IMPACTS FROM DISTURBANCES,

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Kaiser part three Impacts Chapter 14
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IMPACTS FROM DISTURBANCES, POLLUTION, AND
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Kaiser part three Impacts Chapter 14
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Chapter 14 overview 1 Introduction 2
Ecological significance of disturbances
(Sources, scales, restitution rates, the IDH
hypothesis) 3 Measuring the effect of
disturbances (Univariate measures,
distribution measures, multivariate measures,
detection, experimental design, pitfalls)
4 Anthropogenic causes of disturbances
(River transport/agriculture, eutrophication,
hydropower plants, oil industry, marine mining,
chemical vaste) 5 Climate change
(Temperature effects, precipitation variation,
ocean currents/circulation, multifactor
interactions)
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Chapter 14 internal build-up The problem Human
activity all over the world is connected with a
series of changes in marine ecosystems. Many
activities concern exploitation of biological and
mineral resources, while other types of impacts
concern vaste from industry and agriculture. The
resulting changes in marine ecosystems have often
been sudden and catastrophal, other times more
subtle and not detected before after many
years. The approach To assess the ecological
significance of human acitivity it is necessary
to understand how the marine environment react to
ecological disturbances and changes in the
environment. It is particularly important to
understand the temporal and spatial scales for
which the changes are relevant. The analysis To
judge whether ecological changes are responses on
manmade disturbances or only general climatic
changes, very rigorous experimental designs as
well as extensive monitoring are necessary. At
the same time, it is important to assess with
which statistical power the various types of
changes can be detected.
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IMPACTS FROM DISTURBANCES, POLLUTION, AND
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• Chapter 14 executive summary
• Disturbances of marine ecosystems have occurred
  naturally in all places at all times.
• Responses on disturbances in terms of species
  diversities appear general and predictable
• Anthropogenic effects must be distinguishable
  from natural changes (by experimental design)
• The continental shelves are most sensitive to
  anthopogenic disturbances (fisheries,
  aquaculture, oil
• industry, shipping, tourism and pollution)
• Eutrophication caused by agriculture activity
  have resulted in poisonous algae blooms and mass
• deaths of marine fauna.
• Resistant pollution (e.g. plastics) have
  complex and hard-to-detect damage effects
• The consentration of the world population in
  coast-near areas makes them vulnerable to changes
  in
• the ocean level caused by man-made global
  warming

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The problem...
The increasing world population puts pressure on
natural resources, both terrestrial and marine.
The world has an increasing demand for
protein. The need for energy has increased
dramatically, too, and the use of fossile fuel is
believed to be one cause of the rapid global
warming we are witnessing today. It must be
expected that the need for energy will increase
even more, as new and large population groups
demand their share of the welfare.

World population in year 2000 was ca 6 billions.
The increase has been exponential for a long
time.
Year Population(in billions)
2010 6.8
2020 7.6
2030 8.3
2040 8.9
2050 9.4
Today the increase is approx. 1.2 p.a.
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The geographic distribution of the world
population shows that the densiest areas are
those where the inhabitants now demand their
share of the welfare, and therefore will need
huge resources in form of food and energy. It is
expected that this will lead to large milieu
problems in those areas, and an increased
pressure also on natural marine resources.
Population densities vary between countries. Some
nations have large populations and therefore
strong national interests relative to natural
resources and energy. India and China are typical
examples of this.
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Population densities in year 2000
"Hotspots" in population densities are found in
both developed and undeveloped countries.
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DISTURBANCES
Definition Disturbances were defined by Picket
White (1985) as "any time-limited event which
tears up existing ecosystems, societies or
population structures and changes resources,
substrate availability or the physical
environment". Natural Distubances act on
different scales and with different frequencies.
Natural disturbances, such as ocean-level change,
ocean temperatures and ocean currents, usually
take place over extended time periods. Other
natural phenomena have a shorter time scale
(hurricanes and cyclones, pests). Antropogenic
Oil spill, destruction of coral reefs by
trawling, eutrophication, and poisonous vaste.
Common to both is that they can affect a wide
specter of marine habitats, and that they are
processes which contribute to the diversity in
all ecosystems.
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The increased exploitation of natural resources
needed to serve a growing world population has
both direct and indirect disturbing effects on
marine ecosystems. Even activities far from the
ocean, like hydropower plants, mountain mining
(river-transported pollution), nuclear power
plants (leakage of radionucleotides), and
chemical industry (river-transported vaste)
eventually ends up affecting marine habitats and
ecosystems. A more subtle and slow-working
impact, but not less serious, is the increasing
deforestation several places on earth. It leads
to soil-erosion and increased river-transport of
soil, humus and mud which may cover benthic
habitats, and reduced light conditions in areas
with coral reefs. Reduced light can also lead to
changes in the composition and hierarchy of
marine food webs (example the coronate jellyfish
Periphylla periphylla). These anthropogenic
disturbances of biological systems come on top of
the natural fluctuations. The new danger now is
that mankind with its activities also affects the
climate, and thereby the natural fluctuations.

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Scale There is a tight coupling between the
time- and space scales in which disturbances
occur. On the smallest scale we have the
instantaneous chemical reactions between sediment
particles, viral-, and bacterial processes.
Futher on via minute-scale predation and
metre-scale bioturbidity to tidal cycluses. The
seabed is a mosaic of small societies on
different stages of change and recolonization,
and together these societies characterize the
habitat.
The physical disturbance which results from a
single waving crab (Uca sp.) is negligible, but
the joint activity of a whole population can turn
the sediment surface upside down during one
single tidal cyclus.
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Restitution rates For small-scale disturbances
the restitution times are short from seconds to
weeks, but they increases strongly with the
geographic and temporal scale. It may take years
and decades to heal the damage to a coral reef
which has been destroyed by bottom trawling. When
the fish fauna in coastal waters in South Norway
was almost wiped our some decades ago, it took
surprisingly short time (one or two years) before
it was intact again. Therefore, aspects of the
mobility of the involved organisms is also part
of the picture with respect to recolonosation.
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Different models have been suggested to describe
how animal societies react on a disturbance, in
form of changes in the societiy's species
diversity. Her are two of them
Pearson Rosenberg model
The IDH hypothesis (Intermediate Disturbance
Hypothesis)
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How to measure effects of human activities
One-variable indexes Variation in the
occurrence of one particular species has often
been used to describe the effects of
disturbances. However this approach does not
target changes in the very structure of the
society which results from the variation in one
or a few species. In most cases the effects of
human activity are not species-specific, but may
have very different effects on the various
components of the society. Wrong scale in the
approach can easily lead to wrong conclusions.
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Distribution indexes Measures which comprises a
set of species counts in a single sample in one
graph or histogram. There are a rich flora of
such indexes, whereof some may be more sensitive
and thereby better fit than others, depending on
the circumstances. The graph to the right shows
a situation where a plot of "Taxonomic
distinctness" (?) proved more effective than the
common Shannon-Wiener diversity index (H). Cf
the textbook page 469
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Multivariate techniques These techniques
combine two or more samples with respect to which
degree they contain the same species or different
species with variable frequency. They can include
both the species themselves, or their respective
occurrence or biomass). The graph to the right
shows a MDS (multidimensional scaling) plot of
fish and benthic societies in the Irish Sea by
use of bottom trawl. Closeness on the plot means
similarity of species composition and numeric
value.
MDS plott
(MDS plot. Cf textbook p. 470 for figure
caption). (Multi-Dimensional Scaling)
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• How to detect changes
• If we shall have any possibility to detect
  effects of human avtivity it is, in light of the
  enormously complex interactions in marine
  ecosystems, critically important to ask the right
  question. Long-term ecological changes are
  strongly influenced by a fluctuating environment,
  and it can be very difficult to sort out the
  importance of single factors among a multitude of
  milieu effects. Sometimes it is necessary to do
  laboratory experiments as a support to time
  series of climatic or ecological data.
• Monitoring time series must be designed so that
  they have the necessary statistical power for
  detecting trends in a time series.
• Type I error To conclude with difference when
  there in fact is no difference.
• Type 2 error To conclude with no difference
  when there in fact is a difference.

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Special topics

• A priori hypothesis testing
• A posteriori hypothesis testing
• Significance level in multiple
• tests of the same hypothesis
• The importance of pilot studies
• and resampling
• Joint significance level from
• multiple tests (Fisher's omni-
• bus test)

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• Experimental design
• Experiments must be planned so that the data
  obtained are suitable for the relevant
  statistical procedures and tests. Examples of
  basic pre-requisites are
• If Anova is planned, at least replicate
  measurements are needed, so that a mean and
  variance can be calculated.
• 2. If frequencies of categorial variables are
  used, sample size is crucial for detecting
  significant differences.
• 3. If trend analysis (increase/decrease) is
  used, at least 6 plots are necessary for
  detecting significance at the 5 niveau.

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The cause of changes in marine ecosystems
River transport of terrestrial discharge
Estuaries are strongly influenced by the
freshwater runoff, and the materials which the
rivers carries with them to the sea. Worldwide,
ca 70 of the sediments are contributed by
rivers. Powerplants, agricultural discharge,
flood debris, size of the precipitation area and
estuary decide how strong the sedimentation is.
The big rivers in the world the Amazonas and the
Nile create enormous deltas which in historic
time have been important settling areas for
mankind and birth places of civilications. Eutrop
hication Rivers supply nutrients to the
estuaries, and initiate phytoplankton blooms
which may spread over vast distances with ocean
currents and thus result in substan- tial
downstream ecosystem disturbances.
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Powerplant constructions
Egypt The building of the Aswan dam resulted in
a temporary decline of Mediterranean fisheries.
It is assumed that the reduced transport of
phosphorous during dam construction eventuallly
was more than compensated by increased supply
from water plants downstream after the building
of the dam.
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Natural conditions / eutrophication
In the northern Gulf of Mexico, on the Louisiana
continental shelf just by the outlet of
Mississippi, there are large areas with anoxic
conditions in the bottom water in March-December.
The severity of the conditions may vary from year
to year.
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Oil- and gas exploitation on the ocean
floor Release of hydrocarbons and boreslam from
drilling platforms affects the surrounding
seafloor considerably. The effect is seen as a
gradient out from the platform, some places out
to 100 meters, but in the North Sea up to 6 km.
Such releases have been substantially reduced
with modern technology, so that today the effects
from release from shipping is actually much
larger that the one from oil production.
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OIL SPILL
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OIL SPILL
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OIL SPILL
Oil in water affects plankton, nekton, (incl.
fish), aquaculture, birds and marine mammals.
Oil on the beaches affects coastlines, marinas,
freshwater production and seabirds and other
animals that live by the sea.
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OIL SPILL
The oil tankship Exxon Valdez was grounded on
Bligh Reff at the Kodiak Island, Alaskan Gulf 24.
March 1989. It released large amounts of raw oil
into the marine nvironment.
Exxon Valdez
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OIL SPILL
The Exxon Valdez oil spill killed, with
certainty, more than 1000 sea otters along the
west coast of USA. Some estimates suggest that
the number was actually three times larger. This
catastrophy, and many others, has had serious
consequences for endangered sea otter stock
wherever they are found.
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Amoco Cadiz
The tanker Amoco Cadiz grounded and spilt large
amounts of oil on the beaches of Bretagne,
France, in March 1978.
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Amoco Cadiz
Gannet killed by oil spill
Oil destroys the isolating effect of the birds
plumage and the birds flying ability. The bird
will freeze to death, be caught by predators
(incl. domestic pets), or succumb by poisoning.
Seagull, killed by oil spill
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OIL SPILL PHYSICS
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OLJESPILL
Plankton is the fundament of all marine food
webs. Plankton is very sensitive for the toxic
oil products, and many planktonic organisms die
at high oil consentrations. Many other organisms
in the food web suffer when the plankton biomass
decreases. Fish has sensitive organs for
detecting oil and are often able to leave
contaminated areas if not caught in some way.
Juvenile fish are more vulnerable than adults,
and a decimation at this life stage will have
long-term effects on the stock. Predators in the
marine milieu, like scavengers, birds and man,
eat in turn the contaminated fish and accumulate
toxic compounds in the long run. Oil compounds
do not taste good, and both wild fish and farmed
fish may not hit the market and thus lead to
economic losses. Farmed fish are usually not able
to leave the contaminated areas and can be deemed
not edible. In open waters, marine mammals such
as whales often have the possibility to leave
contaminated areas and thus reduce the danger to
their health themselves. However, those that live
closer to the shore (dolphins and seals) risk
contact with oil compounds on the shores, and get
fur damage and food toxification as a resulst.
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MINERAL MINING ON THE OCEAN FLOOR
Exploitation of mineral aggregates (nodules) from
the deep ocean floors results in intense local
disturbance which can last for decades.
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Contaminants
The most important contaminants are
radionucleotides and organic compounds from
energy plants and the industry. PCB
(polychlorated biphenyls) are shown to reduce
hatchability in bird eggs, while toxic mercury
accumulates in birds feathers. Heavy metals
generally accumulate and have toxic effects high
up in the food chain (top predators like fish,
birds, polar bear), while fat-soluble dioxins
have toxic effects e.g. through mothers milk in
mammals. Different flame-inhibitors are shown to
give hormonal disturbances in fishes, and may
lead to disturbances in sexual expression
(gender benders). Radioactive compounds fra
nuclear plants have leaked to the sea and led by
ocean currents long distances in the East
Atlantic. Leakages from the English nuclear plant
Sellafield have been traced in plant- and animal
tissues even in the inner parts of Norwegian
fjords.
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Climate change
The UN climate panel has concluded that the
ongoing worldwide temperature increase is an
effect of human activity in form of release of
climate gases (carbon dioxide, methane a.a.) and
water vapour. In the North Sea and along the
Norwegian coast there is an ongoing rise in
temperature which is unusually strong.
Temperature rises have also been recorded earlier
(e.g. in the 1930ies), and it is at present not
clear if we have entered an irreverible process.
The high coastal temperatures are also reflected
in increased bottom water temperatures in the
Trondheims-fjord during the last 30 years. (next
slide).
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DISTURBANCES
From the TBS hydrographical time series in the
Trondheimsfjord
The temperatures have oscillated ( 8-10 year
ampl.), with an upgoing trend In the last 10-12
years. In 2007 an all times high was recorded
at 500 m depth. The situation in the fjord
reflects that on the coast.
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DISTURBANCES
Ocean currents in the East Atlantic connects the
various regions and make no area isolated from
the others. Thus, all types of pollution can
reach even the northernmost regions. For example,
dioxins have reached alarming consentrations in
polar mammals and birds.
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Interaction between factors
In the foregoing, different factors that
influence the marine ecosystems have been treated
separately for the sake of simplicity. In reality
they often work in concert, and the effect can be
additive or synergetic. It is notoriously
difficult to predict the end outcome of the
change in one factor in an ecosystem, because the
interplay is so intense and complex between
organisms, and between organisms and their
environment. The outcomes may be very different,
dependent on the particular situation in time and
space. One knows about the occurrence of cascade
reactions, where originally small disturbances
can run away and lead to substantial
overthrowings in the ecosystems. Times with
extensive changes are Bonanza for opportunistic
species. Many of these are evolutionary very old
forms with simple life functions. Having survived
through hundreds of millions of years of
evolution, one can say that they have proved the
success of their design.