Geographical and typological changes in fish guilds of South African estuaries

A comparative analysis of fish estuary association guilds was undertaken on some 190 South African estuaries. This pioneering study spanned three zoogeographic regions and included three broad estuarine types. The guild compositions of the estuaries were compared based on an importance value, incorporating taxonomic composition, numerical abundance and relative biomass. Multivariate analyses included both inter‐regional (zoogeographic) and intra‐regional (estuarine typology) comparisons. The major estuary‐associated guilds (estuarine species and marine migrant species) were important in all estuary types within all biogeographic regions. Significant differences both between regions and between estuary types within regions, however, were recorded. Cool–temperate estuaries were generally dominated by migratory species (estuarine migrants and marine migrant opportunists) while the importance of species dependent on estuaries (estuarine residents and estuarine‐dependent marine migrants) was higher in warm–temperate and subtropical regions. The significance of estuarine nursery areas, particularly in regions where estuaries are few in number, is highlighted. In terms of typology, migratory species assumed a greater importance in predominantly open systems, while freshwater and estuarine‐resident species were more important in predominantly closed systems. Predominantly closed estuaries, however, were also important for marine migrant species, which further highlights the significance of these systems as nursery areas for fishes.     

Development of a Fish Based Lake Typology for Natural Austrian Lakes >50 ha Based on the Reconstructed Historical Fish Communities

Based on the reconstructed native fish communities all natural Austrian lakes >50 ha (n = 43) were classified into four groups using cluster analysis methods. Sentinel species (i.e. species with highest discriminating value for lake types and characteristic for a specific lake group) and type specific fish species (accompanying species with additional value for characterising lake groups) were defined by a newly developed index and by similarity analysis. The first group included 16 lakes of high altitude, small surface area and low fish species number with arctic char as a sentinel species. The second group (n = 10) was characterized by intermediate altitude, large surface area and high maximum water depth with the minnow as sentinel species. The third group contained 14 lakes with low maximum water depths and a long retention time. For this group the bleak was found as a sentinel species. The lakes of the eastern part of Austria represented the last group (n = 3) and were characterized by low altitude and very shallow water depth with pike‐perch as a sentinel species. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fish trophic structure in estuaries,with particular emphasis on estuarine typology and zoogeography

A comparative analysis of the fish trophic structure was undertaken on some 190 South African estuaries spanning three zoogeographic regions and incorporating three broad estuarine types. Fish biomass trophic guild compositions and biomass trophic spectrum profiles were analysed using multivariate statistical techniques and included both inter‐regional (zoogeographic) and intra‐regional (estuarine typology) comparisons. Differences in the fish trophic structure of the various estuary types within each zoogeographic region were observed; these were linked to the relative biomass contribution of the various trophic guilds and also to differences in biomass trophic spectrum profiles of the fishes in each estuary type within each region. In spite of these differences in trophic structure, all estuaries were dominated by detritivores, which suggests that the main food source (detritus) is similar in all biogeographic regions. Preliminary indications are that a similar dependence by estuary‐associated fishes on detritus food sources exists on a global basis but that detailed studies are required in order to confirm this assertion.     

Forest structure and biomass of mangroves in the Mgeni estuary,South Africa

Forest structure and biomass were determined in a mangrove stand dominated by Bruguiera gymnorrhiza (L.) Lam. Trees in 5 m² sample plots were harvested at ground level and then further cut into 1 m strata for separation into living wood, dead wood, leaves, reproductive material and pneumatophores. Mean above-ground living biomass was calculated at 94.49±7.83 t dry matter ha^–1, while dead wood contributed a mean mass of 7.63±0.89 t dry matter ha^–1. Excavations of roots yielded a below-ground biomass of 9.67 t dry matter ha^–1 which represented only 9.8% of the above-ground value. There was a mean density of 4700 living stems ha^–1 with plant heights ranging from 0.57 m to 5.80 m. Mean LAI was 4.95±0.80. As a basis for estimating standing biomass, regression lines were fitted to biomass values from individual trees of B. gymnorrhiza and Avicennia marina (Forssk.) Vierh. of various sizes. A comparison of these relationships with methods used by previous workers for estimating biomass suggests that most other methods cannot be applied without modification for local stands of mangroves.     

Fish Communities of the Lower Fraser River (Canada) and a 21-year Contrast

Fish communities were sampled at 14 sites along the lower 120km of the Fraser River, British Columbia by beach seine four times in 1972–1973 and three times in 1993–1994. Of the 37 species collected, peamouth chub, largescale sucker, starry flounder, and northern squawfish were predominant in either density or biomass. Densities and biomass of most species and all fish combined were higher in 1993–1994. Strong rank correlations of species abundance or biomass indicated that the overall fish community structure was very similar in both periods. At smaller spatial scales (reaches of 2–3 sites) and shorter time scales (by season), less than half the comparisons showed any significant correlation indicating changes in community composition. Largescale sucker, one of the largest contributors to biomass in both periods, showed decreased abundance, i.e., lower density, lower biomass, and large differences in the size-frequency distribution, specifically very low representation of small size classes. Other species, especially small-bodied forms, generally increased in numbers. Despite large changes in the lower Fraser River ecosystem in the past 21 years, the overall fish community has shown remarkably little change over that interval.     

Intraguild Predation and Interspecific Killing as Structuring Forces of Carnivoran Communities in South America

Intraguild predation (IGP) and interspecific killing (IK) have been recently acknowledged as important ecological forces that could influence community structure. Not only can carnivores influence prey community composition, they might also impact the populations of other carnivores. The goal of the current study was to assess the role of IGP and IK as significant forces influencing carnivoran assemblages in South America. To this end, we compiled the available records on 35 species of terrestrial carnivorans in the subcontinent, to investigate the potential and actual extent of IGP/IK as widespread ecological forces. We considered potential intraguild predators those having >20 % range overlap and body mass 2–5.4 times greater than that of other guild members and likely-potential intraguild predators those that, in addition, were also hypercarnivorous. The potential number of intraguild predators for those species evaluated ranged from zero to 18 (mean?=?5.35?±?SE 0.74). IGP/IK events (n?=?116) included 52 pairs of Neotropical carnivorans, 13 of which were killers and 25 were victims. Confirmed intraguild predator species (n?=?13) accounted for 37.1 % of the assemblage, nearly the same value predicted to be likely potential predators (n?=?14). IGP and IK were highly associated with the hypercarnivorous felids, whereas victim species were most often the omnivorous procyonids and skunks. The results indicate jaguars, pumas, and ocelots as the species most likely to have significant impact on the guild. IGP and IK are not random and reflect widespread interactions that influence carnivoran community structure in South America.     

Circadian Typology and Sensation Seeking in Adolescents

The relationship of circadian typology with personality has been largely studied in adults, but there are few studies exploring such relationship in adolescents. Adolescence has been associated with a greater tendency to eveningness preference, sleeping problems, poorer academic achievement, earlier substance use, or risky behaviors, and it is suggested that this association might be mediated by personality factors. Given the relevance of identifying the behavioral outcomes of young evening types to detect and prevent health problems, the present study aimed to explore, for the first time, the relationship between sensation seeking and circadian typology in an adolescent sample of 688 students (51.45% boys) from 12 to 16 yrs old. They answered the Spanish versions of the Morningness-Eveningness Scale for Children (MESC) and the Junior Sensation Seeking Scale (J-SSS), which includes four subscales measuring Thrill and Adventure Seeking, Experience Seeking, Disinhibition, and Boredom Susceptibility. Analyses showed that boys obtained significantly higher scores than girls on J-SSS total score and all subscales except Boredom Susceptibility, whereas evening-type adolescents of both sexes scored significantly higher than neither types and than morning types on J-SSS total score. These results indicate that evening-type adolescents show a greater desire for varied, new, complex, and intense sensations, and they are ready for experiencing more risks than morning types. The implications of this study suggest the need of being aware of individual differences in the SS trait in evening-type adolescents, as well as taking into account the wide variety of behaviors associated with it, either prosocial or antisocial, to design better preventive health and academic programs. (Author correspondence: anna.muro@uab.cat)     

Reviewing the Psychometric Properties of Contemporary Circadian Typology Measures

The accurate measurement of circadian typology (CT) is critical because the construct has implications for a number of health disorders. In this review, we focus on the evidence to support the reliability and validity of the more commonly used CT scales: the Morningness-Eveningness Questionnaire (MEQ), reduced Morningness-Eveningness Questionnaire (rMEQ), the Composite Scale of Morningness (CSM), and the Preferences Scale (PS). In addition, we also consider the Munich ChronoType Questionnaire (MCTQ). In terms of reliability, the MEQ, CSM, and PS consistently report high levels of reliability (>0.80), whereas the reliability of the rMEQ is satisfactory. The stability of these scales is sound at follow-up periods up to 13 mos. The MCTQ is not a scale; therefore, its reliability cannot be assessed. Although it is possible to determine the stability of the MCTQ, these data are yet to be reported. Validity must be given equal weight in assessing the measurement properties of CT instruments. Most commonly reported is convergent and construct validity. The MEQ, rMEQ, and CSM are highly correlated and this is to be expected, given that these scales share common items. The level of agreement between the MCTQ and the MEQ is satisfactory, but the correlation between these two constructs decreases in line with the number of “corrections” applied to the MCTQ. The interesting question is whether CT is best represented by a psychological preference for behavior or by using a biomarker such as sleep midpoint. Good-quality subjective and objective data suggest adequate construct validity for each of the CT instruments, but a major limitation of this literature is studies that assess the predictive validity of these instruments. We make a number of recommendations with the aim of advancing science. Future studies need to (1) focus on collecting data from representative samples that consider a number of environmental factors; (2) employ longitudinal designs to allow the predictive validity of CT measures to be assessed and preferably make use of objective data; (3) employ contemporary statistical approaches, including structural equation modeling and item-response models; and (4) provide better information concerning sample selection and a rationale for choosing cutoff points.     

Geographical affinities of the Cape flora, South Africa

Aim The flora characteristic of the Cape Floristic Region (CFR) is dominated by a relatively small number of clades that have been proposed as ‘Cape clades’. These clades have variously been suggested to have African or Austral affinities. Here we evaluate the support for these conflicting hypotheses. In addition, we test the hypothesis that these clades share a common time of differentiation from their geographical neighbours. Location The Cape Floristic Region, South Africa Methods We use both published and unpublished phylogenetic information to investigate the geographical sister areas of the Cape clades as well as the timing and the direction of biogeographical disjunctions. Results Almost half of the Cape clades for which unambiguous sister areas could be established show a trans‐Indian Ocean disjunction. The earliest trans‐Indian Ocean disjunction dates from 80 Ma. Other disjunctions date from various times in the Cenozoic, and we suggest that the process of recruiting lineages into the Cape flora might be ongoing. Relatively few Cape clades show a sister relationship with South America and tropical Africa, despite their relative geographical proximity. Numerous Cape clades contain species also found on tropical African mountains; in all cases tested, these species are shown to be embedded within the Cape clades. While many Cape clades show a relationship with the Eurasian temperate flora, this is complicated by their presence in tropical Africa. The single case study addressing this to date suggests that the Cape clade is nested within a European grade. Main conclusions Although many Cape clades show Austral rather than African relationships, there are numerous other patterns suggestive of a cosmopolitan flora. This spatial variation is echoed in the temporal data, from which, although there is wide variance around the dates of disjunctions, it is clear the Cape flora has been assembled over a long time period. There is no simple hypothesis that can account for the geographical sources of the currently distinctive Cape flora. The phylogenetic positions of Afromontane members of Cape clades suggest a history of dispersal from the CFR, rather than the reverse.     

Biogeography and species richness of endophagous insects associated with Proteaceae in South Africa

The endophagous insects associated with Proteaceae of the Cape fynbos were compared to endophage assemblages from more northern non-Capensis Proteaceae. Insects were collected from Proteaceae in the Cape on a regular basis and additional records obtained from insect collections. Northern samples were collected more opportunistically or records were obtained from collections or through personal communication. The Cape fynbos genus Protea is utilized by many more insect taxa than the non-fynbos Protea species. The fynbos Proteaceae has very few species in common with the northern Proteaceae, yet each has many of their own distinct species. This suggests that the fynbos endophage insect fauna is distinct from that of the other regions. It appears that the high diversity of host plants in the fynbos has contributed to generating high, local endophagous insect diversity.     

The distribution and biology of nomadic birds in the Karoo, South Africa

Dryland nomadic bird species, as a proportion of all bird species in a biome in southern Africa, are highest in the arid grassland and arid and semi-arid Karoo in South Africa. Nomadic birds, of which the most widespread species is the greybacked finchlark Eremopterix verticalis (Smith), are most frequently observed in the north-central and north western Nama Karoo. The species richness of nomadic species is inversely correlated with species richness of all bird species in the Karoo. Since the distribution of nomadic birds is in areas where rainfall is patchy, low (<250 mm per year) and aseasonal, this supports the idea that fewer species are able to cope with resources that are patchy in time and space, and that there has been selection for nomadism in the species that are able to use patchy environments. Species richness and abundance of nomadic birds is negatively correlated with rainfall amount but positively correlated with the coefficient of variation of the rainfall and with rainfall in autumn. The frequency of nomadic birds is inversely correlated with altitude range; nomadic species are most often recorded in structurally simple habitats (shrubland and grassland) on open plains. Most nomadic bird species in the Karoo are granivorous. Perennial desert grasses are important components of the habitat and diet of small nomadic granivores, and also provide nest sites and nest material. Nomadic birds can breed throughout the year, without a clearly defined ‘season’ in both the Succulent and Nama Karoo. Average clutch sizes do not differ significantly between resident and all nomadic species in the arid and semi-arid Karoo. Nomadism is an evolutionary stable strategy for individual species only when extremes in environmental conditions are frequent enough, and unpredictable enough, to maintain movements to high resource patches or to maintain dispersal away from low resource patches. If high rainfall years are too regular or infrequent, or peaks in fluctuations of resources in the environment too low, or rainfall patches are randomly distributed, nomadism would not be maintained as part of the individual behaviour pattern.     

Biodegradation of Dichloromethane in an Estuarine Environment

Dichloromethane (DCM) is a toxic pollutant showing prolonged persistence in water. So far, biodegradation of DCM has only been reported in soils and freshwater systems. Herein, we studied whether or not biodegradation of DCM could occur in estuarine waters. Results showed over 90% mineralization of DCM in natural estuarine waters supplemented with DCM. Biodegradation of DCM in estuarine waters occurred by association of different bacterial species. Generally, two bacterial species participated in DCM degradation. Two bacterial consortia were obtained. Consortia were able to degrade around 80% of DCM in about 6 days. The species involved in the process were identified by 16S rRNA gene sequencing; a consortium was constituted by Pseudomonas sp. and Brevundimonas sp. and a second consortium was formed by Pseudomonas sp. and an Acinetobacter sp. Our results showed that DCM can be readily biodegraded in estuarine waters.     

River Dan,headwater of the Jordan,an aquatic oasis of the Middle East

River Dan is the largest of the headwater rivers of the Jordan. The karstic exsurgence of the Dan has a seasonally stable output, a long stretch of strongly turbulent flow, stable temperature around 15.5°C and high oxygen saturation. A total of 156 taxa, mainly at the species level, were identified from the river. These species are almost exclusively of Palearctic origin. About half of the species are limited to the northernmost part of Israel. The faunal complex described, does not present any longitudinal zonation for the 5 kilometers of turbulent flow; neither does it present seasonal changes in species composition. River Dan is considered to be a post-Pleistocenic river which has an important function of refugium for a wide area of aquatic water-bodies in the area, including the presently drained Lake Hula. It is suggested that in the Illies scheme of stream classification, River Dan might represent a type of stream belonging to a ‘pseudorhithral’ along with other stenothermic warm water torrents of the tropical-subtropical climatic belt.     

Circadian Typology and Emotional Intelligence in Healthy Adults

Several aspects related to health, such as satisfaction with life, perceived well-being, and psychopathological symptomatology have been associated with circadian typology and with emotional intelligence. Nevertheless, the relationships between circadian typology and emotional intelligence have not been explored yet. The purpose of the present study is to examine the relationships between circadian typology and emotional intelligence, taking into account the possible interactions between sex and physical exercise, and controlling for age. A sample of 1011 participants (649 women), aged between 18 and 50 yrs (26.92?±?6.53) completed the reduced Morningness-Eveningness Questionnaire (rMEQ) and the Trait Meta-Mood Scale-24 (TMMS-24). The TMMS-24 considers three dimensions of emotional intelligence: emotional attention, emotional clarity, and emotional repair. Women showed higher values for emotional attention, whereas men showed higher values for emotional repair (p?<?0.035, in both cases). Subjects who do physical exercise weekly showed higher values for emotional repair (p?=?0.001) regardless of circadian typology or sex. Circadian typology presents differences in all scores of emotional intelligence dimensions. Morning-type had lower emotional attention than evening- and neither-type; neither-type had lower emotional repair than morning-type, and lower emotional clarity than both evening- and morning-type (p?<?0.046, in all cases). Moreover, circadian typology modulated the sex differences in emotional attention, and only morning-type men showed a low emotional attention score. From the results of emotional intelligence we can conclude that morning typology may be a protective factor in terms of general health, whereas we should be aware that the neither-type may present a possible vulnerability to develop psychological problems.     

Designing Wetlands for Amphibians: The Importance of Predatory Fish and Shallow Littoral Zones in Structuring of Amphibian Communities

Under section 401 and section 404 of the Clean Water Act, permission to degrade existing natural wetlands in the USA may be conditional on restoring or creating ‘replacement’ wetlands. Success of wetland mitigation efforts in adequately replacing lost wildlife habitats depends on our good understanding of key ecological attributes that affect the structure of wetland faunal communities. We examined the effects of the presence of predatory fish, shallow vegetated littoral zone, emergent vegetation cover, wetland age and size on amphibian diversity in 42 replacement wetlands located in the Ohio’s North Central Tillplain ecoregion. We recorded 13 species of pond-breeding amphibians, and the average local species richness (α-richness) was 4.2 ± 1.7 species per site (range 1–7). There is strong evidence for the positive association between amphibian species richness and presence of a shallow littoral zone, and the negative association with presence of predatory fish. There was no evidence for the association between species richness and age, size, amount of forest cover within 200 m, nor the amount of emergent vegetation cover at the study sites. It is estimated that local species richness in wetlands with shallows was 1.76 species higher on average than in wetlands without shallows (95% CI from 0.75 to 2.76). The presence of predatory fish was associated with an average reduction in species richness by an estimated 1.21 species (95% CI from 0.29 to 2.11). Replacement wetlands were placed in areas with little or no existing forest cover, and amphibian species associated with forested wetlands were either rare (eastern newt, spotted salamander) or not present at all (marbled salamander, wood frog). In addition, we surveyed all replacement wetlands constructed under section 401 in Ohio since 1990, and found that predatory fish were present in 52.4% of the sites and that shallows were absent from 42.7% of the sites. Our results indicate that current wetland replacement practices could have a negative effect on the amphibian diversity within our region.     

Typology Reconsidered: Two Doctrines on the History of Evolutionary Biology

Recent historiography of 19th century biology supports the revision of two traditional doctrines about the history of biology. First, the most important and widespread biological debate around the time of Darwin was not evolution versus creation, but biological functionalism versus structuralism. Second, the idealist and typological structuralist theories of the time were not particularly anti-evolutionary. Typological theories provided argumentation and evidence that was crucial to the refutation of Natural Theological creationism. The contrast between functionalist and structuralist approaches to biology continues today, and the historical misunderstanding of 19th century typological biology may be one of its effects. This historical case can shed light on current controversies regarding the relevance of developmental biology to evolution.     

Aspects of population dynamics and feeding by piscivorous birds in the intermittently open Riet River estuary,Eastern Cape,South Africa

Aspects of the population dynamics and feeding activity of piscivorous birds in the small (c. 5 ha) intermittently open Riet River estuary, on the south-eastern coastline of South Africa, were investigated monthly from August 2005 to July 2006. A total of 188 birds of 13 species were recorded, of which six were wading piscivores, four aerial divers and three were pursuit swimmers. The Reed Cormorant (Phalacrocorax africanus) was the numerically dominant species, with a mean of 8.25 (SD ± 7.90) individuals per count. Mean numbers of the Pied Kingfisher (Ceryle rudis) and Giant Kingfisher (Megaceryle maximus) were 3.42 (SD ± 1.20) and 1.17 (SD ± 0.60) individuals per count, respectively. The remaining 10 species revealed mean values <0.5 individuals per count. Breaching events were associated with a change in feeding groups from waders to pursuit feeders, and a decrease in total bird numbers, most likely due to loss of potential littoral zone foraging habitat for waders resulting from reduced water levels. The highest bird numbers were recorded in winter reflecting the migration of large numbers of Reed Cormorant into the system. Monthly food consumption by all piscivorous birds showed large temporal variability, ranging from 26.35 to 140.58 kg per month.     

Induction of annual cyclical changes in the ichthyofauna of a large microtidal estuary following an artificial and permanent increase in tidal flow

The opening of a deep artificial and second entrance channel into the large Peel‐Harvey Estuary in south‐western Australia in 1994 provided a unique opportunity to determine the characteristics of the ichthyofauna of a microtidal estuary, in which tidal water movement and the rate of recovery of salinities in spring have both increased markedly. Fishes in the original entrance channel and both halves of the two large basins (Peel Inlet and Harvey Estuary), which constitute most of the total area of the estuary, were sampled using a 21·5 m long seine with a fine (3 mm) mesh bunt. The 72 337 fishes that were caught throughout the estuary and represented 43 species, comprised mainly marine species, both in terms of number of species (65·1%) and number of individuals (70·6%). The number of species and density of fishes in each region, and particularly in the basins, showed a pronounced tendency to decline from a maxima in summer to a minima in winter and then to rise in spring. Although the species composition of the fish fauna in the natural entrance channel differed significantly from that in each of the four basin regions, those within the basins were significantly different only in the cases of the southern Harvey Estuary versus both regions of the Peel Inlet. Species composition in the natural entrance channel and four basin regions each underwent conspicuous cyclical changes during the year, which reflected out‐of‐phase changes in the densities of certain species. Although this cyclical pattern was due mainly to changes in the densities of marine species, it was augmented by those of estuarine residents. The cyclicity, which was not evident prior to the opening of the artificial Dawesville Channel, and thus when tidal water movement within the estuary was far less pronounced, parallels the situation recorded for macrotidal northern hemisphere estuaries.     

Evaluation of Succession in an Estuarine Macrobenthic Soft-Bottom Community near Tampa,Florida

A subtidal macrobenthic infaunal community was quantitatively sampled monthly from February 1975 to July 1978 (42 months). During that period, complete defaunation (presumably due to hypoxia) occurred three times at approximately annual intervals. The recovery of the community was examined for successional patterns by quantitative and qualitative normal and inverse classification analyses and by rank-order analysis of the dominant species. There was no consistent pattern of succession from recovery to recovery. Samples taken just after defaunation were not similar to each other and no consistent suites of species were detected. Classical succession in which suites of species are successively replaced by other suites until a persisting suite of species occurs (faciliation model) was not found. Other models of succession are discussed.