Impact of resuspended sediment on zooplankton feeding in Lake Waihola, New Zealand

1. Wind‐induced sediment resuspension in shallow lakes affects many physical and biological processes, including food gathering by zooplankton. The effects of suspended sediment on clearance rate were determined for a dominant cladoceran, Daphnia carinata, and calanoid copepod, Boeckella hamata, in Lake Waihola, New Zealand. 2. Animals were incubated at multiple densities for 4 days in lake water containing different amounts of suspended lake sediment. Rates of harvest of major food organisms were determined for each sediment level (turbidity) from changes in net growth rate with grazer density. 3. Daphnia cleared all food organisms 7–40 μm in length at similar rates, but was less efficient in its removal of free bacteria, phytoplankton <7 μm, and large cyanobacterial filaments. Elevation of sediment turbidity from 2 to 10 nephelometric turbidity units (NTU) (63 mg DW L^?1 added sediment) reduced Daphnia clearance of phytoplankton, heterotrophic flagellates and ciliates by 72–100%, and of amoebae and attached bacteria by 21–44%. Further inhibition occurred at higher turbidity. 4. Boeckella hamata removed microzooplankton primarily, rather than phytoplankton. The rate at which it cleared rotifers was reduced by 56% when turbidity was increased from 2.5 to 100 NTU. 5. In the absence of macrozooplankton, algal growth increased with sediment turbidity, suggesting that sediment also inhibits rotifer grazing. 6. As mid‐day turbidity in Lake Waihola is ≥10 NTU about 40% of the time, sediment resuspension may play a major role in moderating energy flow and structuring pelagic communities in this lake.     

Temperament in Rhesus,Long‐Tailed,and Pigtailed Macaques Varies by Species and Sex

Temperament differs among individuals both within and between species. Evidence suggests that differences in temperament of group members may parallel differences in social behavior among groups or between species. Here, we compared temperament between three closely related species of monkey—rhesus (Macaca mulatta), long‐tailed (M. fascicularis), and pigtailed (M. nemestrina) macaques—using cage‐front behavioral observations of individually housed monkeys at a National Primate Research Center. Frequencies of 12 behaviors in 899 subjects were analyzed using a principal components analysis to identify temperament components. The analysis identified four components, which we interpreted as Sociability toward humans, Cautiousness, Aggressiveness, and Fearfulness. Species and sexes differed in their average scores on these components, even after controlling for differences in age and early‐life experiences. Our results suggest that rhesus macaques are especially aggressive and unsociable toward humans, long‐tailed macaques are more cautious and fearful, and pigtailed macaques are more sociable toward humans and less aggressive than the other species. Pigtailed males were notably more sociable than any other group. The differences observed are consistent with reported variation in these species’ social behaviors, as rhesus macaques generally engage in more social aggression and pigtailed macaques engage in more male–male affiliative behaviors. Differences in predation risks are among the socioecological factors that might make these species‐typical behaviors adaptive. Our results suggest that adaptive species‐level social differences may be encoded in individual‐level temperaments, which are manifested even outside of a social context. Am. J. Primatol. 75:303‐313, 2013. © 2012 Wiley Periodicals, Inc.     

A review of age determination methods for the Stoat Mustela erminea

A sample of 166 Stoats collected from Craigieburn Forest Park, Canterbury, New Zealand, was used to assess the usefulness of seven different methods of age determination. All the methods made use of characters which do change with age, but not all are equally good at defining useful age classes. The recommended approach is to use a combination of skull and baculum measurements to identify young animals, followed by counting of the canine cementum annuli of adults. If the skull or baculum is broken or not available, visual assessment of the status of the nasal sutures, the lateral suprasesamoid tubercle of the femur and the wear of the carnassial teeth are the next best options for distinguishing the young. Kopein's index based on the closure of the pulp cavity of the canines, and the zonation visible in the periosteal bone of the mandible, are unreliable.     

Effects of 4-Chloro-2-methylphenoxypropionate (an Auxin Analogue) on Plasma Membrane ATPase Activity in Herbicide-Resistant and Herbicide-Susceptible Biotypes of Stellaria media L.

ATPase activity was examined in plasma membrane (PM) fractionsprepared from mecoprop-resistant and -susceptible biotypes ofStellaria media L. (chickweed). Treatment with the herbicidecaused an 18% increase in ATP hydrolysis, but this was not significantlydifferent from control plants and was similar for both biotypes.However, there was an overall significant biotype effect, herbicide-resistantplants having greater enzyme activity than susceptible ones.Proton-pumping was readily demonstrated in PM fractions obtainedfrom both biotypes using the fluorescent probe amino-chloro-methoxyacridine(ACMA), indicating a relatively large proportion of 'inside-out'vesicles. Proton-pumping was significantly greater in PM preparationsobtained from the resistant compared with susceptible plants.The differences in ATPase activity between the two biotypescould not be attributed to differences in the main sterol orphospholipid components of the PM. There were no effects ofthe herbicide on ATP hydrolysis in vitro, but proton-pumpingwas affected in a herbicide concentration-dependent manner.At 1·0 mol m mecoprop caused an increase in the rateof proton-pumping, whereas at 10 and 100 mol m^–6, an inhibitionin this rate was observed. Both biotypes behaved similarly,irrespective of mecoprop concentration. These data indicatethat mecoprop resistance in chickweed is unlikely to be dueto a direct effect of the herbicide on PM H+-ATPase activity. Key words: Stellaria media, mecoprop, ATPase, plasma membrane, herbicide resistance     

The Role of the Lens in Controlling Heat-induced Breakdown of Testa-imposed Dormancy in Native Australian Legumes

A high proportion of seeds of most species of the Fabaceae havetesta-imposed dormancy, which prevents them from imbibing watereven under favourable environmental conditions. This allowsseeds to accumulate in a persistent soil seed bank. Dormancyis usually considered to be broken only when the testa is disrupted,particularly at the lens. In Mediterranean-type ecosystems,the primary natural mechanism causing the breakdown of thisdormancy is the disruption of testas in the soil seed bank byheat from fires that warms the soil in which the seed bank occurs.We examined experimentally the role of the lens in controllingthis heat-induced breakdown of dormancy in 16 native Australianspecies of the Faboideae and Mimosoideae. Two groups of patternsare recognized: species of the Mimosoideae: Acacieae and Faboideae:Mirbelieae, where water permeability is regulated by the lens;and species of the Faboideae: Bossiaeeae, where water permeabilityapparently occurs at non-localized regions of the testa. Thespecies in these two groups differ in the structure of theirtestas. Thus, testa-imposed dormancy does not represent a singledormancy mechanism in legumes, as is often assumed when dormancyis broken artificially.Copyright 1998 Annals of Botany Company Leguminosae, Fabaceae, seed dormancy, hard-seededness, germination, lens, strophiole, Australia.