Training Captive-Bred or Translocated Animals to Avoid Predators

Abstract: Animal reintroductions and translocations are potentially important interventions to save species from extinction, but most are unsuccessful. Mortality due to predation is a principal cause of failure. Animals that have been isolated from predators, either throughout their lifetime or over evolutionary time, may no longer express appropriate antipredator behavior. For this reason, conservation biologists are beginning to include antipredator training in pre-release preparation procedures. We describe the evolutionary and ontogenetic circumstances under which antipredator behavior may degenerate or be lost, and we use principles from learning theory to predict which elements can be enhanced or recovered by training. The empirical literature demonstrates that training can improve antipredator skills, but the effectiveness of such interventions is influenced by a number of constraints. We predict that it will be easier to teach animals to cope with predators if they have experienced ontogenetic isolation than if they have undergone evolutionary isolation. Similarly, animals should learn more easily if they have been evolutionarily isolated from some rather than all predators. Training to a novel predator may be more successful if a species has effective responses to similar predators. In contrast, it may be difficult to teach proper avoidance behavior, or to introduce specialized predator-specific responses, if appropriate motor patterns are not already present. We conclude that pre-release training has the potential to enhance the expression of preexisting antipredator behavior. Potential training techniques involve classical conditioning procedures in which animals learn that model predators are predictors of aversive events. However, wildlife managers should be aware that problems, such as the emergence of inappropriate responses, may arise during such training.     

Parthenogenetic reproduction of Diaphanosoma celebensis (Crustacea: Cladocera): influence of salinity on feeding, survival, growth and neonate production

 Effect of salinity on the feeding rate and parthenogenetic reproduction of asexual females of the cladoceran Diaphanosoma celebensis Stingelin was studied. Short-term (10 h) grazing experiments were conducted using Isochrysis galbana as feed at 5, 17, 25 and 30 psu salinity. Gut pigment concentration showed a significantly higher rate of feeding at lower salinities. Survival, growth, maturity attainment and neonate production of asexual females reared in the above four test salinities indicated preference for lower salinities (5 and 17 psu). The mean size of adult females decreased from 909 to 593 μm, mean life span from 24 to 5 d, mean neonate production from 12 to 2 and mean size of neonates from 434 to 400 μm as the salinity increased from 5 to 30 psu. Salinity variations also affected the size and age of primiparous females. Resting egg formation and sexual reproduction did not occur at the tested salinities. The results indicate that D. celebensis is adapted to low saline, estuarine environments. Received: 14 January 2000 / Accepted: 24 March 2000     

Genetic differentiation in a pelagic crustacean (Meganyctiphanes norvegica: Euphausiacea) from the North East Atlantic and the Mediterranean Sea

Meganyctiphanes norvegica (M. Sars)is a pelagic crustacean that plays a key role in marine food webs of North Atlantic Ocean and marginal seas. We studied eight population samples collected in the European Atlantic and Mediterranean Sea. By means of single strand conformation polymorphism analysis (SSCP) and direct sequencing, we investigated a segment of 158 base pairs of the mitochondrial gene coding for the subunit 1 of NADH dehydrogenase. We found 12 sequence variants among the 385 individuals studied. Analysis of molecular variance (AMOVA) showed that 14.75% of the total genetic variability was explained by differences between populations, thus indicating absence of panmixia for these populations. Pairwise comparisons revealed three distinct genetic pools: the first one represented by Cadiz Bay, the second one by the Ligurian Sea, and the third one included all the NE Atlantic samples. We also investigated one population from the Alboran Sea (within the Mediterranean basin, east of the Strait of Gibraltar). This population was found to be genetically intermediate between the NE Atlantic samples and the Ligurian sample, suggesting that the restriction to the gene flow is not associated with the Strait of Gibraltar, but possibly with the Oran–Almeria oceanographic front. The present work indicates that M. norvegica, although endowed with a high dispersal capacity because of its pelagic habit, can develop separate breeding units inside the same oceanic basin (the Atlantic). Furthermore, the Ligurian sample should be considered as a distinct evolutionary entity, separated from the Atlantic population. Received: 2 May 1999 / Accepted: 26 November 1999     

Grazing rates of organic matter and living fungal biomass of decaying Spartina alterniflora by three species of salt-marsh invertebrates

 The pathway for the flow of salt-marsh grass production into marsh food-webs is still not well defined. We compared the abilities of three marsh macroinvertebrates [salt marsh periwinkles, Littoraria irrorata (Say) (=Littorina irrorata), salt-marsh coffee-bean snails, Melampus bidentatus (Say); and a talitrid amphipod, Uhlorchestia spartinophila Bounsfield and Heard] to access standing-dead leaves of smooth cordgrass (Spartina alterniflora Loisel). The invertebrates were incubated with naturally-decaying leaves, and the rates of removal of organic matter and living fungal biomass (ergosterol) were measured. The impact of invertebrate activity upon fungal growth rates was measured as rates of fungal-membrane synthesis (incorporation of radioacetate into ergosterol). The removal rates of organic leaf biomass per mg individual biomass were highest for amphipods (700 μg mg⁻¹ d⁻¹) and lowest for periwinkles (90 μg mg⁻¹ d⁻¹), but the relatively large biomass of the snails made their removal rates per individual greater than those of amphipods. Net removal of ergosterol by all three invertebrates was >50% for yellow-brown (early-decay) leaf blades. For fully-brown (advanced-decay) blades, >50% removal of ergosterol was found only for periwinkles; exposure to coffee-bean snails and amphipods resulted in a net ergosterol reduction of ≤20%. The lower net reduction of living fungal biomass by coffee-bean snails and amphipods may have been due to fungal-growth stimulation (2.3-fold stimulation in coffee-bean snails and 1.5-fold stimulation in amphipods). Grazing by periwinkles did not stimulate fungal growth, possibly because of its high intensity. Grazing by these three salt-marsh shredders may affect marsh-grass shoot-decay in different ways. Periwinkles may abbreviate the period of fungal production, and incorporate the decaying material relatively quickly into snail biomass and fecal-pellet rain to the sediments. Coffee-bean snails and amphipods may enhance and prolong fungal production, along with the formation of fecal-pellet rain. All three invertebrates fed preferentially on leaf blades rather than leaf sheaths, and feeding rates of gastropods were higher during the night than during the day. Received: 25 November 1998 / Accepted: 4 November 1999     

Metabolic differences between “demersal” and “pelagic” development of the Antarctic sea urchin Sterechinus neumayeri

 Early development of the Antarctic sea urchin Sterechinus neumayeri was examined under two differ-ent culture regimes: one to simulate development near-bottom (“demersal development”) and the other to simulate the development of embryos in the water column (“pelagic development”). When embryos of both treatments reached the hatching blastula stage at 5 d post-fertilization (−1.5 °C), the blastulae that had undergone demersal development evidenced significant differences (by ANOVA or suitable non-parametric comparison) in the following: a thicker blastoderm layer (12%, P < 0.001), higher ash-free dry weights (19%, P < 0.01), lower mass-specific respiration rates (50%, P < 0.001), higher incorporation rates of ³⁵S-methionine into protein (23%, P < 0.003), and a differential pattern of protein synthesis. When embryos developed demersally, they remained in the jelly-coat material released with the eggs at spawning. Quantitative isolation of this jelly-coat material in S. neumayeri demonstrated that it contained a significant amount of organic matter, 115 ng ash-free dry mass per egg, equivalent to 17% of the egg's initial organic mass. Uptake of external nutrients during embryogenesis may be a significant component of the physiological energetics of this polar invertebrate by allowing the utilization of jelly-coat material released by a female during spawning. Received: 21 April 1999 / Accepted: 5 June 2000     

Simultaneous hermaphroditism in the marine shrimp Lysmata wurdemanni (Caridea: Hippolytidae): an undescribed sexual system in the decapod Crustacea

Simultaneous hermaphroditism with outcrossing, a previously unconfirmed sexual system in decapod crustaceans, is documented in the shrimp Lysmata wurdemanni (Gibbes), using time-lapse video observations on mating in pairs of “female-phase” (FP) individuals. Copulations between FPs resulted in successful spawning and development of embryos. However, female-phase hermaphrodites maintained in isolation were unable to self-fertilize spawned eggs. All smaller individuals possessed characters typical of caridean males, including male gonopores, appendices masculinae, ejaculatory ducts, and cincinnuli on the first pleopods. However, the gonad of these male-phase (MP) individuals was an ovotestis with an undeveloped ovarian portion. FPs, which spawn eggs and incubate embryos, also had male gonopores and an ovotestis terminating in ejaculatory ducts containing sperm. In FPs, male pleopod characters were absent or reduced, and a female incubatory character, expanded pleopod flanges, showed a greater relative size. Smaller size classes of the population were composed only of MPs while larger size classes consisted of both MPs and FPs. “Transitionals,” individuals with MP characters but an ovotestis containing vitellogenic oocytes, were rare and overlapped completely in size with FP and larger MP individuals. It is suggested that not all MPs transform into FP hermaphrodites. Social interactions may mediate MP change into FP hermaphrodites in L. wurdemanni. The social system of L. wurdemanni and other Lysmata spp. may determine the exact form of the sexual system in these species. Received: 26 October 1997 / Accepted: 21 April 1998     

Characterization of Organic Compounds in Compost-Amended Soil

Samples of compost-amended soil from waste dumping sites in Lagos Metropolis were extracted with dichloromethane (3 × 20 cm³) and the extract was evaporated at 35 °>C. The residue was extracted with 2,2,4-trimethylpentane, and portions of the solution were applied to a column containing silica gel from which aliphatic and aromatic hydrocarbons were eluted with n-hexane and toluene respectively. Analysis of the n-hexane fraction using gas chromatography showed the presence of a mixture of aliphatic hydrocarbons, ranging from C₉ to C₂₅, while ultraviolet analysis of the toluene fraction suggested 1,2-benzanthracene; 2,3-benzphenanthrene, chrysene and pyrene as polyaromatic compounds present in samples analyzed. The crude extracts were highly coloured and viscous. Total extractable organic residues in the 2,2,4-trimethylpentane extracts ranged from 36 to 89 mg g^-1 of soil.     

Effect of two major N-nitroso hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) metabolites on earthworm reproductive success

Soil and topical tests were employed to investigate the effect of two N-nitroso metabolites of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) on earthworm reproduction. The lowest observed effect concentration (LOEC) for cocoon production and hatching was 50mg/kg for both hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX) in soil. MNX and TNX also significantly affected cocoon hatching in soil (p<0.001) and in topical tests (p=0.001). The LOECs for cocoon hatching were 1 and 10mg/kg for MNX and TNX in soil, respectively, and 10mg/L in the topical test. Greater than 100mg/kg MNX and TNX completely inhibited cocoon hatching. In soil, the EC20 values for MNX were 8.7 and 8.8mg/kg for cocoon and juvenile production, respectively, compared to 9.2 and 9.1mg/kg for TNX, respectively. The EC20 values for the total number of cocoon hatchlings were 3.1 and 4.7mg/kg for MNX and TNX, respectively, in soil and 4.5 and 3.1mg/L in the topical test. Both MNX and TNX inhibited cocoon production and hatching, suggesting that they may have a negative affect on soil ecosystems at contaminated sites.     

Transport of atmospheric fine particulate matter: part 2--findings from recent field programs on the intraurban variability in fine particulate matter

Air quality field data, collected as part of the fine particulate matter Supersites Program and other field measurements programs, have been used to assess the degree of intraurban variability for various physical and chemical properties of ambient fine particulate matter. Spatial patterns vary from nearly homogeneous to quite heterogeneous, depending on the city, parameter of interest, and the approach or method used to define spatial variability. Secondary formation, which is often regional in nature, drives fine particulate matter mass and the relevant chemical components toward high intraurban spatial homogeneity. Those particulate matter components that are dominated by primary emissions within the urban area, such as black carbon and several trace elements, tend to exhibit greater spatial heterogeneity. A variety of study designs and data analysis approaches have been used to characterize intraurban variability. High temporal correlation does not imply spatial homogeneity. For example, there can be high temporal correlation but with spatial heterogeneity manifested as smooth spatial gradients, often emanating from areas of high emissions such as the urban core or industrial zones.