Marine Biology: Challenges, Plankton, and Benthic Ecosystems

What is the density of water compared to air?

Water density is 830 times greater than air.

What is the principle of continuity in fluid dynamics?

The product of velocity and cross-sectional area remains constant.

What does the Reynolds number (Re) represent?

Re = (Velocity)(size)(density)/Viscosity; it increases with velocity and size.

How does speed affect drag on larger objects moving through water?

Speed is squared in the drag equation, greatly increasing drag.

What is friction drag?

Drag produced by the collision of water on a surface, pulling back with turbulent flow.

What are the two types of tail fins in fish?

Homocercal (same shape on each side) and Heterocercal (not symmetrical, like shark tails).

What strategies do fish use to deal with sinking?

Reduce weight, have a cartilage bone structure, or live on the bottom.

What is the function of a gas bladder in fish?

It helps with buoyancy; Physostomus is open to the outside, while Physoclistous is sealed.

What is the difference between regulators and conformers in marine organisms?

Regulators maintain constant internal conditions, while conformers change internal states to match the environment.

How do elasmobranchs maintain osmolarity?

They maintain a high concentration of urea to have a higher internal osmolarity than seawater.

What are holoplankton?

Organisms that spend their entire lifecycle in plankton, such as diatoms and copepods.

What are meroplankton?

Organisms that spend only a portion of their life in plankton, typically bottom-dwelling or nektonic in adult form.

What are the main types of plankton?

Phytoplankton (autotrophs), Zooplankton (heterotrophs), Bacterioplankton (decomposers), and Virioplankton (viruses).

What is the significance of plankton in global photosynthesis?

Plankton account for less than 1% of total photosynthetic biomass but contribute to 50% of global photosynthesis.

What is the Redfield ratio?

The ratio of nitrogen to phosphorus in plankton is 16N:1P, while in ocean water it is 14.7N:1P.

What is a harmful algal bloom (HAB)?

A bloom that produces toxins, depletes oxygen, and can physically damage marine life.

What are the two main types of nektonic mammals?

Odontoceti (toothed whales) and Mysticeti (baleen whales).

What is the biological pump in the ocean?

The vertical migration of plankton and nekton that forces material downward into the deep sea.

What are the characteristics of poikilotherms?

They do not regulate body temperature, have low metabolic costs, and are susceptible to thermal damage.

What is the role of gills in fish?

Gills absorb oxygen from water; they can collapse when out of water.

What is the impact of hypoxic conditions on marine life?

Hypoxic conditions lead to anaerobic metabolism and metabolic depression, reducing activity and oxygen demand.

What are the sediment types based on origin?

Lithogenous (erosion of rock), Biogenous (produced by living things), Hydrogenous (precipitates from water).

What is the difference between epifauna and infauna?

Epifauna live on the sediment surface, while infauna live inside the sediment.

What is the significance of porosity and permeability in sediments?

Porosity refers to the space within sediments, while permeability indicates how easily liquid moves through them.

What are the two main strategies for combating sinking in plankton?

Adjusting bulk density and swimming behavior.