Temperate Southern Research Articles

Projected impacts of future climate change on the aboveground biomass of seagrasses at global scale.

Seagrasses are crucial marine ecosystems that have experienced declines due to anthropogenic and climate change impacts. The projected future climate change suggests additional seagrass losses, but no global-scale estimates are currently available on the potential changes in aboveground biomass of seagrasses. We modelled and quantified the current potential aboveground biomass (AGB) of seagrasses on the global scale and projected future AGB under contrasting Shared Socioeconomic Pathway (SSP) scenarios, from low emissions (SSP1-1.9) to high emissions (SSP3-7.0 and SSP5-8.5). A machine learning algorithm (Boosted Regression Trees) fitted a comprehensive AGB dataset against biological and anthropogenic meaningful predictors. The model performed with high accuracy (deviance explained: 0.83), highlighting the role of genus and temperature conditions in defining global AGB patterns. The model estimated a present-day average AGB of 133.83 gDW·m2 (DW, dry weight) and a total global AGB of 0.0673 Pg DW. Future projections were highly dependent on the emission scenario, with losses in AGB ranging between 4.25% and 9.25% and in overall AGB between 9.96% and 10.26% across scenarios. Particularly, the higher emission scenario projected severe regional losses along the coastlines of the Tropical Eastern Pacific, the Eastern Indo-Pacific, the Temperate Northern Pacific, and the Tropical Atlantic, and gains along the Temperate Southern Africa and the Arctic regions. Our global estimates underline that fulfilling the Paris Agreement, as well as conserving and monitoring populations most affected by combined anthropogenic pressures would help to limit seagrass AGB declines, thereby supporting the multiple ecological services of seagrasses.

Antagonistic biotic interactions mitigate the positive effects of warming on wood decomposition.

Global change drivers such as habitat fragmentation, species invasion, and climate warming can act synergistically upon native systems; however, global change drivers can be neutralized if they induce antagonistic interactions in ecological communities. Deadwood comprises a considerable portion of forest carbon, and it functions as refuge, nesting habitat and nutrient source for plant, animal and microbial communities. We predicted that thermophilic termites would increase wood decomposition with experimental warming and in forest edge habitat. Alternately, given that predatory ants also are thermophilic, they might limit termite-mediated decomposition regardless of warming. In addition, we predicted that a non-native, putative termite-specialist ant species would decrease termite activity, and consequently decomposition, when replacing native ants. We tested these hypotheses using experimental warming plots (~ 2.5°C above ambient) where termites, and their ant predators, have full access and vary in abundance at microscales. We found that termite activity was the strongest control on decomposition of field wood assays, with mass loss increasing 20% with each doubling of termite activity. However, both native and non-native ant abundance increased with experimental warming and, in turn, appeared to equally limit termite activity and, consequently, reduced wood decomposition rates. As a result, experimental warming had little net effect on the decomposition rates-likely because, although termite activity increased somewhat in warmed plots, ant abundances increased more than five times as much. Our results suggest that, in temperate southern U.S. forests, the negative top-down effects of predatory ants on termites outweighed the potential positive influences of warming on termite-driven wood decomposition rates.

Where to forestation in dry-wet transition areas of China?

Where to forestation in dry-wet transition areas of China?

Barley vulnerability to climate change: perspectives for cultivation in South America.

Barley (Hordeum vulgare) is a globally significant cereal crop, widely used in both food production and brewing. However, it is particularly vulnerable to climate change, especially extreme temperature fluctuations, which can severely reduce yields. To address this challenge, a detailed climate zoning study was conducted to assess the suitability of barley production areas across South America, considering both current conditions and future climate scenarios from the Intergovernmental Panel on Climate Change (IPCC). The study utilized historical climate data along with projections from the CMIP6 IPSL-CM6A-LR model for the period 2021-2100. Several indices, such as evapotranspiration, were calculated, and factors like soil composition and topography were integrated into the classification of regions based on their agricultural potential. Critical variables in this assessment included temperature, precipitation, and water or thermal excess. The results showed that 6.59% of South America's territory is currently suitable for barley cultivation without additional irrigation, with these regions concentrated primarily in temperate southern areas. In contrast, 18.62% of the region is already unsuitable due to excessive heat. Projections under future climate scenarios indicate a shrinking of suitable areas, alongside an expansion of unsuitable regions. In the worst-case scenario, only 1.48% of the territory would remain viable for barley farming. These findings emphasize the crop's vulnerability to climate change, underscoring the urgency of developing agricultural adaptation strategies. The predicted contraction in suitable barley cultivation areas demonstrates the profound impact of climate change on agriculture and highlights the need for proactive measures to ensure sustainable barley production in South America.

Do Streptomyces sp. Help Mycorrhization in Raspberry?

Actinobacteria may help the mycorrhizal symbiosis by producing various bioactive metabolites. Mycorrhizae, in turn, are very important since they increase the absorption of nutrients, promoting the growth of their host plant and making inoculation with arbuscular mycorrhizae fungi (AM) a common practice applied in agriculture and forestry. The cultivation of Rubus idaeus (raspberry) is widespread in Patagonia, Argentina; however, the potential benefits of using actinobacteria-mycorrhizal inoculums to enhance crop growth and yield remain unexplored. The objective of this work was to study the interaction between actinobacteria (Streptomyces, Actinomycetota) and AM in raspberry plants. We performed an experiment applying 4 treatments to raspberry plants growing in two substrates, sterile soil and natural (non-sterile) soil. The treatments consisted in a control (without inoculation) and three inoculations treatments (AM, Streptomyces SH9 strain, and AM + Streptomyces). After 3months of inoculation, mycorrhization parameters (%) and plant growth were recorded. When comparing both substrates, the mycorrhization parameters were higher in natural soil than in sterile soil. The co-inoculation with AM + Streptomyces SH9 showed the highest mycorrhization. Both factors (treatment x substrate) interacted showing that in sterile soil the treatments with the highest effect on mycorrhization parameters were AM and the co-inoculation, while in natural soil all inoculations improved mycorrhization parameters, being highest with the co-inoculation. These results show that Streptomyces SH9 strain helps the mycorrhizal symbiosis in raspberry, being the first report about the effect of a native rhizospheric actinobacterium on an economically important species, promising potential for environmentally friendly improvements in raspberry crops within the temperate Southern Patagonian region.

Mixed stock analysis identifies natal origins of green turtles at foraging grounds in southeastern Australia

IntroductionIdentifying critical habitats for marine turtles and connectivity between genetic stocks and the foraging grounds they use is a conservation priority worldwide. Green turtles (Chelonia mydas) are impacted by a wide range of anthropogenic threats that can vary by geographic region and the ontogenetic stage of the individual. In Australia, the strengthening of the East Australian Current due to climate change is increasing ocean temperatures, particularly in southern New South Wales (NSW), which is having large-scale impacts on the distribution and abundance of marine resources. Green turtles are frequently observed in temperate southern NSW waters, but our knowledge of their habitat use, migration patterns and the impact of threatening processes is limited.MethodsTo assess the origins of green turtles from foraging grounds in southeastern Australia, samples were obtained from green turtles of all size classes (post-hatchlings to adults) that had stranded along an ~870 km expanse of the NSW coast and Lord Howe Island between 1997 and 2021. Mitochondrial DNA control region sequences for 283 individuals were compared to 25 potential source genetic stocks in the Indo-Pacific using mixed-stock analysis.ResultsA total of 26 haplotypes were identified in NSW, of which 14 had been previously observed at a rookery, eight had been identified previously, but not at a rookery (i.e. orphan haplotypes), and four were previously undescribed. Mixed-stock analysis revealed that NSW waters support multiple genetic stocks but are dominated by those of the southern Great Barrier Reef and New Caledonia genetic stocks. A small proportion of green turtles originated from more distant stocks in the Indo-Pacific region.DiscussionUnderstanding the connectivity between green turtle rookeries and foraging grounds provides an opportunity to assess the impact of anthropogenic threats to turtle stocks, and in turn, prioritize management actions for the conservation of green turtles across regional, national and international jurisdictions.

The Nutritional Year-Cycle of Italian Honey Bees (Apis mellifera ligustica) in a Southern Temperate Climate

Nutrition is a key aspect influencing honey bee health and overwintering. Since honey bee seasonality in southern temperate climates represents a significant research gap, this study conducted long-term monitoring of honey bees in the Mediterranean (Sassari, Italy). Specifically, individual weight, fat body, and size measurements (head, thorax, abdomen, and total body) were recorded monthly so to detect changes in the nutrient storage of worker bees during an annual cycle. Data were analysed according to sampling date, climate (temperature, precipitation, and daylength), and flower diversity and were conducted for nurse and forager bees separately. The nutritional honey bee year-cycle generally followed the nectar flow and showed two critical timepoints: summer and winter dearth. A short cessation of activities in late fall/early winter coupled with an increase in nutrient storage indicated the presence of winter bees. Precipitation was found to play an important role in honey bee nutrition in the study area through its impacts on colony demography and plants in particular illustrating how climate change could pose a threat to European honey bee populations in the future. These results provide valuable insights into the nutritional dynamics of Apis mellifera ligustica in the Mediterranean that could support management decisions to improve overwintering success and prevent unnecessary colony losses.

The Effect of Location, Time, and Environmental Conditions on Fish Use of Southern Temperate Saltmarshes

Fish use of saltmarsh varies spatially, temporally, and with environmental conditions. The specific impact of these effects on fish assemblages in southern temperate Tasmania, Australia—the only mangrove-free Australian state—is as yet largely unknown. Seasonal variation in fish abundance, richness, diversity, and size was investigated in succulent saltmarshes in three estuaries (Marion Bay, Barilla Bay, and Ralphs Bay) in south-eastern Tasmania. All parameters varied between sampling locations. Greater numbers of fish were recorded at two sites (Marion Bay, mean density and standard error of 396.9 ± 71.3 individuals per 100 m2; Barilla Bay, mean density and standard error of 94.1 ± 30.1 individuals per 100 m2) than have been previously reported in Australian saltmarshes. Fish abundance was greatest in July–August (mean density and standard error of 200.2 ± 49.7 individuals per 100 m2) reflecting the breeding patterns of the numerically dominant Atherinosoma microstoma. Both abundance and species richness responded positively to water temperature in ordinal logistic regression models, and species richness and diversity increased with water depth in the models. It is likely that the strong differences between sampling locations are partly related to differences in water depth and water temperature between the estuaries. They may be also related to the habitat context of each estuary, especially the presence or absence of seagrass. The greater numbers of fish found in the present study relative to abundances reported in mainland Australia may relate to the absence of mangroves and the consequent differences in seascape habitat context, including greater water depths in marshes. Importantly, these results demonstrate that temperate southern hemisphere saltmarshes are year-round habitat for fish, thus emphasising their importance as a fish habitat.

Per- and polyfluoroalkyl substances (PFAS) in little penguins and associations with urbanisation and health parameters

Per- and Polyfluoroalkyl substances (PFAS) are increasingly detected in wildlife and present concerning and unknown health risks. While there is a growing body of literature describing PFAS in seabird species, knowledge from temperate Southern Hemisphere regions is lacking. Little penguins (Eudyptula minor) can nest and forage within heavily urbanised coastal environments and hence may be at risk of exposure to pollutants. We analysed scat contaminated nesting soils (n=50) from 17 colonies in lutruwita/Tasmania for 16 PFAS, plasma samples (n=45) from nine colonies, and three eggs for 49 PFAS. We detected 14 PFAS across the sample types, with perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) most commonly detected. Mean concentration of PFOS in plasma was 2.56±4.3ng/mL (<LOD-22.3), soil was 2.92±5.39μg/kg (<LOD-29.8) and eggs were 11.89±11.30μg/kg (0.27-22.84). Mean concentration of PFHxS in plasma was 0.9±0.84ng/mL (<LOD-5.6), soil was 11.4±39.18μg/kg (<LOD-213.3) and eggs were 0.27±0.11μg/kg (<LOD-0.38). Urbanisation of breeding sites was positively associated with PFOS and PFHxS concentrations in soils and blood. Phenology appeared to be an important predictor of PFHxS load, with moulting birds having lower levels compared to non-moulting birds. We investigated PFAS associations with health parameters and found that haematocrit and total plasma proteins in females were negatively associated with PFOS and positively associated in males. The number of erythrocytic nuclear abnormalities in males was positively associated with PFOS. Findings are the first to document the presence of PFAS in this resident seabird nesting and foraging close to anthropogenically modified habitats. We demonstrate that even in low concentrations, PFAS may have detectable relationships with penguin health. Ongoing research is needed to investigate foraging ecology and trophic bioaccumulation pathways, as well as understand sublethal consequences from exposure.

Importance of (semi)natural vegetation on farms for achieving multiple objectives: A conceptual model based on temperate southern Australia

Importance of (semi)natural vegetation on farms for achieving multiple objectives: A conceptual model based on temperate southern Australia

Landscape scale control of selected mammalian predators fails to protect lizards

Invasive mammalian predators are a global biodiversity problem, particularly in archipelagos in which native fauna evolved in isolation from mammals. Landscape scale management of selected invasive mammalian predators is occurring across Aotearoa New Zealand to protect vulnerable forest birds and bats. In temperate southern beech forests, both predator irruptions and the timing of predator control is driven by mast seeding of beech trees. Relationships between predators targeted in this control, other invasive mammalian predators and other native taxa, particularly lizards and invertebrates, are poorly understood. We monitored southern grass skinks in the Eglinton Valley, Fiordland from 2009 to 2020 alongside monitoring of predators (stoats, rats and mice) in a system where predator control occurred in response to mast seeding. We evaluated relationships between skink abundance and abundance of rats (targeted in predator control operations) and mice (which also prey on small vertebrates like lizards, but are not controlled). Skink abundance declined over time and was negatively correlated with mouse abundance, but not correlated with rat abundance. Current landscape predator control to protect forest birds and bats is likely insufficient to protect ground-dwelling lizards, and may actually be detrimental to lizard populations if controlling the other predators contributes to a mesopredator release of mice. Mice are significant predators of a range of small vertebrates and large invertebrates, yet research into the sustainable suppression of mice to benefit vulnerable native populations is lacking. We strongly advocate for such research in order to deliver conservation management that benefits the full suite of biodiversity.

Genetic diversity of the polyphagous pest Rachiplusia nu across crops and locations in the Argentine Pampas

AbstractRachiplusia nu (Guenée) (Lepidoptera: Noctuidae, Plusiinae) is a defoliator of soybean (Glycine max L., Fabaceae), sunflower (Helianthus annuus L., Asteraceae), alfalfa (Medicago sativa L., Fabaceae), and horticultural crops in temperate southern South America; however, there is little genetic information available about this pest insect. Recently, concerns about this insect have increased because of its suspected resistance to Bt soybean and its spread to tropical regions. To better understand pest dynamics, and therefore implement suitable management strategies, a thorough knowledge of the genetic variability and spatial structuring of populations is required. In this paper, R. nu larvae were sampled from various crops and locations in central Argentina (where the pest is endemic) to assess diversity and population structure through mtDNA sequence analysis. In addition to the analysis of the standard cytochrome c oxidase subunit I (COI) ‘barcode’ fragment, a new set of primers was developed to explore genetic variation in the cytochrome b (Cytb) gene. COI and Cytb concatenated sequences revealed an overall high haplotype diversity (mean ± SD = 0.798 ± 0.037) and low nucleotide diversity (0.00137 ± 0.00013). The haplotype network showed a total of 19 haplotypes, separated by at most five mutational steps. A main central haplotype and four additional frequent haplotypes (accounting for 80% of the specimens examined) were distributed across populations with no obvious pattern related to host plant or geographic origin. Analysis of molecular variance further supported a weak population structure, where genetic variation within populations was the main source of total variation (ca. 96%). Pairwise comparisons showed only minor genetic differentiation among some of the populations studied. Implications of these findings in the context of R. nu control are discussed.

A Phytogeographical Classification and Survey of the Indigenous Browse Flora of South Africa, Lesotho, and Eswatini

Rangelands in South Africa, Lesotho, and Eswatini contain a rich diversity of valuable fodder trees and shrubs. This research is the first attempt to document the regional diversity and distribution of these browse resources. Scientific publications, textbooks, databases, and published reports were accessed to compile a database of plant species that were recorded as utilised by ruminants and non-ruminants. Relevant forage attributes, such as functional traits as well as utilisation traits, were added to each species record. Thereafter, distribution records were extracted from the South African National Biodiversity Institute’s Botanical Database of South Africa and analysed with numerical techniques to establish phytogeographical patterns. A total of 613 plant species from 76 families have been recorded, which formed seven distinct phytochoria, termed the Central Arid, Eastern Subtropical, Highland Temperate, Moist Temperate, Northern Subtropical, Southern Temperate, and Western Arid browse-choria. Key families and species, as well as functional and utilisation traits, are discussed, focusing on key species present in the browse-choria. This browse database, together with the earlier compiled Leguminosae and Poaceae databases, will be used to prioritise indigenous southern African plant species/infraspecific taxa to be collected for the conservation of genetic resources and future evaluations for potential development as forage crops.

Freshwater ascomycetes from southern Australia: Melanascomaceae fam. nov., Melanascoma panesporagen. et. sp. nov., and Pleurotheciumbruniussp. nov.

During a survey of freshwater fungi in temperate southern Australia, two new taxa were found, Melanascoma panespora and Pleurothecium brunius. Morphological and molecular data place Melanascoma panespora in the Diaporthomycetidae representing a new genus. Melanascoma, along with Proliferophorum and Paraproliferophorum, form a new lineage and the family Melanascomaceae is introduced. Phylogenetic analyses using ITS, 28S, and 18S nrRNA gene sequences,, along with morphological examination revealed Pleurothecium brunius to be a new species of Pleurothecium, sister to P. aquaticum. Citation: Fryar SC, Catcheside DEA (2023). Freshwater ascomycetes from southern Australia: Melanascomaceae fam. nov., Melanascoma panespora gen. et. sp. nov., and Pleurothecium brunius sp. nov. Fungal Systematics and Evolution 11: 85-93. doi: 10.3114/fuse.2023.11.07.

A Tale of Two Continents (and a Few Islands): Ecology and Distribution of Late Pleistocene Sloths

Late Pleistocene sloths were widely distributed and present in a diversity of habitats in South, Central, and North America and some Caribbean Islands. Late Pleistocene sloths include 27 genera in four families Megatheriidae, Megalonychidae, Mylodontidae, and Nothrotheriidae. There is no consensus on the number of valid species. Some sloths have wide geographic distributions and are present on multiple continents while others have a much smaller distribution. Our knowledge of the paleoecology and natural history of the different sloths varies greatly depending on their relative abundance. The wide distribution of sloths and adaptations to different habitats results in several “sloth” faunas with different taxonomic compositions. These generalized faunas can be distinguished geographically as Temperate North America (five genera), Southern Mexico and Central America (five genera), Northern South America (two genera), West Coast of South America (four genera), the Andes and Altiplano (four genera), Brazilian Intertropical Region (nine genera), Pampas-Patagonia and the Caribbean Islands (Cuba, Hispaniola, and Puerto Rico, four genera). Some genera may occur in multiple regions but are represented by different species. These regions also have differences in other mammalian taxa, so the sloths are often in ecological competition with different megaherbivores or preyed on by different carnivores.

Recent Population Dynamics of Japanese Encephalitis Virus.

Japanese encephalitis virus (JEV) causes acute viral encephalitis in humans and reproductive disorders in pigs. JEV emerged during the 1870s in Japan, and since that time, JEV has been transmitted exclusively throughout Asia, according to known reporting and sequencing records. A recent JEV outbreak occurred in Australia, affecting commercial piggeries across different temperate southern Australian states, and causing confirmed infections in humans. A total of 47 human cases and 7 deaths were reported. The recent evolving situation of JEV needs to be reported due to its continuous circulation in endemic regions and spread to non-endemics areas. Here, we reconstructed the phylogeny and population dynamics of JEV using recent JEV isolates for the future perception of disease spread. Phylogenetic analysis shows the most recent common ancestor occurred about 2993 years ago (YA) (95% Highest posterior density (HPD), 2433 to 3569). Our results of the Bayesian skyline plot (BSP) demonstrates that JEV demography lacks fluctuations for the last two decades, but it shows that JEV genetic diversity has increased during the last ten years. This indicates the potential JEV replication in the reservoir host, which is helping it to maintain its genetic diversity and to continue its dispersal into non-endemic areas. The continuous spread in Asia and recent detection from Australia further support these findings. Therefore, an enhanced surveillance system is needed along with precautionary measures such as regular vaccination and mosquito control to avoid future JEV outbreaks.

Paleocene fossil wood from Patagonia with storied rays and comments on the fossil record of this character

Summary The storied structure in wood anatomy is considered derived and highly specialized, and is present in some related families. The first records of this character are from the Cretaceous, but it is scarce in the Cretaceous and Paleocene, and apparently absent until the Eocene in the temperate Southern Hemisphere. Using standard methodology, we describe the anatomy of a fossil wood from the early Paleocene of Patagonia (Salamanca Formation). The fossil wood, assigned to a new genus and species Elizabethiaxylon patagonicum related to the Malvaceae, is characterized by its diffuse-porous wood, solitary vessels, simple perforation plates, apotracheal banded axial parenchyma, and mostly biseriate storied rays. The storied structure in this wood is one of the oldest records from Gondwana.

Concise review of genus Lessonia Bory

Abstract Lessonia (order Laminariales) is a kelp genus restricted to the temperate southern hemisphere, where species form dense forests from the low intertidal to 25 m depth at wave exposed sites. Lessonia spp. are among the most harvested kelps globally due to their importance in providing raw materials for food, cosmetics, bioactive and biomedical industries. Over-harvesting of natural beds can negatively affect Lessonia populations and the many species that depend on these habitats, including commercially important fish and molluscs, but good harvest management plans reduce these impacts on natural Lessonia stocks. However, the increasing demand for raw materials will likely only be met by aquaculture for which Lessonia shows high potential in pilot scale studies undertaken in Chile, New Zealand, and Australia. In this concise review, we highlight the current knowledge of Lessonia spp. taxonomy and distribution, life history, ecology and ecosystem services, wild harvest, aquaculture, and commercial applications. We discuss future research directions.

Microplastics in a pelagic squid (Dosidicus gigas) from the Eastern tropical Pacific Ocean: Characteristics, spatial variation, and preliminary risk assessment

Despite concerns about the environmental impact of microplastics (MPs), knowledge of MP contamination levels in pelagic squid is lacking. This study investigated the stomach of an ecologically and commercially important but poorly known squid species, the jumbo squid Dosidicus gigas, found in the tropical and Southern temperate Pacific. We examined the characteristics and spatial distribution of MPs in fifty D. gigas (16.0–37.8 cm mantle length) and assessed potential MP pollution risks. MPs were detected in 50.0% of specimens and had an average abundance of 0.88 ± 1.12 items/individual and 0.24 ± 0.36 items/g stomach weight, and were sized 58.42–2,944.85 μm. The MPs were dominated by polyethylene terephthalate (31.82%) in polymer type, fragments (54.55%) and fibers (43.18%) in shape, and blue (59.59%) in color. All specimens could be evaluated as low risk. No statistically significant correlations were found between the MP abundances and D. gigas stomach weight, stomach fullness index, distance from the coast, and mantle length. While regression analyses showed that fuller stomachs contained larger MPs. Spatial variations in shape and polymer composition suggest that low-density fibrous MPs could be easily transported offshore by upwelling and/or ocean currents. These results indicate intraspecific variation in D. gigas MP contaminants and underscore the need to assess the potential site-specific ecotoxicological consequences of increased plastic pollution to pelagic squid.

Established but not spreading: the tropical invasive snail Melanoides tuberculata in a geothermally warmed channel in temperate Southern Pampas

Melanoides tuberculata is a freshwater snail native to Old World tropical areas but has invaded tropical and subtropical regions around the world. In Argentina, populations established in natural environments were reported from northeastern tropical provinces. Here we report for the first time the presence of M. tuberculata in a geothermally warmed channel in temperate Southern Pampas. We mapped its distribution in the channel, searched for its presence in five nearby basins, estimated the risk of establishment and expansion in Argentina with distribution models and analyzed shape variation through geometric morphometrics. Melanoides tuberculata was recorded exclusively in the channel in sites with temperatures between 20 and 40°C, with almost no overlap with other snails. No evidence of M. tuberculata was found in nearby basins. The distribution model predicted that only northernmost areas from Argentina are suitable for this species, where it could impact snail communities and food webs if introduction through the aquarium trade is not prevented. The absence of males indicates parthenogenetic reproduction and probably a recent invasion. Shell shape variation in this population, 15 % of which is attributable to allometry, encompasses the shapes of specimens from other South American populations, suggesting that all belong to the same lineage.