Multiple climate-driven cascading ecosystem effects after the loss of a foundation species.

Climate change is evolving so fast that the related adverse effects on the environment are becoming noticeable. Thus, there is an urgent need to explore and understand the effects generated by multiple extreme climatic events (MECEs) on marine ecosystem functioning and the services provided. Accordingly, we combined long-term in-situ empirical observations in the Mediterranean Sea with a mesocosm manipulation to investigate the concurrence of increasing temperature and hypoxia events. By focussing on a foundation mussel species, we were able to detect several cascade events triggered by a mass mortality event caused by stressful temperature and oxygen conditions, and resulting in a loss of ecosystem services. The measured rates of chlorophyll-a, carbohydrates, proteins and lipids - in both particulate and sedimentary organic matter - were used as proxies of ecosystem functioning during pre- and post- disturbance events (MECEs). In the past, MECEs were crucial for individual performance, mussel population dynamics and biomass. Their effect propagated along the ecological hierarchy negatively affecting the associated community and ecosystem. Our results suggest that the protection and/or restoration of coastal areas requires careful consideration of ecosystem functioning. SIGNIFICANCE STATEMENT: Our decadal time-series recorded by a near-term ecological forecasting network of thermal sensor allowed us to record and monitor multiple extreme climatic events (MECEs; heat wave and hypoxia events), warning on the environmental change recorded on a pond system. By integrating observational and manipulative approaches, we showed how a MECE triggered cascade events, from individual-based impaired functioning up to biodiversity loss (community composition and structure changes). Our results emphasize the key role played by a foundation species in driving ecosystem functioning, and the synergistic effects of climatic drivers acting simultaneously.

Beyond virology: environmental constraints of the first wave of COVID-19 cases in Italy.

Global warming and air pollution affect the transmission pathway and the survival of viruses, altering the human immune system as well. The first wave of the COVID-19 pandemic dramatically highlights the key roles of climate and air chemistry in viral epidemics. The elongated form of the Italian peninsula and the two major islands (the largest in Europe) is a perfect case study to assess some of these key roles, as the fate of the virus is mirroring the industrialization in the continental part of our country. Fine particulate matter (PM2.5), geography, and climate explain what is happening in Italy and support cleaner air actions to address efficiently other outbreaks. Besides the environmental factors, future works should also address the genetic difference among individuals to explain the spatial variability of the human response to viral infections.

Testing for top-down cascading effects in a biomass-driven ecological network of soil invertebrates.

To investigate the structural changes of a food-web architecture, we considered real data coming from a soil food web in one abandoned pasture with former low-pressure agriculture management and we reproduced the corresponding ecological network within a multi-agent fully programmable modeling environment in order to simulate dynamically the cascading effects due to the removal of entire functional guilds.We performed several simulations differing from each other for the functional implications. At the first trophic level, we simulated a removal of the prey, that is, herbivores and microbivores, while at the second trophic level, we simulated a removal of the predators, that is, omnivores and carnivores. The five main guilds were removed either separately or in combination.The alteration in the food-web architecture induced by the removal of entire functional guilds was the highest when the entire second trophic level was removed, while the removal of all microbivores caused an alteration in the food-web structure of less than 5% of the total changes due to the removal of opportunistic and predatory species.Omnivores alone account for the highest shifts in time of the numerical abundances of the remaining species, providing computational evidence of the importance of the degree of omnivory in the stabilization of soil biota.

Novel Amino Acid Assembly in the Silk Tubes of Arid-Adapted Segestriid Spiders.

We investigated in different sites inside or outside the Namib Desert the amino acids composition of the protein material forming the tube silk of Ariadna spiders. These spiders belong to the primitive Segestriidae family and spend their life inside vertical silk burrows dug within the sandy and gravelly soil of arid areas. The silks, previously purified by solubilization in hexafluoroisopropanol, were subjected to partial or total acid hydrolysis. Partial hydrolyzed samples, analyzed by mass spectrometry (matrix assisted laser desorption/ionization and electrospray), led to relevant information on the amino acid sequences in the proteins. The free amino acids formed by complete hydrolysis were derivatized with the Marfey's reagent and characterized by electrospray mass spectrometry. The reconstruction of the amino acids highlights a homogeneous plan in the chemical structure of all the analyzed silks. Eight amino acids constituting the primary structure of the proteins were identified. Alanine and glycine are the most abundant ones, with a prevalence of alanine, constituting together at least 61% of the chemical composition of the protein material, differently from what occurs in known spidroins. High percentages of proline, serine and threonine and low percentages of leucine complete the peculiarity of these proteins. The purified silks were also characterized by Fourier-transform Infrared Spectroscopy and their thermal properties were investigated by differential scanning calorimetry. The comparison of the silk tubes among the various Namibian populations, carried out through a multivariate statistical analysis, shows significant differences in their amino acid assembly possibly due to habitat features.

Lymph node ratio and liver metachronous metastases in colorectal cancer.

AIM: The authors seek to assess whether the lymph node ratio (the ratio of positive nodes divided by the total number of retrieved nodes) could predict the risk of metachronous liver metastases. MATERIAL AND METHODS: A homogeneous group of 280 patients, followed-up for at least 5 years, was evaluated. In order to highlight the groups with the highest risk of metachronous liver metastases, patients were divided into four quartiles groups in relation to the LNR. RESULTS: The number of lymph nodes sampled in group "stage I" was significantly lower. Even if statistical significance between the global LNR and the development of liver metastases has not been reached, the subdivision into quartiles has made it possible to highlight that in the more advanced ratio groups, a higher incidence of metachronous liver metastases (p <0.028) was registered and was a different distribution of patients with or without liver metastasis in function of quartiles (P =0.01). DISCUSSION: The LNR has enabled us to prognosticate patients who are at greater risk of developing metachronous liver metastases. The lower lymph node sampling in the patients with less advanced staging (I) and in patients with nodenegative cancer (I+II) who developed liver metastases, leads us to believe that some patients have been understaged. CONCLUSION: We believe that the LNR, especially in cases of adequate lymph node sampling, is a useful gauge to better sub-stratify "node-positive" patients. KEY WORDS: Colorectal cancer, Liver metastases, Lymph node ratio.

Predator traits determine food-web architecture across ecosystems.

Predator-prey interactions in natural ecosystems generate complex food webs that have a simple universal body-size architecture where predators are systematically larger than their prey. Food-web theory shows that the highest predator-prey body-mass ratios found in natural food webs may be especially important because they create weak interactions with slow dynamics that stabilize communities against perturbations and maintain ecosystem functioning. Identifying these vital interactions in real communities typically requires arduous identification of interactions in complex food webs. Here, we overcome this obstacle by developing predator-trait models to predict average body-mass ratios based on a database comprising 290 food webs from freshwater, marine and terrestrial ecosystems across all continents. We analysed how species traits constrain body-size architecture by changing the slope of the predator-prey body-mass scaling. Across ecosystems, we found high body-mass ratios for predator groups with specific trait combinations including (1) small vertebrates and (2) large swimming or flying predators. Including the metabolic and movement types of predators increased the accuracy of predicting which species are engaged in high body-mass ratio interactions. We demonstrate that species traits explain striking patterns in the body-size architecture of natural food webs that underpin the stability and functioning of ecosystems, paving the way for community-level management of the most complex natural ecosystems.

How soil granulometry, temperature, and water predict genetic differentiation in Namibian spiders (Ariadna: Segestriidae) and explain their behavior.

The Namib Desert is a biodiversity hotspot for many invertebrates, including spiders. Tube-dwelling spiders belonging to the Ariadna genus are widespread in gravel plains. These sit-and-wait predators share a particular behavior, as they spend their life in tunnels in the soil, surrounding the entrance of their burrow with stone rings. We investigated five spider populations taking into account environmental parameters, functional traits, and molecular data. We have chosen the temperature at the soil surface and at the bottom of the burrow, the air humidity, and the soil granulometry to define the environment. The chosen functional traits were the diameter and depth of the burrows, the ratio between weight and length, the thermal properties of their silks, and the number of ring elements. The molecular branch lengths and the evolutionary distance emerging from cytochrome oxidase I gene sequences summarized the molecular analysis. Our study highlights a strong coherence between the resulting evolutionary lineages and the respective geographical distribution. Multivariate analyses of both environmental and molecular data provide the same phylogenetic interpretation. Low intrapopulation sequence divergence and the high values between population sequence divergence (between 4.9% and 26.1%) might even suggest novel taxa which deserve further investigation. We conclude that both the Kimura distance and the branch lengths are strengthening the environmental clustering of these peculiar sites in Namibia.

Orientation behavior is a good biomarker of trace metal contamination in Parallelomorphus laevigatus (Coleoptera, Carabidae).

Behavioral ecotoxicology has become very important in the short time since a change in behavior is very often the first response to environmental altered conditions. We investigated the influence of trace metal intake on the spatial orientation performances of the carabid beetle Parallelomorphus laevigatus, fundamental ability for its survival. The aim of this study was to consider the solar orientation as behavioral biomarker for exposure to trace metal contamination. Therefore, we tested the ability of solar orientation of specimens of this species, fed with shrimps contaminated with three different concentrations of Cu, Zn, or Hg. We carried out the orientation tests after 1, 3, 7, and 10 days of contaminated feeding. Subsequently, we fed these beetles with not contaminated shrimps and again tested them after 1, 3, 7, and 10 days. For all three metals considered and, regardless of the degree of contamination of the food, we have found a progressive and significant counterclockwise displacement of the angle of orientation and a corresponding progressive reduction in the precision in the directional choices by the animals. We also noticed a clear growing recovery in the normal orientation by these insects after returning to their feeding with uncontaminated food. In conclusion, we can consider the orientation in space of P. laevigatus as a behavioral biomarker for exposure to trace metal contamination. We believe that the intake of trace metals may induce the insects to make mistakes in their spatial orientation, due to an acceleration of their biological clock. Such a clock malfunction is not definitive, since the return to a normal diet restores P. laevigatus the ability to re-make the correct directional choices. Ultimately, our results confirm the usefulness of behavioral ecotoxicology investigations; moreover, they stimulate the opportunity to deepen the understanding of functioning of the biological clock in the animals.

The ground beetle Parallelomorphus laevigatus is a potential indicator of trace metal contamination on the eastern coast of Sicily.

Carabids are generally considered to be non-specialized predators, and they have been considered useful ecological indicators. They can play a key role in clarifying the route of contaminants in food webs because they are predators of small invertebrates and, in turn, part of the diet of several vertebrates. The Mediterranean species Parallelomorphus laevigatus, which so far has not been studied from an ecotoxicological point of view, is an excellent ecological indicator in sandy coastal environments. We investigated the accumulation of trace elements in Ionian populations of P. laevigatus and evaluated the transfer of metal through the food chain of the coastal ecosystem. We analyzed 15 metals, including 11 essential metals (Co, Cr, Cu, Fe, Mn, Mo, Ni, Se, Sn, V and Zn) and four toxic metals (As, Cd, Hg and Pb). Significant differences were found in metal concentration in animal tissues among sites. Our results support the existence of defense mechanisms for the studied species. High values of As, Cd, Cr, Pb, Ni, and Hg detected in the beetles from the control site can be explained by both the emission sources from the nearby industrial plants and the intense agricultural activity. The present paper shows increasing Hg concentrations in the simplified trophic web of sandy beaches and confirms the capability of this pollutant to biomagnify. Moreover, the high value of biomagnification factor (BMF) points to the severe pollution level in this protected area.

Bioaccumulation of trace elements in the sandhopper Talitrus saltator (Montagu) from the Ionian sandy coasts of Sicily.

The Ionian beaches of Sicily are of particular ecological interest because they include the basin of the largest active volcano in Europe and hosts both sites subject to natural protection constraints, as well as important industrial settlements. Consequently, the possibilities for these areas to become polluted are numerous. The sandhopper Talitrus saltator has proven to be a good bioindicator of contamination by numerous trace metals on some European coasts. Nevertheless, no data are available for the populations inhabiting the shores of the southern Mediterranean. Now, as metal accumulation has been shown to vary intraspecifically, the aim of this study was to evaluate trace metal accumulation in adults of T. saltator inhabiting Ionian coastal areas of Sicily and make an assessment of natural and anthropogenic metal pollution of this strip of coast. We also extended our survey to As, Co, Mo, Se, Sn and V never investigated before in this species. Significant differences in metal concentration among sites were found in both sand samples and amphipod tissues. The highest metal content was observed near the mouth of Simeto, the longest river of Sicily which collects waters coming from the volcanic territory of Mount Etna. The bioaccumulation of Cd, Cu, Hg and Zn in T. saltator is fully confirmed; it is also proven for As and Mo and assumed for Cr, Fe, Mn and V. Our outcomes let us to evaluate the prevailing influence of telluric contamination of the Ionian sandy shores of Sicily by trace metals. We also come to the conclusion that in the northern sites, pollution originates from volcanic emission while anthropogenic influence prevails in the southern ones.