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Climate clarification Albedo Definition: the extent to which an object reflects light from the sun Range of values: 0 to 1 Impact: high albedo, high reflectance less solar energy absorbed by object. Typical albedo Snow 0.8-0.9 Tundra shrubs 0.2 summer 0.6 snow covered

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Climate clarification

Albedo

Definition: the extent to which an object reflects light from the sun

Range of values: 0 to 1

Impact: high albedo, high reflectance

less solar energy absorbed by object


Typical albedo

Snow 0.8-0.9

Tundra shrubs 0.2 summer

0.6 snow covered

Amazon forest 0.13

Amazon ranchland 0.18

Boreal forest 0.08

Boreal grass 0.2


Feedback loops

Warming will melt sea ice and promote growth of shrubs in the arctic

Puddles and shrubs have lower albedo (reflectance) than ice and tundra

Puddles and shrubs will warm up rather than reflect solar energy

Warm puddles and shrubs will increase ice melt and promote further shrubification


Feedback effects on climate

  • Impact of Deforestation

  • Ranchland has higher albedo

  • 0.18 vs 0.13

  • Surface absorbs less energy

  • Cooling effect

  • Ranchland has much less evaporation

  • Warming effect

  • Net effect

  • WARMING

+- indicates effect of forest

on temperature


Feedback effects on climate

  • Impact of Deforestation

  • Grassland has higher albedo

  • 0.20 vs 0.08

  • Surface absorbs less energy

  • Cooling effect

  • Grassland has slightly less evaporation

  • Warming effect

  • Net effect

  • ?????

+- indicates effect of forest

on temperature


Humans fisheries and tough conservation decisions

Humans, fisheries and tough conservation decisions

A Case study:

Lake Victoria’s Nile perch fishery and cichlid biodiversity


Lake victoria
Lake Victoria

  • Largest lake in Africa (68,800 km2), seventh in the world by volume.

  • Tanzania, Uganda and Kenya all share the lake and its resources, but regulations governing resources are different in each country.

  • Annual catch: 400-500,000 tons bringing in US$250,000-500,000.

  • 2 million people depend directly or indirectly on fishing activities.


European History

1858 “discovered” by John Speke

- sparsely populated region

- subsistence fishery (small native species)

1902 – colonial government links lake to Mombasa

1930 – Europeans had deforested watershed

- planted tea coffee sugar tobacco cotton

- population had exploded

- urban centres provided market for fish

1950 – native tilapia commercially extinct

1951 - English introduce non-native tilapia

1955 – English introduce Nile Perch


Fishing history – the early days

Ngege

Catfish

Haplochromines


Impacts of Nile perch

1955 – introduced to Lake Victoria

1969-70 Haplochromines 83% biomass

Nile perch 0.05%

1980’s Nile Perch 80% biomass

Haplochromines <1%

Massive loss diversity

400+  200 species


Fishing history

– the next 30 years

Decline has continued


Lake victoria summary so far
Lake Victoria – summary so far

  • The local multi-species fishery is now dominated by 3 species and supplies an international market

  • 200 endemic Cichlid species were driven to extinction in 30 years

  • Overfishing, industrial and agricultural pollution, an increasing human population and noxious water weeds, all threaten the sustainability of Lake Victoria.

  • The Nile Perch is being overfished.


What happened next?

Intensive fishing led to a resurgence of native species

Haplochromine cichlids, particularly pelagic species recovered

Three areas acted as refugia

- Wetlands and rocky habitats

- Hypoxic areas

- Satellite lakes


The future?

But current environment is very different

New fauna will differ in richness,

composition and ecosystem function


The sociopolitical context

Award winning documentary by

Hubert Sauper is a tale about

Lake Victoria, humans in the north and south, globalization,

corporate corruptness, and fish.

The following are excerpts

from the film.


If goal is to conserve the remaining cichlid diversity what should conservation biologists do?

Options?


The roundtable
‘The Roundtable’ should conservation biologists do?

The Lake Victoria Fisheries Research project has organised fisheries managers to work on quantifying the fisheries stocks of Lake Victoria and has also managed to bring together scientists from the 3 countries to exchange views and identify gaps in research and recommend how to deal with those gaps.

Planning for the lake’s future (economically and biologically) may proceed with a two-pronged approach:

  • Managing the fisheries to maintain the greatly increased yields and;

    • “The fisheries managers”

  • Conservation of the remaining indigenous species.

    • “The conservation biologists”


Lake Victoria Fisheries Organization (LVFO) comprises stakeholders whose objective is to

“protect and restore the lake”.

Where is the political power?

Whose interests are being protected?

Given the population pressure and the industry/political pressure

what would YOUR conservation strategy be?


Possible avenues for biodiversity conservation stakeholders whose objective is to

Conservation of habitat and biodiversity will only succeed if water quality is improved –

nutrient levels and toxic contamination should be controlled

Stock management strategies linked to rational regulation of fishing effort are needed

Representative habitats in the lake should be conserved with focus on high diversity areas, refugia, satellite lakes and shoreline wetlands

Development of an integrated basin wide plan

- international cooperation is necessary to regulate nutrient influx and fishing pressure


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