Climate change consequences

The latest papers I've been looking at have a common theme between them. They both discuss different ecological theories that they have found do not apply to marine ecosystems. 

Firstly Blanchard et al.'s paper looks at how climate change will affect primary production and fish production in oceans, and specifically, on shelf-sea ecosystems (areas of ocean adjacent to land, where the ocean covers continental shelf). Despite the fact that the majority of fish caught are from shelf-sea ecosystems, there were previously no models that took into account the specific conditions in these areas such as tide, wind, run off, etc. Blanchard et al decided that this had to change, and in order to do it, had to come up with a new way of predicting the effect of climate change on biomass and production in marine communities. Whereas previously this was done through species, in their study, they used a size based model which did not use species data, but simply how big the fish were. This then corresponds directly to food webs, since in the ocean, the size of consumers tends to relate to their position in the food web. For example, primary producers tend to be microscopic, and are at the bottom on the food web.

The outcome of the paper was that in tropical shelf and upwelling areas, such as the eastern Indo-Pacific, the

northern Humboldt and the North Canary Current, declines of 30-60% of potential fish production were predicted, whereas in high latitude sea shelf areas, the production of pelagic predators was expected to increase by 28-29%.

What this new technique found was that on a global scale, referring to fish by size is very useful for simplifying models. However, on local scales, switches in species were not monitored, and energy inputs other than phytoplankton were not considered (such as algae and mangroves).

The second paper tests the ecological theory that small species are less vulnerable to extinction because their populations are more able to recover, on fish.  It compared the body size of fish with their level of global threat. In marine fish, it was found that when fishing was a major risk, there was a greater frequency of large bodied species at risk, which fits with the ecological theory. However, in the ocean, the wide range of risks mean that this doesn't always fit. Some species of small fish were found to be at greater risk of extinction than large fish when threatened with habitat loss. Cast your mind back to my blog on coral reefs; its those same small species that are referred to in this paper. They are especially at risk because they have small populations to start with, and a highly specialised habitat that only exists over a small area.

So, more fishy things to think about. Just remember that principles that apply on land don't always apply in the ocean. The fact that we're still discovering this, yet again shows just how little we know about our oceans and the creatures within.