Thousands forced to flee their homes as much of southern Norway affected by flooding.

Thousands of people have been forced to flee their homes, and at least one person has died, in flooding which has affected much of southern Norway. The country received about three times as much rainfall as would usually be expected in the month of July, with no sign of a let-up in the first part of August. Many rivers have burst their banks, and a series of landslides have been triggered as sediments became waterlogged, impacting transport networks and other infrastructure. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. On Wednesday 9 August the Braskereidfoss Hydroelectric Dam on the Glomma River partially collapsed under the weight of water that had built up behind it, sending floodwaters across the border into Sweden. One woman is reported to have died after falling into a flooded stream on Tuesday 8 August.

Floodwaters from the Storelv River pouring through the centre of Hønefoss, to the northwest of Oslo, on 9 August 2023. Annika Byrde/NTB/Reuters.

Summer rainfall in Norway is usually driven by evaporation over the North Sea, leading to rain when westerly winds prevail, and drier spells when the wind blows from the east. However, much of this summer's rain has been driven by the exceptionally high temperatures in the Baltic Sea this July, which have led to higher rates of precipitation, and high levels of rainfall when the wind blows from the east. The average annual rainfall in Norway has risen by 18% in the past century, with much of that increase happening in the past four decades. Should high summer temperatures in the Baltic become a regular feature of a warming climate, then it is likely that Norway, and Scandinavia in general, could shift towards a much wetter climate.

Flooding at Aurdal in southeast Norway on 11 August 2023. Ole Berg-Rusten/NTB/AFP/Getty Images.

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Understanding the threat to social cohesion presented by the emergence of a warrior caste in the Nordic Bronze Age.

The emergence of a warrior caste is seen as one of the defining features of the European Bronze Age, accompanied by concepts of a warrior ideal. The precise role of such warriors within society is debatable, and likely to have varied from place to place, but it is generally accepted that a ruling warrior elite appeared in Southern Scandinavia, northern Germany, and parts of Poland and the Netherlands. However, the exact nature of this ruling class is uncertain, with centralised kingdoms, local chiefdoms, extended ruling families, and flatter societies in which one's status was entirely dependent on personal prowess have all been suggested. 

Whatever the truth of this, the widespread occurrence of Warrior Burials (individual warriors buried with weapons and other grave goods indicative of social status), buried weapons hoards, and rock art depicting the actions of warriors, all clearly send a message that these were an important group of people.

Warriors are considered to have been important figures in the trade in metals. They are known to have taken part in (sometimes lengthy) journeys by both land and sea. Moreover, the presence of items associated with personal grooming in Warrior Burials suggests that they were image conscious, and possibly felt the need to distinguish themselves from other members of the community. Such a desire to distinguish themselves may have related to the membership of an elite caste which controlled access to some forms of knowledge, possibly concerning navigation, the symbolic interpretation of rock art, or the use of weapons.

Studies of the Bronze Age societies which produced these warriors have not generally considered the impact of their activities upon those societies. Warriors are assumed to have gone to war, fought, and then returned and continued with their lives, something which seems unlikely given our knowledge of later warrior societies, and the difficulties that modern soldiers often have re-integrating into their societies after taking part in conflicts.

In a paper published in the European Journal of Archaeology on 3 August 2022, Christian Horn of the Department of Historical Studies at the University of Gothenburg, considers the threat that such warriors may have presented to their own societies, and how those communities may have dealt with that threat.

Horn considers the evidence for warfare during the Nordic Bronze Age, and considers against whom such conflicts are likely to have been fought. He then considers the impact that the presence of the warriors who fought in these wars may have had on the societies which produced them, and looks for evidence for those societies having taken steps to cope with this threat.

Warfare appears to have been a common practice during the Nordic Bronze Age. The Early Bronze Age saw the appearance of the first swords, weapons which were to become the preferred status symbol of warrior classes for the next three millennia, as well as the refinement of spears, which had been around since at least the Neolithic, as weapons of war.

Bronze weapons are less prone to corrosion than iron weapons, which has allowed the examination of many Bronze Age weapons for traces of use. This has uncovered significant evidence of these weapons being used regularly (rather than just held as status symbols), including V-shaped notches, likely to have been caused by blows from other blades, U-shaped notches, variously interpreted as being caused by impacts against axes, shields, or bone, and signs of the weapons having been regularly repaired and maintained to keep them battle-ready.

(a)–(b) Early Bronze Age spears from Torsted (Denmark, NM K B15118.19); (c) Late Bronze Age spear from Bad Oldesloh (Germany, LMSH KS923); (d) Early Bronze Age full-hilted sword from Bragby (Sweden, SHM 14759); (e) Early Bronze Age sword from Vreta Kloster (Sweden, SHM 10419:211). Horn (2022).

Evidence of violence is also fairly common in burials from the Early Bronze Age of southern Scandinavia. Examples of this include burial from Over-Vindinge in Denmark, where the skeleton of a man aged between 50 and 60 buried between 1600 and 1500 BC was found to have a broken spear tip embedded in his pelvis. Another burial site, at Kråkerøy in Norway, produced the body of a man who was suffering from malnutrition, but had apparently died as a result of several sword blows to the head and neck. Another male body showing signs of having died from sword blows to the head and arm was found on a former seafloor at Granhammar in Sweden, possibly indicating that he died in a conflict at sea in about 800 BC.

Larger scale sites are also known from the region. At Sund in Norway the bodies of 22 men, women, and children, apparently all killed in a single incident, were found. These remains all showed signs of long-term malnutrition and hard labour, making it likely that they were slaves or other low status individuals. Finally in the Tollense Valley in Germany, a battlefield site has produced 140 sets of remains to date, with roughly 5-7% showing signs of violent injuries (this does not mean that the other remains are those of people who died peacefully, as fatal injuries to soft tissue will not be preserved in skeletonised remains). Many of these injuries appeared to be old wounds, which had healed at the time of the battle, implying warriors who had taken part in more than one conflict.

Weapons, and Human remains, give a good idea about the physical effects of violence in Early Bronze Age Scandinavia, but art has the capacity to reflect how this violence was perceived and imagined by the people involved. Rock art dating to the period is widespread across Southern Scandinavia, and includes over 6000 known depictions of Human figures, as well as more than 20 000 depictions of boats. Not all aspects of life are shown in this art. Pottery and houses are never shown, and agricultural activities are known form only a few sites. 

In order to analyse the representation of violence in these images, Horn looked at a dataset of 4000 images held by the Swedish Rock Art Research Archive. Images which were damaged or unclear were excluded from the study, leaving 3742 Human figures.  Of these, 977 could be identified as male, while 32 can be identified as female. Offensive weapons were carried by 74% of the male figures, 34% of the unidentified figures, and 6% of the female figures, while defensive weapons were carried by 575 figures, 226 of which also had an offensive weapon; of these 417 could not have their sex identified, while 158 were male (i.e 16% of unidentified figures and 15% of males had defensive weapons).

A network analysis carried out by Horn found that male figures were strongly associated with exaggerated calves, swords and boats; axes, spears, and shields were also common. Female figures were also strongly associated with exaggerated with exaggerated calves and boats, but their association with swords was much lower, and other weapons absent. Long hair was also important for female figures.

Weapons are far more common in male burials than female ones in the Scandinavian Bronze Age, and violence-related injuries more frequent on male bodies, both of which suggest a male-dominated society in which social status was linked to the ability to wage war. Many pieces of rock art also depict figures in which weapons are fused with male sexual organs, apparently indicating the concept of sexual violence, and not just against women; these scenes depict both heterosexual and homosexual couplings, as well as couplings between Humans and Animals.

Scenes potentially showing sexualized violence. (a) A warrior with erect penis stabs a sexless figure with a sword or spear (Tanum 158:1); (b) Scene depicting various forms of sexual intercourse involving armed figures, and a figure with a raised spear in a fighting position (Kville 182:1). Horn (2022).

The depiction of acts of sexual violence, combined with evidence of violence against low-status individuals, makes it unlikely that these Bronze Age Scandinavian fighters were 'clean' warriors bound by some sort of noble code. Rather, these individuals appear to have been capable of using severe violence and brutality to subdue opponents. The depictions of weapons being carried and presence of weapons in burials probably indicate that the open carrying of weapons was normal, something well documented in more recent warrior-dominated societies. The widespread depictions of violence also make it likely that violence was celebrated rather than sanctioned. In such an environment it would be very easy for warriors to turn violence against weaker groups within their own society, in order to protect or bolster their own social standing.

The Battle of Tollense took place in the thirteenth century BC, a time also noted for numerous other conflicts. This has been linked to the appearance of the Urnfield Culture, which brought with it new belief systems and practices which clashed with local religions and customs. Some of the fighters from Tollense have been shown to have come from far from a long way away from the battle, suggesting they were invading outsiders. However, the much of the conflict occurring during this period still seams to have been local in nature. 

All of the fighters appearing in Bronze Age Scandinavian Rock Art are depicted in the same way, armed with similar weapons. The Vitlycke Panel at Tanum in Sweden depicts two identical warriors fighting across a boundary, shown by a row of spots. This may imply a standardised way of drawing such fighters, regardless of their actual origin or appearance, but Horn believes that is part of a body of evidence suggesting most conflict was in fact local in nature. The spear tip which killed the man at Over-Vindage was of local manufacture, and the man buried at Granhammar appears to have been killed by a local axe. The victims of the massacre at Sund were also probably killed in some local conflict, possibly linked to slaving.

Scene showing three or four warriors with similar bodies and equipment in a fight across a border depicted by a row of cupmarks at Vitlycke (Tanum 1:1). Horn (2022).

Warriors in Bronze Age Scandinavian rock art are often closely associated with boats, which again appear standardised in form, with very little variation. A scene depicting a Horse battle at Litsleby in Sweden, thought to date to the end of the Bronze Age, shows two groups of mounted warriors, again with no difference between the figures or their equipment. All of this appears to represent Scandinavian warriors fighting other Scandinavians, rather than invaders from elsewhere in Europe with different weapons and cultural items.

Fighting scenes. (a) Warriors with spears and two boats, Massleberg (Skee 614:1); (b) Warriors on horseback armed with shields and spears, Litsleby (Tanum 72:1). Horn (2022).

Warriors crossed boundaries into the territories of other groups to commit acts of violence, and used violence to defend the boundaries of their own group. Thus they were often absent from the group, and frequently tainted by death, which many societies have regarded as spiritually polluting. This can make warriors somewhat outsiders in their own communities, figures to be venerated, but also figures viewed with a degree of fear and suspicion.

The threat presented by warriors returning to their communities may also have been more tangible. A group of warriors returning from battle in a state of arousal and being treated with high kudos can present a threat to rulers even today, with plenty of modern warlords having ceased power under these circumstances. Even where local rulers were already from a warrior class, they could easily be overthrown by returning, battle-hardened young warriors with greater fighting skills or ruthlessness. If this happens repeatedly it can seriously threaten the stability of a society, something which is likely to have been a serious risk in the Nordic Bronze Age.

Furthermore, violence can be an addictive activity, particularly in societies where it is generally applauded, and when the use of violence becomes a successful political tool it can be very hard to stop. This may have been the cause of events like the massacre at Sund and the violent killing at Grenhammar. If the majority of conflicts being fought in Scandinavia at this time were local in nature, then the communities to which warriors were returning would have closely resembled the societies which they had been fighting, further undermining any social taboos against violence at home.

If returning warriors were, as Horn theorises, a threat to their own societies both spiritually and politically, then those societies can reasonably have been expected to take measures to minimise that threat, something for which he believes he has evidence.

Horn suggests that the burial of weapons, common in Scandinavia and other areas of Europe during the Bronze Age, could represent a ritual sacrifice associated with a right of passage which enabled warriors to give up their warrior status and move on to other roles in society. Such sacrifices may have involved the ritual destruction of the weapons. In Scandinavia and Northern Europe weapons burials almost always occur within 20 km of navigable waters; i.e. less than a day's walking distance. Thus potentially these burials could represent the giving up of the weapons of an entire group of warriors involved in maritime raiding.

Interpreting ritual activities from ancient sites is difficult, and requires careful excavation of the site. Many older weapons hoards in Scandinavia (and other areas) were discovered before archaeologists had an appreciation of this, resulting in a loss of information from these sites. However, some archaeologists, even in the nineteenth century, did provide careful context of their discoveries, enabling some interpretation to be made.

The Smørumøvre Hoard was excavated by Danish Archaeologist Jens Jacob Asmussen Worsaae in the 1850s. Worsaae recorded that the hoard comprised a group of bronze spearheads tightly packed together, and embedded in the floor of a former lake, possibly indicating that the had been bound into a package without their hafts before ritual deposition. The Torstead Hoard, again from Denmark, was uncovered in the 1960s, and provides better context. This hoard comprises forty spearheads and seven axeheads, deposited between 1800 and 1600 BC, within a small stone structure, which could not have held the hafts of any of these weapons. The removal of the hafts of these weapons could be a way of ritually 'killing' them by rendering them into a useless state. Some of the spears buried at Torstead also had their tips broken off, as did several swords from a hoard at Dystrup, with other swords being damaged in other ways. The Torstead Hoard was even buried in a small stone cist, similar to the ones in which Human remains were deposited at the time, re-enforcing the idea that these weapons may have been considered dead.

This ritual killing of weapons may have represented a way for warriors to shed their identities and re-integrate into their communities, something which has been recorded in some more recent societies, and proposed as an explanation for similar hoards from the Chalcolithic of Europe and Late Bronze Age of Britain.

Rock art may also have played some role in the ritual reinstatement of warriors into society. Curiously, areas where numerous hoards of Bronze Age weapons have been found tend to have very few rock paintings, while areas with large numbers of rock paintings often lack depositions of weapons, although both tend to be local to water. 

In Sweden, the majority of Bronze Age rock art is found along the stretch of coast between Bohuslän to Mälardalen, and long the large rivers of this area, and around lakes Vänern and Vättern. At Gerum a large panel depicts 95 boats, 43 figures, 28 animals, 16 footprints (some of them shod), and 187 cupmarks. The land here has been uplifting since the end of the last Ice Age, and the panel was likely completely covered by water until shortly before carving began, with carvings being made close to the water, possibly from a boat, constantly working their way down the rock face as it became exposed.

The carvings at the Berget III site in the Tyrifjorden-Randsfjorden area of Norway are also thought to have been made from a boat. This carvings are 1.7-1.8 m above sealevel today, but when they were carved would have been only slightly above the water when they were carved. This is also thought to have been true of the rock art at Flögen in Sweden, where a series of boats (and a single Bull), were depicted over the course of the Bronze Age. These are now between 11.66 and 12.51 m above sealevel, but would have been slightly above the water when made, making it likely that the artists were either in a boat or standing on frozen ice.

(a) Density of Nordic Bronze Age metalwork based on published large catalogues. (b) Density of Nordic Bronze Age rock art. Horn (2022).

All of the rock art is placed close to water, but never in sight of the open sea. Instead it is placed within straits, fjords, and bays in places it can be seen from land, but hidden from the sea, presumably indicating that the scenes were directed inwards, for the benefit of the local community, but hidden from outsiders.

In the Early Bronze Age, warriors (and others) were buried in stone barrows and cairns, where weapons and other grave goods could be easily placed. By the Late Bronze Age, however, cremation had taken over as the predominant way of disposing of the dead, severely limiting the potential for sending metal goods with the dead. In areas where rock art was common, the amount of grave goods placed in tombs was lower, and the tombs tended to be placed close to the panels, and often directly above them, possibly indicating that these could serve as a substitute for grave goods. The proximity of these tombs and art to the sea, while at the same time being hidden for it and visible to the community may have in some way been symbolic of a warrior's final journey.

Grave goods included in Warrior Burials were often diverse and numerous, including weapons, equipment for personal grooming, and decorative items. In contrast, the weapons depicted in rock art are generally very simple in their execution. Curiously, many weapons were drawn in the earliest Nordic Bronze Age were subsequently reworked and modified extensively through the remainder of the period, sometimes having Human figures added.

Once the practice of burning the dead became predominant in the Late Bronze Age, the amount of grave goods buried with the cremated dead shrank, and became less varied. At the same time the burials themselves became less conspicuous, typically on hillslopes, or as secondary burials inside existing tombs. The process began between about 1300 and 1100 BC, when detailed images of warriors began to appear in the rock art, with these detailed warriors becoming most common and elaborate between about 950 and 720 BC.

Horn interprets this as an attempt to depict a warrior ideal in art, as this medium took over from elaborate burials as the main way to remember the dead. This art may well have been used in conjunction with other rituals, and helped to convey older narratives about warriors and heroes, but this does not mean that such rituals were not also intended to help warriors find their correct place in society, or step into and out of the role of warrior when this was required. 

Nordic Bronze Age rock art appears to have been used to celebrate an ideal of maritime warriorhood. The placement of this art, at the entrance/exit to enclosed waterways, combined with a ritual link to metalworking, may suggest that this art played a role intended to help men change their roles, from fierce maritime warriors on the outside, to responsible members of the community when at home. 

The long-distance raiding abilities of early Scandinavian cultures are often considered in historical studies, but shorter raids against nearby communities would have been much more common, and no less dangerous. Furthermore, those involved in such nearby conflicts would have had far less time for any associated bloodlust to subside before returning to their home communities, making them more dangerous at home. This could have created a need for a ritual means to re-integrate these warriors into their home communities. Horn theorises that the location of the rock art, combined with the fact that this was periodically reworked, strongly implies that this art was involved in the journey-related rituals, the most likely of which to need a ritual intervention were war raids.

The ritual sacrifice of weapons, combined with the retelling and embellishment of local warrior legends, performed at the boundaries of communities and the outside world, could have been a way for men to keep their identities as warriors in the outside world separate from their roles within their home community, thereby reducing the danger of internal conflicts within small communities.

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Residents evacuated after landslide hits village in Viken County, Norway.

Ten people have been injured, one of them seriously, and another eleven are missing after a landslide hit the village of Gjerdrum in Viken County, southern Norway, at about 4.00 am local time on Wednesday 30 December 2020. Several houses are reported to have been buried under mud and debris in the village, with others sliding into the hole created by the landslip, and about 900 people have been evacuated amid concerns about further landslips.

 

A landslide in the village of Gjerdrum in Viken County, southern Norway, on 30 December 2020. 30 December 2020. BBC.

The landslide is thought to have been of a type known as a 'quick clay' landslip, in which an entire bedding plain of clay loses its cohesion at once, and flows like a liquid, a type of landslide largely peculiar to areas of heavy Pleistocene glaciation, such as the northern coasts of Scandinavia, Russia, Alaska and Canada. Quick clay deposits were laid down in areas where the land was pushed down beneath sealevel by the weight of glaciers, and has subsequently been uplifted after the glaciers retreated. These clays typically contain far higher salt contents than other marine clays, which can be washed out by rainfall. Significantly, they generally contain significant levels of positively charged sodium cations, which entered the clay as the sea above froze, and help to bond the negatively charged clay particles together. However, sodium particles are particularly soluble in water, and easily washed out, with the effect that once a certain level of sodium has been lost, the entire bedding plane loses its cohesion.

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Dutch citizen killed by Polar Bear on Spitsbergen Island, Norway.

A Dutch citizen has died after being attacked by a Polar Bear, Ursus maritimus, on Spitsbergen Island in Norway's Svalbard Archipelago. Johan Jacobus Kootte, 38, was sleeping in a tent on a campsite near the island's main settlemens of Longyearbyen, when he was attacked at about 3.50 an on Friday 28 August 2020. The Bear was shot by a local resident, and subsequently found close to the island's airport. Mr Koote was pronounced dead upon arrival at a local hospital. He is understood to have been working as a manager at the site, which is owned by a friend. Many people on Spitsbergen Island have subsequently questioned the positioning of the campsite, which is close to a shore known to be utilised by Polar Bears. The site was protected by an electric fence, but does not appear to have had other anti-Bear defences.

 

Dutch citizen Johan Jacobus Kootte, 38, who was killed by a Polar Bear on Spitsbergen Island, Norway, on 28 August 2020. Svalbard Posten.

Polar Bears are considered to be Vulnerable under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species, and are a protected species in Norway, where it is only legal to shoot them in self defence. Bears which approach too close to Human settlements are typically shot with tranquiliser darts, and then relocated to more remote areas, with two Bears, a mother and cub, having been relocated from close to Longyearbyen earlier this week.

 

The remains of the tent in which Mr Kootte was sleeping at the time of the attack. Svalbard Posten.

Although Polar Bears are considered to be potentially very dangerous, attacks on Humans are relatively rare. There have been five fatal attacks in the Svalbard Archipelago in the past 50 years, the most recent in 2011, when English student Horatio Chapple, 17, was killed in an attack in which several other students were injured. There has been one other Bear-attack recorded in the past decade, when a Czech tourist was attacked at a campsite in 2015, although on that occasion the Bear was driven off before killing its victim.

 

A Polar Bear, Ursus maritimus. Alan Wilson/International Union for the Conservation of Nature/Red List of Threatened Species.

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Lodgers on the tubes of Tube Anemones.

Benthic organisms are well adapted to the habitat conditions present in the locations where they live and estimates of abundance of these organisms are usually related to the habitat in which they are found. Moreover, some species require anchoring sites to settle and complete part of or their whole life cycles. Thus, the lack of consolidated structures on unconsolidated bottoms leads many benthic settlers to seek different suitable substrates, amongst which are artificial substrates such as ship hulls or offshore platforms, and natural substrates, such as marine invertebrate shells, Corals, and Ceriantharian (Tube Anemone) tubes. Ceriantharians (Cnidaria: Anthozoa) are tube-dwelling Animals that synthesize their tubes primarily with the use of ptychocysts, a type of cnida only found in this group, combined with small sediment fragments from the sea bottoms where the tube is built. The soft texture of ceriantharian tubes would initially appear not to be an attractive feature for the anchoring of invertebrate species that usually use rigid structures as anchoring locations. However, a few studies have reported on species able to settle on this microhabitat. In spite of it, the sampling of Ceriantharia is rather troublesome and rare, and tubes are usually overlooked and rarely collected along with polyps, contributing to lack of information about this subject.

In a paper published in the journal Biodiversity Data on 8 January 2020, Hellen Ceriello and Celine Lopes of the Instituto de Biociências at the Universidade Estadual Paulista, James Davis Reimer of the University of the Ryukyus, Torkild Bakken of the University Museum at the Norwegian University of Science and Technology, Marcelo Fukuda of the Museu de Zoologia da Universidade de São Paulo, Carlo Magenta Cunha of the Universidade Federal de São Paulo, and Sérgio Stampar, also of the Instituto de Biociências at the Universidade Estadual Paulista report on invertebrate communities inhabiting tubes of different Ceriantharian species from different locations, and discusses their main characteristics.

Ceriello et al. sampled 22 tubes of 10 species of Ceriantharia by SCUBA surveys in Argentina, Brazil, Japan, Norway, Portugal, and the United States. All material, except for Isarachnanthus nocturnus, and Ceriantheomorphe sp., was preserved along with their polyps and, before analyses, all polyps were removed from their tubes which were kept individually in labelled jars containing 70% ethanol.

The Tube Anemone, Isarachnanthus nocturnus.  Sergio Stampar/National Science Foundation.

Each tube was analyzed separately under a stereomicroscope in a bowl with dark craft foam in the bottom and full of freshwater. All tubes were longitudinally cut with surgical carbon steel scalpels, opened, and fixed in the craft foam using acupuncture needles. Both inner and outer walls were analysed. The fauna found in or on the tubes was removed, photographed, and measured using a Zeiss AxioCam MRc5 and Zeiss AxioVision SE64 Rel 4.8 imaging software. Afterwards, the associated fauna was morphologically identified with specific taxonomic keys for each group.

A total of 58 species (8 crustaceans, 24 molluscs, 26 polychaetes) was observed in/on ceriantharian tubes. It is noteworthy that, although Crustaceans and Polychaetes in this study were alive at the time of sampling, they were not alive during tube analyzes. The results were separated by taxonomic group.

Thirghty eight Mollusc shell specimens, including Gastropoda and Bivalvia, were observed and were always found adhered to the outside of the tubes, and none had a periostracum coating, indicating that they were not alive at the time of collection.

Mollusca found on Ceriantharian tubes. (A) Schwartziella bryerea (B) Parvanachis obesa (C) Bittiolum varium (D) Cerithidea balteata (E) Chrysallida sp. (F) Liotella sp. (G) Emarginula sp. (H) Bostrycapulus odites (I) Collonista rubricincta (J) Eulima sp. (K) Microgaza rotella (L) Turbonilla sp. (M) Caecum regulare (N) Puncturella noachina (O) Basterotia elliptica (P) Ervilia nitens (Q) Macomopsis melo (R) Cumingia lamellosa (S) Musculus lateralis (T) Cardites micellus (U) Tivela sp. (V) Sphenia fragilis. Scale bars (A)-(N) 500 μm (O)–(U) 500 μm (V) 100 μm. Ceriello et al. (2020).

Ceriello et al.observed shells of Schwartziella bryerea and Turbonilla sp. adhered to the fragile tube of Arachnanthus sp., as well as amongst sediments that surrounded the tube. Shells of Cerithidea balteata, Eulima sp., Liotella sp., Emarginula sp., Chrysallida sp. and Collonista rubricincta, were found attached to the entire length of the thin and delicate tube of Isarachnanthus bandanensis. Bittiolum varium was found attached to the tubes of Isarachnanthus nocturnus. Puncturella noachins was, in part, adhered to the thin and fragile tube of Cerianthus lloydii.

On the tubes of Ceriantheomorphe brasiliensis, Ceriello et al. noted shells of Bittiolum varium, Finella dubia, Parvanachis obesa, Bostrycapulus odites, Caecum regulare, and Microgaza rotella. The tubes of Ceriantheomorphe brasiliensis usually have a high amount of overlap of filaments and, although this pattern was also observed in specimens in this study, no Mollusc shells were found between layers, and shells were only found on the outermost surfaces of the tubes.

Shells of Ervilia nitens, Chama sp., Cardites micellus, and Tivela sp. were observed adhered on the tube of Arachnanthus sp., while Ervilia nitens, Basterotia elliptica, and Musculus lateralis, were observed adhered on the tubes of Isarachnanthus nocturnus.

Shells of Sphenia fragilis, Ervilia nitens and Musculus lateralis were observed upon the tubes of Ceriantheomorphe brasiliensis, and shells of Macomopsis melo, were observed covering considerable areas of the tube of Ceriantheomorphe sp.

The only area on the tube of Ceriantheopsis americana where Ceriello et al. observed the presence of Mollusc shells, was on its slender end that was vertically inserted into the soft bottom. All specimens observed were Cumingia lamellosa, and these were found in high amounts and firmly attached to the tube.

Ceriello et al. observed 29 Peracaridans, belonging to 8 families, including 5 Amphipod species, 2 Isopod species and 1 Tanaidacean species on the tubes of three Ceriantharian species.

Crustacea and Polychaeta found in/on Ceriantharian tubes. (A) Monocorophium acherusicum (B) Idotea balthica (C) Cymadusa filosa (D) Paranthura urochroma (E) Photis sarae, female and male, respectively (F) Ampelisca burkei (G) Chondrochelia savignyi (H) Elasmopus pectenicrus (I) Nereis sp. (J) Phyllodocidae, indet. (K) Cirriformia sp. (L) Sternaspis sp. Scale bars: (A)-(H) 1000 μm (I) 2000 μm (J) 600 μm (K) 1000 μm (L) 3000 μm. Ceriello et al. (2020).

Most peracaridans were found in areas far from the Ceriantharian tentacles, thus not easily accessible to the Ceriantharian. No specimen was found inside the tubes or amongst tube layers. On the tubes of Ceriantheomorphe brasiliensis, Ceriello et al. observed the Amphipods Ampelisca burkei, Cymadusa filosa, Elasmopus pectenicrus, and Photis sarae, and the Isopod Paranthura urochroma firmly attached to the tube external wall; both Amphipods and Isopods were surrounded by ptychocyst filaments. Additionally, Ceriello et al. found Tanaidaceans of species Chondrochelia savignyi; however, those were free from ptychocyst filaments and were not firmly attached. Monocorophium acherusicum (Amphipoda) and Idotea balthica (Isopoda) were also found surrounded by ptychocyst filaments and attached to the external wall of the tube of Ceriantheopsis lineata. One specimen of Photis sarae was noted amongst Algae thalli covering the tube of Isarachnanthus nocturnus. It is noteworthy that the amphipod was not directly attached to the tube, but instead it was freely on its surface.

A total of 122 Polychaetes, including 17 families and 26 species, were found in or on tubes of six species of Ceriantharia. Some of the specimens were not possible to identify further than family or genus, as they were fragmented or in poor condition.

Ceriello et al. observed one specimen of Lysilla loveni (Terebellidae), two Cirratulids, two Paraonids and two Syllids in between layers of the tube of Botrucnidifer norvegicus. On the external wall of the tube of Ceriantheomorphe brasiliensis, Ceriello et al.found Cirratulids (Cirriformia spp.), Eunicids (Lysidice spp.), nereidids (Neanthes sp.), Syllids (Exogone spp., Myrianida sp. and Syllis prolifera), and Spionids (Aonides sp. and Dipolydora spp.), and one specimen each of Sabellidae (Branchiomma sp.), Flabelligeridae (Brada sp.), Magelonidae (Magelona sp.), Polynoidae (Malmgreniella sp.), Capitellidae (Mediomastus spp.), and Phyllodocidae. Only some specimens had ptychocyst filaments surrounding them and keeping them firmly attached to the tube. Ceriello et al. observed Dipolydora spp. amongst Algae thalli covering this tube, as well as in between folds of layers of the tube of Ceriantheomorphe brasiliensis from Guanabara Bay.

The heavy tubes of Ceriantheopsis lineata showed many perforations that were occupied by either deeply or superficially burrowed Polychaetes between some layers. Beneath layers, we observed some Spionids (Dipolydora spp.) and single specimens of Capitellid (Mediomastus spp.), Cirratulid (Cirriformia spp.), and Oenonid (Notocirrus spp.). The removal of layers also revealed empty boring holes under them. Moreover, Ceriello et al. found Syllis garciai (Syllidae) and one Phyllodocid on the tube surface, surrounded by ptychocyst filaments and mucus, respectively.

Some Parasabella sp., Lysidice spp., Cirriformia spp., and Spirobranchus sp. were found amongst algae thalli partially covering one of the tubes of Isarachnanthus nocturnus. However, they were not attached to the tube and neither had ptychocyst filaments surrounding them. Additionally, Ceriello et al. observed Notocirrus spp. on the surface of this tube.

Ceriello et al. observed one maldanid on the surface of the tube of Ceriantheomorphe sp., as well as large Nereis sp. partially burrowed, and small groups of Sternaspis sp. (3 specimens each group) both superficially anchored and deeply burrowed into tube layers.

Finally, Ceriello et al. found 36 Notocirrus spp. and two syllids on tubes of Pachycerianthus schlenzae, either burrowed between layers or attached to the surface of the tubes. In both cases, there were some specimens coated by their own mucus, but none was firmly attached to the tubes.

There have been some previous studies on the presence of marine invertebrates anchored on Ceriantharian tubes, with results suggesting that they are a suitable option as a consolidated structure for the settlement in unconsolidated bottoms. Ceriello et al.'s results not only corroborate the use of ceriantharian tubes as alternative substrates for other organisms, but also indicate a different anchoring method for species of the three phyla evaluated, Mollusca, Arthropoda (Crustacea) and Annelida (Polychaeta). Furthermore, they suggest possible benefits acquired by species on Ceriantharian tubes, discuss the use of mollusc shells in ceriantharian tube construction, and report new location records for six taxa.

Ceriello et al. did not observe whether Peracaridans and Polychaetes voluntarily settle on Ceriantharian tubes or are incorporated into the tubes by the Ceriantharians. In spite of this, their results show that most of these specimens were found in areas of the tubes where the tentacles of the Ceriantharian could not easily reach them. Thus, it is most likely that these species have actively recruited this alternative substrate than have been incorporated into it by the actions of the Ceriantharian. As Ceriello et al. could not evaluate this possibility, this hypothesis cannot be excluded.

Ptychocyst filaments are the most common material in Ceriantharian tubes. Notably, most Amphipods and Isopods firmly anchored to Ceriantharian tubes were surrounded by filaments (e.g. Ampelisca burkei, Cymadusa filosa, Idotea balthica, Monocorophium acherusicum, Paranthura urochroma, and Photis sarae), while some other specimens, such as Chondrochelia savignyi, were not. Likewise, some Polychaetes were observed surrounded by filaments (e.g. Syllis garciai) and thus firmly anchored, while others were coated by their own mucus (e.g. Phyllodocids and Notocirrus spp.) and only superficially anchored. It has been suggested that ptychocyst filaments have adhesive properties and our observations support this suggestion, as it is likely that the adhesive property of ptychocyst filaments is used by Peracaridans and Polychaetes as an anchoring method to settle on Ceriantharian tubes. Otherwise, specimens not surrounded by ptychocyst filaments must have alternative anchoring methods to keep them on tubes.

Crustaceans, Tubeworms and Ceriantharians often acquire shelter against predators in self-built-tubes which may be rigid, as in some Cirratulids, Sabellids and Serpulids. Ceriello et al. observed the Polychaetes Lysidice spp. anchored on Ceriantharian tubes. As members of this genus commonly excavate galleries or temporarily occupy empty galleries/tubes of other organisms, it is possible that Lysidice spp. use Ceriantharian tubes as alternative habitats.

Tube-dwelling Amphipods, Isopods, and Tanaidaceans usually burrow directly into the soft bottom, forming mucous tubes for habitation. For instance, the Amphipod Photis sarae was observed anchored on tubes of Isarachnanthus nocturnus and Ceriantheomorphe brasiliensis. However, this species is usually found in soft tubes built with mucus, small sediments and, sometimes, living organisms (e.g. Algae), similar to Ceriantharia. Ceriello et al. also observed other tube-dwelling Peracaridans coated by ptychocyst filaments and attached to the surface of Ceriantharian tubes, suggesting that, by using Ceriantharian tubes, Peracaridans can be sheltered, without the necessity of building their own tubes.

Mollusc shells were observed on all Ceriantharian tubes examined. However, the absence of periostracum coating these shells suggests that Ceriantharians do not shelter living Molluscs, but instead they adhere empty shells to their tubes, using them as a relevant component for the tube construction. The addition of Mollusc shells and other sediment remains as tube constituents may reinforce the tube, increasing its resistance and, thus, having an architectural role. Moreover, the external surfaces of all shells were usually very worn, indicating that they were part of the seafloor sediment rather than part of living assemblages. Although Ceriello et al.'s data do not allow them to assess how the shells were obtained during tube construction, future studies would be useful to provide such information (e.g. is there any special behavior associated with inclusion of Mollusc shells?) and to examine if it is possible that Ceriantharian tubes shelter living Molluscs.

It has been suggested that empty Mollusc shells enable the understanding of biodiversity patterns of Mollusca fauna at a specific site and can thus be used to provide data on ecological and evolutionary timescales. Accordingly, a similar role could be attributed to the accumulation of shells in Ceriantharian tubes, reflecting the species richness of living Molluscs in the surrounding habitat.

This is the first record of Microgaza rotella (Mollusca) and Brada sp. (Polychaeta) in Laje de Santos, and Photis sarae (Peracarida) in São Sebastião and Laje de Santos, São Paulo State, in southeastern Brazil. To date, Microgaza rotella had been reported as occurring from the southeastern United States to northern Brazil, and, since that there have been no other records in literature regarding this species in southeastern Brazil Microgaza rotella may occur naturally at this location (Laje de Santos) and may be rare or allochthonous (i.e. originated in a region other than where it was found) and transported by other species. Brada had been previously reported in Brazil only from Ubatuba City, while Photis sarae had only been previously reported in Rio de Janeiro State.

This is also the first record of Dipolydora in Rio de Janeiro State, and Notocirrus spp. and Syllis garciai in Espírito Santo State. Dipolydora had only been previously reported from Brazil in São Paulo, Paraná and Espírito Santo States. Notocirrus had been reported occurring in São Paulo, Rio de Janeiro, Paraná and Bahia States, while Syllis garciai had only been previously reported in São Paulo State.

It is noteworthy that Lysilla loveni (Polychaeta) was found on the tube of a Nordic Ceriantharia species, Botrucnidifer norvegicus. This Polychaete species has only rarely been found and usually as single occurrences scattered along the Norwegian coast.

Biogenic structures, such as Ceriantharian tubes, play a major role in altering community structure, thus affecting species richness and individual abundances. Tubes may affect the stability of the sea bottom and provide refugia from predation, as well as surfaces for the recruitment of benthic organisms. In fact, species abundance and richness have been observed to be greater around or on tubes than in areas without tubes. Ceriello et al. did not compare the fauna from Ceriantharian tubes to that from the surrounding sea bottoms however, their results demonstrate that Ceriantharian tubes appear to be suitable alternative substrates for numerous species, especially tubicolous and infaunal invertebrates that usually spend much energy burrowing into sediments or anchoring on fixed or mobile habitats while seeking shelter. Moreover, other than shelter, residents on and in Ceriantharian tubes may also acquire protection. Therefore, the tubes of Ceriantharia may play an important role as small-scale biodiversity hotspots.

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Houses swept away by landslide in Norway.

A landslide at Kråknes in Finnmark County, northern Norway, has swept a cluster of houses into the sea. The incident happened at about 4.00 pm local rime on Wednesday 3 June 2020, when a section of land 600 m wide and 150 m deep shifted downslope abruptly, carrying with it eight houses. The land remained reasonably intact for most of the slip, but broke up as it came to the top of the beach below, destroying the structures upon it. The majority of the buildings were unoccupied at the time of the incident, as they were holiday homes only occupied at the weekends at this time of year, though one person had to be rescued by helicopter.

Landslide at Kråknes in Finnmark County, northern Norway, on 3 June 2020. Around Zeeworld/YouTube.

The landslide is thought to have been of a type known as a 'quick clay' landslip, in which an entire bedding plain of clay loses its cohesion at once, and flows like a liquid, a type of landslide largely peculiar to areas of heavy Pleistocene glaciation, such as the northern coasts of Scandinavia, Russia, Alaska and Canada. Quick clay deposits were laid down in areas where the land was pushed down beneath sealevel by the weight of glaciers, and has subsequently been uplifted after the glaciers retreated. These clays typically contain far higher salt contents than other marine clays, which can be washed out by rainfall. Significantly, they generally contain significant levels of positively charged sodium cations, which entered the clay as the sea above froze, and help to bond the negatively charged clay particles together. However, sodium particles are particularly soluble in water, and easily washed out, with the effect that once a certain level of sodium has been lost, the entire bedding plane loses its cohesion.

 The aftermath of the 3 June 2020 Kråknes landslide. The Weather Channel.

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