SEABIRDS ARE FASCINATING CREATURES, PERFECTLY ADAPTED TO LIFE IN THE OPEN OCEAN, AND THEY ALSO SERVE AS IMPORTANT INDICATORS OF THE HEALTH OF MARINE ECOSYSTEMS.
Salt gland
Seabirds are a group of avian species that inhabit coastal areas and open oceans worldwide. These creatures have evolved unique adaptations that enable them to thrive in marine environments and contribute to various ecological processes.
One of their adaptations is the presence of a specialized organ called the salt gland, located above their eyes, which allows them to excrete excess salt from their bodies, maintaining a proper salt balance and preventing dehydration. Seabirds consume saltwater and salty food, so the salt gland actively removes the surplus salt from their bloodstream and secretes a concentrated saline solution through the nostrils or a duct near the eyes. By excreting excess salt, seabirds can thrive in their saline environment and endure long periods without freshwater sources.
Seabirds occupy the upper levels of the marine food chain, regulating the populations of their prey species. By feeding on fish, squid, crustaceans, and other marine organisms, seabirds help control the abundance and distribution of these prey populations. This predatory pressure helps maintain the balance of the ecosystem, preventing the uncontrolled proliferation of some species and ensuring the survival of others.
Northern Gannets (Morus bassanus), known as the "Queens of the Sea," are masterful hunters renowned for their incredible diving prowess. Soaring from great heights, they fold their wings and plunge into the water at breathtaking speeds, resembling swift missiles in flight. With astonishing precision, they enter the water at speeds of up to 24 m/s. Underwater, they navigate with streamlined grace, diving as deep as 15 meters to seize their prey using their sharp, dagger-like bills.
Emperor Penguins (Aptenodytes forsteri) diving
video source: Canva.com
photo credit: © National Geographic Creative / Paul Nicklen / WWF
The Emperor Penguin (Aptenodytes forsteri) holds the record for the deepest dive among birds, reaching depths exceeding 530 meters (1,740 feet). Equipped with remarkable adaptations, such as increased oxygen storage and streamlined bodies, these penguins can endure the pressures and cold temperatures of the Southern Ocean. Their dives last for several minutes, allowing them to forage on fish, squid, and krill.
Seabirds are efficient scavengers, playing a crucial role in nutrient cycling within marine ecosystems. They consume carrion and organic debris found in the ocean, helping to break down and recycle nutrients back into the ecosystem. As seabirds obtain nutrients from their food sources, they release them through their excrement, enriching the surrounding waters and providing nourishment for phytoplankton and other marine organisms. This process underscores their vital contribution to maintaining the health and balance of marine environments.
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THE SEABIRD MIGRATION IS CRUCIAL FOR ECOSYSTEM BALANCE AS IT FACILITATES THE TRANSFER OF NUTRIENTS BETWEEN MARINE AND TERRESTRIAL ENVIRONMENTS, CONNECTING DISTANT HABITATS, CONTRIBUTING TO BIODIVERSITY, AND SUSTAINING VARIOUS SPECIES.
Seabirds are renowned for their long-distance migrations.
Many species undertake incredible journeys, crossing vast expanses of the Ocean to reach breeding grounds or find food. These migratory patterns facilitate the exchange of energy and nutrients from one area to another through their feeding and excretion activities. This movement of nutrients is crucial for maintaining the productivity and biodiversity of various marine ecosystems.
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One of the most extraordinary migratory events in the avian world is undertaken by the Sooty Shearwater (Puffinus griseus), a seabird renowned for its remarkable journeys across the Earth's oceans. Every year, these birds embark on an epic migration, covering an astonishing distance of over 64,000 kilometres (40,000 miles) on a round trip between their breeding grounds and wintering areas. They spend about eight months in the air, covering an average of 500 kilometres (310 miles) per day, contributing to marine ecosystems along their journey. By transporting nutrients and energy from the rich feeding areas of the southern oceans to the more nutrient-poor regions of the northern oceans, they contribute to the overall health and productivity of marine ecosystems.
Migratory paths of the Sooty Shearwater (Puffinus griseus)
image source: Shaffer et al. 2006, Proc. Natl. Acad. Sci. 103: 12799-12802.
SEABIRDS ARE IN GRAVE DANGER DUE TO PLASTIC POLLUTION, CAUSED BY HUMAN ACTIVITIES.
Plastic pollution poses a critical threat to seabirds, with millions falling victim each year.
Seabirds often mistake plastic debris for food, ingesting fragments and particles that lead to internal injuries, digestive blockages, and malnutrition, hampering survival and reproduction. Fishing lines, nets, and packing straps also entangle seabirds, resulting in injuries, restricted movement, and vulnerability to predators. That decreases foraging efficiency, breeding success, and overall population.
Moreover, plastic materials can act as a sponge for harmful chemicals. As seabirds ingest these plastics, they can be exposed to a high concentration of these toxic substances, leading to chronic health issues and impaired immune systems.
