbach 2015). Macroalgae classication has been revised in
recent years, based on DNA sequence data. Although the classication systems
have evolved over the centuries, it is generally agreed as follows:
1.2.1 Phylum Chlorophyta
It includes green species that have chlorophylls a, b with several carotenoids
(Fig.1.1). All green macroalgae are classied in a common class, called Ulvophyceae
which are a very diverse group including about 1927 species (Guiry and Guiry
2021), and distributed in all seas of the world.
1.2.2 Phylum Ochrophyta
It includes brown species that have chlorophyll a and c, and dominated by fucoxan-
thin carotenoid that gives them the brownish color (Fig.1.1). Almost all species are
seaweeds, and are of few centimeters up to 50m in length. They are utilized as food
I. M. El-Manaway and S. H. Rashedy

5
products, in cosmetics, and as fertilizers. Alginate is a component of their cell walls,
used as emulsiers, anticoagulants, and in the production of textile and rubber
(Pereira and Cotas 2020).
1.2.3 Phylum Rhodophyta
It includes species with brilliant red color due to dominance of phycoerythrin and
phycocyanin over chlorophyll a, and d, β-carotene, and a number of xanthophylls
(Fig. 1.1). Their cell walls contain colloidal components, agar, and carrageenan,
which are important for industrial and microbial products. Their extracts are known
to have antimicrobial, antiviral, and anticancer activities (Hmani etal. 2021; Lee
etal. 2021) (Fig.1.1)
Fig. 1.1 Three groups of seaweeds collected from the Red Sea by S.H.Rashedy and identied by
I.M.El-Manawy. Green algae in a, b, c. (a) Caulerpa racemosa (Forsskal) J.Agardh, (b) Halimeda
opuntia (Linnaeus) Lamouroux, (c) Codium tomentosum Stackhouse. Brown seaweed in d, e, f. (d)
Sargassum aquifolium (Turner) c. Agardh, (e) Padina boergesenii Alender & Kraft, (f) Dictyota
dichotoma (Hudson) Lamouroux. Red seaweed in g, h, i. (g) Ganonema farinosum (Lamouroux)
Fan&Yung Wang. (h) Amphiroa anceps (Lamarck) Decaisne. (i) Actinotrichia fragilis (Forsskal)
Børgesen
1 The Ecology andPhysiology ofSeaweeds: AnOverview

6
1.3 Functional Groups ofSeaweeds
Seaweeds play vital ecological roles on both the coral reefs and seashores, and their
roles have been found to be related to different morphological and structural aspects
of the thallus. Thus, a functional-form model has been used to estimate the photo-
synthetic, nutrient uptake, and structural aspects of seaweeds in relation to grazer
(Littler etal. 1983). Outer and inner seaweed structure will impact photosynthetic
efciency, ability to absorb nutrients, and resistance to predation. For example, a
thick, tough fucoid such as Fucus will be less likely to be eaten. But, due to its thick
wall, Fucus will show a lower photosynthetic and nutrient uptake efciency than
thin bladed seaweeds like Ulva (Wiencke and Bischof 2012). In tropical habitats,
macroalgae range from small, structurally simple, lamentous turfs, a few millime-
ters high, or heavily calcied crustose forms, to large leathery macrophytes, such as
Sargassum, up to several meters tall. Given this diversity, different macroalgae
should be assumed to respond in qualitatively different ways to ecological parame-
ters and the stressors associated with human activities as well as climate changes
(Ateweberhan etal. 2005). As an alternative to taxonomic groups, macroalgae can
be considered in terms of three functional groupings based on plant attributes and
ecological characteristics (El-Manawy 2008). Plant attributes are plant size, tough-
ness, photosynthetic ability, and growth. Ecological characteristics include grazing
resistance, physiological adaptation, etc. The three main classes are: (I) algal turfs,
(II) upright macroalgae (eshy and calcied), and (III) crustose calcareous algae.
Each category includes several ‘functional groups’. This approach is considered
more useful by ecologists, because it reects both physiological traits and the eco-
logical role of algae, whereas ecological roles are not well correlated with taxo-
nomic groupings (El-Manawy 2008).
1.4 Ecological Roles ofSeaweeds onCoral Reefs
Macroalgae provide vital ecological functions such as primary production construc-
tion, contribution to nitrogen xation, and cementation of reef framework, facilita-
tion of coral settlement, and creation of habitats for other reef species. The abundance
of macroalgae on the coral reefs can be recognized as a cause of coral reef degrada-
tion. Species lists in reef plant communities contain from 100 to 250 red, green, and
brown taxa. This number may double or triple on fringing coral reefs, neritic waters
have higher levels of nutrients (Dawes 1998). Brown macroalgae are only repre-
sented by a few species (˃30), some of the most common genera being Sargassum,
Padina, Dictyota, and Turbinaria (Kuffner etal. 2008). Green macroalgae are domi-
nated by calcied species, whereas red algae are primarily crustose forms. Fleshy
and turf-forming seaweeds are less abundant on coral reefs due to extensive grazing
but are known to be critical primary producers (Dubinsky and Stambler 2011).
I. M. El-Manaway and S. H. Rashedy

7
Regarding studies on seaweeds associated with coral reefs in the Red sea,
El-Manawy (2008) studied spatial variation in cover and biomass of macroalgae on
the fringing reefs of Hurghada, Egypt. Species composition and abundance signi-
cantly varied in relation to reef health. Abundant of the upright leathery assemblage
of Padina with Sargassum, Turbinaria and Hormophysa prevailed the northern
reefs (Fig.1.2).
1.4.1 Contribution toPrimary Production
A large proportion of the primary production on a coral reef is contributed by ben-
thic algae, particularly by algal turfs (Dubinsky and Stambler 2011). The primary
production of coral reef seaweeds varies according to their morphology, as noted in
the functional group. Available research from the Great Barrier Reef (GBR) indi-
cates that primary production by eshy macroalgae and crustose algae is also
important (Dean etal. 2015). The organic matter produced enters the reef food web
by several pathways. Many algae are directly consumed by herbivorous shes,
crabs, sea urchins, and mesograzers, while dissolved organic carbon released by the
algae into the water enters the microbial food web (Diaz-Pulido and Barron 2020).
Some organic matter is exported as detritus by currents and tides to adjacent habi-
tats such as seagrass meadows, mangroves, and the deeper, inter-reef seaoor.
Fig. 1.2 Seaweeds associated with coral reef in the Red Sea, Hurghada Reef, Egypt. (a) Sargassum
aquifolium. (b) Padina boergesenii. (c) Turbinaria turbinata
1 The Ecology andPhysiology ofSeaweeds: AnOverview

8
1.4.2 Nitrogen Fixation andNutrient Retention
In algal turf communities, a group of lamentous cyanobacteria are found on the
sand bottom and x signicant amounts of atmospheric nitrogen to sustain their
growth independent of dissolved nutrients (Heil etal. 2004). As dissolved inorganic
nitrogen (DIN) compounds, their levels in reef waters are very low, greater than
0.4–1.0 μML−1; ammonium-N is maximally followed by nitrate-N and then nitrite-
N.The nitrogen cycle is mostly a biological process, with all stages occurring on
coral reefs. Due to the rapid growth rates of blue-green algae and intense grazing on
turf communities, the organic nitrogen xed in algal tissue rapidly enters the food
web and becomes available for other primary producers (Diaz-Pulido and
McCook 2003).
1.4.3 Facilitation ofCoral Settlement
The settlement of invertebrates is a fundamental process simulating the structure of
marine communities and supports the ability of benthic ecosystems to recuperate
from disruption. It is well documented that specic species of crustose calcareous
algae are the preferred settlement substrate for numerous coral species. As a result,
any disturbance to the CCA-coral settlement association is a concern with recruit-
ment success. There is some proof that explains that ocean acidication (Doropoulos
et al. 2012), elevated sea temperatures (Webster et al. 2012), reduced grazing
(Birrell etal. 2008), and poor water quality (Negri and Hoogenboom 2011) change
the ecological interactions required for optimal coral settlement onto CCA.
1.4.4 Reef Degradation
Seaweeds may also cause reef degradation in ecological phase shifts, where abun-
dant reef-building corals are replaced by abundant eshy macroalgae (Diaz-Pulido
and McCook 2008). Reductions in herbivores due to overshing and increases in
nutrient inputs have been shown to cause increases in eshy macroalgal abundance,
leading to coral overgrowth by algae and, ultimately, reef degradation (El-Manawy
2008). Many adversaries, such as coral bleaching, crown-of-thorns starsh out-
breaks, extreme low tides, outbreaks of coral diseases, and storm damage (speci-
cally tropical cyclones) often lead directly to coral mortality. The dead coral
skeletons are then rapidly colonized by diverse algal communities (Halford etal.
2004). A reef community dominated by abundant, high-biomass algal turfs or larger,
eshy macroalgae may lead to overgrowth, smothering and/or shading of corals, the
exclusion of coral recruitment, and increases in pathogens, resulting in an alternate
stable state, with decreased ecological, economic and aesthetic value (Smith
etal. 2006).
I. M. El-Manaway and S. H. Rashedy

9
1.5 The Spatial andTemporal Natural Patterns ofSeaweeds
Macroalgae species exhibit populations whose distribution along coastal rocky
shores is not uniform, either in space or time. These results from complex ecologi-
cal processes, such as succession patterns, where different species have different
recruitment, growth, and mortality rates (Cervin etal. 2005). Naturally, a variety of
different patches of macroalgae species can be observed. These groups differ in a
coastline, both spatially and temporally, according to the existence or absence
(composition) of different species. For example, different seaweed species display
vertical patterns of distribution, from the uppermost to the lowermost tide levels,
giving different zones of species or zonation patterns. This is because different spe-
cies have different adaptive responses to several physicals (e.g., emersion or expo-
sure to the atmosphere), chemical (e.g., salinity), and biotic (e.g., competition,
grazing) factors, which can inuence the different locations on the shore (Hurd etal.
2014a, b).
1.6 Factors Affecting theDiversity, Distribution
andAbundance ofSeaweeds
Seaweeds respond to various climatic and physicochemical factors. Survival,
growth, and reproduction of their dependence on and vary with numerous key envi-
ronmental variables such as temperature, salinity, hydrodynamics and wave expo-
sure, nutrients, carbon dioxide, and pH (Harley etal. 2012). These factors form
latitudinal patterns of algal distribution (Ramos etal. 2019). The interactions of
these parameters impact both the occurrence and abundance of individual taxa.
1.6.1 Biotic andAbiotic Factors
The distribution and abundance of seaweeds depend on biotic and abiotic factors
that differ spatially and temporally. Biotic factors include recruitment, mortality,
dispersal, competition, and herbivory. Abiotic factors include the available resources,
such as light, carbon dioxide, mineral nutrients, substrate, and the physical param-
eters, such as wave action, aerial exposure, and temperature. All these aspects and
their interactions are of particular importance since they are all likely to be altered
in space and time (Hu and Fraser 2016).
Light (photosynthetically active radiation) and temperature are the most impor-
tant natural parameters ruling the development of macroalgal communities. Without
light, photosynthesis is not possible and temperature, as for all other organisms,
determines the performance of seaweeds at the fundamental levels of enzymatic
processes and metabolic function (Harley et al. 2012). Although seaweeds are
1 The Ecology andPhysiology ofSeaweeds: AnOverview

10
generally well adapted to their thermal environment, any deviation from the opti-
mum temperature range (daily and seasonal), particularly in situations of environ-
mental stress, contributes to variation (Chung etal. 2011). It may also have a major
effect on seaweed survival, reducing and delaying growth and leading to an increase
in mortality, which may culminate in species ‘loss. The same is true for salinity,
where a deviation from the optimum range may lead to differential development of
some species relative to others (Harley etal. 2012).
Nutrients are very important for seaweeds growth, they are usually present at low
concentrations in marine waters unaffected by anthropogenic inputs, which together
with grazing pressure (e.g., herbivorous sh), preserves the density of seaweeds at
balanced levels (Diaz-Pulido and McCook 2008). Schaffelke etal. (2005) reported
that nutrient increase enhances macroalgal growth and potentially abundance. The
Sea urchins are universal herbivores feeding on attached algae found in marine eco-
systems ranging from shallow subtidal to depths greater than 100m. They can sur-
vive primarily on detrital seaweeds produced in the shallow photic zone, capturing
these organic materials and, therefore, regulate the community structure in shallow
algal habitats (Whippo etal. 2011).
Other aspects related to hydrodynamics, such as water ow, currents, waves, and
tides, may also inuence species distributional patterns because of hydrodynami-
cally driven processes such as recruitment and detachment (Thomsen and Wernberg
2005). Thalli of intertidal macroalgae are size-limited in habitats with heavy wave
action, and regardless of their morphology, their maximum size may be limited by
water velocities that occur on exposed coasts. In small individuals, exibility allows
the plant to reorient and recongure in the ow, assuming a streamlined shape and
reducing the applied hydrodynamic force. In large individuals, exibility allows
fronds to go with the ow; a strategy that can allow the plant to minimize hydrody-
namic forces (Denny and Gaylord 2002). The combination of these different struc-
tural properties of macroalgae with the hydrodynamics and other varied natural
factors found on a shore irresponsible for differences in macroalgal communities,
giving to intertidal rocky shores the typical vertical distribution of seaweeds.
1.6.2 The Global Climate Changes
Fluctuations in global climate and its variability have an impact on biological, eco-
logical, and socioeconomic systems (Price etal. 2011). The inuences of increased
atmospheric carbon dioxide, elevated sea temperatures, increasing sea level, and
increasing UV radiation can alter the distribution, productivity, and community
composition of seaweed (Sunny 2017).
I. M. El-Manaway and S. H. Rashedy

11
1.6.2.1 Changing inOcean Temperatures
Sea surface temperature is an important physical attribute of the world’s oceans. As
the oceans absorb more heat, sea surface temperature increases, and the ocean cir-
culation patterns that transport warm and cold water around the globe change
(Huang etal. 2016). Changes in sea surface temperature can alter marine ecosys-
tems in several ways. For example, variations in ocean temperature can affect what
species of plants, animals, and microbes are present in a location, alter migration
and breeding patterns, and threaten sensitive ocean life such as corals (FAO 2018).
Temperature controls the performance of enzymatic processes and metabolic
function of seaweeds (Trincone 2017). Although macroalgae are well adapted to
their thermal environment, the environmental change could cause cellular and sub
cellular damage which could slow growth (Hoegh-Guldberg etal. 2007).
1.6.2.2 Changing inOcean Circulation
Changing in ocean circulation causes moderate shifts in species composition and
function, particularly of turfs and upright macroalgae. These changes may be sud-
den or abrupt, depending on the nature of the circulation changes (Diaz-pulido etal.
2007). Algal dispersal is dependent on ocean currents, algal distributions, and eco-
logical functions (e.g., productivity, nitrogen xation) which are sensitive to changes
in water temperature and water quality (Millar 2007). Upright algae, such as
Sargassum and Halimeda, are less homogeneous in distribution than turfs or CCA,
and hence may be more sensitive to changes in dispersal by water movements. For
example, Sargassum spp. distributions are restricted to inshore reefs and therefore
changes in ocean circulation could affect populations of these algae (Diaz-pulido
etal. 2007).
1.6.2.3 Changes inOcean Acidity
Carbon dioxide (CO2) is a critical element for photosynthesis. In terrestrial environ-
ments, an excess of CO2 may be considered as a fertilizer, exciting photosynthesis,
but in marine systems, where bicarbonate ions (HCO3−) rather than CO2 are used by
most macroalgae as a photosynthetic substrate, other problems may arise because of
excessive concentrations in seawater (Branch etal. 2013). However, the increase of
carbon dioxide concentration could drive deviations in the chemistry of seawater
carbonate and lead to a reduction in pH, the response of different marine plants to
this change will vary. They show a variety of essential functional mechanisms
affected by carbonate chemistry (e.g., dissolution and calcication rates, growth
rates, development, and survival) that allow their responses to varying so broadly.
This means it is difcult to predict how marine ecosystems will respond to ocean
acidication (Kroeker etal. 2010).
1 The Ecology andPhysiology ofSeaweeds: AnOverview

12
Although all benthic macroalgae will be exposed to changes in pH, CO2, and
calcium carbonate saturation, this will be particularly important for crustose, and
upright calcareous macroalgae and will be also potential for changes in the avail-
ability of nutrients under reduced pH (Kleypas etal. 2006). The sensitivity of all
algal groups is expected due to interactions between the effects of pH and CO2
enhancement of photosynthesis. However, calcied algae are particularly sensitive
to ocean acidication. For example, in the GBR, a decrease in pH from 8 to 7.5
reduced calcication dramatically for the alga Halimeda tuna (Sinutok etal. 2012).
Reduction of pH may also decrease calcication of Amphiroa and Corallina. CCA
is the algal group that highly sensitive to reductions of carbonate saturation state.
Minor changes in pH (from 8.1 to 7.8) reduced calcication by as much as 21 per-
cent for a coral reef community that included CCA (Cornwall etal. 2017).
1.6.2.4 Changes inLight andUltraviolet Radiation
Ultraviolet (UV) radiation is likely to continue to increase, due to the effects of
ozone depletion, and UV levels are already high in tropical regions (McKenzie etal.
2011). The most common impacts on macroalgae include direct damage to the pho-
tosynthetic apparatus (Kataria etal. 2014), DNA (Van De Poll etal. 2003), repro-
ductive tissues (Agrawal 2009), and reduction of nutrient uptake (Courtial et al.
2018). All these effects may lead to community changes, due to shifts in relative
abundance (Lotze etal. 2002). The vulnerability of algal turfs and upright macroal-
gae as a whole is moderate since there is potential for adaptation to increased UV
radiation and the impacts are likely to be restricted to shallow-water assemblages.
The vulnerability of CCA as a group is likely to be low to moderate.
1.6.2.5 Sea Level Rise
Sea level rise due to thermal expansion of the oceans and the melting of glaciers and
ice sheets is occurring at a rate of one to two millimeters per year. By 2100, the
global sea level is projected to be 310±30mm higher than in 1990 (IPCC 2019).
The direct effect of the increase in sea level is to increase the depth of water. Sea
level rise will reduce the light to seaweeds throughout their depth range and may
limit plant photosynthesis (Harley etal. 2012). Within all three algal groups, differ-
ent taxa will have very different colonization and dispersal potentials, resulting in
highly variable responses to the increase in the available substrate with sea-level
rise (Harley etal. 2006). The assumed scenario of a sea level rise is slow relative to
the life spans of most algal turfs, upright macroalgae, and CCA, and thus high rates
of colonization, growth, and reproduction will reduce the vulnerability of all mac-
roalgal groups to sea-level rise.
I. M. El-Manaway and S. H. Rashedy

13
1.7 Role ofSeaweeds inBlue Carbon Sequestration
Marine habitats are highly productive ecosystems that contribute to Blue Carbon
sequestration (Ortega etal. 2019). Fourqurean et al. 2012 pointed that, seagrass
meadows, salt marshes, and mangrove trees have complex root systems that restore
great quantities of carbon in soft sediments within their habitat. While most sea-
weeds lack root systems and grow on rocky shores where sediment accretion does
not occur and they do not accumulate carbon-rich sediments, so they have been
neglected in Blue Carbon assessments, however, calculations submitted that 25% of
exported seaweed carbon is sequestered in long-term reservoirs, such as coastal
sediments and the deep sea (Krause-Jensen etal. 2018).
Seaweeds lack lignin (complex molecules that are key structural materials in
woody plants) in their supporting structures and therefore the material within them
is more easily remineralized (the breakdown of organic material to its simplest inor-
ganic forms) than terrestrial material. However, there is a dissolved organic fraction
of carbon (DOC) which is exuded constantly from both living seaweed and from
seaweed detritus. If this carbon is transported to below the ‘carbon sequestration
horizon’ (areas of 1000m or deeper) then it is stored for periods of time signicant
enough to be considered sequestered. Some biomarker studies have found certain
compounds in seaweeds have properties that make them less labile and more refrac-
tory (resistant to being metabolized) than other components (Trevathan-Tackett
etal. 2015). For example, the sulfated polysaccharide fucoidan has been shown to
persist in sediments, and in dissolved form fucoidan is less available as a substrate
for bacteria to consume (Barrón and Duarte 2015). Carbohydrates and phenols (a
type of organic compound) have also been used as biomarkers to show the sea-
weed’s contribution to sediment carbon (Abdullah etal. 2017).
1.8 Conclusions andFuture Perspectives
Seaweeds are of ecological importance because they form structure and habitat that
provides shelter, food, and oxygen for thousands of marine organisms, such as sh,
sea urchins, and crustaceans, and protect our coasts by reducing wave action, and
storm surges. They also support commercial sheries, are used in foods, cosmetics
and medicines. Furthermore, they possess excellent survival strategies to withstand
the many environmental stresses that they are exposed to. It’s important for us to
monitor them so we can understand and manage these vital resources sustainably.
1 The Ecology andPhysiology ofSeaweeds: AnOverview

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