Changing Plankton Communities: Causes, Effects and Consequences
Laen...
Kuupäev
2019
Kättesaadav alates
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Frontiers
Abstrakt
Marine ecosystems are changing in response to multiple stressors such as global warming,
increasing carbon dioxide (CO2) and decreasing oxygen (O2) concentrations and eutrophication
of coastal waters, among others. The direct effects of these changes on plankton physiology have
been studied for decades; less are known about possible effects these changes might have on the
composition of plankton communities, and even less about what effects any such shift in plankton
community composition will have on marine ecosystems. The plankton community makes up
the base of the marine food web (i.e., primary producers, decomposers, and primary consumers)
and plays a pivotal role in global biogeochemical cycles (e.g., Falkowski and Raven, 2013). Any
change of the plankton community structure, driven by natural or human induced changes, may
consequently have indirect effects on marine ecosystem functioning.
This Research Topic focused on causes, effects and consequences of changing composition of
plankton communities. The 12 contributions to this volume include seven original research papers,
one method paper, and four reviews; all touching the state-of-the-art in current plankton research,
and each from a complementary angle.
Several of the original research papers deal with changing phytoplankton communities,
environmental drivers and ecosystem effects. Fernández-Méndez et al. analyzed sea-ice ridges and
the snow-ice interface, which are algal hotspots in the Arctic Ocean. Both sea-ice ridges and the
snow-ice interface are projected to increase due to thinning of the ice, and Fernández-Méndez
et al. described the algal communities, mostly dominated by different diatoms, in these habitats
in the Arctic. von Scheibner et al. examined the phytoplankton and bacterioplankton response
to short-term warming. Warming increased carbon availability for the bacterial community, but
the ratio between bacterial and primary production was still relatively low, suggesting it is not
much changed by short-term warming events. Cohen et al. described diatom transcriptional and
physiological responses to changes in iron availability in the open Northeast Pacific Ocean and
in the California upwelling system. They found species specific differences in gene expression to
changes in nutrient availability and taxa specific strategies for coping with Fe stress. Ajani et al.
investigated the realized niches of phytoplankton using a long-term data set collected off Eastern
Australia. They demonstrated that the ecological niches can be dynamic and that climate change
models cannot use fixed niches when forecasting the phytoplankton community composition. There are three original research papers on zooplankton
dynamics. Lips and Lips investigated the increasing importance
of the mixotrophic ciliate Mesodinium rubrum in the Baltic Sea.
The abundance of this species was higher in years of earlier
warming and the authors suggest that it plays an important
role in shaping the inorganic nutrient pools at the start of the
summer (Lips and Lips). Haraguchi et al. studied the coupling
between phytoplankton and ciliates in Danish waters over 2 years,
and demonstrated a close coupling between these communities,
suggesting top down control of the phytoplankton community
by the ciliates. Karlsson and Winder examined ecosystem effects
of two locally adapted populations of the filter feeding copepod
Eurytemora affinis that differed in size. They demonstrated that
morphologically divergent populations of the same species can
perform different ecosystem functions through differences in
quantitative and qualitative feeding, and by having different
population response to changes in resource supply and the
phytoplankton community composition.
In the method paper by Engel et al., they tested three different
ways to manipulate species loss in natural phytoplankton
communities. Dilution, filtration, and heat stress was used to
remove rare, large and sensitive species, respectively, and this can
be used as a method for non-random species manipulation in
experiments. The majority of research on species loss has used the
approach of random species removal, which may not be a suitable
approach for studies of fragile species. The method development
and standardization of approaches suggested by Engel et al. are
essential for more realistic species loss modeling.
The review papers covered different aspects of plankton
dynamics and trait-based approaches. Lindh and Pinhassi
presented a comprehensive review of bacterioplankton
communities in the Baltic Sea and environmental drivers
for community changes based on field and experimental studies.
Bartoli et al. reviewed the drivers of cyanobacterial blooms
in the Curonian Lagoon (Baltic Sea), where cyanobacteria
has benefitted from long term increase in the temperature
and reduction in the inorganic N:P ratio. A comparison of
the differences between freshwater and marine studies of
phytoplankton traits and community assembly is presented
by Weithoff and Beisner. Finally, Spilling et al. reviewed
and synthesize state-of-the-art knowledge on the observed,
long-term increase in dinoflagellate abundance in the
Baltic Sea during spring bloom and the consequences the shift from diatom to dinoflagellate dominance has for
biogeochemical cycles.
The topics of the papers published in this Research
Topic ranged from heterotrophic bacteria, phytoplankton to
zooplankton and covered different marine ecosystems. The
potential shift in community composition may have dramatic
effects on ecosystem functioning, for example on trophic transfer,
and on biogeochemical fluxes through changes in export of
organic material, i.e., the biological pump. One of the key
challenges for predicting changes to the plankton community
is to understand the various functional groups and their niche
separation in combination with individual taxa’s ability to
acclimate, adapt and compete in a changing environment. This
trait-based community ecology of plankton has started to gain
traction (Litchman and Klausmeier, 2008; Litchman et al., 2013),
and is a useful framework to investigate potential effects of
environmental change on plankton community structure. In
order to disentangle the potential consequences of shifts in
plankton communities, more empirical studies of ecological
interactions and export are needed. Hence, we consider the
research papers in this Research Topic will be a valuable
addition to the accumulating empirical evidence of how plankton
communities are modulated by natural and human induced
changes and the indirect effect this has on marine ecosystems.
This editorial is a result of funding from the Academy of Finland (decisions no 259164, KS and LT), the Estonian Research Council (no 1574P, KO) and the EU BONUS program (grant agreement 2112932-1, LT).
This editorial is a result of funding from the Academy of Finland (decisions no 259164, KS and LT), the Estonian Research Council (no 1574P, KO) and the EU BONUS program (grant agreement 2112932-1, LT).
Kirjeldus
Märksõnad
phytoplankton, ciliates, zooplankton, marine bacteria, marine ecosystems, biogeochemical cycles, global change, articles