reproductive condition, with recruitment and high survival
of juveniles in the year following the earthquakes (own
data). Similarly, following the 1964 Alaska earthquake,
the deposit-feeding Macoma inconspicua appeared to
reproduce as usual and settlement occurred. These findings support the hypothesis that following earthquake disturbance, species with large vertical ranges can survive
better than those with a more restricted distribution.
Recolonization also proceeds faster for more mobile species than their sedentary counterparts, a feature demonstrated by Jaramillo et al. (2012), who investigated the
ecological effects of the 2010 Chilean earthquakes on sand
beaches.
Seagrass
Many estuarine habitats have seagrass beds at lower tidal
levels, and these provide valuable shelter and nursery
grounds for fish as well as habitat for mobile invertebrates
such as crustaceans. There are numerous reports of damaged seagrass habitats following earthquake disturbances,
with suggestions of quite rapid recolonization in some
locations. The sensitivity of seagrass to disturbances is
well known. Johansen (1971) found that, following earthquake activity, some plants died and the leaves of raised
individuals were shorter and narrower than those of the
plants remaining at lower tidal levels. In Canterbury,
New Zealand, where Zostera muelleri has a restricted distribution in anthropogenically affected estuaries, earthquake activity and liquefaction sediment mounds buried
up to 70 % of the seagrass habitat during the 2010–2012
earthquakes, with little or no recolonization almost 3 years
after the initial damage (own data).
Fish and birds
Because fish are mobile, it might be expected that they can
escape the disturbance effects of earthquake activity if
alternative feeding grounds and habitats are available.
This was, however, not the case for the thousands of rockfish and intertidal fish that died following the 1964 Alaska
earthquake (Hanna, 1971). In contrast, the effects of this
earthquake on salmonids was reviewed by Noerenberg
(1971) and Losey (2005), who summarized the potential
effects on chum, and pink salmon, as mortality of eggs
and young stages with destruction and siltation of
spawning grounds. By tracking the return of the salmonids
to individual rivers, it was suggested that less than 10 % of
their populations were lost due to the earthquake. For pink
salmon returning to subsided streams 3 years after the
quake, the decline was close to 8 %, while for uplifted
streams the decline was between 40 % and 98 %. Consistent with previous studies, it was concluded that earthquake uplift was more devastating to fishes than
subsidence. Chen et al. (2004) looked at fish populations
pre and post the 1999 M w 7.6–7.7 Chi-Chi earthquake
and landslide events in Taiwan, reporting considerable
annual variations. They concluded that disturbance
avoidance behaviors and natural resistance allowed the
fish to recover within a few months.
Following the 1964 Alaskan earthquake, scientists also
considered the effects on birds and marine mammals: both
were considered to be at risk because of their dependence
on shoreline-proximal “haul out” areas for resting, breeding, nesting, or feeding. For marine mammals the impacts
were uncertain, while the effects on birds may have been
reduced because of the timing of the earthquake. Losey
(2005) suggested that the most likely impacted groups
would be the waterfowl, ducks, and geese, while for herbivorous birds the main impacts would occur as a result
of the loss of seagrass habitats. For wading birds the loss
of potentially important feeding areas could have an
impact on resident and migratory species feeding prior to
flying back to their breeding areas. Studies on bar-tailed
godwits and oyster catchers in a small estuary in New
Zealand impacted by earthquakes in September 2010
and February 2011 have revealed that, despite reduced
habitat availability, their invertebrate prey capture rate
was similar pre and post earthquake, although this was
achieved by using different capture techniques (own data).
Species diversity
Under everyday circumstances, estuarine taxa are able to
cope with predictable disturbances including extremes of
temperature and salinity and declining oxygen levels.
Indeed, it is thought that such disturbances are necessary
for maintaining heterogeneity and, therefore, estuarine
biodiversity. Whether or not estuarine species diversity
is affected by earthquake activity is, thus, a feature of
this type of disturbance that is of special interest. In the
studies reviewed here, authors have reported a decline in
abundance and diversity following earthquakes but
then a gradual return to original community characteristics.
When a community is stressed, then conservative species
generally cope better than those that are opportunistic. Following the 2007 earthquake and tsunami event in Peru, the
soft bottom community changed; for example, gammarid
amphipods and polychaete worms were absent directly
after the tsunami; however, the functional groups and
diversity index remained the same. Mechanisms driving
this were changes in the sediment including the deposition
of finer sediment (Lomovasky et al., 2011). In estuaries
with small degrees of seismic uplift, diversity would be
expected to be maintained and new habitats rapidly colonized by more mobile species. This would be the case
where the sediments are free of contaminants and better
draining than the original sediments (own data).
Natural drivers that shape estuarine and other ecosystems include climate, physical/chemical properties, watershed geomorphology, and atmospheric and biological
processes (Harwell et al., 2010). In Prince William Sound,
the first three are dominant and regarded as being more
important than anthropogenic drivers, which include
development and resource harvesting. Both anthropogenic
disasters, such as large oil spills, and natural events, such
210
EARTHQUAKE DISTURBANCES
of juveniles in the year following the earthquakes (own
data). Similarly, following the 1964 Alaska earthquake,
the deposit-feeding Macoma inconspicua appeared to
reproduce as usual and settlement occurred. These findings support the hypothesis that following earthquake disturbance, species with large vertical ranges can survive
better than those with a more restricted distribution.
Recolonization also proceeds faster for more mobile species than their sedentary counterparts, a feature demonstrated by Jaramillo et al. (2012), who investigated the
ecological effects of the 2010 Chilean earthquakes on sand
beaches.
Seagrass
Many estuarine habitats have seagrass beds at lower tidal
levels, and these provide valuable shelter and nursery
grounds for fish as well as habitat for mobile invertebrates
such as crustaceans. There are numerous reports of damaged seagrass habitats following earthquake disturbances,
with suggestions of quite rapid recolonization in some
locations. The sensitivity of seagrass to disturbances is
well known. Johansen (1971) found that, following earthquake activity, some plants died and the leaves of raised
individuals were shorter and narrower than those of the
plants remaining at lower tidal levels. In Canterbury,
New Zealand, where Zostera muelleri has a restricted distribution in anthropogenically affected estuaries, earthquake activity and liquefaction sediment mounds buried
up to 70 % of the seagrass habitat during the 2010–2012
earthquakes, with little or no recolonization almost 3 years
after the initial damage (own data).
Fish and birds
Because fish are mobile, it might be expected that they can
escape the disturbance effects of earthquake activity if
alternative feeding grounds and habitats are available.
This was, however, not the case for the thousands of rockfish and intertidal fish that died following the 1964 Alaska
earthquake (Hanna, 1971). In contrast, the effects of this
earthquake on salmonids was reviewed by Noerenberg
(1971) and Losey (2005), who summarized the potential
effects on chum, and pink salmon, as mortality of eggs
and young stages with destruction and siltation of
spawning grounds. By tracking the return of the salmonids
to individual rivers, it was suggested that less than 10 % of
their populations were lost due to the earthquake. For pink
salmon returning to subsided streams 3 years after the
quake, the decline was close to 8 %, while for uplifted
streams the decline was between 40 % and 98 %. Consistent with previous studies, it was concluded that earthquake uplift was more devastating to fishes than
subsidence. Chen et al. (2004) looked at fish populations
pre and post the 1999 M w 7.6–7.7 Chi-Chi earthquake
and landslide events in Taiwan, reporting considerable
annual variations. They concluded that disturbance
avoidance behaviors and natural resistance allowed the
fish to recover within a few months.
Following the 1964 Alaskan earthquake, scientists also
considered the effects on birds and marine mammals: both
were considered to be at risk because of their dependence
on shoreline-proximal “haul out” areas for resting, breeding, nesting, or feeding. For marine mammals the impacts
were uncertain, while the effects on birds may have been
reduced because of the timing of the earthquake. Losey
(2005) suggested that the most likely impacted groups
would be the waterfowl, ducks, and geese, while for herbivorous birds the main impacts would occur as a result
of the loss of seagrass habitats. For wading birds the loss
of potentially important feeding areas could have an
impact on resident and migratory species feeding prior to
flying back to their breeding areas. Studies on bar-tailed
godwits and oyster catchers in a small estuary in New
Zealand impacted by earthquakes in September 2010
and February 2011 have revealed that, despite reduced
habitat availability, their invertebrate prey capture rate
was similar pre and post earthquake, although this was
achieved by using different capture techniques (own data).
Species diversity
Under everyday circumstances, estuarine taxa are able to
cope with predictable disturbances including extremes of
temperature and salinity and declining oxygen levels.
Indeed, it is thought that such disturbances are necessary
for maintaining heterogeneity and, therefore, estuarine
biodiversity. Whether or not estuarine species diversity
is affected by earthquake activity is, thus, a feature of
this type of disturbance that is of special interest. In the
studies reviewed here, authors have reported a decline in
abundance and diversity following earthquakes but
then a gradual return to original community characteristics.
When a community is stressed, then conservative species
generally cope better than those that are opportunistic. Following the 2007 earthquake and tsunami event in Peru, the
soft bottom community changed; for example, gammarid
amphipods and polychaete worms were absent directly
after the tsunami; however, the functional groups and
diversity index remained the same. Mechanisms driving
this were changes in the sediment including the deposition
of finer sediment (Lomovasky et al., 2011). In estuaries
with small degrees of seismic uplift, diversity would be
expected to be maintained and new habitats rapidly colonized by more mobile species. This would be the case
where the sediments are free of contaminants and better
draining than the original sediments (own data).
Natural drivers that shape estuarine and other ecosystems include climate, physical/chemical properties, watershed geomorphology, and atmospheric and biological
processes (Harwell et al., 2010). In Prince William Sound,
the first three are dominant and regarded as being more
important than anthropogenic drivers, which include
development and resource harvesting. Both anthropogenic
disasters, such as large oil spills, and natural events, such
210
EARTHQUAKE DISTURBANCES