15
Intertidal zonation patterns along rocky coastlines depend on interactions
between several biotic and abiotic factors and the relative contribution of these at
the different tidal levels. The seminal study by Stephenson and Stephenson (1949)
established at least three intertidal zones between widely occurring tidal marks,
with each zone characterized by specific distributions and abundances of invertebrate and algal species. Posterior experimental investigations of rocky coasts around
the world have shown that the distribution and abundance of organisms in the upper
tidal zones, with longer emersion times, are usually regulated by abiotic factors such
as UV/PAR radiation, light, salinity, temperature fluctuations, nutrient availability,
and desiccation, whereas the presence and abundance of organisms in the lower tidal
zones, with longer immersion times, are mainly regulated by biological interactions
such as herbivory, predation, competition and/or facilitation (e.g., Connell 1961,
1972; Paine 1974). Additional authors have further established that these tidal
zones, or intertidal fringes, vary from shore to shore and expand or shrink depending on wave exposure, climate variables, tidal amplitude, and topographic conditions
(Mislan et al. 2009). More recently, Bird et al. (2013) also postulated that vertical
zonation patterns and shoreline water levels primarily depend not only on tide patterns but also on wave height.
Tolerant marine species are able to cope with these very stressful conditions as a
result of phenotypical plasticity (Fierro et al. 2017). As a consequence of extended
emersion periods characterized principally by water depletion, seaweeds exhibit the
intracellular production and accumulation of reactive oxygen species (ROS), as in
other environmental conditions, which can subsequently result in a condition of
oxidative stress (e.g., Rijstenbil 2001; Lee and Shin 2003; Contreras et al. 2005,
2007, 2009; Liu et al. 2007; Kumar et al. 2010, 2011).
In this chapter, we mainly focus on desiccation stress-tolerant algae species, and
particularly on two genera of the Bangiales order, Porphyra and Pyropia, which
have extraordinary capacities to withstand the harsh physical and chemical stresses
of the upper intertidal levels. These genera are ideal research models in ecophysiology, and facilitate relating high tolerances to specific abiotic stressors with local and
regional algae abundances and distributions. This chapter will also present algae
species that thrive in the lower intertidal zones and that show varying degrees of
tolerance to abiotic stressors. With this discussion, it will shed light onto some of
the physiological mechanisms accounting for the differential distribution patterns of
intertidal seaweed communities at rocky shores.
2.1.1 Early Studies Relating Desiccation Stress to Intertidal
Zonation Patterns
In intertidal zones of the northern Atlantic, species of the genus Fucus (Fucales,
Phaeophyceae) are distributed within different, but overlapping, vertical distributions (Billard et al. 2010). Indeed, Fucus species from the upper shore to the midlittoral zone show varied tolerances to desiccation (Dring and Brown 1982) and
2 Tolerance Pathways to Desiccation Stress in Seaweeds
Intertidal zonation patterns along rocky coastlines depend on interactions
between several biotic and abiotic factors and the relative contribution of these at
the different tidal levels. The seminal study by Stephenson and Stephenson (1949)
established at least three intertidal zones between widely occurring tidal marks,
with each zone characterized by specific distributions and abundances of invertebrate and algal species. Posterior experimental investigations of rocky coasts around
the world have shown that the distribution and abundance of organisms in the upper
tidal zones, with longer emersion times, are usually regulated by abiotic factors such
as UV/PAR radiation, light, salinity, temperature fluctuations, nutrient availability,
and desiccation, whereas the presence and abundance of organisms in the lower tidal
zones, with longer immersion times, are mainly regulated by biological interactions
such as herbivory, predation, competition and/or facilitation (e.g., Connell 1961,
1972; Paine 1974). Additional authors have further established that these tidal
zones, or intertidal fringes, vary from shore to shore and expand or shrink depending on wave exposure, climate variables, tidal amplitude, and topographic conditions
(Mislan et al. 2009). More recently, Bird et al. (2013) also postulated that vertical
zonation patterns and shoreline water levels primarily depend not only on tide patterns but also on wave height.
Tolerant marine species are able to cope with these very stressful conditions as a
result of phenotypical plasticity (Fierro et al. 2017). As a consequence of extended
emersion periods characterized principally by water depletion, seaweeds exhibit the
intracellular production and accumulation of reactive oxygen species (ROS), as in
other environmental conditions, which can subsequently result in a condition of
oxidative stress (e.g., Rijstenbil 2001; Lee and Shin 2003; Contreras et al. 2005,
2007, 2009; Liu et al. 2007; Kumar et al. 2010, 2011).
In this chapter, we mainly focus on desiccation stress-tolerant algae species, and
particularly on two genera of the Bangiales order, Porphyra and Pyropia, which
have extraordinary capacities to withstand the harsh physical and chemical stresses
of the upper intertidal levels. These genera are ideal research models in ecophysiology, and facilitate relating high tolerances to specific abiotic stressors with local and
regional algae abundances and distributions. This chapter will also present algae
species that thrive in the lower intertidal zones and that show varying degrees of
tolerance to abiotic stressors. With this discussion, it will shed light onto some of
the physiological mechanisms accounting for the differential distribution patterns of
intertidal seaweed communities at rocky shores.
2.1.1 Early Studies Relating Desiccation Stress to Intertidal
Zonation Patterns
In intertidal zones of the northern Atlantic, species of the genus Fucus (Fucales,
Phaeophyceae) are distributed within different, but overlapping, vertical distributions (Billard et al. 2010). Indeed, Fucus species from the upper shore to the midlittoral zone show varied tolerances to desiccation (Dring and Brown 1982) and
2 Tolerance Pathways to Desiccation Stress in Seaweeds