Biodiversity in aquatic ecosystems related to their structure and processes

Transcription

1 Biodiversity in aquatic ecosystems related to their structure and processes Viera Straskrabova Biology Centre, Academy of Sciences of Czech Republic Institute of Hydrobiology, Ceske Budejovice ALTERnet Summer School,Peyresc, 2006

2 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)

3 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

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6 TYPES OF AQUATIC SYSTEMS LAKES RIVERS RESERVOIR natural succession man-made WETLANDS TERRESTRIAL

7 Lake Bajkal Mountain lakes Reservoir

8 Spatial structure of aquatic ecosystems Interphases - Ecotones WATER SEDIMENT WATER BIOTA SEDIMENT AQUATIC TERRESTRIAL Hot spots of biodiversity, nutrient cycling, chemical and biochemical processes

9 River and reservoir in the catchment Input of nutrients, and organics from terrestrial system Connected with ground water Riverine Lacustrine

10 Spatial structure of aquatic ecosystems Interphases - Ecotones WATER SEDIMENT WATER BIOTA SEDIMENT AQUATIC TERRESTRIAL Hot spots of biodiversity, nutrient cycling, chemical and biochemical processes

11 Temperature changes in water column

12 Temperature (C) Depth (m)

13 Annual cycle dimictic lake A spring mixing B onset of summer stratification C maximum summer stratification D autumnal mixing E winter inverse stratification

14 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

15 Piscivorous fish Planktivorous fish Fish fry Zoobentos herbivorous zooplankton predatory zooplankton rotifers protists Phytobentos Macrophytes Phytoplankton mixotrophic algae and protists bacteria P, N (Si) nutrients dissolved organic C

16 Phytoplankton Microbial loop exudation N, P recycling exudation consumption N, P recycling Mixotrophic phytoplankton Heterotrophic protists Bacteria Microbial loop can be consumed almost totally by filtering zooplankton

17 PHYTOPLANKTON Primary production Cellular production Death Grazing Exudation Excretion, excrements, sloppy feeding Decay Sediment PELAGIC BACTERIA

18 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

19 River and reservoir in the catchment Input of nutrients, and organics from terrestrial system Connected with ground water Riverine Lacustrine

20 Annual cycle dimictic lake A spring mixing B onset of summer stratification C maximum summer stratification D autumnal mixing E winter inverse stratification

21 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

22 Piscivorous fish Planktivorous fish Fish fry Zoobentos herbivorous zooplankton predatory zooplankton rotifers protists Phytobentos Macrophytes Phytoplankton mixotrophic algae and protists bacteria P, N (Si) nutrients dissolved organic C

23 Biodiversity problems Species extinction fish, 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

24 Biodiversity problems Alien species vascular 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...

25 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

26 Basic principles and methodological approaches for the assessment of aquatic ecosystems functions and biodiversity, both at one-ecosystemscale and at landscape-scale. Remote sensing Modeling System approach Selected species groups Continuous monitoring Long term ecological research

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28 Selenga

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30 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

31 Pressures and drivers effecting aquatic BD, main threats eutrophication climate effect land use changes alien species, introduction overexploitation

32 Land use changes Deterioration or loss of habitats Fragmentation, loss of connectideness Desertification Introduction and overexploitation - changes in food webs

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