Assessing the vulnerability of an assemblage of subtropical rainforest vertebrate species to climate change in south‐east Queensland

Global climate change is a threat to ecosystems that are rich in biodiversity and endemism, such as the World Heritage‐listed subtropical rainforests of central eastern Australia. Possible effects of climate change on the biota of tropical rainforests have been studied, but subtropical rainforests have received less attention. We analysed published data for an assemblage of 38 subtropical rainforest vertebrate species in four taxonomic groups to evaluate their relative vulnerability to climate change. Focusing on endemic and/or threatened species, we considered two aspects of vulnerability: (i) resistance, defined by indicators of rarity (geographical range, habitat specificity and local abundance); and (ii) resilience, defined by indicators of a species potential to recover (reproductive output, dispersal potential and climatic niche). Our analysis indicated that frogs are most vulnerable to climate change, followed by reptiles, birds, then mammals. Many species in our assemblage are regionally endemic montane rainforest specialists with high vulnerability. Monitoring of taxa in regenerating rainforest showed that many species with high resilience traits also persisted in disturbed habitat, suggesting that they have capacity to recolonize habitats after disturbance, that is climate change‐induced events. These results will allow us to prioritize adaptation strategies for species most at risk. We conclude that to safeguard the most vulnerable amphibian, reptile and bird species against climate change, climatically stable habitats (cool refugia) that are currently without protection status need to be identified, restored and incorporated in the current reserve system. Our study provides evidence that montane subtropical rainforest deserves highest protection status as habitat for vulnerable taxa.     

The Pleistocene easternmost distribution in Eurasia of the species associated with the Eemian Palaeoloxodon antiquus assemblage

• 1 The Palaeoloxodon antiquus large‐mammal assemblage was typical of the late middle and late Pleistocene interglacials in Europe. This review examines the assemblage's origins, dispersal and cohesiveness in Eurasia.
• 2 During the more climatically equable middle‐Pleistocene periods, the Palaeoloxodon assemblage (or closely related) species occurred across central Eurasia almost simultaneously. In Central and Western Europe, these species responded to climatic changes together as an unvarying interglacial assemblage, whereas in Eastern Europe and Siberia, they occurred in diverging assemblages. The boundary of the Palaeoloxodon assemblage can be drawn roughly from Poland to Romania.
• 3 In Central and Western Europe this interglacial assemblage last occurred during the Eemian. During this period many of the Palaeoloxodon assemblage species may also have co‐occurred in south‐eastern Europe and, except for Bubalus murrensis and Hippopotamus amphibius, further eastwards. The extinct species of the Palaeoloxodon assemblage disappeared in Siberia and Central Asia prior to Europe and the Caucasus whereas the extant species were already present in their modern distribution areas.
• 4 A quantitative study of faunal associations across Eurasia, following much‐needed comprehensive systematic reviews, would further elucidate the patterns of faunal change associated with local and global climatic changes during the middle to late Pleistocene.

     

A conservation paradox for the 21st century: the European wild rabbit Oryctolagus cuniculus,an invasive alien and an endangered native species

• 1 This review highlights the status of the European wild rabbit Oryctolagus cuniculus, which is threatened within its native range and yet is a highly successful colonizer across its worldwide, introduced range.
• 2 The European wild rabbit is a keystone species in Iberia, and the survival of a range of threatened predator species, including the Iberian lynx Lynx pardinus and Spanish imperial eagle Aquila aldabertii, is dependent upon the restoration of rabbit populations. Although not native to the UK, the rabbit also performs significant ecosystem services for nationally rare UK species, by maintaining short sward heights in heathland and grassland ecosystems, and serving as a prey item for populations of predators.
• 3 We identify the European wild rabbit as an excellent model to demonstrate the wide range of complex effects that an introduced mammalian species may exert on ecosystems to which it has been introduced. These effects include habitat degradation following overgrazing, competition with native mammals and facilitating meso‐predator release and hyperpredation.
• 4 We also show that rabbit eradication from some sites may generate more problems than are solved because of the impacts of trophic cascades stemming from dependence on rabbits by native predator assemblages.

     

Santalum album: Kernel Composition, Morphological and Nutrient Characteristics of Pre-parasitic Seedlings under Various Nutrient Regimes

Omission of all nutrients or individual minerals (N, K, P, S,Ca) from the growth medium of pre-parasiticSantalum album seedlingsproduced significant morphological effects. Compared with fullyfertilized seedlings, shoot and root length, leaf area, leaflength and width, leaf number, internode length, shoot length/rootlength ratio, chlorophyll levels, fresh mass and dry mass wereall reduced; leaf thickness increased and stomatal numbers,petiole lengths, root lengths and haustorial numbers showedvariable but significant responses. Mineral-specific deficiencysymptoms were evident in all omission treatments after 3 months.Treatments in which N, K or all minerals were omitted had thegreatest dwarfing effect and increase in height and leaf numberceased after 3 months: only seedlings with no added nutrients(dependent on kernel nutrition) were healthy. The mineral contentof no-nutrient seedlings approximated that in kernels. The distributionof minerals between plant parts for each treatment is given.K concentrations and K/Ca ratios were relatively high in leavesof seedlings which received treatments containing K, especiallywhen Ca was absent. A high K/Ca ratio may be inherent inS. albumseedlings rather than acquired after subsequent host connection.All fully fertilized seedlings developed haustoria within 3months suggesting readiness for early host attachment. Seedlingsin no-nutrient, no-N, no-K or no-P treatments had fewer haustoria. Santalum album ; Indian sandalwood; sandalwood kernels; sandalwood seedlings; nutrient omission; healthy characteristics; deficiency characteristics     

High rates of net primary production and turnover of floating grasses on the Amazon floodplain: implications for aquatic respiration and regional CO2 flux

We investigated whether rates of net primary production (NPP) and biomass turnover of floating grasses in a central Amazon floodplain lake (Lake Calado) are consistent with published evidence that CO₂ emissions from Amazon rivers and floodplains are largely supplied by carbon from C4 plants. Ground‐based measurements of species composition, plant growth rates, plant densities, and areal biomass were combined with low altitude videography to estimate community NPP and compare expected versus observed biomass at monthly intervals during the aquatic growth phase (January–August). Principal species at the site were Oryza perennis (a C3 grass), Echinochloa polystachya, and Paspalum repens (both C4 grasses). Monthly mean daily NPP of the mixed species community varied from 50 to 96 g dry mass m^?2 day^?1, with a seasonal average (±1SD) of 64±12 g dry mass m^?2 day^?1. Mean daily NPP (±1SE) for P. repens and E. polystachya was 77±3 and 34±2 g dry mass m^?2 day^?1, respectively. Monthly loss rates of combined above‐ and below‐water biomass ranged from 31% to 75%, and averaged 49%. Organic carbon losses from aquatic grasses ranged from 30 to 34 g C m^?2 day^?1 from February to August. A regional extrapolation indicated that respiration of this carbon potentially accounts for about half (46%) of annual CO₂ emissions from surface waters in the central Amazon, or about 44% of gaseous carbon emissions, if methane flux is included.     

Análisis de la distribución geográfica de los anomuros (Crustacea: Decapoda) del Golfo de California,México

The anomuran crabs are important from the biogeographic perspective because of their benthonic behavior in their adult state. For this reason, the present work summarizes the different studies developed to date on these crustaceans within the Gulf of California and reinforces the separation of the zone from others in the Province of Cortéz, or Cortesiana. The Gulf of California is inhibited by seventy-eight species of anomurans, belonging to seven families and twenty-eight genera. The best represented family regarding the number of genera (eleven), species (forty-five) and endemic species (eleven) is the Porcellanidae, followed by the Diogenidae with eight genera, fifteen species and four endemic species. The Gulf of California species are distributed in three large zoogeographical groups in the Eastern Pacific, the main one being the Panamic with an intrusion to the Gulf of 69.23% of the species reported. A second important group is that of the endemic species of the Gulf, with 24.35% of the existing species. The boreal species group with intrusion to the Gulf is present with 6.41%. Within the Californian Gulf, ten different zoogeographical groups are found, which demonstrate the great complexity of anomuran distribution, a product of the evolutionary history of this interior sea.     

A Simplified Overlay Plaque Technic for Evaluating Responses of Small Free-Living Amebae in Grassland Soils*

SYNOPSIS. The responses of amebae and bacteria in a grassland soil were investigated by an overlay plaque technic developed in this laboratory. This procedure, using Aerobacter aerogenes as the food source, allowed convenient assay of significant changes in ameba populations which resulted from additions of nutrient and water. In comparison with controls, when water was added an initial increase occurred in bacterial counts followed by an increase in the numbers of amebae. Upon addition of glucose, ameba populations increased initially and then decreased with time, while populations of bacteria remained constant. The addition of hay resulted in significant increases in populations of bacteria and amebae. Plaque appearance on enumeration plates was most rapid with inocula from nutrient-treated soils. Predominant amebae recovered by this technic were species of Acanthamoeba and Hartmannella. They were estimated to be present in untreated soils at 3.2 × 10³/gram. Ameba feeding experiments were used to evaluate the possible suitability of other bacteria as food. The results indicated that nonpigmented laboratory strains of bacteria were preferred, while pigmented grassland isolates were more rapidly utilized. Small soil amebae appear to be sensitive to minor soil perturbations, and the enumeration procedure developed in this study should aid in following their responses to environmental stresses.     

Clumped distribution patterns in goldenrod aphids: genetic and ecological mechanisms

Abstract.

• 1 The aphids Uroleucon tissoti and U.nigrotuberculatum both exhibit significantly aggregated distribution patterns across clumps of their common host plant Solidago altissima, the tall goldenrod. However, U.nigrotuberculatum is significantly more aggregated than is U.tissoti. We tested the hypothesis that goldenrod genotype-by-U.tissoti genotype interactions for aphid performance characters could partially account for this difference.
• 2 Only one of the characters we measured showed a significant genotype-bygenotype interaction; therefore it is unlikely that such interactions affect the distribution of U.tissoti across goldenrod stems.
• 3 In addition, we found that three environmental variables (genetic variation for resistance to herbivory, host plant morphology, and local host density) affect the degree of aggregation found in both U.tissoti and U.nigrotuberculatum populations.

     

Carbon Dioxide as the Initial Stimulus for Excystation of Eimeria tenella Oocysts*

SYNOPSIS. The stimulus necessary to initiate in vitro excystation of the chicken coccidium Eimeria tenella was provided by exposure of intact sporulated oocysts to an atmosphere of carbon dioxide. This stimulus produced a thinning and indentation at the micropylar region and oocysts became permeable to trypsin and bile. Sporozoites became active and began to escape from sporocysts into the oocyst cavity and then to the outside thru the altered micropyle after incubation in the enzyme-bile mixture. Activation of sporozoites when CO₂-pretreated oocysts were incubated in trypsin and bile, was used as the criterion to determine the number of oocysts responding to the initial stimulus. Thus, activation of sporozoites within intact oocysts was an indirect measurement of the number of oocysts stimulated during CO₂-pretreatment. Approximately 90% of the oocysts contained active sporozoites after 18 hr of pretreatment with carbon dioxide and 8 hr incubation in trypsin and bile at 38 or 41 C, respectively. Pretreatment of oocysts with air, N₂, O₂, or He resulted in 8% or less activation during incubation in trypsin and bile. Approximately 83% of the oocysts responded to the stimulus during 8 hr CO₂-pretreatment at 41 C, whereas at 38 C, 16 hr of pretreatment were required for a similar response. The stimulus did not elicit a response from oocysts held at 23 C during the pretreatment gasphase. No significant difference occurred in number of oocysts containing active sporozoites after sufficient CO₂-pretreatment for maximum stimulation of oocysts and incubation in trypsin and bile at 38 or 41 C.     

Floating meadow epiphyton: biological and chemical features of epiphytic material in an Amazon floodplain lake

SUMMARY. 1. Quantities and the chemical composition of epiphyton on the roots of floating aquatic macrophytes were measured in Lake Calado, an Amazon floodplain lake. Growth of epiphytic algae following physical disturbance and losses of epiphyton due to grazing and storms were investigated.
2. Deposition of silt from invading river water decreased chlorophyll and nutrient content (%C, %N, %P) of epiphyton during rising water. N:P ratios of epiphyton indicated that proximity to the river increased supplies of phosphorus. Attached algal biomass per unit root tissue was higher overall during the falling water period, when light was greater, storms less frequent, and new host plant tissue produced more slowly.
3. Epiphytic algal biomass at the margins of floating meadows exceeded that of the phytoplankton in the open water on a per unit area basis. Increases in attached algal chlorophyll ranged from two- to ten-fold over 1 week. Artificial denudation of roots was followed by rapid regrowth of attached algae, leading, after I week, to four-fold increases in chlorophyll over the pre-denuded state.
4. Wind-blown macrophytes experienced an episodic loss of 70% of epiphytic material in less than 1 h. Particulate material lost from roots grazed by snails included root tissue and contained significantly more carbon than material lost from ungrazed roots.