Chapter 5 Key Concepts

Measures of organismal response include whole- organism, behavioral, physiological, and biochemical factors.
Organisms respond to environmental change by reaching a new equilibrium through a process known as acclimation.
An individual may be able to acclimate to an environmental change, but there is a hierarchy of biological responses to increasing stress.
Aerobic scope is a measure of available energy to fuel activity, such as swimming, relative to a maintenance metabolic rate under changing temperature.
Scope for growth is a measure of the food intake that is available for growth and reproduction beyond the cost of metabolism.
Mortality rate can also be used as a measure of the effect of environmental change.
Changes in gene expression and protein composition of cells can be measured as a response to environmental change.
Temperature affects the latitudinal distribution of most marine species.
Homeotherms regulate their body temperature, whereas the body temperature of poikilotherms conforms to the external environmental temperature.
Homeotherms, some fish, and a species of sea turtle use restriction of circulation, insulating materials, and a countercurrent exchange mechanism to reduce heat loss to the environment.
In poikilotherms, metabolic rate increases with increasing temperature.
Poikilotherms respond to increasing temperature with a standard performance curve of increased performance, a maximum, and then declining performance as temperature increases further.
Poikilotherms can compensate for changes of temperature by means of an acclimation process.
Species living over different latitudinal ranges have evolved different performances over a range of temperature. These differences have consequences as sea-surface temperature changes.
Temperature stress can affect organisms in three ways: by limiting growth, by limiting activity via oxygen delivery, and by limiting enzyme and cell function.
Large temperature changes can reduce physiological performance by affecting physiological integration.
The seasonal extremes of temperature have different effects depending on the location of an individual within the latitudinal range of the species.
Climate change is exerting thermal stress at the low-latitude end of species ranges and permitting northward extension of ranges as warm temperatures extend to higher latitudes.
Embryonic and larval thermal tolerances may be key in understanding how ocean warming affects the fate of marine species.
Salinity can change rapidly, which may have detrimental effects on marine organisms.
Changes in salinity affect marine organisms through the processes of osmosis and diffusion.
Marine organisms regulate both inorganic and organic cellular constituents to adjust to changing salinity.
The body fluids of bony fish have low osmotic strength; therefore, fish must regulate salt content in full- strength seawater.
Oxygen is required by most organisms to oxidize energy-yielding compounds.
Although total oxygen consumption increases with increasing overall body mass, the mass-specific consumption of oxygen decreases with increasing overall mass.
Oxygen consumption rate is higher in animals characterized by higher levels of activity.
Some organisms are obligate anaerobes, but most organisms require oxygen. Aerobic animals, however, may rely on a varying mix of metabolic pathways with or without the need for oxygen.
Animals only a few millimeters thick rely on diffusion for oxygen uptake; larger animals have specialized organs, such as gills and lungs, for this purpose.
Animals respond to lowered oxygen by regulating oxygen consumption, but their eventual response to very low oxygen levels is to leave the habitat if possible or to reduce activity levels.
Animals requiring great amounts of oxygen or living in environments where oxygen is difficult to acquire may have blood pigments that greatly increase the blood’s capacity for oxygen transport.
Animals with blood pigments can respond to low oxygen levels by changes in the character of the oxygen-carrying molecule.
During low tide, many intertidal animals cannot obtain oxygen and resort to anaerobic pathways of carbohydrate breakdown.
The highest intertidal zone and oxygen minimum layers pose special problems for aerobic animals.
As global climate change increases ocean temperature, increased thermal stratification is leading to reduced oxygen levels in the sea.
Light in the ocean comes mainly from the sun. Sunlight is the source of photosynthesis in the surface layers and adds heat at the surface; it also allows animals to use vision to help them function.
Marine animals may detect images with the aid of a simple layer of sensory cells, lenses, concave mirrors, or even a structure functioning as a pinhole camera.
Vision relies on a series of pigments that filter and absorb light.
Color vision is widespread among vertebrates and invertebrates.
Light is an important cue in behavioral adaptation of marine organisms.
Bioluminescence, a widely distributed property among marine organisms, is produced by specialized structures in animals or by (symbiotic) bacteria.