Антарктидын Фильхнерийн мөсөн голын доор 60 сая орчим загасны үүр бүхий дэлхийн хамгийн том үржлийн бүсүүдийн нэг оршин тогтнож байгааг судалгаагаар баталлаа.
Альфред Вегенер Институтийн (AWI) бүтээсэн LASSIE хэмээх бие даасан шумбагч төхөөрөмж нь 48 цагийн турш тасралтгүй хяналт хийж, 2022 онд анх тогтоогдсон загасны үүрүүдийн нягтрал өөрчлөгдөөгүй болохыг нотолжээ. Судалгаагаар дөрвөн метр квадрат талбайд нэг үүр оногдож байгаа бөгөөд нийт 240 хавтгай дөрвөлжин километр талбайг хамарсан энэхүү колонийн нийт биомасс 60,000 тонн гэж тооцоологдсон байна. LASSIE төхөөрөмж нь өндөр нарийвчлалтай камер, лазер сканнер болон дууны долгионы сонар ашиглан 75 сантиметр диаметртэй, дунджаар 1,700 өндөг агуулсан үүрүүдийн бүтцийг нарийвчлан зураглажээ.
Судлаачид загаснууд өндгөө хэвийн бойжуулахын тулд гүний усны урсгалаар дамжин ирдэг, орчны уснаас 2 хэмээр дулаан 0-ээс 0.5 хэм хүртэлх температуртай усны бүсийг сонгон үүрээ засдаг болохыг тогтоов. Гемоглобин болон улаан эсгүй өвөрмөц бүтэцтэй Жонагийн мөсөн загаснууд (Neopagetopsis ionah) өндгөө хамгаалахын тулд ийнхүү үүр засдаг бөгөөд эр загаснууд үүрний 85 хувийг нь махчин амьтдаас хамгаалан манаж буй нь ажиглагджээ. Үүрний доторх лаг шаврын түвшин орчныхоосоо 40 хувиар бага байгаа нь загаснууд үүрээ байнга цэвэрлэж арчилдаг болохыг илтгэж байна.
Энэхүү колони нь Ведделийн далайн экосистемд чухал үүрэг гүйцэтгэдэг бөгөөд Ведделийн далайн хавнууд үржлийн оргил үед тус бүсэд идэвхтэй ан хийдэг нь акустик болон хиймэл дагуулын хяналтаар батлагдсан. Бүс нутгийн биологийн олон янз байдал болон экосистемийн эмзэг байдлыг харгалзан, далайн ёроолын загас агнуур болон уур амьсгалын өөрчлөлтөөс хамгаалах зорилгоор энэ газрыг Далайн хамгаалалттай бүс (MPA) болгох саналыг Антарктидын далайн амьд нөөцийг хамгаалах комисст (CCAMLR) хүргүүлээд байна.
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An autonomous underwater vehicle named LASSIE has spent 48 hours continuously monitoring the seafloor beneath Antarctica’s Filchner Ice Shelf, confirming that a colony of an estimated 60 million active nests remains in place in the Weddell Sea. The survey was carried out by the Alfred Wegener Institute (AWI), whose new vehicle (its name stands for Low-Altitude Survey System for Icefish) was sent to check on what is recognized as one of the largest known fish breeding colonies on Earth.
Researchers first mapped the colony in 2022, when they recorded nests spread across 240 square kilometers of seabed. Data gathered during the recent Antarctic spring season show that nesting density has held steady since that original count, at roughly one nest per four square meters across the surveyed transects. The AWI team completed its first continuous 48-hour monitoring cycle at the site before reporting the results.
That consistency matters because it tells researchers the colony has not thinned out or shifted position in the years since it was first documented. The survey also recorded seabed temperatures that were 2°C warmer than the surrounding bottom water, a difference that is small in absolute terms but significant in Antarctic conditions. The thermal anomaly, linked to upwelling deep water, maintains the narrow temperature range that the nesting fish need for their eggs to develop successfully.
Confirming the Scale of the Colony
LASSIE overcame limits in visual coverage that had affected earlier surveys by using a high-resolution camera system that captures 20 images per second. The resulting footage shows individual nests measuring about 75 centimeters across, each holding an average of 1,700 eggs.
Male fish were seen guarding nearly 85% of the nests identified in the Filchner Trough area. That level of parental defense is notably high for a fish species, and it suggests the eggs face real predation pressure at the site.
To build its picture of the seafloor, LASSIE holds a constant altitude of 1.5 meters above the rugged terrain using a specialized buoyancy control system. It carries side-scan sonar and a laser-line scanner to generate three-dimensional maps of the nesting grounds as it moves.
Those maps let biologists measure the spacing between individual nests, which averaged just 22 centimeters in recent samples. That is an exceptionally tight clustering to maintain across such a large area of seabed.
Initial deployment data put the colony’s total biomass at approximately 60,000 tonnes, giving researchers a clearer sense of just how much living material this single breeding ground supports.
Why the Fish Need a Narrow Band of Warmer Water
The breeding site sits in a region where Modified Upper Circumpolar Deep Water (mUCDW) flows onto the continental shelf. This inflow shapes the conditions that make the colony possible in the first place.
A study published in Frontiers in Marine Science described how this relatively warmer water keeps the local seabed from reaching the freezing point of seawater. Without that buffer, conditions at the site would likely be too harsh for the eggs to survive.
Researchers found that Jonah’s icefish (Neopagetopsis ionah) selectively build their nests in spots where water temperatures stay between 0°C and 0.5°C. That narrow thermal window appears essential for their eggs to develop properly.
Icefish are unusual among vertebrates because they lack hemoglobin and red blood cells altogether. That rare adaptation reduces blood viscosity and lets them survive in sub-zero water, though it also leaves them highly dependent on oxygen-rich currents flowing past their gills.
Documentation from the site shows that the Filchner Trough current supplies a steady flow of oxygenated water across the nesting grounds. That current sustains tens of millions of developing embryos through their incubation period.
Nest Construction and a Localized Ecosystem
LASSIE’s footage confirmed that the nests vary somewhat in construction, though most follow the same basic pattern. Each is a circular depression cleared of fine sediment, exposing a base of gravel and small stones underneath.
That structure stabilizes the eggs inside and keeps them from being displaced by passing currents. It is a simple design, but one that appears consistent across the vast majority of nests surveyed.
Sensor readings show silt levels inside the nests running about 40% lower than in the surrounding, undisturbed seabed. That gap suggests the fish are actively maintaining their nests rather than simply digging them once.
The survey also documented carcasses and abandoned nests scattered along the colony’s edges. These areas draw scavengers, including sea stars, brittle stars, and other crustaceans that feed on dead organic matter.
The concentration of that organic material has created a localized ecosystem that is noticeably more diverse than the neighboring deep-sea plains, where such food sources are scarce.
Weddell Seals and a Push for Protection
Weddell seals are the colony’s primary predators, and the AWI team cross-referenced LASSIE’s footage against acoustic recordings from hydrophones moored at the site. The two data sets together give a fuller picture of how seals use the colony.
The data show a clear correlation between peak spawning periods and a rise in seal vocalizations nearby. That pattern held consistently across the recordings collected during the survey.
Satellite tracking indicates that 90% of seal diving activity in this part of the Weddell Sea occurs directly above the colony’s coordinates. Hydrophone sensors also recorded more than 2,000 seal dives reaching depths of 400 to 500 meters during November alone.
The colony’s scale and ecological role have prompted a proposal to designate the region as a Marine Protected Area (MPA), submitted to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). The proposal cites the site’s vulnerability to bottom trawling as well as the risks that climate-driven changes in deep-water circulation could pose to the colony over time.
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