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Mellanda Orn
May 9, 2015
ENG 363-02
MLA
A Review of the Effects of Climate Change on Species Ranges on the Southern California Coast
There have been apparent shifts on species range that were affected by climate change.
According to studies done by J.P. Barry and many other researchers, the world’s climate has
increased in temperature during the past 60 years. Some things that can effect these climate
changes are the El Niño-Southern Oscillations (ENSO) and the Pacific Decadal Oscillations
(PDO) (Barry et al. 673). Furthermore, the consequences of these fluctuating temperatures
caused by ENSO and PDO are seen in marine environments and species range in the oceans of
Southern California. For instance, sea surface temperatures had risen from 12.7°C to 19.4 °C
during the years of 1979 to 2009 (Henderson et al. 12). Consequently, animals that had adapted
to the cooler temperatures of southern California shores previously disappeared while new
animals such as limpets, chitons, and anemones started to inhabit the area. Nevertheless, this
review will illustrate the effects of recent climate changes that are seen in the shifts in species
ranges seen on the coast of Southern California.
Climate Change due to ENSO, PDO and Human Influence
Many natural causes can affect the world’s climate. For instance, El Niño-Southern
Oscillations (ENSO) occur every two to seven years and it has the ability to temporarily change
the world’s climate. (El Niño). El Niño-Southern Oscillations are natural occurrences that
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involve fluctuating ocean temperatures that mainly occur in the equatorial region of the Pacific
Ocean (State Climate Office of North Carolina). According to the State Climate Office of North
Carolina, fluctuating temperatures are caused by water moving in a continuous cycle from warm
areas to cold areas. ENSO events can have a significant momentary effect on the structure of
marine communities, and although temporary, these effects can reverberate over a decade (Barry
et al. 673). For instance, sea surface temperatures rose anomalously for two years preceding the
ENSO event in 1993 (Barry et al. 673). According to the California Current System, the years
where the strong and positive ENSO phases were active, it was found that ENSO was linked to
increased downwelling, warmer sea-surface temperatures, and deeper thermoclines in the
Southern California region (Henderson, et al. 160).
Another naturally occurring phenomenon that affects climate change includes the Pacific
Decadal Oscillation (PDO), which drives changes to the world’s climate (Henderson, et al. 164).
According to Elizabeth Henderson’s article on the effects of fluctuations in sea-surface
temperatures, PDO brings in warm waters from ocean counter currents into the Southern
California Region, which creates warm sea-surface temperatures along the coast of Southern
California. On the other hand, there is a cool, negative PDO phase that brings in cool water
pushed by a strong current into the Southern California region (Henderson, et al. 160). An
example of this can be seen in 1977 when a PDO regime caused a shift from cool temperatures to
warm (Figure 1).
According to Elizabeth Henderson, sea-surface temperatures had risen from 12.7°C to
19.4 °C during the years of 1979 to 2009. It is apparent that the sea-surface temperatures indicate
warmer climates, however, according to Henderson’s data, there were no long-term trends in seasurface temperatures. There was a linear regression in the PDO anomaly, which conveys a
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negative trend in the past 30 years (Figure 2). This indicates that temperatures were cooler than
normal during those years. The PDO regime switch likely caused this pattern in the last decade
(Henderson, et al. 160). This shows how naturally occurring events play a major role in climate
change. Overall, these temperature fluctuations caused by ENSO and PDO have been recognized
to affect marine animals and their ability to live in their natural environment.
Aside from naturally occurring events that cause changes in the climate, humans also take
part in climate change. For instance, humans primarily influence climate change through fossil
fuels, industrial, agriculture, and other land-use emissions (Doney et al. 14). This effects climate
change because these emissions can be long-term as it warms the planet’s surface on a global
scale.
How Climate Change Affects Species Range in Southern California Intertidal Communities
The response of natural communities to gradual climate change can be seen through
shifts in species’ abundance and the variation in areas for migration (Barry et al. 672). Coastal
communities are directly affected by these environmental changes—especially changes in the
surrounding climate. To illustrate, the El-Niño-Southern Oscillation (ENSO) events causes
temporary changes in the world’s climate (El Niño). The effects of these climate-changing events
are seen in shifts by species ranges. When there are periods of warm temperatures, species
ranges tend to migrate poleward; therefore, in areas where animals have adapted for cooler
conditions, the population regressed while species that are adapted to warm conditions begin to
increase (Barry et al. 672). In short, these changes in climate affect the abundance of species that
used to live in certain areas, which in turn, illustrates shifts in species ranges.
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To study these shifts in species range, 45 species of faunal invertebrates in central
California intertidal community were studied between 1931 to 1933 and 1993 to 1994 (Barry et
al. 672). Continuous reports of shoreline ocean temperatures were also recorded to help explain
these faunal shifts. Results demonstrate that there were distinct patterns of community change
depending on the geographic range categories (northern, cosmopolitan, southern). For instance,
the abundance of southern species increased when eight out of nine species in the southern
geographic range had a significant increase. The Serpulorbis squamigerus, a sessile aggregating
gastropod, was never reported by the Hopkins Marine Station (HMS) and was rare in the mid
1960s, however, it is now common to low and middle zones in the southern geographic area
(Barry et al. 673). Moreover, the limpet Fissurella volcano, the chiton Cyanoplax hartwegii, and
two kinds of southern sea anemones increased in the low to middle zones where they may have
found greater benefits living in warmer waters (Barry et al. 672). In addition, Barry and his
colleagues noted how the mean summer maximum temperatures increased by 2.2 °C from 1983
to 1993. The annual mean shoreline ocean temperatures in the study area also increased by
0.75°C during the past 60 years, which indicates warmer ocean waters that would attract species
who live in these types of conditions (Barry et al. 673-674). Looking at Figure 3, the recorded
temperatures illustrate an increase in temperature almost every year. The effects of this gradual
increase in temperatures is exemplified by the limpets, chitons, and anemones mentioned earlier
as their numbers suddenly began to increase in the southern geographic area where they were
never seen before.
Moreover, in another study by Manuel Bringué, Vera Pospelova, and David B. Field, a
similar pattern was seen where there were notable declines in many important species and
increases in others. Bringué and his colleagues studied marine populations through the California
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Cooperative Oceanic Fisheries Investigation Program in the Santa Barbara Basin and found that
there were many shifting compositions in zooplankton and other higher trophic levels (Bringué,
Pospelova, and Field 87). They attributed these shifts to ENSO and PDO events during the
warming phases. In general, this study observes dinoflagellate cysts, which are also zooplankton,
and primary productivity to the warming of the California Current System. This allowed more
information on the observed decline in zooplankton populations and higher trophic levels in the
CCS (Bringué, Pospelova, and Field 99). Since zooplankton indicates areas of primary
productivity, sea surface temperatures, and stratification, other pelagic organisms can be
observed to see how warming temperatures affect them (Bringué, Pospelova, and Field 99). In
that case, Bringué’s study reported a near absence in many species after 1976 and 1977. Because
of the warming temperatures, community structures change, causing certain species to move
away from the area, or perish in the new inhospitable environment (Figure 4).
On a global scale, oceans have been experiencing warmer temperatures. These warmer
temperatures cause many shifts in species ranges as they increase and decrease their population
in a certain area. Moreover, ENSO, PDO, and human influence are some of the few affects of
climate change. The effects of these warmer temperatures are seen as organisms such as sea
anemones, limpets, and chitons begin to appear in areas where they normally wouldn’t live only
because the recent changes in ocean waters provide a warm environment, which is desirable for
these organisms. In conclusion, a climate change causes most species ranges to shift in different
areas that are more desirable.
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Figure 1. Events Pacific Decadal Oscillations occurring from 1930 to 2010. A warm phase caused by PDO
occurred from 1925 to 1946, and again around 1977 to 1998 (red bars). In 1947 to 1976, there was a cool phase
(blue bars). However, these decadal cycles have been changing since 1998 since there was a cool period for only
about 3 years and following that, a warm period occurred for about 4 years. Figure from
(http://www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/ca-pdo.cfm)
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Figure 4.
(Figure from Bringué et al. 2014)
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References:
Barry J.P., Baxter C.H., Sagarin., Gilman S.E. “Climate Related, Long-Term Faunal Changes in
a California Rocky Intertidal Community.” Science 267 (1995): 672-675. Print.
Bringué, M., Pospelova V., Field, D.B. “High resolution sedimentary record of dinoflagellate
cysts reflects decadal variability and 20th century warming in the Santa Barbara Basin.”
Quaternary Science Reviews (2014): 86-87, 99. Print.
Doney, Scott C. et al. “Climate Change Impacts on Marine Ecosystems.” Annual Review of
Marine Science (2012): 11-14, 25-26. Print.
"El Niño Information." El Niño Information. California Department of Fish and Wildlife., 29
Mar. 2015. Web. 29 Mar. 2015. <http://www.dfg.ca.gov/marine/elnino.asp>.
Global Patterns - El Niño-Southern Oscillation (ENSO) | State Climate Office of North
Carolina." Global Patterns - El Niño-Southern Oscillation (ENSO) | State Climate Office
of North Carolina. NC State University, 3 May 2015. Web. 17 May 2015. http://www.ncclimate.ncsu.edu/climate/patterns/ENSO.html
Henderson E.E., Forney, K.A., Barlow J.P., Hildebrand J., Douglas A.B., Calambokidis
J., Sydeman W.J. (2014). Effects of fluctuations in sea-surface temperature on the
occurrence of small cetaceans off Southern California. 159-177.
"Northwest Fisheries Science Center." Pacific Decadal Oscillation (PDO) -. NOAA Fisheries, 8
Apr. 2015. Web. 8 Apr. 2015.
<http://www.nwfsc.noaa.gov/research/divisions/fe/estuarine/oeip/ca-pdo.cfm>.