The preservation of marine fossils is highly influenced by human endeavors, resulting in consequences that both cloud and clarify our historical perception of ecosystems. Progress in inquiry methodologies is assisting researchers in navigating these intricacies for improved conservation and rehabilitation of marine habitats.
New findings demonstrate that human activities are significantly altering the preservation of marine organisms, leading to enduring implications that can either enhance or degrade the fossil account.
“We are not simply altering the surroundings; we are also transforming the essence of the record documenting this information,” stated Michal Kowalewski, the Thompson chair of invertebrate paleontology at the Florida Museum of Natural History. “These modifications can have positive and negative impacts. While human actions can impede the fossil record from conserving valuable details about ongoing changes, in other scenarios, they can actually improve the quality of the current fossil record, thereby offering more insights.”
If not appropriately considered, these influences on the fossil record can result in misinterpretations of data crucial for conservation initiatives. Human interventions began reshaping ecosystems long before systematic examination began. In numerous instances, the only way scientists can visualize pre-human ecosystem states is by studying the recent fossil record.
“We utilize fossils in conservation to comprehend the shift from untouched, natural environments to current conditions,” Kowalewski remarked. By understanding what a degraded ecosystem resembled before modification, scientists can aim towards reinstating it.
Kowalewski and collaborators specialize in marine paleoecology and co-wrote the investigation focusing on fossil deposits in global oceanic areas. In these settings, the researchers indicate several interconnected elements affecting fossilization, such as sediment accumulation rate on the seabed, animal burrowing intensity, burial depth of remains, and the degradation rate of specific fossils over time.
The Impact of Bottom Trawling
All these aspects have been and can be influenced by human actions. The method of bottom trawling, involving dragging a net along the seafloor, stirs and mixes sediment, infusing it with oxygen that accelerates the decomposition of organic remains.
Globally, the practice of bottom trawling is approximated to suspend as much sediment into the water column as deposited by all the world’s rivers into oceans.
“I was taken aback while researching this study by the extensive repercussions of bottom trawling,” stated primary author Rafal Nawrot, a paleontologist at the University of Vienna. Nawrot examines alterations in marine ecosystems post the last ice age, a domain where understanding the various factors aiding or obstructing fossilization is crucial.
He recollected a particular study where a noticeable absence of sizable shells was evident in sediment cores retrieved from the seafloor. “Given our current awareness of the trawling intensity in regions we surveyed, this pattern might simply result from their removal by the nets dragged along the seafloor.”
Unintentional Outcomes of Human Interventions
Modifications to the fossil record can have indirect implications as well. Local extinctions triggered by human influence and the introduction of invasive species can hinder and enhance the fossilization process. For instance, the authors cite the case of red king crabs (Paralithodes camtschaticus), deliberately introduced into the Barents Sea between Russia and Finland in the 1960s. With limited natural predators, the crab population surged. Red king crabs have a broad diet and crush the shells of their prey, leading to a significant decline in burrowing shellfish populations.
A decrease in burrowing creatures leads to lower sediment oxygen levels, resulting in improved preservation. However, an increase in shell-breaking crabs reduces the shells available for preservation. Without proper historical context, future paleontologists attempting to unravel this sequence of events might end up baffled.
Human-induced alterations, like erosion or species movements, can pose significant challenges in interpretation. At times, human activities can completely erase fossil records or complicate research endeavors by introducing excessive foreign materials into an environment.
“Certain activities like beach nourishment do not occur naturally,” mentioned Kowalewski. In instances where sections of a beach are eroded by hurricanes or rising sea levels, authorities often opt for sediment transport from deep-water areas with minimal natural erosion to the shore, carrying fossil remains along.
In other scenarios, fossils themselves are relocated intentionally.
“Oysters that existed hundreds of millennia ago might be relocated from one site to the present-day seabed to aid in the restoration of contemporary oyster reefs,” explained Kowalewski.
Therefore, disentangling the intertwined natural and human influences on fossilization presents a complex challenge. According to Nawrot, “It varies based on the study objectives, but there are methods to address these issues.”
One increasingly viable strategy is radiocarbon dating. While traditionally expensive, scientists now employ this technique for estimating the age of relatively young fossils. In the past, due to high costs, researchers would only radiocarbon date a few fossils from a sediment core extracted from modern seafloors where organisms at the top may be substantially younger than those at the bottom. This method offered reliability but limited resolution, and mixing of sediments through bottom trawling could lead to misleading results if not identified.
“The sampling of multiple specimens per layer is not a common practice, but it is essential to be aware of potential issues. It should be more widely adopted,” Nawrot suggested.
Furthermore, researchers must explore innovative statistical analyses to interpret data effectively. These analytical methods require time for development and testing, but they are gradually gaining popularity. Scientists are progressing towards a deeper comprehension of how human activities impact the historical documentation of life on Earth.
“Changes in the geological record serve as indicators of human influence and may offer insights into the ecosystem’s historical trajectory,” reflected Kowalewski.
Image Source: Paulo Miguel Costa / Shutterstock
