Biology Reference
In-Depth Information
2.5
2
1.5
1
0.5
0
0
50
100
150
200
SRP (mM)
Fig. 4.2
Phosphate uptake rate as a function of external phosphate concentration (soluble reactive
phosphate, SRP), fitted to two different Michaelis-Menten equations. Taken from Gordillo et al.
(
2002
)
4.7 Conclusions
The coastal environments are characterized by strong and rapid changes in
abiotic factors, among which nutrients load play a key role. Evolution has
provided macroalgae with different mechanisms that allow for optimization of
resources available. Regarding nutrient acquisition, this implies not only
the enzymes for uptake and assimilation. A wide variety of combinations are
displayed by the different species. Some are storage specialists; others are more
restricted to external availability. Periods of intense nutrient uptake do not
necessarily mean faster growth, and during the course of the day, algae can
switch their photosynthetic energy investment from C to N and P acquisition.
Overall, the major output is that these different mechanisms for the different
species coexist at the same time in the same community, and this strategy
partitioning allows a more effective resource use, and an increased availability
of nutrients to the rest of the food web.
Future research is needed to quantify the benefits of the coexistence of mixed
strategies, and how are these combinations going to be affected by the modification
of other abiotic factors such as temperature and salinity, the latter being particularly
relevant for threatened ice-driven ecosystems such as the Arctic and the Antarctic.
Many ongoing studies are focusing on the modification of geographical distribution
boundaries for different ecologically relevant species, commonly being related to
changes in water temperature and currents pattern. However, the result might also
depend on the ability of a given species to deal with a new nutrient regime.
The incorporation of this approach to geographically relevant studies will add
knowledge on the mechanisms determining the distribution of species.
