Post on 10-May-2015
description
Falling productivity as a constraint on native fish abundanceWhere have all the fish gone?
Nick Bond, Daryl Nielsen, Jim Thomson, Paul Humphries, David Crook, Jian Yen, Gavin Butler, John Koehn, David Hohnberg, Rick Stoffels, Kirk WineMiller, Paul Reich, Nicole McCasker, Mark Kennard, John Morrongiello
Historical declines
Historical declines
OverfishingDe-snaggingClearingRiver regulationInvasive species
Historical declines
OverfishingDe-snaggingClearingRiver regulationInvasive species
A bio-energetic approach
A bio-energetic approach
What is the current carrying capacity for fish?
What limits fish abundances?
a) Less primary productivityb) Altered energy pathwaysc) Non-energetic caused) A combination of these...
We consider (a) and (b) explicitlyWhat is their importance relative to (c)?
Approach
Approach
Production
Approach
Production
Food web
Approach
Production
Food web
Biomass
Approach
Production
Abundance
Food web
Biomass
Approach
Production
Food web
Biomass
Abundance
Historical Contemporary
Approach
Production
Food web
Biomass
Abundance
Historical Contemporary
Approach
Production
Food web
Biomass
Abundance
Historical Contemporary
Contemporary food web
DOC POM Non-planktonic algae Phytoplankton Macrophytes
Non-planktonic bacteria
Fungi
Mussels Decapod crustaceans
Small fish Carp
Large-bodied native fish
Planktonic bacteria
Pelagic micro-inverts
Benthic micro-inverts
Other macro-inverts
4
3
2
1
Production
ProductionAutochthonous (algae)~21 kg C / river km . Year
ProductionAutochthonous (algae)~21 kg C / river km . YearFloodplain production~30-100 kg C / river km . Day
ProductionAutochthonous (algae)~21 kg C / river km . YearFloodplain production~30-100 kg C / river km . DayPotentially big losses from altered flood regimes
ProductionAutochthonous (algae)~21 kg C / river km . YearFloodplain production~30-100 kg C / river km . DayPotentially big losses from altered flood regimes
Summary
Summary
Energy availability might explain fish declines
Summary
Energy availability might explain fish declines
Simple food web approach can quantify this
Summary
Energy availability might explain fish declines
Simple food web approach can quantify this
Synthesis of historical and contemporary data
Summary
Energy availability might explain fish declines
Simple food web approach can quantify this
Synthesis of historical and contemporary data
New perspective on restoration/recovery