Bringing Home the Trash: Do Colony-Based Differences in Foraging Distribution Lead to Increased Plastic Ingestion in Laysan Albatrosses?

When searching for prey, animals should maximize energetic gain, while minimizing energy expenditure by altering their movements relative to prey availability. However, with increasing amounts of marine debris, what once may have been ‘optimal’ foraging strategies for top marine predators, are leading to sub-optimal diets comprised in large part of plastic. Indeed, the highly vagile Laysan albatross (Phoebastria immutabilis) which forages throughout the North Pacific, are well known for their tendency to ingest plastic. Here we examine whether Laysan albatrosses nesting on Kure Atoll and Oahu Island, 2,150 km apart, experience different levels of plastic ingestion. Twenty two geolocators were deployed on breeding adults for up to two years. Regurgitated boluses of undigestable material were also collected from chicks at each site to compare the amount of plastic vs. natural foods. Chicks from Kure Atoll were fed almost ten times the amount of plastic compared to chicks from Oahu despite boluses from both colonies having similar amounts of natural food. Tracking data indicated that adults from either colony did not have core overlapping distributions during the early half of the breeding period and that adults from Kure had a greater overlap with the putative range of the Western Garbage Patch corroborating our observation of higher plastic loads at this colony. At-sea distributions also varied throughout the year suggesting that Laysan albatrosses either adjusted their foraging behavior according to constraints on time away from the nest or to variation in resources. However, in the non-breeding season, distributional overlap was greater indicating that the energy required to reach the foraging grounds was less important than the total energy available. These results demonstrate how a marine predator that is not dispersal limited alters its foraging strategy throughout the reproductive cycle to maximize energetic gain and how this has led to differences in plastic ingestion.     

Spinner dolphins in a remote Hawaiian atoll: social grouping and population structure

Spinner dolphins (Stenella longirostris) commonly use inshoreisland and atoll habitats for daytime rest and social interactionsand forage over deep waters at night. In Hawaii, they occurthroughout the archipelago. We applied photoidentification mark-recapturetechniques to study the population structure of spinner dolphinsassociated with remote Midway Atoll, far-western Hawaii. AtMidway, spinner dolphins live in stable bisexually bonded societiesof long-term associates, with strong geographic fidelity, noobvious fission-fusion, and limited contacts with other populations.Their large cohesive groups change little over time and arebehaviorally/socially discrete from other spinner dolphin groups.This social pattern differs considerably from the fluid fission-fusionmodel proposed previously for spinner dolphins associated witha large island habitat in the main Hawaiian Archipelago. Thesedifferences correspond to geographic separation and habitatvariation. While in the main islands there are several daytimeresting places available at each island habitat; in far-westernHawaii, areas of suitable habitat are limited and separatedby large stretches of open pelagic waters with potentially highrisk of shark predation. We hypothesize that with deepwaterfood resources in close proximity and other atolls relativelyfar away for easy (day-to-day) access, it is energetically morebeneficial in the remote Hawaiian atolls to remain "at home"than to travel to other atolls, so there is stability insteadof variability; there is no fission-fusion effect. Thus, thegeographic isolation and small size of remote atolls triggera process in which the fluidity of the fission-fusion spinnerdolphin society is replaced with long-term group fidelity andsocial stability.     

A system for restraint and anesthesia in calves

A mobile calf enclosure was developed which incorporated a hydraulic hoist and sling for the care of calves. This apparatus permitted induction of and emergence from anesthesia in an erect posture, which decreased the risk of aspiration and postoperative pulmonary problems. Fifty-two surgical procedures requiring general anesthesia have been performed on 29 calves during the last 2 years with only one operative death, and calves have been maintained within the enclosure for periods up to 1 month.     

Ovulation induction in anestrous bitches by pulsatile administration of gonadotropin-releasing hormone

Preliminary studies in anestrous Beagle bitches demonstrated that a single injection of gonadotropin-releasing hormone (150 micrograms) produced a rapid, physiological rise in serum estradiol lasting 1-3 days while progesterone remained below 1 ng/ml, whereas serial injections of FSH rapidly produced greater elevations in estradiol and a rapid rise in progesterone over 2 ng/ml. Consequently, attempts to induce fertile ovulation by means of pulsatile intravenous administration of GnRH (1 pulse/1.5 hours for 6-12 days; 0.04-0.43 micrograms/kg body weight/pulse) were conducted in eight anestrous bitches. Willingness to mate, serum progesterone levels and results of mating were monitored. In six of the eight bitches, vulval and vaginal signs of proestrus occurred by Day 2-4 after initiation of treatment (Day 0); but, two bitches showed negligible responses. In five of the six bitches in which proestrus was induced, behavioral (n = 4) and vaginal (n = 5) correlates of early estrus occurred by Day 5-7 of treatment and breedings occurred over a period of 4-12 days. Following onset of estrus, four of the five bitches had increases in serum progesterone levels between Days 14 and 18 after initiation of treatment (and 4-11 days after cessation of treatment); three of them became pregnant and whelped normal litters (ranging from 9 to 11 pups). The fifth bitch did not have elevated progesterone during the induced estrus, and upon return to estrus one month later was successfully bred and whelped a normal litter of 10 pups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enzymatic generation of ceramide induces membrane restructuring: Correlated AFM and fluorescence imaging of supported bilayers

The effect of enzymatic generation of ceramide on phase separated bilayers with a mixture of co-existing fluid and liquid-ordered phases has been examined using a combination of atomic force microscopy (AFM) and fluorescence imaging. Supported lipid bilayers prepared from a DOPC/sphingomyelin/cholesterol mixture were imaged prior to, during and after incubation with sphingomyelinase by total internal reflection fluorescence (TIRF) microscopy. Enzyme treatment resulted in the growth of large dye-excluded regions. The growth kinetics for these patches are consistent with activity of a variable number of enzyme molecules in different regions of the bilayer. Correlated AFM and fluorescence imaging shows that some of the large dye-excluded patches form around the original liquid-ordered domains, which become heterogeneous in height with many raised ceramide-rich regions around their periphery. However, some of the dye-excluded patches correspond to areas of the bilayer where the initial domains have largely or partially disappeared. The dye-excluded patches observed by fluorescence are shown to be areas of increased adhesion in lateral deflection AFM images and are postulated to form by incorporation of both cholesterol and ceramide in the original fluid phase and to vary in composition throughout the bilayer. This is evident from the observation that the dye-excluded areas are all detected as areas of increased friction, but do not always show a distinct height difference in topographic images. These results highlight the utility of a multi-modal imaging approach for understanding the complex membrane restructuring that occurs upon enzymatic generation of ceramide.     

Biology,husbandry, and veterinary care of captive Chinese pangolins (Manis pentadactyla)

We report observations on the biology, diet, husbandry, and veterinary care of four adult Chinese pangolins (Manis pentadactyla) maintained at the University of California, San Diego, for 1.5 years; and the births of two baby pangolins. Experience indicates that the minimum requirements for Chinese pangolins is an enclosure 10–12 m², 26°C ambient temperature, a nest box with sand floor, and litter boxes placed in one or two corners of the enclosure for defecation and urination. A diet of two cans of cat food (Science Diet or ZuPreem), 6 tablespoons Esbilac, 2 tablespoons psyllium seed powder, and two raw egg yolks provide adequate nutrition for four pangolins for 1–2 days. Veterinary care should include a complete physical examination of integument and organ systems, determination of blood values, fecal analysis, and treatment with the anthelmintic thiabendazole for elimination of internal parasites. Parasites observed in the four pangolins included Strongyloides, hookworms, filarial nematodes (species unidentified), and nematodes of the genus Cylicospirura. The baby pangolins were born in November (male) and February (female), weighed 93 g and 92 g at birth, and lived 1 and 5 days, respectively. All adult pangolins observed strictly nocturnal behavior patterns.