Latitudinal Gradient Research Articles

Densities of Eurasian Three-toed Woodpecker Picoides tridactylus and sap trees correlate across a latitudinal gradient in Sweden

Densities of Eurasian Three-toed Woodpecker Picoides tridactylus and sap trees correlate across a latitudinal gradient in Sweden

Climatology and variability of sea surface temperature in the Azores region and its relation to climate indices

Daily sea surface temperature (SST) data from the Advanced Very High Resolution Radiometer from 1982 to 2020 were used to study the spatiotemporal variability and climatology of SST in the Azores. In addition, the relationships between the SST anomaly (SSTA) and three climate index time series for the period 1982–2020 were investigated: the Oceanic Niño Index (ONI), the Southern Oscillation Index (SOI) and the North Atlantic Oscillation (NAO) index. The spatiotemporal variability and climatology of the SST were studied by analyzing annual, seasonal, and monthly mean SST time series and climate fields. Relationships between the SSTA and climate index time series were investigated using Pearson's correlation analysis and wavelet coherence analysis. The annual mean SST time series shows a positive linear trend of about 0.027°C per year over the period 1982–2020. The spatial variability of the linear trend shows that the positive trend is consistent throughout the study area, ranging from 0.024 to 0.034°C per year. The spatial variability is not uniform, and high values of the trend are observed in the upper northwestern part and southwestern half of the basin. Seasonal mean SST fields show a positive North-South latitudinal gradient, with higher temperatures in the south, especially in the southwestern basin. In addition, the seasonal mean SST fields show possible coastal upwelling signatures along the coast of the Azores islands in different seasons. The results of Pearson's correlation analysis between basin-averaged, de-trended monthly mean SSTA and climate indices show that SSTA shows a significant positive correlation with SOI and a negative correlation with ONI from 1982 to 2020. NAO shows positive correlation with SSTA for the December-January-February season. Wavelet coherence analysis confirms significant coherences between the Azores SSTA and the climate-ocean indices at certain time scales and periods.

Climate determines diversity but not abundance of nitrogen-cycling microorganisms in rivers across a latitudinal gradient

A central goal in microecology is to understand the ecological factors shaping spatial patterns of microbial communities and the underlying mechanisms. However, the biogeographical patterns of microbial functional groups involved in nitrogen cycling (e.g., nitrifiers and denitrifiers) and their drivers at a large scale remain poorly understood. In this study, we evaluated the geographical distributions of nitrifiers and denitrifiers in riparian rhizosphere soils, riparian bulk soils, and channel sediments of 30 river regions along a latitudinal gradient from 21.8°N to 45.1°N across eastern China. We found that the diversity of nitrifiers and denitrifiers exhibited a gradual latitudinal gradient, in direct contrast to no significant changes observed for their abundance along the same latitudinal gradient. Statistical analyses suggested that climatic factors (mean annual temperature and mean annual precipitation) were the major drivers for the diversity of nitrifiers and denitrifiers, whereas soil properties were the key environmental factors shaping the abundance of nitrifiers and denitrifiers. Overall, these results provide new insights into the biogeographical distributions and ecological drivers for nitrogen-cycling microorganisms in river ecosystems at a large scale and can help us to improve the simulation models of the nitrogen cycle for accurately predicting the diversity of nitrogen-cycling microbes under ongoing climate changes.

Ecology and behaviour of the invasive lionfish Pterois miles colonizing coastal areas of the central Mediterranean

Biodiversity redistribution is occurring at an unprecedented pace, with one prominent example being the invasion of the lionfish (Pterois miles) in the Mediterranean Sea, altering the fish community composition by creating novel interspecific interactions and potentially threatening local biodiversity. Our study attempts to identify patterns in the lionfish distribution and behaviour in the coastal zone of the eastern Ionian Sea (central Mediterranean). Over a 14-month period, visual censuses were conducted along coastal strip transects at six stations, situated in three areas (Mani, Katakolo, Astakos) across a latitudinal gradient. Lionfish density was highest in Mani, the southernmost area. Higher densities were found at two stations experiencing direct anthropogenic pressures: one with structural modifications by port infrastructure, and the other in the vicinity of a fish farm, indicating a potential role of human interventions in facilitating the establishment of invasive populations. Lionfish group size was influenced by overall density, exhibiting variation between the two natural stations. Lionfish activity levels by microhabitat were site-specific, with more inactive individuals in crevices. Temporal activity patterns were similar in the natural stations, with increased activity during spring and summer months; however, temporal activity patterns were not identical in the two anthropogenic sites, suggesting that the specific nature of anthropogenic intervention might possibly influence lionfish activity. Finally, lionfish densities were not significantly different between early morning and late afternoon times of day, in agreement with the crepuscular behaviour already documented for this species.

Response of beech and fir to different light intensities along the Carpathian and Dinaric Mountains

Predicting global change mitigations based on environmental variables, like temperature and water availability, although yielding insightful hypothesis still lacks the integration of environmental responses. Physiological limits should be assessed to obtain a complete representation of a species’ fundamental niche. Detailed ecophysiological studies on the response of trees along the latitudinal gradient are rare. They could shed light on the behaviour under different light intensities and other studied traits. The forests of the Dinaric Mountains and the Carpathians represent the largest contiguous forest complexes in south-eastern Europe. In uneven-aged Carpathian (8 plots) and Dinaric Mountain (11 plots) forests, net assimilation (Amax) and maximum quantum yield (Φ) were measured for beech and fir in three predefined light intensity categories according to the indirect site factor (ISF%) obtained by the analysis of hemispherical photographs in managed and old growth forests, all located above 800 m a.s.l. The measurements were carried out under fixed environmental conditions in each light category per plot for three consecutive years. Data from the last 50-year average period from the CRU TS 4.01 dataset were used for the comparison between Amax, Φ, and climate. The highest Φ for beech were observed in the central part of the Dinaric Mountains and in the south westernmost and northwesternmost part of the Carpathians for both beech and fir, while they were highest for fir in the Dinaric Mountains in the northwesternmost part of the study area. The Φ-value of beech decreased in both complexes with increasing mean annual temperature and was highest in the open landscape. For fir in the Carpathians, Φ decreased with increasing mean annual temperature, while in the Dinaric Mountains it increased with higher temperature and showed a more scattered response compared to the Carpathians. Short-term ecophysiological responses of beech and fir were consistent to long-term radial growth observations observed on same locations. The results may provide a basis and an indication of the future response of two tree species in their biogeographical range to climate change in terms of competitiveness, existence and consequently forest management decisions.

Temperature sensitivity of aerobic and anaerobic organic carbon mineralization varies with climate and soil depth in riparian zones

The temperature sensitivity (Q10) of soil organic carbon (SOC) mineralization plays a vital role in predicting the global carbon cycle under climate change. Q10 has been extensively examined in various terrestrial ecosystems; however, in riparian zones where soil oxygen levels are highly dynamic owing to frequent flooding, Q10 should change with oxygen conditions and show spatial variation, but the mechanisms are still obscure. In this study, we collected topsoil and subsoil samples from riparian zones along a latitudinal gradient and conducted aerobic and anaerobic incubation experiments to determine the latitudinal and vertical patterns of Q10. The results showed that Q10 under anoxic conditions (average of 1.7) significantly exceeded that under oxic conditions (average of 1.4). In general, aerobic SOC mineralization is more sensitive to warming at higher latitudes than at lower latitudes, whereas the pattern is reversed under anoxic conditions. The Q10 in the topsoil was significantly higher than that in the subsoil only under oxic conditions. Metagenomics showed that the abundance of genes involved in the degradation of lignin, carbohydrate esters, and starch in the topsoil increased with latitude, whereas genes for acetate degradation were more abundant in warmer zones, regardless of soil depth. Q10 under oxic conditions was mainly influenced by soil physicochemical properties (e.g., pH and texture), whereas Q10 under anoxic conditions was jointly controlled by climate, soil texture, and acetate degradation genes. Together, anaerobic carbon (C) mineralization in riparian zones is more sensitive to temperature than aerobic metabolism, but the patterns of Q10 under oxic conditions were dependent on both latitude and depth. Our findings highlight that the discrepancies in aerobic and anaerobic C metabolism, and the C cycling process at different soil depths, might play a non-negligible role in affecting the assessment of global C emissions under climate change.

Non-indigenous species and their realized niche in tidepools along the South-East Pacific coast

Non-indigenous species (NIS) have the potential to colonize and become established in a wide range of coastal habitats. Species with broad environmental tolerances can quickly adapt to local conditions and expand their niches along environmental gradients, and even colonize habitats with extreme abiotic conditions. Here we report and document the distribution of eight marine NIS (four seaweed and four invertebrate species) found in tidepools along a 3,000 km latitudinal gradient along the Pacific coast of Chile (18.4°S to 41.9°S). The seaweed NIS Codium fragile, Capreolia implexa, Schottera nicaeensis and Mastocarpus latissimus were mostly distributed towards high latitudes (i.e., more southerly locations), where temperatures in tidepools were low. The invertebrate NIS Anemonia alicemartinae, Ciona robusta, Bugula neritina and Bugulina flabellata were more common towards low latitudes, where high temperatures were registered in the tidepools. Across the intertidal gradient, seaweed NIS were mostly found in pools in the mid and low intertidal zone, while invertebrate NIS occurred mostly in pools from the mid and upper intertidal zones. The realized niche spaces of NIS (based on the Outlying Mean Index, OMI) in the study area were mainly influenced by environmental conditions of temperature and salinity (along the latitudinal and intertidal gradients), while other tidepool characteristics (depth, surface area, exposition, and complexity) only had minor effects. Five of the eight NIS exhibited a realized niche space coinciding with the average tidepool environmental conditions, while marginal niches were occupied by species with affinities for specific temperatures and salinities along the latitudinal and intertidal gradients. Our results indicate that physiological tolerances to environmental factors play a fundamental role in the distribution of seaweed and invertebrate NIS in tidepools along the Chilean coast. This study confirms that tidepools offer suitable conditions for some seaweed and invertebrate NIS, potentially facilitating their invasion into new natural habitats.

Variety is the spice: the role of morphological variation of Triatoma infestans (Hemiptera, Reduviidae) at a macro-scale§

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi (Chagas, 1909). One of the primary vectors of T. cruzi in South America is Triatoma infestans (Klug, 1834). This triatomine species is distributed across a huge latitudinal gradient, inhabiting domiciliary , peridomiciliary , and wild environments. Its wide geographic distribution provides an excellent opportunity to study the relationships between environmental gradients and intraspecific morphological variation. In this study, we investigated variations in wing size and shape in T. infestans across six ecoregions. We aimed to address the following questions: How do wing size and shape vary on a regional scale, does morphological variation follow specific patterns along an environmental or latitudinal gradient, and what environmental factors might contribute to wing variation? Geometric morphometric methods were applied to the wings of 162 females belonging to 21 T. infestans populations, 13 from Argentina (n = 105), 5 from Bolivia (n = 42), and 3 from Paraguay (n = 15). A comparison of wing centroid size across the 21 populations showed significant differences. Canonical Variate Analysis (CVA) revealed significant differences in wing shape between the populations from Argentina, Bolivia, and Paraguay, although there was a considerable overlap, especially among the Argentinian populations. Well-structured populations were observed for the Bolivian and Paraguayan groups. Two analyses were performed to assess the association between wing size and shape, geographic and climatic variables: multiple linear regression analysis (MRA) for size and Partial Least Squares (PLS) regression for shape. The MRA showed a significant general model fit. Six temperature-related variables, one precipitation-related variable, and the latitude showed significant associations with wing size. The PLS analysis revealed a significant correlation between wing shape with latitude, longitude, temperature-related, and rainfall-related variables. Wing size and shape in T. infestans populations varied across geographic distribution. Our findings demonstrate that geographic and climatic variables significantly influence T. infestans wing morphology.

Plant dispersal in the Devonian world (c. 419–359 Ma)

AbstractDispersal, whether active or passive, plays a crucial role in biogeography by facilitating the movement of propagules away from their original location. Botanical geographical zonation, resulting from the co‐evolution of plants and their environment, has been established since the remarkable plant diversification during the Devonian Period (c. 419–359 Ma). However, a significant knowledge gap exists in understanding plant dispersal between living and fossil organisms due to the rarity of opportunities for tracing plant dispersal in geological history. In this study, we present evidence of two plant dispersal routes and verify their occurrence through the examination of geographical zonation, changes in plant diversity, and latitudinal and longitudinal gradients during the Devonian. We analyse global occurrence data from widely‐distributed and extensively‐studied Devonian plants. The two dispersal routes, namely clockwise and anticlockwise, connect the South China and Euramerica–Siberia realms. These routes clearly demonstrate inland and inter‐land dispersal models, closely linked to Devonian sea–land topography and dispersal vectors such as wind and ocean currents. Moreover, these models probably apply to all Devonian plants. Our comprehensive synthesis of plant dispersal in deep time reveals that propagule diversity and dispersal vectors have progressively increased and become more complex over time, facilitating plant colonization and diversity changes. Importantly, our study unveils the dispersal models of fossil plants, demonstrating the equivalent models observed in extant plants that have been established since the Devonian Period.

Разнообразие и закономерности распространения Bazzania (Lepidoziaceae, Marchantiophyta) в притихоокеанской Азии с особым вниманием к роду во Вьетнаме

The distribution of Bazzania in Pacific Asia excluding Malesia is surveyed. The taxonomic diversity in this genus increases from North to South, while the regional taxonomic composition of Bazzania is rather gradually changes and compared regions are distributed strictly along a latitudinal gradient on the DCA scatter plot. Particular attention is paid to the distribution of Bazzania in Vietnam, for which considerable data were obtained in recent decade. A list of Bazzania of Pacific Asia is provided with distribution by country, as well as more detailed species list for this genus in Vietnam. The world centers of Bazzania species diversity are located in Malesia and Melanesia, where the former is adjacent to Pacific Asia in the northwest. Bazzania siamensis comb. nov. is proposed, the species is treated as different from B. pearsonii with which it was synonymized before. A description and photographs of the species based on lectotype are provided.

New Insights into Tetraplosphaeriaceae Based on Taxonomic Investigations of Bambusicolous Fungi and Freshwater Fungi

Species within Tetraplosphaeriaceae have been frequently documented in recent years with the extensive investigations of microfungi along a latitudinal gradient from north to south in the Asian/Australian region. Both bamboo substrates and freshwater habitats serve as extensive reservoirs, hosting a rich diversity of fungi that exhibit broad geographical distributions. The most common fungi in these two environments are generally distributed in distinct families. However, our statistics have revealed an intriguingly distinct preference of Tetraplosphaeriaceae species for inhabiting both bamboo substrates and freshwater habitats. The genera Pseudotetraploa (100%) and Triplosphaeria (100%) exhibit a strong preference, followed by Shrungabeeja (71%) and Quadricrura (67%). Our taxonomic and phylogenetic study of microfungi in southern China have identified four additional novel species, viz., Aquatisphaeria bambusae sp. nov., Pseudotetraploa phyllostachydis sp. nov., Pseudotetraploa yangjiangensis sp. nov., and Tetraploa submersa sp. nov. from bamboo substrates and freshwater habitats. In addition, Aquatisphaeria thailandica has previously been documented from freshwater habitats in Thailand; however, we have once again isolated this species from decaying bamboo substrates in Guangdong, China. The new findings substantiate our hypothesis that the preference of Tetraplosphaeriaceae species for colonizing bamboo substrates and freshwater habitats will be more evident through more extensive investigations conducted in such environments.

Urbanization alters the geographic patterns of passerine plumage color in China

Urbanization has altered natural landscapes and serves as an environmental filter that selects species with specific traits. Coloration is an important trait associated with biotic interactions and thermoregulation, enabling species’ survival and reproductive success. However, few studies have focused on how species coloration changes in response to urbanization. Here, we used 547 passerine bird species from 42 cities and their corresponding non-urban communities in China to test whether urban species are darker and if they have duller plumage colors than their non-urban counterparts. Furthermore, we examined whether and how urbanization influences avian plumage color homogenization and the extent to which urbanization has altered the strength of the color–latitude geographic pattern in passerine birds across China. We found a 3.2% loss in the coloration space of birds after urbanization, although there were no significant differences in the individual dimensions of colorfulness and lightness between urban and non-urban birds. Avian communities in cities exhibited more plumage color homogenization than those in non-urban communities. There were significant latitudinal gradients in plumage colorfulness and lightness in non-urban communities, but these correlations were weaker in urban communities. Non-urban communities that were more colorful and lighter tended to be duller and darker in urban environments, and vice versa. Our results provide national-scale evidence that urbanization has led to reduced color diversity, increased color-based community similarity, and altered geographic patterns of avian plumage color gradients in China. These findings provide new insights into how rapid human-induced environmental changes have affected animal coloration during the Anthropocene.

Arctic cyanobacterial mat community diversity decreases with latitude across the Canadian Arctic.

Cyanobacterial mats are commonly reported as hotspots of microbial diversity across polar environments. These thick, multi-layered microbial communities provide a refuge from extreme environmental conditions, with many species able to grow and coexist despite the low allochthonous nutrient inputs. The visibly dominant phototrophic biomass is dependent on internal nutrient recycling by heterotrophic organisms within the mats, however the specific contribution of heterotrophic protists remains little explored. In this study, mat community diversity was examined along a latitudinal gradient (55-83°N), spanning subarctic taiga, tundra, polar desert, and the High Arctic ice shelves. The prokaryotic and eukaryotic communities were targeted respectively by V4 16S and V9 18S rRNA gene amplicon high-throughput sequencing. Prokaryotic and eukaryotic richness decreased, in tandem with decreasing temperatures and shorter seasons of light availability, from the subarctic to the High Arctic. Taxonomy-based annotation of the protist community revealed diverse phototrophic, mixotrophic and heterotrophic genera in all mat communities, with fewer parasitic taxa in High Arctic communities. Co-occurrence network analysis identified greater heterogeneity in eukaryotic than prokaryotic community structure among cyanobacterial mats across the Canadian Arctic. Our findings highlight the sensitivity of microbial eukaryotes to environmental gradients across northern high latitudes.

The effects of human population density on trophic interactions are contingent upon latitude

AbstractAimGlobal‐scale studies are necessary to draw general conclusions on how trophic interactions vary with urbanization and to explore how the effects of urbanization change along latitudinal gradients. We predict that the intensity of trophic interactions decreases in response to urbanization (quantified by human population density). Since trophic interactions are more intense at lower latitudes, we also expect major impacts of urbanization at higher latitudes, where base levels are essentially lower.LocationGlobal (881 study sites).Time period2000–2021.Major taxa studiedBirds, arthropods and woody plants.MethodsWe compiled global data on insect herbivory and bird predation from studies that employed similar methods and fitted generalized linear mixed models to test how these trophic interactions vary with human population density, latitude and their interactions.ResultsThe intensity of herbivory and predation decreased with an increase in human population density at lower latitudes. Surprisingly, it remained unaffected at intermediate latitudes and even increased at higher latitudes.Main conclusionsThe observed patterns may be attributed to local climate changes in urban areas, such as the Urban Heat Island effect, which disrupts thermal stability in the tropics while increasing niche availability at polar latitudes.

Testing the deep‐sea glacial disturbance hypothesis as a cause of low, present‐day Norwegian Sea diversity and resulting steep latitudinal diversity gradient, using fossil records

AbstractAimWithin the intensively‐studied, well‐documented latitudinal diversity gradient, the deep‐sea biodiversity of the present‐day Norwegian Sea stands out with its notably low diversity, constituting a steep latitudinal diversity gradient in the North Atlantic. The reason behind this has long been a topic of debate and speculation. Most prominently, it is explained by the deep‐sea glacial disturbance hypothesis, which states that harsh environmental glacial conditions negatively impacted Norwegian Sea diversities, which have not yet fully recovered. Our aim is to empirically test this hypothesis. Specific research questions are: (1) Has deep‐sea biodiversity been lower during glacials than during interglacials? (2) Was there any faunal shift at the Mid‐Brunhes Event (MBE) when the mode of glacial–interglacial climatic change was altered?LocationNorwegian Sea, deep sea (1819–2800 m), coring sites MD992277, PS1243, and M23352.Time period620.7–1.4 ka (Middle Pleistocene–Late Holocene).Taxa studiedOstracoda (Crustacea).MethodsWe empirically test the deep‐sea glacial disturbance hypothesis by investigating whether diversity in glacial periods is consistently lower than diversity in interglacial periods. Additionally, we apply comparative analyses to determine a potential faunal shift at the MBE, a Pleistocene event describing a fundamental shift in global climate.ResultsThe deep Norwegian Sea diversity was not lower during glacial periods compared to interglacial periods. Holocene diversity was exceedingly lower than that of the last glacial period. Faunal composition changed substantially between pre‐ and post‐MBE.Main conclusionsThese results reject the glacial disturbance hypothesis, since the low glacial diversity is the important precondition here. The present‐day‐style deep Norwegian Sea ecosystem was established by the MBE, more specifically by MBE‐induced changes in global climate, which has led to more dynamic post‐MBE conditions. In a broader context, this implies that the MBE has played an important role in the establishment of the modern polar deep‐sea ecosystem and biodiversity in general.

Continental-scale migration patterns and origin of Helicoverpa zea (Lepidoptera: Noctuidae) based on a biogeochemical marker.

Insect migrations have ecological and economic impacts, particularly in agriculture. However, there is limited knowledge about the migratory movements of pests at the continental scale, which is an important factor influencing the spread of resistance genes. Understanding the migratory patterns of economic pests, like Helicoverpa zea (Boddie), is essential for improving Integrated Pest Management (IPM) and Insect Resistance Management (IRM) strategies. In this study, we used stable hydrogen isotopic ratios in wing tissue as a biogeochemical marker to examine migratory patterns and estimate the native origins of H. zea individuals collected across a wide latitudinal gradient in North America. Samples collected at higher latitudes (Ontario, Canada and Minnesota, USA) exhibited a greater proportion (60%-96%) of nonlocal individuals, with an increased probability of origin from the southeastern United States. Populations from mid-latitudes (Florida, North Carolina, and South Carolina) showed a blend of local and nonlocal (40%-60%) individuals. Finally, 15% of the southernmost population individuals (Puerto Rico) were classified as migratory, with some having a probability of origin at higher latitudes (>30°). Overall, our results provide evidence of a northward spring/summer migration of H. zea in North America and underscore the significance of the southeastern United States as a hub for genetic flow. In addition, based on stable hydrogen isotopic ratios, there is strong evidence of reverse (southward) migration of H. zea from the continental United States to Puerto Rico. Our study highlights the implications for IPM and IRM programs and the need for management strategies that account for both northward and southward migration patterns.

Temporal genomics help in deciphering neutral and adaptive patterns in the contemporary evolution of kelp populations

Abstract The impact of climate change on populations will be contingent upon their contemporary adaptive evolution. In this study, we investigated the contemporary evolution of 4 populations of the cold-water kelp Laminaria digitata by analyzing their spatial and temporal genomic variations using ddRAD-sequencing. These populations were sampled from the center to the southern margin of its north-eastern Atlantic distribution at 2 time points, spanning at least 2 generations. Through genome scans for local adaptation at a single time point, we identified candidate loci that showed clinal variation correlated with changes in sea surface temperature (SST) along latitudinal gradients. This finding suggests that SST may drive the adaptive response of these kelp populations, although factors such as species’ demographic history should also be considered. Additionally, we performed a simulation approach to distinguish the effect of selection from genetic drift in allele frequency changes over time. This enabled the detection of loci in the southernmost population that exhibited temporal differentiation beyond what would be expected from genetic drift alone: these are candidate loci which could have evolved under selection over time. In contrast, we did not detect any outlier locus based on temporal differentiation in the population from the North Sea, which also displayed low and decreasing levels of genetic diversity. The diverse evolutionary scenarios observed among populations can be attributed to variations in the prevalence of selection relative to genetic drift across different environments. Therefore, our study highlights the potential of temporal genomics to offer valuable insights into the contemporary evolution of marine foundation species facing climate change.

Poleward migration of tropical corals inhibited by future trends of seawater temperature and calcium carbonate (CaCO3) saturation

Poleward range expansion of marine organisms is commonly attributed to anthropogenic ocean warming. However, the extent to which a single species can migrate poleward remains unclear. In this study, we used molecular data to examine the current distribution of the Pocillopora damicornis species complex in Taiwan waters and applied niche modeling to predict its potential range through the end of the 21st Century. The P. damicornis species complex is widespread across shallow, tropical and subtropical waters of the Indo-Pacific regions. Our results revealed that populations from subtropical nonreefal coral communities are P. damicornis, whose native geographical ranges are approximately between 23°N and 35°N. In contrast, those from tropical reefs are P. acuta. Our analysis of 50 environmental data layers demonstrated that the concentrations of CaCO3 polymorphs had the greatest contributions to the distributions of the two species. Future projections under intermediate shared socioeconomic pathways (SSP) 2–4.5 and very high (SSP5–8.5) scenarios of greenhouse gas emissions showed that while sea surface temperature (SST) isotherms would shift northwards, saturation isolines of two CaCO3 polymorphs, calcite (Ωcal) and aragonite (Ωarag), would shift southwards by 2100. Subsequent predictions of future suitable habitats under those conditions indicated that distinct delimitation of geographical ranges for the two species would persist, and neither would extend beyond its native geographical zones, indicating that tropical Taiwan waters are the northern limit for P. acuta. In contrast, subtropical waters are the southern limit for P. damicornis. We concluded that the decline in CaCO3 saturation would make high latitudes less inhabitable, which could be one of the boundary elements that limit poleward range expansion driven by rising SSTs and preserve the latitudinal diversity gradient (LDG) on Earth. Consequently, poleward migration of tropical reef corals to cope with warming oceans should be reevaluated.

Methane emissions decreased in fossil fuel exploitation and sustainably increased in microbial source sectors during 1990–2020

Methane (CH4) emission reduction to limit warming to 1.5 °C can be tracked by analyzing CH4 concentration and its isotopic composition (δ13C, δD) simultaneously. Based on reconstructions of the temporal trends, latitudinal, and vertical gradient of CH4 and δ13C from 1985 to 2020 using an atmospheric chemistry transport model, we show (1) emission reductions from oil and gas exploitation (ONG) since the 1990s stabilized the atmospheric CH4 growth rate in the late 1990s and early 2000s, and (2) emissions from farmed animals, waste management, and coal mining contributed to the increase in CH4 since 2006. Our findings support neither the increasing ONG emissions reported by the EDGARv6 inventory during 1990–2020 nor the large unconventional emissions increase reported by the GAINSv4 inventory since 2006. Total fossil fuel emissions remained stable from 2000 to 2020, most likely because the decrease in ONG emissions in some regions offset the increase in coal mining emissions in China.

Responses of the coral reef cryptobiome to environmental gradients in the Red Sea.

An essential component of the coral reef animal diversity is the species hidden in crevices within the reef matrix, referred to as the cryptobiome. These organisms play an important role in nutrient cycling and provide an abundant food source for higher trophic levels, yet they have been largely overlooked. Here, we analyzed the distribution patterns of the mobile cryptobiome (>2000 μm) along the latitudinal gradient of the Saudi Arabian coast of the Red Sea. Analysis was conducted based on 54 Autonomous Reef Monitoring Structures. We retrieved a total of 5273 organisms, from which 2583 DNA sequences from the mitochondrially encoded cytochrome c oxidase I were generated through sanger sequencing. We found that the cryptobiome community is variable over short geographical distances within the basin. Regression tree models identified sea surface temperature (SST), percentage cover of hard coral and turf algae as determinant for the number of operational taxonomic units present per Autonomous Reef Monitoring Structures (ARMS). Our results also show that the community structure of the cryptobiome is associated with the energy available (measured as photosynthetic active radiation), sea surface temperature, and nearby reef habitat characteristics (namely hard corals, turf and macroalgae). Given that temperature and reef benthic characteristics affect the cryptobiome, current scenarios of intensive climate change are likely to modify this fundamental biological component of coral reef functioning. However, the trajectory of change is unknow and can be site specific, as for example, diversity is expected to increase above SST of 28.5°C, and with decreasing hard coral and turf cover. This study provides a baseline of the cryptobenthic community prior to major coastal developments in the Red Sea to be used for future biodiversity studies and monitoring projects. It can also contribute to better understand patterns of reef biodiversity in a period where Marine Protected Areas are being discussed in the region.