Focusing on the Large Marine Ecosystems (LMEs) of the world, this course will introduce the concept and practice of ecosystem-based management. LMEs occupy areas of coastal ocean at least 200 000 km² or greater in size. These coastal waters produce 12.6 trillion USD in ecosystem goods and services annually and are vitally important for billions of people around the globe. Because LMEs are bounded by ocean features and are globally linked, management of human activities needs to occur in an integrated fashion across political boundaries and economic sectors (e.g. fishing, shipping, energy, tourism, and mining.) This represents a new type of management approached - shifting from single sector-based to multi-sector assessment and management within the spatial domain of the world's 66 Large Marine Ecosystems. There is global high-level support for this new approach and in this course, we will introduce the concepts and tools for assessing and managing LMEs. Together, leaders and experts in a global movement to recover and sustain the goods and services of LMEs will introduce you to the mechanisms used for assessment (Transboundary Diagnostic Analysis), planning and implementation (Strategic Action Programme). Based on recent activities in implementation and practice of the LME approach in 22 projects around the globe, we will showcase examples of effective management at this scale, and highlight the challenges and issues. By the end of the online course, we hope you will be able to actively use this knowledge to advance sustainable development of the world’s oceans. The course was created with the support and input of: the Global Environment Facility (GEF), the United Nations Development Program (UNDP), the National Oceanic and Atmospheric Administration (NOAA), UNESCO-IOC and IW:LEARN.
The productivity module
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Do curso por University of Cape Town
Large Marine Ecosystems: Assessment and Management
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The Three Natural Science Modules
In this week, we deal with the three natural science modules within the five module approach.
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Coleen MoloneyAssociate Professor
Marine Research Institute
The productivity module is part of
the five module framework of the large marine ecosystem approach,
and it concerns the importance of monitoring
ecosystem productivity with a focus on primary production.
The main primary producers in the ocean are microscopic organisms,
collectively called phytoplankton, but they comprise two main groups,
photosynthetic cyanobacteria, which is a group that was responsible for
creating Earth's oxygen-rich atmosphere some 2.4 billion years ago,
and single-celled or chain-forming microalgae.
These tiny organisms are hardly visible even with the microscope,
but they support two key ecosystem services,
the cycling of elements necessary for
all living organisms on Earth and the provision of food.
In the productivity module,
we consider how impacts on
these marine microorganisms can lead to issues in the rest of the ecosystem.
Phytoplankton are important in
biochemical processes that influence the entire biosphere.
They produce about half the oxygen that makes the Earth's atmosphere
suitable for life and are also important in the carbon cycle,
because during photosynthesis, they absorb
dissolved carbon dioxide from seawater and incorporate it into living tissue.
This carbon then either can be released back into
the seawater by respiration or it can be transformed into
other living material by being grazed or it can be lost by
sinking to the depths of the ocean where it can remain for a long time.
The last of these possibilities represents something known as the biological pump,
through which phytoplankton provide an ecosystem service by helping remove
the excess carbon dioxide from the atmosphere and pumping it into deep water storage.
Phytoplankton also power the entire marine food web.
They are eaten by microscopic animals called zoo plankton,
which in turn are eaten by larval fish and forage fish like sardines,
anchovies, herrings, and mackerels.
The forage fish serve as food items for predators in the food web,
like larger fishes, squids,
sharks, seabirds, and marine mammals.
How much primary production there is at the base of the food web
determines the capacity of the ecosystem to support organisms near the top,
such as fish populations that supports artisanal and industrial fisheries,
as well as other forms of marine biodiversity like marine mammals and seabirds.
In this way, the primary producers impose
what is known as bottom-up controls on food webs,
and they determine overall ecosystem productivity,
because changes in the magnitude of
primary production are promulgated up the food web from the bottom levels,
affecting the organisms at the high trophic levels.
In healthy ecosystems, if there is large primary production,
then there is potentially more energy available to
transfer to fishes and higher trophic levels,
and this leads to potentially large fisheries catches.
The converse is also true.
Marine ecosystems that have reduced
primary production also tend to have reduced fisheries catches.
The levels of primary and ecosystem productivity can thus be used to
help group large marine ecosystems and to study similarities and differences among them.
In unhealthy ecosystems,
excessed primary production can result from high nutrient loads in the coastal ocean,
which receives these excess nutrients as runoff from agriculture and industry,
and this leads to something called coastal eutrophication,
which is linked to the development of
harmful algal blooms and the depletion of oxygen in the seawater.
In contrast to this anthropogenically caused increase
in primary production in coastal waters,
climate change is likely to cause decreased primary production in oceanic waters.
As the surface ocean heats up in a warming world,
the water becomes less dense.
This makes the surface water less likely
to mix with the cool dense waters that lie below,
which are the source of nutrients for primary production.
Global warming is thus likely to reduce the overall global primary production,
which will have an impact on high trophic level organisms and also on fisheries catches,
changing both the amounts and the kinds
of fishes that are available to be caught by humans.
Global warming also has another effect.
It's likely to decrease the efficiency of the biological pump.
Because carbon uptake in the surface waters is decreasing,
the transport of carbon from the surface to the deep ocean is also decreasing,
which exacerbates the accumulation of carbon dioxide in the atmosphere.
Primary productivity can be used as an indicator of ecosystems state,
showing the potential carrying capacity for fisheries or as
a measure of ecosystem stress as occurs during harmful algal blooms.
Indicators of changing ecosystem productivity use variables
that either represent primary production,
such as chlorophyll concentrations in the sea,
or that influence primary production,
such as light, nutrients, and temperature.
Data collected by satellites can be used to estimate
chlorophyll concentrations and temperatures in the ocean's surface waters,
and these provide an archive that can be used to derive indicators of the state of
the ecosystem and of ecosystem productivity in different regions and at different times.
You will need to be familiar with these and other indicators to
complete your assignment for this and for following weeks.
So, in summary, the productivity of an ecosystem determines
its capacity to support fisheries and is also linked to vital ecosystem services.
Indicators are used to assess and monitor
ecosystem state and health and are important for
determining the carrying capacity of
the large marine ecosystem and its ability to deliver critical goods and services.
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