More Consequences of Warming Oceans

[gleem]

Science has known of the sensitivity of organisms to temperature. Recently algal blooms have occurred in arctic waters. A particular one is of concern Alexandrium catenella in the Bering Sea. These algae produce a toxin that shellfish consume that can paralyze shellfish humans who consume them. Some areas had concentrations 100 times higher than is needed to produce a health warning.
https://www.science.org/content/article/warming-oceans-are-pushing-harmful-algal-blooms-polar-waters#:~:text=Fachon and colleagues suspect the,allowed the algae to expand.

Also, the warming waters have affected the red king crab harvests. Fishermen have just started harvesting last fall again after a two-year moratorium.

As the clock ticks, we see the slow continuing changing of the dynamics of our ecosystems.

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[gleem]

I edited by OP because I misread the effects of the toxin. The shellfish consuming the algae accumulates the toxin. If these shellfish are consumed this can lead to paralytic shellfish poisoning that can be fatal.

These blooms ( also known as Red Tides) have occurred around the US for many years usually in summer as the waters warm. The algae reproduce by producing "cysts" that accumulate at the bottom of the water and are activated by the warming winter waters. In the Gulf of Maine for example theAlexandrium catanella and Alexandrium fundyense are common and the water temperature in the winter is less than 50 deg F. As the water warms above this temperature in the spring and summer the cysts float to the surface producing the blooms. There have been many red tide health warnings on the east coast when levels of the toxins could be fatal. As noted in the article in the OP the Bering Sear blooms had regions where the concentration of the toxin was 100 time higher that the warning threshold.

 

[Laroxe]

I do wonder about the effects of temperature, which has always been highly variable across the worlds oceans. While sunlight and temperature support the growth the other and perhaps more significant change is in the availability of nutrients. The problems associated with algae growth in freshwater, primarily cause by the overuse of fertilizers has been recognized for years, prompting some rather ineffective attempts to reduce this form of pollution. These more frequent blooms in the sea, in algae species that have always been present suggest that one of the factors controlling the populations has been removed, generally the open oceans have always been considered to have a very limited capacity to support life. These blooms appear more likely close to land areas with significant human populations. Algaes are one of the basic food sources for a wide range of marine life but these blooms reflect a basic disturbance in the usual balances that control the populations.

 

[BillTre]

Increased water temperatures reduce the water's capacity to dissolve oxygen. This may be a problem of the planktonic predators are more susceptible that the algae.

Productive areas of the ocean are often based on algae which are eaten by larger things and eventually fish. The algae growth is often based on up-welling nutrients from deep water which is driven by ocvean currents.

The gulf coast of Florida has been having a lot of algae blooms. The Gulf of Mexico's temperature has been increasing there are also nutrient runoff problems from the land. I don't know if those are causing it or something else.

An additional problem which may eventually effect Europe and the UK is the gulf stream which brings warm water from the gulf toward Europe. This may happen due to freshwater from melting sea ice and glaciers ref). It is feared that the current will eventually collapse. This is expected to have big effects on Europe's climate.

 

[Laroxe]

This has been a significant problem in a wide range of water environments including marine, fresh water, standing water flowing water etc and there are a range of algae species involved. While the growth will inevitably involve the availability of light and the optimum temperatures the fact that 71% of the earths surface is covered in water does suggest that there will always be somewhere that provide optimum conditions. Certainly, most water management agencies have identified the availability of nutrients, as the change driving the increasing occurrence and been attempting to manage this form of pollution for several decades I suspect as oxygen is dissolved at the surface, it may play a part in preventing planktonic predators but the blooms effect on the surface layer may be more significant. Though to be honest I think the algae's rate of reproduction is more likely to simply overwhelm and control by predation. The effects of the bloom on the water quality and the fact that some algae can be toxic could then slow any effective increases in predation.
I admit that I get concerned about the tendency to attribute everything to global warming, it tends to shift the focus, and control attempts, away from any other environmental concerns. There are a wide range of environmental issues that are now linked to global warming despite of rather than because of good evidence of a link. There is sufficient evidence that warming may be a serious cause for concern but the range of claims have damaged the credibility of this evidence. Then we are faced with the actions of various individuals and groups that are increasingly damaging public support for action, its all rather sad really.

The link is to a water management site based in Florida.

https://www.sjrwmd.com/education/algae/