Human noise contributes to reducing posidonia populations

In the last hundred years many sources of man-made noise in the marine environment that have been shown to adversely affect marine organisms. The critical hit noise and other forms of energy in the natural balance of the oceans has been little studied in many respects. Much attention has been paid to determining noise sensitivity of fish and marine mammals, especially cetaceans and pinnipeds, because they are known to possess hearing organs.

Recent studies, carried out at the Laboratory of Bioacoustic Applications (LAB) of the Universitat Politècnica de Catalunya BarcelonaTech (UPC) and whose results are published by Nature Communications Biology, have also shown that the cephalopods, anemones and jellyfishAlthough they lack similar auditory receptors, they are also affected by artificial sounds.

Marine invertebrates have sensory organs that allow them to maintain balance and perceive gravity in the water column

In fact, marine invertebrates have sensory organs that allow them to balance and sense gravity in the water column. But, interestingly, not a single study has yet addressed the noise sensitivity of sessile marine organisms, such as plants or coral reefs, whose immobility makes them highly susceptible to chronic effects, since these species also have sensory organs specialized in the perception of gravity, which are essential to find their natural substrate.

The Posidonia It is already in a fragile situation due to threats of human origin due to the massive use of the anchors of pleasure boats, which literally uproot these unique seagrasses.

An essential species for marine life

Seagrasses are considered an equivalent of the primary forests as regards its ecological functions. They are superior plants adapted to the marine environment, which develop vital ecosystems that consist of thousand-year-old complex networks, anchored in soft bottoms. They have a significant effect on both biodiversity As in ecosystem functions, they minimize hydrodynamic forces, influence host species (invertebrates and fish), and promote the growth of microbiomes and bacteria.

They also have starch grains in their roots that function like statocysts in invertebrates, sensory organs responsible for detecting gravity and processing sound vibration. Also, its horizontal stems, rhizomes, which act as storage organs, contain a considerable amount of starch grains, guaranteeing the energy supply of the plants.

Low-frequency sounds not only produce alterations in the root and rhizome statocysts of the posidonia oceanica, but the nutritional processes of the plant can also be affected.

The study, led by Marta Solé, senior researcher at the UPC LAB, describes morphological and ultrastructural changes in seagrass beds after being exposed to sounds in a controlled environment. “These changes are new in the pathology of aquatic plants. low frequency sounds not only do they produce alterations in the statocysts of the root and rhizome of the oceanic posidonia, but the nutritional processes of the plant can also be affected by a decrease in the number of starch grains in the rhizome “, they explain from the UPC.

Finally, a degradation has been observed in symbiotic fungi specific to the roots of the posidonia oceanica. The fungi improve the nutritional status of the plant (mineral nutrition, water absorption) in exchange for obtaining the necessary carbon for its growth and reproduction from the posidonia.

“This sensitivity to artificial sounds shows how sound can potentially affect the health status of posidonia oceanica. Furthermore, these findings point to the need to quantify the impact of increased ocean noise pollution in the reduction of seagrass populations and in the loss of biodiversity in the future “, they conclude.

Rights: Creative Commons.

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