bluuebunny/crossref_metadata_2025 huggingface dataset:
A Feudal Way to Gentrify? The Modern Concept of Gentrification Versus Changes in the Social Topography of a Medieval and Early Modern Town
Authors: Thomasson Joakim
Published: June 2021

Gentrification is a current and often debated concept that concerns social changes in our cities. The concept relates to a development whereby areas earlier inhabited by less wealthy social groups are taken over by middle and upper middle-class residents. In the discussions of these changes, two perspectives have dominated. Representatives for the consumer perspective argue that gentrification occurs as a result of consumption preferences in the middle class. Representatives of the producer perspective argue that inner city areas are gentrified as a result of the movement of capital. In the article it is discussed whether it is possible to use the concept of gentrification, and ifthe conflicting perspectives can be tested, in a non-capitalistic setting. The case-study focuses on the changes in the social topography of the town of Malmö, at the time the second largest town in Denmark. The main issues investigated are whether these changes were produced within the feudal structures, how consumer preferences and agency interacted, and the relations between agency and structural constraints.
White Light —White Heat: The use of Fire as a Light and Heat Source in an Atrium House in Roman Pompeii
Authors: Boman Henrik
Published: June 2021

This article concerns the distribution of fire as light and heat source within the insula investigated by the ongoing Swedish Pompeii Project. Here the author suggests that fire installations as kitchens, ovens and baths were clustered in specific areas within this insula, and the installations were not efficiently used to heat the dwelling areas of the house. It is also proposed that the surfaces of the interior walls and floors of the Roman atrium house were polished in purpose to reflect and distribute light and, which is emphasised in the article, to soften the transition between brightly lit areas and areas in dark shadow. This contrast had to be eliminated for the human eye to adopt to the light conditions in the room and by that, to make the light as efficient as possible.
When Was Westerhus Churchyard in Use?
Authors: Siven Claes-Henric
Published: June 2021

The period of use for the Swedish medieval churchyard of Westerhus has been estimated by the maximum likelihood method. Raw data consist of 30 calibrated '4C-dates of some of the skeletons from the site. Bias and other properties of the maximum likelihood estimator are analyzed via a number of Monte Carlo simulations. The point estimates imply that the site was used in the period 1073-1356, that is, a somewhat longer period than previously assumed. The estimated length of the period of use affects the interpretation ofthe great number ofburied children. Population calculations lead to the conclusion that the six agglomerations of children's graves cannot be interpreted as mass graves.
Vikings, Rus, Varangians: The "Varangian Problem" in View of Ethnicity in Archaeology
Authors: Hillerdal Charlotta
Published: June 2021

The Scandinavian activity in Russia during the Viking Age has left traces in both the archaeological and the written material. In the 13th century Russian annals, "The Primary Chronicle", a story is told ofhow "Varangians from beyond the sea" founded the first Russian realm. The Varangians have been interpreted as Scandinavians, and the archaeological material has been connected with this story. This has resulted in a scientific debate, which in many cases has been steered by nationalistic feelings and political aims.
Borderland-stalkers and Stalking-horses Horse Sacrifice as Liminal Activity in the Early Iron Age
Authors: Monikander Anne
Published: June 2021

This paper investigates the fact that many Early Iron Age wetland sacrifices were deliberately placed in liminal zones. The sacrifice of horses as well as the manipulation of their heads, hoofs and tails turned them into liminal creatures. In this way they imitated the liminal creature, in particular the Midgard Serpent that bites its tail in the ocean surrounding the world, and the horses also became guards against dangerous powers from outside Midgardr. The attention to tongues can also be seen on the bracteates that may have served as amulets, reminding their users ofthe creatures guarding the borderlands.
Capitalism in Central Norrland, Sweden, during the Iron Age
Authors: Von Stedingt Henrik , Baudou Evert
Published: June 2021

The authors challenge the opinion that a traditional hunter-gatherer culture existed during the Iron Age in the forested interior of central Norrland (En. Northern Sweden). Two new and several earlier pollen analyses together with osteological finds from domestic animals confirm that extensive forest grazing was widespread throughout the interior. The distribution of iron slag deposits suggests that iron production is a key factor to understanding the society in the area. The modes of subsistence, the low-technology ironwork, and a common conceptual world as reflected in the graves on the coast and in the interior can be viewed as elements of an early capitalistic system.
Imaginary Vessels in the Late Bronze Age of Gotland and South Scandinavia: Ship Settings, Rock Carvings and Decorated Metalwork
Authors: Bradley Richard , Skoglund Peter , Wehlin Joakim
Published: June 2021

The paper compares the Bronze Age ship settings of Gotland with the vessels portrayed in rock carvings on the Scandinavian mainland. It also makes comparisons with the drawings of vessels on decorated metalwork of the same period. It considers their interpretation in relation to two approaches taken to the depictions of ships in other media. One concerns the use of boats to transport the sun, while the other emphasises the close relationship between seagoing vessels and the dead. A third possibility concerns the distinctive organisation of prehistoric communities on Gotland. It seems possible that the largest of the ship settings were equivalent to the Bronze Age cult houses found on the mainland and that they may even have represented the island itself.
The Divine Appearance 0f Härn: Determining the Identity of a Bronze Age Metal Hoard
Authors: Forsgren Magdalena
Published: June 2021

This article aims to investigate the mysterious divinity Härn on the basis of a Bronze Age metal hoard from Härnevi in Uppland. The premise is that this hoard rep- resents a cultural category that reflects a divine concept that must be investigated in order to understand the meaning behind the deposition. Through mythological parallels, Härn’s characteristics will be explored as well as the relation between the sun and fertility across time and space. It is suggested that Härn originally was a sun goddess emanating from the Bronze Age and related to the Norse goddesses Njärd and Freyja.
The Art of Valuating a Heritage: From a Swedish Management Perspective with Past and Present Example
Authors: Jensen Ola W.
Published: June 2021

To identify what ought to be protected and why is one of the most important missions of the heritage manage- ment. Issues related to values and the act of assessing are, however, seldom scrutinized on a deeper level. The aim of this article is to give a short history of the valu- ation of the heritage up to the present from a Swedish perspective. Additional aims are to reveal some current and historical trends in order to illustrate the connection between past and present valuation systems, to analyze various issues that have contributed to the current plu- ralistic approach, and to investigate which theories of values affect our assessments today.
Veitstu hvé blóta skal? The Old Norse blót in the Light of Osteological Remains from Frösö Church, Jämtland, Sweden
Authors: Magnell Ola , Iregren Elisabeth
Published: June 2021

The osteological remains from Frösö Church, Jämtland, have been re-analysed in order to understand the Viking Age rituals at the site and to study the blót, the Old Norse sacrifice and feast. Radiocarbon analyses of ani- mal and human bones date the rituals to the late Viking Age. A taphonomic study shows that especially brown bear and pig were of importance in the rituals. Butcher- ing marks reveal the processing of the carcasses as well as feasting. Further, bones and not whole carcasses seem to have been deposited on the ground. Human remains have been treated differently from the animal bones and may represent disturbed burials rather than sacrifices. Seasonal analysis indicates that the rituals took place in late autumn, early spring, and possibly around the summer solstice. The results of the osteological analy- ses are also discussed in relation to the written sources about the Old Norse blót.
The Marvel of Cauldrons: A Reflection on the United Stories of Archaeology
Authors: Hegardt Johan
Published: June 2021

Archaeology and heritage, in whatever form, can be understood today as either the past that should be managed as something outside the present and by pro- fessionals who shape a master narrative, or as some- thing present and open to a diversity of interpretations and narrations in the present. In this text I will exam- ine the consequences of both these perspectives and end with the conclusion that it is a question of ontolog- ical care, the kind of care which, by means of a criti- cal narrative, must be open to all the stories involved.
To be Buried Inside a Long-Forgotten World: Studying the Reuse of Passage Graves Wearing “Bronze Age Glasses”
Authors: Wollentz Gustav
Published: June 2021

The theories presented about the reuse of Neolithic monuments during the Bronze Age in Scandinavia are mainly universal, i.e. applicable to all periods during prehistory. I argue that there is no point in isolating reuse as something separate from society. The focus of my study is the Mysinge passage grave on the is- land of Öland. I have also studied the reuse of other graves on Öland and of passage graves in Falbygden. I propose that the passage grave was linked to the un- derworld and that some of those buried in the cham- ber of Mysinge during the Bronze Age were people travelling by sea.
The Indian behind the Artefact or Things behind the Process?: Humanism, Post-humanism and the Transition to the Neolithic
Authors: Garcia-Rovira Irene
Published: June 2021

In recent years, traditional models produced to ac- count for the transition to the Neolithic have been challenged with the creation of narratives that seek to portray the character of this change in specific socio- historical milieus. At the other end of the spectrum, approaches influenced by the material turn have read- dressed this context, defining the Neolithic as a spe- cific horizon within an ever-increasing entanglement. Whilst these interpretive frameworks have yet not been challenged, they might gradually give rise to a new polarization in the debate about the Mesolithic- Neolithic transition. These approaches differ not only in that they operate at different scales of analysis (lived experience, macro-scale). They ultimately echo the humanist/post-humanist debate currently held in theoretical archaeology.

In this article, I argue that neither of these ap- proaches is successful in revealing the complex set of forces that triggered the transition to the Neolithic. Drawing from this discussion, I suggest that a more comprehensive review of this context of change re- quires the fusion of elements discussed by these mod- els. This situation hastens new challenges to archaeo- logical practice, and it raises a series of questions on the current state of archaeological theory.
Harm’s Way: An Approach to Change and Continuity in Prehistoric Combat
Authors: Horn Christian
Published: June 2021

Warfare has been recognized as an important factor in past societies, but the way it contributes to change is still not very well understood. When it comes to an- cient war, archaeology faces a problem: we are rarely able to address the intentions behind wars. This article seeks to take a look at the micro-scale of warfare and address what, and how, it contributed to change. To achieve this it was necessary to take a close-up look at combat, weapons and fighters as elementary parts of warfare. The use-wear analysis of 208 Early Nor- dic Bronze Age spears and swords, and 15 Late Neo- lithic halberds will be used as a case study to address several problems: 1. the (non-) functionality of early weaponry; 2. the conduct of combat; 3. the relation between weapons, fighters and combat. A hypothesis will be formulated in order to understand combat in terms of communication as a mediator between dif- ferent agents of warfare.
Nature:Cultures – Heritage, Sustainability and Feminist Posthumanism
Authors: Fredengren Christina
Published: June 2021

This paper makes use of feminist posthumanism to outline how a range of heritage policies, practices and strategies, partly through their base in social constructivism have a clear anthropocentric focus. Not only do they risk downplaying materiality, but also a number of human and non-human others, driving a wedge between nature and culture. This may in turn be an obstacle for the use of heritage in sustainable development as it deals with range of naturalized others as if they have no agency and leaves the stage open for appropriation and exploi- tation. This paper probes into what heritage could be in the wake of current climate and environmental challenges if approached differently. It explores how a selection of feminist posthumanisms challenge the distinction between nature:culture in a way that could shift the approach to sustainability in heritage making from a negative to an affirmative framing.
Tangible Traces 0f Devotion: The Post-mortem Life of Relics
Authors: Kjellström Anna
Published: June 2021

Though relics have attracted immense interest from a variety of scholars, not much attention has been paid to the practical handling of the holy corporal remains. Here, with the aim of better understand- ing the treatment of the bodies and relics as physical objects in Sweden during the Middle Ages, osseous materials from three different contexts were osteo- logically analysed. The investigation offers detailed insight into the treatment of the bones and makes it possible to distinguish three physical phases of the cult of relics. The three phases demonstrate the utilitarian administration of the bones and the for- titude of belief.
Prehistoric Violence as Difficult Heritage: Sandby Borg – A Place of Avoidance and Belonging
Authors: Wollentz Gustav
Published: June 2021

Despite an increased focus on heritage connected to violence within archaeological research projects, there has been no proper focus on the rediscovery of prehistoric massacres, from the perspective of diffi- cult heritage. Most likely, the temporal distance in- volved has led to the assumption that such research is superfluous. The ongoing excavations of an Iron Age massacre in the ring fort of Sandby Borg, on Öland, Sweden, challenges the validity of such an a priori assumption. This paper focuses on Sandby Borg through interviews conducted with the local population who grew up near the ring fort. The interviews reveal how new narratives and relations to the past have been created through the discovery. The results call for us to move away from a linear and chronological understanding of difficult heri- tage, in which time is approached as gradually ‘purifying’ difficult heritage, towards understand- ing ‘dissonance’ as inherent in each site of heritage, which can be used as a resource.
Going from Analogue to Digital: A Study of Documentation Methods during an Excavation of the Neolithic Flint Mines at Pilbladet, Sweden
Authors: Berggren Åsa Ottosson , Gutehall Anders
Published: June 2021

The ‘digital turn’ in archaeology has resulted in documentation, analysis, visualization and repository requirements becoming increasingly digital in recent years. However, we are only at the beginning of understanding how the shift from analogue to digital affects archaeological interpretation, as attention has mainly been directed towards technological aspects. However, how archaeology is executed influences the production of archaeological knowledge, and additional research into digital practices and their consequences is needed. During the latest excavation in 2014 of the Neolithic flint mines of Södra Sallerup, in Malmö in southern Sweden, several recording methods were used to document the remains in plan, including hand drawing, digital mapping with GPS and digital photography using a camera mounted on a pole. The records were used to create both a digital plan as well as georeferenced orthophotos from a 3D model and from photomosaic. The aim was to produce a record comparable to previous documentation from decades of archaeological excavations of the flint mines in the area, as well as one that is up-to-date with today’s digital standards. The methods are described and their consequences for the archaeological results are discussed.
Pandemi Covid 19, Stabilitas Keamanan, Daya Beli Masyarakat dan Pertumbuhan Ekonomi Nasional
Authors: Editorial Tim
Published: June 2021

Konsep keamanan mengalami pergeseran isu-isu keamanan tradisional menuju pada isu keamanan non-tradisional terutama pada people oriented yang berkembang menjadi multidimensional seperti ekonomi, sosial dan lingkungan yang berkaitan dan tidak terpisahkan satu sama lain (Buzan, 1991:433). Barry Buzan menyatakan terdapat lima dimensi yang saling terkait, yakni : military, political, economic, societal dan environmental.
Role of Grafting in Tolerance to Salt Stress in Melon (Cucumis melo L.) Plants: Ion regulation and antioxidant defense systems
Authors: KUŞVURAN Şebnem , KAYA Elif , ELLİALTIOĞLU Ş. Şebnem
Published: June 2021

Grafting in vegetables is a method that has been commonly used in recent years, not just for the treatment of soil borne diseases and pests, but also to facilitate higher abiotic stress tolerance under conditions such as salinity. Herein, it was aimed to determine if the salt tolerance of two salt-susceptible melon genotypes, SCP-1 and SCP-2, could be improved by grafting onto TLR-1 and TLR-2, which are salt-tolerant melon genotypes, and Albatros commercial melon rootstock. The grafted plants were grown in plastic pots containing a peat: perlite mixture and exposed to NaCl at doses of 0 and 200 mM under greenhouse conditions. The salt-tolerant rootstock significantly diminished the damaging effects caused by salt stress via a reduction in the uptake of Na and Cl, which enhanced Ca and K uptake and micronutrition. Stress- induced activities of catalase, superoxide dismutase, ascorbate peroxidase, and glutathione reductase were considerably higher in the grafted plants. The results showed that grafting salt susceptible plants onto the salt-tolerant rootstock improved the growth regulation. The salt tolerance of the grafted melon seedlings may have partially been the result of the decreased Na and Cl, and malondialdehyde contents and higher antioxidant enzyme activities.
A Construção do urbano-territorial na Amazônia : entendimentos práticos de Manaus e sua Região Metropolitana : o processo de contratação, elaboração e implementação dos PDUIs, contemplando as soluções de governança do plano, a definição dos instrumentos, os arranjos de gestão e a solução de conflitos de uso e ocupação do solo : componente B : relatório de pesquisa
Authors:   Instituto de Pesquisa Econômica Aplicada (Ipea)
Published: June 2021

Este texto se desdobra em duas principais discussões. A primeira sobre o arranjo jurídico e institucional acerca do histórico da criação da RM de Manaus e de seus instrumentos de gestão interfederativa – como seu primeiro Plano de Desenvolvimento Integrado (PDI) – e atividades de movimentos da sociedade civil, como o recente histórico de atuação do Observatório da Região Metropolitana de Manaus (ORMM), que vem contribuindo e qualificando a discussão metropolitana em Manaus, bem como orientando a discussão para a implantação do seu Plano de Desenvolvimento Urbano Integrado (PDUI) conforme legislação atual, qualificando sua gestão interfederativa e territorial. Em seu segundo momento, o texto se dedica à elucidação da natureza urbana na Amazônia e, especialmente, em Manaus e na região de forma a caracterizar sua singularidade no arranjo metropolitano nacional.
MODELLING RAIL THERMAL DIFFERENTIALS DUE TO BENDING AND DEFECTS
Authors: Bosomworth Chris , Spiryagin Maksym , Alahakoon Sanath , Cole Colin
Published: June 2021

Rail foot flaws have the potential to cause broken rails that can lead to derailment. This is not only an extremely costly issue for a rail operator in terms of damage to rolling stock, but has significant flow-on effects for network downtime and a safe working environment. In Australia, heavy haul operators run up to 42.5 t axle loads with trains in excess of 200 wagons and these long trains produce very large cyclic rail stresses. The early detection of foot flaws before a broken rail occurs is of high importance and there are currently no proven techniques for detecting rail foot flaws on trains at normal running speeds. This paper shall focus on the potential use of thermography as a detection technique and begin investigating the components of heat transfer in the rail to determine the viability of thermography for detecting rail foot flaws. The paper commences with an introduction to the sources of heat generation in the rail and modelling approaches for the effects of bending, natural environmental factors and transverse defects. It concludes with two theoretical case studies on heat generated due to these sources and discusses how they may inform the development of a practical thermography detection methodology.
Hit-and-stick Dust Collisions: Rotating Aggregate Targets
Authors: Lodge M. G.
Published: June 2021

Current models of dust aggregation in early planet formation describe numerous collision mechanisms in detail, but this research evaluates the impact of an idea that has not yet been explored: the effect of rotating targets on the probability of aggregate growth. Rotating target surfaces decrease the probability of successful sticking collisions due to an increased relative velocity between the colliding surfaces. A model has been developed to quantify this effect for use in dust evolution models. Curiously, the decrease in probability was found to almost exactly correlate to a quadratic function of the target angular velocity. For the range of target angular velocities between 0 and 100 rad s−1, the decrease in probability of sticking was calculated to be between 0% and 25% lower than predicted in a model that does not consider rotation, suggesting that dust may accumulate slower than previously thought in streaming stabilities.
Nutrient budgets in the Piratininga-Itaipu lagoon system (southeastern Brazil): effects of sea-exchange management
Authors: Cerda Mauricio , Nunes-Barboza Conceição Denise , Scali-Carvalho Camila Nunes , De Andrade-Jandre Kelly , Marques Jr Aguinaldo-Nepomuceno
Published: June 2021

The Piratininga-Itaipu Lagoon System and its drainage basin, located on the southeastern coast of Brazil, Niterói (RJ), has been the target of an intense process of urbanization over the last four decades. As a result of this process, both the lagoon and the adjacent sea area have shown signs of eutrophication due to the release of large quantities of domestic sewage semi (or not) treated. In an attempt to minimize these effects, in 2008 the government re-established a connection between the Piratininga lagoon and the sea. To evaluate changes and variations in the balance of dissolved inorganic nutrients, before and after interventions, the geochemical model of two stoichiometric mass balance boxes of the "LOICZ Program” (Land-Ocean Interactions in the Coastal Zone) was used. The salt and water balance showed different water residence times in the Piratininga lagoon for the two periods: 2005-2006 (before the opening of the connection between the Piratininga lagoon and the sea) and 2009-2010 (after the opening of the connection with the sea). The first period showed a value about two times higher than that obtained for 2009-2010, τ = 83 and 39 days respectively. The water residence time of the Itaipu lagoon did not show great variations between the two periods (τ = 9 and 8 days). For the period of 2005-2006, before the opening of the connection with the sea, both the lagoons were autotrophic (∆DIP > 0) and nitrogen loss was predominant (∆DIN < 0). The second period (2009-2010) was characterized by changes only in the trophic state of the Piratininga lagoon, which became heterotrophic (∆DIP > 0).
Gross chemical profile and calculation of nitrogen-to-protein conversion factors for nine species of fishes from coastal waters of Brazil
Authors: Diniz Graciela S. , Barbarino Elisabete , Oiano-Neto João , Pacheco Sidney , Lourenço Sergio O.
Published: June 2021

The amino acid composition and contents of nitrogen, phosphorus, lipid, carbohydrate and protein were determined in muscles of Dactylopterus volitans, Genypterus brasiliensis, Mullus argentinae, Paralichthys patagonicus, Percophis brasiliensis, Pinguipes brasilianus, Rhizoprionodon lalandii, Rhizoprionodon porosus, and Urophycis cirrata. The samples showed low carbohydrate content (<3.5% dry weight in all species) and were rich in protein (>66% dry weight in all species). The percentage of total lipid varied widely among species, and M. argentinae showed the highest concentrations (16%). The percentage of nitrogen and phosphorus was high and similar among species, with overall average values of 13.3% and 1.2%, respectively. The amino acids composition was similar among the animals, with glutamic acid and lisine as the most abundant amino acid and histidine in low concentrations. Among species, the content of proteinaceous nitrogen was high, with an average of 96.8% of the total nitrogen. From data of total amino acid and total nitrogen, specific nitrogen-to-protein conversion factors were calculated for each species. The nitrogen-toprotein conversion factors ranged from 5.39 to 5.98, with an overall average of 5.71. These findings showed that the traditional conversion factor of 6.25 overestimates the actual protein content and should be avoided.
Biological bases for whitebait culture Galaxias maculatus (Jenyns, 1842): a review
Authors: Vega Rolando , Dantagnan Patricio , Mardones Alfonso , Valdebenito Iván , Zamorano José , Encina Francisco
Published: June 2021

Galaxias maculatus (Jenyns, 1842), is a gourmet fish of great commercial importance with overexploited fisheries. So, studies of its biology are essential in order to develop a technology for its cultivation (galaxiculture), which is at a pilot stage. The goals of this work are: 1) to provide a synthesis of the literature information on the biology of the species, and 2) to identify the lack of scientific knowledge and critical points for the development of a technology for mass commercial culture. G. maculatus is a small carnivorous fish with euryhaline populations differentiated between diadromic and freshwater. Diadromic populations spawn in the estuaries, and then the larvae migrates to the sea, returning aged 6 months and metamorphosing into adults. Studies of their systematic, populations and larvae stage in Chilean waters are scarce, but studies on feeding, reproduction and diseases are more numerous. One year old females lay about 1,200 adhesive eggs and an important number of them die after the first spawning (40%). G. maculatus has rapid growth (1.1% day-1) and a high metabolism, with an average life of 2 years. They can be cultivated in captivity, spawn and incubate their eggs to obtain larvae; adults eat salmon starter pellets and grow in tanks. The ciliate protozoa Ichtyophthirius multifilis (ich) produces high mortality in larvae and adults in confinement; mortality can be controlled with salt bath. The problems to be solved by research for future commercial fish farming are: recognising and selecting suitable populations for cultivation; increasing the number of eggs spawned by females; develop suitable diets for larvae and broodstock; and controlling ectoparasitic diseases. The critical point is achieving mass production by improving the techniques of reproduction and larviculture.
The use of lactic acid bacteria isolated from intestinal tract of Nile tilapia (Oreochromis niloticus), as growth promoters in fish fed low protein diets
Authors: Lara-Flores Maurilio , Olvera-Novoa Miguel A.
Published: June 2021

In this study, the effect as growth promoter of five lactic acid strains (Enterococcus faecium, E. durans, Leuconostoc sp., Streptococcus sp. I and Streptococcus sp. II), isolated from intestinal tract of Nile tilapia (Oreochromis niloticus), was evaluated. Eight isocaloric diets were formulated: one containing 40% of protein as positive control, and seven with 27% protein. Five diets with 27% protein were supplemented with one of the isolated lactic acid bacteria in a concentration of 2.5x106 cfu g-1 of diet. A commercial probiotic based on S. faecium and Lactobacillus acidophilus was added at the same concentration to one 27% protein diet as a comparative diet, and the last diet was not supplemented with bacteria (negative control). Tilapia fry (280 mg basal weight) stocked in 15 L aquaria at a density of two per liter were fed for 12 weeks with experimental diets. Results showed that fry fed with native bacteria supplemented diets presented significantly higher growth and feeding performance than those fed with control diet. Treatment with Streptococcus sp. I isolated from the intestine of Tilapia produced the best growth and feeding efficiency, suggesting that this bacteria is an appropriate native growth promoter.
Analysis of the corvina gulf fishery as a function of management actions in the Upper Gulf of California, Mexico
Authors: Ruelas-Peña Joaquín Humberto , Valdez-Muñoz Carmen , Aragón-Noriega Eugenio Alberto
Published: June 2021

The gulf corvina (Cynoscion othonopterus), is an endemic species of the Gulf of California, and its fishery is one of the most important in the Upper Gulf of California. Two dynamic biomass models (Schaefer & Pella-Tomlinson), were used to assess the state of the stock due to the lack of enough age data for a reliable full age-structured stock assessment. The models required an historical annual time-series of the abundance index (from 1993 to 2010), derived from the commercial catch and effort data. The Akaike information criterion indicates that the best model was the Schaefer model. The maximum sustainable yield (MSY), estimated with the Schaefer model was 3.100 ton, with a maximum surplus biomass (BMSY) that will allow the capture of 8.200 ton, and a fishing effort (fMSY) of 457 boats. The fishing mortality (F = 0.43) was 26% higher than the fishing mortality at the biological reference point (F0.1 = 0.34). The average biomass from 2006 to 2010 was 52% of the optimum level of the fishery (Est2006-2010 < 1). In 1999 an increase of the fishing effort accelerated the decrease of the biomass. These results indicate that the stock has not been healthy, in spite of the Biosphere Reserve decree, because the core zone has not been respected as a prohibited zone for fishing, and because of the increased fishing effort.
Functional analysis of the food web of Bahia Magdalena, Baja California Sur, Mexico
Authors: Cruz-Escalona Víctor H. , Morales-Zárate María V. , Navia Andrés F. , Rguez-Baron Juan M. , Del Monte-Luna Pablo
Published: June 2021

In the present study we developed a trophic model (ECOPATH with ECOSIM), to describe the structure and functioning of Bahía Magdalena estuarine ecosystem. The model, constituted by 24 functional groups, indicates that one third of the total ecosystem biomass is produced by secondary and tertiary trophic levels. The magnitude of total flows in the system and the transfer efficiency among trophic levels, are similar to those observed in other tropical systems around the world. A large proportion of the total flows are directed to the maintenance of the trophic web structure. The value of the connectance index (CI) was 0.2, meaning that there is only 20% of realized connections within the web. Benthic primary producers contribute with 53% of the total ascendency. We believe that the energy control in this particular ecosystem is top-down type (through the main predators), suggesting that high-trophic level species negatively affect other groups in the system. This trophic model can be used for exploring different hypothesis concerning the biotic and abiotic mechanisms that modify the structure and functioning of the Bahía Magdalena ecosystem, with the ultimate goal of understanding how this attributes determine the resilience of marine communities.
Occurrence of South American fur seals Arctocephalus australis (Zimmermann, 1783) in San Matías Gulf, Patagonia, Argentina
Authors: Svendsen Guillermo Martín , Dans Silvana Laura , González Raúl Alberto , Romero María Alejandra , Crespo Enrique Alberto
Published: June 2021

The South American fur seal, Arctocephalus australis (SAFS) population suffered a drastic reduction due to commercial exploitation during the XVIII and XIX centuries. In the last decades a population recovery was detected in the Atlantic region. However, in this region, many aspects of the ecology of the SAFS, such as the post-reproductive dispersal of individuals, the location of feeding areas, and the movements of individuals between colonies on the boundaries of its distribution, are still unknown. Here, we report for the first time the occupation of San Matías Gulf (SMG, northern Patagonia, Argentina) by this species. We found that more than 1,600 SAFS used SMG between May and October (post-reproductive season) and detected a non-reproductive colony on Islote Lobos (41°24'S, 65°03'W). The presence of SAFS in SMG is recent and would be associated with an increase of the population on the Atlantic. The importance of SMG in the ecology of SAFS seems to lie on three factors: the strategic location in the geographic context of potential movements of individuals between distant colonies, the physical environment suitable for coastal settlements, and the availability of food resources.
Crustacean zooplankton species richness in Chilean lakes and ponds (23º-51ºS)
Authors: De los Ríos-Escalante Patricio
Published: June 2021

Chilean inland-water ecosystems are characterized by their low species-level biodiversity. This study analyses available data on surface area, maximum depth, conductivity, chlorophyll-a concentration, and zooplankton crustacean species number in lakes and ponds between 23º and 51ºS. The study uses multiple regression analysis to identify the potential factors affecting the species number. The partial correlation analysis indicated a direct significant correlation between chlorophyll-a concentration and species number, whereas the multiple regression analysis indicated a direct significant response of species number to latitude and chlorophyll-a concentration. These results agree with findings from comparable ecosystems in Argentina and New Zealand.
Progress and limitations of dsRNA strategies in the control of viral diseases in aquaculture
Authors: Papić Ljubomir , García Katherine , Romero Jaime
Published: June 2021

The development of a sustainable aquaculture is consistent with a growing demand for new methods to ensure the health of various aquatic species. Among them, the use of revolutionary therapies based on double-stranded RNA (dsRNA) has opened a wide range of possibilities in the progress of the control strategies and disease prevention. The system of gene silencing by RNA interference (RNAi) has an interesting potential for the control of infectious diseases in aquaculture systems. On the other side, it has been found that dsRNA can have a significant immunomodulatory effect in fish cells, activating innate immune defense mechanisms. The definition of a suitable delivery system to ensure the entry of dsRNA to the target cell has results in moderately successful assays. However, the delivery of dsRNA to ensure the entry to the organism in its natural habitat is the main difficulty of this technology. This work presents a comprehensive review of potential post-transcriptional silencing by dsRNA as antiviral strategy in fish farming and its potential use as an immunostimulant, emphasizing the need to seek methodologies to deliver dsRNA into the target organism, considering the limitations and characteristics of a system of intensive farming.
Dextrose as carbon source in the culture of Litopenaeus vannamei (Boone, 1931) in a zero exchange system
Authors: Suita Sabrina M. , Ballester Eduardo L.C. , Abreu Paulo C. , Wasielesky Jr. Wilson
Published: June 2021

This work compared the use of dextrose and molasses as carbon sources for biofloc development, water quality maintenance, microorganism composition and growth performance of Litopenaeus vannamei juveniles in biofloc technology (BFT). Two treatments, dextrose and molasses, were tested with four replicates each. Carbon was added to achieve a C:N-AT (N-(NH3+NH4+)) ratio of 6:1. Physical and chemical water quality variables were monitored daily, and shrimp growth was estimated through periodic biometry. After 30 days, survival, final biomass, and feeding conversion rate (FCR) were determined. Dissolved organic carbon, chlorophyll-a, floc volume, total ammonia, nitrite, nitrate and phosphate concentrations, and microorganisms (qualified by groups), were measured every three days. Water quality variables remained within acceptable levels throughout the experimental period, except for nitrite, which reached higher levels than recommended for this species. The use of dextrose resulted in higher water transparency, which influenced the remaining centric diatoms. A superior shrimp performance was observed at this treatment, presumably because of variations on the microbial community. Therefore, it is concluded that the addition of dextrose results in a superior growth performance of L. vannamei when cultured in BFT systems.
Digestible energy requirement for females of Rhamdia quelen on reproductive activity fed with ration based on vegetal ingredients
Authors: Bombardelli Robie A. , Sanches Eduardo A. , Tessaro Lucélia , Buzzi Alexandre H. , Martins Cleide V.B. , Meurer Fábio
Published: June 2021

The present experiment was carried out to evaluate the growth and reproductive parameters of Rhamdia quelen females fed with pelleted ration containing different levels of digestible energy, and to evaluate the vigor of their offspring. The breeders were placed in tanks under conditions of photoperiod and natural temperature. The fishes were fed for 255 days with isoproteic rations pelleted containing 35% of crude protein (CP) and five levels of the digestible energy (DE) (2700, 2950, 3200, 3450, 3700 kcal kg-1). The fishes were distributed in a randomized experimental design compounded by five treatments and three repetitions. A 16-m2 tank containing six females and three males was considered as one experimental unit. The weight and weight gain was evaluated. During the reproductive season the females were induced to breeding by hormonal manipulation and were evaluated the percentage of spawning females, the total fecundity, relative fecundity (number of oocytes per gram of spawning females), the fertilization ratio, the time to hatching and the vigor of larvae. The growth and reproductive parameters were not influenced (P > 0.05) by the increasing levels of digestible energy of the rations. The feeding of R. quelen females in breeding fit can be carried out with 2700 kcal kg-1 pelletized ration based on vegetal ingredients, without damage to reproductive performance.
Screening of aflatoxin B1 and mycobiota related to raw materials and finished feed destined for fish
Authors: Carvalho Gonçalves-Nunes Etelvina María , Gomes-Pereira Maria M. , Raposo-Costa Amilton P. , Da Rocha-Rosa Carlos A. , Pereyra Carina M. , Calvet Rodrigo M. , Alves-Marques Ana L. , Cardoso-Filho Francisco , Sanches-Murator Maria C.
Published: June 2021

The aim of the present study was to determine fungal genera, Aspergillus, Penicillium and Fusarium species and aflatoxin B1 contamination from raw materials and finished feed intended for fish farm localized in Piaui, Brazil. Aspergillus flavus and P. citrinum were isolated with a high relative density from all samples. In general, a high percent of samples exceeded the levels proposed as feed hygienic quality limits (CFU g-1) according to Good Manufacture Practice. Aflatoxin B1 was analyzed by enzyme-linked immunosorbent assay. All raw materials and finished feed showed aflatoxin B1 levels. Although in this study AFB1 levels below recommended limits (20 µg kg-1) were found, it is important to emphasize the feed intake with toxin in low concentrations along time, since it produce chronic deleterious effects in animal production. This fact requires periodic monitoring to prevent the occurrence of chronic aflatoxicosis in aquaculture, to reduce the economic losses and to minimize hazards to animal health.
Chemical composition of the freshwater prawn Cryphiops caementarius (Molina, 1782) (Decapoda: Palaemonidae) in two populations in northern Chile: reproductive and environmental considerations
Authors: Moreno-Reyes Jorge E. , Méndez-Ruiz Carlos A. , X. Díaz Gina , Meruane Jaime A. , Toledo Pedro H.
Published: June 2021

Reductions of its natural populations have led to recent efforts in small-scale aquaculture of the freshwater prawn Cryphiops caementarius, either for conservation or commercial purposes. However, the lack of knowledge about its nutritional requirements has been one of the major obstacles for its successful culture. Given its importance, this study determines and compares the chemical composition (moisture, ash, crude protein, total lipids and nitrogen free extract) of whole animals and main storage tissues (gonad, hepatopancreas and muscle), of C. caementarius adult prawns from two natural populations. Moreover, the relation of this composition with reproductive and environmental parameters (sex, maturation and habitat) is discussed. The specimens were collected in Limarí and Choapa rivers (Coquimbo, Chile) during reproductive season, and divided into six categories according to capture location, gonad maturation stage, and gender. The chemical composition of whole animals and storage tissues was compared among categories. Significant differences were observed between tissues, sexes, maturity stages and locations. Regarding tissues, the muscle and the gonads were rich in protein, whereas the hepatopancreas had high lipid content. According to results, factors such as sex, habitat and stage of gonad maturation can modify the biochemistry of C. caementarius. Nonetheless, the main chemical variations were observed in tissues involved in regulatory processes (hepatopancreas and gonads), and to a lesser extent in structural tissues (muscle). This is the first study known that reports information about the biochemistry of C. caementarius and its findings may be useful to improve feeding practices in aquaculture.
Molecular evidence of the protozoan parasite Marteilia refringens in Crassostrea gigas and Crassostrea corteziensis from the Gulf of California
Authors: Grijalva-Chon José Manuel , Castro-Longoria Reina , Enríquez-Espinoza Tania Lizbeth , Maeda-Martínez Alfonso Nivardo , Mendoza-Cano Fernando
Published: June 2021

The search for exotic pathogens related to the outbreaks and in surveillance samplings of the Mexican oyster farms, is a recent activity achieved by academic institutions and state committees for Aquatic Animal Health, with remarkable results. In samples of Crassostrea gigas collected through December 2009, January 2010 and November 2010, and of C. corteziensis in September 2011, the protozoan Marteilia refringens was detected for the first time in the Gulf of California. The carrier oysters were from cultures without abnormal mortality rates, whereby, the use of histology, in situ hybridization and transmission electron microscopy studies are necessary to determine if M. refringens has become established in the Gulf of California oyster cultures. Detection of M. refringens is of great concern to the global oyster farming industry.
Risk assessment and uncertainty of the shrimp trawl fishery in the Gulf of California considering environmental variability
Authors: Almendarez-Hernández Luis César , Ponce-Díaz Germán , Lluch-Belda Daniel , Del Monte-Luna Pablo , Saldívar-Lucio Romeo
Published: June 2021

The shrimp fishery off the Mexican Pacific coast is the country's most important fishery from the economic standpoint. However, it faces serious problems, including the fleet’s overcapitalization and age, in addition to the environmental variability that affects the size of catches. Thus, this activity depends on a variety of factors that add uncertainty to the profitability of fishing vessels. This study aims to estimate the probability of success and economic risk of "type vessels" under two different environmental variability scenarios in the Gulf of California. The results from the economic simulation pointed to the vessel type used in Guaymas (Sonora) as the most efficient one under a neutral climate change scenario, showing a homogeneous behaviour in physical characteristics and mode of operation. By contrast, under a scenario of a monotonic rise in sea surface temperature, the shrimp fishery faces a greater risk of incurring economic losses. The simulated climate behaviour scenarios revealed that the activity involves a moderate economic profitability under the neutral scenario; however, under the warming scenario, profitability may be low or even nil due to the risks and uncertainty resulting from the influence of environmental phenomena.
The use of ISSR markers for species determination and a genetic study of the invasive lionfish in Guanahacabibes, Cuba
Authors: Labastida Elizabeth , Cobián Dorka , Hénaut Yann , García-Rivas María del Carmen , Chevalier Pedro P. , Machkour-M'Rabet Salima
Published: June 2021

The red lionfish (Pterois volitans) and devil fire-fish (Pterois miles) are invasive species that pose a threat to the biodiversity and stability of coral reefs in the Western Atlantic, Gulf of Mexico and Caribbean Sea. Species identification of lionfish is uncertain in some parts of Cuba, and research has mainly been focused on their biology and ecology. The principal aim of this study was to determine highly polymorphic markers (Inter Simple Sequence Repeat, ISSR) that could be used in research on lionfish population genetics in addition to confirming the presence of Pterois species in the Guanahacabibes National Park. The genetic profile or “fingerprint” of individuals collected in Mexico, formally identified as P. volitans, was compared with the genetic profile of specimens from Cuba. There were very few “diagnostic bands” and a high number of "common bands", demonstrating that the same species exists in both countries. Furthermore, Nei's genetic distance and the unrooted tree do not show significant differences between both localities. In light of these results, we can confirm the presence of P. volitans in the Guanahacabibes National Park, Cuba. This study demonstrates the functionality of ISSR as a molecular tool for species identification and their application for genetic population studies of this invasive fish species.