Trophic Changes Research Articles

Evidence of cultural eutrophication of the Gulf of Gdańsk based on diatom analysis

Abstract The objective of this study was to reconstruct the environmental changes in the Gulf of Gdańsk in the last 200 years. Four subbottom sediment cores were analyzed with respect to diatom flora and anthropogenic effects. The so-called “anthropogenic assemblage” – a result of cultural eutrophication – was observed in the surface sediments. Changes in the species composition may have been caused by the increased use of fertilizers, nitrogen loads and increasing organic matter concentration. Three phases (A, B and C) were distinguished based on the floristic spectrum, which clearly indicates trophic changes in the study area.

Recent trophic state changes of selected Florida lakes inferred from bulk sediment geochemical variables and biomarkers

Short sediment cores (80–100 cm) from three Florida (USA) lakes (Sheelar, Wauberg, and Apopka) that range in trophic status, were analyzed for total organic carbon (TOC), total nitrogen, stable isotopes of organic carbon (δ13CTOC) and biomarkers (n-alkanes and fatty acids), to identify the sources of organic matter in the lake deposits, and to link changes in primary productivity to anthropogenic activities during the last ~ 150 years. Relatively small (0.07 km2), ultra-oligotrophic Lake Sheelar is located in a state park, and sediment analyses indicate stable trophic status in the water body since at least the middle of the nineteenth century. Algal biomarkers are in low abundance throughout the core and terrestrial lipids and δ13CTOC values suggest that vascular plants were the primary source of TOC to the lake sediments during the period of record. In larger, eutrophic Lakes Wauberg (1.5 km2) and Apopka (125 km2), algal-derived biomarkers increase in recent sediments, whereas δ13CTOC values and concentrations of terrestrial biomarkers decrease toward the sediment surface. Increasing dominance through time of autochthonous carbon sources in the Lake Wauberg and Apopka sediment records coincides with specific anthropogenic activities in the respective watersheds. Submersed macrophytes in Lake Wauberg were replaced by algal communities in the mid-1980s, following expansion of residential development in the watershed. Biomarker data from the Lake Apopka core show there was an abrupt transition in the lake in the late 1940s, from domination by vascular plants to domination by algae, which has been documented by other paleolimnological studies that used alternative trophic state indicators. The trophic state shift in Lake Apopka corresponds to a period of increased nutrient input to the lake, associated with extensive farming along the north shore. Florida lakes have experienced different trophic state trajectories over the last ~ 150 years, driven by specific human activities in their respective watersheds.

Pathophysiology of Complex Regional Pain Syndrome and Treatment: Recent Advancements

Complex regional pain syndrome (CRPS) is a painful and debilitating disorder involving dysfunction in multiple body systems. This review seeks to evaluate recent data and present treatment options for the practical management of this condition. The mechanism by which CRPS develops is multifactorial, affecting both the peripheral and central nervous systems, and nerve changes can be seen at a histologic level. Treatment should be initiated as early as possible, as the chronic disease is less responsive to intervention. CRPS is a clinical diagnosis; treatment is symptomatic and aimed at addressing the sensory, vasomotor, sudomotor, and trophic changes which occur in the context of severe pain. Management may include therapy, oral or intravenous medication, procedures, or surgery.

Cross-sectional areas of rectus abdominis and psoas muscles reduces following surgery in rectal cancer patients.

To evaluate the trophic changes in rectus abdominis and psoas muscles in patients who underwent open or laparoscopic rectum resection for rectal cancer. We retrospectively analyzed preoperative staging computerized tomographies (CT) and postoperative first oncological follow-up CTs of the patients who underwent low anterior resection (LAR) for rectal cancer from 2010 through 2015. We measured cross-sectional area of left and right rectus abdominis muscles from two levels (above and below umbilicus) where they are widest and psoas muscle at mid-level of the fourth lumbar vertebral body in axial CT images and compared preoperative and postoperative measurements. We investigated the effects of age, sex, administration of preoperative chemoradiotherapy (CRT), type of surgery (open or laparoscopic), or construction of a diverting ileostomy on cross-sectional muscle area changes. After applying inclusion and exclusion criteria 60 patients found to be eligible for the study. Muscle areas of all measurement sites were reduced postoperatively compared to paired preoperative values. There was no significant effect of age, sex, administration of preoperative CRT, type of surgery (open or laparoscopic), or construction of a diverting ileostomy to muscle cross-sectional area reductions. Cross-sectional areas of the rectus abdominis and the psoas muscles of rectal cancer patients reduces following rectum resection which indicates atrophy of these muscles. Clinicians should be aware of this problem and focus on prevention of muscle atrophy during the treatment of rectal cancer patients.

Complex Regional Pain Syndrome: Current Diagnostic and Treatment Considerations.

Complex Regional Pain Syndrome is a severe complication of extremity fracture or other injury. Patients who develop this show marked hyperalgesia and allodynia, altered vasomotor, sudomotor and trophic changes. The condition affects women more than men and is most common in those between the ages of 50 and 70 years but can be seen in younger athletes. The diagnosis is made clinically, and treatment is directed at functional recovery using medications, occupational and physical therapy, and psychological interventions. Prognosis for complete recovery is variable and unpredictable.

Evaluation and Management of Chronic Venous Disease Using the Foundation of CEAP.

Venous disease is common. Depending on the population studied, the prevalence may be as high as 80%. Significant chronic venous disease with venous ulcers or trophic skin changes is reported to affect 1-10% of the population. A systematic assessment of the clinical findings associated with chronic venous disease will facilitate appropriate imaging. Based on imaging and assessment, patients with reflux or obstruction can be recommended proper medical and endovascular or surgical management. Many types of endovascular management are available to treat reflux and eliminate varicose veins and tributaries. More recently adopted non-thermal non-tumescent techniques have been shown to be comparable with more widely performed laser or radiofrequency ablation techniques. A thorough clinical assessment, appropriate duplex ultrasound imaging, and use of advanced imaging when needed will allow clinicians to optimize therapy for patients with chronic venous disease based on the etiology, anatomy involved, and the pathophysiology.

Trophic niche changes associated with habitat fragmentation in a Neotropical bat species

AbstractHabitat fragmentation could alter ecological traits including species trophic habits. Here, we used carbon and nitrogen stable isotope ratios to establish differences in isotopic niche width and food resource use between forest fragments and the continuous forest for the phyllostomid frugivorous bat Artibeus lituratus. Using mist nests, we captured bats from two forest fragments and two sites in continuous forest, and sampled from each individual captured three body tissues with contrasting turnover rates (skin, muscle, and liver). Samples were collected between February and March (austral summer) and between August and September (austral winter). In addition, in each sampling site and season we collected potential food resources (fruits and insects) consumed by our A. lituratus. Our findings indicate that A. lituratus had a predominantly omnivorous diet, with high consumption of insects during summer in forest fragments. The increasing consumption of insects in these fragments seems to have led to a wider isotopic niche, in relation to the continuous forest. Because A. lituratus is typically a seed disperser, changes in trophic habits in the forest fragments from frugivory to insectivory may diminish their role in forest regeneration.Abstract in Portuguese is available with online material.

Body burden of pesticides and shape asymmetry in carabid beetles in different agricultural practices in Mediterranean agroecosystems

Neonicotinoids have been the most commonly used insecticides worldwide in the last two decades, whereas application of Copper (Cu) has a much longer history, especially in Mediterranean agriculture, (e.g. vineyards). Lately, large numbers of studies have shown negative effects of neonicotinoids on non-target species (especially on bees but also on other insects, and indirectly on insectivorous species like birds) being thus recently banned by EU commission. On the other hand, intensification of production in favour of ecological pest management increases the use of copper in pest control schemes and its absorption in agroecosystems. In this study we aimed to quantify the relationships between pesticide concentrations, including those with copper compounds, in soil, carabids and its prey at four sampling sites, in vineyards and olive groves under integrated (IPM) and ecological pest managements (EPM), and in pristine habitats in Zadar County, in Mediterranean region of Croatia. Soil, carabids, earthworms, snails and woodlice were sampled using pitfall traps and by hand. LC-MS/MS and ICP-MS technique were utilised to quantify pesticides and Cu concentrations in the soil and in the animals representing different trophic guilds. In addition we analysed changes in body shape symmetry of Poecilus koyi, one of the most dominant predatory carabid species in the study sites, in order to evaluate the potential environmental stress between maned and pristine habitats that can affect carabids during their development. Geometric morphometrics (GMM) has been used to analyse pronotum and abdomen shape variations, and left/right asymmetries in up to100 individuals of P. koyi per study site. Some preliminary results showed that body burden with pesticides differ between prey and predator organisms, and body concentrations of certain pesticides in carabid beetles did not correlate with those in the soil. Distribution of pesticide along different trophic guilds and changes in body shape and fluctuating asymmetry in P. koyi populations will be presented and discussed in details.

Diatom-inferred ecological responses of an oceanic lake system to volcanism and anthropogenic perturbations since 1290 CE

The impacts of natural- and human-induced processes on lake ecosystems in remote oceanic islands remain to be fully elucidated. These lakes are excellent candidates to analyze the importance of anthropogenic vs. natural forces driving lacustrine long-term ecological evolution from previous pristine pre-colonized conditions. Disentangling the effects of both is particularly relevant in highly active volcanic areas, where catastrophic eruptions can act as an atypical natural driver altering the lake's long-term ecological trajectories. In this paper we study past ecological changes occurring in Lake Azul (São Miguel island), a crater lake from the remote Azorean archipelago, to address which were the main causes of its long-term trophic history. We analyzed diatom assemblages, sedimentology, and bulk organic matter of sediments deposited since ca. 1290 CE, when a huge local eruption occurred. This episode drove the evolution of Lake Azul through six distinct phases, commencing with a restart of ecological succession after tephra deposition disrupted biogeochemical cycling. The alteration was so profound that the lake underwent a state of oligotrophic conditions for approx. 650 yr. Nutrients were sourced by fish-induced internal recycling and the overflow of the near Lake Verde during this period, rather than by allochthonous nutrient inputs modulated by climate variability and/or vegetation cover changes in the watershed after the official Portuguese colonization. It was only after recent artificial fertilization when the system overcame the volcanic-induced long-term resilience. This over-fertilization and a reduction in water turnover exacerbated the recent symptoms of eutrophication after 1990 CE. Contrary to other studies, Lake Azul constitutes an uncommon case of long-term resilience to trophic change induced by a cataclysmic volcanic eruption. It brings new insights into the fate of lake ecosystems which might be affected by similar events in the future.

Space use patterns affect stable isotopes of polar bears (Ursus maritimus) in the Beaufort Sea

Space use patterns vary within a population and can influence diet composition of individuals. Within the Beaufort Sea, polar bears (Ursus maritimus) either use offshore areas and follow sea ice retreat (pelagic) or utilize nearshore areas (coastal), exposing individuals to different food sources. We examine the relationship between coastal and pelagic space use patterns and diet quantified by stable isotopes (δ15N and δ13C) of polar bears in the Beaufort Sea between 2007 and 2011. We examined spatial fidelity using home range overlap and assigned bears to one of two space use patterns (coastal or pelagic) based on proximity of home ranges to the coast. We estimated diet composition using inter- and intratissue variability in stable isotopes from hair and claws to examine seasonal shifts in diet. Sectioning of claws provided additional insights on diet, but guard hair sections did not. Polar bears showed spatial fidelity between years. Nitrogen stable isotopes were related to space use patterns. Coastal bears were 15N-depleted compared to pelagic bears due to coastal bears being enriched in 15N possibly from either scavenging on bowhead whale carcasses (Balaena mysticetus) killed during subsistence hunts or pelagic bears being nutritionally stressed. Although upper trophic level predators can provide insight into trophic dynamics and changes in ecosystem function, knowledge of space use patterns and foraging behavior is an important aspect of diet interpretation.

Carbon dioxide fixation coupled with ammonium uptake by immobilized Scenedesmus obliquus and its potential for protein production

In this study, immobilized Scenedesmus obliquus (S. obliquus) was proposed to simultaneously alleviate the carbon dioxide (CO2) and ammonium (NH4+-N). Two trophic modes of autotrophy and mixotrophy were conducted by batch experiments with a period of 5 days. The results shown that NH4+-N could be removed more efficiently if algal cells were immobilized, and the trophic mode change had no significant effect on immobilized S. obliquus to NH4+-N removal under 5% CO2 sparging. Specifically, immobilized S. obliquus could remove NH4+-N completely at initial concentrations of 30 and 50 mg/L and reached about 80% removal rate of NH4+-N at the concentration of 70 mg/L under both trophic modes. The protein synthesis was its main removal mechanism and the dominant amino acid components including glutamic acid (Glu), cystine (Cys), arginine (Arg), methionine (Met) and lysine (Lys) were sensitive to NH4+-N assimilation.

Fingertip amputations treated with occlusive dressings

The aim of this study was to analyze a series of patients who suffered a distal finger amputation and who were treated with occlusive dressings. A retrospective study was done of 19 patients from a single hospital. At the review, an independent examiner evaluated the time required for wound healing, the number of occlusive dressings used, fingertip trophic skin changes, epicritic sensitivity using the Weber two-point discrimination (2PD) test, sensitivity based on the monofilament test, complications, the presence of dysesthesia or cold intolerance, and the QuickDASH score. The mean follow-up was 12.6 months (6–25). A mean of 3.2 occlusive dressings (3–5) were used per patient, and the mean healing time was 4.3 weeks (4–5). The skin texture, fingertips and nail bed were good or excellent in 18 cases. The 2PD test was good or normal in 16 cases. Eighteen patients were satisfied or very satisfied with the outcome. The mean QuickDASH score was 5.53 (0–20.45). In the literature, the recovery of tactile sensation is good after use of occlusive dressings (2PD of 2.5 to 4.0mm). The mean sensitivity reported in various studies is better than that observed after use of a skin flap. While the sample size in our study was small, the functional outcome and appearance were good. Thus we prefer using occlusive dressings in Zone 1 and 2 fingertip amputations, and flaps in zones 3 and 4 to ensure better fingertip viability and sensation.

Trophic niche changes during settlement in the Argentine hake Merluccius hubbsi reveal the importance of pelagic food post metamorphosis

Trophic niche changes during settlement in the Argentine hake Merluccius hubbsi reveal the importance of pelagic food post metamorphosis

Long-term results of complex therapy in patients with nonreconstructible chronic lower limb ischemia

The aim — to improve the results of surgical treatment of patients with chronic critical lower limb ischemia by developing methods of autologous transplantation of multipotent stem mesenchymal stromal cells, administration of endothelial cells growth factors and therapeutic and diagnostic measures to preserve the lower limb or reduce the level of its amputation, reduce ischemia and the frequency of disability of such patients, improve their quality of life.Materials and methods. The study included 110 patients with a clinical picture of pain at rest, ischemic edema, and trophic changes (IIIA, IIIB, and IV stage of lower limb ischemia according to the classification of the European Association of Angiologists and Vascular Surgeons) caused by nonreconstructible occlusive and obliterating diseases of lower limb arteries. The patients were divided into three groups according to the method of treatment: in the 1st group (n = 48), revascularization osteotrepanation was performed as an operation of indirect revascularization, in the 2nd group (n = 21) a drug of endothelial cells growth factor was administered to stimulate their own angiogenesis, in the 3rd group (n = 41) subcutaneous fat was collected, autologous mesenchymal cells were cultivated and transplanted according to the developed technique. The control group of patients (n = 50) was selected retrospectively according to the case histories in accordance with the criteria of involvement and the results of treatment which could be followed up in a 3‑year observation period.Results and discussion. The safety of the lower limb in the 3rd group was statistically more significant than in the 1st and 2nd groups and remained at the level of 82 % after three years of observation. The smallest number of large amputations was in the 3rd group (2.3 % — above knee‑joint and 7.3 % — below, knee‑joint whereas in the control group the number was 18 % and 24 %, respectively).Conclusions. The level of high amputations directly affects the life expectancy of patients. Only treatment in the 3rd group reduced the risk of large amputation compared with the control group (odds ratio 2.752 (95 % confidence interval — 1.12 — 6.733)). Only treatment in the 3rd group reduced the risk of amputation compared with other types of treatment (odds ratio 0.358 (95 % confidence interval 1.111 — 1.158).

Uptake and trophic changes in polybrominated diphenyl ethers in the benthic marine food chain in southwestern British Columbia, Canada

We examined the physical and geochemical effects of sediment on the uptake of polybrominated diphenyl ethers (PBDEs) into marine sediment feeders and their transfer to higher trophic fauna. Sediment PBDEs increased with % total organic carbon (%TOC), organic carbon (OC) flux and grain size (%fines). Tissue PBDE variance was best explained ( R2 = 0.70) by sediment acid volatile sulfides (AVS), PBDEs, and organic lability and input, with the highest values near wastewater outfalls. Dry weight tissue/sediment PBDEs declined with increasing sediment PBDEs, resulting in tissue dilution (ratio <1) at >10 000 pg/g in harbours. Ratios also decreased with increasing %fines, resulting in regional differences. These patterns imply that high levels of fines and high sediment concentrations make PBDEs less bioavailable. Dry weight PBDEs increased >100× between background deposit feeders and predators (polychaetes, crabs, bottom fish, seal), but lipid normalized PBDEs barely increased (<1.3%), suggesting remarkably high uptake in low-lipid sediment feeders, and that PBDEs don’t accumulate at higher trophic levels, but lipid content does. Filter feeders had lower lipid-normalized PBDEs than deposit feeders, highlighting the importance of food resources in higher trophic fauna for bioaccumulation. The most profound congener change occurred with sediment uptake, with nona/deca-BDEs declining and tetra-hexa-BDEs increasing. Harbour sediment feeders had more deca-BDEs than other samples, suggesting PBDEs mostly pass unmodifed through them. Deca-BDEs persist patchily in all tissues, reflecting variable dependence on sediment/pelagic food.

Long-Term Changes in the Zooplankton Community of Lake Maggiore in Response to Multiple Stressors: A Functional Principal Components Analysis

We describe the long-term (1981–2008) dynamics of several physico-chemical and biological variables and how their changes may have influenced zooplankton structure in Lake Maggiore (Italy). Data was available for the 1981–1992 and 1995–2008 periods. Standardized time-series for temperature and total phosphorus (TP), chlorophyll-a, phytoplankton density (cel m−3), and cell size (µm3), as well as zooplankton structure (Copepoda, Cladocera, and Rotifera density, ind m−3) were smoothed using penalized B-splines and analyzed using Functional Principal Components (FPCs) to assess their dominant modes of variation. The first four FPCs explained 55% of 1981–1992 and 65% of 1995–2008 overall variation. Results showed that temperature fluctuated during the study period, particularly during 1988–1992 with a general tendency to increase. TP showed a declining trend with some reversions in the pattern observed in the years 1992, 1999, and 2000. Phytoplankton estimators and chlorophyll-a concentration showed a variable trend along the study period. Zooplankton groups also had a variable trend along the study period with a general increase in density of large carnivorous (mainly Bythotrephes longimanus) and a decrease of large herbivorous (mainly Daphnia), and a similar increase in the ratio of raptorial to microphagous rotifers. Our results suggest that the lake experienced a strong trophic change associated with oligotrophication, followed by pronounced climate-induced changes during the latter period. TP concentration was strongly associated with changes in abundance of some zooplankton taxa.

Long-term changes of the trophic status in transitional ecosystems of the northern Adriatic Sea, key parameters and future expectations: The lagoon of Venice as a study case

The determination of the trophic status of transitional ecosystems from the physico-chemical and biological point of view is one of the requirements of the European Water Framework Directive (WFD 2000/60/EC). In Italy, its determination is implemented by the Regional Agencies for Environmental Protection (ARPAs) that have activated multi-annual monitoring programs. However, as the availability of funds is increasingly scarce, the number of environmental parameters to detect environmental changes should be conveniently managed. The high number of environmental parameters, nutrient and macrophyte datasets available for the LTER-Italia site “Venice lagoon” can be an useful tool to analyze the trophic changes over recent years and to foresee environmental evolutions. Nutrient data on a spatial basis have been available since 1948, whereas macroalgal maps date back to 1980. The aim of this paper is to highlight the changes of the trophic status of the lagoon since the middle of the 20th century by considering the concentrations of nutrients in the surface sediments and in the water column, the variation of some physico-chemical parameters and the biomass of macroalgae and also to foresee the way it will possibly evolve. In fact, after many anthropogenic impacts that in the second half of the 20th century affected the lagoon, starting from the year 2010, the ecological status is progressively improving. Nutrients show a significant reduction both in the water column and in surface sediments, and the macrophytes are represented by species of higher ecological value while the opportunistic species such as the Ulvaceae are in strong regression.

Mycorrhizal symbioses and the evolution of trophic modes in plants

Abstract Since the early colonization of land, plants depend, to various extents, on mycorrhizal fungi to meet their nutrient demands. In most mycorrhizal symbioses, plants provide sugars derived from photosynthesis to the fungi, whereas the fungi provide essential minerals to the plant. However, in some plants, the flow of carbon has reversed and the fungi provide carbon to the plants. These plants are called mycoheterotrophs. However, it remains unclear how and under which circumstances trophic modes change and whether transitions in trophic modes are associated with changes in mycorrhizal communities. Here, we review the available literature on mycorrhizal associations and trophic modes in plants. We first outline how trophic modes can be determined and how they differ across plants. We then investigate the evolutionary context under which mycoheterotrophy originated. We also examine the mycorrhizal communities associating with autotrophic, partially mycoheterotrophic and fully mycoheterotrophic plants within different plant families and investigate whether commonalities can be observed. Our overview shows that mycoheterotrophy has originated more than 40 times through evolutionary time and can be found in a wide range of plant groups, including liverworts, lycophytes, ferns, monocots and dicots. Partial mycoheterotrophy appears to be much more common than previously anticipated and represents an almost continuous gradient between autotrophy and full mycoheterotrophy. Comparison of the mycorrhizal communities associating with autotrophic, partial and full mycoheterotrophic plants indicates that, although they share some commonalities, shifts from autotrophy to full mycoheterotrophy are accompanied by either losses or shifts in mycorrhizal partners, suggesting that full or partial loss of photosynthesis selects for different mycorrhizal communities. Synthesis. Partial mycoheterotrophy appears to be much more common than previously thought and represents an almost continuous gradient from autotrophy to full mycoheterotrophy. Evolution to full mycoheterotrophy is challenging as it requires specific adaptations and often a switch to other mycorrhizal partners. More detailed analyses of the functionality of different mycorrhizal systems co‐occurring in the roots of a single plant and the costs of mycorrhizal switching are needed to understand the precise mechanisms leading to full mycoheterotrophy.

Delayed Treatment of Capsaicin Produces Partial Motor Recovery by Enhancing Dopamine Function in MPP+-lesioned Rats via Ciliary Neurotrophic Factor.

Transient receptor potential vanilloid subtype 1 (TRPV1) on astrocytes prevents ongoing degeneration of nigrostriatal dopamine (DA) neurons in MPP+-lesioned rats via ciliary neurotrophic factor (CNTF). The present study determined whether such a beneficial effect of astrocytic TRPV1 could be achieved after completion of injury of DA neurons, rather than ongoing injury, which seems more relevant to therapeutics. To test this, the MPP+-lesioned rat model utilized here exhibited approximately 70~80% degeneration of nigrostriatal DA neurons that was completed at 2 weeks post medial forebrain bundle injection of MPP+. TRPV1 agonist, capsaicin (CAP), was intraperitoneally administered. CNTF receptor alpha neutralizing antibody (CNTFRαNAb) was nigral injected to evaluate the role of CNTF endogenously produced by astrocyte through TRPV1 activation on DA neurons. Delayed treatment of CAP produced a significant reduction in amphetamine-induced rotational asymmetry. Accompanying this behavioral recovery, CAP treatment increased CNTF levels and tyrosine hydroxylase (TH) activity in the substantia nigra pars compacta (SNpc), and levels of DA and its metabolites in the striatum compared to controls. Interestingly, behavioral recovery and increases in biochemical indices were not reflected in trophic changes of the DA system. Instead, behavioral recovery was temporal and dependent on the continuous presence of CAP treatment. The results suggest that delayed treatment of CAP increases nigral TH enzyme activity and striatal levels of DA and its metabolites by CNTF endogenously derived from CAP-activated astrocytes through TRPV1, leading to functional recovery. Consequently, these findings may be useful in the treatment of DA imbalances associated with Parkinson's disease.

Pacific walrus diet across 4000 years of changing sea ice conditions

AbstractDeclining sea ice is expected to change the Arctic's physical and biological systems in ways that are difficult to predict. This study used stable isotope compositions (δ13C and δ15N) of archaeological, historic, and modern Pacific walrus (Odobenus rosmarus divergens) bone collagen to investigate the impacts of changing sea ice conditions on walrus diet during the last ~4000 yr. An index of past sea ice conditions was generated using dinocyst-based reconstructions from three locations in the northeastern Chukchi Sea. Archaeological walrus samples were assigned to intervals of high and low sea ice, and δ13C and δ15N were compared across ice states. Mean δ13C and δ15N values were similar for archaeological walruses from intervals of high and low sea ice; however, variability among walruses was greater during low-ice intervals, possibly indicating decreased availability of preferred prey. Overall, sea ice conditions were not a primary driver of changes in walrus diet. The diet of modern walruses was not consistent with archaeological low sea ice intervals. Rather, the low average trophic position of modern walruses (primarily driven by males), with little variability among individuals, suggests that trophic changes to this Arctic ecosystem are still underway or are unprecedented in the last ~4000 yr.