Detalls de la publicació.


Autor(s):I. Castejón-Silvo, J. Terrados, T. Nguyen, F. Jutfelt, E. Infantes
Títol:Increased energy expenditure is an indirect effect of habitat structural complexity loss
JCR Impact Factor:6.282
Resum:1. The deterioration of coastal habitats cascades to the decline of associated fauna
by reducing trophic resource availability, shelter from predators and nursery
grounds. The decline of biogenic habitat structure, such as in kelp forests, coral
reefs, mangroves or seagrass beds, often causes a local increase in water flow
velocity and wave exposure. The impact of this change in hydrodynamics on the
energy expenditure of animals is largely unknown.
2. Here we demonstrate that loss of seagrass beds increases water current velocity,
which impacts associated pipefishes through increased energy expenditure. We
correlated ventilation frequency with metabolic rate in four pipefish species, to
be able to estimate metabolic rates in free-swimming
fish. Using a hydrodynamic
flume, we then experimentally tested the effect of current velocity and substrate
(seagrass or sand) on ventilation frequency and behaviour.
3. Ventilation frequency was consistently higher when they swam on sand substratum
compared to seagrass substratum for all species, and this was especially
noticeable for the species with prehensile tails (i.e. Nerophis ophidion). Seagrass
canopies reduced flow velocities by 7%–44%,
which increased the overall current
exposure that pipefish tolerated. N. ophidion, Syngnathus rostellatus and
Syngnathus typhle showed two behavioural responses to currents: holding on to
the seagrass canopy, and moving to areas where the current was lower (i.e. bottom)
in trials without seagrass. Most of the individuals of all species were unable
to maintain position in velocities of 15–18
cm/s on sand substratum.
4. In this work, we demonstrate the reliance on seagrass hydrodynamic shelter of
four species of pipefish. Among them, N. ophidion showed the highest seagrass
shelter dependence and vulnerability, while S. rostellatus and S. typhle are potentially
more resilient to vegetation changes. Increased energy expenditure is thus
another impact on fishes as seagrass beds and other structural habitats continue
to decline in coastal areas.

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