Life migrating through the Polar Front
Since James Cook’s second voyage in 1772-1775 to Antarctica, which saw the first descriptions of Antarctic animals, scientists have progressively revealed the composition of the Antarctic and sub-Antarctic region’s biodiversity. Since then scientist have undertaken numerous expeditions and scientific research projects to understand the unique continent’s ecosystems.
The Polar Front is permeable
One of the main areas of research is understanding the Polar Front, which is an oceanographic barrier between the Southern Ocean and its surrounding water masses. Over the past few years, scientists have discovered that it is not an impermeable biogeographical barrier was previously thought.
One of the first initial studies of the biogeography of the waters above and below the Polar Front was the development of the South Georgia Marine Biodiversity Database (SGMarBase). This database was created as a repository to establish a baseline on the various macro- and mega-benthic biodiversity of the South Georgia shelf and slope, enabling scientists to identify key species and biodiversity hotspots: the archipelago of South Georgia is one of the largest, most isolated land masses in the Southern Ocean.
The combinations of having separated early from a continental land mass, a large shelf area, geographical isolation and its proximity to nutrient rich currents means the area is biologically rich and distinct. The database was also the first attempt to map the biogeography of an archipelago south of the Polar Front with biological data incorporated with physical data including seabed topography and physical oceanography.
Prior to the creation of this database, scientists from various projects had collected a large amount of biodiversity data from the area but the majority of it was scattered across numerous literary sources, stored by various institutes as well as being in different languages. The data was also not logged with georeferences.
By collating all this data, checking and standardising it into one repository it means that scientists now have access to one central database holding nearly 25,000 records and identifying over 1,400 species from the South Georgian shelf including sea urchins, free-swimming words, fish, sea spiders and crustaceans. This database shows that South Georgia supports more species that Galapagos and Ecuador combined and during the breeding season hosts the densest mass of marine mammals on Earth.
The Polar Front’s biodiversity
In a more recent study, scientists have discovered that the Polar Front may be even more richer than previously believed with a new study showing the most complete inventory so far on the distribution of bryozoans, which are marine invertebrates that live in colonies and form mineralised skeletons in the shallow waters of the Falkland Islands and the South Georgia Islands.
In the study, a group of scientists from a variety of institutions, including the Biodiversity Research Institute of the University of Barcelona, British Antarctic Survey and the South Atlantic Environmental Research Institute, identified 85 different species, among which are 18 types and 23 species could be unknown. From all the identified species, 65 percent were named for the first time in the Falkland Islands. According to one scientist, the new inventory for bryozoans will enable the creation of a database of regional bryozoan diversity and allow researchers to detect possible invasive species.
Overall, the study, which spreads the bathymetric study range into 30 marine species, analysed the fauna similarities among the communities of bryozoans in neighbouring areas and will serve to design biogeographical distribution patterns. The scientists now state that the Polar Front is not impermeable as once thought as they have found evidence of species spreading across the Patagonian region to Antarctica.
How did life spread throughout the Antarctic region?
Scientists from Monash University in Australia are leading a terrestrial component of a major new expedition to better understand Antarctic ecosystems. Using new genetic and computational approaches, the team will seek answers to an unresolved question: how has life evolved and spread around the Antarctic region both in the past and today?
The project, named A Functional Biogeography of the Antarctic (AFBA) forms part of the wider Antarctic Circumnavigation Expedition (ACE). ACE involves 22 projects, 55 researchers and 19 countries and is manged by the Swiss Polar Institute. As part of the Monash University project, scientists from all around the world, including France, Germany, New Zealand, Russia, South Africa, United Kingdom and the United States, will visit sites across the sub-Antarctic and Antarctica to uncover new species of animals and plants, which in turn will guide new ways to help conserve biodiversity in the Antarctic regions.
Specifically, AFBA will provide a comprehensive biodiversity assessment of the region’s terrestrial and intertidal plants and animals. Based on the assessment of these species with advance genetic and computing techniques the researchers will be able to create a biological history of the region which shows where different groups have their origins, how different species across the islands are related and connected and how life on these islands are related to that of other southern continents.
The researchers will also attempt to understand how frequently different groups have moved between Antarctica and the sub-Antarctic islands, when this happened and the extent to which it continues today. By genetically testing species found it will provide insights into the adaptations that have enable life to flourish in the Antarctic region. Regarding future protection of the continent, the scientists aim to provide a baseline biodiversity surveillance system for the region to help conservation managers identify the species to which newly arrived individuals belong to and whether they pose a threat.
The overall aim of AFBA is to leave a legacy for future scientists in a number of areas including:
- Resolution of fundamental questions about how has life evolved in the Antarctica
- Discovery of species new to science
- Improved understanding of the region to the benefit of conservation management
- Publicly accessible information to improve knowledge and appreciation of Antarctica’s wilderness, conservation significance and sheer beauty
- Education and inspiration of a new cohort of polar scientists and enthusiasts
Finding the connection between life on land and water
In addition to understanding biodiversity in the waters around the continent, scientists are also trying to understand the link between biodiversity on land and water. For instance, in the Falkland Islands, scientists are learning about its biodiversity and what can be done to preserve it for generations to come. In one study, researchers from the University of Maine studied the island’s environmental history throughout the last 20,000 years to establish a baseline for conservation efforts as the island is home to some of the most important penguin rookeries populations in the world, with a large number of other species not found anywhere else. One of the areas the scientists studied was how to protect the penguin-tussock grass relationship as the native grass provides habitat for penguins and other sea birds and marine mammals and relies on nutrients provided from the animals’ waste. The researchers took sediment core samples from several locations.
By analysing the pollen and seabird guano, or waste, within the cores, they could analyse over time how penguin and tussock grass populations have fluctuated through time, under different climatic conditions. This is part of understanding the wider marine-terrestrial link which is the connection of nutrients originating in the marine ecosystem that is transferred to the terrestrial ecosystem. In the Falklands region, the soil is very nutrient poor, making nutrients coming from the marine ecosystem very important.
