Good Paper on General Effects of Climate Change on fish populations:
is attched.
Possible Historical Effects of Global warming:
- Change in average water temperature
- Changes in Surface currents
- Changes in deep water thermo-haline currents
- Formation of anoxic regions
- Intensified atmospheric pressure gradients => Increased storm frequency, increased upwelling?, increased advection?
- Increased C02 => increased pH
- (relatively) sudden climatic change events - due to change in currents
- Sea level rise => Change in vertical distribution
- Oceanic methane and hydrogen sulfide eruptions might increase
Geological record of mid-Cretaceous shows Carbon-rich (Black) Shales, indicating the prescence of extensive or global anoxic water masses. This corresponds with rapid global warming events and CO2 outgassing. Also around this time the source of deep water currents abrubptly shifted latitudes, which is believed to be at least partially responsible for the extinction of certain types of bivalves. Similar events are believed to have occurred at the Eocene-Oligocene boundary (a result of CH4 outgassing).
-New evidence for abrupt climate change in Cretaceous
Used modeling to look at triggers and feedback mechanisms. Once global warming has been initiated, it is likely to be worsened by positive feedback, such as by perturbation of marine hydrates. This means that in a warm world, even moderate changes in CO2 and CH4 concentrations can cause warming periods. This can also result in large regional climatic changes
Stronger wind fields might lead to enhanced upwelling in eastern boundary currents (Bakun 1990), which could increase nutrient availability at the surface.However, stronger thermal stratification and a deepening of the thermocline could prevent cool, nutrient-rich waters from being upwelled.
Harley, Christopher D. G. et. all. The impacts of climate change in coastal marine
Systems. Ecology Letters, (2006) 9: 228-241
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Northern-Eastern Pacific Region:
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-Peterson B
(4) The state of the California current, 2005-2006: Warm in the North, cool in the South
Paleoclimatic data suggest that upwelling in the California current system is positively correlated with temperature over millennial timescales (Pisias et al. 2001). Furthermore, upwelling along the California coast has increased over the past 30 years, and these increases are expected to continue. It is also fairly certain that advection should increase in the California current. The upwelling could have a beneficial effect on the ecosystem if it is not too strong, but advection would likely have an adverse effect. Modelling work suggests that increased offshore advection is often negatively correlated with adult population size, and very strong upwelling could theoretically prevent a species from maintaining an adult benthic population at particular sites.
Therefore, it is most likely that the populations of fish in this region will be negatively affected by climate change. This would have to be taken into account and stricter enforcements would be needed to produce the same results that would be expected without climate change. However, if the benefits of the upwelling are seen to be outweighing the harm done, these restrictions could probably be relaxed.
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Southern-Eastern Pacific Region:
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-3) Qiong Zhang - Haijun Yang - Yafang Zhong -Dongxiao Wang
An idealized study of the impact of extratropical climate change on El Nin˜ o-Southern Oscillation
It is likely that El nino events will increase with either frequency or intensity, even if the climate stays relatively normal in other years.
Harley, Christopher D. G. et. all. The impacts of climate change in coastal marine
Systems. Ecology Letters, (2006) 9: 228-241
If the first case occurs and the system shifts in the El Nino spectrum, then the fish populations in this region stand to be much lower than would be expected otherwise. This would have to be taken into account and stricter enforcements would be needed to produce the same results that would be expected without climate change. The fisheries in these regions might also take additiional hits during el-nino years, so aditional protection might be required for these years.
If the second case happens, then climate will probably play a much smaller role, and plans can be carried out without too much modification for climate change.