All the way through an afternoon on the seaside, it’s not unusual to peer folks strolling up and down the shore gathering seashells.
As a paleontologist and marine ecologist, we have a look at shells a bit of another way than the common beachcomber. The general public dig up shells within the sand and notice gorgeous colour patterns or bizarre shapes. However we have a tendency to concentrate on how previous those shells are and what they let us know concerning the habitat they arrive from.
You can be stunned to be told that the translucent spiral shell you plucked from the sand belonged to a snail that lived lengthy earlier than Columbus sailed to the New International. And that unassuming clamshell you could nonchalantly toss away belonged to a mollusk that filtered seawater when pharaohs dominated Egypt.
In contemporary many years, scientists have used strategies reminiscent of radiocarbon courting to evaluate the age of shells, at the side of bones and different skeletal stays, scattered round Earth’s floor.
Increasingly more, paleontologists and conservation biologists like us are turning to those stays as attainable treasure troves of details about what more than a few habitats have been like earlier than people entered the image. The insights we glean from this method, referred to as conservation paleobiology, can lead to more practical conservation, recovery and control methods aimed on the coverage or restoration of many crucial habitats.
This method has proved, amongst different issues, that cows reshaped shellfish communities at the California shelf, caribou used the similar calving grounds for millennia, and Caribbean sharks have been a lot more various up to now.
Over the last decade, we have now carried out conservation paleobiology to Florida’s Nature Coast, house to an intensive and complicated patchwork of seagrass meadows and sand. Previous to our research, scientists’ figuring out of the ones meadows was once in large part uninformed by way of ancient knowledge.
A curious younger manatee approached our workforce of medical divers at paintings in Wakulla Springs in Would possibly 2020. This charismatic marine mammal inhabits seagrass meadows alongside Florida coasts, however within the wintry weather and spring it shelters in heat waters of Florida springs and rivers.
Michal Kowalewski
Why seagrass issues
It might not be obtrusive to start with look why we must have an interest up to now historical past of seagrass meadows.
However those meadows are a few of the maximum vital structural habitats on our planet. Myriad species, together with sea turtles and manatees, forage, safe haven or reproduce in the ones habitats, making seagrasses primary sizzling spots of biodiversity.
Past those advantages, seagrasses be offering extraordinarily treasured products and services. They oxygenate ocean waters, draw down carbon dioxide and stabilize backside sediments. And seriously for Florida’s beach, seagrass can hose down wave power, which is helping to offer protection to shorelines and coastal communities from the punishing results of tropical storms and hurricanes.
By way of offering most of these products and services, seagrasses gasoline an incredible financial engine that generates world earnings in way over US$6 trillion yearly, consistent with an research printed within the magazine Nature Critiques Biodiversity in February 2025.
Sadly, seagrass meadows are in decline globally, vanishing unexpectedly because of broad-scale environmental adjustments and an onslaught of native human affects. Efforts are underway in every single place the sector to offer protection to seagrasses that also exist and repair the ones which were misplaced.
Present in Citrus County, Florida, in 1989, this outstanding rock slab preserves more than one blades of seagrass, proving that those grasses had been round Florida for a minimum of 40 million years.
Roger W. Portell, Florida Museum of Herbal Historical past
Shells in Florida’s seagrass meadows
The problem inherent to our analysis is that seagrasses don’t have a difficult skeleton, so they’re very hardly ever discovered within the fossil report.
Thankfully, we discovered that the shells of mollusks that like to reside in seagrass are a competent proxy for the grass itself. Basically, the standard of ecological knowledge equipped by way of fossil shellfish is phenomenal.
When dwelling and useless organisms are alike, we will infer that native ecosystems have no longer modified particularly in spite of human actions. Conversely, when are living and useless mollusk species vary, it typically is an indication {that a} habitat has been closely altered by way of people.
Location, location, location
In our preliminary find out about, our workforce tested a couple of 40-mile (65-kilometer) swath of nearshore habitats in a space simply north of the Suwannee River.
We discovered that seagrass meadows incessantly span only some acres, forming a regional patchwork of vegetated and open-sand habitats. We additionally seen that distinct units of mollusk species inhabit meadows and open sands these days. This was once no longer sudden, as many earlier research have proven that other mollusks are living in seagrass and open-sand habitats.
Subsequent, we appeared on the shells of useless mollusks present in floor sediments within the space. The use of radiocarbon courting, we confirmed that about part of those shells belonged to mollusks that lived previous to the Commercial Revolution. Many shells dated again to earlier millennia.
If those small patches of seagrass meadows have been waxing, waning or moving location over the hot centuries, then we might be expecting every spot at the seafloor to harbor a mixture of useless shells representing species from each habitats. Then again, we discovered that the species of useless mollusks in seagrass patches have been remarkably very similar to those who are living there now. The similar was once the case for the mollusks from open sands.
This implies that this mosaic of seagrass patches and open-sand bottoms has been remarkably solid for centuries. We have no idea why the seagrass persistently thrived for hundreds of years in particular spots inside of a reputedly uniform setting. However regardless of the reason why, this habitat isn’t a mosaic of meadows in consistent flux, however moderately, a seascape that has remained the similar for a very long time.
That is crucial in finding for conservation efforts. It implies that it can be unwise to think that we will catch up on seagrass losses by way of merely planting new meadows in open-sand habitats.
Those mollusk shells have been accumulated by way of divers from Florida seagrass meadows in Tampa Bay in October 2025. Such shells generally supply a report of numerous organisms that inhabited the world over loads of years.
Invertebrate Paleontology Department, Florida Museum of Herbal Historical past
Broadening the scope
In our latest find out about, we broadened our scope to match dwelling mollusks and useless mollusks throughout more than one estuaries alongside the Nature Coast, a 93-mile (150-kilometer) stretch of Florida’s Gulf Coast.
As with our first find out about, this broader find out about published many exceptional similarities between the mollusks that are living there now and the mollusks from earlier centuries and millennia, documented by way of shells.
We discovered that the mollusks which might be not unusual these days and people who have been not unusual up to now constitute nearly the similar suite of species, and their relative abundance stayed secure, too.
Much more remarkably, each the are living mollusks and shells from earlier centuries file the similar adjustments in dominant mollusk species between the southern and northerly areas of the find out about space.
As of late, mollusks aren’t the similar in all places alongside the Nature Coast. This displays the truth that coastal waters are an increasing number of nutritious within the north. As a result, seagrass is taller and denser transferring north, and the suites of mollusk species that are living in them exchange as smartly.
The shells of useless mollusks inform the similar tale. This means that no longer a lot has modified alongside this stretch of the Gulf Coast since preindustrial occasions.
Highlighting what’s running
Realizing that seagrass meadows on this space have maintained their ecological persona and integrity for hundreds of years or longer is a formidable argument for his or her persevered coverage.
Understandably, maximum conservation paleobiology research have thinking about threatened species, degraded habitats or imperiled methods, reminiscent of reef sharks, oyster beds or freshwater mussels. In consequence, those research in most cases file inhabitants cave in, biodiversity loss, habitat shrinking and general ecosystem decline.
However we consider it’s similarly vital for investigators in our box to review methods which might be believed to be solid and resilient. On this case, the unspoiled standing of the Nature Coast seagrass meadows makes them a much-needed benchmark to evaluate the state of different seagrass methods which were altered by way of human actions. This may be offering insights into which conservation efforts are running and the way perfect to revive and handle an identical habitats somewhere else.
