43
P. orbicularis (Bangiophyceae). In Chile, these species promote kelp fisheries and
mariculture, but some are sensitive to environmental stressors such as heavy metals,
temperature, and desiccation (Contreras et al. 2007; Oppliger et al. 2012; FloresMolina et al. 2014; Schiel and Foster 2015). Moreover, plasticity, acclimation, and
tolerance responses may vary under different local environmental stress conditions
since these seaweed species inhabit different intertidal zones (i.e., upper, mid, or
lower) along a wide latitudinal gradient. Particularly along the Chilean coastline,
these species are most abundant in the upper to shallow sub-intertidal zones (Macaya
and Zuccarello 2010; Ramírez et al. 2008, 2014; Guillemin et al. 2016). These seaweeds facilitate algal and invertebrate recruitment, modulate local biological diversity
and community structure, and are commercially exploited by seaweed-based industries for alginate, bioethanol, and organic fertilizer production, abalone feed, and
human consumption (e.g., Almanza and Buschmann 2013; Aitken et al. 2014).
Notably, exports reached 530,000 tons in 2013. However, ecophysiological studies in
these organisms are scarce; and this lack of information impedes predicting potential
outcomes of global stress factors.
The impacts of heavy metal toxicity and ocean acidification enrichment on the
microscopic life stages of seaweeds have been largely ignored despite that algal
recruitment depends mainly on the survival of these early stages. The combined
results of heavy metals and pCO 2 might include shifts in species diversity and ecosystem composition due to reduced habitat range. Growth, development, and reproduction are among the life history traits of aquatic organisms known to be affected
by copper and cadmium toxicity, among other heavy metals. In L. spicata, concentrations higher than 20 μg L
−1
of dissolved copper interrupt spore development after
settling. This leads to failure in the formation of male and female gametophytes and,
as a consequence, results in a complete disruption of the normal life cycle (Contreras
et al. 2007). The absence of Lessonia from copper-enriched environments is due to
high sensitivity in the early life cycle stages, which limits growth and maturation of
the gametophytic (n) microscopic phase and, subsequently, prevents development
of the macroscopic sporophytic phase (2n).
Recently, the effects of pH shifts between 7.59 and 8.50 on meiospore germination and sex determination in the noncalcifying kelp M. pyrifera were determined,
with lower pH resulting in significantly reduced germination and kelp spore mortality (Gaitán-Espitia et al. 2014). Additionally, Roleda et al. (2012) evidenced that the
proportion of male to female M. pyrifera gametophytes was not significantly
affected by reduced pH, and inhibition of meiospore germination under low pH
could be counteracted by the availability of dissolved inorganic carbon.
In natural habitats, algae species often experience severe environmental and
anthropogenic stresses as a result of periodic exposure to a wide range of atmospheric
conditions. Therefore, the relative abundance, survivability, and distribution of seaweeds are determined mainly by specific tolerance levels to diverse environmental
stressors. In a scenario of ocean acidification, it is tempting to predict that seaweeds
will benefit from the increase in inorganic carbon concentration (Beardall et al. 1998).
However, CO 2 -driven effects on photosynthesis and growth depend on the degree to
which carbon is limiting, which in turn varies between habitat types and among taxa
3 Marine Metal Pollution and Effects on Seaweed Species
P. orbicularis (Bangiophyceae). In Chile, these species promote kelp fisheries and
mariculture, but some are sensitive to environmental stressors such as heavy metals,
temperature, and desiccation (Contreras et al. 2007; Oppliger et al. 2012; FloresMolina et al. 2014; Schiel and Foster 2015). Moreover, plasticity, acclimation, and
tolerance responses may vary under different local environmental stress conditions
since these seaweed species inhabit different intertidal zones (i.e., upper, mid, or
lower) along a wide latitudinal gradient. Particularly along the Chilean coastline,
these species are most abundant in the upper to shallow sub-intertidal zones (Macaya
and Zuccarello 2010; Ramírez et al. 2008, 2014; Guillemin et al. 2016). These seaweeds facilitate algal and invertebrate recruitment, modulate local biological diversity
and community structure, and are commercially exploited by seaweed-based industries for alginate, bioethanol, and organic fertilizer production, abalone feed, and
human consumption (e.g., Almanza and Buschmann 2013; Aitken et al. 2014).
Notably, exports reached 530,000 tons in 2013. However, ecophysiological studies in
these organisms are scarce; and this lack of information impedes predicting potential
outcomes of global stress factors.
The impacts of heavy metal toxicity and ocean acidification enrichment on the
microscopic life stages of seaweeds have been largely ignored despite that algal
recruitment depends mainly on the survival of these early stages. The combined
results of heavy metals and pCO 2 might include shifts in species diversity and ecosystem composition due to reduced habitat range. Growth, development, and reproduction are among the life history traits of aquatic organisms known to be affected
by copper and cadmium toxicity, among other heavy metals. In L. spicata, concentrations higher than 20 μg L
−1
of dissolved copper interrupt spore development after
settling. This leads to failure in the formation of male and female gametophytes and,
as a consequence, results in a complete disruption of the normal life cycle (Contreras
et al. 2007). The absence of Lessonia from copper-enriched environments is due to
high sensitivity in the early life cycle stages, which limits growth and maturation of
the gametophytic (n) microscopic phase and, subsequently, prevents development
of the macroscopic sporophytic phase (2n).
Recently, the effects of pH shifts between 7.59 and 8.50 on meiospore germination and sex determination in the noncalcifying kelp M. pyrifera were determined,
with lower pH resulting in significantly reduced germination and kelp spore mortality (Gaitán-Espitia et al. 2014). Additionally, Roleda et al. (2012) evidenced that the
proportion of male to female M. pyrifera gametophytes was not significantly
affected by reduced pH, and inhibition of meiospore germination under low pH
could be counteracted by the availability of dissolved inorganic carbon.
In natural habitats, algae species often experience severe environmental and
anthropogenic stresses as a result of periodic exposure to a wide range of atmospheric
conditions. Therefore, the relative abundance, survivability, and distribution of seaweeds are determined mainly by specific tolerance levels to diverse environmental
stressors. In a scenario of ocean acidification, it is tempting to predict that seaweeds
will benefit from the increase in inorganic carbon concentration (Beardall et al. 1998).
However, CO 2 -driven effects on photosynthesis and growth depend on the degree to
which carbon is limiting, which in turn varies between habitat types and among taxa
3 Marine Metal Pollution and Effects on Seaweed Species