33: Freshwater ecosystems (rivers)

rivers make up ___% of the worlds water volume

0.00009

3 multiple choice options

rivers are home to __% of the world's fish species

40

3 multiple choice options

rivers link ground water and lakes by ________ to the sea

estuaries

3 multiple choice options

river continuum concept

model that predicts changes in biological communities with stream order and channel size

(size, substrate, abiotic factors, biota)

flow speed (river continuum concept)

head waters are fast and narrow

lower reaches are slow and large

1 multiple choice option

light penetration (river continuum concept)

headwaters are overshadowed by trees

mid reaches have unobstructed sunlight

lower reaches have high turbulence reducing visibility

2 multiple choice options

temperature fluctuation (river continuum concept)

head waters have low temperatures due to higher latitude and canopy shading

mid reaches have shallow depth and open canopy

low reaches have high water volume and low temperatures

2 multiple choice options

head waters

high up

nutrients (river continuum concept)

nutrient poor head waters

river accumulates nutrients mid way

nutrient rich low reaches

1 multiple choice option

natural sources of river nutrients

detritus (leaves, sticks)

phosphorus (rock erosion)

nitrogen (atmospheric deposition)

anthropogenic nutrient sources for rivers

phosphorus: manure, fertiliser, sewage

nitrogen: acid rain, fertilisers, sewage, manure

biodiversity is highest in ________ of rivers

middle reaches

2 multiple choice options

river continuum concept numbers

headwater: 1-3

mid reaches: 4-6

large rivers: 6+

2 multiple choice options

river shredder

large organic material (leaves and wood)

river collectors

small dead organic material

river grazers

scraping algae or filtering

threats to river systems

- dams block migration routes and disrupt habitat

- overexploitation of fish

- global warming

- eutrophication from agricultural and urban areas

- water withdrawal for human use

- invasion of exotic species can harm native animals and plants

_______ waterbodies are at risk of not meeting their environmental objectives

1460

In 1980, Ireland had ___ pristine river sites. Now only ___!

500, 21

River quality is

declining

rivers are at risk mostly due to

agriculture

what aquatic habitat is most at risk?

rivers

what is mostly driving increased river pollution?

agricultural intensification

river stressors caused by farming

- dissolved nutrients increase

- deposition of fine sediment increases

- water temperature increases

- water input decreases

- chemical pollutants increase

1 multiple choice option

antagonistic stressor effect

stressors interact and the effect is smaller than expected on the basis of individual stressors

1 multiple choice option

synergistic stressor effect

stressors interact and the effect is larger than expected on the basis of individual stressors

1 multiple choice option

additive stress

simple - effect of all stressors combined is equal to the sum of the individual stressors

complex stressor interactions

stressors interact in a complex way

fine sediment is ____ influential than nutrients

more

fine sediment is ___ on its own but makes other stressors _____

detrimental, worse

2 multiple choice options

zebra mussel

invasive species in Caspian and Black Sea, spread by boat movements, filter feeder - extinction of native mussels

common dace

invasive species in irish sea

round goby

invasive species in great lakes

what determines the success of invasive parasites?

life cycle, specificity