Water 1 Aquatic Ecosystems Flashcards
ecosystem
a composition of biotic communities that are structured by biological interactions and abiotic environmental factors.
autotrophs
organisms that use energy directly from inorganic sources, primarily using photosynthesis.
heterotrophs
organisms who receive their energy by consuming other organisms. This includes bacteria and fungi
three water body zones
littoral, pelagic, and benthic zones
littoral zone
shallow part near the shores, where most water plants are present.
pelagic zone
deeper open water part
benthic zone
sediment and direct surrounding water layer
where can you find bacteria and fungi
in the sediment, where there is dead organic material.
mineralisation
The breaking down of dead organic matter into inorganic compounds such as nutrients and CO2. This is done by bacteria and fungi.
primary producer
they are the first level of organic compound in an ecosystem. These are autotrophs,
What does photosynthesis control in an ecosystem?
the levels of oxygen and CO2 so they are in balance.
trophic levels/ food chain
the interdependence of trophic levels forms the food chain
phytoplankton
small, mircoscopic plantsthat live in open water. They can be seen if they are in large numbers and have chlorphyll.
which water conditions do phytoplankton prefer?
lakes over rivers, they do not live in fast flowing bodies of water.
3 groups of phytoplankton
diatoms, green algae, blue-green algae (cyanobacteria).b These are found in temperate surface waters.
diatoms
rapid growth rate in favourable conditions, so you tend to see yellow. Their cell wall is made of silica, so they are easily monitored, especially as the cell wal dissolves very slowly after the death of the cell.
Green algae
common, lack any form of special traits.
blue-green algae
cyanobacteria, they can form layers on the surface and produce toxins lethal to wildlife. Mostly, they are cosmopolite and present over the globe. They are highly dependent on environmental conditions.
periphytic algae
sessile (immobile) life under water. They form periphyton.
periphyton
a biofilm, consisting of algae, cyanobacteria, heterotrophic microbes, and detritus. Food source for inverterbrates, tadpoles, some fish.
epiphyton
periphyton biofilm growing on water plants.
filamentous algae
long green threads that are soft and loose. Separate algae species that develops well in spring. They can capture gas bubbles and float, forming a flab.
flab
floating algae bed.
other word for macrophytes
aquatic plants
now tell me about macrophytes
vascular plants, adapted to living in aquatic environment. They have adapted to limited light availability and gas exchange. Photosynthesis is slow but transpiraiton is fast.
Adaptations of aquatic plants/ macrophytes
- floating/ thin leaves to increase SA for gas exchange and light absorption.
- no plant cutile
- epidermal cells contain chlorophyll to increase light absorption.
- no stomata
- no/ reduced roots.
plant cutile
thin protecting film covering the plant surface.
plant stomata
tiny openings (mainly bottom of leaf) to allow gas exchange.
roots in aquatic plants
reduced/ no roots - nutrients can be obtained from water column. if roots, nutrients can be taken up from pore water in sediment.
zonation
the distribution of plants or animals into specific zones according to such parameters as altitude or depth, each characterized by its dominant species.
3 architectures of plant types
emergent, submergent, floating
helophytes
plants that grow in marshes, partly submerged by water, eg. Reed. They lack neither water nor CO2 and take up a lot of nutrients while growing. they are a biological filter to reduce the nutrient concentration in water.
floating macrophytes
These exist when waves are not too strong. In the tropics, you can get dense mats. duckweed is the most common in nl.
most visible aquatic fauna
fish and birds
protozoa
single celled microorganisms which feed on organic matter/ tissue and debris. They consume bacteria and small algae. Important food source for zooplankton
zooplankton
heterogeneous group of organisms in which the number of small animals is the largest.
purpose of zooplankton
transfer of organic material produced by phytoplankton to high er trophic levels and the control of phytoplankton populations.
zooplankton and food
they feed: filter feeding, predation and symbiosis with autotrophic phytoplankton.
They eat: bacteria, phytoplankton, other zooplanktonand detritus.
They are found in surface waters
Which pressures do zooplankton place on phytoplankton
they minimally influence algae biomass but Daphnia species pressure phytoplankton. These are water fleas (1mm) and therefore outcompete other zooplankton.
size of macrofauna
over 0.5mm and can be found with the naked eye.
macrofauna other terms
macrointvertebrates
inverterbrates <=> evertebrates.
description of macrofauna
include worms and arthopods and snails. Many insects have their egf and larvae stadium i the water. They are separated into the 4 ways in which they collect food.
4 types of microfauna
shredeers, collectors, scrapers/ grazers, predators
shredders
rough material into fine pieces. eg. amphipod & larvae
collectors
cosume fine organic pieces in two ways: filterers filter water and gatherers gather the pieces.
scrapers/ grazers
herbivores that graze organic material from the bottom, stones and plants, eg. snails.
predators
carnivores that eat other inverterbrates. eg. water beetles and dragonfly larvae.
benthic inverterbrates
macrofauna species that live in or around the sediment. Their habitat depends on aquatic plants.
physiological niche
preferred pH, temperature, nutrients, trace elements, stream velocity, oxygen and light climate.
EWF
European Water Framework Directive - mainly based on presence of aquatic inverterbrates.
organic materials
dead plants and animals from water and banks that are dissolved or float in the water.
humic and fulvic acids
intermediate products in the degradation of organic material.
saprobicity
measure of the quantity of organic matter.
polysaprobic
high molecular weight of organic matter, very little or no dissolved oxygen, abundant bacteria, few animals.
mesosaprobic
simpler organic compounds, increasing oxygen, few algae
oligosaprobic
zone of recovery where mineralization is complete and oxygen is back to normal, containigna wide range of plants and animals.
2 super important nutrients in water
nitrogen and phosphorous
the three degrees of eutrophication
oligotrophic -> mesotrophic -> eutrophic.
eutrophic water
highly enriched with nutrients, depleting oxygen levels.
hypereutrophic
environments characterised by murky, highly productive waters, covered in a layer of algae. Clear-water species can not survive.
respiration
O2 into CO2
anoxic
the situation by which oxygen levels are relatively low.
turbidity
the reduction in light strength when it penetrates in the water column
light attenuation
the absorption of light, dependent on absorption and scattering.
lambert-beer equation
Iz = I0 x e ^(-Ez)
what do the letters in the lambert-beer equation stand for?
Iz - light intensity at depth z
I0 - light intensity at surface
E - extinciton coefficient
z- depth.
Secchi disk
the black and white disk you let disappear until you can not see, where you reach the Secchi depth, which is roughly inversely proportional to the extinciton coefficient.
factors determining phytoplankton growth
nutrients limits algae
mechanisms that suppress nutrient concentrations
sedimentation, resuspension, flushing, light limitation, grazing by zooplankton
flagellates
things phytoplankton can swim with
thermal stratification in lakes
occuring in the summer, the lake is split into three sections, the top and bottom, separated by the metalimnion. This decreases nutrient levels in top layer.
What is the most important factor for vegetation growth?
light availability
Which factors affect light availability?
turbidity from suspended particles and periphyton
what is periphyton and how does it affect aquatic plant growth?
a layer of algae and bacteria. When nutrient concentration in a lake increases the growth of phytoplankton and periphytons increases. If grazers eat them, light availibility increases again.
how do water temperatures and sediment quality affect plant growth?
low temp = little growith
poor sediment quality eg. sandy soils/ lots of H2S = little growth
How do waves affect vegetation growth?
hihg wave activity can damage aquatic plants bubt low wave activity stimulates plant growth through cleaning of plant and increased gas exchange. Sheltered locations have more birds and thus less vegetation.
Importance of submerged plants in an aquatic ecosystem?
increase biodiversity aand biomass as they protect organisms against predators and offer a food source.
Also a habitat for zooplankton ,during the night they graze in the openwater, but in teh day they hide.
what is the relation between aquatic plants and water birds?
the birds feed on the plants so they respond to the plant population.
What are the two competition strategies?
scramble and interference competition
what is scramble competition?
using nutrients more effectively than a competitor - everyone has equal access to resources. This is seen in some algae species.
What is interference competition?
direct interference with a competitor eg. agression. This only happens with fauna such as fish chasing away other fish from their breeding grounds.
is intra or inter specific competition stronger?
intra (between congers)
Why is competition between primary producers important?
water managers often experience biggest problems with algae or other free floating plants.
predation
consumption of animals
herbivory
consumption of plants.
bottom up limitation
food availability is limiting factor
top down limitation
predation or herbivory is limiting factor.
infochemicals
chemical information agents.
Role of daphnia (water fleas)
provide competition in zooplankton community. With lots of fish you get smaller zooplankton and thus more water fleas. And you get turbid water
turbidity and fish
fish increase the turbidity of the water.
do water fleas clean the water
yes they do. For this, you need more predator fish, few juvenile fish.
biomanipulaiton
active biological management such as introducing more of a certain species to balance everything out.
trophic cascade
the relationship between different levels of the food web.
allelopathy
plants excrete infochemical s to inhibit the growth of other plants and phytoplankton.
River Continuum Concept
a description of a river, based on the idea that rivers are open systems that interact with the environment.
Upper reach order
1-3
what is the upper reach
narrow and surrounded by many plants and trees on the banks. Sunlight will not easily reach the water resulting in low photsynthesis. Amount of coarse organic matter from the vegetation is high with a very small P/R ration
dominant funcitonal group in upper reach
shredders
middle reach order
4-6
what is the middle reach
biomass production is higher than in the upper reaches as they are less narrow and sunlight reaches the water more easily. Substrates such as rocks and branches have good surfaces for algae that produce organic material. P/R ration is roughly 1
dominant funcitonal groups in middle reach
grazers and collectors, fewer shredders.
lower reach order
> 6
describe the lower reach
deep turbid waters with suspended particles that liit photosynthesis.
dominant functional group in lower reach
collectors and some predators.
fish ladders
are important around dams, they love it
self purifying capacity
organisms such as aquatic plants take nutrients and stimulate dentirification.
main difference with oceans and streams
-amount of sunlight reaching depths
- water pressure
- ocean currents
oligotrophic
water nutrients is poor
oligosprobic
water contains little organic matter
order of phytoplankton
diatoms, green algae, cyanobacteria
phytoplankton
algae that float freely in the water
what is the difference in binding capacity between P and N?
soil binding capacity is higher for P than N
Does oxygen depletion affect phytoplankton densities?
no
Which species suffer most from flushing?
slow growing algae, eg. cyanobacteria.
what is a nuisant species?
one that develops toxic floating layers.
How do aquatic plants clear the water?
damping waves, decreaseof nutrients and shading phytoplankton.
order of the trophic cascade
phytoplankton (algae) - zooplankton (eg. water fleas) - planktivorous fish - pescivorous fish
when is scramble competition applicable?
for autotrophs, as they do not actively compete for resources.
do fish increase or decrease the water quality?
decrease
is there more or less primary production in the upper reaches and explain.
there is less primary production because
