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🐠Marine Biology

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3.2 Marine biodiversity patterns and distribution

3 min readLast Updated on July 22, 2024

Marine biodiversity patterns are shaped by various factors, creating a complex tapestry of life in the oceans. Latitude, depth, and habitat complexity play crucial roles, influencing species distributions and creating hotspots of diversity in tropical regions and shallow waters.

Understanding these patterns is vital for conservation efforts and sustainable use of marine resources. From coral reefs teeming with life to the unique adaptations of deep-sea creatures, marine biodiversity supports ecosystem functioning, enhances resilience, and provides invaluable benefits to humans.

Factors Influencing Marine Biodiversity Patterns

Factors in marine biodiversity patterns

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  • Latitudinal gradient
    • Biodiversity decreases moving from equator to poles due to changes in temperature, solar radiation, and productivity
    • Tropical regions (coral reefs) have highest diversity while polar regions (Arctic Ocean) have lowest
  • Depth gradient
    • Biodiversity varies with water depth, highest in shallow, sunlit areas (coral reefs) and decreases in deeper zones
    • Bathyal zone has lower diversity but increases again in abyssal zone with unique deep-sea species
  • Habitat complexity
    • Structurally complex habitats (coral reefs, kelp forests, seagrass beds) support higher biodiversity by providing diverse niches and resources
    • Simple habitats (sandy bottoms, open ocean) have lower diversity due to fewer microhabitats and resources
  • Other factors
    • Temperature, salinity, and nutrients influence species distributions based on physiological tolerances
    • Ocean currents and upwelling zones affect nutrient and larval transport, impacting local biodiversity
    • Evolutionary history and geological events (Isthmus of Panama) shape regional species pools and endemism

Marine biodiversity hotspots vs coldspots

  • Biodiversity hotspots
  • Biodiversity coldspots
    • Relatively low species richness and endemism, often in polar and deep-sea regions (Arctic Ocean, Southern Ocean)
    • Harsh environmental conditions (low temperature, limited sunlight) and low primary productivity
    • Support unique species adapted to extreme conditions (ice algae, deep-sea vents)

Shaping of marine species distributions

  • Dispersal
    • Movement of individuals or propagules (larvae, seeds) enables colonization of new habitats and gene flow
    • Influenced by ocean currents, larval duration, and adult mobility (fish vs sessile organisms)
    • Long-distance dispersal events can connect distant populations and shape biogeographic patterns
  • Isolation
    • Separation of populations by physical or ecological barriers leads to reduced gene flow and potential speciation
    • Examples: isolated islands (Galapagos), deep-sea trenches, semi-enclosed seas (Red Sea)
    • Promotes endemism and unique evolutionary trajectories in isolated regions
  • Environmental gradients
    • Gradual changes in abiotic factors (temperature, salinity, depth) shape species distributions based on physiological tolerances
    • Leads to zonation patterns and distinct community assemblages (intertidal zones, deep-sea layers)
    • Species replacements and adaptations occur along these gradients (cold-adapted vs warm-adapted species)

Importance of marine biodiversity

  • Ecosystem functioning
    • Biodiversity supports ecosystem processes (primary production, nutrient cycling, carbon sequestration)
    • Higher diversity leads to increased productivity and stability through complementary resource use
    • Examples: diverse algal communities fix more carbon, seagrass beds stabilize sediments
  • Resilience
    • Higher biodiversity enhances ecosystem resilience to disturbances through functional redundancy and complementarity
    • Diverse systems better equipped to adapt to environmental changes (climate change, invasive species)
    • Examples: coral reefs with higher diversity recover faster from bleaching events
  • Importance for humans
    • Marine biodiversity provides valuable resources (food, medicine, raw materials)
    • Supports livelihoods and economies through fisheries, tourism, and other industries (aquaculture, biotechnology)
    • Offers cultural, recreational, and aesthetic benefits (diving, beach visits, traditional practices)

Key Terms to Review (29)

Abyssal zone: The abyssal zone is the deep-sea environment that lies between approximately 3,000 and 6,000 meters below the ocean surface, characterized by extreme conditions such as high pressure, low temperatures, and complete darkness. This zone is home to a unique array of organisms that have adapted to thrive in its harsh conditions, contributing to the overall patterns of marine biodiversity and the complex habitats found in the deep sea.
Bathyal zone: The bathyal zone is a layer of the ocean that lies between 1,000 and 4,000 meters below the surface, characterized by its cold temperatures, high pressure, and limited light penetration. This zone plays a crucial role in marine biodiversity patterns and distribution, as it serves as a habitat for various unique organisms adapted to the deep-sea environment. The bathyal zone is significant for understanding how different species thrive in extreme conditions and how these ecosystems connect with shallower waters.
Biodiversity hotspots: Biodiversity hotspots are regions that are both rich in endemic species and experiencing significant habitat loss, making them critical areas for conservation efforts. These areas support a high level of unique plant and animal life, while also facing threats from human activities such as urbanization and climate change. Protecting biodiversity hotspots is essential for maintaining global biodiversity and ecosystem health.
Biogeographic patterns: Biogeographic patterns refer to the distribution of species and ecosystems across geographical spaces and how these distributions change over time. These patterns help in understanding the relationships between organisms and their environments, which are influenced by factors such as climate, ocean currents, historical events, and human activities.
Carbon Sequestration: Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide to mitigate climate change. This process can occur naturally through ecosystems like forests, wetlands, and oceans, or through artificial means such as technology that captures carbon emissions from industrial sources. The effectiveness of carbon sequestration is closely linked to the health and function of various ecosystems.
Caribbean Sea: The Caribbean Sea is a tropical sea located in the western Atlantic Ocean, bordered by Central America to the west and south, and the Greater and Lesser Antilles to the north and east. This region is known for its rich marine biodiversity, including coral reefs, mangroves, and a variety of fish species, making it a crucial area for studying patterns of marine biodiversity and distribution.
Coral reefs: Coral reefs are diverse underwater ecosystems made up of colonies of coral polyps that build calcium carbonate structures, providing habitat and shelter for a wide variety of marine life. They play a crucial role in marine biodiversity and serve as essential components of coastal protection, nutrient cycling, and fishery support.
Coral Triangle: The Coral Triangle is a marine area located in the western Pacific Ocean, encompassing parts of Indonesia, Malaysia, Papua New Guinea, the Philippines, Solomon Islands, and Timor-Leste. It is recognized as the global center for marine biodiversity, hosting an unparalleled variety of coral species and marine life. This region plays a crucial role in understanding patterns of marine biodiversity and distribution due to its unique ecological characteristics and high levels of species richness.
Depth Gradient: The depth gradient refers to the gradual change in environmental conditions, such as light, temperature, and pressure, that occurs with increasing depth in marine ecosystems. This gradient plays a crucial role in shaping marine biodiversity patterns and distribution, influencing where different species are found and how they interact with their surroundings.
Dispersal: Dispersal refers to the movement of organisms from their place of origin to new areas where they can establish populations. This process is crucial for understanding marine biodiversity patterns and distribution, as it influences how species spread, colonize new habitats, and maintain genetic diversity. Dispersal mechanisms can include various strategies such as passive transport by currents or active movement by organisms, significantly shaping ecological communities in marine environments.
Ecosystem Functioning: Ecosystem functioning refers to the natural processes and interactions that occur within an ecosystem, including the flow of energy, nutrient cycling, and the interactions among organisms. These functions are essential for maintaining the structure and health of ecosystems, as they support biodiversity and contribute to the resilience of marine environments. Understanding how these processes work helps explain patterns of biodiversity distribution and the overall productivity of marine ecosystems.
Environmental Gradients: Environmental gradients refer to the gradual changes in environmental conditions over a certain distance or space, influencing the distribution and diversity of marine life. These gradients can include variations in temperature, salinity, light, nutrient availability, and depth, which create distinct habitats and ecosystems. Understanding these gradients is crucial for comprehending how marine biodiversity patterns emerge and how species are distributed across different marine environments.
Galapagos: The Galapagos Islands are an archipelago located in the Pacific Ocean, known for their unique biodiversity and significant role in the study of evolution. The islands are home to a variety of species that are not found anywhere else on Earth, making them a hotspot for marine biodiversity and a key area for understanding patterns of distribution and adaptation in marine environments.
Great Barrier Reef: The Great Barrier Reef is the world's largest coral reef system, located off the coast of Queensland, Australia. It spans over 2,300 kilometers and consists of approximately 2,900 individual reefs and 900 islands. This natural wonder not only showcases a diverse array of marine life but also provides critical insight into coral reef formation, ecological interactions, and the distribution of marine biodiversity.
Gulf of Guinea: The Gulf of Guinea is a northeastern part of the Atlantic Ocean, bordered by several West African countries including Nigeria, Ghana, and Ivory Coast. This region is known for its rich marine biodiversity and plays a significant role in the distribution and patterns of marine life due to its unique environmental conditions, such as upwelling zones and warm waters that support diverse ecosystems.
Habitat complexity: Habitat complexity refers to the structural diversity within an environment, encompassing the variety of physical features, such as the presence of rocks, plants, and substrates that create different niches for organisms. This complexity is crucial because it can enhance biodiversity by providing various habitats and resources that support a greater number of species. The relationship between habitat complexity and marine biodiversity patterns is significant, as more complex habitats often lead to higher species richness and abundance.
Ice algae: Ice algae are microscopic plants that grow on and within sea ice, primarily in polar regions. They play a crucial role in the marine ecosystem by contributing to primary production, influencing nutrient cycling, and serving as a food source for various marine organisms, highlighting their significance in marine biodiversity patterns and distribution.
Indo-Pacific: The Indo-Pacific is a vast region that encompasses the Indian Ocean and the western and central Pacific Ocean, extending from the eastern coast of Africa to the shores of the Americas. This area is known for its rich marine biodiversity and serves as a critical zone for ecological interactions, making it an essential focus for understanding marine biodiversity patterns and distribution.
Invasive Species: Invasive species are organisms that are introduced to a new environment where they are not native, and they often cause harm to the local ecosystem, economy, or human health. They can disrupt food webs, outcompete native species for resources, and alter habitats, leading to significant ecological changes. The introduction of invasive species is a pressing issue that has widespread implications for marine biodiversity and ecosystems.
Isolation: Isolation refers to the process or state of being separated from others, particularly in terms of geographical barriers that limit the movement and interaction of species. In marine ecosystems, isolation can influence patterns of biodiversity and species distribution, often leading to unique evolutionary paths for organisms that are cut off from larger populations.
Kelp forests: Kelp forests are underwater ecosystems formed by large, brown macroalgae known as kelp, which can grow into towering structures that provide habitat and shelter for a diverse array of marine life. These forests play a crucial role in coastal environments, influencing biodiversity patterns and contributing significantly to the productivity of marine habitats across different ocean basins.
Latitudinal Gradient: The latitudinal gradient refers to the variation in biodiversity and species richness observed across different latitudes, generally indicating that biodiversity tends to increase as one moves from polar regions towards the equator. This pattern is significant in understanding how environmental factors such as climate, temperature, and productivity influence the distribution and abundance of marine species.
Nutrient Cycling: Nutrient cycling refers to the process through which essential nutrients move through biotic and abiotic components of an ecosystem, allowing for their continuous availability to living organisms. This cycle is crucial for maintaining ecosystem productivity, health, and resilience, as nutrients are transformed and transferred through various biological and chemical processes.
Primary Production: Primary production is the process by which autotrophic organisms, primarily plants and phytoplankton, convert inorganic substances into organic matter using sunlight or chemical energy. This foundational process is critical for the energy flow in ecosystems, influencing nutrient cycling, supporting diverse marine life, and shaping overall biodiversity patterns in various habitats.
Red Sea: The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and the Arabian Peninsula. It is known for its unique biodiversity and distinct ecological characteristics, which contribute to the distribution patterns of marine life in this region. The Red Sea serves as a critical habitat for various species, ranging from corals to fish, making it an important area for studying marine biodiversity and ecological interactions.
Resilience: Resilience refers to the capacity of an ecosystem or community to withstand disturbances and recover from them, maintaining essential functions and structure. In marine environments, resilience is crucial as it enables ecosystems to adapt to stressors such as climate change, pollution, and overfishing while preserving biodiversity and ecological balance. A resilient ecosystem can bounce back from events like coral bleaching or habitat loss, thus sustaining its biodiversity and supporting the services it provides.
Seagrass Beds: Seagrass beds are underwater ecosystems formed by seagrass, a type of flowering plant that grows in shallow marine waters. These habitats play a crucial role in coastal environments, providing essential ecosystem services such as nursery grounds for fish and invertebrates, carbon sequestration, and stabilization of sediment. Their complex structure offers habitat and shelter to numerous marine species, significantly influencing the behavior and ecology of various marine life.
Southern Ocean: The Southern Ocean, also known as the Antarctic Ocean, is the ocean surrounding Antarctica, extending from the coast of the continent to 60 degrees south latitude. This ocean plays a crucial role in regulating global climate and ocean circulation patterns, serving as a unique habitat that supports diverse marine life and is vital for understanding patterns of marine biodiversity and distribution.
Tropical regions: Tropical regions are areas of the Earth that lie between the Tropic of Cancer and the Tropic of Capricorn, characterized by consistently warm temperatures and high levels of precipitation throughout the year. These regions are crucial for marine biodiversity, as they host some of the most diverse ecosystems, including coral reefs and mangroves, contributing significantly to global marine life and ecological balance.
Abyssal zone
See definition

The abyssal zone is the deep-sea environment that lies between approximately 3,000 and 6,000 meters below the ocean surface, characterized by extreme conditions such as high pressure, low temperatures, and complete darkness. This zone is home to a unique array of organisms that have adapted to thrive in its harsh conditions, contributing to the overall patterns of marine biodiversity and the complex habitats found in the deep sea.

Term 1 of 29

Abyssal zone
See definition

The abyssal zone is the deep-sea environment that lies between approximately 3,000 and 6,000 meters below the ocean surface, characterized by extreme conditions such as high pressure, low temperatures, and complete darkness. This zone is home to a unique array of organisms that have adapted to thrive in its harsh conditions, contributing to the overall patterns of marine biodiversity and the complex habitats found in the deep sea.

Term 1 of 29



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AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.