Breakthrough Cover Story Illuminates Hadal Zone Secrets

The March 6, 2026, issue of Cell, a flagship journal from Cell Press, spotlights the Mariana Trench Environment and Ecology Research (MEER) project led by Chinese scientists. This cover story collection features one commentary and three groundbreaking research articles, offering the first comprehensive map of life in the hadal zone—the ocean's deepest layer exceeding 6,000 meters. Previously, exploration was limited; before 2020, only nine humans had reached Challenger Deep, the trench's nadir at nearly 11,000 meters.

Under crushing pressures up to 1,100 times atmospheric levels, perpetual darkness, near-freezing temperatures, and scarce nutrients, scientists expected barren depths. Instead, MEER reveals a thriving ecosystem, challenging assumptions and positioning China at the forefront of deep-sea science through institutions like Shanghai Jiao Tong University (SJTU) and the Chinese Academy of Sciences (CAS).

MEER Project: China's Technological Leap into the Abyss

Launched in 2021, the MEER project unites SJTU's International Center for Deep Life Investigation, BGI Group, CAS's Institute of Deep-sea Science and Engineering in Sanya, and international partners. During the 2021 TS21 expedition aboard R/V Tan Suo Yi Hao, the full-ocean-depth manned submersible Fendouzhe—capable of 11,000-meter dives—conducted 33 missions, collecting 227 push-cores yielding ~1,700 stratified sediment samples, 12 in situ filtered seawater samples, and macrofauna like amphipods and fishes from Mariana, Yap Trench, and Philippine Basin.

Semiautomated DNA extraction and high-throughput sequencing (DNBSEQ-T) generated ~92 terabases of metagenomic data— the largest hadal microbial dataset. Public portals like Biosino.org/mash/meer host this treasure trove, fostering global collaboration. This infrastructure underscores China's deep-sea prowess, from submersible engineering to bioinformatics, inspiring marine biology programs nationwide.

Hadal Zone Defined: Earth's Untouched Frontier

The hadal zone, named after Hades, spans trenches formed by tectonic subduction, comprising just 1-2% of seafloor but 45% of ocean depth range. Extreme hydrostatic pressure (110 MPa at 11 km) warps proteins, while low temperatures (~1-4°C) and food scarcity demand unique survival tactics. MEER's stratified sampling (0-30 cm sediments) reveals vertical gradients: surface diversity peaks, deepening layers favor specialized microbes.

Historically, sampling relied on landers or rare submersible trips. MEER's precision—via Fendouzhe's push-cores—unlocks layered insights, revolutionizing how universities train oceanographers in extreme environment sampling.

Microbial Marvels: Novelty and Diversity Beyond Imagination

MEER identified 7,564 species-level representative genomes (SRGs), 89.4% novel to global databases like GTDB. Amplicon sequencing yielded 345,311 ASVs, 60% unmapped. Shannon diversity (~5.5) rivals surface oceans, with Bray-Curtis dissimilarity (0.75-0.86) highlighting heterogeneity.

• Top phyla: Pseudomonadota, Chloroflexota (bacteria); Thermoproteota, Nanoarchaeota (archaea).
• Three mystery SRGs (MEER-01/02/03) defy phylum assignment (RED 0.28-0.35).
• Vertical zonation: Diversity drops with depth; prokaryotic networks complexify (degree 2.36 surface to 23.27 at 20-30 cm).

These microbes process refractory organics via aromatic degradation (e.g., toluene etbAa), vital in nutrient-poor sediments.

Photo by Wolfgang Hasselmann on Unsplash

Two Microbial Lifestyles: Streamlined vs. Versatile Survivors

Ecological analysis via iCAMP classifies hadal microbes into guilds: Habitat Specialists (HoS, 50.5%) with streamlined genomes for oligotrophy—small size, focused metabolism on antioxidants (prdx5) and endocytosis (vps genes); Dormancy Leaders (DL, 43.8%) with versatile sensing (two-component systems vicKR), biofilms, flagella; minimal Dormancy Responders (DR, 1.4%).

HoS thrive near-surface, degrading pollutants; DL dominate depths, adapting to redox shifts (nitrite reduction nasB). This dichotomy explains resilience, informing synthetic biology curricula at Chinese universities like SJTU.

Macrofauna Adaptations: Convergent Evolution Across Domains

Beyond microbes, MEER sequenced amphipod Hirondellea gigas (622 specimens, 13.92 Gb genome, >70% repeats) genome, revealing no depth differentiation but basin-specific variations. Fishes like Pseudoliparis swirei show vertical invasion from abyssal depths, retaining bioluminescent vision genes, rtf1 mutations for pressure-stable proteins.

Convergent traits—antioxidation, osmolyte accumulation (e.g., TMAO, though stable below 6 km)—link prokaryotes, eukaryotes. A food web emerges: microbes fuel amphipods, sustaining fishes.Explore research positions in evolutionary genomics at leading Chinese labs.

Human Footprint: Pollutants in the Deepest Reaches

Persistent organics (POPs) contaminate Challenger Deep sediments and fish, tracing surface pollution via sinking particles. This underscores global connectivity, urging conservation policies. MEER data portals enable worldwide monitoring studies.

For more on environmental science careers, check China higher ed opportunities.

Chinese Universities Driving Global Deep-Sea Innovation

SJTU Prof. Xiang Xiao leads, with CAS Sanya and BGI providing genomics muscle. Hainan Tropical Ocean University contributes locally. This prowess stems from national investments in submersibles, sequencing—training next-gen via interdisciplinary programs.

BGI's China National GeneBank hosts amphipod/fish data (CNP0003471, PRJNA1138967), accelerating discoveries.

Photo by dani grau on Unsplash

Implications for Biotechnology and Astrobiology

Novel genes promise extremophile enzymes for pharma, bioremediation. Convergent adaptations mirror potential extraterrestrial life, aiding space biology research. Open data democratizes access, boosting international collaborations.

Future Expeditions and Educational Horizons

MEER phase two eyes expanded sampling, modeling. China's deep-sea stations planned enhance sustained research. Universities ramp marine PhDs, linking to postdoc openings.

In conclusion, MEER redefines deep-sea ecology, showcasing Chinese higher ed excellence. Aspiring researchers, visit Rate My Professor, higher-ed-jobs, career advice, university jobs, or post a job.