Iron hypothesis and iron limitation^1.pdf

Iron

1. Date. 1/01/2024
University: Somali National University
Faculty: Science
Department: Marine Science
Subject: Chemical Oceanography
Presentation: Iron hypothesis and Iron limitation
Lecture: Abdirazak Mursal
Presenters: Group A

2. Group A: Members
•Nuradin Sharif Adan. ID: B2SC 271
•Abdullahi Hassan Farah. ID: B2SC 242
•Abdullahi Ahmed Mohamed. ID: B2SC 256
•Mohamed Mohamud Omar. ID: B2SC 297
•Abdinur Sharif Abdinasir. ID: B2SC 327
•Abdirahman Ibrahim Nageye. ID: B2SC 216

3. Iron hypothesis and iron limitation

4. Iron hypothesis and iron limitation
Contents
•Introduction
•What is Iron hypothesis and Iron limitation
•Historical Context
•Phytoplankton and Iron hypothesis
•Role and Importance of Iron in Biological systems and processes
•Iron in Photosynthesis
•Iron in Hemoglobin
•Iron Limitation in Oceans
•Why is Iron Scarce in the Ocean?
•Consequences Of Iron limitation
•Iron Supplementation
•Research Advances

5. Introduction
•The iron hypothesis isa theory that suggests that adding
iron to iron-deficient seawater can promote plankton
growth and affect the concentration of carbon dioxide in
the atmosphere.
•The iron hypothesis and iron limitation are concepts in
marine biology and environmental science. The hypothesis
suggests that iron availability plays a crucial role in
regulating phytoplankton growth in certain regions of the
ocean. Phytoplankton are microscopic plants that form the
base of the marine food web. According to the iron
hypothesis, increased iron concentrations can stimulate
phytoplankton productivity. This idea gained prominence
in the 1980s and 1990s with experiments like the Iron Ex
series, which showed that adding iron to certain oceanic
regions led to a significant increase in phytoplankton
abundance.

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•On the flip side, iron limitation refers to the idea that in some parts of
the ocean, phytoplankton growth is constrained by low iron levels.
Despite the abundance of other nutrients, such as nitrogen and
phosphorus, phytoplankton struggle to thrive without sufficient iron .
Understanding the iron hypothesis and iron limitation is crucial for
comprehending marine ecosystems and the global carbon cycle, as
phytoplankton play a pivotal role in carbon fixation and contribute
significantly to atmospheric oxygen production.

7. What is Iron
hypothesis and iron
limitation ?.
•Definition: The theory that suggests that
adding iron to iron-deficient seawater can
promote plankton growth and affect the
concentration of carbon dioxide in the
atmosphereis called Iron hypothesis.
•Definition: Iron limitation isa factor that
limits the growth of photosynthetic organisms.
Iron limitation can decrease photosynthetic
activity, and also can inhibit phytoplankton
growth and decrease their primary productivity.

8. Historical
Context
The origins of the Iron Hypothesis
can be traced back to the 1980s
and 1990s when scientists began
to observe peculiar patterns in
marine phytoplankton
distribution. The hypothesis
gained momentum through a
series of experiments and
observations:

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Early observations in the 20th century highlighted the importance of
iron as a nutrient for plant growth. In the 1930s, researchers noted low
iron concentrations in seawater, particularly in regions with ample
nutrients but limited phytoplankton growth. Initial experiments in the
1970s and 1980s tested the hypothesis that iron could be a limiting
factor for phytoplankton. The 1990s IronExexperiments, coupled with
concerns about the global carbon cycle and insights from paleoclimate
records, solidified the concept of the Iron Hypothesis. explaining how
iron availability influences phytoplankton productivity in certain oceanic
regions.

10. Phytoplankton and Iron hypothesis
•Phytoplankton are Microscopic marine organisms that form the base of the ocean food web.
•They are Responsible for half of Earth's oxygen production through photosynthesis.
•They Play a crucial role in absorbing carbon dioxide and mitigating climate change.
•The Iron hypothesis is Proposed by John Martin in the 1980s.
•Suggests that iron deficiency limits phytoplankton growth in these regions.
•Iron is essential for chlorophyll production,enabling photosynthesis
•It acts as a cofactor for enzymes involved in electron transport chains, influencing the plankton's
growth and productivity.
•Iron hypothesis suggests to add Iron in the Iron-deficient areas of phytoplankton with less Iron, as
Iron is crucial for the growth and productivity of phytoplankton, which is the base of the food web
and food chain, and necessary for biogeochemical cycles and ocean biological and ecological
ecosystems.

11. Role and Importance of Iron in
Biological systems and
processes
•Iron plays a vital role in biological systems, particularly in the context
of oceans and marine life. Here are some key aspects of the role and
importance of iron in biological processes within ocean ecosystems.
•Photosynthesis: Iron is an essential component of chlorophyll, the
green pigment in plants and phytoplankton responsible for
photosynthesis. Phytoplankton, being microscopic marine plants,
require iron for this fundamental process, which converts sunlight into
chemical energy.
•Phytoplankton Growth: Iron is a limiting factor for the growth of
phytoplankton in certain oceanic regions. Adequate iron levels are
necessary for the proliferation of phytoplankton, which, in turn,
influences the entire marine food web and carbon cycling.
•It also plays important role in Iron fertilization, Carbon fixation, Food
Web Dynamics, Biogeochemical Cycling, Ocean Fertility and e.t.c.

12. Iron in Photosynthesis
Role of Iron in Photosynthetic Pathways:
Iron is crucial component for photosynthesis
and chlorophyll synthesis in plants. It is a
central atom in the porphyrinring structure
of chlorophyll, whichhelps plants capture
light energy and convert it into chemical
energy.Iron is also essential for cellular
respiration and photosynthetic electron
transport.
Impact of Iron-deficiency and excessive Iron on Plant
Growth and Productivity:
Iron deficiency alters photosynthesis and promotes
chlorosis, or the yellowing of leaves.In broadleaves, iron
deficiency causes young foliage to be bleached, chlorotic,
or pale between distinctly green veins.
Iron availability in soils dictates the distribution of plant
species in natural ecosystems and limits yield and
nutritional quality of crops. excess iron can be toxic,
affecting root development and nutrient uptake.
Maintaining the right balance is essential for optimal
plant growth and productivity

13. Iron in
Hemoglobin
Significance of Iron in Hemoglobin: Iron is
crucial in hemoglobin, the protein
responsible for transporting oxygen in the
blood. Hemoglobin consists of four subunits,
each containing an iron ion at its core. This
iron ion binds to oxygen molecules, allowing
hemoglobin to pick up oxygen in the lungs
and release it to tissues throughout the body.
Relationship to Oxygen Transport: Iron's presence in
hemoglobin is essential for oxygen transport.
Hemoglobin, found in red blood cells, contains iron
atoms that bind to oxygen in the lungs. This binding
facilitates the transportation of oxygen through the
bloodstream to tissues, where iron releases the
oxygen for cellular use. The relationship is vital for
maintaining oxygen levels in the body and
supporting metabolic functions

14. Iron Limitation in Oceans
Overview of Iron Limitation in Marine
Environments:
Iron limitation in marine environments refers to
the condition where the growth of phytoplankton,
crucial microscopic plants at the base of the
marine food web, is constrained by low iron
availability. Despite an abundance of other
nutrients such as nitrogen and phosphorus,
certain oceanic regions exhibit limited
phytoplankton productivity due to insufficient
iron.
Impact on Phytoplankton and Ocean Ecosystems:
The impact of iron limitation on phytoplankton
and ocean ecosystems is significant and has far-
reaching consequences for marine life and global
biogeochemical cycles including:
Phytoplankton Productivity, Biodiversity, Nutrient
Cycling, Carbon Sequestration, Zooplankton and
Higher Trophic Levels, Biological Pump, Climate
Regulation and e.t.c.

15. Why is Iron Scarce in the Ocean?:
The scarcity of iron in the ocean, despite it being the fourth most
abundant element in Earth's crust, is a fascinating case of limited
availability due to several factors including:
•Low solubility in seawater:Unlike elements like sodium and chlorine,
iron forms strong bonds with other elements like oxygen and
hydroxide in seawater. This makes it highly insoluble, meaning it's
difficult for it to dissolve and stay suspended in the water column. As
you might imagine, a sink wouldn't be very useful if it was filled with
floating rocks, and similarly, iron remains locked up in these insoluble
forms, largely unavailable to plankton that need it to thrive.

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•Binds easily with organic matter and sinks: Organic matter from dead
organisms and other marine debris releases molecules like humicacid
and siderophoresthat bind readily with iron. These iron-organic
complexes become heavier and sink towards the seafloor, taking the
vital element out of reach of surface-dwelling phytoplankton. It's like a
treasure chest getting buried deeper and deeper every day.
•Limited sources:Unlike nutrients like nitrogen and phosphorus, iron
lacks readily available sources. Dust from land and upwelling from the
deep ocean are its main contributors, but these are like mere sprinkles
compared to the vast ocean's needs.

17. Consequences Of Iron limitation
•Consequences of Iron Limitation include :
•Limited Phytoplankton Growth:Iron is essential for chlorophyll
production, which fuels photosynthesis in phytoplankton. Without it,
their growth is stunted, impacting the entire marine food chain. It's
like a domino effect, starting with a tiny missing piece.
•Reduced CO2 Uptake and impact on Carbon Sequestration:
Phytoplankton play a crucial role in absorbing carbon dioxide from the
atmosphere. Iron limitation hinders this process, potentially impacting
climate change. Think of it like a broken brake on a runaway car –CO2
levels rise unchecked.

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•Impact on Zooplankton: Zooplankton, which feed on phytoplankton,
can be affected by changes in phytoplankton abundance. Alterations in
the availability of phytoplankton as a food source may have cascading
effects on zooplankton populations.
•Fishery Dynamics:Iron limitation can influence the availability of
plankton, a critical food source for many fish species. Changes in
phytoplankton abundance may impact the overall productivity of
fisheries and the distribution of commercially important fish species.
•Consequences of Iron Limitation also include decreased Ocean
Fertility, Biological Pump, Climate regulation and e.t.c.

19. Iron Supplementation
Approaches to Address Iron Deficiency
Approaches to Address Iron Deficiency include:
• Iron Fertilization Experiments and Purposeful Iron Addition:
• Research on Natural Iron Sources and Understanding Natural
Sources:
• Oceanic Circulation Studies, and Understanding Iron Transport
• Monitoring and Remote Sensing and Satellite Observations:
• Integrated Ocean Observing Systems and Data Collection
Networks:
• International Collaboration and Coordinated Research Efforts:
Challenges and Considerations
Addressing iron limitation in the ocean, whether through research,
experimentation, or potential interventions, is fraught with
challenges and considerations. Some key challenges and
considerations include:
• Ecological Impact and Unintended Consequences:
• Ethical Concerns and Manipulating Nature:
• Global Governance and Regulatory Frameworks:
• Scientific Uncertainty and Limited Understanding:
•Technological Limitations and Feasibility Challenges:
• Legal Frameworks and International Regulations:

20. Research Advances
•Research on the iron hypothesis and iron limitation in marine
environments continues to evolve. Here are some general themes and
potential advances up to that point:
•Iron Fertilization Experiments: Ongoing studies and experiments have
further explored the impacts of iron fertilization on phytoplankton and
ocean ecosystems. Researchers aim to refine our understanding of the
effectiveness and potential ecological consequences of this approach.
•Satellite Technology and Remote Sensing: Advances in satellite
technology have enhanced our ability to monitor phytoplankton
blooms and iron distribution in the ocean remotely. This allows
scientists to gather more extensive and detailed data on oceanic
conditions.

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•Integrated Ocean Observing Systems: The establishment and
improvement of integrated ocean observing systems worldwide
contribute to a more comprehensive understanding of nutrient
dynamics, including iron levels, and their impact on marine
ecosystems.
•Other advances in Iron hypothesis and iron limitation include Genomic
Studies, Climate Change Interactions, Biogeochemical Modeling,
Ocean Acidification Considerations, Paleoclimate Records, and
Collaborative International Initiatives

22. Conclusion
•In conclusion, the Iron Hypothesis and
the concept of iron limitation in marine
environments have been pivotal in
advancing our understanding of the
intricate relationship between iron
availability and phytoplankton
productivity in oceans.
•In this topic understanding the role of
Iron in Global Carbon Cycle and Climate
Regulation, Iron Fertilization Experiments,
Knowing Challenges and Considerations,
and the need of Advances in Research is
also important.