Paleoenvironmental research at Waterfall Bluff reveals leopard seal removed from Antarctic waters

Waterfall Bluff Rock Shelter (WB) (Eastern Cape Province (ECP), South Africa) accommodates archaeological deposits demonstrating persistent and steady human occupation spanning from Late Marine Isotope Stage 3 (~39ka–29ka) to the mid-Holocene (~8ka). It is at this web site that the primary leopard seal (Hydrurga leptonyx) specimen was lately recovered from a Pleistocene and Holocene zooarchaeological assemblage alongside South Africa’s coast.

Our paper is revealed within the South African Journal of Science.

Leopard seal ecology

Leopard seals are apex marine predators whose habitats are normally restricted to the pack ice within the Antarctic and sub-Antarctic islands. They require pack ice to ambush their prey, the vast majority of which is made up of krill; nonetheless, they’re additionally recognized to hunt penguins, pinnipeds, fish, and cephalopods.

In trendy instances, there have been solely a handful of sightings from South Africa, each useless and alive, of leopard seals, with one of many earliest being in 1946 in East London within the Eastern Cape Province (ECP). A second sighting was remodeled 20 years later at Hout Bay in 1969.

A useless leopard seal was reported to the East London Museum (ECP) in 1994, and extra lately, a dwelling specimen was sighted at Cove Rock (ECP) in 2014. The most up-to-date sighting was in 2021, the place a dwelling particular person was noticed twice, as soon as in Cape Town and once more in Yzerfontein (Western Cape Province), earlier than sightings ceased.

Recently, we found a leopard seal tooth from a deposit relationship to the Last Glacial Maximum (LGM) (22,560–19,340 cal. BP) at WB. This makes it the primary leopard seal to be recovered from a Pleistocene and Holocene zooarchaeological assemblage alongside South Africa’s coast.

Understanding the positioning and the invention

WB is situated round 24m above the trendy shoreline subsequent to the Mlambomkulu River waterfall, ECP. It has been divided into two steady layers of sediment, particularly the Light Brown Coarse Sands (LBCS) dated to between 37,6±4,2ka and the Shell-Rich Clayey Sands (SRCS) dated by Bayesian ¹⁴C accelerator mass spectrometry mannequin from ~11ka cal BP to 10,5ka cal BP.

What makes this web site notably important is its constant proximity to the shoreline throughout each glacial and interglacial durations.

Southern Africa presently has few coastal archaeological websites relationship to the Terminal Pleistocene; though people occupied such websites on the time, many have been destroyed or stay undiscovered. This shortage is because of fixed sea-level fluctuations, which resulted in a bias in direction of preserving coastal archaeological information throughout glacial durations.

However, owing to WB’s positioning adjoining to an exceptionally slim continental shelf, it has survived and preserves information documenting repetitive human occupation spanning millennia. This web site would have been particularly fascinating to people on account of its nearness to the coast, offering marine meals and entry to a number of terrestrial assets.

It has been hypothesized that such websites would have been occupied elsewhere in southern Africa by people, similar to by the Palaeo Agulhas Plain. However, these information at the moment are underwater, making WB certainly one of just a few websites offering insights into human occupation and conduct throughout glacial and inter-glacial durations.

We report on our preliminary outcomes on faunal analyses undertaken in 2021 and their implications for the paleoenvironment at WB. Although our pattern dimension is small, the interpretations present compelling insights into native paleoenvironments and human exploitation conduct.

The paleoenvironment at WB and its implications

The web site reveals proof of a persistent mosaic surroundings in a position to help all main vegetation sorts and systematically exploiting each marine and terrestrial assets by hunter–gatherers all through.

The web site’s location and secure surroundings would have made it particularly fascinating to reside in, as hunter–gatherers would have had varied assets at their disposal whatever the surrounding surroundings.

The presence of assorted terrestrial mammals in each SRCS and LBCS layers that require completely different habitats to outlive, similar to Eland (Taurotragus oryx), duiker (Sylvicapra grimmia), and African large buffalo (Syncerus afer), point out the existence of combined, bushy and grassland environments all through the occupation of the positioning.

Additionally, the presence of fish, seals, shellfish, and doable barnacle stays within the earliest deposit (LBCS) signifies that individuals had been actively harvesting from the coast even when it was probably ~8km away throughout glacial instances. This persistent use of marine assets demonstrates the significance of coastal environments to early human communities, even in periods when the coast was additional away, and it will have probably required extra effort to journey to the coast to accumulate assets.

We recognized a leopard seal tooth from this LBCS deposit. The tooth was recognized by its distinctive triple-cusped crown, which is used for sieving krill, distinguishing it from the enamel of the extra frequent fur seal normally discovered within the area.

Leopard seals are extremely depending on the frigid waters surrounded by pack ice for his or her survival, not just for looking but in addition for breeding and meals functions. Individuals who stray too removed from their dwelling ranges are normally misplaced juveniles or ravenous and unwell.

While it’s doable that this leopard seal was one such misplaced particular person, contemplating that native sea floor temperatures had been, on common, 3°C decrease than present ranges, the situations could have been appropriate for these Antarctic predators to increase their vary northward.

The elevated pack ice ensuing from such low temperatures in northerly ranges and the reducing off of particular krill spawning websites in Antarctica could have compelled and enabled some leopard seals to happen a lot nearer to the South African coast than as we speak. Additionally, the positioning’s proximity to a river mouth would have washed inland vitamins into the ocean and will have helped preserve ocean vitamins that supported the marine animals upon which leopard seals preyed.

Considering that in these glacial instances, WB would have been round 8km from the coast, the leopard seal tooth would have needed to be introduced into the shelter by people. The presence of the leopard seal tooth indicated a a lot colder local weather and might also point out that people had been far more conversant in these animals in the course of the LGM, sufficient to acquire it and transport it, probably as sustenance to their shelter.

The procurement of all of the above animals additionally could trace at how adaptable and various the subsistence behaviors of early hunter–gatherers had been, utilizing the assets provided by predator and prey species.

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I’m a Ph.D. candidate on the University of the Witwatersrand; since 2018, I’ve been finding out archaeology with a deal with zooarcheology, rock artwork, and isotopes. My pursuits lie in uncovering the interaction between people & animals all through historical past. I search to advance present analysis on the 8.2k occasion in South Africa and contribute to filling a considerable information hole with my work. I’m actively working in direction of publishing my doctoral analysis findings & presenting my work at tutorial conferences within the hopes of turning into a well-rounded and internationally acknowledged archaeological researcher.