Positive News For Antarctic Sea Ice

The AUV SeaBED robot under the Antarctic sea ice (Photo : WHOI).

The AUV SeaBED robot under the Antarctic sea ice (Photo : WHOI).

A new robotic study conducted by a coalition of scientist from the United Kingdom, Australia and United States has shown that the Antarctic sea ice is thicker than previously thought.

The SeaBED autonomous underwater vehicle (AUV) has allowed for more in-depth sea ice analysis than scientists have previously been able to garner from drill data measurements, ship visual measurements (that are unable to access thicker areas) and satellite images (snow cover hinders analysis of images) alone. SeaBED is able to access areas that have previously been inaccessible to researchers.

The SeaBED AUV from Woods Hole Oceanographic Institution (WHOI) is fitted with a camera that enables it to map the underside of the sea ice. Maps were made of three regions of the continent; Weddell, Bellingshausen, and the Wilkes Land. The robot covered an area of 500,000 square metres, the size of 100 football pitches.

Scientist found that the sea ice has an average thickness of between 1.4 meters and 5.5 meters, with some areas having a maximum ice thickness of 17 meters. 76 percent of the ice that was mapped was found to be deformed, this suggests that over the winter period the ice floes repeatedly collided to create a large denser body of ice (“This is in contrast to what scientists previously understood from the Arctic, where larger sections of sea ice, under constant pressure, produce longer linear ‘ridge’ features.“).

Dr. Guy Williams from Institute of Antarctic and Marine Studies adds (co-author on the paper) adds that:

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Impact of Marine Dredging on Marine Mammals – New Paper

Fascinating new paper out reviewing the likely impacts that dredging may have on marine mammals. The paper by Dr. Victoria Todd and colleagues can be read here.

It is a great review of the effects both positive and negative that dredging can have on marine life. I like that is has done this as I would have gone all BAD, BAD, BAD! However there are some positives. The paper focuses mainly on marine dredging although it is important to remember it also occurs in rivers and lakes.

Marine Dredger. Photo: United States Environmental Protection Agency (EPA) (http://water.epa.gov)

Marine Dredger. Photo: United States Environmental Protection Agency (EPA) (http://water.epa.gov)

Start with the bad…

The paper delves into the direct and indirect impacts of dredging on marine mammals and the potential severity of those.

The direct impacts are interactions that cause physical injury to mortality. These include Noise Pollution, Turbidity and Collision.

Noise pollution occurs at lots of different levels and in areas that are already heavily trafficked. Our knowledge of the hearing range of marine mammals is still limited so we can not be sure of all the effects. However it is possible that the noise emitted could cause masking of marine mammal calls particularly cetaceans. I talk about this more in this blog post. The effects are likely to be over the short to medium term and occur as behavioural changes such as area avoidance and call masking. All this will occur concurrently with other industrial activities so it is hard to tease out the specific impacts of just dredging.

In regards to collision, the slow speed of active dredgers means that there is low risk of collisions taking place especially if managed well and avoids critical habitat and calving areas. The bigger risk would be when dredging vessels are in transit but if this is occurring in an already heavily transmitted area as tends to be the case for dredging this won’t significantly add to the risk already in place.

The seabed disturbance caused by dredging leads to increased turbidity and sediment suspension. However, many marine mammals are use to turbid environments and limited vision is not an issue even for species that do not use echolocation for prey detection.

Indirectly marine mammals can be affected by changes to their environment and also to prey availability due to dredging. The paper lists the possibilities as:

  • Entrainment,
  • Habitat degradation,
  • Noise,
  • Remobilization of contaminants,
  • Sedimentation, and
  • Increases in suspended sediment concentrations.

Entrainment is the removal of species from their environment and while no data is available on this impact on marine mammals it has been noted that it can affect their prey species by removing them and their eggs along with the sediment. Therefore along as dredging is restricted during important egg and larval stages of prey species then effects are unlikely to be detrimental.

The degradation of marine habitats is something that I would be really worried about as dredgers go about their process especially since “45 case studies worldwide found that 21 023 ha of seagrass beds were lost as a result of 26 dredging projects over a 50-year period”. Sirenians (e.g. manatees and dugongs) are entirely dependent on seagrass beds while other marine mammals utilise them for prey and they are an important habitat for prey species. However, from this review I am enlightened to the fact that due to mitigation measure the impact on seagrass habitats has been reduced and that as long as mitigation is followed and planning is conducted with care the effects are minimal.

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Marine Debris Get Star Coverage At Conservation Of Migratory Species Conference And 31 Species Granted New Protection Status.

I have been following along closely these last few days on Twitter (#CMSCOP11) to the exciting goings on at the UNEP Convention on the Conservation of Migratory Species of Wild Animals (CMS).

Lots of marine related proposals and issues up for discussion including; marine debris, whale and dolphin conservation, and also 21 shark and ray species up for listing on CMS appendices (appendix I listing requires strict protection, while Appendix II requires coordinated management by the countries through which the species migrate).

The outcome of the six days of meeting was very, very positive.

All of the 21 shark and ray species up for adoption on appendices to improve there conservation protection where successfully adopted. This includes the hammerhead sharks (Sphyrna sp.) [Appendix II], manta ray (Manta birostris) [Appendix I and II], thresher sharks (Alopias sp.) [Appendix II], and silky shark (Carcharhinus falciformis) [Appendix II], this means they now require much stricter protection and coordinated management. This is brilliant as shark numbers are dwindling worldwide and many are at threat from; illegal, unreported and unregulated (IUU) fishing, overfishing, by catch, shark finning,  and habitat destruction.

scallopedhammerheadshark

Scalloped Hammerhead Shark [Photograph: Brian Skerry, National Geographic via NOAA]


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The IPCC Fifth Assessment Report is OUT!!

The Intergovernmental Panel on Climate Change (IPCC) has released its fifth assessment report on climate change.

You can read the full report here.

The report is very, very long. Even the systhesis report which is an overview of the knowledge comes in at 116 pages.

So what key points can we take away from it?

“Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.”

This is to say that YES climate change has been driven by human influence and human resource use and exploitation. There is no hiding from it (though some will hide) we are responsible for global climate change.

Anthropogenic Green House Gas Emissions since the 1970's. You can clearly see that they are increasing

Anthropogenic Greenhouse Gas Emissions since the 1970’s. You can clearly see that they are increasing and have risen more rapidly between 2000-2010 than in the previous three decades. (Graphic: IPCC).

What we know since the 1950’s is:

  • Snow and ice cover has been diminished.
  • Sea levels have risen.
  • The ocean and atmosphere are both warmer.

These are all at levels unprecedented over decades to millennia! This is not just normal fluctuations.

The Oceans have been the dominant warming environment. The largest increases have been in top 75 metres of the water column but increases have been measure at all depths including over 3000 metres (where estimates only began in 1992). In addition to this the ocean is also becoming more saline and far more acidic. In addition to the ocean warming there is also evidence that in coastal waters the oxygen concentration has decreased (warm water can hold less dissolved oxygen) as well which, is detrimental to coastal dependent species and reefs. If like me you are super interested int he ocean and the consequences for it you can browse the whole Ocean Observations Chapter.

Sea Levels have also risen in the period between 1901 and 2010. The mean rate of this sea level rise (very likely) was 1.7 [1.5 to 1.9] mm yr–1 between 1901 and 2010 and this increased to 3.2 [2.8 to 3.6] mm yr–1 between 1993 and 2010. Almost worldwide glaciers have been shrinking and the melting of sea ice has been contributing to the rise in sea levels.

What about the Atmosphere I hear you shouting…well in a very unsurprising turn of events it is also getting warmer.

“Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.”

What are the causes of all this change:

“It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together”