Activity of digestive enzymes of thick-billed guillemot (<Emphasis Type="Italic">Uria lomvia</Emphasis>) and common guillemot (<Emphasis Type="Italic">U. aalge</Emphasis>) invaded by cestodes

Activities of digestive enzymes (proteases, carbohydrases, acid and alkaline phosphatases) are determined in intestinal mucosa of the thick-billed and common guillemots. Comparative analysis of the obtained results is performed for non-infested and for birds infested by cestodes. It has been established that at infestation by cestode Alcataenia armillaris (Cestoda: Tetrabothriidae), activities of carbohydrase and alkaline phosphatase in intestinal mucosa of the thick-billed guillemot decreases. Parasitizing of cestodes Tetrabothrius jaegerskieldi (Cestoda: Tetrabothriidae) in intestine induces a decrease of saccharase activity. There is studied kinetics of desorption of enzymes from digestive-transport surfaces of the bird intestine. Peculiarities of firmness of enzyme fixation are established on the surface of intestinal mucosa of invaded guillemots. According to the obtained data, a decrease of the carbohydrase activities in intestine of infested guillemots is likely to be due to absorption of a part of enzymes hydrolyzing carbohydrates on the surface of cestodes.     

Carbohydrate metabolism parameters in the thick-billed murre (Uria lomvia) infested with Alcataenia armillaris (Cestoda: Dilepididae)

Some aspects of carbohydrate metabolism in noninfested thick-billed murres (Uria lomvia) and those infested with the tapeworm Alcataenia armillaris (Cestoda: Dilepididae) are reported. The findings demonstrate that the intestinal invasion by A. armillaris causes a drop in the activity of digestive enzymes (glycosidases and sacharase) and decreases blood glucose levels and glycogen content in the liver. The main reasons underlying changes in avian carbohydrate metabolism in cestode invasion are suggested.     

Cryptic introgression between murre sister species (Uria spp.) in the Pacific low Arctic: frequency, cause, and implications

As southern species undergo northward range expansions, reports of hybridization between temperate and arctic taxa are increasing, which may have important implications for the evolution, conservation, and management of arctic species. The extent of hybridization between temperate common murres (Uria aalge) and arctic thick-billed murres (U. lomvia), seabirds in the family Alcidae, has been the subject of debate. In a previous survey of variation in mitochondrial DNA (mtDNA) in common and thick-billed murres sampled from throughout the North Pacific and low Arctic, 12 of 327 common murres (~4%) were found to possess DNA sequences characteristic of thick-billed murres. In the present study, we surveyed variation in three nuclear introns in 230 common murres and 56 thick-billed murres and report that these putative hybrids carry various combinations of intron alleles from common and thick-billed murres. Analysis using the program STRUCTURE indicated that nine of these individuals possessed high proportions of thick-billed murre intron alleles, two possessed alleles in F1 and F2 proportions, and one individual possessed predominantly common murre intron alleles. We propose that the asymmetric mtDNA introgression we observed is most likely the result of mate choice at mixed colonies based on differences in male mating behaviours. Our results highlight that hybridization between thick-billed and common murres is more prevalent than previously thought, which may have important implications for the conservation and management of arctic-dwelling thick-billed murres as common murres expand northward.     

Development and Validation of a Wing Key to Improve Harvest Management of Alcids in the Northwest Atlantic

Abstract: Murres (thick-billed [Uria lomvia] and common [U. aalge]) are legally hunted along the coast of Newfoundland and Labrador, Canada. Razorbills (Alca torda) are also incidentally taken. Only irregular estimates of the total murre harvest are available, so a tool to derive estimates of age- and species-specific harvest is required to effectively monitor the hunt and manage a sustainable harvest. We collected 293 murre and razorbill wings from hunters between 1999–2004, with the goal of identifying wing characteristics that could be used to discriminate age and species. We found that murres and razorbills could be reliably aged (first-yr vs. older) on the basis of molt limits of greater wing coverts. Using a discriminant function (DF) incorporating length of the first primary and second secondary feather, we classified 95–96% of common murres and 99–100% of thick-billed murres correctly to species. First-year thick-billed and common murres also differed in number of pale secondary coverts (median = 12 and 3, respectively), providing another species-specific trait. We developed a key to age and assign species based on these results. We assessed applicability and accuracy of the wing-key with novice observers, who differentiated between murre and razorbill wings using feather-pattern coloration with high accuracy (95 ± 9%) and were able to differentiate between the 2 murres species using 3 techniques: visual assessment of wing shape (83 ± 14% accuracy), the DF (94 ± 6%), and number of worn secondary coverts for first-year birds only (83 ± 5%). Experience increased success rates of aging and species classification using wing shape and number of worn secondary coverts but not using the DF. Despite differences in measurement accuracy and repeatability among observers, the DF proved to be robust. Our results will facilitate implementation of a species composition survey for the murre hunt and will improve identification rates of carcasses found during beached bird surveys in the Northwest Atlantic, aiding in monitoring of alcid populations vulnerable to anthropogenic activities.     

Peculiarities of protein hydrolysis on the digestive-transport surfaces of the intestine of the Kittiwake Rissa Tridactyla and Alcataenia Larina (Cestoda, Dilepididae) parasitizing it

Research of the activity of proteolytic enzymes functioning on the digestive-transport surfaces of the intestine of infected and noninfected kittiwakes Rissa tridactyla and cestodes Alcataenia larina (Cestoda, Dilepididae) parasitizing it was conducted. The protease activities depending on the pH values in the intestine of gulls and tapeworms were determined. The dynamics of desorption of enzymes of protein hydrolysis from the surface of the cestodes A. larina and the kittiwake intestine was studied. It was shown that the tapeworm invasion activates the processes of membrane and cavitary digestion of birds. It was determined that the degree of influence of the dilepidid infection on protease activity was defined mainly by the intensity of the invasion.     

Tissue distribution of lipogenesis in vivo in the common murre (Uria aalge) and the domestic chicken (Gallus domesticus)

1. Total body lipogenesis was similar in the murre and the chicken. 2. The liver contributes 10.4% to whole body lipogenesis in fed murres when measured in vivo using 3H2O. 3. The liver contributes 28.0% to whole body lipogenesis in the fed chicken. 4. The lower contribution of the liver in the murre may be a consequence of the high fat diet of the murre relative to the chicken.     

Effect of Cestodal Infestation on the Distribution Pattern of Digestive Enzyme Activities along the Small Intestine of the Kittiwake (<Emphasis Type="Italic">Rissa tridactyla</Emphasis>)

Activities of digestive enzymes in the intestine of adult and nestling kittiwakes (Rissa tridactyla) were studied. Glycosidase and protease activities in the three parts of the small intestine (proximal, medial and distal) as well as their total activity were determined, and the glycosidase/protease activity ratio (G/P coefficient) was calculated. Enzyme activities were found to be distributed unevenly along the intestine. In a proximal to distal direction, glycosidase and protease activities decrease in nestlings and increase in adult kittiwakes. In nestlings, protease activity values are several times higher than in adults. G/P coefficient values vary within the range of 0.33–0.92 in adult animals and 0.22–0.41 in nestlings. Infestation with tapeworms Alcataenia larina (Cestoda, Dilepididae) and Tetrabothrius erostris (Cestoda, Tetrabothriidae) leads to reduced digestive enzyme activities in the small intestine of kittiwake nestlings. In adult animals, infestation with T. erostris leads to a reduced and with A. larina to an increased protease activity.     

The activities of digestive enzymes as a determinant factor in the localization of <Emphasis Type="Italic">Tetrabothrius erostris</Emphasis> (Loennberg) (Cestoda: Tetrabothriidae) in the intestine of the herring gull <Emphasis Type="Italic">Larus argentatus</Emphasis> Pontoppidan

We determined the parameters of invasion and localization of Tetrabothrius erostris (Loennberg) (Cestoda: Tetrabothriidae) in the intestine of herring gulls Larus argentatus Pontoppidan (adults and nestlings). Adult herring gulls have T. erostris parasites in the proximal and middle segment of their small intestine. Nestlings have T. erostris in the middle segment of their small intestine. High activities of the digestive enzymes (proteases and glycosidaeses) in these segments of the intestine were found. Apparently, this factor, as well as the physiological peculiarities of the development of T. erostris, determine the localization of tetrabothriids in the intestine of herring gulls.     

The effects of variable foraging conditions on common murre (Uria aalge) corticosterone concentrations and parental provisioning

This study investigated how total corticosterone concentrations, chick-feeding rates, and adult body mass changed with food availability from 1998 to 2000 in the same individually marked common murres (Uria aalge). Capelin, the main prey species, arrived inshore by the onset of murre chick hatching in 1998 and 1999 (prey match years); whereas in 2000, hatching began approximately 1 week before the capelin arrived inshore to spawn (prey mismatch year). Serum corticosterone concentrations were higher in the same individuals in the prey mismatch year than they were in either of the match years. Birds sampled before peak capelin spawning in the mismatch year had higher corticosterone levels than murres sampled after peak spawning. Murres with higher corticosterone levels had higher chick-feeding rates and less mass loss in the mismatch year (compared to the match year 1999) than birds with lower levels. Corticosterone levels did not differ between birds that had not foraged for at least 12 h (brooded chick overnight) and those that had, suggesting that short-term food deprivation did not affect corticosterone concentrations. Taken together, these findings suggest that the difference between years reflects a baseline shift in corticosterone levels, particularly in the high-quality birds that were able to increase both corticosterone concentrations and foraging effort.     

Extra-pair matings and mate guarding in the common murre Uria aalge

Forced extra-pair copulations (FEPC) are frequent and mate guarding well developed among common murres. Male murres were at the colony almost continuously through the pre-laying period, but females were present only infrequently, and the frequency of FEPCs was significantly correlated with the relative number of males present. Males vigorously defended their partners from other males and females attempted to resist extra-pair matings. Females whose mates were absent were particularly vulnerable to FEPCs. The number of extra-pair copulations performed by males was estimated to vary between 0–32/season. The reproductive successes of males not performing FEPC, and those performing at the mean and maximum rate are estimated. Males most active in FEPC may substantially increase their reproductive success compared with males not performing FEPC. Ecological conditions in the common murre probably favour prolonged sperm storage, which in turn provides opportunities for sperm competition and favours both effective mate guarding and extra-pair copulations.     

Carbohydrase activities in the bovine digestive tract

1. The carbohydrase activities of homogenates of mucosa from the abomasum, small intestine, caecum and colon, and of the pancreas of cattle were studied. 2. The disaccharidase activities were located mainly in the small intestine and showed a non-uniform pattern of distribution along the small intestine; trehalase activity was highest in the proximal part, lactase and cellobiase activities were highest in the proximal and middle parts and maltase activity was highest in the distal part. 3. The intestinal lactase and cellobiase activities were highest in the young calf and decreased with age, whereas the intestinal maltase and trehalase activities, which were very low compared with the lactase activity, did not change with age. 4. No intestinal sucrase or palatinase activity was detected in the calf or in the adult cow. 5. Homogenates of intestinal mucosa also exhibited amylase and dextranase activity. 6. Homogenates of the pancreas possessed a strong amylase activity and a weak maltase activity. The maltase activity did not change with age, whereas the amylase activity increased with age. 7. No marked differences were observed between the carbohydrase activities of calves fed solely on milk and those of calves given a concentrate-hay diet from 6 weeks of age.     

Multicomponent shell traits are consistent with an individual recognition function of the appearance of common murre (Uria aalge) eggs: A biological replication study

In dense breeding colonies, and despite having no nest structure, common murres (or guillemots: Uria aalge) are still able to identify their own eggs. Each female murre''s egg is thought to be recognized individually by the shell''s avian‐perceivable traits. This is because the eggshells’ visible traits conform to expectations of the identity‐signaling hypothesis in that they show both high intraindividual repeatability and high interindividual variability. Identity signaling also predicts a lack of correlation between each of the putative multicomponent recognition traits, yielding no significant relationships between those eggshell traits that are generated by mutually exclusive physiological factors. Using a multivariate analysis across eggshell size and shape, avian‐perceivable background coloration, spot (maculation) shape, and spot density, we detected no unexpected statistical correlations between Icelandic common murre egg traits lacking known physiological or mathematical relationships with one another. These results biologically replicate the conclusions of a recent eggshell trait study of Canadian common murres using similar methodology. We also demonstrate the use of static correlations to infer identity signaling function without direct behavioral observations, which in turn may also be applied to rare or extinct species and provide valuable insight into otherwise unknown communicative and behavioral functions.     

Benefits and costs of rapid growth in common murre chicks Uria aalge

While accelerated growth can be advantageous to nestling birds, there may be a tradeoff between rapid growth and resistance to food shortages. Common murres Uria aalg e are colonial seabirds that benefit from reproductive synchrony. Individuals that lay eggs late should benefit if they produce chicks capable of growing quickly and fledging synchronously with their neighbors. In this study, we controlled food provisioning of captive-hatched common murre chicks from a single subcolony and examined differences in growth between early-hatched individuals and their later-hatched neighbors. We assessed potential costs of rapid growth by comparing growth of chicks fed ad libitum with their growth under food restricted conditions. Chicks that hatched later were heavier, ate more and gained body mass more quickly than chicks that hatched earlier. Late-hatched chicks grew quickly enough to reach the same mass as their early-hatched neighbors in five days. However, chicks that grew more quickly under ad libitum food conditions grew more slowly when food was restricted. We conclude that murres that lay eggs late may synchronize their reproduction with early-laying neighbors by producing rapidly growing chicks. However, the ability to compensate for late hatching by growing quickly can be costly when food becomes limited.     

Hydrolytic activity of symbiotic microflora enzymes in pike (<Emphasis Type="Italic">Esox lucius</Emphasis> L.) intestines

This study has revealed the existence of microflora which is, to different degrees, associated with the intestinal mucosa of pike. A total of 82 bacterial strains have been isolated. These microorganisms produce enzymes that hydrolyze the major food substrates (proteins and carbohydrates). These enzymes are produced by the pool of various microorganisms living in the intestines, as well as by separate strains isolated in pure cultures. These strains produce enzymes with different levels of activity. Most of the isolated strains (68%) produce proteases. The calculated values of the C/P factor (the ratio of carbohydrase to protease activity) indirectly testify to the autochthonous nature of the microflora associated with the intestinal mucosa of pike. Presumably, the contribution that the microflora enzymes make to the enzymatic activity of the pike intestine is substantial, but it is difficult to estimate now.     

Relative importance of human activities and climate driving common murre population trends in the Northwest Atlantic

Seabird populations are affected by environmental and anthropogenic influences on a global scale. Many population-level responses to climate change have been shown, yet few studies have addressed the additive and/or relative impact of environmental and anthropogenic influences on seabird populations. Using a mixed model approach, we analyzed the trends in plot counts of common murres (Uria aalge) from a Low Arctic colony at Cape St. Mary’s, Newfoundland, across 26 years (1980–2006). We tested for associations between population change and various environmental and anthropogenic covariates: water temperature, winter North Atlantic Oscillation, hunting mortality, oil pollution, by-catch in fishing gear, and visitor disturbance. The number of murres occupying central plots decreased from 1980 to 1989 and increased from 1990 to 2006. Annual changes in the population were negatively associated with the estimated number of murres killed in the Newfoundland murre hunt and the high numbers killed in the early 1980s likely caused the observed population decline. The large number of gillnets set in Newfoundland waters during the 1980s, and associated incidence of drowning through by-catch, probably also contributed to the observed decline. Though a centennially significant cold-water perturbation in 1991 forced a regime shift in pelagic food webs, the effect of ocean climate variability on the population was not obvious. We conclude that management efforts should focus on assessing and mitigating the effects of human-induced influences and consider the potential additive effects of climate change.     

Diving metabolism and thermoregulation in common and thick-billed murres

The diving and thermoregulatory metabolic rates of two species of diving seabrid, common (Uria aalge) and thick-billed murres (U. lomvia), were studied in the laboratory. Post-absorptive resting metabolic rates were similar in both species, averaging 7.8 W·kg^-1, and were not different in air or water (15–20°C). These values were 1.5–2 times higher than values predicted from published allometric equations. Feeding led to increases of 36 and 49%, diving caused increases of 82 and 140%, and preening led to increases of 107 and 196% above measured resting metabolic rates in common and thick-billed murres, respectively. Metabolic rates of both species increased linearly with decreasing water temperature; lower critical temperature was 15°C in common murres and 16°C in thick-billed murres. Conductance (assuming a constant body temperature) did not change with decreasing temperature, and was calculated at 3.59 W·m^-2·^oC^-1 and 4.68 W·m^-2·^oC^-1 in common and thick-billed murres, respectively. Murres spend a considerable amount of time in cold water which poses a significant thermal challenge to these relatively small seabirds. If thermal conductance does not change with decreasing water temperature, murres most likely rely upon increasing metabolism to maintain body temperature. The birds probably employ activities such as preening, diving, or food-induced thermogenesis to meet this challenge.Abbreviations ADL aerobic dive limit - BMR basal metabolic rate - FIT food-induced thermogenesis - MHP metabolic heat production - MR metabolic rate - PARR post-absorption resting rate - RMR resting metabolic rate - RQ respiratory quotient - SA surface area - STPD standard temperature and pressure (25°C, 1 ATM) - T _a ambient temperature - T _b body temperature - T _IC Iower critical temperatiure - TC thermal conductance - V oxygen consumption rate - W body mass     

Characteristics of the effect of cestodes parasitizing the fish intestine on the activity of the host proteinases

The activity and spectrum of proteinases in the intestines of host fishes change upon infestation with cestodes. Serine proteinases are found to make a greater contribution to the total proteolytic activity. The reduction of proteolytic activity is associated with adsorption of the enzymes of the host on the surface of cestodes, and the increase in the activity is caused by the injury of the intestinal mucosa by the attachment apparatuses of cestodes. The inhibition of proteainase activity indicates the possible participation of microbiota enzymes in protein hydrolyses.     

Effect of <Emphasis Type="Italic">Caryophyllaeus laticeps</Emphasis> (Cestoda,Caryophyllidea) upon activity of digestive enzymes in bream

The activities of the main digestive hydrolases were comparatively studied in bream infected and noninfected with cestodes Caryophyllaeus laticeps (Pallas, 1781). It was shown that enzyme activities are distributed in the fish intestine in an irregular manner; the gradient of protease and lipase activities along the gut is presented. Following the infection of bream by cestodes, the activities of the studied enzymes decreased and the percentages of activities of various proteinase subclasses changed. No relation between the distribution of worms along the intestine and the levels of activities of digestive hydrolases was revealed.     

Natural pox infection in a common murre (Uria aalge).

Natural pox infection occurred in a free-living, immature common murre (Uria aalge) in northern California. Cutaneous and diphtheritic lesions were present. Death of the bird was attributed to respiratory insufficiency and starvation resulting from impairment of breathing and feeding, respectively.     

Gastrointestinal helminths of Cuvier's beaked whales, Ziphius cavirostris, from the western Mediterranean

We examined the gastrointestinal helminth fauna of 2 Cuvier's beaked whales, Ziphius cavirostris, stranded on the Spanish Mediterranean coast. Information regarding intestinal parasites of this species is provided for the first time. Six helminth taxa were identified. Thirty type II larvae of the nematode Anisakis sp. were found in the stomach and the intestine of both hosts; 2 type I larvae of Anisakis sp. were found in the intestine of 1 host. One juvenile of the acanthocephalan Bolbosoma vasculosum was found in the intestine; the metacestode Scolex pleuronectis was found mainly in the terminal colon and the anal crypts of both hosts; adult cestodes of Tetrabothrius sp., which may represent a new species, were collected from the duodenum of 1 host. Composition of the intestinal parasitic community is similar to that of other oceanic cetaceans, which mostly include species of Bolbosoma and tetrabothriids (Cestoda).