Marine Biology: Salinity and Species Distribution

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary component of seawater that contributes to its salinity?

Sodium chloride (correct)

Potassium

Calcium

Magnesium

How is salinity in seawater commonly expressed?

Milligrams per liter (mg/L)

Parts per million (ppm)

Percentage (%)

Weight in grams per kilogram (g/kg) (correct)

What is the average salinity of ocean water?

40 g/kg

30 g/kg

35 g/kg (correct)

45 g/kg

Which ocean is known to have a higher average salinity compared to the others?

Atlantic Ocean Signup and view all the answers

What factors contribute to variations in salinity across the oceans?

Rainfall patterns and evaporation Signup and view all the answers

What is a potential issue when studying individual environmental factors in a laboratory setting?

The unnatural environment may lead to abnormal responses. Signup and view all the answers

Which of the following factors can modify an organism's tolerance to salinity changes?

Temperature Signup and view all the answers

Why might observations on specimens from one locality not be applicable to an entire population?

Differences in genetic variation may occur across populations. Signup and view all the answers

What impact do high summer temperatures have on Semibalanus balanoides?

They prevent gamete maturation. Signup and view all the answers

What is a characteristic of species with bipolar distributions?

They are found in both hemispheres but not in the tropics. Signup and view all the answers

What can limit a species' success even if physical and chemical conditions appear suitable?

Presence or absence of other species Signup and view all the answers

What is a significant challenge in evaluating biological factors affecting species distribution?

Their evaluation is complex due to numerous interacting factors. Signup and view all the answers

Which of the following methods is suggested for species dispersal between poles?

Deepwater thermohaline currents. Signup and view all the answers

What aspect is critical to understanding the success and distribution of marine organisms?

Identifying interactions between population and environment Signup and view all the answers

What is a challenge in proving that a taxon is truly bipolar?

Different species may have been misidentified as bipolar. Signup and view all the answers

Why is it difficult for slow-moving marine species to disperse to the opposite pole?

The journey takes too long for one individual. Signup and view all the answers

What should researchers study first to trace the complex interactions affecting marine species?

Individual environmental variables Signup and view all the answers

What term is used to describe species that can withstand only a small variation in temperature?

Stenothermal Signup and view all the answers

What recent development has helped clarify the question of truly bipolar marine macro species?

Genetic studies. Signup and view all the answers

What type of resources could other species contribute that may be essential for another species to thrive?

Food, protection, or attachment surfaces Signup and view all the answers

What do changing temperatures and salinities at the poles cause in ocean water?

Water to sink. Signup and view all the answers

Which type of organisms generally have a wider temperature tolerance in marine environments?

Sessile organisms Signup and view all the answers

Which factor has the greatest effect on the geographical distribution of marine species?

Temperature Signup and view all the answers

What has been a misconception about the amphipod Themisto gaudichaudii?

It is the same as Parathemisto gaudichaudi. Signup and view all the answers

What is an isotherm?

A line on a map joining points of equal temperature Signup and view all the answers

How are major marine biogeographical regions generally categorized?

By temperature and endemic species Signup and view all the answers

What type of populations inhabit temperate waters characterized by seasonal fluctuations?

Boreal and antiboreal populations Signup and view all the answers

What primarily accounts for differences between oceanic populations?

Man-made canals and physical land barriers Signup and view all the answers

Which of the following is NOT a major marine biogeographical region mentioned?

Desert water populations Signup and view all the answers

What characterizes the southern boundary of the Arctic zone?

It is less distinct, linked with specific current convergences. Signup and view all the answers

Which temperature range defines the temperate sea areas?

Between 5°C and 18°C. Signup and view all the answers

What is the term for the colder parts of the temperate regions in the northern hemisphere?

Boreal zone Signup and view all the answers

Which factor largely determines the course of the surface isotherms in ocean regions?

The surface circulation of the water. Signup and view all the answers

How are the temperate zones in western oceans described compared to eastern oceans?

Narrow in the west and wider in the east. Signup and view all the answers

Which of the following does NOT represent a classic biogeographic subdivision of marine zones?

Northeast Pacific region Signup and view all the answers

What does the classification of a species as 'tropical' or 'warm temperate' imply?

It reveals temperature requirements and geographical distribution. Signup and view all the answers

The recent approach taken by Spalding et al. was based on what type of data?

Limited data from easily studied species groups. Signup and view all the answers

What is the primary source of seawater's composition?

Condensation of water vapor and volcanic activity. Signup and view all the answers

Which of the following is classified as a conservative constituent of seawater?

Chloride Signup and view all the answers

Which process primarily contributes to the addition of juvenile water to seawater?

Basalt flows into the seafloor. Signup and view all the answers

What is the nature of minor constituents in seawater?

They fluctuate due to biological processes. Signup and view all the answers

What effect is especially relevant to marine organisms due to changes in seawater composition?

Ocean acidification. Signup and view all the answers

How do biological processes influence the composition of seawater?

By absorption and release of solutes. Signup and view all the answers

Which of the following is NOT a source contributing to the addition of constituents to seawater?

Biomineralization. Signup and view all the answers

What is the maximum length that certain marine animals can reach in hadal zones?

8 to 10 cm or more. Signup and view all the answers

Study Notes

Seawater Environment and Ecological Adaptations

This chapter describes the physical and chemical properties of seawater, and how these affect marine organisms.
Water properties like temperature, composition, density, viscosity, pressure, illumination and movement all influence marine life.
Seawater is easier to live in than freshwater or land.
Plankton, such as gelatinous plankton, can exist in seawater because of the support provided by water.
Light is a limiting factor in the ocean, except in surface and shallow water.
Physical conditions in the ocean are relatively constant across large areas
Marine species have correspondingly wide distributions.
Changes in conditions happen gradually, allowing organisms to acclimatize.
Species with precise environmental requirements have a limited range.
Two major gradients of physical conditions exist in the ocean: geographically between tropics and poles, and depth-wise.
Pressure, temperature, illumination and salinity vary with depth.
The interplay of these factors affects species distribution.

Effects of Variation in Single Factors

Laboratory studies of single factors can be abnormal
Several factors often interact; for example, tolerance to salinity change is modified by temperature and vice-versa.
Observations in one location might not apply to an entire population.
Species can have a range of tolerance for each variable.

Biological Interactions

Organism-organism interactions are important—prediation can be too severe or competition for resources could be a limiting factor.
Species may not thrive if other species' presence or absence affect them.

Sea Temperature

High specific heat of water moderates temperature variations in the ocean.
Continual circulation and large capacity for heat absorption results in a small temperature range.
Temperature variation is geographically and seasonally variable but limited in the ocean.
Temperature has a significant effect on metabolic rates and activity.
Effects of temperature on physiology are important.

Temperature Variations

Highest sea surface temperatures are at the equator.
Surface temperatures in sheltered areas can get very high in summer.
Freezing point of seawater is lowered by salinity.
Extreme temperature differences are between 10 and 150°C, but in local areas, variations are much lower than these extremes.
Deep ocean layers below about 2000 meters are constantly cold (between -1.9 and 4°C).
Deep-sea hydrothermal vents have much warmer water.

Thermoclines

A sharp transition between the warmer upper layer and the colder lower layer of water
Occurs between 200 and 1000 m depth.
These zones commonly separate warm and cold water populations.

Temperature Tolerances & Biogeography

Species distribution is largely determined by the ability to tolerate temperature variations.
Some species are stenothermal (narrow temperature range), while others are eurythermal (wide range).
Distribution may shift seasonally due to changes in water temperature.

Biogeographical Zones

Classic divisions (Arctic, Antiboreal, warm temperate, etc) are used to define distribution.
These are based largely on observations of planktonic, fish and other readily measured organisms.
Surface-water temperature is used in the identification of geographical regions.

Seawater Composition & Salinity

Seawater composition is relatively stable.
Conservative constituents remain constant.
Non-conservative constituents can fluctuate due to organism influences.
The most common solutes are sodium and chloride (i.e., salt).
Salinity (S) is the measure of inorganic salts in grams per kilogram of seawater(expressed as parts per thousand).
Average salinity is approximately 35%.
Salinity values vary geographically due to freshwater input, evaporation, and precipitation.
Extremely high salinities can occur in landlocked estuaries.

Dissolved Gases

Nitrogen, oxygen, and carbon dioxide are common dissolved gases in seawater.
Warmer water holds less dissolved gas than cooler water.
Pressure increases with depth, which causes gases to become more soluble.
Oxygen is produced by photosynthesis and consumed by respiration.
Oxygen levels are highest in surface waters and decrease with depth, with areas of very low oxygen levels in the deep sea.
Deep ocean waters with low oxygen can be dangerous, since oxygen is required by many marine organisms.

Effects of Seawater Composition on Physiology

Temperature affects metabolic rates in most marine organisms, influencing feeding and overall activity levels.
Temperature affects reproduction (maturation of gonads, sperm, and egg releases).

Biological Role of Dissolved Organic Matter

DOM plays an important role in the carbon cycle and plays an integral food resource for many marine organisms.
Originates from dead organisms (plankton, microorganisms), secretions, and other organic compounds dissolved in solutions
Important in nutrient cycling and species distribution.

Dissolved Gases (specifically Oxygen)

Oxygen is crucial for most marine life.
High O2 levels in surface waters, decreasing with depth.

Physiological Effects of Water Pressure

Increasing depth increases water pressure.
Pressure changes affect organism morphology and physiology; particularly the gas-filled spaces.
Organisms adapt to pressure to regulate internal osmotic balance.
Pressure can affect swimming and other activities and is a significant factor in species distributions.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores key concepts of salinity in seawater and its impact on marine organisms. Learn about average salinity levels, factors influencing variations, and biological challenges related to species distribution. Perfect for students of marine biology or environmental science.