Littorina Littorea Research Articles

Mechanistic insights into uptake, transfer and exchange of metal ions by the three-metal clusters of a metalloprotein.

Metallothioneins (MTs) are small proteins that coordinate d-block metal ions in sulfur-metal clusters to control metal ion concentrations within the cell. Here we study metal cluster formation in the MT of the periwinkle Littorina littorea (LlMT) by nuclear magnetic resonance (NMR). We demonstrate that the three Cd2+ ions in each domain are taken up highly cooperatively, that is, in an all-or-none fashion, with a four- to six-fold higher affinity for the C-terminal domain. During the transfer of metal ions from Cd2+-loaded MT to apo MT, Cd2+ is most efficiently transferred from the metalated protein to the apo C-terminal domain. This behavior might be connected to unique structural motifs in the C-terminal domain, such as two double-CXC motifs and an increased proportion of positively charged residues. In Cd2+/Zn2+ metal exchange experiments, the N-terminal domain displayed the most efficient inter-molecular metal exchange. Amide hydrogen exchange reveals fewer protected amides for the N-terminal domain, suggesting the structure might more easily "open up" to facilitate metal exchange. Experiments with a physical separation of donor and acceptor species demonstrate that metal exchange and transfer require protein-protein contacts. These findings provide insights into the mechanism of metal uptake and metal transfer, which are important processes during metal detoxification in snail MTs.

Ecological observations of freshwater snails in the vicinity of an artificial lake

This investigation delves into the ecological dimensions of freshwater snails in the vicinity of an artificially created lake. The aim of this research was to comprehend the distribution, prevalence, and variety of freshwater snail species within the ecosystem surrounding the manmade lake. The study spanned from August to November 2023, conducted at three distinct sample stations (I, II, and III), with bi-weekly sample collections. Standard keys were employed for the identification of snails, and the Shanon-Weiner and Simpson's similarity indices were used to explore the diversity of snail species. Throughout the study, a total of 311 individuals representing three distinct species encountered in this study were documented. Acathina fulica exhibited the highest abundance (129 individuals), while Pomacea bridgesii displayed the lowest abundance (66 individuals). The month of August registered the highest population (122 individuals), contrasting with the lowest count in November (37 individuals). Abundance varied across stations, with Station II recording the lowest (77 individuals) and Station III the highest (116 individuals). Regarding diversity, Pomacea bridgesii emerged as the most diverse species (0.3670 & 0.3662), while Littorina littorea exhibited the least diversity (0.0000) across the stations. This investigation contributes valuable insights into the dynamics of freshwater snail populations in the periphery of artificial lakes, shedding light on their distribution patterns and ecological interactions.

Effect of trematode infection on cardiac activity of marine gastropod Littorina littorea in situ and under laboratory conditions.

Physiological mechanisms underlying relationships between the trematode parthenitae and their molluscan hosts are poorly understood. In this study, we estimated the cardiac function of gastropods Littorina littorea L. infected with Himasthla elongata and Cryptocotyle lingua under laboratory conditions and in situ. The heart rate (HR) of the infected periwinkles was significantly lower than in the uninfected ones. HR of uninfected periwinkles in the natural environment followed a clear tidal pattern, with high values at high tide and low values at low tide. However, HR in most of the infected molluscs did not follow this rhythm. The decrease in HR was more pronounced in the periwinkles infected with C. lingua than with H. elongata. Thus, infection with C. lingua had a greater effect on the physiology and metabolic rate of periwinkles than infection with H. elongata.

The Impacts of the Multispecies Approach to Caffeine on Marine Invertebrates.

Caffeine is one of the most consumed substances by humans through foodstuffs (coffee, tea, drugs, etc.). Its human consumption releases a high quantity of caffeine into the hydrological network. Thus, caffeine is now considered an emergent pollutant sometimes found at high concentrations in oceans and seas. Surprisingly, little research has been conducted on the molecular responses induced by caffeine in marine organisms. We studied, in laboratory conditions, six phylogenetically distant species that perform distinct ecological functions (Actinia equina and Aulactinia verrucosa (cnidarians, predator), Littorina littorea (gastropod, grazer), Magallana gigas (bivalve, filter-feeder), and Carcinus maenas and Pachygrapsus marmoratus (crabs, predator and scavenger)) subjected to caffeine exposure. The antioxidant responses (catalase, CAT; glutathione peroxidase, GPx; superoxide dismutase, SOD), lipid peroxidation (MDA), and the acetylcholinesterase (AChE) activity were estimated when the organisms were exposed to environmental caffeine concentrations (5 μg/L (low), 10 μg/L (high)) over 14 days. Differential levels of responses and caffeine effects were noted in the marine invertebrates, probably in relation to their capacity to metabolization the pollutant. Surprisingly, the filter feeder (M. gigas, oyster) did not show enzymatic responses or lipid peroxidation for the two caffeine concentrations tested. The marine gastropod (grazer) appeared to be more impacted by caffeine, with an increase in activities for all antioxidative enzymes (CAT, GPx, SOD). In parallel, the two cnidarians and two crabs were less affected by the caffeine contaminations. However, caffeine was revealed as a neurotoxic agent to all species studied, inducing high inhibition of AChE activity. This study provides new insights into the sublethal impacts of caffeine at environmentally relevant concentrations in marine invertebrates.

Olivine avoidance behaviour by marine gastropods (Littorina littorea L.) and amphipods (Gammarus locusta L.) within the context of ocean alkalinity enhancement

Gigaton scale atmospheric carbon dioxide (CO2) removal (CDR) is needed to keep global warming below 1.5 °C. Coastal enhanced olivine weathering is a CDR technique that could be implemented in coastal management programmes, but its CO2 sequestration potential and environmental safety remain uncertain. Large scale olivine spreading would change the surficial sediment characteristics, which could potentially reduce habitat suitability and ultimately result in community composition changes. To test this hypothesis, we investigated the avoidance response of the marine gastropod Littorina littorea (Linnaeus, 1758) and marine amphipod Gammarus locusta (Linnaeus, 1758) to relatively coarse (83 – 332 µm) olivine and olivine-sediment mixtures during short-term choice experiments. Pure olivine was significantly avoided by both species, while no significant avoidance was observed for sediment with 3% or 30% w/w olivine. For L. littorea, aversion of the light green colour of pure olivine (i.e. positive scototaxis) was the main reason for avoidance. Moreover, olivine was not significantly avoided when it was 7.5 cm (45%) closer to a food source/darker microhabitat (Ulva sp.) compared to natural sediment. It is inferred that the amphipod G. locusta avoided pure olivine to reduce Ni and Cr exposure. Yet, a significant increase in whole body Ni concentrations was observed after 79 h of exposure in the 30% and 100% w/w olivine treatments compared to the sediment control, likely as a result of waterborne Ni uptake. Overall, our results are significant for ecological risk assessment of coastal enhanced olivine weathering as they show that L. littorea and G. locusta will not avoid sediments with up to 30% w/w relatively coarse olivine added and that the degree of olivine avoidance is dependent on local environmental factors (e.g. food or shelter availability).

Seasonal Variations in Heavy Metal Content of Periwinkle Samples obtained from Oil Producing Communities within Bayelsa State, Nigeria

The effects of seasonal variations on the heavy metal content of periwinkle (Littorina littorea) were investigated. Samples were obtained from five stations within the oil producing communities of Bayelsa State, Nigeria. The standard digestion method was used to determine the levels of zinc, lead, nickel, copper, cadmium and chromium with the aid of the atomic absorption spectrophotometer (AAS). (Cadmium (0.216 – 0.727 ppm) and chromium (0.003 – 0.110 ppm) were significantly higher. Zinc, lead, nickel and copper were below the minimum permissible limits. Results obtained for chromium was significant at p(0.05) for the Pearson correlation coefficient. Oil production increases the concentration of heavy metals in water causing harmful to living and non-living resources. Further studies within the study area will assist in effective monitoring of the environment for sustainable development.

Tissue Distributions and Toxic Effects of Hexavalent Chromium in Laboratory-Exposed Periwinkle (Littorina littorea Linnaeus).

The increased use of hexavalent chromium (Cr6+) in various industrial applications has contributed to its elevated levels in the environment, especially the aquatic environment. Thus, there is the potential for accumulation of Cr6+ in the tissues of aquatic organisms and consequent toxic effects. The toxic effects of Cr6+ in aquatic organisms have been widely reported; however, little is known about the patterns of tissue accumulation of Cr6+ and its toxicity in aquatic mollusks. Thus, the present study investigated the effects of Cr6+ exposure on the tissue distribution, proximate composition, and histopathology of an aquatic mollusk, periwinkle (Littorina littorea). The animals were exposed to sublethal concentrations of Cr6+ (0.42, 0.84, and 4.2 mg/L) for 30 days, after which the condition index, tissue accumulation, proximate composition, and histopathological effects were determined. The control animals were maintained in a medium that did not contain Cr6+ (0 mg/L). The condition index did not differ significantly among the groups. The levels of Cr6+ in the tissues differed significantly among the different tissue types while there was no significant effect of the exposure concentration, except in the foot tissue. The proximate parameters (protein, carbohydrates, lipid, crude fiber, and moisture contents) differed significantly among the groups. The protein contents of the exposed animals were significantly lower than those of the control animals and the histological architecture of the major organs was altered in the chromium-exposed animals. The findings from this study indicate a low potential of L. littorea to bioaccumulate Cr6+ in its tissues at the low exposure concentrations tested in this study; as such, its consumption may not pose any serious health risks to humans. However, changes in the proximate composition and histological architecture of the exposed L. littorea show that Cr6+ is potentially toxic to periwinkles.

Unveiling novel RNA viruses in trematodes parasitizing common periwinkle: Implications for host-parasite interactions

This study characterized novel RNA viruses, parasites of parasites, or hyperparasites identified during transcriptomic analyses of two trematode species, Cryptocotyle lingua and Himasthla elongata, infecting a sea snail, Littorina littorea. According to the viral genome structures and phylogenetic analysis, Cryptolin alternavirus (ClRNAV1), Cryptolin calicivirus (ClRNAV2) and Himastelon rhabdovirus 1 (HeRNAV1) were respectively classified within the families Alternaviridae, Caliciviridae and Rhabdoviridae. They replicate species-specifically in two studied phases of trematode live cycle: intramolluscan parthenogenetic rediae and free-swimming cercariae. ClRNAV1 showed significantly higher expression in C. lingua cercariae relative to rediae. HeRNAV1′s similarity to rabies viruses raises questions about its potential effects on the nervous system of H. elongata. This 'trematode rabies' could enable the use of genetically modified viruses for developing new methods to control the spread and intensity of diseases caused by trematodes.

Ecology and environmental characteristics influence methylmercury bioaccumulation in coastal invertebrates

Quantifying mercury (Hg) concentrations in invertebrates is fundamental to determining risk for bioaccumulation in higher trophic level organisms in coastal food webs. Bioaccumulation is influenced by local mercury concentrations, site geochemistry, individual feeding ecologies, and trophic position. We sampled seven species of invertebrates from five coastal sites in the Minas Basin, Bay of Fundy, and determined body concentrations of methylmercury (MeHg), total mercury (THg), and stable isotopes of nitrogen (δ15N) and carbon (δ13C). To evaluate the effects of environmental chemistry on Hg production and bioaccumulation, bulk sediments from all sites were analysed for THg, %Loss on ignition (LOI) (carbon), and sulfur isotopes (δ34S), and concentrations of MeHg, Total Organic Carbon (TOC), sulfate, and sulfide were measured in porewaters. The mean concentration of MeHg in tissues for all invertebrates sampled was 10.03 ± 7.04 ng g−1). MeHg in porewater (mean = 0.22–1.59 ng L−1) was the strongest predictor of invertebrate MeHg, but sediment δ34S (−0.80–14.1‰) was also a relatively strong predictor. δ34S in tissues (measured in three species; Corophium volutator, Ilyanassa obsoleta, and Littorina littorea) were positively related to MeHg in invertebrates (r = 0.55, 0.22, and 0.71 respectively), and when used in combination with δ15N and δ13C values improved predictions of Hg concentrations in biota. Hg concentrations in the amphipod Corophium volutator (mean MeHg = 10.60 ± 1.90 ng g−1) were particularly well predicted using porewater and sediment chemistry, highlighting this species as a useful bioindicator of Hg contamination in sediments of the Bay of Fundy.

Investigating the impact of introduced crabs on the distribution and morphology of littorinid snails: Implications for the survival of the snail Littorina saxatilis

Introduced species can have profound impacts on communities by displacing and consuming native organisms. The intertidal communities in the Gulf of Maine have been radically altered through a suite of invasions in the early 1800s, including the herbivorous snail Littorina littorea and the omnivorous European green crab Carcinus maenas leading to morphological and distributional changes in two native gastropod grazers (Littorina saxatilis and Littorina obtusata). Green crabs and native cancrid crabs occupy the mid to low intertidal zones, leaving the high intertidal zones relatively free from crab predation pressure. However, a more recent invasion in the 1980s by the intertidal omnivorous Asian shore crab Hemigrapsus sanguineus, has eliminated this predator-free zone in the high intertidal. This invasion is of particular concern to populations of L. saxatilis, which were relegated to the high intertidal through combined competition and predation pressure by L. littorea and C. maenas. In order to quantify the potential impact of H. sanguineus on native snails, we conducted both field and lab experiments, testing the susceptibility of different sized snails to predation by introduced crabs. Additionally, we measured the distribution, abundance, and morphology of intertidal snails and crabs. Smaller snails of all species were the most susceptible to predation, although susceptibility differed among snail species and predation capabilities differed among crab species. L. saxatilis was the most vulnerable snail species to predation, with 73 and 64% of the population susceptible to large H. sanguineus and small C. maenas, respectively, while >96% of the L. littorea population was resistant to predation. L. saxatilis has been relegated to the high intertidal where there is high abiotic stress and poor-quality food, but until the invasion of H. sanguineus, there was little predation risk. This added predation pressure may further threaten populations of L. saxatilis, especially as the upper intertidal becomes more hostile with increasing temperatures and possible species introductions.

Effects of temperature, salinity and diet on embryonic and early larval development in Littorina littorea (Gastropoda: Littorinimorpha)

IntroductionThe common periwinkle Littorina littorea is a delicacy in southern Europe. Enabling aquaculture production would be measure to avoid future over-harvesting and ensure a constant market supply.MethodsHowever, knowledge gaps in reproductive biology needs to be filled to allow setting up rearing protocols.ResultsWe investigated effects of temperature and salinity on embryonic development by incubating eggs at ten different temperatures in steps every 2°C, form 5 to 23°C) and four salinities (20 – 40). Embryonic development was clearly temperature dependent; eggs hatched after three days at the highest temperature while it took 16 days to hatch at the lowest temperature. Calculating effective day-degrees (DDeff) allowed expressing the thermal history of the embryogenesis and concluding that this species hatches on average at 61 (SD 3.7) DDeff. Larval growth- and developmental rates showed a different response to the temperature extremes as snails with the smallest shell lengths at hatch were found for the highest and lowest temperatures (204.5, SD = 11.6, and 202.9µm, SD = 13.7 respectively). Viable larvae only hatched at temperatures above 9°C. Larvae hatched at lower temperatures did not develop a shell or swimming lobes. Salinity and temperature significantly influenced time-to-hatch and hatching success; the lowest salinity (20PSU) lead to later hatching (80-100DDeff) and lower hatching success compared to higher salinities (25, 30, and 40, hatch around 40-50 DDeff). Neither hatch rate nor time-to-hatch showed differences among the higher salinities, suggesting a salinity threshold below 25. There was no significant interaction between salinity and temperature on time-to-hatch or hatching success. Larval diet had a significant effect on growth rates during the planktonic stage. Veliger larvae fed on two different live microalgae mono-diets (Dunaliella tertiolecta and Rhodomonas baltica) successfully passed their pelagic phase at the same time with no differences in growth rates, while veliger larvae fed on either of two preserved microalgae products (Nannochloropis sp. and Tetrasemis sp. frozen pastes) were not growing.DiscussionWe conclude that embryonal development can be successfully completed at temperatures between 7 and 20°C, while lower or higher temperatures should be avoided. Successfully hatched larvae can be fed on mono-microalgae diets until settlement.

Effect of electromagnetic fields from renewable energy subsea power cables on righting reflex and physiological response of coastal invertebrates

Offshore renewables are expanding, yet more information is required to understand their possible impacts on the environment. Little is known about the effects of Electromagnetic Fields (EMF) from subsea power cables on marine life. This study simulated an EMF of 500 μT, as modelled for an export cable over a rocky shore, where the industry standard cable burial would not be possible. Righting reflex, refractive index of haemolymph/coelomic fluid, and total haemocyte/coelomocyte counts were measured for four coastal invertebrates (Asterias rubens, Echinus esculentus, Necora puber, and Littorina littorea). No significant differences were found in either behavioural or physiological responses. This was the first study to investigate EMF exposure on righting reflex, and the first ever EMF study on edible sea urchins and periwinkles, and only one of a couple for common starfish and velvet crabs. It therefore, provides valuable data for environmental impact assessments, marine spatial planning, and commercial fisheries.

A MASP-like functions as PRR to regulate the mRNA expressions of inflammatory factors in the Pacific oyster Crassostrea gigas.

Mannose-binding lectin-associated serine protease (MASP) is a type of central serine protease in the complement lectin pathway. In the present study, a MASP-like was identified from the Pacific oyster Crassostrea gigas, defined as CgMASPL-2. The cDNA sequence of CgMASPL-2 was of 3399 bp with an open reading frame of 2757 bp and encoded a polypeptide of 918 amino acids containing three CUB domains, an EGF domain, two IG domains, and a Tryp_SPC domain. In the phylogenetic tree, CgMASPL-2 was firstly clustered with Mytilus californianus McMASP-2-like, and then assigned into the invertebrate branch. CgMASPL-2 shared similar domains with M. californianus McMASP-2-like and Littorina littorea LlMReM1. CgMASPL-2 mRNA was expressed in all the tested tissues with the highest expression in haemolymph. CgMASPL-2 protein was mainly distributed in the cytoplasm of haemocytes. The mRNA expression of CgMASPL-2 increased significantly in haemocytes after Vibrio splendidus stimulation. The recombinant 3 × CUB-EGF domains of CgMASPL-2 displayed binding activities to diverse polysaccharides (lipopolysaccharide, peptidoglycan and mannose) and microbes (Staphylococcus aureus, Micrococcus luteus, Pichia pastoris, Vibrio anguillarum, V. splendidus and Escherichia coli). In anti-CgMASPL-2 treated oysters, the mRNA expressions of CgIL17-1 and CgIL17-2 in haemocytes decreased significantly after V. splendidus stimulation. The results indicated that CgMASPL-2 could directly sense microbes and regulate the mRNA expressions of inflammatory factors.

Population Dynamics of Intertidal Resident Species during a Reduction in Asian Shore Crab Population

Hemigrapsus sanguineus (Asian shore crab), which is native to coastal estuarine habitats along the east coast of Asia, have overtaken a wide range of the coast in the northeastern region of the United States. Intertidal population densities of Hemigrapsus sanguineus, Cancer irroratus (Atlantic rock crab), Littorina littorea (Common periwinkle), and Modiolus demissus (Atlantic Ribbed Mussel), among others, were measured at three sample sites from 8/2/22 to 11/14/22 using quadrat sampling techniques. A period of removal was enacted solely upon Sample site #1 from 9/28/22 to 11/2/22 to cause a reduction in the Asian shore crab population. During the period of removal, no statistically significant changes in Asian shore crab demographics (Carapace size/sex ratios) would be observed (p = 0.181 for carapace size changes). There would however be an 8% decrease in Asian shore crab population density within Sample site #1, comparative to a 1% increase at Sample site 2. Rock crab population density at Sample site #1 would increase by a relatively drastic 31%, whereas the Rock crab population would experience only a 7% increase at Sample site #2. The Shannon-Weiner diversity index was used to derive the effective number of species (ENS). There would be a drastic difference in change of ENS following the removal period at Sample site #1 (increase of 0.248 ENS), and the change of ENS at Sample site #2 (decrease of 0.024 ENS), suggesting the reduction in Asian Shore Crab population played a role in increased population diversity of intertidal resident species.

Traditional food consumption pattern and nutritional status of Oraons: An Asian Indian indigenous community

IntroductionFood consumption is an intensive social activity and can be considered a cultural artifact, reflecting the intricate process of sociocultural differentiation in shaping eating habits. Food has a positive effect on a person's health, physical performance, and state of mind. The nutritional composition of a person's diet plays a significant role in their overall health and development. Moreover, tribal cuisine is incomplete without a traditional drink. Rice beer, or handia, is one such indigenous alcoholic-fermented beverage that serves as a staple food.MethodsThis exploratory cross-sectional study was conducted from January, 2018 to December, 2020 to explore the traditional food practices of the Oraon community through a combination of one-to-one interviews, focus group discussions, and measurements. This study also involved the documentation of individual food recipes, from collection to preparation. To assess nutrient intake, we used a 24-h dietary recall method for 200 Oraon families comprising 466 adults and 193 children. Anthropometric measurements, such as body mass index (BMI) for adults and height-for-age and BMI-for-age z-score methods for children, recommended by the WHO, were taken and recorded using standard procedures. Additionally, the nutrient content of handia was analyzed.ResultsThe mean (SD) height, weight, mid-upper arm circumference (MUAC), and BMI of the Oraon people were analyzed. The combined overall prevalence of chronic energy deficiency (CED) (BMI < 18.5 kg/m2) was 39% (37% in men and 40.3% in women). The prevalence of overweight and obesity (BMI ≥ 25.0 kg/m2) was found to be 7.1% among only women. The average daily energy intake was calculated to be 2,290 kcal per capita. It is worth noting that the food and nutrient consumption of the Oraon tribe was largely consistent with the recommended daily allowances/intakes (RDA/RDI). The consumption of root and tuber products was particularly high. The Oraon tribe was found to have a familiar intake of animal protein in the form of meat, including common periwinkles (Littorina littorea). The study also discovered a remarkable array of unique, region-specific festive foods. The consumption of nutrient-rich fermented rice beer was especially noteworthy.ConclusionThe present study provides insight into the traditional food practices of the Oraon tribe in West Bengal. It also highlights that their indigenous food consumption patterns have undergone significant changes as a result of admixture with other communities. To address these dietary issues, it is recommended that regional, need-based planning, and effective intervention programs be implemented. To ensure the proper maintenance of the Oraon tribe's traditional food practices, the cultivation of kitchen gardens and the domestication of wild, edible plants, such as seeds and tubers, may be helpful. Moreover, promoting the consumption of macronutrient-fortified handia, an indigenous beverage with high medicinal benefits, could be effective in combating hidden hunger among adults.

Seagrass is protected from ragworm pressure by a newly discovered grazer–ragworm interaction; implications for restoration

Abstract Coastal ecosystems are generally controlled by the combination of bottom‐up (resource‐driven) and top‐down (consumer‐driven) trophic, and non‐trophic interactions. Anthropogenic disruption of these interactions, for example, through eutrophication or overfishing, leads to loss of the foundation species composing these ecosystems. Within degraded ecosystems, new interactions may become dominant, hampering restoration of the foundation species. We demonstrate this concept in saltwater Lake Grevelingen, where seagrass restoration was seriously hampered by a newly discovered non‐trophic interaction between the seagrass Zostera marina and the ragworm Platynereis dumerilii. Platynereis constructs dwelling tubes between seagrass leaves by glueing and entangling them, leading to loss of biomass and increased epiphyte cover. To test the roles of epiphyte grazing (top‐down) and eutrophication (bottom‐up) on this new‐found interaction, we executed a field experiment introducing the snail Littorina littorea under natural nutrient concentrations and Platynereis densities and performed a full factorial mesocosm experiment applying Littorina, Platynereis and nutrient treatments. Our field results show that survival of reintroduced Zostera in Lake Grevelingen is seriously hampered by Platynereis, which can be suppressed by grazer addition. In our mesocosm experiment, we demonstrate that top‐down control by Littorina protects seagrass through two pathways: (1) mitigating bottom‐up regulated epiphyte growth by trophic top‐down forcing and (2) hampering the non‐trophic interaction between Zostera and Platynereis by grazing epiphytes and dwelling tubes. Synthesis and applications. With coastal ecosystems globally under pressure, our study emphasises the importance of understanding ecosystem‐specific trophic and non‐trophic key interactions when considering restoration. We show how negative interspecific interactions can become dominant in degraded systems with absent key facilitating interactions. Next, we show that these negative interactions (leaf glueing), inhibiting foundation species restoration, can be overruled by active inclusion of a key facilitating interactions (epiphyte grazing by mesograzers). Finally, we provide a three‐step co‐introduction approach for restoration management.

Dead molluscan shells from multiple trophic groups as archives of nitrogen isotopic evidence of wastewater gradients in estuaries

Increased coastal urbanization worldwide has resulted in increased nitrogen inputs to ecosystems, leading to eutrophication and other negative effects. We assessed δ15N in the dead-collected shells of three molluscan species in two estuaries in order to evaluate their ability to identify known gradients in wastewater nitrogen input, namely from private septic systems feeding directly into Waquoit Bay and from a groundwater plume reflecting wastewater injection at a municipal treatment plant in West Falmouth Harbor, Massachusetts, USA. Shells of a suspension-feeder (Geukensia demissa), a micro-algal grazer (Littorina littorea), and an omnivore (Nassarius obsoletus) were collected from lower intertidal sediments near the taxon's life habitat. We found that δ15N in dead-collected shells decreased significantly along the gradients of wastewater pollution in both estuaries, with similar results across all three trophic groups. These positive results demonstrate the potential of dead-shell assemblages for detecting spatial gradients of wastewater pollution.

AMINO ACIDS PROFILE AND BENEFICIAL METALS COMPOSITION OF SOME SELECTEDSPECIES OF SEAFOOD FROM SOMBREIRORIVER IN IDAMA, RIVERS STATE.

Seafood has been used widely as a vital source of animal protein and other beneficial metals.This study was designed to profile the amino acid and beneficial metal contents of Whelk (Buccinum undatum), Crab (Callinectes sapidus), Periwinkle (Littorina littorea), and Oyster (Crassostrea virginica) from Sombreiro River in Idama of Rivers State. Crude protein, amino acids, and metal contents of the seafood were determined using standard methods. Also, the leucine/isoleucine/valine, sodium/potassium, sodium/magnesium, and potassium/sodium ratios were determined. Data were statistically analysed with ANOVA. Results for the total proteins showed that Crab had the highest crude protein content of 25.17 ± 0.01 % while Whelk and Periwinkle had the lowest total crude contents respectively. All four shellfishes contained 9 essential amino acids required by most biological systems and 9 non-essential amino acids. Histidine, lysine, methionine, and phenylalanine were the most abundant nutritionally essential amino acids while glutamic and aspartic acids were the most abundant non-essential amino acids. It was revealed that Oyster had the highest percentage of total essential amino acids and Whelk had the highest percentage of total non-essential amino acids. The leucine/isoleucine/valine ratios showed that Periwinkle and Crab had a ratio of 1.0:1.0:1.0 each while Whelk and Oyster had 2.0:2.0:1.0 and 4.0:3.0:1.0. Also, potassium and magnesium were the most abundant metals. All the metals analysed and the mineral ratios calculated were below the internationally acceptable limits. These results, therefore, revealed that the seafood analysed was of high nutritive values which might be useful in clinical nutrition and counselling.

Symbiont-induced phenotypic variation in an ecosystem engineer mediates thermal stress for the associated community

Microbial symbionts have strong potential to mediate responses to climate change. Such modulation may be particularly important in the case of hosts that modify the physical habitat structure. By transforming the habitats, ecosystem engineers alter resource availability and modulate environmental conditions which, in turn, indirectly shape the community associated with that habitat. Endolithic cyanobacteria are known to reduce the body temperatures of infested mussels and here, we assessed whether the thermal benefits of endoliths on the intertidal reef-building mussel Mytilus galloprovincialis extends to the invertebrate community utilising mussel beds as habitat. Artificial reefs of biomimetic mussels either colonised or not colonised by microbial endoliths were used to test whether infauna species (the limpet Patella vulgata, the snail Littorina littorea and mussel recruits) in a mussel bed with symbionts experience lower body temperatures than those within a bed composed of mussels without symbionts. We found that infaunal individuals benefitted from being surrounded by mussels with symbionts, an effect that may be particularly critical during intense heat stress. Indirect effects of biotic interactions, complicate our understanding of community and ecosystem responses to climate change, especially in cases involving ecosystem engineers, and accounting for them will improve our predictions.

Rhamnolipids Mediate the Effects of a Gastropod Grazer in Regards to Carbon–Nitrogen Stoichiometry of Intertidal Microbial Biofilms

Microbial biofilms have co-evolved with grazing animals, such as gastropods, to develop mutually beneficial relationships. Although microbial biofilms demonstrate resilience and resistance to chemical exposure, pre-existing relationships can be negatively affected by chemical input. In this study, we determined how the grazer, Littorina littorea (common periwinkle sea snail), and a biological surfactant (rhamnolipid) interact on a phototrophic marine biofilm. Biofilms were cultured in 32 twenty-liter buckets at the Queen’s University Marine Laboratory in Portaferry, Northern Ireland on clay tiles that were either exposed to 150 ppm of a rhamnolipid solution or that had no chemical exposure. L. littorea were added into half of the buckets, and biofilms were developed over 14 days. Biofilms exposed to grazing alone demonstrated high tolerance to the disturbance, while those growing on rhamnolipid-exposed substrate demonstrated resistance but experienced slight declines in carbon and stoichiometric ratios. However, when exposed to both, biofilms had significant decreases in stoichiometry and declined in productivity and respiration. This is problematic, as continuing marine pollution increases the likelihood that biofilms will be exposed to combinations of stressors and disturbances. Loss of biofilm productivity within these areas could lead to the loss of an important food source and nutrient cycler within the marine ecosystem.