A fjord is a long, narrow, and deep inlet of the sea, typically set between high cliffs or mountains. These are submerged U-shaped valleys carved out by glaciers during past ice ages. When the ice sheets retreated and sea levels rose, the valleys flooded with ocean water. This process created a unique coastal environment found primarily in high-latitude regions, such as Norway, Greenland, Chile, and New Zealand. Fjords are important environments that host distinct biological communities and possess significant scientific value.
Unique Deep Water Structure
The defining physical characteristic of a fjord is the presence of a shallow underwater ridge at its mouth, known as a sill or threshold. This sill is formed from less-eroded bedrock or accumulated glacial debris. Some fjords, like Norway’s Sognefjord, plunge over 4,200 feet deep, yet their sills may be hundreds of feet shallower. The sill restricts the exchange of deep water between the inner fjord basin and the open ocean, limiting the flow of oxygen-rich bottom water. This restricted circulation creates distinct layers of water with varying temperatures, salinity, and oxygen levels, which is the reason for the specialized ecology and oceanographic research value of fjords.
Specialized Marine Ecosystems
Hydrological Conditions
The physical structure of a fjord creates unique hydrological conditions that foster specialized marine ecosystems. Freshwater runoff from rivers, glaciers, and rain is less dense than saltwater, causing it to form a surface layer. This stratification influences nutrient distribution and light penetration for plankton communities. The deep, stable, and sheltered waters provide habitats unusual for coastal areas.
Biodiversity and Research
The presence of deep basins close to shore allows deep-sea organisms to live much closer to the surface than they would in the open ocean. This allows scientists to study deep-water species, such as Greenland sharks and mesopelagic fish, with relative ease. Fjords also serve as biodiversity hotspots, sometimes containing species found nowhere else. Deep-water coral reefs have been discovered in the cold, dark depths of some fjords. The combination of glacial meltwater, deep basins, and restricted exchange supports complex food webs, including salmon, seals, and whales.
Economic and Cultural Value
Historical Significance
Fjords have long held importance for human settlement and economic activity. Historically, the sheltered inlets served as natural harbors and protected maritime highways, facilitating transportation and trade. This network of navigable waterways was instrumental in the development and cultural identity of regions like Scandinavia.
Modern Economic Uses
The most visible economic contribution of fjords today is the high-value tourism they support. The scenery, characterized by towering cliffs and plunging waterfalls, attracts millions of visitors annually for cruising and sightseeing, generating substantial revenue. Fjords also provide ideal conditions for aquaculture, particularly for salmon and fjord trout farming. The cold, clear, and deep waters offer a stable environment for raising fish. Norway, for example, uses its extensive fjord system to produce a large portion of the world’s farmed salmon.
Scientific Archives of Climate History
Fjords are valued by scientists as high-resolution archives of environmental change. The deep, stable basins have low-energy environments where fine sediments accumulate with minimal disturbance. This sedimentation, often influenced by freshwater and glacial meltwater, creates layers that contain a continuous record of past conditions. Scientists extract long sediment cores to reconstruct past climate change, glacier movements, and ocean circulation patterns over thousands of years. These cores contain pollen, microfossils, and chemical signatures, and the restricted water exchange sometimes leads to anoxic conditions that perfectly preserve the layered record for paleoclimate research.