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USGS2021

Life-history theory provides a framework for detecting resource limitation: A test of the Nutritional Buffer Hypothesis

For ungulates and other long-lived species, life-history theory predicts that nutritional reserves are allocated to reproduction in a state-dependent manner because survival is highly conserved. Further, as per capita food abundance and nutritional reserves decline (i.e., density dependence intensifies), reproduction and recruitment become increasingly sensitive to weather. Thus, the degree to which weather influences vital rates should be associated with proximity to nutritional carrying capacity—a notion that we refer to as the Nutritional Buffer Hypothesis. We tested the Nutritional Buffer Hypothesis using six moose ( Alces alces ) populations that varied in calf recruitment (33–69 calves/100 cows). We predicted that populations with high calf recruitment were nutritionally buffered against the effects of unfavorable weather, and thus were below nutritional carrying capacity. We applied a suite of tools to quantify habitat and nutritional condition of each population and found that increased browse condition, forage quality, and body fat were associated with increased pregnancy and calf recruitment, thereby providing multiple lines of evidence that declines in calf recruitment were underpinned by resource limitation. From 2001 to 2015, recruitment was more sensitive to interannual variation in weather (e.g., winter severity, drought) and plant phenology (e.g., duration of spring) for populations with reduced browse condition, forage quality, and body fat, suggesting these populations lacked the nutritional reserves necessary to buffer demographic performance against the effects of unfavorable weather. Further, average within-population calf recruitment was determined by regional climatic variation, suggesting that the pattern of reduced recruitment near the southern range boundary of moose stems from an interaction between climate and resource limitation. When coupled with information on habitat, nutrition, weather, and climate, life-history theory provides a framework to estimate nutritional limitation, proximity to nutritional carrying capacity, and impacts of climate change for ungulates.

Colorado, Utah, Wyoming↗

USGS2018

Land management alters traditional nutritional benefits of migration for elk

Ungulates typically migrate to maximize nutritional intake when forage varies seasonally. In western North America, however, increasing numbers of ungulates reside on low-elevation winter range year-round rather than migrating. These residents often occupy irrigated agricultural areas, but it is not known whether the nutrition provided by agricultural land exceeds that gained by migration. We evaluated the nutrition available to a partially migratory population of elk ( Cervus canadensis ) in west-central Montana where some individuals summered on low-elevation agricultural lands, whereas others summered on traditional higher-elevation ranges. We sampled elk forage plants from ground plots and adult female elk movements from global positioning system (GPS) collar locations during late summer for 2 years. We tested for differences in the nutrition provided by 11 vegetative communities commonly available to elk in the Rocky Mountains and the nutrition available in areas used by individuals whose behaviors ranged from residency to migration. We found the nutrition available to elk decreased along the continuum from resident to migratory behavior, contrary to our hypothesis that all behaviors would provide access to equivalent forage quality. The relatively small summer home ranges of migrants suggest other factors (e.g., decreased competition) may compensate for their lower nutritional value, because the size of a home range is often inversely related to its fitness benefits. We found irrigated agriculture provided the highest forage quality in low elevations, but recently burned (1–6 yr prior) dry forests at higher elevations provided forage quality approximately equivalent to that of irrigated agriculture. Excluding elk from irrigated agricultural areas should therefore reduce nutritional incentives for elk to reside at low elevations year-round. Additionally, fire in higher-elevation dry forests may temporarily increase forage quality for elk and improve nutritional benefits of migratory behavior. Our results indicate land management practices can affect nutritionally mediated fitness benefits of differing behaviors in partially migratory populations of ungulates

Montana↗

USGS2025

An analytical approach to explore prospects and limits of nutrition-sensitive fisheries governance under climate change

Researchers and policymakers increasingly recognize the contribution of aquatic food systems, such as fisheries, to food security and nutrition. Yet governing fisheries for nutrition objectives is complicated by the multiple overlapping processes that shape availability and access to nutrients over time, including fishing sustainability, climate change, trade dynamics, and consumer preferences. Anticipating the effect of governance interventions to sustain or enhance nutritional benefits from fisheries entails accounting for these multiple interacting influences. We develop an analytical approach to link available data on aquatic foods production, nutrition, distribution, and potential climate impacts to evaluate the nutrition implications of fishery management and post-harvest allocation interventions. We demonstrate this approach using national and publicly available datasets for five case study countries: Peru, Chile, Indonesia, Sierra Leone, and Malawi. As examples, we evaluate the potential to enhance domestic supply of key nutrients to nutritionally-vulnerable populations by (a) dynamically adjusting fishing effort in response to climate impacts on fish stocks, and (b) retaining aquatic foods currently diverted via trade or foreign fishing. The results indicate substantial differences across countries in terms of anticipated climate change effects, with potential for substantially increased nutrition yield in Chile and Peru under adaptive management, vs more modest yield increases in Indonesia. The impacts of post-harvest allocation policies related to foreign fishing, exports, fishing sector, and subnational trade also vary, with exports weighing heavily on nutrient availability in Sierra Leone. This methodological approach represents a step toward operationalizing calls to manage fisheries as part of national food and nutrient supplies, in light of climate change risks.

Environmental Research: Food Systems↗

USGS2010

Ranking Alaska moose nutrition: Signals to begin liberal antlerless harvests

We focused on describing low nutritional status in an increasing moose ( Alces alces gigas ) population with reduced predation in Game Management Unit (GMU) 20A near Fairbanks, Alaska, USA. A skeptical public disallowed liberal antlerless harvests of this moose population until we provided convincing data on low nutritional status. We ranked nutritional status in 15 Alaska moose populations (in boreal forests and coastal tundra) based on multiyear twinning rates. Data on age-of-first-reproduction and parturition rates provided a ranking consistent with twinning rates in the 6 areas where comparative data were available. Also, short-yearling mass provided a ranking consistent with twinning rates in 5 of the 6 areas where data were available. Data from 5 areas implied an inverse relationship between twinning rate and browse removal rate. Only in GMU 20A did nutritional indices reach low levels where justification for halting population growth was apparent, which supports prior findings that nutrition is a minor factor limiting most Alaska moose populations compared to predation. With predator reductions, the GMU 20A moose population increased from 1976 until liberal antlerless harvests in 2004. During 1997–2005, GMU 20A moose exhibited the lowest nutritional status reported to date for wild, noninsular, North American populations, including 1) delayed reproduction until moose reached 36 months of age and the lowest parturition rate among 36-month-old moose (29%, n = 147); 2) the lowest average multiyear twinning rates from late-May aerial surveys ( x̄ = 7%, SE = 0.9%, n = 9 yr, range = 3–10%) and delayed twinning until moose reached 60 months of age; 3) the lowest average mass of female short-yearlings in Alaska ( x̄ = 155 ± 1.6 [SE] kg in the Tanana Flats subpopulation, up to 58 kg below average masses found elsewhere); and 4) high removal (42%) of current annual browse biomass compared to 9–26% elsewhere in boreal forests. When average multiyear twinning rates in GMU 20A (sampled during 1960–2005) declined to <10% in the mid- to late 1990s, we began encouraging liberal antlerless harvests, but only conservative annual harvests of 61–76 antlerless moose were achieved during 1996–2001. Using data in the context of our broader ranking system, we convinced skeptical citizen advisory committees to allow liberal antlerless harvests of 600–690 moose in 2004 and 2005, with the objective of halting population growth of the 16,000–17,000 moose; total harvests were 7–8% of total prehunt numbers. The resulting liberal antlerless harvests served to protect the moose population's health and habitat and to fulfill a mandate for elevated yield. Liberal antlerless harvests appear justified to halt population growth when multiyear twinning rates average ≤10% and ≥1 of the following signals substantiate low nutritional status: <50% of 36-month-old moose are parturient, average multiyear short-yearling mass is <175 kg, or >35% of annual browse biomass is removed by moose.

Journal of Wildlife Management↗

USGS1994

Physiological responses of Yellowstone bison to winter nutritional deprivation

Because nutrition is critically related to other aspects of bison ( Bison bison ) ecology, and the winter ranges inhabited by bison in Yellowstone National Park (YNP) are ecologically diverse, it was important to determine if nutritional deprivation differences occurred among winter ranges. We used chemistry profiles of urine suspended in snow to compare nutritional deprivation of bison from January to April 1988 on 4 sampling areas of 3 winter ranges in YNP. Declining (P < 0.001) trends of urinary potassium: creatinine ratios in bison on all 4 sampling areas indicated progressive nutritional deprivation through late March. Concurrent increases (P ≤ 0.001) in mean urea nitrogen: creatinine ratios from late February through late march in 3 of 4 areas suggested that increased net catabolism was occurring. Diminished creatinine ratios of sodium and phosphorus reflected low dietary intake of these minerals throughout winter. Mean values and trends of urinary characteristics indicated nutritional deprivation varied among 3 winter ranges in YNP. Continued physiological monitoring of nutritional deprivation, along with detailed examination of other aspects of the bison's ecology, will provide greater insight into the role of ungulate nutrition in the dynamics of such a complex system and improve management.

Journal of Wildlife Management↗

USGS1988

Nutritional values of waterfowl foods

wetland habitats throughout their annual cycles. Survival, reproduction, and growth are dependent on the availability of foods that meet nutritional requirements for recurring biological events. These requirements occur among a wide variety of environmental conditions that also influence nutritional demands. Recent work on nesting waterfowl has identified the female’s general nutrient needs for egg laying and incubation. Far less is known about nutritional requirements for molt and other portions of the life cycle, particularly those during the nonbreeding season. Although information on specific requirements for amino acids and micronutrients of wild birds is meager, the available information on waterfowl requirements can be used to develop waterfowl management strategies. For example, nutrient content of foods, nutritional requirements of waterfowl, and the cues waterfowl use in locating and selecting foods are all kinds of information that managers need to encourage use of habitats by feeding waterfowl. Waterfowl nutritional needs during the annual cycle and the nutritional values of natural foods and crops will be discussed below.

Fish and Wildlife Leaflet↗

USGS2021

Juvenile moose stress and nutrition dynamics related to winter ticks, landscape characteristics, climate-mediated factors and survival

Moose populations in the northeastern United States have declined over the past 15 years, primarily due to the impacts of winter ticks. Research efforts have focused on the effects of winter tick infestation on moose survival and reproduction, but stress and nutritional responses to ticks and other stressors remain understudied. We examined the influence of several environmental factors on moose calf stress hormone metabolite concentrations and nutritional restriction in Vermont, USA. We collected 407 fecal and 461 snow urine samples from 84 radio-collared moose calves in the winters of 2017–2019 (January–April) to measure fecal glucocorticoid metabolites (fGCM) concentrations and urea nitrogen:creatinine (UN:C) ratios. We used generalized mixed-effects models to evaluate the influence of individual condition, winter ticks, habitat, climate and human development on stress and nutrition in calf moose. We then used these physiological data to build generalized linear models to predict calf winter survival. Calf fGCM concentrations increased with nutritional restriction and snow depth during adult winter tick engorgement. Calf UN:C ratios increased in calves with lighter weights and higher tick loads in early winter. Calf UN:C ratios also increased in individuals with home ranges composed of little deciduous forests during adult winter tick engorgement. Our predictive models estimated that winter survival was negatively related to UN:C ratios and positively related to fGCM concentrations, particularly in early winter. By late March, as winter ticks are having their greatest toll and endogenous resources become depleted, we estimated a curvilinear relationship between fGCM concentrations and survival. Our results provide novel evidence linking moose calf stress and nutrition, a problematic parasite and challenging environment and winter survival. Our findings provide a baseline to support the development of non-invasive physiological monitoring for assessing environmental impacts on moose populations.

Vermont↗

USGS2017

The nexus of fun and nutrition: Recreational fishing is also about food

Recreational fishing is a popular activity in aquatic ecosystems around the globe using a variety of gears including rod and line and to a lesser extent handlines, spears, bow and arrow, traps and nets. Similar to the propensity to engage in voluntary catch-and-release, the propensity to harvest fishes strongly varies among cultures, locations, species and fisheries. There is a misconception that because recreational fishing happens during non-work (i.e. leisure) time, the nutritional motivation is negligible; therefore, the role of recreational fishing in supporting nutrition (and thus food security) at regional, national or global scales is underappreciated. We consider the factors that influence whether fish will be harvested or released by examining the motives that underlie recreational fishing. Next, we provide an overview of the magnitude and role of recreational fishing harvest in supporting nutrition using regional case-studies. Then, we address issues such as contaminants and parasites that constrain the ability of fish harvested by recreational fishers to be consumed. Although recreational fishing is foremost a leisure activity, the harvest of fish for personal consumption by recreational fishers has contributed and will continue to contribute to human nutrition by providing an accessible, affordable and generally highly sustainable food source, notwithstanding concerns about food safety and possibly overfishing. Attempts to better quantify the role of fish harvested by recreational fishers and the relative contribution to overall food security and personal nutrition will provide resource managers and policymakers the information needed to guide management activities and policy development.

Fish and Fisheries↗

USGS2014

Nutritional stress affects corticosterone deposition in feathers of Caspian tern chicks

Stressful environmental conditions affect the adrenocortical function of developing animals, which can have consequences for their fitness. Discovery of the avian stress hormone corticosterone (CORT) in feathers has the potential to broaden the application of endocrine research in ecological and evolutionary studies of wild birds by providing a long-term measure of CORT secretion. Mechanisms of CORT deposition in feathers are not well known and few studies have related feather CORT to circulating plasma CORT during feather growth. Our objective was to experimentally test the validity of using feather CORT as a measure of CORT secretion in developing birds experiencing nutritional stress. Caspian tern Hydroprogne caspia chicks were fed ad libitum or restricted (35% less than ad libitum) diets for four weeks. We measured CORT in feathers from these chicks to examine the relationship between feather CORT concentrations and nutritional limitation, circulating plasma CORT, and feather development. We found that feather CORT was higher in controls fed ad libitum than in restricted individuals, despite higher levels of plasma CORT in restricted chicks compared to controls. Feather mass and growth rates were strongly and positively related to feather CORT concentrations in both treatments. This is the first experimental study to show that feather CORT concentrations can be lower in response to nutritional stress, even when plasma CORT concentrations are elevated. Our results indicate that CORT deposition in feathers may be confounded when feather mass and growth rates are compromised by nutritional stress. We conclude that feather CORT can be used for assessing nutritional stress in growing birds, but the direction of response depends on how strongly stress affects feather development.

Journal of Avian Biology↗

USGS2004

Effects of nutritional history on nitrogen assimilation in congeneric temperate and tropical scleractinian corals

The nutritional history of corals is known to affect metabolic processes such as inorganic nutrient uptake and photosynthesis, but little is known about how it affects assimilation efficiency of ingested prey items or the partitioning of prey nitrogen between the host and symbiont. The temperate scleractinian coral Oculina arbuscula and its tropical congener Oculina diffusa were acclimated to three nutritional regimes (fed twice weekly, starved, starved with an inorganic nutrient supplement), then fed Artemia nauplii labeled with the stable isotope tracer 15N. Fed corals of both species had the lowest assimilation efficiencies (36-51% for O. arbuscula, 38-57% for O. diffusa), but were not statistically different from the other nutritional regimes. Fed and starved corals also had similar NU4+ excretion rates. This is inconsistent with decreased nitrogen excretion and reduced amino acid catabolism predicted by both the nitrogen recycling and conservation paradigms. In coral host tissue, ???90% of the ingested 15N was in the TCA-insoluble (protein and nucleic acids) and ethanol-soluble (amino acids/low molecular weight compounds) within 4 h of feeding. The TCA-insoluble pool was also the dominant repository of the label in zooxanthellae of both species (40-53% in O. arbuscula, 50-60% in O. diffusa). However, nutritional history had no effect on the distribution of prey 15N within the biochemical pools of the host or the zooxanthellae for either species. This result is consistent with the nitrogen conservation hypothesis, as preferential carbon metabolism would minimize the effects of starvation on nitrogen-containing biochemical pools. ?? Springer-Verlag 2004.

Marine Biology↗

USGS2005

The adrenocortical response of tufted puffin chicks to nutritional deficits

In several seabirds, nutritional state of a nest-bound chick is negatively correlated with the activity of its hypothalamus-pituitary-adrenal (HPA) axis. Increased corticosterone (cort) secretion has been shown to facilitate changes in behavior that allow hungry chicks to obtain more food from parents. However, if parents are not willing/able to buffer their young from temporary food shortages, increased cort secretion could be detrimental to undernourished chicks. In a system where parents are insensitive to chick demands, low benefits and high costs of activation of the HPA-axis in hungry chicks should lead to a disassociation of the nutritional state of the young and the activity of its HPA-axis. We tested this novel hypothesis for the tufted puffin (Fratercula cirrhata), a seabird with intermittent provisioning of a nest-bound semi-precocial chick. We examined the HPA-axis activity of captive chicks exposed to the following: (1) a short-term (24 h) food deprivation; and (2) an array of prolonged (3 weeks) restrictions in feeding regimens. We found that in response to a short-term food deprivation chicks decreased baseline levels of cort and thyroid hormones. In response to prolonged restrictions, food-limited chicks exhibited signs of nutritional deficit: they had lower body mass, endogenous lipid reserves, and thyroid hormone titers compared to chicks fed ad libitum. However, baseline and maximum acute stress-induced levels of cort were also lower in food-restricted chicks compared to those of chicks fed ad libitum. These results support a major prediction of the study hypothesis that puffin chicks suppress HPA-axis activity in response to short- and long-term nutritional deficits. This physiological adaptation may allow a chick to extend its development in the nest, while eluding detrimental effects of chronic cort elevation.

Hormones and Behavior↗

USGS2004

Nutritional ecology of ursids: A review of newer methods and management implications

The capability to understand the nutritional ecology of free-ranging bears has increased dramatically in the last 20 years. Advancements have occurred because (1) managers and biologists recognized the need to link habitat quality, productivity, and variability with bear movements, home ranges, and demographic parameters like reproductive output, survival, and population growth, and (2) several research teams are using new methods to build on the results of earlier field studies. Our ability to couple new field methods and empirical field research with controlled experiments using captive bears has been central to our increased understanding of bear nutrition. Newer methods include the use of stable isotopes to quantify assimilated diet and nutrient flows within ecosystems, bioelectrical impedance to measure body composition, and naturally occurring mercury to estimate fish intake. Controlled experiments using captive bears have been integral to developing methods, isolating specific variables by controlling the environment, and providing additional nutritional understanding necessary to interpret field observations. We review new methods and apply our increased understanding of bear nutritional ecology to 3 management issues: (1) the importance of salmon ( Oncorhynchus spp.) to brown bears ( Ursus arctos ) in the Pacific Northwest, (2) the consequences of the closure of the Yellowstone garbage dumps to grizzly bears, and (3) the relocation of problem bears.

Ursus↗

USGS2021

Detecting resource limitation in a large herbivore population is enhanced with measures of nutritional condition

Resource limitation at the population level is a function of forage quality and its abundance relative to its per capita availability, which in turn, determines nutritional condition of individuals. Effects of resource limitation on population dynamics in ungulates often occur through predictable and sequential changes in vital rates, which can enable assessments of how resource limitation influences population growth. We tested theoretical predictions of bottom-up (i.e., resource limitation) forcing on moose ( Alces alces ) through the lens of vital rates by quantifying the relative influence of intrinsic measures of nutritional condition and extrinsic measures of remotely sensed environmental data on demographic rates. We measured rates of pregnancy, parturition, juvenile, and adult survival for 82 adult females in a population where predators largely were absent. Life stage simulation analyses (LSAs) indicated that interannual fluctuations in adult survival contributed to most of the variability in λ. We then extended the LSA to estimate vital rates as a function of bottom-up covariates to evaluate their influence on λ. We detected weak signatures of effects from environmental covariates that were remotely sensed and spatially explicit to each seasonal range. Instead, nutritional condition strongly influenced rates of pregnancy, parturition, and overwinter survival of adults, clearly implicating resource limitation on λ. Our findings depart from the classic life-history paradigm of population dynamics in ungulates in that adult survival was highly variable and generated most of the variability in population growth rates. At the surface, lack of variation explained by environmental covariates may suggest weak evidence of resource limitation in the population, when nutritional condition actually underpinned most demographics. We suggest that variability in vital rates and effects of resource limitation may depend on context more than previously appreciated, and density dependence can obfuscate the relationships between remotely sensed data and demographic rates.

Wyoming↗

USGS2005

Nutritional condition of elk in rocky mountain national park

We tested the hypothesis that elk in Rocky Mountain National Park (RMNP) were at ecological carrying capacity by determining herd-specific levels of nutritional condition and fecundity. Ingesta-free body fat levels in adult cows that were lactating were 10.6% (s = 1.7; range = 6.2-15.4) and 7.7% (s = 0.5; range = 5.9-10.1) in November 2001 for the Horseshoe and Moraine Park herds, respectively. Cows that were not lactating were able to accrue significantly more body fat: 14.0% (s = 1.1; range = 7.7-19.3) and 11.5% (s = 0.8; range = 8.6-15.1) for the Horseshoe and Moraine Park herds, respectively. Cow elk lost most of their body fat over winter (April 2002 levels were 3.9% [s = 0.4] and 2.9% [s = 0.4] for the Horseshoe and Moraine Park herds, respectively). Nutritional condition indicated that both Horseshoe Park and Moraine Park elk were well below condition levels elk can achieve on very good-excellent nutrition (i.e., >15% body fat; Cook et al. 2004) and were comparable to other free-ranging elk populations. However, condition levels were higher than those expected at a "food-limited" carrying capacity, and a proportion of elk in each herd were able to achieve condition levels indicative of very good-excellent nutrition. Elk in RMNP are likely regulated and/or limited by a complex combination of density-independent (including significant heterogeneity in forage conditions across RMNP's landscape) and density-dependent processes, as condition levels contradict a simple density-dependent model of a population at ecological carrying capacity.

Western North American Naturalist↗

USGS2026

Nutritional content of phytoplankton communities under ice

The effects of winter environmental conditions on lake ecology can be highly variable. Ice and overlying snow isolate the water below, impeding exchange of materials among water, atmosphere, and the watershed. Even with these limitations, biological communities under the ice can persist, where cold tolerant taxa can be especially abundant. Because many under-ice taxa tend to have a suite of unsaturated lipids that enable them to maintain metabolic function during cold conditions, under-ice biological communities may contain highly nutritious resources for higher level consumers relative to warmer, open-water conditions. To examine the effects of ice presence on under-ice biological productivity and nutritional quality, we aggregated data on under-ice physical, chemical, and biological variables from several existing databases. These data are among the most comprehensive, publicly available environmental and phytoplankton data that can be used to compare under-ice and open-water conditions at the community level. To understand how phytoplankton compositional shifts under ice can precipitate shifts in total algal nutritional content available to consumers relative to open water conditions, we merged characteristic phytoplankton fatty acid profiles with phytoplankton community composition data. Our results suggest that even though photosynthetically active radiation under ice is dramatically reduced by snow cover and opaque ice conditions, algal communities can be highly productive. Furthermore, these under-ice communities tend to be dominated by coldwater taxa, which are associated with elevated essential polyunsaturated fatty acids and reduced saturated fatty acids. Saturated fatty acids tend to be most associated with phytoplankton communities in the summer when cyanobacteria are prevalent, while winter communities tend to be most associated with high polyunsaturated fatty acids. As ice duration and quality continue to shift with increasing temperatures worldwide, phytoplankton assemblages are likely to exhibit altered nutritional profiles that have direct and indirect effects on food webs.

Ecopshere↗

USGS2025

Reframing fish passage prioritization for human nutrition outcomes

Water control infrastructure forms barriers that fragment river habitats, reducing aquatic biodiversity and the ecosystem services it provides. Irrigation infrastructure, for example, although implemented to support food production, highlights problematic trade-offs against wild food systems like inland fisheries which are a critical food resource for tens of millions of people, particularly in tropical countries. To reduce fragmentation at a broad range of barriers, fish passage technology is sometimes implemented to support migrating fish, aided by frameworks designed to prioritize barriers for remediation. This study critically evaluated 93 fish passage barrier prioritization frameworks globally to explore how they could strategically guide fish passage investments in tropical contexts and identify criteria relevant to delivering on nutrition security outcomes. Results showed prioritization frameworks were ill-equipped to support the broader human development goals that may drive fish passage investments in tropical countries, such as supporting human nutrition under United Nations Sustainable Development Goal (SDG) 2: Zero Hunger. Tropical contexts were underrepresented despite substantial recent fish passage investment, whereas temperate and conservation focused frameworks, particularly from North America, dominated. These findings prompt reflection on the inherent biases in fish passage barrier prioritization frameworks and criteria. Improving understanding of and collaboration with local partners to integrate SDG 2 into future prioritization frameworks could improve fish passage infrastructure and help support better nutrition and food production for communities.

Environmental Management↗

USGS1994

Nutritional restriction and acid-base balance in white-tailed deer

We examined the effect of progressive nutritional restriction on acid-base balance in seven captive, adult white-tailed deer ( Odocoileus virginianus ) from 4 February to 5 May 1988 in north central Minnesota (USA). Metabolic acidosis was indicated by low mean blood pH (7.25 to 7.33) in deer throughout the study. Mean urinary pH values declined ( P = 0.020) from a mean (±SE) baseline of 8.3 ± 0.1 to 6.7 ± 0.3 as restriction progressed. Acidemia and aciduria were associated with significant variations in mean blood CO 2 ( P = 0.006) and pO 2 ( P = 0.032), serum potassium ( P = 0.004) concentrations, and with a significant ( P = 0.104) handling date × group interaction in urinary potassium : creatinine values. Mean bicarbonate : carbonic acid ratios were consistently below 20:1 during nutritional restriction. Mean packed cell volume increased ( P = 0.019) and serum total protein decreased ( P = 0.001); thus there was evidence for progressive dehydration and net protein catabolism, respectively. Blood pCO 2 , serum sodium, and urinary sodium : creatinine were stable throughout the study. We propose that acidosis and aciduria are metabolic complications associated with nutritional restriction of white-tailed deer.

Journal of Wildlife Diseases↗

USGS1999

Some preliminary findings on the nutritional status of the Hawaiian spiny lobster ( Panulirus marginatus )

Data on the nutritional status of spiny lobster ( Panulirus marginatus ) were collected on the commercial trapping grounds of Necker Bank, Northwestern Hawaiian Islands, in the summers of 1991, 1994, and 1995. Glycogen levels measured in abdominal tissue of intermolt males were used as an index of nutritional health of the field population. The range of glycogen sampled from wild lobster was less than half the level measured in captive lobster fed to satiation in a previous study. An analysis of covariance identified significant interannual and spatial effects explaining 46% of the variance in the sample of wild lobsters. Most significant was a decline in lobster glycogen levels between samples collected in 1991 and 1994-1995. Seasonal influences on lobster nutrition are unknown and were identified as an obvious direction for future ecological research.

Hawaii↗