Viera Straskrabova

Biology Centre, Academy of Sciences of Czech Republic

Institute of Hydrobiology, Ceske Budejovice

Biodiversity in aquatic ecosystems –

related to their structure and processes

ALTERnet Summer School,Peyresc, 2006

•Spatial and organismal structure of aquatic ecosystems – main features different from terrestrial ones, types of aquatic ecosystems.

•Production processes, energy budget, turnover of nutrients and organic matter in relation to surrounding ecosystems (terrestrial ones, catchment).

•Main groups of aquatic organisms, BD problems

•Basic principles and methodological approaches for the assessment of aquatic ecosystems functions and biodiversity, both at one-ecosystem-scale and at landscape-scale.

•Goods and services of aquatic ecosystems (provisional and for human use); who are the main groups of end users? How is the biodiversity “involved” there?

•Pressures and drivers effecting aquatic BD, main threats (eutrophication, climate effect, land use, alien species)

•Spatial and organismal structure of aquatic ecosystems

•main features different from terrestrial systems

PRIMARY PRODUCERS small, fast growing, less visible

HETEROGENEITY smaller

HERBIVORES consume whole organisms

OXYGEN often less available

LIGHT often limiting

WATER everywhere round

TYPES OF AQUATIC SYSTEMS

LAKESRIVERS

TERRESTRIAL

WETLANDS

RESERVOIR

natural succession man-made

Lake Bajkal

Mountain lakes

Reservoir

•Spatial structure of aquatic ecosystems

Interphases - Ecotones

WATER -------------------------------------------------------SEDIMENT

WATER ------------------------- BIOTA ------------------ SEDIMENT

AQUATIC ----------------------------------------------- TERRESTRIAL

Hot spots of biodiversity, nutrient cycling, chemical and biochemical processes

Input of nutrients, and organicsfrom terrestrial system

River and reservoir in the catchment

Connected with ground water

Lacustrine

Riverine

•Spatial structure of aquatic ecosystems

Interphases - Ecotones

WATER -------------------------------------------------------SEDIMENT

WATER ------------------------- BIOTA ------------------ SEDIMENT

AQUATIC ----------------------------------------------- TERRESTRIAL

Hot spots of biodiversity, nutrient cycling, chemical and biochemical processes

Temperature changes in water column

0

2

4

6

8

10

12

0 10 20 30

Temperature (C)

Dep

th (

m)

25.3.

26.3.

10.4.

22.4.

23.4.

9.5.

19.5.

20.5.

4.6.

17.6.

18.6.

9.7.

Annual cycle – dimictic lake

A spring mixing

B onset of summer stratification

C maximum summer stratification

D autumnal mixing

E winter inverse stratification

•Organismal structure of aquatic systems

Everybody feeds on something (somebody)

and

Everybody (everything) is eaten by somebody

Trophic chains – food chains

Not simple – trophic (food) network

Piscivorous fish

Planktivorous fish

herbivorouszooplankton

Phytoplankton

P, N (Si) – nutrients – dissolved organic C

mixotrophicalgae and protists bacteria

protists

rotifers

predatoryzooplankton

Fish fry

Zoobentos

Phytobentos

Macrophytes

Mixotrophicphytoplankton

Bacteria

PhytoplanktonPhytoplankton

exudation

consumption

N, P recycling

exudation

N, P recycling

Heterotrophic protists

Microbial loop

Microbial loop can be consumed almost totally by filtering zooplankton

PHYTOPLANKTONPHYTOPLANKTON

PELAGIC PELAGIC BACTERIABACTERIA

Primary Primary productionproduction

Exudation

Cellular production

Death

Decay

Grazing

Excretion, excrements, sloppy feeding

SedimentSediment

•Production processes, energy budget, turnover of nutrients and organic matter in relation to surrounding ecosystems (terrestrial ones, catchment).

Aquatic systems mostly are NET HETEROTROPHIC

Respiration surpasses production

This means energy input from terrestrial systems

Especially rivers have higher allochthonous input than own production

Input of nutrients, and organicsfrom terrestrial system

River and reservoir in the catchment

Connected with ground water

Lacustrine

Riverine

Annual cycle – dimictic lake

A spring mixing

B onset of summer stratification

C maximum summer stratification

D autumnal mixing

E winter inverse stratification

•Main groups of aquatic organisms, BD problems

Main functional groups

Plankton, benthos, nekton, neuston, periphyton

Large taxonomic groups

Bacteria, cyanobacteria (blue-greens), algae, protozoans, rotifers, crustaceans, fish;

Vascular plants, mosses, snails, worms, insects and/or their larvae

Aquatic vertebrates other than fish, semi-aquatic

Piscivorous fish

Planktivorous fish

herbivorouszooplankton

Phytoplankton

P, N (Si) – nutrients – dissolved organic C

mixotrophicalgae and protists bacteria

protists

rotifers

predatoryzooplankton

Fish fry

Zoobentos

Phytobentos

Macrophytes

•Biodiversity problems

Species extinctionfish, vascular plants, (semi-)aquatic vertebrates…. Very often caused by loss or deterioration of HABITATS, which are necessary at least for one particular period of life cycles (land use changes, desertification, eutrophication, pollution) RAMSAR sites

Alien speciesvascular plants, mussels, fish …. From where??? Introduced, transported with ships, vehicles, migrating with increasing temperature…What they do??? (Nothing – or we do not know yet), compete with native species, adversely change food chains, caused nuisance, adverse health effects, obstacles for water works....

•Biodiversity problems

•Biodiversity problems

Increase in toxic or undesirable species caused by increased temperature and/or increased nutrient availability

Water blooms of phytoplankton, especially of cyanobacteria (blue-greens): allergic reactions on skin, odours in treated water, neurotoxins Microcystis

•Basic principles and methodological approaches for the assessment of aquatic ecosystems functions and biodiversity, both at one-ecosystem-scale and at landscape-scale.

Remote sensing

Modeling

System approach

Selected species groups

Continuous monitoring

Long term ecological research

Selenga

•Goods and services of aquatic ecosystems; who are the main groups of end users? How is the biodiversity “involved”there?

Water cycle in landscape – transport – connection with other ecosystems

With ground water – soil – aquifers

With the air – humidity – transport

Flood control, water storage, irrigation

Navigation, hydropower

Drinking water source

Fish production

Swimming, sport fishing, “natural beauty”

MULTIPLE USES CONFLICTING USES

Pressures and drivers effecting aquatic BD,

main threats

eutrophication

climate effect

land use changes

alien species, introduction

overexploitation

Land use changes

Deterioration or loss of habitats

Fragmentation, loss of connectideness

Desertification

Introduction and overexploitation

- changes in food webs