Threats and knowledge gaps for ecosystem services provided by kelp forests: a northeast Atlantic perspective

Kelp forests along temperate and polar coastlines represent some of most diverse and productive habitats on the Earth. Here, we synthesize information from >60 years of research on the structure and functioning of kelp forest habitats in European waters, with particular emphasis on the coasts of UK and Ireland, which represents an important biogeographic transition zone that is subjected to multiple threats and stressors. We collated existing data on kelp distribution and abundance and reanalyzed these data to describe the structure of kelp forests along a spatial gradient spanning more than 10° of latitude. We then examined ecological goods and services provided by kelp forests, including elevated secondary production, nutrient cycling, energy capture and flow, coastal defense, direct applications, and biodiversity repositories, before discussing current and future threats posed to kelp forests and identifying key knowledge gaps. Recent evidence unequivocally demonstrates that the structure of kelp forests in the NE Atlantic is changing in response to climate‐ and non‐climate‐related stressors, which will have major implications for the structure and functioning of coastal ecosystems. However, kelp‐dominated habitats along much of the NE Atlantic coastline have been chronically understudied over recent decades in comparison with other regions such as Australasia and North America. The paucity of field‐based research currently impedes our ability to conserve and manage these important ecosystems. Targeted observational and experimental research conducted over large spatial and temporal scales is urgently needed to address these knowledge gaps.     

DendroSync: An R package to unravel synchrony patterns in tree-ring networks

Spatial synchrony refers to the presence of a common signal for a time-varying characteristic that, in dendrosciences, is shared among tree-ring chronologies from a particular area. Analysis and interpretation of synchrony patterns in tree-ring networks is currently limited by: (i) the requirement for flexible modelling of complex correlations and heteroscedastic errors and (ii) the availability of ready-to-use open software to fulfil this task. We present an R package (DendroSync) that facilitates estimating and plotting synchrony patterns for pre-defined groups. The package has been devised to work with traits derived from tree rings (e.g. ring-width), but other data types are also suitable. It combines variance-covariance mixed modelling with functions that quantify the degree to which tree-ring chronologies contain a common signal over a fixed time period. It also estimates temporal changes in synchrony using a moving window algorithm. The functionality and usage of DendroSync are illustrated using a simple example.     

Mixed Moment Estimation in Hermite Distribution and its Comparison with Other Estimation Procedures from Sample Size Considerations

In this paper (1) expressions (correct to n^?2 terms) for biases, variances, and covariances of the estimators a and b of Hermite distribution with probability generating function Exp[a(t–1) + b(t–1)] are obtained for two mixed moment estimates; (2) for the biases and variance-covariances, approximate regions of the parameter space (a>0, b>0) have been outlined where a sample of size 100 can be considered as “safe” in the sense that contribution of second order terms in them is 5% of that from the first order term; (3) comparison of the biases and variance-covariances of these two sets of estimators are made with those for the moment estimators, maximum likelihood estimates and the even point estimators for a sample of size 100 using the terms up to order n^?2; (4) the comparisons based on n^?2 terms in (3) have not only provided information on the estimation procedures included in the Hermite distribution, but also demonstrated the importance of higher order terms in the sampling properties of the various alternative techniques for the Hermite distribution.     

Elimination ofSitotroga cerealella (Olivier) bySitophilus zeamais Motschulsky from mixed laboratory cultures on maize

This paper describes a series of experiments conducted to determine why Sitophilus zeamaisMots . and Sitotroga cerealella (Oliv. ) could not survive together in maize cultures in the laboratory. The effect of S. zeamais on different developmental stages of S. cerealella was investigated. The presence of adult S. zeamais slightly affected moth copulation, egg laying and moth eggs in a mixed culture, but large numbers of developing moths inside maize grains were killed by the adult weevil through feeding on the grains. The major cause of elimination of S. cerealella by S. zeamais from mixed cultures was therefore found to be damage to the immature moths in grain and such moth mortality increased as the developing moths became bigger in the grains. A weevil: grain ratio of approximately 1.4∶1 was found to be the critical weevil density at which the moth disappeared from the mixed cultures.     

The effect of larval age range on survival of twoTribolium castaneum strains in mixed cultures,through pupal cannibalism

The effect of larval age range on survival of two Tribolium castaneum strains in mixed cultures was studied in an experimental situation in which other selective forces were reduced to a minimum. Increasing the difference in larval age setween the strains by one day resulted in a reduction of survival of the faster-developing mutant strain, because more of its earlier pupae were cannibalized by the larvae. General aspects of the effects of pupal cannibalism by larvae on the outcome of intra-specific competition (sensu lato) in Tribolium are discussed.     

A New Statistical Method for Mixed Variates Analysis in Epidemiological Research

Epidemiologically oriented research often may not do without observational or only partially controlled studies. In many such situations both qualitative characteristics and quantitative ones are observed. In literature there are different methods of handling such problems. The paper presents a method for analyzing dependencies resp. associations between random variates of any kind. The model concerned fullfills the whole field between analysis of variance, analysis of covariance and contingency table analysis. The method is named MIVA or mixed variates analysis, bases on the class of Conditional Gaussian Distributions of the exponential family and results in a unique system of mixed and unmixed measures of association–of pairwise, partial, multiple and global type. These measures are easy to be estimated and tested on significant deviation from zero. They may be used describing or analyzing dependence structures in many epidemiological studies but also in other fields.     

Mixed chemostat cultures of obligately aerobic and fermentative or methanogenic bacteria grown under oxygen-limiting conditions

Abstract Defined mixed cultures of an obligately aerobic Pseudomonas testosteroni and anaerobic Veillonella alcalescens strain were grown under oxygen and lactate limitation in chemostats with different oxygen supply rates. The aerobic and the anaerobic bacteria were shown to coexist and to complete for common substrates over a wide range of oxygen supply rates. Under similar conditions but with formate as the major substrate chemostat enrichments gave rise to undefined mixed cultures of aerobic, fermentative and methanogenic bacteria. The relevance of these observations to natural mineralization processes is discussed.     

Physiological heterogeneity in Lactobacillus casei fermentations on residual yoghurt whey

Lactobacillus casei is a well-known lactic acid-producer with substantial industrial interest. Currently, inexpensive lactic acid substrates such as residual yoghurt whey are being increasingly employed as revalorization strategies for such polluting food industry wastes. However, the influence of different bioprocessing conditions on the cellular functionality and physiological status of L. casei at single cell level has barely been evaluated to date. In the present study, monitoring the different physiological states of L. casei through multiparametric flow cytometry during lactic acid production from residual yoghurt whey showed that the majority of L. casei cells remained in healthy, metabolically active state (∼70%) under uncontrolled-pH conditions (pH <3.6), whereas a progressive increase in population heterogeneity was determined (increasing the damaged and dead subpopulations) with higher production (41.5 g/L lactate titer) and sugar consumption rates when a pH-controlled strategy at 6.5 was adopted. A segregated kinetic model was additionally developed to better describe the physiological behaviour of microbial heterogeneity, gaining deeper knowledge on the lactic acid-producing ability of each subpopulation under pH-controlled conditions in the mixed sugar co-fermentation. This study provides further understanding on the role of physiological heterogeneity in lactobacilli populations useful to enhance bioprocess performance and thus achieve efficient lactic acid production.