Imprint of monsoonal patterns on the fish assemblage in coastal waters of south‐east India: a case study

The composition, species richness and diversity of a coastal fish assemblage from the Kalpakkam coast of south‐east India are described along with temporal distribution patterns related to seasonal fluctuations in dissolved oxygen, salinity, pH, chlorophyll‐a, phytoplankton and zooplankton species richness and density. A total of 244 fish species belonging to 21 orders, 87 families and 163 genera were recorded. The fish assemblage was dominated by reef‐associated species, followed by demersal species. The majority of the species (63%) are widely distributed in the western Indo‐Pacific as well as in the central Indo‐Pacific. Jaccard's coefficient analysis showed three distinct seasonal patterns of fish occurrence: pre‐monsoon (PrM), monsoon (M) and post‐monsoon (PoM). The maximum number of species was during the PrM period, followed by the PoM and M periods. Species occurrence analysis showed Sardinella longiceps to be dominant during PrM and M periods, Leiognathus dussumieri during the M period and Secutor insidiator and Secutor ruconius during the M and PoM periods. Canonical correspondence analysis indicated that salinity and rainfall were the two most influential environmental factors strongly correlated with temporal variation in the fish assemblage. The physico‐chemical conditions, in combination with factors such as greater food availability and shelter, might control the seasonal local distribution of the ichthyofauna in these Indian coastal waters.     

Factor Analysis of the Impact of the Environment on Microbial Communities in the Tvärminne Area, Southern Coast of Finland

Data already examined by regression analysis were subjected to factor analysis to scrutinize the effects of environmental factors on microbial populations in the brackish waters of the Tvärminne archipelago on the southern coast of Finland. Water samples were collected from 1.0-m depth at one point in Tvärminne Storfjärd, 71 times over about 2 years. Twenty-six parameters were determined on each sample, 10 of environmental and 16 of microbiological type. The correlations between the parameters were factorized using the principal axis solution, and eight factors chosen for further consideration were rotated by the varimax method. The major part of the variance (about 90% of the total communality) of the microbiological parameters was covered by five factors, interpreted as phytoplankton blooms, the periods before and after the blooms, freshwater outflows, and water temperature. Wind variables were components in the factors interpreted as freshwater outflows. Rainfall played a minor part in the total variance of the microbial community, but it washed yeasts and proteolytic bacteria from the land into the study area. The eight factors selected covered about 60 to 98% of the variance of the microbiological parameters. The highest values (above 90%) were obtained for direct counts of bacteria, for plate counts of mesophilic and polymyxin-resistant bacteria, and for the two community respiration parameters; the lowest values (60 to 75%) were obtained for H₂S-producing and proteolytic bacteria.     

Factor analysis of the impact of the environment on microbial communities in the tvärminne area, southern coast of Finland

Data already examined by regression analysis were subjected to factor analysis to scrutinize the effects of environmental factors on microbial populations in the brackish waters of the Tv?rminne archipelago on the southern coast of Finland. Water samples were collected from 1.0-m depth at one point in Tv?rminne Storfj?rd, 71 times over about 2 years. Twenty-six parameters were determined on each sample, 10 of environmental and 16 of microbiological type. The correlations between the parameters were factorized using the principal axis solution, and eight factors chosen for further consideration were rotated by the varimax method. The major part of the variance (about 90% of the total communality) of the microbiological parameters was covered by five factors, interpreted as phytoplankton blooms, the periods before and after the blooms, freshwater outflows, and water temperature. Wind variables were components in the factors interpreted as freshwater outflows. Rainfall played a minor part in the total variance of the microbial community, but it washed yeasts and proteolytic bacteria from the land into the study area. The eight factors selected covered about 60 to 98% of the variance of the microbiological parameters. The highest values (above 90%) were obtained for direct counts of bacteria, for plate counts of mesophilic and polymyxin-resistant bacteria, and for the two community respiration parameters; the lowest values (60 to 75%) were obtained for H(2)S-producing and proteolytic bacteria.     

Seasonal seawater temperature as the major determinant for populations of culturable bacteria in the sediments of an intact mangrove in an arid region

Mangroves are highly productive marine ecosystems where bacteria (culturable and non-culturable) actively participate in biomineralization of organic matter and biotransformation of minerals. This study explores spatial and seasonal fluctuations of culturable heterotrophic bacteria and Vibrio spp. in the sediments of an intact mangrove ecosystem and determines the dominant environmental factors that govern these fluctuations. Sediment samples were collected monthly from three stations in the mangroves of Laguna de Balandra, Baja California Sur, Mexico, through an annual cycle. Physicochemical parameters included seawater temperature, salinity, and concentration of dissolved oxygen. Viable counts of culturable heterotrophic bacteria and Vibrio spp. were made. In one sample (March 2003), nutrient concentrations (ammonium, nitrites, nitrates, and phosphates), organic matter, pH and sediment texture were also determined. General cluster analyses, analysis of variance of specific variables, and several principal component analyses demonstrated that seawater temperature is the principal determinant of seasonal distribution of culturable heterotrophic bacteria and Vibrio spp. in mangrove sediments. Soil texture, concentration of nutrients, and organic matter concentration contribute to heterogenicity to a lesser extent. A large spatial variation in bacterial populations was observed over short distances ( approximately 1 m) in sampling areas within the same site. These analyses show that the culturable bacterial distribution in sediments of mangroves has high spatial and temporal heterogeneity.     

Seasonal and spatial variability of soil respiration in four Sitka spruce stands

We investigated the causes for the seasonal and spatial variation of soil respiration in a first rotation Sitka spruce chronosequence composed of four age classes (10, 15, 31, and 47 year old) in Central Ireland. The study aimed at identifying easily determinable environmental parameters that explained the variation in soil respiration rates. The variation in temperature and soil water content influenced the seasonal trend observed in the spatial variability of soil respiration. The highest coefficients of variation in soil respiration were observed during autumn drought, while lower coefficients were generally observed during periods with highest soil respiration rates. On average, the sampling strategy of 30 sampling points per stand was adequate to obtain an average rate of soil respiration within 20% of its actual value at the 95% confidence level. Significantly higher soil respiration rates were observed at locations with high accumulation of organic matter and in collars established in close vicinity to tree stems. The organic layer thickness was the only variable that yielded significant regressions for explaining spatial variation in soil respiration in all the stands. Correlation analyses between the studied variables and soil respiration suggested the relative importance of heterotrophic and autotrophic components differed in their annual contribution to total soil respiration at each forest stand. Multiple regression analyses were used to assess the relative importance of primary temporal and spatial controls over soil respiration. Soil temperature and organic layer thickness explained most of the variance of soil respiration for the different sampling periods, while soil water content had a weaker effect as well as a different influence on soil respiration depending on the time of the year. The strong linear correlation between forest floor carbon and soil carbon stock further confirmed organic layer thickness as an integrative factor encompassing the effect of soil carbon pools on soil respiration. Moreover, its inclusion in the multiple regression analyses overrode the influence of both distance and fine root biomass. Overall, a multiple linear regression model driven by easily determinable environmental variables such as soil temperature, organic thickness, soil water content, soil bulk density, and soil organic carbon concentration allowed us to explain 54% of total variance of soil respiration over the different stand ages for the entire year (P < 0.05). Our results show that the adoption of an adequate sampling strategy, and the determination of some key environmental variables may help to explain a large proportion of total variation of soil respiration over the entire rotation length of afforested ecosystems.     

云南六库桔小实蝇成虫种群数量变动及其影响因子分析

应用诱蝇谜引诱剂诱捕法于2003-2005年调查了云南六库桔小实蝇成虫种群动态,系统分析了气候因子及寄主植物对该种群变动的影响。研究结果表明：云南六库桔小实蝇种群发生呈季节性,仅出现于3-12月,成虫消长基本为单峰型,高峰出现在7月。六库桔小实蝇种群数量与气温、降雨量和月雨日数等气象因子有密切关系。决定系数和通径分析结果显示,月降雨量是影响六库桔小实蝇种群动态的主要决策因素;月平均气温和月平均最低气温是影响种群数量变动的主要限制因素,其中,月平均最低温度是间接影响种群数量变动的重要指标。主成分分析筛选出低温条件主成分,其累积方差贡献率达77.65%。逐步回归分析也证实,影响六库桔小实蝇种群月变动的主要气象因子是月平均气温和月平均最低气温。综合分析认为,低温是导致六库桔小实蝇季节性发生的关键因素。     

Assessing cockle shells (Anadara granosa) for reconstruction subdaily environmental parameters: Implication for paleoclimate studies

This study aims to investigate the potential of cockle shells as an environmental recorder, examining the environmental factors controlling the shell growth of the intertidal Anadara granosa from west coast of Malaysia. Subdaily environmental factors were recorded from December 2011 to November 2012. A total of 600 individuals were collected on a monthly basis and the shells sectioned from umbo to ventral margin, polished, etched and photographed under a light microscope to observe microgrowth bands and increments. Comparison of correlation matrix between mean increment width and each environmental factor indicated that shell growth had the highest positive correlation with seawater temperature (+0.72) and weak positive correlation with salinity (+0.53). Multiple regression analysis was used to assess independent associations between shell mean increment width and environmental parameters. Study model showed that 60.8% of the variation in shell growth could be explained by temperature, salinity, rainfall and tidal change. Individually, temperature and salinity made the greatest unique contribution to explain shell growth, respectively (p < 0.01). Laboratory results showed shell growth was in a linear trend to optimum temperature and salinity. These findings provide a basis for the interpretation of the temporal changes in shell microgrowth patterns in terms of environmental conditions of cockle shells.     

Life-History Variation in Caribbean gambusia, Gambusia puncticulata puncticulata (Poeciliidae) from the Cayman Islands, British West Indies

We studied seasonal and spatial variability in the reproductive life-history traits of Caribbean gambusia, Gambusia puncticulata puncticulata, using collections representing dry and wet periods from eight pond sites located across the three Cayman Islands. Caribbean gambusia exhibited a seasonal life-history response over the 5-month interval between the relatively dry and wet periods, marked by shifts to larger adult sizes and smaller broods made up of larger offspring. This seasonal shift in the life-history pattern coincided with increased rainfall, lower salinity, lower water temperature, and higher food availability. Overall, there was a reproductive trade-off involving a reciprocal relationship between brood size and mean embryo mass, and a direct relationship between brood size and total embryo mass. Levels of various environmental variables, including salinity, submerged aquatic vegetation cover, and capture depth, were apparently unrelated to the life-history pattern. Furthermore, the life-history pattern did not reflect an island effect. However, a correlation between the seasonal difference in salinity and offspring size suggested that the Cayman Island life-history pattern may correspond in part with the environmental stability hypothesis.     

Aquaculture planning for suspended bivalve farming systems: The integration of physiological response of green mussel with environmental variability in site selection

Bivalve Condition Index (CI) is widely employed in environmental monitoring programmes as it integrates physiological responses to stress with changes in somatic growth. Besides indicating, the commercial quality of a bivalve population it may be also be used to compare the relative health of animals in nearby populations. In this study, CI of green mussels, Perna viridis was evaluated as the intrinsic response to the variations in the environment in two potential mussel mariculture sites in the tropical monsoon region with diverse remoteness to riverine outflow. Condition index of mussels from site with relatively higher riverine influence (RI) was compared with mussels from area of reduced riverine (RR) influence along Karnataka coast (Eastern Arabian Sea). The dominant patterns of spatial trends in 12 environmental variables (temperature, salinity, pH, dissolved oxygen, rainfall, chlorophyll-a (chl-a), suspended particulate matter (SPM) particulate organic matter (POM), particulate inorganic matter (PIM), POM/SPM, chla/POM and PIM%) of the sites were resolved by Principal Component Analysis (PCA). The stepwise multiple regression analysis related the spatial variability in CI to variations in water temperature and organic content of the seston (chlorophyll-a and particulate organic matter). The discriminant analysis performed with monthly mean water temperature, chl-a levels and CI ratio [high CI ratio (CI_high) and low CI ratio (CI_low)] indicated that 83.9% of the CI_high was associated with high chl-a and high water temperature group whereas, 72.4% of CI_low were associated with low chl-a and low water temperature regime. The RR site presented less variation in environmental parameters offering a more conducive environment for the growth of mussels, characterised by better CI with low seasonal variations. Whereas, in the site proximate to riverine discharge, reserves were alternatively channelled into energy-consuming processes and hence unfavourable environmental conditions showed poor tissue condition due to utilization of energy reserves which were potentially destined for growth. Thus, average CI, besides its representation of the general health condition of the bivalves can potentially be used in selecting suitable sites for bivalve mariculture in comparable hydrological environment.     

Leaffall Phenology in a Subtropical Wet Forest in Puerto Rico: From Species to Community Patterns

Leaffall phenology is an important periodical event in forests, contributing to mobilization of organic matter from primary producers to soil. For seasonal forests, leaffall periodicity has been related to rainfall regime and dry season length. In weakly seasonal forests, where there is no marked dry season, other climatic factors could trigger leaf shed. In this study, we aimed to determine if other climatic variables (wind speed, solar radiation, photosynthetic photon flux density [PPFD], day length, temperature, and relative humidity) could be better correlated with patterns of litter and leaffall in a weakly seasonal subtropical wet forest in Puerto Rico. Leaffall patterns were correlated mainly with solar radiation, PPFD, day length, and temperature; and secondarily with rainfall. Two main peaks of leaffall were observed: April–June and August–September, coinciding with the periods of major solar radiation at this latitude. Community leaffall patterns were the result of overlapping peaks of individual species. Of the 32 species analyzed, 21 showed phenological patterns, either unimodal (16 species), bimodal (three species), or multimodal (two species). Lianas also presented leaffall seasonality, suggesting that they are subject to the same constraints and triggering factors affecting trees. In addition to solar radiation as a main determinant of leaffall timing in tropical forests, our findings highlight the importance of interannual variation and asynchrony, suggesting that leaffall is the result of a complex interaction between environmental and physiological factors.     

Environmental variables and their interaction effects on chlorophyll-a in coastal waters of the southern Caspian Sea: assessment by multiple regression grey models

Main and interaction effects of environmental parameters on variations of chlorophyll-a along the coast of the southern Caspian Sea were determined. Parameters such as temperature, conductivity, turbidity salinity, dissolved oxygen (DO), pH, chlorophyll-a and nutrients were evaluated monthly in four transects and different depths (0, 5, 10, 20, 35 and 50 m), using multiple regression and grey relational analysis. Additionally, the long-term data (1994–2009) on the seasonal phytoplanktonic variation were included in our discussion. There was a good agreement between the observed and predicted values in the models that included the interaction effects during spring, summer, autumn and winter, with the adjusted R ² of 0.64, 0.63, 0.60 and 0.54, respectively. Temperature and its interactions were found to be the most important factor on chlorophyll-a throughout the year. Overall, the most effective factors were seasonally categorized as: organic phosphorus, ammonium and their interactions (spring); organic phosphorus, nitrate, DO, silica and their interactions (summer); organic phosphorus, pH, DO and their interactions (autumn); pH, ammonium, DO and their interactions (winter). Thermocline, riverine transport, nitrification and the presence of Mnemiopsis leidyi and Cyanophyta were found to be the most important phenomena affecting the dynamics of nutrients and phytoplanktonic biomass in the area. In the distribution of chlorophyll-a, the interaction effects of different environmental parameters proved to be more important than their individual effects. The multiple regression and grey analyses were also found to be useful tools to understand the interactions between phytoplankton and environmental factors.     

Factors associated with the prevalence of Perkinsus marinus in Crassostrea virginica from the southern Gulf of Mexico

The protozoan Perkinsus marinus is considered the most important pathogen of the eastern oyster Crassostrea virginica, causing high mortality in natural and farmed oysters on the Atlantic coast of the US. In Mexico, no serious P. marinus epizootic has been reported. This study describes the current state of P. marinus prevalence in Terminos Lagoon (Mexico) associated with environmental factors including salinity, temperature, ammonium, nitrate, nitrite, silica, and phosphorus. In addition, the association of physiological (hemocyte density, protein concentration) and immunological (lysozyme, agglutination) parameters with the infection were studied. The prevalence was significantly different among seasons with mean values of 70, 23, and 7% in the dry (February to May), rainy (June to September) and north-wind (October to January) seasons, respectively. Only light infection intensity (Mackin scale value < 1) was observed. Prevalence of P. marinus was associated with seasonal salinity, phosphorus, and silica variations. Comparisons of oyster health demonstrates that the rainy and north-wind seasons are stressful periods. Redundancy analysis showed that only 34% of the variation in seasonal P. marinus prevalence was explained by protein concentration (21%), lysozyme (12%), and agglutination (1%). Overall, the data suggest that freshwater input associated with high nutrient concentrations during the rainy and north-wind seasons has a strong negative effect on P. marinus prevalence and also influences the oysters' physiology. It is probable that this seasonal stress was responsible for the absence of an epizootic event in Terminos Lagoon.     

Flux of organic carbon in a riverine mangrove wetland in the Florida Coastal Everglades

Short-term (daily) and seasonal variations in concentration and flux of dissolved organic carbon (DOC) were examined over 15 tidal cycles in a riverine mangrove wetland along Shark River, Florida in 2003. Due to the influence of seasonal rainfall and wind patterns on Shark River’s hydrology, samplings were made to include wet, dry and transitional (Norte) seasons. We used a flume extending from a tidal creek to a basin forest to measure vertical (vegetated soil/water column) and horizontal (mangrove forest/tidal creek) flux of DOC. We found significant (p < 0.05) variations in surface water temperature, salinity, conductivity, pH and mean concentration of DOC with season. Water temperature and salinity followed seasonal patterns of air temperature and rainfall, while mean DOC concentration was highest during the dry season (May), followed by the wet (October) and ‘Norte’ (December) seasons. This pattern of DOC concentration may be due to a combination of litter production and inundation pattern of the wetland. In contrast to daily (between tides) variation in DOC flux between the mangrove forest and tidal creek, daily variations of mean water quality were not significant. However, within-tide variation of DOC flux, dissolved oxygen content and salinity was observed. This indicated that the length of inundation and water source (freshwater vs. saltwater) variation across tidal cycles influenced water quality and DOC flux in the water column. Net DOC export was measured in October and December, suggesting the mangrove forest was a source of DOC to the adjacent tidal creek during these periods. Net annual export of DOC from the fringe mangrove to both the tidal creek and basin mangrove forest was 56 g C m⁻² year⁻¹. The seasonal pattern in our flux results indicates that DOC flux from this mangrove forest may be governed by both freshwater discharge and tidal range.     

Space and time distribution of zooplankton in a Mediterranean lagoon (Etang de Berre)

In the Berre lagoon, a large brackish and swallow area near Marseille, the environmental factors (temperature, salinity, oxygen, suspended particulate matter and chlorophyll) generally display strong space and time variations. The rotifer Brachionus plicatilis and the copepod Acartia tonsa constitute the bulk of the zooplankton population during all the year. Their space and time distributions were studied in 23 stations distributed all over the lagoon, during four seasonal cruises (February, June, October, November), at surface and bottom layers. There is no marked difference in the horizontal and vertical distribution of the two species, (except in November when rotifers were prevailing in surface and copepods at depth) and in their time occurence. When the four series of data are pooled, correlation analysis show that A.tonsa is positively correlated with temperature, salinity and seston and negatively to oxygen and chlorophyll. B. plicatilis is positively correlated with temperature and seston, but also with chlorophyll, while salinity has a negative effect. The specific eggs number of both species is chlorophyll dependent. Considering seasonal cruises separately, some differences appear in the sense or the significance of these different correlations. The respective distribution of the two species is only partly dependent on the variation of the environmental factors: most of the variance remains unexplained, as indicated by the result of a stepwise multiple regression analysis using the most significant factors (temperature, salinity and oxygen explain 33 to 42% of the variance in Acartia, while temperature and salinity explain 27 to 28% of the variance in Brachionus). Thus, internal behavioral factors could also play a role in the distribution of organisms, particularly in some cases of aggregations of organisms observed during this study. As the two species occupied the same space habitat most of the year, they are potentially in competition for food. A way to optimize the food utilization could be the time separation of their feeding activity, nocturnal in Acartia and diurnal in Brachionus. Another way could be selective feeding upon food particles depending on their size (Brachionus being able to use finer particles than Acartia) or their quality (Brachionus being more herbivorous than Acartia) as demonstrated in some grazing experiments carried out in parallel.     

Climate and landscape correlates of African lion (Panthera leo) demography

Although many studies have documented aspects of lion ecology, they have generally focused on single sites, leaving broader-scaled factors unanalysed. We assessed range-wide effects of eight biotic and 26 abiotic variables on lion distribution and ecology, based on data compiled from published sources on lion population ecology in 27 protected areas in Africa. Lion pride size and composition were independent of lion density; lion density and home range size were inversely related; and lion density was positively related to rainfall, soil nutrients and annual mean temperature, with some interactive effects between rainfall and soil nutrients. Lion demography was associated most strongly with rainfall, temperature and landscape features. Herbivore biomass and lion density were correlated in univariate regression analyses. However, because herbivore biomass was also related to rainfall and temperature, hierarchical partitioning (HP) allowed us to evaluate independent effects of each variable on lion demography revealing that herbivore biomass had negligible independent contributions. HP indicated that climatic parameters explained 62% of overall variance in demographic parameters, whereas landscape features explained only 32%; climatic parameters were fairly balanced between effects of temperature (34%) and rainfall (28%). Prey (herbivore) biomass is important for lion survival, but its effects appear secondary to environmental factors.     

种植碱蓬和秸秆覆盖对沿海滩涂极重度盐土盐分动态与脱盐效果的影响

为探明沿海滩涂极重度盐土盐分动态规律及其影响因子,并探讨盐生植被和秸秆覆盖下土壤的脱盐及控盐效果,2014年5月—2015年5月,在江苏沿海滩涂极重度盐土中进行田间试验,设置4种处理:对照(裸地,CK)、种植碱蓬(PS)、15 t·hm^-2秸秆覆盖(SM-A)和30t·hm^-2秸秆覆盖(SM-2A),监测气候因子和土壤盐分的动态变化.结果表明:(1)滩涂裸地表层土壤盐分具有显著的季节性变化特征,表现为在6—8月盐分降低至最低值(8.69g·kg^-1),9—12月呈现积盐作用,最大值为26.66 g·kg^-1;表层土壤盐分变化比亚表层更剧烈,而且亚表层盐分变化相对于表层具有一定的滞后性;(2)相关分析表明,滩涂裸地表层盐分变化与采样前15 d的累积降雨量及蒸降比具有显著的线性关系;多因子及互作逐步分析表明,降雨量增加可以显著促进脱盐作用,大气温度升高可加剧盐分积累,降雨量和大气温度的互作效应增加会对盐分累积产生正效应;(3)PS处理没有显著改变土壤盐分的季节性变化规律,但降低了表层土壤盐分;(4)SM-A和SM-2A条件下,土壤脱盐率与覆盖处理天数回归拟合符合Logistic曲线,且经过雨季覆盖处理90~100 d后表层土壤脱盐率均可达到95.0%以上,覆盖处理120 d后亚表层土壤脱盐率均可达到92.0%以上,之后表层和亚表层土壤盐分分别在0.60和1.00 g·kg^-1以下波动.综合考虑脱盐效果和经济投入,在梅雨季节前(4—5月)采用15 t·hm^-2秸秆覆盖,可能是未来滩涂极重度盐土进行快速脱盐和改良的重要措施.     

A geometric morphometric approach to the study of ecogeographical and clinal variation in vervet monkeys

Aim To examine and visualize clines in size and shape of Cercopithecus aethiops Linneus, 1758 (Primate, Cercopithecidae) skulls, and to investigate environmental factors which might best explain the observed variation. Location Sub‐Saharan Africa. Methods Eighty‐six three‐dimensional anatomical landmarks were used to describe 306 skulls of adult C. aethiops sampled over its entire distribution. Geometric morphometric methods for the quantitative analysis of form variation were applied. Size and shape variables were computed and regressed onto geographical coordinates and environmental variables (elevation, temperature, rainfall, moisture and Shannon rainfall diversity index) using both linear and curvilinear models. Components (geographical, environmental, spatially structured environmental and residual) of ecogeographical variation in skull form were partitioned using partial regression. A novel approach for summarizing and visualizing nonlinear patterns of clinal variation using surface rendering of three‐dimensional shapes is presented. Results Clinal variation in size and shape was highly significant, and was best described by curvilinear models. There were strong similarities between females and males. The cline in size was especially pronounced, explaining up to about 40% of observed variation, and was mainly longitudinal rather than latitudinal. A major trend of clinal shape variation also occurred from west to east, and corresponded to an expansion of the face relative to the neurocranium in the west. In the east, skulls also tended to be deeper and with narrower zygomatic arches. Geography and the spatially structured environmental component were the major contributors to the explained variance in size in both sexes, but the proportion of variance explained by the latter was smaller in females. In contrast, geography and environment explained similar amounts of variation in shape and their contribution was about twice that of the spatially structured environmental component. About 60–80% of variation in skull form was not explained by any variable in the analysis. The main factors influencing skull size differed in females and males, with rainfall being very influential in males. Both female and male skull shapes were strongly affected by average annual rainfall. Main conclusions A strong spatial and environmental basis to variations in African vervet monkey skull form was evident. However, the observed pattern did not conform to predictions based on Bergmann's rule. Rainfall consistently emerged as an important predictor, which may contribute to intraspecific variation in the size and shape of vervet monkey skulls through its effect on habitat productivity.     

Periodicity and environmental drivers of apical and lateral growth in a Cerrado woody species

Key message

Apical and lateral growth are seasonal in a Cerrado species, and these events are related to each other and linked with climatic and environmental features.

Abstract

In the Cerrado, a tropical ecosystem with seasonal rainfall, we investigated the timing of leaf production and cambial activity, and checked whether these features are related to each other and with climatic and environmental factors. Between September 2011 and December 2012, sampling of main stem and vegetative phenological observations of Kielmeyera grandiflora (Wawra) Saddi (Calophyllaceae) were done monthly to assess seasonality in leaf production and cambial activity, and to compare these features with each other. To check the relationship of bud opening and the onset of cambial activity with climatic and environmental features, the average temperature and day length, and the precipitation sum in a time window ranging from 1 to 30 days before the occurrence of these events were recorded, and the coefficient of variation was calculated. Leaf production and cambial activity were seasonal. Bud opening occurred in September 2011 and August 2012, during the dry season. The onset of cambial activity occurred in October both in 2011 and 2012, 1–2 months after bud opening, at the beginning of the rainy season. The cambium was dormant in May, during the rainy season. Photoperiod and temperature showed low coefficients of variation in the time window before bud opening and onset of cambial activity, while rainfall presented a high coefficient of variation. Thus, both apical and lateral growth are seasonal events in Cerrado species, and are related to each other. A set of climatic and environmental features is related with seasonal growth, among which photoperiod and temperature may be important in the regulation of these events.

     

Planktonic Luminous Bacteria of Vellar Estuary,South India

Distribution of planktonic luminous bacteria in relation to environmental parameters was investigated at two stations located in the Vellar Estuary. Luminous microflora showed a pronounced seasonal cycle with very low counts during monsoon months followed by an increase in post monsoon and peak counts during summer. The population density of these procaryotes was remarkably high ranging from 3.5 to 33.1 colony forming units per ml. They constituted 2.1 to 52.1 % of the total bacterial counts. Salinity appeared to govern the distribution of luminous procaryotes as their counts corresponded well with fluctuations in salinity. Taxonomic affiliation of the isolates revealed predominance of Vibrio harveyi. Vibrio fischeri and Photobacterium leiognathi exhibited sparse distribution.     

Critical Factors Influencing the Occurrence of Vibrio cholerae in the Environment of Bangladesh

The occurrence of outbreaks of cholera in Africa in 1970 and in Latin America in 1991, mainly in coastal communities, and the appearance of the new serotype Vibrio cholerae O139 in India and subsequently in Bangladesh have stimulated efforts to understand environmental factors influencing the growth and geographic distribution of epidemic Vibrio cholerae serotypes. Because of the severity of recent epidemics, cholera is now being considered by some infectious disease investigators as a “reemerging” disease, prompting new work on the ecology of vibrios. Epidemiological and ecological surveillance for cholera has been under way in four rural, geographically separated locations in Bangladesh for the past 4 years, during which both clinical and environmental samples were collected at biweekly intervals. The clinical epidemiology portion of the research has been published (Sack et al., J. Infect. Dis. 187:96-101, 2003). The results of environmental sampling and analysis of the environmental and clinical data have revealed significant correlations of water temperature, water depth, rainfall, conductivity, and copepod counts with the occurrence of cholera toxin-producing bacteria (presumably V. cholerae). The lag periods between increases or decreases in units of factors, such as temperature and salinity, and occurrence of cholera correlate with biological parameters, e.g., plankton population blooms. The new information on the ecology of V. cholerae is proving useful in developing environmental models for the prediction of cholera epidemics.