Study reveals trade-offs between ecosystem resistance and resilience to tropical cyclones
Findings can help managers enhance coastal recovery and restoration
efforts

Date:
March 2, 2022
Source:
Virginia Institute of Marine Science
Summary:
An international study of the impacts of 26 landfalling tropical
cyclones reveals trade-offs between ecosystem resistance and
resilience. The findings can help guide managers as they plan for
climate change and its impacts to coastal ecosystems and economies.



FULL STORY ==========================================================================
In a new study of the ecological impacts of hurricanes, an international research team addresses a question that people have asked for centuries:
when confronted by a storm, is it better to be resistant like an oak or resilient like a willow?

==========================================================================
The team's findings, reported in the March 2nd issue of Science Advances,
can help guide managers as they plan for climate change and a growing
coastal population threatened by tropical storms that are more intense
and track farther into temperate latitudes. The findings also provide a framework for guiding management decisions related to other disturbances,
such as nutrient pollution or wildfires.

The study's lead author, Dr. Christopher Patrick of William & Mary's
Virginia Institute of Marine Science, says "We found that coastal
ecosystems display consistent tradeoffs between resistance and resilience
to tropical cyclones.

Our findings emphasize that managing for increased resistance may result
in decreased resilience, and vice versa. That knowledge is key for coastal decision making, particularly as climate change alters the risk profile
with stronger, more frequent mid-latitude storms." Patrick illustrates
these management trade-offs with an example from his role as director
of the Seagrass Monitoring and Restoration Program at VIMS. "In the
Chesapeake Bay," he says, "eelgrass tends to be more stable through
time than widgeon grass, but takes longer to recover from disturbances
such as hurricanes. This trade-off, which would also apply to diebacks
from water quality or heat stress, is an important consideration for
coastal managers when choosing which species of seagrass to restore."
The research team comprises 23 scientists from 11 states, Puerto Rico, and Taiwan. Their study is linked to a research coordination network funded
by the National Science Foundation to synthesize knowledge concerning
ecosystem responses to hurricanes. Joining Patrick as co-authors and
members of the network's leadership team are Drs. John Kominoski of
Florida International University, Bill McDowell of the University of New Hampshire, and Beth Stauffer of the University of Louisiana at Lafayette.

A repeated pattern of resistance/resilience trade-offs All told, the researchers used pre- and post-storm monitoring surveys to analyze
patterns of ecosystem resistance and resilience from 26 Northern
Hemisphere storms. These made landfall between 1985 and 2018 in states
from Texas to North Carolina, as well as in Puerto Rico and Taiwan.



==========================================================================
The researchers gauged storm characteristics and impacts via total
rainfall, maximum rainfall rate, and windspeed; then grouped their
study areas into four ecosystems (freshwater, saltwater, wetland,
and terrestrial) and five "response categories," for a grand total
of 4,138 time series. The response categories documented post-storm
changes not only in the distribution and abundance of living things -- populations of mobile animals such as fishes, sedentary animals such as oysters, and vascular plants such as mangroves -- but in the ecosystem's biogeochemistry (e.g., salinity, nitrogen) and hydrography (e.g., depth
and shoreline position).

"Our study revealed a repeated pattern of trade-offs between resistance
and resilience across categories," says Patrick. The authors note these patterns are likely the outcomes of evolutionary adaptation and conform
to ecological- disturbance theories, suggesting that consistent rules
govern ecosystem susceptibility to tropical cyclones.

As one example, the researchers cite the fate of Jamaican forests
following Hurricane Gilbert. When this intense category 5 storm crossed
the island in 1988, it devastated stout, normally resistant species
such as the Jamaican treefern, allowing myrtles and other weedy, shrubby species to colonize now- open gaps in the canopy.

In another example, when Hurricane Harvey struck Texas in 2017, erosion
from this category 4 storm cut deep channels within local coastal
wetlands, favoring recovery by the taller saltmarsh cordgrass over shorter marsh species, while wetlands dominated by mangroves experienced less
erosion than marshes.

Hurricane Harvey also decreased the biomass of coastal phytoplankton
in the waters off the Texas coast, and shifted which groups were
dominant. Such changes in the community structure of microscopic
organisms -- the base of aquatic food webs -- can affect how much energy
is available for larger organisms that are ecologically and economically important in the region.



========================================================================== Knowledge to guide effective strategies The team's findings suggest
that managers seeking to enhance both resistance and resilience in
coastal ecosystems may face an impossible task. On the other hand,
their findings provide valuable guidance for choosing the single most
effective management strategy for a particular location.

"If you can't manage for both resistance and resilience," asks Patrick,
"which should you focus on? The answer depends on both specific project
goals and the expected intensity and frequency of disturbance events."
Under a relatively static, predictable climate, resistance would
generally be the better restoration strategy in areas with infrequent disturbance. "Under this scenario," says Patrick, "managers would ideally select resistance as the main feature of their restoration strategy,
so that the function you're interested in -- slowing coastal erosion, preserving water quality -- doesn't waver when it gets knocked by a big disturbance." Managers might, for instance, choose to plant mangroves
rather than marsh grasses to protect against coastal erosion, as mangroves
are more resistant to large storm waves.

However, when and where conditions are changing, resilience may emerge
as a better option. Says Patrick, "If disturbances are going to be more
severe, more frequent, or both -- outstripping the potential resistance
of a particular species -- managers might focus on resilience so that
recovery time following disturbances is quick." "If it takes 25 years
for one tree species to grow large enough to resist the average hurricane,
but hurricanes now start impacting an area every 20 years, it's probably
a waste of effort to try to cultivate it," he adds. "The best restoration strategy depends on the frequency and intensity of disturbance events
both now and in the future." Future Directions As one of the first comprehensive studies of the ecological impacts of tropical cyclones,
the team's analysis raises as many questions as it answers, and points
to several important areas for future research by the group, formally
known as the Hurricane Ecosystem Response Synthesis Network, or HERS.

Future research areas -- guided by a HERS steering committee -- include
studies of how species traits such as reproductive potential, dispersal
mode and distance, and physiological tolerance might explain patterns of resistance and resilience at the population level; or how an ecosystem's long-term or recent environmental history might influence its response
to subsequent disturbances.

For instance, scientists believe 1972's Hurricane Agnes was particularly disruptive to seagrasses in the Chesapeake Bay because it arrived in
June, before most species had gone to seed. With greater knowledge of
previous conditions, managers could better evaluate an ecosystem's likely sensitivity to a forecast disruption.

Another key area for future HERS research is determining the
stability of highly developed coastal ecosystems in the face of
tropical cyclones. Says Patrick, "Future studies will enhance our
ability to understand how local human stressors like nutrient
pollution might interact with global stressors like climate
change to influence a specific ecosystem or locality, and thus
help target efforts to enhance coastal resilience or resistance." ========================================================================== Story Source: Materials provided by
Virginia_Institute_of_Marine_Science. Original written by David
Malmquist. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Christopher J. Patrick, John S. Kominoski, William H. McDowell,
Benjamin
Branoff, David Lagomasino, Miguel Leon, Enie Hensel, Marc
J. S. Hensel, Bradley A. Strickland, T. Mitchell Aide, Anna
Armitage, Marconi Campos- Cerqueira, Victoria M. Congdon, Todd
A. Crowl, Donna J. Devlin, Sarah Douglas, Brad E. Erisman, Rusty
A. Feagin, Simon J. Geist, Nathan S.

Hall, Amber K. Hardison, Michael R. Heithaus, J. Aaron Hogan,
J. Derek Hogan, Sean Kinard, Jeremy J. Kiszka, Teng-Chiu Lin,
Kaijun Lu, Christopher J. Madden, Paul A. Montagna, Christine
S. O'Connell, C.

Edward Proffitt, Brandi Kiel Reese, Joseph W. Reustle, Kelly
L. Robinson, Scott A. Rush, Rolando O. Santos, Astrid Schnetzer,
Delbert L. Smee, Rachel S. Smith, Gregory Starr, Beth A. Stauffer,
Lily M. Walker, Carolyn A. Weaver, Michael S. Wetz, Elizabeth
R. Whitman, Sara S. Wilson, Jianhong Xue, Xiaoming Zou. A
general pattern of trade-offs between ecosystem resistance and
resilience to tropical cyclones. Science Advances, 2022; 8 (9)
DOI: 10.1126/sciadv.abl9155 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220302150355.htm

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