The Southern Ocean circling Antarctica is one of Earth’s richest marine ecosystems. Its food webs support an abundance of life, from tiny micro-organisms to seals, penguins and several species of whales. But climate change is set to disrupt this delicate balance.
Antarctic krill – finger-sized, swarming crustaceans – might be small but they underpin the Southern Ocean’s food web. Our research published today suggests climate change will cause the ocean habitat supporting krill growth to move south. The habitat will also deteriorate in summer and autumn.
The ramifications will reverberate up the food chain, with implications for other Antarctic animals. This includes humpback whales that feed on krill at the end of their annual migration to the Southern Ocean.
What we found
Antarctic krill are one of the most abundant animal species in the world. About 500 million tonnes of Antarctic krill are estimated to exist in the Southern Ocean.
Antarctic krill play a critical role in the ocean’s food webs. But their survival depends on a delicate balance of food and temperature. Scientists are concerned at how climate change may affect their population and the broader marine ecosystem.
We wanted to project how climate change will affect the Southern Ocean’s krill “growth habitat” – essentially, ocean areas where krill can thrive in high numbers.
Krill growth depends largely on ocean temperature and the abundance of its main food source, phytoplankton (microscopic single-celled plants). Under a “business as usual” climate change scenario, future changes in ocean temperature and phytoplankton varied depending on the region and season.
In the mid-low latitudes, our projections showed temperatures warmed towards the limits krill can tolerate. For example, by 2100 the waters during summer around South Georgia island warmed by 1.8?.
Warming water was often accompanied by decreases in phytoplankton; in the Bellingshausen Sea during summer a 1.7? rise halved the available phytoplankton. However, phytoplankton increased closer to the continent in spring and summer – most dramatically by 175% in the Weddell Sea in spring.
Across all seasons, krill growth habitat remained relatively stable for 85% of the Southern Ocean. But important regional changes still occurred.
Krill growth habitat shifted south as suitable ocean temperatures contracted towards the poles. Combined with changes in phytoplankton distribution, growth habitat improved in spring but deteriorated in summer and autumn.
This early end to the growth season could have profound consequences for krill populations. The krill life cycle is synchronised with the Southern Ocean’s dramatic seasonal cycles. Typically this allows krill to both maximise growth and reproduction and store reserves to survive the winter. A shift in habitat timing could create a mismatch between these two cycles.
For example, female krill need access to plentiful food during the summer in order to spawn. Since larger females produce exponentially more eggs, a decline in summer growth habitat could result in smaller females and far less spawning success.
Why this matters
Krill’s significant role in the food chain means the impacts of these changes may play out through the entire ecosystem.
If krill shift south to follow their retreating habitat, less food would be available for predators on sub-Antarctic islands such as Antarctic fur seals, penguins and albatrosses for whom krill forms a significant portion of the diet.
In the past, years of low krill densities has coincided with declines in reproductive success for these species.
Shifts in krill habitat timing may also affect migratory predators. For example, each year humpback whales migrate from the tropics to the poles to feed on the huge amount of summer krill. If the krill peak occurs earlier in the season, the whales must adapt by arriving earlier, or be left hungry.
Krill predators. a. crabeater seal (Lobodon carcinophaga), b. Adelie penguins (Pygoscelis adeliae), c. Antarctic fur seal (Arctocephalus gazella), d. humpback whale (Megaptera novaeangliae). Photo credits (in order a-d): Kevin Neff, Australian Antarctic Division; Mark Hindell, Institute for Marine and Antarctic Studies; Colin Lee Hong, Australian Antarctic Division; Anthony Hull, Australian Antarctic Division.
Changes to krill growth habitat may damage more than the ocean food web. Demand for krill oil in health supplements and aquaculture feed is on the rise, and krill are the target of the Southern Ocean’s largest fishery. Anticipating changes in krill availability is crucial to informing the fishery’s sustainable management.
Many environmental drivers interact to create good krill habitat. More research is required, including better models, and an improved understanding of what drives krill to reproduce and survive.
But by examining changes in phytoplankton, we’ve taken significant strides towards predicting climate change impacts on krill and the wider Antarctic marine ecosystem.
Devi Veytia is a PhD student and Stuart Corney is a senior lecturer at the University of Tasmania.
This article appears courtesy of The Conversation and may be found in its original form here.
Go to Source
A massive fire broke out at the Port of Beirut on Thursday, incinerating a warehouse full of tires and oil within the port’s free zone. The same area was heavily damaged in the ammonium nitrate explosion that leveled the central port area and the adjacent waterfront on August 4. According to Lebanon’s civil defense agency, […]
Over the course of the past five days, the Australian Maritime Safety Authority arranged a medical intervention for an injured aboard a freighter in the Indian Ocean. On Saturday evening, the Spliethoff tweendecker Dolfijngracht called for assistance while under way about 1,000 nauical miles off the coast of Western Australia. A crewmember had sustained serious […]
The National Transportation Safety Board (NTSB) has released a Marine Accident Brief about an accident that occurred on April 15, 2019, involving the towing vessel DeJeanne Maria which struck the end of a submerged dredge pipeline while pushing two spud barges to the Gulf of Mexico. The incident occurred on the Mississippi River in Pass […]
Best known as a leading passenger airport serving Germany’s most populated federal state North Rhine-Westphalia, Düsseldorf has become transformed into a vital distribution point, during the COVID 19 pandemic, for medical equipment and other life-saving goods, mostly from China. Gerton Hulsman, managing director of cargo operations, reports that the handling teams are working hard to […]
With close to 100 daily cargo flights operated to a destination network spanning more than 65 cities across six continents, Emirates SkyCargo is delivering essential supplies and commodities to people around the world. The air cargo carrier is currently operating 11 Boeing 777 freighter aircraft, each with a capacity to transport about 100 tonnes of […]
The UK government’s new post-Brexit tariff regime will result in both winners and losers. The new regime is set to replace the European Union’s Common External Tariff from the end of the Brexit Transition Period on December 31, 2020. The UK’s commitment to the ongoing Brexit process and ending the UK’s transition from EU membership […]
DSV Belgium has solid experience in the transport of pharmaceutical products for different customers. With a pharma hub based at Brussels Airport a lot of experience and know-how has been built up over the years. Last weekend, the forwarder handled one hundred million mouth masks, an important milestone for its Belgian organisation that has put […]
Emirates SkyCargo has expanded its weekly scheduled cargo flight operations to cover 75 destinations across six continents. Through its wider reach, Emirates SkyCargo is able to transport essential commodities and other urgently needed cargo more rapidly across the world, allowing exporters and importers across markets to benefit from direct access to widebody cargo capacity. Some […]
Global commercial aviation charter company Albion Aviation Group is reporting that it is seeing a considerable uptake in its professional cargo broker training courses from the current global pandemic crisis and surge in charter demand. “We have completed a number webinar courses for a whole of host of companies, looking to manage their own cargo […]
Operators can continue to use pilots and other crew members who have unable to comply with certain training, recent experience, testing, and checking requirements due to the COVID-19 outbreak in support of essential operations. Additionally, this Special Federal Aviation Regulation (SFAR) provides regulatory relief to certain persons and pilot schools unable to meet duration and […]
Astral Aviation has increased its intra-African network with cargo freighters during the pandemic. While there has been a reduction in capacity to, from, and within Africa, which has been caused by a stoppage of passenger flights and limited frequencies on freighter aircraft, Astral Aviation continues to operate cargo freighters from its Nairobi hub to 13 destinations […]
The U-Freight Group (UFL), with its considerable involvement in eCommerce logistics, says that the latest statistics showing that global e-commerce sales hit $25.6 trillion in 2018 are a further vindication of its decision to enter this sector of the international freight market several years ago. The latest available estimates, up 8% from 2017, were recently […]
Callan Marine is serving as the prime contractor to the Texas Department of Transportation for a maintenance dredging project located at the Bolivar Ferry Terminal, in Galveston, Texas. Work began in May and is estimated to be complete in late July 2020. The project consists of the removal of 600,000 cubic yards of material and […]
Network Airline Management and TAAG Angola Airlines are pleased to announce the renewal of their long-term freighter aircraft contract by an additional 12 months, sealing an ongoing partnership for the foreseeable future. Operating a regular weekly scheduled service from Liege, Belgium, to the capital of Angola, Luanda, Network Airline Management provides a Boeing 747-400F aircraft […]
Qatar Airways Cargo transported 56 SkyCell containers with vaccines from one of the largest vaccine manufacturers worldwide on its scheduled freighter and belly-hold cargo flights for its customer, CEVA Logistics. The 54-tonne shipment consisting of pneumococcal and varicella vaccines were flown from Brussels to Mumbai via the carrier’s hub in Doha on two separate flights. […]
NOAA Fisheries announced Friday that it will cancel five out of its six large-scale research surveys in Alaskan waters this year due to COVID-19. The canceled surveys include the Aleutian Islands bottom trawl survey, the eastern Bering Sea bottom trawl survey, the northern Bering Sea bottom trawl survey, the Bering Sea pollock acoustics survey, and […]