Recording-2025-02-03T00:13:31.127Z

Plant Biomass in the Northern Hemisphere

• The northern hemisphere tends to have higher plant biomass.

  • This is partly due to the majority of landmasses being located here.

• Phytoplankton and zooplankton are also more abundant in temperate and coastal areas.

Exam Format

• No math is required for the exam.

• The format consists entirely of multiple-choice questions with no short answers.

Nutrient Profiles and Photosynthesis

• Vertical profiles of phosphorus (phosphate) and nitrate demonstrate low levels at the surface due to uptake by phytoplankton.

• As one moves away from the photic zone, residual nutrients are present since photosynthesis ceases.

• Photosynthesis Equation:

  • Reactants: Solar energy, carbon dioxide (CO2), water (H2O).

  • Products: Glucose and oxygen.

Important Ocean Gases

• Key gases in the ocean include nitrogen, oxygen, and carbon dioxide.

• Carbon dioxide can dissolve in water, forming carbonic acid, which can break down into bicarbonate ions.

  • Excess CO2 may lead to ocean acidification, resulting in reduced carbonate ions available for shell-building organisms.

  • Current ocean pH is slightly above 8, but it is decreasing, which is a concern as it approaches neutrality (pH 7).

Organic Carbon Components

• Particulate Organic Carbon (POC): Refers to larger organic particles.

• Dissolved Organic Carbon: Refers to smaller, dissolved organic particles.

• The photic zone (top 100 meters) is where most biological activity occurs.

• Only about 5% of organic carbon makes it to the bottom as sediments.

  • Some organic carbon is utilized by deep-sea organisms.

Light Absorption in the Ocean

• Light absorption decreases with depth (attenuated).

  • Longer wavelengths, such as red, are absorbed first.

• Color perception is predicated on the wavelengths that objects reflect (e.g., plants appear green because they reflect green light).

• A notable demonstration of light attenuation can be observed through scuba diving with a color chart.

Osmotic Pressure and Saltwater Fish

• Osmotic pressure drives water movement from areas of high to low concentration.

• Saltwater fish possess adaptations for high salinity, such as excreting salty urine.

• Energy expenditures are greater for moving organisms; they either need to eat more or have efficient metabolisms.

Feeding Mechanisms

• Different feeding mechanisms include:

  • Filter Feeding: Organisms filter nutrients from water.

  • Deposit Feeding: Organisms consume sediments totaling organic matter.

  • Foraging: Directly hunting or searching for food.

Biodiversity and Taxonomy in Marine Life

• Genus and Species Naming: Genus is capitalized and species is lowercase, both italicized.

• Recent changes in taxonomy, e.g., stingrays reclassified from Dasyatis to Hypanus.

Three Domains of Life

• The three domains recognized are:

  • Bacteria

  • Archaea

  • Eukaryota

• Within Eukaryota, classification progresses from kingdom to species.

Eukaryotic Kingdoms

• Eukaryotes include kingdoms such as:

  • Animalia

  • Fungi

  • Protista

  • Plantae

Prokaryotes and Eukaryotic Microorganisms

• Prokaryotes are single-celled and lack membrane-bound organelles.

• Examples include:

  • Heterotrophic Bacteria: Require organic substances for energy.

  • Autotrophic Bacteria: Can produce their own food.

• Important for the microbial loop—the cycling of nutrients in marine environments.

Algae and Sea Plants

• Algae Types:

  • Red Algae (Rhodophyta): Includes species like sea moss.

  • Brown Algae (Phaeophyta): Includes kelps, important for their size and habitat formation.

  • Green Algae (Chlorophyta): Includes chlorophyll a and b for photosynthesis.

• Flowering Plants: Seagrasses are true grasses that create diverse ecosystems and stabilize shorelines.

Invertebrates Overview

• Sponges (Porifera): Benthic, asymmetrical, and capable of filtering water for nutrients.

• Cnidarians: Characterized by stinging cells (nematocysts) with classes such as hydrozoans and scyphozoans.

• Ctenophores (Comb Jellies): Simple organisms that use cilia for locomotion and capturing prey.