Download or read book The Interconnectedness of Diet Physiology and Physical Condition in Beluga Whales as a Sentinel Species for Environmental Change in the Beaufort Sea Ecosystem written by Emily Sarah Choy and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Beaufort Sea Beluga Whales written by Lisa Lucia Loseto and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mercury (Hg) levels in the Beaufort Sea beluga (Delphinapterus leucas) population have been increasing since the 1990's. Ultimately, it is the Hg content of prey that determines beluga Hg levels. However, the Beaufort Sea beluga diet is not understood, and little is known about the food webs and Hg sources in their summer habitat. Using satellite telemetry data, the Beaufort Sea Beluga were found to segregate into habitat use groups, by length, sex and reproductive status. Segregation of habitat use lead to the hypothesis that beluga may feed differently, explaining Hg dietary sources. Mercury levels were measured in three food webs in the western Canadian Arctic to assess their dietary Hg contribution. Results revealed that potential beluga prey had variable Hg concentrations. With the use of the diet biomarkers stable isotopes and fatty acids in both prey items and beluga, the beluga diet was evaluated by incorporating beluga biological variables such as age, length, sex and harvest location. Here, we show the factors driving beluga diet variability lead to differences in dietary Hg uptake. Diet variability within the Beaufort Sea beluga was evident, whereby larger beluga appeared to feed predominantly on offshore arctic cod (Boreogadus Saida), and medium and smaller sized beluga incorporated more near-shore fish collected from the Mackenzie shelf. The variation in beluga diet was supported by the differences in Hg concentrations and 815N values in both prey and beluga. For the first time, we demonstrate that food web Hg biomagnification processes drive beluga muscle Hg levels, rather than Hg bioaccumulation over time. This conclusion revealed that dietary Hg levels varied with habitat use, where the shelf was low source of Hg and the offshore was a high source. Therefor, incorporating beluga habitat use along with food web complexity was important in determining the factors driving beluga Hg levels. These observations lend support to the possibility that the high levels of Hg leaving the Mackenzie River only become bioavailability for food web uptake once entering offshore habitats"--Leaves [i]-ii

Download or read book Beaufort Sea Beluga Whales written by Lisa Lucia Loseto and published by . This book was released on 2007 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mercury (Hg) levels in the Beaufort Sea beluga (Delphinapterus leucas) population have been increasing since the 1990's. Ultimately, it is the Hg content of prey that determines beluga Hg levels. However, the Beaufort Sea beluga diet is not understood, and little is known about the food webs and Hg sources in their summer habitat. Using satellite telemetry data, the Beaufort Sea Beluga were found to segregate into habitat use groups, by length, sex and reproductive status. Segregation of habitat use lead to the hypothesis that beluga may feed differently, explaining Hg dietary sources. Mercury levels were measured in three food webs in the western Canadian Arctic to assess their dietary Hg contribution. Results revealed that potential beluga prey had variable Hg concentrations. With the use of the diet biomarkers stable isotopes and fatty acids in both prey items and beluga, the beluga diet was evaluated by incorporating beluga biological variables such as age, length, sex and harvest location. Here, we show the factors driving beluga diet variability lead to differences in dietary Hg uptake. Diet variability within the Beaufort Sea beluga was evident, whereby larger beluga appeared to feed predominantly on offshore arctic cod (Boreogadus Saida), and medium and smaller sized beluga incorporated more near-shore fish collected from the Mackenzie shelf. The variation in beluga diet was supported by the differences in Hg concentrations and 815N values in both prey and beluga. For the first time, we demonstrate that food web Hg biomagnification processes drive beluga muscle Hg levels, rather than Hg bioaccumulation over time. This conclusion revealed that dietary Hg levels varied with habitat use, where the shelf was low source of Hg and the offshore was a high source. Therefor, incorporating beluga habitat use along with food web complexity was important in determining the factors driving beluga Hg levels. These observations lend support to the possibility that the high levels of Hg leaving the Mackenzie River only become bioavailability for food web uptake once entering offshore habitats"--Leaves [i]-ii.

Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.

Download or read book Proceedings of a Workshop on Beaufort Sea Beluga written by Wayne S. Duval and published by . This book was released on 1993 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Workshop held to examine the status of the stock of beluga whales that summer in the Beaufort Sea; to identify the best methods for the continued monitoring of the stock in response to human activities and environmental changes; and to define research priorities for the future. This document describes the structure of the workshop and its goals; gives background information on models; summarizes the subgroup discussions on stock status and population estimates and on continuing assessment; and discusses funding priorities, including the need for satellite tagging and aerial surveys.

Download or read book Beluga Summit written by Shannon MacPhee and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "For over 30 years these studies have successfully blended traditional knowledge and western science and increased our understanding of the numbers, life history and health of beuga whales in the Beaufort Sea. The program has yielded an Inuvialuit Beluga Management Plan, hundreds of scientific papers, worldwide respect, and successfully achieved the intent of the third key principle of the Inuvialuit Final Agreement "To protect and preserve Arctic wildlife, environment, and biological productivity". ... I am confident that this spirit of cooperation will continue through our Beluga summit and create guidance for the coming years as we strive to improve our knowledge and understanding of beluga in the ISR. ... Introductory remarks: The Beluga Summit is bringing together researchers, harvesters, Elders, youth and resource managers for the sharing of knowledge about beluga whales. During this three-day gathering, researchers and community members will have the chance to present their knowledge about belugas. Together, we will identify common concerns and knowledge gaps in beluga research and monitoring to help direct future beluga whale research in the ISR. The Steering Committee developed the format and content of the Beluga Summit in collaboration with community delegates, HTCS and researchers to ensure that the meeting would meet the following goals: -Share knowledge on beluga whales; -Summarize our current state of knowledge; -Develop a plan for research and management of beluga whales for the next 5 to 10 years; -Support the preparation of a publication that will assist management of beluga in the ISR. Community representatives will be full participants at the meeting and are there to learn from others as well as share their knowledge and perspectives. The three broad areas of sharing from a community perspective include cultural practices (e.g. sharing, hunting/food preparations), knowledge about beluga whales and the ecosystem (e.g. noting changes in belugas and the ecosystem) and perspectives on future research and monitoring (e.g. what is needed or what should be adjusted to increase our knowledge on beluga whales). Scientists and research advisors from the Department of Fisheries and Oceans (DFO), Health Canada, Northern Contaminants Program, Inuit Tapiriit Kanatami, Canadian universities and research institutes are travelling to Inuvik to share knowledge with community members and resource managers. Researchers studying beluga ecology and physiology, human health, contaminants, disease and Traditional Ecological Knowledge will present their research, learn about Inuvialuit knowledge and perspectives, and contribute to discussions about future research and monitoring. Managers and staff from the co-management boards, DFO, Inuvialuit Regional Corporation and the Alaska Beluga Whale Committee will contribute a regional, national and international perspective to beluga management concerns. They will also have the opportunity to hear directly from community delegates and scientists studying and living in the ISR. The Summit provides an important opportunity for beluga knowledge-holders to come together, bring their knowledge together to bring us to our current understanding of belugas in the context of environmental change. We hope this event fosters communication and collaboration among the many knowledge holders engaged in beluga whale harvesting, monitoring and research on beluga whales. We are excited for your participation in the development of a future plan for beluga in the ISR!"--ASTIS database.

Download or read book Beluga Whale Distribution Migration and Behavior in a Changing Pacific Arctic written by Donna D. W. Hauser and published by . This book was released on 2016 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sea ice is disappearing at unprecedented rates in the Pacific Arctic with potential impacts to ice-associated marine predators that migrate to this seasonally accessible and productive ecosystem. In this dissertation I used satellite telemetry data spanning 1993-2012 collected from two migratory populations of beluga whales (Delphinapterus leucas) in the Pacific Arctic (i.e., Eastern Chukchi Sea and Eastern Beaufort Sea populations) to investigate how loss of sea ice and changes in other environmental factors affect distribution, movement, and behavior. I quantified fidelity to summer areas, sexual segregation, and migration timing as well as variations in diving behavior among regions. These analyses illustrate that population-scale patterns of philopatry, migration, and foraging are mediated by the combined effects of seasonal sea ice and oceanographic fluctuations, prey distribution, and social interactions. I also addressed the question of whether belugas would adjust their distribution, migration, and behavior to shifting sea ice conditions and to what extent matrilineally-learned behavior might supersede environmental forcing through the development of resource selection functions. Results indicate that sea ice is a contributing factor but not sole determinant of beluga habitat preferences. One population (Eastern Chukchi Sea) exhibits delayed fall migration in response to later sea ice freeze-up. Changing environmental conditions also seem to favor deeper, longer dives for this population. There were few overall differences in preferred habitat selection during 1990-2014, and summer distribution appears to be governed by philopatry rather than ice conditions. These results correspond to a conclusion that Eastern Chukchi Sea belugas are responding to a changing Pacific Arctic environment through behavioral plasticity in migration timing and foraging behavior. In contrast, there were few examples where migration timing or sea ice associations of Eastern Beaufort Sea belugas changed between the 1990s and 2000s. Taken as a whole, these results suggest population-specific responses by belugas in the face of fluctuating sea ice conditions. Across the circumpolar Arctic, some beluga populations may be more likely than others to adapt and persist in a changing climate.

Download or read book Study of Summer and Fall Movements and Dive Behaviour of Beaufort Sea Belugas Using Satellite Telemetry 1992 1995 written by P. R. Richard and published by Environmental Studies Research Funds. This book was released on 1997 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Conservation Physiology of Arctic Cetaceans written by Justine Hudson and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conservation physiology is a field of study that focuses on physiological changes in response to human activity and environmental change, including elevations in stress hormones, changes in metabolism, and declines in reproductive hormones, body condition and immune function. Physiological changes such as these can indicate environmental pressures and be used to monitor the health of wildlife populations. In this study, I analyzed endocrine data of two Arctic cetaceans, the Western Hudson Bay beluga population and the Eastern Canada-West Greenland bowhead whale population to better understand how they may respond to climate change. In Chapter 2, I demonstrated, for the first time, that it was possible to collect blow samples from free-swimming beluga whales and that cortisol and urea concentrations could be reliably measured in beluga blow samples. Urea was found to be an unsuitable dilution marker to normalize blow samples. Absolute cortisol concentrations were influenced by sample device, quantity rating, and age class, while urea concentrations were only influenced by sample device. In Chapter 3, I determined baseline triiodothyronine (T3) and corticosterone concentrations measured from baleen plates collected from bowhead whales and conservatively concluded that bowhead whales foraged year-round, based on a lack of observed seasonal variation in T3 and a lack of correlation between T3 and stable isotope values. Interestingly, we found a strong positive correlation between T3 and corticosterone in each whale, which requires further investigation. This research provides important baseline information about Arctic marine mammal endocrinology and establishes key recommendations for carrying out physiological studies.

Download or read book Passive Acoustic Monitoring to Identify Drivers of Beluga Whale Habitat Use in the Mackenzie Estuary written by Kevin Scharffenberg and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding drivers of habitat use of mobile species is critical for understanding the impacts of climate change and formulating management plans. Eastern Beaufort Sea (EBS) beluga whales (Delphinapterus leucas), an important subsistence food source for Inuvialuit, are known to form large aggregations in the Mackenzie Estuary each summer; however, environmental drivers of this habitat use are not understood. Passive acoustic monitoring was used to record beluga presence during this aggregation at key locations in the Mackenzie Estuary, while simultaneously recording environmental and oceanographic data. Belugas moved further into the estuary during cold oceanic influxes and did not use locations which typically see high use during high-speed winds. In an extreme case, a large storm prevented belugas from using the area for five days and negatively affected the subsistence beluga hunt. This information can inform decisions by northern communities and policy makers, aiding in management of the EBS beluga population.

Download or read book Beluga Whale Habitat Selection and Distribution in the Mackenzie Estuary and the Tarium Niryutait Marine Protected Area written by Aurelie Noel and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Eastern Beaufort Sea (EBS) beluga population migrates to the Mackenzie Estuary and to the Tarium Niryutait Marine Protected Area every summer and the reasons behind this selection are not fully understood. Once in the Estuary, beluga whales (Delphinapterus leucas) are harvested by Inuvialuit communities of the Inuvialuit Settlement Region for whom they represent an essential country food, contributing to their well-being. In the last decade, community members voiced their concerns and identified research priorities pertaining to belugas resources, baselines and habitats. To enhance our understanding of EBS beluga whale habitat and further anticipate effects of a changing climate, it was crucial to understand why belugas select these habitats. We created a habitat model based on aerial surveys observations from the late summer 2019 paired with remote sensing imagery to establish a baseline of environmental and spatial conditions selected by belugas. Then we assessed the baseline against historical data. We finally evaluated the habitat model with concurrent tagged observations to integrate the inferences made at a larger spatio-temporal scale. High turbidity and warm water temperatures were the two most important factors explaining beluga presence and were associated with the inshore waters of the Mackenzie River channels and along unprotected coastlines. Comparisons with past observations suggested that the observed beluga distribution had shifted from the baseline and was probably the results of the influence of changing environmental conditions on beluga response, either on a temporary (i.e., acclimatisation) or permanent basis (i.e., adaptation). The evaluation of the habitat model showed mixed results. The inferences of selection, created in combining quality of environmental conditions and belugas mechanisms of selection, explained the intertwined patterns of beluga habitat distribution. Those findings enhanced our understanding of EBS beluga ecology and highlighted the complexity in defining and predicting beluga habitat distribution. This complexity, by preventing an accurate assessment of the changing beluga habitat distribution, represents new challenges for harvesters that who may have to switch the timing and location of their harvest in response.

Download or read book Current and Novel Tools in the Health Assessment of Large Whales written by Kelly Ann Cates and published by . This book was released on 2021 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alaskan marine ecosystems are undergoing unprecedented change and species are facing increasingly variable and potentially inhospitable habitats. As top predators, marine mammals serve an important role as sentinels of ecosystem health. With their high site fidelity, abundant numbers, coastal presence and role as a top predator, humpback whales (Megaptera novaeangliae) provide a meaningful view into current ecosystem conditions and processes. In order to tap into their usefulness as bioindicators the basic physiology of humpback whales needs to be understood. Physiological indices can provide valuable information about fecundity, survival, health and population age structuring which is fundamental to cetacean research and population management. However, such information is often difficult to obtain from wild cetaceans as they surface infrequently and often live in remote or logistically challenging locations. As such, few methods currently exist for the assessment of physiological parameters of free ranging, large cetaceans. This dissertation paired existing methods of physiological examination with novel approaches in order to better understand the basic physiology and overall health of humpback whales. Specifically, six enzyme immunoassays were validated for use in humpback whales for progesterone, testosterone, cortisol, corticosterone, aldosterone and DHEA-S, an algorithm termed “Morphometer” was developed to automate the process of measuring and analyzing morphometric measurements, and hormones and body condition metrics were paired to determine whether pregnancy status can be detected from aerial photographs. This project seeks to lay the groundwork for long term monitoring of humpback whales that can provide critical information to managers. By using baseline physiological indices and tools to rapidly analyze these metrics that I developed here, managers and researchers will be able to analyze current and future samples within a longitudinal context and make management decisions based on more accurate biological information for these populations.

Download or read book The Arctic in the Anthropocene written by National Research Council and published by National Academies Press. This book was released on 2014-07-31 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Once ice-bound, difficult to access, and largely ignored by the rest of the world, the Arctic is now front and center in the midst of many important questions facing the world today. Our daily weather, what we eat, and coastal flooding are all interconnected with the future of the Arctic. The year 2012 was an astounding year for Arctic change. The summer sea ice volume smashed previous records, losing approximately 75 percent of its value since 1980 and half of its areal coverage. Multiple records were also broken when 97 percent of Greenland's surface experienced melt conditions in 2012, the largest melt extent in the satellite era. Receding ice caps in Arctic Canada are now exposing land surfaces that have been continuously ice covered for more than 40,000 years. What happens in the Arctic has far-reaching implications around the world. Loss of snow and ice exacerbates climate change and is the largest contributor to expected global sea level rise during the next century. Ten percent of the world's fish catches comes from Arctic and sub-Arctic waters. The U.S. Geological Survey estimated that up to 13 percent of the world's remaining oil reserves are in the Arctic. The geologic history of the Arctic may hold vital clues about massive volcanic eruptions and the consequent release of massive amount of coal fly ash that is thought to have caused mass extinctions in the distant past. How will these changes affect the rest of Earth? What research should we invest in to best understand this previously hidden land, manage impacts of change on Arctic communities, and cooperate with researchers from other nations? The Arctic in the Anthropocene reviews research questions previously identified by Arctic researchers, and then highlights the new questions that have emerged in the wake of and expectation of further rapid Arctic change, as well as new capabilities to address them. This report is meant to guide future directions in U.S. Arctic research so that research is targeted on critical scientific and societal questions and conducted as effectively as possible. The Arctic in the Anthropocene identifies both a disciplinary and a cross-cutting research strategy for the next 10 to 20 years, and evaluates infrastructure needs and collaboration opportunities. The climate, biology, and society in the Arctic are changing in rapid, complex, and interactive ways. Understanding the Arctic system has never been more critical; thus, Arctic research has never been more important. This report will be a resource for institutions, funders, policy makers, and students. Written in an engaging style, The Arctic in the Anthropocene paints a picture of one of the last unknown places on this planet, and communicates the excitement and importance of the discoveries and challenges that lie ahead.

Download or read book The Good the Bad and the Ugly written by Jean-Pierre Desforges and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Many of the factors that shape contaminant accumulation profiles in marine mammals also strongly influence fat soluble vitamin accumulation. Vitamin A and E are essential fat soluble nutrients for numerous biological processes, including reproduction, growth, endocrine and immune function. Contaminants, such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), can alter vitamin dynamics; as such these vitamins have been proposed as sensitive biomarkers of contaminant exposure in wildlife. In light of these considerations, the present thesis was aimed at better understanding the factors that influence the accumulation of lipophilic contaminants and vitamins in western Arctic beluga whales, and to determine if there was an interaction between the two. Maternal offloading to neonates during gestation reduced overall contaminant (PCBs and PBDEs) and vitamin (A and E) concentrations in reproductively active female whales. The PCB and PBDE congener pattern in mothers changed during gestation as a result of preferential transfer of light-low Log KOW congeners to the fetus. Overall, female beluga whales transferred approximately 11% of their PCB and PBDE blubber burden to their fetus. In terms of vitamins transfer, lower concentrations of tocopherols, retinol and retinyl esters were found in reproductively active females relative to males and reproductively inactive females. Metabolism was also found to be an important factor for contaminant and vitamin accumulation in beluga tissues. In a principal components analysis, PCBs clustered into metabolically-derived structure-activity groups, which separated along the first principal component according to its metabolic potential (metabolizable vs. recalcitrant). Contaminant-related up-regulation of metabolizing enzymes, including cytochrome P450, likely explained changes in the concentration and pattern of PCB and PBDE congeners, as well as hepatic, plasma, and blubber vitamin A and E. Since vitamins and lipophilic contaminants accumulated in beluga whales in the same way in relation to most biological processes, including sex, reproduction, size, condition, and feeding ecology, it was important to control and reduce the number of these confounding factors before claiming any tissue vitamin change was indeed the result of chemical exposure. In doing so, it was found that vitamin A and E homeostasis was influenced by PCBs in beluga whales, resulting in reduced hepatic storage and increased plasma and blubber concentrations. Overall, these results suggest that liver, plasma, and inner blubber vitamin A and E concentrations can be sensitive biomarkers of contaminant exposure only if major confounding effects are taken into consideration. The implications of altered vitamin dynamics on the health of beluga whales is unknown at this time; however, as Arctic marine mammals face continued stress related to climate change, increased human disturbance and emergence of infectious diseases, this study can serve as essential baseline data that can be used to monitor the health status of western Arctic beluga whales.

Download or read book Seasonal Movement and Habitat Use of Beluga Whales in the Canadian Beaufort Sea written by Claire Hornby (Alexandra) and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Environmental and Biological Factors Affecting Beluga Whale Delphinapterus Leucas Movement and Distribution in Hudson Bay written by Kristin Westdal and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beluga whales (Delphinapterus leucas) are an Arctic cetacean with circumpolar distribution. They are known to have distinct, lengthy and consistent migration paths to and from summer and wintering grounds. The Western Hudson Bay beluga population, the largest summering aggregation in the world, inhabits three main estuaries in the summer season. Little protection is afforded to them here, and little is known of the specific details of their summer distribution and factors affecting that distribution. Using a combination of satellite telemetry, aerial photos, satellite data, and visual observations and historical reports, investigations into factors affecting beluga distribution in Western Hudson Bay were conducted. An examination into beluga age class distribution near the Churchill and Seal River estuaries, using aerial survey imagery, suggested that belugas may not be segregating by age in summer, however the Seal River estuary may be more important from a calf-rearing perspective. Belugas use a greater home range than we would expect, based on historical range data, in the face of predation by their main predator, the killer whale (Orcinus orca). Killer whales are sighted more frequently in Hudson Bay than historically, and results presented here show that ice entrapments, occurring with higher frequency in the future, may impact distribution of beluga as killer whales expand their range and occurrence in Hudson Bay. Finally, an assessment of beluga behaviour in the presence of whale-watching vessels showed that beluga response to vessels varied but the probability of travelling behaviour was significantly greater with distance from vessels; belugas also appear to be spending more time interacting with vessels now, as compared to 15 years ago when there were fewer whale-watching vessels. The results found through this research are useful in informing climate change implications, marine-protected area boundaries, policy and marine spatial planning, and subsistence harvest management.

Download or read book Ethology and Behavioral Ecology of Odontocetes written by Bernd Würsig and published by Springer. This book was released on 2019-08-02 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book concentrates on the marine mammalian group of Odontocetes, the toothed whales, dolphins, and porpoises. In 23 chapters, a total of 40 authors describe general patterns of ethological concepts of odontocetes in their natural environments, with a strong bent towards behavioral ecology. Examples are given of particularly well-studied species and species groups for which enough data exist, especially from the past 15 years. The aim is to give a modern flavor of present knowledge of ethology and behavior of generally large-brained behaviorally flexible mammals that have evolved quite separately from social mammals on land. As well, the plight of populations and species due to humans is described in multiple chapters, with the goal that an understanding of behavior can help to solve or alleviate at least some human-made problems.