Seal poop, scientifically known as scat, holds surprising significance in understanding ocean environments. Far from being mere refuse, it serves as a rich source of information for scientists and plays an unexpected role in the health of marine ecosystems.
What is Seal Poop?
Seal poop exhibits various physical characteristics depending on the seal’s diet. It typically appears as a dark, often greenish-black or reddish-brown mass, with a consistency that can range from firm and well-formed to more liquid or amorphous, especially if the seal has recently consumed oily prey. The color and texture are direct indicators of what a seal has been eating; for instance, a diet rich in crustaceans might result in reddish scat due to pigments from the shells, while a fish-heavy diet often produces darker, more uniform stools.
Hard parts from prey, such as fish bones (otoliths), scales, and squid beaks, are frequently visible within the scat, providing visual cues about the seal’s recent meals and foraging habits. The basic composition includes digested food matter, metabolic byproducts, and undigested components from their prey.
Why Scientists Study Seal Poop
Scientists analyze seal scat to gather valuable information about seal populations and marine environments using non-invasive techniques. One common method involves identifying hard parts like otoliths (fish ear bones) from the scat to determine the seal’s diet, including prey species, size, and biomass. This approach provides a snapshot of what seals have consumed over the past day or two.
Further analysis includes DNA sequencing of scat, which can identify prey species at a finer taxonomic level, even detecting invertebrates that might be missed by hard-part analysis. DNA analysis can also reveal genetic information about the individual seal, contributing to population dynamics studies. Researchers also examine scat for hormones, which can indicate stress levels or reproductive status, and identify parasites, offering insights into seal health and disease prevalence.
Seal Poop’s Role in Marine Ecosystems
Seal waste contributes significantly to nutrient cycling, acting as a natural fertilizer for marine waters. When seals consume prey at various depths and then release their waste near the surface, they transport nutrients from deeper waters upwards, a process akin to the “whale pump” observed in larger marine mammals. This upward movement of nutrients helps to replenish surface waters, which are often depleted of these elements.
The feces contain essential nutrients like nitrogen, phosphorus, and iron, which are otherwise scarce in some ocean regions. These nutrients are utilized by microscopic marine algae, known as phytoplankton, for photosynthesis. Phytoplankton form the base of the marine food web, producing a substantial portion of the Earth’s oxygen and supporting virtually all marine animal life. By stimulating phytoplankton blooms, seal poop indirectly supports the entire marine food chain.