A melting world? Indirect impacts of sea ice loss

With the last post concentrated on the direct effects of sea ice loss in the Arctic, this post will look again at tithe phenomena of sea ice, but with a particular focus on the indirect impacts of Arctic sea ice disappearance. Below is a short video which aims to portray ice minimum volume from 1979 to 2013.

Sea ice loss may influence ecological dynamics indirectly through effects on species movements and disease transmission causing species to become more vulnerable. Arctic populations isolated when an ice free season occurs in the Arctic, the declining presence of sea ice could reduce inter-island migration. With the lengthening of the ice free season, genetic isolation among populations is encouraged (Post et al. 2013). For some species, sea ice can act as a barrier to dispersal, due to the lengthening of the sea ice free season will increase population mixing, reducing genetic differentiation. This impending loss of sea ice will increase contact among closely related series for which it currently acts as a mixing barrier. Hybridisation is likely to become increasingly common. Polar bears and grizzly bears may be the result of increasing inland presence of polar bears as a result of prolonged ice free seasons (Hoflinger, 2013).  In Canada, the projected decrease in sea ice cover with Arctic warming, will increase contact between Eastern and Western Arctic species.

Image of a 'pizzly' the grizzly-polar bear hybrid. 

A second indirect impact is changes that occur in animal behaviour as a result of sea ice loss. In the Canadian Arctic, later ice seasons and increased shipping traffic due to the lengthened ice free seasons could prevent migration of the Dolphin and Caribou (Poole et al. 2010). It is widely understood by ecologists that migration can decrease the likelihood of parasitism. The changes in ice formation within the Arctic could change the amount of parasite loads among the Dolphin migration herds. However, sea ice loss is not always looked on negatively, with the reduction of sea ice promotion migration hence preventing disease epidemics where the sea ice provides a corridor for pathogen transmission (Post et al. 2013).

Image. Caribou migration route in the Arctic. 

Sea ice loss also effects terrestrial ecosystems including especially, land adjacent to the sea ice. Arctic warming, delayed freeze season and sea ice loss will promote permafrost warming increasing terrestrial primary productivity. There has been increases in the abundance and cover of shrubs occurring across the Arctic. 

A recent report by the Arctic council and the National Oceanic and Atmospheric administration (2013) shows evidence of a shift to a new warmer, greener state. The major findings of this report include:

1) Vegetation in the Arctic is greener with a longer growing season. 

2) Wildlife and large land mammal populations continued declining trends with Caribou having unusually low numbers. 

3) Sea ice extent in September 2013 was the sixth lowest since observations began in 1979. 

4) Northward migration into the Arctic of fish such as Atlantic Mackerel and Atlantic Cod. 

This report shows that recently there has been increased concerns over this region of sea ice loss. With the academic community trying to understand how extensive the impacts of sea ice loss are. With conditions changing for many species in the Arctic, it is important to note that sea ice decline is not itself solely responsible for many individual species decline, however it plays a role with a combination of other factors. Declining sea ice is not uniform and therefore individual species responses will remain varied (Mueter and Litzow, 2007).

As we can see from the last two posts, sea ice loss can have both negative and positive effects on the ecological diversity of the Arctic. Keep your eyes peeled for the next post which will offer some insight into a completely different area of global biodiversity, one that is extremely threatened- freshwater biodiversity.


Score Board Update.

Anthropocene 4 - 3 Biodiversity 

Oceans- What will the future hold?

In previous posts I have concentrated on mainly terrestrial biodiversity (however not on purpose). Today I take a swim with the fishes to investigate one of Earth's most interesting biomes- the ocean.

'The ocean covers nearly three quarters of the Earth's surface, provides about half of the oxygen we breathe and feeds billions of people every year' (Le Roux, 2013). 

The oceans have been protecting the Earth from the worst effects of human induced climate change for years by absorbing excess carbon dioxide (Bijma et al. 2013). This absorption, however, is having a negative effect driving the oceans into an acidic state. Along side this acidification, ocean warming is having grave impacts on the structure of many marine ecosystems. Bijma et al.(2013) coined ocean warming, acidification and deoxygenation the 'deadly trio' of anthropogenic impacts that are causing  accelerated loss of marine populations (Worm et al. 2006). Since the industrial revolution the world's oceans have become 26% more acidic and will continue to force oceans into a acidified state at an unprecedented rate.

Ocean acidification is the reduction in the pH of the ocean waters by the uptake of carbon dioxide from the Earth's atmosphere. It can also be caused by chemical pollution into the oceans. The carbon dioxide dissolves in the seawater generating changes in seawater chemistry. The addition of carbon dioxide increases the concentration of bicarbonate ions and carbonate ions which, consequently lowers the pH making oceans more acidic. For a beginners insight into ocean acidification take a look at the below flow chart, showing the changes in chemistry from slight alkaline to acidified seawater. 

Beginners guide to ocean acidification.

Many recent reports, have discussed how ocean change may be faster than any time in the last 300 million years, predicting that by 2100 there will have been a 170% increase in ocean acidity. But is it all doom and gloom for oceans? There has in fact,  been scientists that have discussed how marine species could survive and even thrive (seagrass) under ocean acidification and warming (McGrath, 2013). 

What environmental scientists are most worried about is the effect of the 'deadly trio' on corals. In the Great Barrier Reef half of the coral cover has been lost over the past 27 years. There have also been dramatic coral bleaching events in 1998 and 2002 due to anthropogenic ocean warming. In the Southern Ocean, we can unfortunately already see corrosion of pteropods (sea snails) shells. In my next post, I aim to expand on corals in more detail, focusing on the threats posed by the anthropocene to these highly sensitive environments. 

Coral Disaster: Great Barrier Reef coral bleaching. Source. 

With a carbon release of around 30 gigatonnes of carbon dioxide a year, it is no surprise that academics are worried about a major ocean extinction. As I touched upon in my previous post a sixth mass extinction' is a upcoming worry. However, speculative this theory may be, oceans are one of the biomes which are most vulnerable to a huge biodiversity decline. With changing ocean conditions, many species could possibly find themselves in unsuitable environments, especially in oxygen poor "dead zones"(Le Roux, 2013). 

What will the future hold for the oceans? Will there be a biodiversity loss in one of the worlds most diverse environments? Keep your eyes peeled for my next post which will look at the threats posed to corals.

Score Board Update. 

Anthropocene 2- 1 Biodiversity.