Freshwater Ecology Lab exam

how can plankton be used as bioindicators of ecosystem health?

Because they’re sensitive to various pollutants and nutrient inputs, changes in their populations manifest prior to changes in larger organisms 

what are some results of undesirable plankton?

Releasing toxins, produce unpleasant tastes and odours that are difficult to remove

Phytoplankton

plants like algae

zooplankton

animals like copepods

features used to describe and differentiate plankton

size

colour

shape

motile

unicellular/colonial/filamentous

cell wall types

food storage materials 

what is the function of a gas vacuole in phytoplankton

allow them to control their position in the water, can sink lower for more nutrients and then go higher for light

cyanobacteria: example and traits

example: microcystis of the order Chroococcales

• unicellular

• thin cell wall

• growth at high temperatures

• capable of massive blooms

• produce toxins apon cell death/lysis

what is this 

microcystis

chlorophyta example and traits

volvox

can be unicellular, filamentous, or colonial

can be motile or non motile 

what is this

volvox

what class do diatoms belong to

class bacillariophyta

diatom traits

thick silica cell walls

non-flagellated

unicellular

low temp and low light tolerant 

bloom in spring 

disadvantage of diatoms

only remain in suspension when conditions are turbulent because they’re so heavy

two orders of diatoms and how to determine

centrales and pennales

• centrales are discoid or cylindrical

• pennales are elongate with bilateral symmetry

euglenophyta example and traits

euglena

• unicellular and motile with flagella 

• spindle shaped and have several chlorplasts per cell

• euglena are facultative heterotrophs

• environments abundant with decaying matter such as shallow lakes and ponds 

Rotifera 

unsegmented and pseudocoelomates

ciliated apical region known as the corona 

muscular pharynx known as the mastax

cilia are used for filter feeding and locomotion

what is this

rotifera

what is this

stentor

what is this

paramecium

how does chlorophyll a make photosynthesis possible?

by passing its energized electrons onto molecules that manufacture sugars

how can chlorophyll pigments be quantified?

using spectrophotometric, fluorometric, or high pressure liquid chromatographic methods

the ratio of chlorophyll a to phaeophytin is an indicator of what?

the ratio serves as an indicator of the physiological condition of the phytoplankton. 1.7 is completely healthy and anything lower especially 1 indicates an unhealthy culture/degradation

what does chlorophyll a measure and why is it reliable?

used as an indicator of phytoplankton biomass, as it is the main pigment involved in photosynthesis and found in all PS organisms directly correlating to the amount of biomass of these organisms in the water

what is a bioassay

an experiment that uses living organisms or systems to determine the activity/diversity of the substance

What is LC50?

50% lethal concentration, this is the concentration that kills 50% of the organisms over a specified period of time

What is the NOEL

no observable effect level, where there was no observable effect on the organisms

What is an IC50

The inhibitory concentration, the concentration where 50% inhibition was noted

what are normal vs abnormal swimming behaviours of daphnia

normal would be characterized as a hop and sink movement using their second antennae for propulsion

abnormal would be deviation from this pattern, staying sunk in the water column or not swimming to the rhythmic jerk of the hop and sink movement

what is a spectrophotometer used for

measures the intensity of light of different wavelengths in the visible spectrum

why do you need to set the blank for the spectrophotometer? 

everything absorbs a bit of light, so if you want to determine the absorbance of the sample you don’t want to include the absorbance of the liquid that the sample is in 

what is a standard curve and what’s on each axis

plotting results for samples of known concentrations. Concentration on the x axis and absorbance on the y axis

what is the life cycle and morphology of lamprey?

eel like body with mouth full of rows of sharp teeth in a circle.

larval filter feeders in streams for several years, parasitic juvenile phase in lakes/oceans, migrate back to rivers/streams to spawn and then die

what methods were used to bring lamprey under control 

lampricide treatments of TFM to kill larvae in streams. Sterile male release technique. 

What is this and what’s it used for

Van Dorn sampler. Used for obtaining samples at discrete depths

what is Lugol’s solution

what samples should be placed in immediately after sampling to preserve microscocpic aquatic organisms

What is this and what is it used for 

Ekman dredge. Used for quantitative macrobenthos samples by takinga  scoop of known area from the bottom sediments 

what gear should be used to measure phytoplankton and zooplankton

tow nets and plankton nets, or the schindler-patalas sampler

what should be used for macrophytes

rakes

what should be used for benthos

ekman dredge