Patterns of orientation behavior in marsh frogs (Rana ridibunda Pall.) of southern populations

The behavior of frogs from southern areas with an arid climate released during the reproductive period between their “home” pond and a less distant river is shown to be independent of weather conditions. The experiments were performed on frogs living near the village of Dosang, Astrakhan oblast. The frogs were released 60 to 150 m from their “home” breeding waterbody and 60 to 80 m from an “alien” waterbody. Four experiments were performed on 27 individuals. The movements of the frogs were traced by the method of “tracking by a thread.” The results revealed no preference in the frogs to return to their own breeding ponds, rather than to the nearby river. This behavior is peculiar to frogs of southern populations.     

Effects of submerged plants on water quality and biota in large-scale experimental ponds

We quantitatively studied the effect of submerged plants on water quality and biota under fish-free conditions for 3 weeks in four large freshwater experimental ponds (533 m³ per pond) at the Aqua Restoration Research Center, Japan. Two artificially harvested ponds with scant vegetation were used as “harvested ponds” (H1, H2), and the other two ponds, which were naturally dominated by Hydrilla verticillata, were used as “vegetated ponds” (V1, V2). The PVI (percent water volume infested with macrophytes) was employed as an index of vegetation abundance. Vegetated ponds had much clearer water than harvested ponds. The water quality in H2 (PVI 10%) was better than in H1 (PVI 3%), whereas the water quality did not differ significantly between the two vegetated ponds (V1, PVI 38% and V2, PVI 84%). Therefore, the threshold between clear water and turbidity was between 10 and 38% in PVI. Our result also showed that a turbid water state was created shortly after harvest. Green algae were abundant in the harvested ponds, and diatoms were dominant in the vegetated ponds. Rotifers were stably dominant in the harvested ponds. Aquatic worms were more abundant in the harvested ponds than in the vegetated ponds. Unexpectedly, zooplanktons were much less abundant in the vegetated ponds; therefore, zooplankton grazing was not the main mechanism behind the cleaner water in our experiment. These results are physical evidence that the presence of dense macrophytes was the main factor in the creation of a clear water state.     

The morphometrics and colouration of the European pond turtle Emys orbicularis in Lubuskie province (West Poland)

The European pond turtle Emys orbicularis, is an endangered species in Poland. The region of the Ilanka River, in the western part of the country (Lubuskie province), is the most densely inhabited area by the species. Several populous sites are dispersed over the whole area of the province. Over the past 10 years, 279 turtles were captured at 11 sites. In 218 individuals, those with a straight carapace length (SCL) between 2.10–12.10 cm, sex was not determined; the remaining 61 with SCL 13.33–19.85 cm were sexed. Females had bigger bodies and were heavier than males. The SCL of females was 17.10 ± 1.7 cm (average ± SD, n = 33), their body mass (BM) was 790.6 ± 228.7 g (n = 27), and in the case of males SCL was 15.44 ± 1.5 cm and BM was 554.2 ± 138.8 g (n = 28). SCL of the smallest egg laying female was 15.30 cm, and SCL of the smallest mating male was 13.33 cm. The colouration of the turtles which undergoes change with age can be varied.     

Characterization of the thermal tolerances of forest ants of New England

Characterization of thermal tolerances of ants, which are both abundant and important in most terrestrial ecosystems, is needed since thermal constraints can inform how a species may respond to local climatic change. Here we identified the thermal tolerances of 16 common ant species of the Northeastern United States and determined relationships between body size, desiccation, and thermal tolerance among species. We hypothesized that maximum heat tolerances of these species would differ and be related to body size and capacity to resist desiccation. We identified four distinct groups of species belonging to one of three subfamilies, Dolichoderinae, Formicinae, or Myrmicinae, with different maximum thermal tolerances. Group “a” had a mean thermal tolerance of approximately 43°C (±1°C), group “b” had a mean thermal tolerance of 40°C (±1°C), group “c” had a mean thermal tolerance of 38°C (±0°C), and group “d” had a mean thermal tolerance of 36°C (±0°C). Groups “a” and “d” consisted of a single species (in the subfamilies Myrmicinae and Formicinae, respectively), while groups “b” and “c” were a mix of species in the subfamilies Myrmicinae, Formicinae, and Dolichoderinae. In the subfamily Formicinae, thermal tolerance increased with body size and critical water content, a metric of desiccation tolerance. In contrast, in the subfamily Myrmicinae, higher thermal tolerance was correlated with intermediate body size and lower critical water content. These findings suggest that the two dominant subfamilies in Northeastern deciduous forests have different relationships between body size, capacity to tolerate desiccation, and thermal tolerances across species. This variation in thermal tolerance suggests that climatic change may impact species differently.     

Lesions in thighs from hunted Brown Hares (<Emphasis Type="Italic">Lepus europaeus</Emphasis>) and microflora under vacuum-packaging storage

In two surveys, thighs of a total of 137 hunted hares were tested for the presence of intramuscular shots and femur fractures, which were detected in 42.7% and 29.2% of 274 thighs, respectively. Femur fractures were significantly associated with the presence of intramuscular shots. In the second survey (46 hares), 92 thighs were grouped into three categories, “A” (no fractures, no intramuscular shot), “B” (one intramuscular shot), and “C” (multiple shots and hematoma), with 49.0%, 33.6%, and 17.4%, respectively. Category “C” was found unfit for human consumption. During 7-day storage of vacuum-packed “A” and “B” thighs, total aerobic counts increased from initially 3.3 ± 0.3 (mean ± SD) and 4.1 ± 0.6 log cfu/g by ca. 2 log units when stored at 3–4°C, whereas the increase was clearly <1 log unit at 0°C. In comparison to temperature, differences between “A” and “B” category were less pronounced. Similar dynamics were observed for Enterobacteriaceae. In all categories, muscle pH values (mean = 5.83) were similar. It is concluded that storage at temperatures of ca. 4°C, although in compliance with EU legislation, does not afford keeping microbial contaminants in check, and thus will not preserve microbiological quality of vacuum-packed hare meat.     

Recovery dynamics and viability of the white-tailed eagle (<Emphasis Type="Italic">Haliaeetus albicilla</Emphasis>) in Germany

Understanding the effect of protection measures on recovery of endangered populations is crucial for assessing the efficiency of management plans. Following the ban of DDT, PCB and other detrimental chemicals in the 1970s, the German white-tailed eagle population recovered rapidly. Using nest monitoring data, dead recovery data and population dynamics models, we examined both short and long-term viabilities of the population. Between 1991 and 2005 the proportion of breeding pairs with an active nest among territorial pairs was α = 0.88 ± 0.007. Annual breeding success was γ = 0.62 ± 0.014. Mean fledged brood size was b = 1.50 ± 0.010 fledged/successful breeding pair. The analysis of dead recovery data of 1,273 individuals ringed as nestling between 1991 and 2006 allowed survival rates to be estimated. We needed to distinguish between “young” (5 years old) and “old” (older than 5 years) adults. Furthermore the annual survival rate was higher for juvenile and immature birds (0.921 ± 0.024) than for adults (s _“young” = 0.760 ± 0.097 and s _“old” = 0.875 ± 0.079), a pattern presumably explained by territorial fights. Finally, an age structured model was used to examine the joint effect of population regulation, environmental and demographic stochasticities. All results indicated that only pessimistic scenarios could lead to substantial extinction probabilities within 100 years. We conclude that management measures were successful in removing the main extinction factors of the population and that future conservation efforts need to focus on the remaining ultimate extinction causes.     

Does age matter in studying the crustacean eye?

 Fifty randomly selected publications dealing with aspects of crustacean vision had their Materials and methods sections examined. In half of the articles gleaned, only the name of the animal under study was given; the other half mentioned “adult” or “mature” animals; twelve papers provided information on size or age of the experimental animal and six gave the sex. In Petrolisthes elongatus, rhabdom microvilli not only become more regular in outline as the animal grows, but also decrease in diameter from 90.4±21.2 nm in crabs of 5.0–8.9 mm carapace length via 86.6±13 nm in crabs of 9.0–12.9 mm carapace length to 79.7±7 nm in crabs of 13.0–16.9 mm carapace length. Approximately 400 cross sectional diameters of microvilli from identical regions in four eyes of each size class were measured and provided the basis for Anova-, Levene-, and t-tests. The three size classes possess microvilli of significantly different diameters and standard deviations. Our observations show that investigators of the crustacean photoreceptor have frequently neglected to consider the size of their experimental animals, but that this practice should not be continued as the now documented changes in microvillus diameters may influence the amount of visual pigment present and, thus, the photoreceptor’s sensitivity to light. Accepted: 7 May 1996     

Composition of phytobenthos in “lab-lab”, a periphyton-based extensive aquaculture technology for milkfish in brackishwater ponds during dry and wet seasons

The study compared the species composition of phytoperiphyton (“lab-lab”) present in ponds when gradually filled with water weekly to depths of 5, 10, 15 and 30 cm between the wet and dry seasons, for one month before the stocking of fish was studied. This was done during the dry season (March–April, 2003) and wet season (June–July, 2002). Periphyton was allowed to grow on 24 artificial substrates set at equal distances in a 1000 m² pond. “Lab-lab” that colonized the artificial substrates and that on the pond surrounding the substrates were scraped off from a measured surface area. Simultaneously, water was collected for the analysis of physical, chemical and biological parameters. Sampling was done bi-weekly coinciding with 2 and 7 days submergence at a desired depth before adjusting the water level. The major algae consisted of the diatoms (Bacilliarophyta), the blue green algae (Cyanobacteria), and the green algae (Chlorophyta). The diatoms were dominant during the dry season while the cyanobacteria dominated during the wet season. Twenty eight genera were observed during the dry season and 25 genera were noted in the wet season. Variation in genera and density that were observed every sampling period, was influenced by environmental conditions and the incoming water. The total algal density ranged from 100.7 × 10⁸ – 855.1 × 10⁸ and to 24.7 × 10⁸ – 83.9 × 10⁸ organisms.m⁻² during the dry and wet seasons, respectively. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

“Green water” microalgae: the leading sector in world aquaculture

Freshwater fish culture is generally considered the largest sector in world aquaculture. Several of the leading species consume “green water” plankton. This plankton—mostly microalgae (phytoplankton) and also bacteria, protozoa and zooplankton—grows in man-made fertilized water impoundments. The quantity of “green water” microalgae consumed by fish and shrimp is estimated here at a quarter billion ton fresh weight a year, about three and a half times as much as the entire recognized aquaculture. This estimate is based on the quantities of the microalgae consumed and the efficiencies of their use for growth by the main species in aquaculture. The cost of producing “green water” microalgae by the aquaculturists—mostly in SE Asia—is low. The populations in “green water” are biologically managed by the cultured fish themselves. The fish with their different feeding habits help “manage” the composition of the plankton and the overall water quality as they grow. The aquaculturists further manage “green water” through simple means, including water exchange and fertilization. Cost is remunerated partially by the income from sales of the fish and partially by bio mitigation services that “green water” polyculture ponds provide the aquaculturists in treating farm and household waste. A comprehension of the scale and importance of the microalgae sector to world aquaculture should lead to more research to improve understanding of algal population dynamics, growth factors, and efficiency of food chains. The consequent improved control of the plankton’s interaction with fish and shrimp production in “green water” will undoubtedly contribute much to the expansion in production of seafood.     

Final thermal preference in parthenogenetic females of Daphnia magna straus (Crustacea: Cladocera) acclimated to various temperatures

The final thermal preference FTP) range in parthenogenetic females of cladoceran Daphnia magna was assessed by “acute” and “chronic” methods. The first method included 4-month acclimation to different temperatures in the range of 14.2 ± 0.7 to 27.1 ± 0.3°C; the “chronic” method was characterized by long-term acclimation to +20°C. Two ranges of FTP were found for D. magna, 13.3–15.4°C and 20.2–26.2°C. The thermal preference of daphnids and the temperature of acclimation were correspondingly linearly. The range of FTP was independent of the season. The searching activity of D. magna rose in April, when the FTP range increased, and the FTP was less pronounced.     

Analysis of the growth performance,stress, profile of fatty acids and amino acids and cortisol in Tilapia (Oreochromis niloticus), cultured at high stocking density using in-pond raceway system

In-pond raceway system technology (IPRS) was introduced in Pakistan in 2019 as solution for sustainable aquaculture approach by effectively increasing production, reducing pollution and facilitating feed and pond management. Fingerlings of GIFT Tilapia (Oreochromis niloticus) (n = 16,500 in each raceway, initial weight = 32.00 ± 1.26 g) were stocked in June 2019 in two IPRS raceways (area of each raceway = 220 m³) for 171 days until harvested on November 30, 2019. Fingerlings stocked in traditional earthen ponds (area of each pond = 6167 m³) were studied as control (n = 3000 in each pond, initial weight = 32.00 ± 1.26 g). Average harvested biomass from raceways was 57.33 kg/m³ with an average daily weight gain per fish of 4.47 g per day. On the other hand, average harvested biomass from control ponds was 0.38 kg/m³ with an average daily weight gain per fish of 4.60 g per day. Average feed conversion ratio (FCR) in both raceways and control ponds was recorded as 1.25 and 1.24, respectively. Overall survival rate in both raceways and control ponds was above 99%. No sign of any disease was noted at any stage in both study groups. Crude protein and fats contents did not reduce in any raceway despite of high stocking density and sharp seasonal changes. Profile of essential and non-essential amino acids were found to be upto nutritional requirements of adult human. High levels of n-3 and n-6 fatty acids in fish collected from raceways as compared to those in traditional earthen pond show that muscle quality was not compromised due to high stocking density in small area. Return on investment excluding capital cost was 47.05 which implies that IPRS technology can be economically feasible with further modifications.     

Allozyme variability within and divergence among populations of the liverwortConocephalum conicum (Marchantiales: Hepaticae) in Japan

Genetic variation within, and divergence among, populations of the liverwortConocephalum conicum were estimated from the study of 17 populations and 23 putative gene loci. Two additional multilocus genotypes (“T” and “FS”) were detected in Japan, along with the previously reported “J” type. These three multilocus genotypes differed both morphologically and ecologically. All eight populations from western Japan included only the J-type and exhibited low genetic variation within populations: Nei's (1973) average gene diversity (Ĥ)=0.080±0.029. In contrast, co-occurrence of several multilocus genotypes in each population from the Kanto District resulted in much higher levels of genetic variation (Ĥ=0.218±0.037). If the three genotypes are distinguished,Ĥ values are 0.113±0.030 for T-type, 0.107±0.033 for FS-type, and 0.083±0.018 for J-type. UsingC. japonicum, which showed low genetic variation (0.014±0.010) as an outgroup, each genotype formed a monophyletic clade, and the J- and FS-types were more closely related to each other than to the T-type. Populations of western Japan and the Kanto District also differed in the degree of gene diversity among populations, but the reasons for these differences are obscure.     

Effects of water-depth and water-level fluctuations on the macroinvertebrate community structure in the littoral zone of Lake Constance

This article presents an evaluation of two sampling methods for assessing the biodiversity of heavily vegetated wetlands. The aim was to establish an effective sampling regime to maximise total taxon richness and minimise sampling effort. Three Integrated Constructed Wetland (ICW) systems in Annetown Valley, Co. Waterford, SE of the Republic of Ireland, were sampled during spring and summer 2005. The two methods that were evaluated were pond netting and two types of horizontal activity traps, namely “horizontal activity traps” (HATs) and modified “horizontal activity traps” (modified HATs). The activity traps provided a one-way funnel system and were constructed from 2 l plastic bottles, allowing for the passive collection of taxa. HATs were designed to capture macroinvertebrates in open water and modified HATs, which were designed specifically for this study, were used to sample within stands of dense emergent vegetation. Results show that a combination of pond netting and activity traps will yield a more complete estimate of taxon richness. The performance of Modified HATs was not significantly different from that of the HATs in dense vegetation. Tests on the sampling effort required for each method are also discussed. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: R. Céréghino, J. Biggs, B. Oertli and S. Declerck The ecology of European ponds: defining the characteristics of a neglected freshwater habitat     

Viability selection on body size in a non-marine ostracod

One of the most important research topics in evolutionary ecology is body size evolution. Actually, several hypotheses have been proposed to explain the many observed patterns—also known as “rules”—of body size variation in across latitude, temperature, and time. The temperature–size rule (TSR), describes an inverse relationship between body size and temperature. We took advantage of the “natural laboratory” that the crustacean populations at the Chilean altiplano offers, to study the TSR in ostracods. We studied three populations of Limnocythere atacamae that are physically separated by several kilometers, and differ mainly by their permanent thermal regime. We found larger individuals in the hotspring compared to the cold ponds. Also, in the hotspring we found a significant quadratic selection coefficient, suggesting stabilizing selection in this population. The fitness profiles showed stabilizing selection in the hotspring, and positive directional selection in the ponds. Our results suggest the existence of an optimal body size above the population means. This optimal size is apparently attained in the hotspring population. Then, natural selection appears to be promoting a shift in the mean phenotype that, for some reason, is not attained in the cold environments. Genetic slippage and population bottleneck would explain this absence of response to selection.     

Energy flow and subsidies associated with the complex life cycle of ambystomatid salamanders in ponds and adjacent forest in southern Illinois

Breeding adults and metamorphosing larval amphibians transfer energy between freshwater and terrestrial ecosystems during seasonal migrations and emergences, although rarely has this been quantified. We intensively sampled ambystomatid salamander assemblages (Ambystoma opacum,A. maculatum, and A. tigrinum) in five forested ponds in southern Illinois to quantify energy flow associated with egg deposition, larval production, and emergence of metamorphosed larvae. Oviposition by female salamanders added 7.0–761.4 g ash-free dry mass (AFDM) year⁻¹ to ponds (up to 5.5 g AFDM m⁻² year⁻¹). Larval production ranged from 0.4 to 7.4 g AFDM m⁻² year⁻¹ among populations in three ponds that did not dry during larval development, with as much as 7.9 g AFDM m⁻² year⁻¹ produced by an entire assemblage. Mean larval biomass during cohort production intervals in these three ponds ranged from 0.1 to 2.3 g AFDM m⁻² and annual P/B (production/biomass) ranged from 4 to 21 for individual taxa. Emergent biomass averaged 10% (range=2–35%) of larval production; larval mortality within ponds accounted for the difference. Hydroperiod and intraguild predation limited larval production in some ponds, but emerging metamorphs exported an average of 70.0±33.9 g AFDM year⁻¹ (range=21.0–135.2 g AFDM year⁻¹) from ponds to surrounding forest. For the three ponds where larvae survived to metamorphosis, salamander assemblages provided an average net flux of 349.5±140.8 g AFDM year⁻¹ into pond habitats. Among all ponds, net flux into ponds was highest for the largest pond and decreased for smaller ponds with higher perimeter to surface area ratios (r ² =0.94, P<0.05, n=5). These results are important in understanding the multiple functional roles of salamanders and the impact of amphibian population declines on ecosystems. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Fish recruitment, dispersal, and trophic interactions in a heterogeneous lotic environment

I examine how dispersal of juvenile creek chubs (Semotilusatromaculatus) from beaver ponds into adjacent stream environments interacts with temporal abiotic variability to influence fish foraging, growth, and long-term persistence in the lotic ecosystem. Minnow trapping in upstream and downstream beaver ponds, along with weir traps used to monitor directional movement, indicated that most chubs colonized the stream from the downstream beaver pond. Large annual fluctuations in density of age 0 creek chubs occurred in the stream over a 10-year sampling period. Multiple regression analysis indicated that stream temperature, precipitation, and the density of reproductive creek chubs were not correlated with summer density of age 0 chubs in the stream. The factor most strongly associated with increased density of age 0 creek chubs was creation of the downstream beaver pond during the 6th–7th years of the study, suggesting dispersal from the pond was the primary factor determining age 0 fish density in the stream. Most individuals in the strong year classes neither persisted in the stream through their first winter nor resulted in an increased abundance of older age classes in later years. Comparison of age 0 fish density in summer to the proportion of fish surviving to age 1 in spring suggested that overwinter mortality was density dependent. Furthermore, a comparison of the size structure for age 0 individuals in summer to age 1 individuals the following spring indicated that winter mortality was size dependent. Experiments in an artificial stream adjacent to the natural channel revealed that fish growth was strongly density dependent, decreasing as fish density increased across both spring and summer, and elevated and low discharge. The decline in invertebrate prey captured by the fish and the subsequent decline in fish growth appeared to be particularly pronounced under low discharge in summer. Changes in juvenile creek chub density had no significant effect on benthic insect or crustacean abundance, suggesting that exploitative competition for limited invertebrate drift resources was a more important cause of density- dependent growth than depressed local benthic invertebrate abundance. These results suggest that lotic regions adjacent to beaver ponds act as potential reproductive “sinks” for dispersing juveniles confronting seasonal and flow-mediated restrictions on resource acquisition and growth, and the occurrence of seasonal bottlenecks to their survival, especially harsh winter conditions. Received: 9 September 1996 / Accepted: 8 August 1997     

Identification of cancer stem cells-associated “side population” by flow cytometry with a violet laser

The possibility of identification of a “side population” of cancer stem cells in solid tumors by a flow cytometer equipped with a 405 nm violet laser has been investigated. Ovarian cancer (Skov-3) and colorectal cancer (Colo 320) cell lines formed the “side population” after vital staining with Hoechst 33342. Analysis of cells isolated from the tumor tissue of malignant melanoma and colorectal cancer, also revealed the “side population” characterized by increased fluorescent dye exclusion. The percentage of melanoma cells included in the “side population” was the same as that of cells co-expressing the cancer stem cells markers CD34 and CD44. However, the colon cancer “side population” was significantly smaller than the minor populations of colon cancer cells identified by either CD133 expression or exclusion of Rhodamine 123 exclusion.     

Landscape connectivity affects individual survival in unstable patch networks: The case of a freshwater turtle inhabiting temporary ponds

1. The loss of connectivity is among the main threats for species occupying freshwater pond networks. Landscape connectivity can impact the persistence of patchy populations by reducing movement rates among ponds, thereby increasing the likelihood of local extinctions in source–sink systems, and reducing the probability of colonisation following extinctions. In addition, loss of connectivity may also reduce survival rates if individuals have to cross a hostile matrix, though this hypothesis has been rarely tested. Here, we address these issues by evaluating how individual survival and inter-patch movement probabilities of the European pond turtle (Emys orbicularis) are influenced by patch connectivity.
2. The study was carried out in a network of temporary ponds embedded in a heterogeneous agricultural matrix in southwestern Portugal, encompassing a period associated with a severe drought (2003–2005) and another with wetter climatic conditions (2010–2014). We mapped the location of ponds and land uses around each pond, and quantified connectivity among ponds using least-cost distances based on patch location and resistance to movement of different land uses. We then used multistate capture-recapture modelling to quantify how survival and movement of this freshwater turtle were related to different metrics of landscape connectivity, in the wet and dry periods.
3. We captured 221 pond turtles, including 89 juveniles, 58 females, and 74 males. Survival was higher in ponds more connected with other ponds, especially for juvenile turtles. The probability of movement between ponds decreased with increasing least-cost distances. Movement probabilities tended to be higher in the dry than in the wet period.
4. Our results support the idea that landscape connectivity affects both movement and survival rates in a patchy population inhabiting a temporary pond network. These effects are likely to be particularly marked in unstable freshwater systems like ours, where individuals may have to move widely to escape drying ponds during particularly dry years.
5. Overall, our findings suggest that focusing conservation efforts solely on protecting discrete freshwater habitats such as temporary ponds may be insufficient, requiring also due consideration of landscape connectivity offered by the surrounding agricultural matrix to assure long-term persistence of patchy populations inhabiting such habitats.

     

Atmospheric culturable bacteria associated with meteorological conditions at a summer-time site in the mid-Willamette Valley,Oregon

A set of simultaneously collected quantitative measurements of 12 meteorological and 6 culturable atmospheric bacterial (CAB) variables was made over a grass seed field during several early, mid, and late summer days. The observation site was located between the Cascade and Coastal Mountain Ranges near Corvallis in the Willamette Valley, Oregon. Principal component analysis identified those meteorological variables that had the highest loadings in six eigenvectors that account for 95.9% of variation in the data factors, i.e., temperature @ 6.3 m above ground level (AGL), wind velocity @ 10.0 m AGL, wind velocity difference @ 1.7–10.0 m, barometric pressure, wind direction standard deviation, and wind direction. When these variables were used in a cluster analysis, they formed three statistically distinct meteorological variable clusters with means at ca. “midnight”, ca. “midday”, and ca. “evening.” The highest mean density of CAB (i.e., 153.4 ± 162.5 CFU/m³) was associated with the “midday” meteorological Cluster-1 that had warm, dry “gentle breezes” from the southeast, in the relatively bacteria loaded Willamette Valley air. The lowest mean density of CAB (i.e., 35.5 ± 24.1 CFU/m³) was associated with meteorological Cluster-3 in the late afternoon and “evening” occurring during the hottest and driest part of the day with “fresh breezes” coming from the north northwest in air off the Pacific Ocean. Finally, the last cluster, Cluster-2 occurred about midnight and had an intermediate density of CAB (74.2 ± 76.2 CFU/m³) in “light air” coming from the northwest, perhaps off the Pacific Ocean. The CAB associated with each of the three meteorological clusters was only partially statistically distinct. Partially because the CAB in both the Pacific Ocean derived air masses of the “evening” Cluster-3 and “midnight” Cluster-2 were not statically separable, though both were statistically separable from the midday, Willamette Valley derived Cluster-1. Further indicating their common source, both Pacific Ocean derived air masses had very similar percentages of pigmented bacteria, which were dissimilar to the pigmented bacterial population density in the Willamette Valley air masses. In short, it is speculated that “midnight” atmosphere may simply contain the settling concentrated residual bacterial particles in the abated fresh Pacific Ocean breezes after sundown. It is clearly shown that with the methods employed, it is possible to associate the uniqueness of the quantity, and to a lesser extent the quality, of the CAB population with the atmospheric conditions reported herein. From this project comes speculation that the strategies relating the quasi-conservative bacterial populations associated with distinct but nonconservative air mass properties can help to better understand more of the bacterial dynamics found in such situations. And to a further extent, molecular biological methods could be applied to identify bacterial taxa in specific air masses.     

Community effects following the deletion of a habitat-forming alga from rocky marine shores

Habitat-forming species increase spatial complexity and alter local environmental conditions, often facilitating a diversified assemblage of plants and animals. Removal of dominant species, therefore, can potentially lead to pronounced changes in diversity and community structure through a series of negative and positive interactions involving several components of the community. Here we test community responses to the deletion of the dominant, canopy-forming alga Hormosira banksii from the mid-intertidal zone of wave-protected rocky shores in southern New Zealand. This species was removed in winter (July) from three 3×3-m areas at each of two platforms (Kaikoura and Moeraki) on the east coast of the South Island. Initially, 59 taxa occurred in stands, but there were only four algal species with greater than 5% cover and three mobile invertebrate species with more than five individuals per 0.25 m². By 6 months after Hormosira removal, most fucoid and coralline algae had burned off, and there were blooms of ephemeral algae in the removal plots, but almost no change within controls. After 2 years, diversity declined by 44% relative to controls at Kaikoura and 36% at Moeraki, and the amount of bare space had increased by tenfold at Kaikoura and twofold at Moeraki. Few sessile or mobile invertebrates were present. Recruitment of Hormosira occurred after 14 months in the removal plots. At this time, a “press” disturbance was initiated into one half of each removal plot to test the effects of continued removal of Hormosira on diversity. Similar “end-points” of the control and “press” removal plots were not reached after 2 years, and even after Hormosira recruitment into the original “pulse” experiment there was little recovery of the community. In this mid-intertidal system with considerable thermal stress, and perhaps in others with few perennial species, diversity and community structure can critically depend on positive associations with a single dominant species.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.