Marine Ecology Final

An estuary formed when a river valley is flooded by rising sea levels associated with melting glaciers and the end of the last glaciation period is called  

Coastal plain estuary

An estuary that forms when sandbars or barrier islands are delivered and deposited by littoral drift in such a way as to semi-enclose an existing coastal embayment is called a  

bar-built estuary

Dissolved oxygen depletion common to deeper regions of fjords is caused by 

long water residence times

The kind of estuary with the largest river inflow relative to its tidal current velocity is a

salt wedge estuary

The relative importance of stratification and mixing can be represented by a nondimensional number called the 

Richardson number

In the northern hemisphere, wind blowing to the south will result in a net transport of water to the  

West

In situations where the length axis of a deep estuary is short relative to the length of the tidal wave, the tide acts as a/an 

Standing Wave

The velocity shear between the seaward flowing surface layer and the landward flowing bottom layer can result in the generation of  

Internal Waves

In vertically mixed estuaries, landward transport of salt occurs nearly entirely through 

Tidal diffusion

Inverse (salt plug) estuaries result when

evaporation exceeds freshwater inflows

The Arrhenius equation describes: 

the relationship between chemical reaction rates and temperature

If something passes through a 0.45 micron filter it is considered to be:  

Dissolved (not big enough to be a particle)

Redox chemistry is important in estuaries because (select all that apply): 

1. Estuarine water and sediments have fluctuating oxygen gradients 

2. Estuarine bacteria can use alternate terminal electron acceptors when oxygen is not present (yes 5 others) 

3. Changes in redox potential can affect greenhouse gas (CO2, CH4, and N2O) emissions from estuaries 

If you are studying a one-dimensional, two end-member, steady state system and notice that the concentration of a constituent has a linear relationship with salinity, it is likely: 

a conservative constituent

the estuarine turbidity maximum is NOT:

characterized by low sedimentation rates

Organic matter in estuaries can come from:  

1. Phytoplankton biomass transported from ocean water 

2. Terrestrial plants 

3. Resuspension of sediments into the water column 

5. In situ primary production 

Which of the following is NOT a phase in the decomposition of organic detritus in estuaries? 

Decomposition phase, where autotrophic organisms break down detritus 

Which of the following is NOT a microbial process that occurs in anaerobic environments? 

nitrification

Which two microorganisms commonly perform nitrification in estuaries? 

Nitrosomonas and Nitrobacter

What greenhouse gases can be emitted from marsh soils? (select all that apply) 

CO2, N2O, CH4

Phytoplankton in coastal systems typically account for at least what fraction of total primary production? 

1/2

Diagnostic photopigments are useful in phytoplankton taxonomy at the species level 

False, they are useful at the taxonomic level

Flow cytometry enables the assessment of estuarine phytoplankton based on what properties? 

size, fluorescence, and abundance

Which gene can be used to study eukaryotic phytoplankton diversity but not cyanobacteria diversity? 

18S rRNA gene

Picocyanobacteria are favored under all of the following conditions, except 

increased flow

Eutrophication is the ability of certain phytoplankton groups to exploit 
salinity regimes ranging from freshwater to the coastal ocean

False

The supply of which of the following nutrient elements can control estuarine and coastal phytoplankton primary production? 

Iron (offshore), Nitrogen, Phosphorus, Silicon

What is the “harm” in Harmful Algal bloom species? (Select all that apply)

Toxicity, Oxygen depletion (hypoxia/anoxia), Food web distribution

How can changes in river flow control the location of maximum phytoplankton production in an estuary?  

By controlling the flux of river-borne nutrients, salinity of an estuary, turbidity in an esturary, and influencing the residence time of water.

How do phytoplankton communities adapt to changing light conditions? (select all that apply) 

by varying their photosynthetic pigment composition, by changing species composition, and by migrating vertically

Why do phytoplankton often bloom in spring in temperate estuaries?

Nutrient inputs via river flow is often elevated in spring in temperate estuaries. Zooplankton growth and grazing is limited in spring by colder waters.  

How are increased global temperatures, combined with an enhanced hydrologic cycle, forecast to impact phytoplankton community structure and function? (Select all that apply) 

Warming will favor cyanobacteria production, changes to fresh water and nutrient inputs will alter productivity, changes to estuarine residence times will alter community composition

seagrasses evolved from

terrestrial plants

What is the most important environmental factor that determines how deep seagrasses can grow? 

Light availability in water.

In which latitudes do seagrasses have the smallest change in biomass with season?

tropical

Which aspects of plant morphology vary in order to increase the light-harvesting capability of seagrass?  

shoot density, leaf length and leaf width

Seagrass respiration is most strongly controlled by:

temperature

Nutrient uptake in seagrasses is primarily a function of: 

flow speed and nutrient concentration

Which nutrient is most often limiting for seagrass communities globally?

nitrogen

Submersed plant canopies reduce water flow within the meadow. Which of the following is a result of this interaction? 

suspended particle concentrations decrease within the meadow

Which of these is not an ecosystem service provided by seagrasses? 

reduce coastal water temperatures

Seagrass extent is monitored at many places worldwide. By what percentage is it estimated to have declined since the 1870’s? 

30%

Which group of benthic macroalgae can grow in the deepest water? 

Rhodophyta

Which taxa of microalga are the most dominant in shallow-water marine sediments?

diatoms

Which aspects of macroalgal morphology (shape & size) affect light harvesting and photosynthetic rates? 

chlorophyll, accessory pigments, and surface area: volume ratio

Which types of macroalgae are most likely to exhibit surge uptake when exposed to nutrients? 

fast growing bloom forming macroalgae

In which of these ways do benthic microalgae influence marine sediments? (Select all that apply) 

sediment stabilization, sediment oxygenation

How are microalgae in polar regions adapted to extreme seasonality in favorable growth conditions? (Select all that apply) 

shade tolerance and carbon stores

Which of these are negative effects of dense macroalgae communities on benthic faunal communities? (Select all that apply) 

increase sulfide concentrations and low dissolved oxygen

In which macroalgal communities is the grazing food web more important than recycling via the detrital food web?

Rocky intertidal

Benthic microalgae can compete with phytoplankton for which resource(s)?

nutrients

Animals that exist for their entire lives as plankton are called 

holoplankton

Most zooplankton exist at a Reynolds Number less than zero.  

false

Reynolds number is the ratio between which of the following? 

inertial and viscous forces acting on an object

Cryptic species are ones that 

cannot be identified as separate species by looking at their morphology

Which of the following lists has the zooplankton size classes ordered from smallest to largest? 

Microplankton, Mesoplankton, Macroplankton, Megaplankton

High turbidity, which is a common feature of many estuaries, can cause (Select all that apply) 

Detritus and non-phytoplankton material to be more important for zooplankton diets and high zooplankton concentrations in ETM

Zooplankton have been shown to avoid being washed out of estuaries during high flow events, such as floods from storms, by which of the following? 

Descending to the near bottom where the flow rate is low.

Which of the following are responses to deoxygenation or hypoxia in copepods? (Select all that apply)

Reduced vertical migration, increased horizontal migration, and reduced egg production

The word for an organism that can generate its own nutrition and also ingest nutrition is 

Mixotrophy

Invasive species can affect estuarine ecosystems in each of the following ways except 

change the salinity of the estuary

Selective Tidal Stream Transport is a method for larval meroplankton to

Use tidal currents and vertical migration to affect their horizontal movement into or out of an estuary

To which group of benthic animals does the following statement best apply? 

“Abundances typically range from 10⁵ to 10⁷ individuals m^-2 and biomass ranges from 0.2 to 1 gC m^-2 “ 

meiobenthos

Which group of benthic animals would you expect to have the fastest biomass turnover time? 

microbenthos

Let us say you sieve a sample from an estuarine sediment and that you examine the animals that are retained on a 0.5 mm sieve. What group of animals does this size range best describe? 

macrobenthos

How does bioturbation by benthic animals affect oxygen penetration into sediment? 

Bioturbation increases the depth to which oxygen penetrates into the sediment

Which of the following is true about the redox potential discontinuity? (Select all that apply) 

most benthic animals live above the redox potential discontinuity, hydrogen sulfide is found predominatly below the redox potential discontinuity

Benthic animals that use a regulating strategy as the external salinity fluctuates __________.  

maintain constant internal physiological conditions as the eternal salinity changes.

In heavily or grossly polluted environments, sediment-dwelling animals are more likely to _________ than animals in unpolluted environments. 

be smaller in body size

Bottom-water hypoxia has many effects on benthic communities. Which of the following statements are true? (Select all that apply) 

hypoxia alters the fate of energy in sediments because more of the energy entering the sediments is used by microbes and less is used by animals. Density of benthic animals decreases with increasing duration and intensity of hypoxia. Benthic animals may become lethargic under hypoxic conditions and predation by nektonic predators may increase.

Which statement about benthic animals and their sensitivity to hypoxia is true? (select all that apply) 

crustaceans and echinoderms are more sensitive than annelids and nematodes. hypoxic bottom waters drive a positive feedback loop that enhances hypoxia in sediments by eliminating bioturbators

Where would you expect to find the lowest species diversity of benthic animals in estuaries that span the range from fresh water to marine conditions? 

in the middle portions of estuaries with intermediate salinities

Nekton can swim and move independently of water currents. Examples of nekton include all of these animals except: 

adult copepod

Osmoregulation in estuarine fish is accomplished with many different physiological adaptations. These adaptations include all these except: 

consumption of prey with low salt content

Juvenile fishes are generally more salt tolerant than adult fishes 

false

Estuarine nekton generally migrate to avoid environmental conditions outside their physiological tolerances in all these factors except: 

sunlight

Nursery grounds in estuaries ______________ 

enhance the survival of juveniles

A study of habitat usage in European estuaries showed that most estuarine fish species use which habitats for feeding and nursery areas? 

subtidal hard and soft substrates and biogenic reefs

Nekton generally use multiple estuarine habitats during their life cycle for all these reasons except:  

to vary their diets

Winemiller’s ordination of life history strategies categorize fishes based on _________ 

Fecundity, at age maturity, juvenile survivorships

Nekton with an opportunistic life history strategy often 

spawn often

The life history of most estuarine nekton is  

a combination of strategies

Year class success in estuarine nekton depends on the combined effects of growth and mortality (Cushing’s single process) such that success is favored when fish 

grow more rapidly than their rate of mortality

Nekton growth rate depends on _________ 

temperature and amount of food consumed

What value is the most reasonable “rule of thumb” for estimating trophic transfer efficiency in estuarine food webs? 

10%

Which of the following functional trophic groups is quantitatively least important to energy flows in estuarine food webs? 

chemoautotrophs

What can cause estuarine biomass pyramids to become inverted? 

longer average lifespan of higher trophic level organisms

Which of the following is considered an indirect trophic interaction? 

predators consumes a grazer and its producer food increases

Top-down control in food webs refers to:

change in abundance of lower trophic level organisms caused by a predator

Nutrient uptake by leaves in seagrasses is primarily a function of: 

flow speed and nutrient concentration

Which of these are an ecosystem services provided by seagrasses? 

carbon sequestion, nursery for fish species, aesthetic and recreational values

on subtidal rocky reefs

ominant colonial invertebrates generally have lecithotrophic larvae, so recruitment only occurs over short distances

Many sessile species often coexist on rocky and coral reefs because

interspecific mechanisms of competition are complex and often non-hierarchical

Sponges fed by means of  

currents formed by collar cells

Torsion 

is an important feature of gastropods

Some echinoderms defend themselves with 

pedicellariae

Which of the following is not a cnidarian? 

comb jellies

which of the following are not arthropods

brachiopods

benthic sea squirts are most closely related to

the vertebrates