Undersea mountains, known as seamounts, function remarkably as critical hotspots for marine predators, leading to astounding concentrations of species such as sharks and tuna. The recent groundbreaking research led by the University of Exeter and the Ascension Island Government uncovers just how significant these geothermal formations are in the South Atlantic Ocean. The study reveals that shallow seamounts harbor 41 times more sharks than the surrounding open ocean, inspiring conservation efforts and rethinking our understanding of marine ecosystems.
The researchers focused on three specific seamounts off the coast of Ascension Island, where two of these geological structures are characterized as shallow, their peaks standing less than 100 meters beneath the ocean’s surface. This unique topography has provided an ecological sanctuary that teems with predatory life. The findings highlight an unprecedented abundance of both large and small marine species in these areas, contributing to their classification as crucial environmental oases.
Dr. Sam Weber, associated with the Centre for Ecology and Conservation at the University of Exeter, articulated the key characteristics that make seamounts special. He noted, “Seamounts have long been referred to as ‘oases of life’ within the expansive, barren stretches of open sea.” However, historical data on the biological activity around these formations has remained scarce. This study fills that research gap, revealing the complex ecological dynamics at play.
One of the critical insights derived from this investigation is that the usual assumptions about primary productivity do not hold true in these locations. Traditionally, it was believed that increased phytoplankton growth at seamounts would lead to higher food availability for marine predators. However, the study found no evidence to support this. Despite the lack of enhanced levels of phytoplankton at the Ascension seamounts, the biomass measurements presented a clear picture: predatory life flourishes remarkably well.
A striking finding was the observed biomass of zooplankton, which was shown to be twice as plentiful at the shallow seamounts compared to the open ocean. This indicates a shift in the food web that fosters an environment ripe for larger predators. Sharks, in particular, which thrived in these underwater extensions, showcased biomass levels 41 times higher than those recorded in adjacent open ocean waters. This statistic underscores the ecological importance of these underwater landscapes.
The research proposes that seamounts serve multiple roles that collectively enhance their attractiveness to marine life, especially apex predators. Not only do they create physical barriers that filter prey and limit their escape routes, but they may also act as social meeting points for marine species. Sharks and other predators perhaps utilize these areas as hubs where they can interact socially, mate, forage, and recuperate after hunting in the more extensive oceanic expanses.
The investigation also indicated the presence of a so-called ‘halo’ effect around the seamounts. This phenomenon refers to the increased prevalence of marine life extending at least 5 kilometers into the surrounding waters, suggesting that these structures have biological significance that extends beyond their immediate vicinity. As such, scientists explore what conservation measures can be employed to protect these vital marine areas.
The significance of the research is amplified by the fact that all examined seamounts lie within the Ascension Island Marine Protected Area, where strict regulations are enforced against large-scale commercial fishing and seabed mining activities. The study reaffirms the ecological value of such protective measures for sustaining marine diversity and bolstering populations of key predator species.
Additionally, the use of advanced research methodologies onboard the British Antarctic Survey’s research vessel, the RRS James Clark Ross, enabled researchers to gather critical data to underpin their findings. State-of-the-art technologies facilitated detailed studies, offering clearer insights into the rich marine biodiversity that thrives around these oceanic mountain ranges.
In conclusion, the research findings compel us to reconsider the role of seamounts in sustaining marine ecosystems. The phenomenal concentrations of predators, such as Galapagos and silky sharks, which are known to frequent these underwater plateaus, reveal that conservation strategies must be prioritizing these ecological wonders. Seamounts not only act as necessary habitats for vital marine species but may also have broader implications for the health and balance of ocean ecosystems globally.
This novel investigation adds a rich layer of understanding to our ecological narratives, showcasing how integral these underwater features are to the ocean’s ecological tapestry. Understanding the dynamics of seamounts sets a vital precedent for future conservation endeavors aimed at preserving these unique and essential marine habitats.
Subject of Research: The significance of shallow seamounts in supporting marine predator populations.
Article Title: Shallow seamounts are “oases” and activity hubs for pelagic predators in a large-scale marine reserve
News Publication Date: 14-Feb-2025
Web References: PLOS Biology
References: Journal of PLOS Biology
Image Credits: Credit: Ascension Island Government Conservation & Fisheries Directorate
Keywords: Marine conservation, seamounts, ecological dynamics, predator populations, biodiversity, Ascension Island, marine protected areas, ocean ecosystems.
