Anthropogenic Fifty people were asked to identify the

Anthropogenic impact throughout the
world has caused numerous and irrevocable changes in ecosystems. This impact is
seemingly as exponential as our own population growth has been since the 1960s–
from 3 billion in 1960, to 7.4 billion in 2016 (worldbank). Despite these
changes being obvious when looking at landscape change and at historical ecological
data, many find it difficult to recognize these changes in the long term. Especially
in marine environments, which is not a habitat we directly interact in and can
see the changes happening in. This failure to recognize changes, and assuming
the present levels of biodiversity and environmental context is what has always
been is called the “shifting baselines syndrome,” a term coined by Daniel Pauly
in 1995. Shifting baseline syndrome is a dangerous perceptual trap that may lead
to constant downgrading of environmental reference conditions in restoration or
conservation management plans.

In a paper by Papworth et al
(2008), it is proposed that this baseline shifts due to two different modes of “amnesia.”
The first, generational amnesia, occurs because younger generations are not
aware of past biological conditions, this can be attributed to age or just
experience. The second, personal amnesia, is where individuals forget their own
experience. In the first case, as there is a loss of older generations over
time, there is a loss of that information of normality. Perhaps as there is a
generational shift in the workforce, the standards of conservation are lower
due to the fact they are unaware of previous levels of biodiversity. In the
second, it can be attributed to mere forgetfulness, or perhaps by the
over-focus on only recent ecological data.

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A case study of a rural village in
Yorkshire, England interestingly illustrated both personal and generational
amnesia in a case of a shifting baseline of most common bird species in the
area (Papworth et al, 2008). Fifty people were asked to identify the three most
common bird species now and twenty years ago. This perceived data was able to
be compared to actual trends due to a great availability of historical data of bird
populations in the area.

The study found that 36% of
respondents had a static view of the abundance of species change (they named
the same three species for both periods of time). While age or interest in
birds did not seem to have a significant effect on this fact, individuals were
more likely to name species that are more abundant now than those more abundant
in the past– an example of personal amnesia. Older respondents were able to more
accurately name the three most common bird species in the past, and also
thought more species had changed than younger respondents (Figure 1).












Devastating cases of shifting
baselines can be seen throughout the fishing industry. Usually illustrated by
numbers and graphs, changes in average fish weights and species abundance are
already startling– but a paper by McClenachan (2012) gives this shift in a much
more personal touch. By looking at sport fishing “largest catch” photos from
the 1950s to the 2000s, it is apparent there is very big change in the size and
variety of fishes caught in the Florida Keys (Figure 2). This change happened
during a time when there was a “right to fish” movement by local anglers, to
protect their fishing rights. However, this increase in sports fishing with
increasing commercial fishing pressures exhausted an already strained reef
ecosystem. Because the size of the trophy boards was verifiable, the author was
able to use the photographs to measure the fish. It was found both the average
size decreased (Figure 3) and the species composition significantly changed
over time (Figure 4).



Figure 2: Photographs of fish
caught on recreational charter boats in Florida Keys from 1958, 1985, and 2007
(McClenachan, 2012).



Figure 3:  Mean size of (a) trophy fish (b)
trophy fish excluding protected species, and (c) sharks (total length) in
1956–1960, 1965–1979, 1980–1985, and 2007 (McClenachan, 2012).

Figure 4: Species composition of trophy
fish from largest to smallest. The mean size of each group within time period
is indicated with shading (McClenachan, 2012).

These examples are but two of many
cases of species abundance, frequency, or size change where the baseline of
what is normal changes over time. This has very serious implications for
conservation – if the bar is continuously lowered (or made inaccurate) for what
is ideal or normal, conservation efforts can be seriously weakened from the start.

Considering how difficult it already is to get the finances and policies in
place to make conservation happen, this is a serious matter. Shifting baselines
numb us to the reality of how much has changed in our environment and how
serious the problems are. To remedy this, historical data should be studied to
create more accurate perspectives. Another strategy is to record and encourage
the sharing of local knowledge– older generations can share their knowledge with
scientists and younger generations to help keep in mind how things are
changing. Implementing or expanding citizen science projects of seasonal or annual
monitoring of species to create a reliable record of species distributions
creates a more reliable historical record.  


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