Talitrus Saltator Research Articles

Ingestion of chitosan-starch blends: Effect on the survival of supralittoral amphipods

Sandy beach ecosystems are particularly affected by plastic pollution. Supralittoral amphipods are important components of the food web in sandy beaches and their ability to ingest microplastics and bioplastics has been assessed. Chitosan, a polysaccharide obtained by deacetylation of chitin, the second most abundant polymer in the world, represents an interesting component to produce novel bioplastics in combination with other biopolymers like starch. Here, the possibility of ingesting chitosan-starch blends and the possible effects on the amphipod Talitrus saltator were investigated. Groups of adult individuals were fed with sheets containing mixtures of chitosan and starch in different percentages for 7 and 14 days. The results showed that chitosan ingestion is dependent on the percentage of starch present in the mixture. Moreover, FTIR analyses of both sheets and faecal pellets after consumption show that chitosan is not digested. Furthermore, the survival rate of amphipods fed with a mixture of chitosan and starch decreases after one week compared to the control groups (100 % starch and paper), and drops drastically to 0 % after two weeks the experiment began. In addition, consumption of 100 % chitosan is negligible. Therefore, the results of the experimental observations evidenced that chitosan is avoided as food resource and its consumption significantly affects the survival capacity of T. saltator. It is emphasized that the release of mixtures of chitosan and starch into the marine environment appears to be dangerous for littoral amphipods.

Potential impacts of titanium dioxide nanoparticles on the biochemical and behavioural status of the amphipods Talitrus saltator (Amphipoda, Talitridae)

ABSTRACT Titanium dioxide nanoparticles (TiO2 NPs) are among the most universally engineered nanomaterials and widely used nanomaterials in the world. In order to predict the environmental impact and interaction between these NPs and coastal organisms, the amphipod Talitrus saltator was exposed to TiO2 NPs C1 = 151.5 µg.L−1 and TiO2 NPs C2 = 303 µg.L−1. Catalase activity increased significantly and reaches a maximum of about 0.8 ± 0.02 µMol/min/mg proteins after exposure to TiO2 NPs C2 showing possible oxidative mechanisms. In addition, acetylcholinesterase activity reduced significantly (p < 0.05) after exposure to the highest TiO2 NPs concentration, indicating neurotransmission disturbance treated with 303 µg.L−1 of TiO2 NPs. Locomotor behaviour for untreated and treated specimens with TiO2 NPs was studied under constant darkness (DD). Results revealed the existence of ultradian and circadian components. In addition, locomotor activity patterns were generally bimodal for untreated specimens and became multimodal for treated ones. We noted also a slippage of the activity peak from the middle of the subjective night for the control until the subjective day after TiO2 NPs exposure. Furthermore, the most important stability was observed for control individuals who were more active than treated ones. Overall, this laboratory study provides preliminary toxicity data for Talitrus saltator exposed to TiO2 NPs.

Artificial light and cloud cover interact to disrupt celestial migrations at night

The growth of human activity and infrastructure has led to an unprecedented rise in the use of Artificial Light at Night (ALAN) with demonstrable impacts on ecological communities and ecosystem services. However, there remains very little information on how ALAN interacts with or obscures light from celestial bodies, which provide vital orientating cues in a number of species. Furthermore, no studies to date have examined how climatic conditions such as cloud cover, known to influence the intensity of skyglow, interact with lunar irradiance and ALAN over the course of a lunar cycle to alter migratory abilities of species.Our night-time field study aimed to establish how lunar phase and climatic conditions (cloud cover) modulate the impact of ALAN on the abundance and migratory behaviour of Talitrus saltator, a key sandy beach detritivore which uses multiple light associated cues during nightly migrations. Our results showed that the number and size of individuals caught decreased significantly as ALAN intensity increased. Additionally, when exposed to ALAN more T. saltator were caught travelling parallel to the shoreline, indicating that the presence of ALAN is inhibiting their ability to navigate along their natural migration route, potentially impacting the distribution of the population. We found that lunar phase and cloud cover play a significant role in modifying the impact of ALAN, highlighting the importance of incorporating natural light cycles and climatic conditions when investigating ALAN impacts. Critically we demonstrate that light levels as low as 3 lx can have substantial effects on coastal invertebrate distributions. Our results provide the first evidence that ALAN impacted celestial migration can lead to changes to the distribution of a species.

The use of polarized light in the zonal orientation of the sandhopper Talitrus saltator (Montagu)

It is well known that the celestial polarization is used as a compass cue by many species of insects and crustaceans. Although it has been shown that the sandhopper Talitrus saltator perceives polarized light and possesses an arrangement of the rhabdomeres that could allow e-vector interpretation and utilization, T. saltator does not use the e-vector of the skylight polarization as a compass cue when making excursions along the sea–land axis of sandy shores. We performed tests in confined conditions to clarify if skylight polarization is somehow involved in the zonal recovery of T. saltator. We observed the directional responses of sandhoppers in a transparent bowl under an artificial sky (an opaline Plexiglas dome). The bowl was covered by a blue gelatin filter with a grey filter (control condition) and a linear polarizing filter (experimental conditions) positioned under the blue one in such a way as to occupy half of the upper surface of the Plexiglas bowl so as to create a linear polarization gradient. Our experiments confirm that T. saltator perceives polarized light and highlight that this visual capability determines the perception, or perhaps the increase, of the radiance and/or spectral gradient and their use as compass cues in the zonal orientation. Moreover, our findings confirm that the radiance gradient is used as a chronometric compass orienting reference in the absence of other celestial orienting cues.

Nutritional composition, heavy metal content and in vitro effect on the human gut microbiota of Talitrus saltator, an underutilized crustacean from the Atlantic coast.

In this study, an undervalued marine crustacean (Talitrus saltator) was characterized in terms of nutritional and heavy metal composition and its potential to affect human gut microbiota. Nutritional analysis of this crustacean revealed that it complies with the criteria established in European legislation to include nutritional claims in their labeling, such as “source of fiber,” “low in fat,” “low in sugars” and “high in protein.” The analysis of the heavy metal content did not reveal any risk derived from the presence of Cd, Hg, or Pb, whereas essential metals contained in 100 g exceeded the minimum daily requirements recommended in Europe for Zn (19.78 mg/kg), Cu (2.28 mg/kg), and Fe (32.96 mg/kg). Using an in vitro system, the effect of T. saltator on the human colonic microbiota shows some beneficial effects, such as fermentation-maintained populations of Bifidobacterium or Lactobacillus, did not increase Firmicutes phylum counts, decreased the Firmicutes/Bacteroidetes ratio, and stimulated 11 metabolic pathways with respect to baseline. These results are unusual in a high protein content-food. However, negative effects were also found in gut microbiota relative proportions, such as an increase in the Proteobacteria phylum and especially some opportunistic bacteria from this phylum, probably due to the antimicrobial effect of chitin on other groups more sensitive to its effect. This work shows for the first time the effect of T. saltator on human colonic microbiota using and in vitro system. The presence of chitin in its composition could provide some beneficial effects by modulating the microbiota, but as T. saltator is a high-protein food, more studies should be carried out showing these benefits.

Body-catapult mechanism of the sandhopper jump and its biomimetic implications

Power amplification with catapult-like structures in arthropods is well studied, including the jump mechanism of natural organisms and biomimetic applications in robotics. Most catapult jump mechanisms have been developed based on animals that use legs to jump. However, jumps of some arthropods that use body parts other than legs and that show outstanding performance have been less studied until now. Here, we experimentally studied the jumping behavior of the sandhopper Talitrus saltator to determine whether they jump through the catapult mechanism and identify its critical catapult structures. The results showed that the sandhopper jumps through a body-catapult mechanism (muscle-specific power output: 1.7–5.7 kW/kg, 3.4–11.4 times the power output limit of arthropod muscle). The arch-shaped structures at the fore margin of the five posterior segments can provide a large amount of strain energy storage and account for more than 80% of the total kinetic energy demand. In addition, we build a biomimetic bi-segment device whose extension movement is actuated by sandhopper-inspired spring units. The results indicate that a multi-segmented robotic configuration can achieve rapid jumps based on the same principles of the body-catapult mechanism of the sandhopper.

Spatio-temporal variation in macrofauna community structure in Mediterranean seagrass wrack

Many Mediterranean beaches accumulate wrack of Posidonia oceanica L. leaves and rhizomes, creating an ecotone between marine and terrestrial systems that provides essential ecosystem services (e.g. shoreline protection, nutrient supply to adjacent dune systems). However, little is still known about the diversity of macrofauna that lives in this wrack and how its community structure varies in space and time. In this study, we assessed the variation in macrofauna composition on three Mallorcan beaches (Balearic Islands, Western Mediterranean Sea) characterized by different geomorphological features. For an entire year, we seasonally sampled P. oceanica wrack on each beach and identified the animal species living in them. We found up to 20 different species belonging to four functional groups: (A) detritivores/fungivores/scavengers, (B) phytophagous, (C) secondary consumers, and (D) tertiary consumers. Species composition and diversity indices showed strong differences among beaches associated with wrack dynamism. Both variables revealed also a significant temporal variation, with highest individual abundance in summer and lowest in winter. Detritivores were the most abundant group, and their contribution to community structure represented over 75% through the study period. Springtails, in particular, contributed the most (45%) to spatial and temporal changes in community structure, followed by the oligochaete Enchytraeus sp. (12.6%) and the sand hopper Talitrus saltator (4.6%). Our study builds towards a more robust understanding of these marine-terrestrial ecotones, demonstrating the existence of complex and dynamic macrofauna communities which can provide more ecological information about the food webs of these ecosystems and the services they provide.

Bayesian predictive model selection in circular random effects models with applications in ecological and environmental studies

In this paper we present a detailed comparison of the prediction error based model selection criteria in circular random effects models. The study is primarily motivated by the need for an understanding of their performance in real life ecological and environmental applications. Prediction errors are based on posterior predictive distributions and the model selection methods are adjusted for the circular manifold. Plug-in estimators of the circular distance parameters are also considered. A Monte Carlo experiment scheme taking the account of various realistic ecological and biological scenarios is designed. We introduced a coefficient that is based on conditional expectations to examine how the deviation from von Mises (vM) distribution, the standard choice in applications, effects the performances. Our results show that the performances of widely used circular predictive model selection criteria mostly depend on the sample size as well as within-sample-correlation. The approaches and selection strategies are then applied to investigate orientational behaviour of Talitrus saltator under the risk of dehydration and direction of wind with respect to associated atmoshperic variables.

Specializations in the compound eye of Talitrus saltator (Crustacea, Amphipoda).

We investigated the eye regionalization in Talitrus saltator by morphological, electrophysiological and behavioural experiments. Each ommatidium possesses five radially arranged retinular cells producing a square fused rhabdom by R1-R4 cells; the smaller R5 exists between R1 and R4. The size of R5 rhabdomere is larger in the dorsal part and becomes smaller in the median and ventral parts of the eye. Spectral-sensitivity by electroretinograms were recorded from dorsal or ventral parts of the eye. The dorsal part possesses maxima at green and UV-blue region. The main response region in the ventral part is only from UV (390nm) to blue (430nm) decreasing at longer wavelengths. To evaluate the sandhoppers' celestial orientation, their eyes were painted black either in the dorsal or ventral part, under the natural sky or a blue filter with or without the vision of the sun. Sandhoppers with the dorsal region of the eyes painted and tested under the screened sun were more dispersed and their directions varied more than in other groups of individuals. Sandhoppers with this area of the eye obscured display considerable difficulties to head in a specific direction. This work suggests the existence of regional specializations in the eye of T. saltator.

A genotoxicity study on Talitrus saltator (Crustacea, Amphipoda) exposed to lead and benzo(a)pyrene

Sandy beaches are ecosystems often subjected to a variety of pollution sources, including heavy metals and polycyclic aromatic hydrocarbons, largely due to improper human activities. The sandhopper Talitrus saltator s. l. (Montagu, 1808) typically lives on supralittoral shores where it plays an important ecological role. The purpose of this study was to investigate DNA damage levels on hemocytes of T. saltator by means of the Comet assay. Firstly, we tested the sensitivity and reproducibility of the Comet assay on hemocytes of T. saltator after in vitro exposure (1 h) to the genotoxicant methyl methanesulfonate (MMS). The data demonstrated a DNA damage (defined as % DNA tail) related to MMS exposure in a concentration-dependent manner. Next, we carried out the assay on hemocytes of T. saltator that were exposed in vivo (24 h and 7 days) to (a) lead (Pb), (b) benzo(a)pyrene (B(a)P), (c) mixtures of them. Our data on exposure to Pb or B(a)P showed DNA damage on the hemocytes of T. saltator in a concentration-dependent manner, but apparently with a non-synergistic effect of exposure to their mixtures. Our results provide a background for further studies in order to verify the applicability of Comet assay on T. saltator for assessing genotoxicity levels in sandy beaches subjected to pollution.

Sky radiance and spectral gradient are orienting cues for the sandhopper Talitrus saltator (Crustacea, Amphipoda).

The sandhopper Talitrus saltator relies on both the sun and the moon compasses to return to the belt of damp sand on the beach in which it lives buried during the day. In addition to the sun, the gradient of radiance and the spectral distribution across the sky could provide directional information that T. saltator can potentially use to orient itself during the day even when the sun is not visible (e.g. cloudy sky). The scope of this work was (1) to determine the intensity levels of sky radiance that the sandhoppers use in their zonal recovery and (2) to investigate whether this species relies on the celestial spectral gradient in its zonal recovery. Sandhoppers were tested in the laboratory under artificial radiance or spectral gradients. Our results show that under an artificial sky simulating the natural radiance gradient on a cloudless day, sandhoppers orientated toward the correct seaward direction of their home beach; however, individuals lost their ability to use the intensity gradient as an orientation cue when the radiance was attenuated by at least 40%. Sandhoppers were also able to head in the correct seaward direction of their home beach at any time of the day by using the spectral gradient as their only source of visual orientation reference.

Friction reduction mechanism of the cuticle surface in the sandhopper talitrus saltator (Amphipoda, talitridae)

In many cases, strong friction reduction is critical for success of both living organisms and engineering systems. Some arthropods exhibit good antifriction abilities in their specific living environments and have inspired many innovations for solving industry challenges. However, the current literature mainly focused on terrestrial insects, such as beetles, grasshoppers and katydids. The antifriction mechanisms in amphibious arthropods are still unknown, even if their surfaces are optimized for both air and water environments. Herein the tribological properties of the cuticle surface of the sandhopper Talitrus saltator were studied using a universal microtribometer. Further investigations were developed to identify the microstructural, compositional, wettability, and mechanical properties of the sandhopper shell cuticles. It was found that increasing normal force can significantly reduce the coefficient of friction of the shell cuticle, especially for the alive and rewet sandhopper shells. The shell consists of bottle-like nano-caves in its exocuticle, nano-tubes in its mesocuticle, and gauze-like multilayers in its endocuticle. Under physiological conditions, glycoprotein-like fluid fillings exist in both the bottle-like caves and the nano-tubes below and cover on the shell surface. More importantly, a new antifriction mechanism of lubricant-squeezing nano-porous system was established for the sandhopper shell. This work can deepen our understanding in antifriction surfaces of amphibiotic crustaceans, and provide a potential approach to resolve the friction challenge in micro-machines, especially for the applications under aqueous condition. Statement of significanceFriction regulation is one of the critical mechanisms for animal locomotion in natural environments. However, not much is known about the mechanism of amphibious arthropods to reduce friction between their body and diverse environments, particularly achieving adaption under both air and aqueous conditions. We quantitatively study the microstructural, compositional and mechanical properties of the sandhopper (Talitrus saltator) shell cuticle and tribological behaviors under different conditions. Our results reveal the nano-porous system with fluid fillings for the sandhopper's shell and demonstrate the potential antifriction mechanism of this amphibious animal. We anticipate this work will inspire some effective antifriction designs for micro-machines, especially for their applications in complex environment like human body.

Talitrus saltator (Montagu, 1808), a species complex (Amphipoda, Senticaudata, Talitroidea, Talitridae).

The frequently studied amphipod genus Talitrus Latreille, 1802, long thought to be monotypic is shown here to include three species. Two species had already been recognized as distinct species. Talitrus cloquetii Audouin, 1826 and T. platycheles Guérin, 1832, but both had long been reduced to synonymy with T. saltator. All three species are described and figured and a key is provided for their identification. Because of the extensive literature associated with the name Talitrus saltator (sensu lato) we have attempted to assign published records to their appropriate species.

Growth of pioneer beach plants is strongly driven by buried macroalgal wrack, whereas macroinvertebrates affect plant nutrient dynamics

Sandy beach food webs depend heavily upon marine organic input, such as macroalgae, as internal organic matter productivity is low. The fate, however, of this marine organic material (termed wrack) after being deposited onto the beach and its relation to pioneer vegetation, consisting of annual and perennial beach plants, needs to be further elucidated. In particular, the effect of various drivers, such as wrack burial and macroinvertebrate presence, on wrack decomposition is largely unknown on sandy beaches. Also, the subsequent effects of decomposition-driven nitrogen and phosphorus availability on beach pioneer plant growth are not yet understood. We performed a mesocosm experiment manipulating Fucus vesiculosus wrack access to the supratidal amphipod Talitrus saltator, and used Cakile maritima and Elytrigia juncea as phytometers to estimate decomposition-driven, wrack-derived nutrient supply. Buried wrack had a strong positive effect (2–3 fold increase) on plant mass, N and P content of C. maritima compared to surface wrack, while effects on E. juncea were largely absent. In addition, macroinvertebrate-facilitated decomposition was important for increasing nutrient availability, but this did not result in an increase in plant growth. We conclude that the burial of wrack by a thin layer of sand is a crucial driver of beach pioneer plant growth, which is most likely due to an increase in moisture availability. This supports the importance of management practices that allow deposited wrack to remain and be buried on the sandy beach for a long period of time, which will have positive effects on beach pioneer plant growth and possibly embryo dune formation.

Distribution and abundance of Talitridae in the southern Baltic Sea – twelve years after the first record of Platorchestia platensis (Krøyer, 1845) in 2005

Abstract Four Talitridae species have been recorded in the southern Baltic Sea, including two indigenous species – Talitrus saltator, Deshayesorchestia deshayesii, and two presumably non-indigenous ones – Cryptorchestia garbinii, Platorchestia platensis. It has been twelve years since Platorchestia platensis was recorded for the first time. The distribution and abundance of talitrids have not been studied since the 1990s. Therefore, the main objective of this research was to document the occurrence in Talitridae in the region in order to determine whether non-indigenous P. platensis has spread and whether it co-occurs with indigenous species. Talitrids were recorded at 20 out of 43 sampling sites. T. saltator occurred both along the coast of the open sea and in the Gulf of Gdańsk. The remaining species were found only around the gulf. P. platensis was more abundant than other species and its density was positively correlated with wrack biomass. Our studies have shown that the area of T. saltator occurrence has decreased during the last two decades. Non-indigenous species P. platensis co-occurred with all other Talitridae species, whereas C. garbinii co-occurred only with P. platensis.

Intra-annual variation of the locomotor behaviour of Talitrus saltator (Amphipoda, Talitridae) from Ghar El Melh

ABSTRACT The seasonal variation of the locomotor activity rhythm of Talitrus saltator was investigated in a population from the supra-littoral zone of the new harbour beach of Ghar El Melh. The rhythm was recorded in individual animals over the four seasons under two simultaneous experimental regimens: the natural light/dark cycle and the continuous darkness. Results revealed that, whatever the season, actograms and mean activity curves showed globally that individuals of T. saltator concentrated their activity during the experimental and subjective day. In addition, specimens exhibited a nocturnal circadian rhythm of locomotor activity with an ultradian component. Under light–dark cycle, circadian periods determined by periodogram analysis in four seasons were appreciably similar and were close to 24 h. Under constant darkness, the circadian period was longer in the autumn (τDD = 1501ʹ.81 ± 56ʹ.2) than the other seasons. In addition, the study of the mean activity times calculated for four seasons showed that the most important activity of individuals was observed in the spring and the autumn under entraining and free-running conditions, respectively.

Microplastics in Talitrus saltator (Crustacea, Amphipoda): new evidence of ingestion from natural contexts.

Using Fourier transform infrared spectroscopy (FT-IR) measurements and comparing the spectrum peaks (range 4000-600cm-1) with reference spectra database and instrument libraries, we observed new evidence of the ingestion of microplastic particles analyzing the digestive tracts of Talitrus saltator. Specimens, sampled in central Italy, probably ingested the particles with natural detritus. Since worldwide many species of invertebrates and vertebrates (e.g., birds) feed on Amphipoda along coastal ecosystems, we hypothesized that microplastic in these crustaceans can be accumulated along the food chain.

Ingested microplastic as a two-way transporter for PBDEs in Talitrus saltator

The presence and accumulation of plastic waste into the marine environment are well known environmental issues. Microplastics (MPs) end up in sea waters and, due to their hydrophobicity and high surface/volume ratio, POPs tend to sorb and accumulate to their surface. The supralittoral amphipod Talitrus saltator (T. saltator) was selected to study the role of MPs in the transfer of organic pollutants and to investigate if ingested MPs could either transfer contaminants to biota or clean it adsorbing pollutants taken from the diet. T. saltator is an established POPs (Persistent Organic Pollutants) biomonitor in coastal environments and it is able to swallow microplastics in natural condition.Two laboratory experiments were performed and T. saltator was exposed to a labelled polybrominated diphenyl ether (13C-labelled BDE-47) to investigate the opposite gradient role of MPs. X Ray Micro-CT (Micro-Computed Tomography) analyses were also performed on sandhopper samples to evaluate the uptake of MPs via digestive tract. The results showed that MPs ingestion could whether transfer and remove contaminants from T. saltator, indicating a partial balance among positive and negative effects. This study has underlined MP potential double role demonstrating that MP can act both as a carrier and scavenger for the bioaccumulation of organic pollutants (i.e. PBDEs), suggesting that chemicals leaching from MPs could have a limited impact to biota.

Locomotor activity rhythm of two sympatric species Talitrus saltator (Amphipoda) and Tylos europaeus (Oniscidea) from Tunisian beaches under continuous light

Locomotor activity rhythm of the supralittoral species Talitrus saltator and Tylos europaeus was studied under continuous light in populations of Korba and Barkoukech beaches in summer. Results showed that these two species were characterized by a nocturnal behaviour. Under the subjective night, the activity was continuous for T. saltator and interrupted in T. europaeus with the presence of a clear drift towards the right more accentuated for the second species. Whatever the site, using actograms and the waveforms, results showed the absence of bimodal profile in T. europaeus and the plurimodal one in T. saltator. Moreover, the most important activity peaks were observed around the dawn and the dusk, respectively. Furthermore, periodogram and MESA analyzes highlighted the presence of ultradian and circadian components. Whatever the component and the site, the inter-individual variability was more pronounced in T. europaeus. Moreover, whatever the site, individuals of T. europaeus were more active and the locomotor rhythm was more defined in T. saltator. With reference to environmental stability and variability, the differences of locomotor activity characteristics observed between these two species are explained as a need for plasticity to adapt to environmental changes.

Effect of light intensity on the locomotor activity rhythm of Talitrus saltator (Montagu 1808) from Korba Beach

ABSTRACTIn this work, we investigate the locomotor behaviour of Talitrus saltator (Montagu 1808) for a population collected from the supralittoral zone of Korba beach. The locomotor activity rhythm was recorded for adult individuals during 10 summer days under continuous light with four different luminous intensities: 5 lux (N = 30), 35 lux (N = 30), 75 lux (N = 30) and 140 lux (N = 15). By the end of the experiments, 100% of the considered individuals were found alive under light intensities of 35 and 140 lux, whereas only 86 and 90% were found alive under light intensity of 5 and 75 lux, respectively. Furthermore, whatever the imposed luminous intensity is, actograms showed a clear drift to the right lengthening day after day the circadian period. Moreover, we found that by raising the light intensity, the drift becomes increasingly important. Actograms as well as activity curves, results showed that the locomotor activity profiles are mainly unimodal and their percentage increases when increasing the light intensity. Furthermore, periodogram analysis highlighted the presence of ultradian and circadian components where the longest periods were observed with the highest luminous intensity. In addition, the locomotor activity rhythm was statistically more defined and individuals of Talitrus saltator were significantly more active under the lowest luminous intensity.