The need for clear and comparable terminology in benthic ecology. Part I. Ecological concepts

• 1. This note highlights problems with the definition and use of terminology in the field of benthic ecology, and compares the French classification with the UK and EUNIS classifications. These problems stem partly from language‐related difficulties, particularly the translation from English to French and vice versa, but also from the incoherence of certain typologies used in EU classifications and Directives.
• 2. The boundaries used by legislators and developers take neither ecological constraints nor environmental parameters into account. Most often, these boundaries are set using distances or depths that have no basis in the distribution of benthic species.
• 3. Retaining the definition of ‘étage’ that was proposed by Pérès (1961) is recommended, and the following classification hierarchy is proposed: supralittoral, mediolittoral, infralittoral with an upper littoral fringe, circalittoral with distinct coastal circalittoral and open circalittoral zones, bathyal, abyssal and hadal.

Copyright © 2007 John Wiley & Sons, Ltd.     

Effects of a Bacterial Inoculum in Channel Catfish Ponds

A commercial bacterial Inoculum cultured on site called Biostart was applied to three channel catfish Ictalurus punctatus ponds at Auburn, Alabama, USA, three times per week from May until October 1996. There were few significant differences (P × 0.1) in concentrations of water quality variables between ponds treated with bacteria and control ponds. In addition, bottom soil carbon and nitrogen did not differ between treated and control ponds. However, survival and net production of fish was significantly (P × 0.1) greater in ponds that received the bacterial inoculum than in controls. The mechanism by which the bacterial treatment influenced fish survival cannot be explained from data collected in this study. Further studies of probiotics are needed to define the potential benefits of these treatments to aquacultural production and to determine their mechanisms of action in pond ecosystems.     

Influence of variation in water temperature on survival,growth and yield of Pacific white shrimp Litopenaeus vannamei in inland ponds for low‐salinity culture

There is considerable interest in the culture of whiteleg shrimp (Litopenaeus vannamei) in inland low‐salinity water in Alabama and other states in the Sunbelt region of the US. However, the growing season is truncated as compared with tropical or subtropical areas where this species is typically cultured, and temperature is thought to be a major factor influencing shrimp production in the US. This study, conducted at Greene Prairie Aquafarm located in west‐central Alabama, considered water temperature patterns on a shrimp farm in different ponds and different years; and sought possible effects of bottom water temperature in ponds on variation in shrimp survival, growth and production. Water temperature at 1.2 m depth in 22 ponds and air temperature were monitored at 1‐hr intervals during the 2012, 2013, 2014 and 2015 growing seasons. Records of stocking rates, survival rates and production were provided by the farm owner. Correlation analysis and linear mixed model analysis of variance were used. Results showed that hourly water temperatures differed among ponds. The range of water temperature in each pond explained 41% of the variance in average final weight of shrimp harvested from each pond. In conclusion, the results suggest that variation in water temperature patterns has considerable influence on shrimp growth and survival in ponds.     

Electronic monitoring in fisheries: Lessons from global experiences and future opportunities

Since the beginning of the 21st century, electronic monitoring (EM) has emerged as a cost‐efficient supplement to existing catch monitoring programmes in fisheries. An EM system consists of various activity sensors and cameras positioned on vessels to remotely record fishing activity and catches. The first objective of this review was to describe the state of play of EM in fisheries worldwide and to present the insights gained on this technology based on 100 EM trials and 12 fully implemented programmes. Despite its advantages, and its global use for monitoring, progresses in implementation in some important fishing regions are slow. Within this context, the second objective was to discuss more specifically the European experiences gained through 16 trials. Findings show that the three major benefits of EM were as follows: (a) cost‐efficiency, (b) the potential to provide more representative coverage of the fleet than any observer programme and (c) the enhanced registration of fishing activity and location. Electronic monitoring can incentivize better compliance and discard reduction, but the fishing managers and industry are often reluctant to its uptake. Improved understanding of the fisher's concerns, for example intrusion of privacy, liability and costs, and better exploration of EM benefits, for example increased traceability, sustainability claims and market access, may enhance implementation on a larger scale. In conclusion, EM as a monitoring tool embodies various solid strengths that are not diminished by its weaknesses. Electronic monitoring has the opportunity to be a powerful tool in the future monitoring of fisheries, particularly when integrated within existing monitoring programmes.     

Evaluation of Hach Fish Farmer's Water Quality Test Kits for Saline Water

Hach Company Fish Farmer's Water Quality Test Kits (Models FF-2 and FF-1A) were compared with Standard Methods of analysis by determining dissolved oxygen, carbon dioxide, pH, total alkalinity, total hardness, chloride, total ammonia-nitrogen, and nitrite nitrogen in waters of 0, 17, and 30 ppt salinity. Results indicate that the kits generally are reliable for making routine water analyses of saline waters for practical aquacultural applications.     

Recent studies on the effects of DDT and pyrethroid insecticides on nervous activity in cockroaches

A summary is given of the results of three sets of electrophysiological experiments on the American cockroach (Periplaneta americana). The effects of DDT and S-bioallethrin [bioallethrin (S)-cyclopentenyl isomer] on single giant axons were studied using the voltage-clamp technique. Whereas both molecules induced long tails of inward (sodium ion) current, the voltage and time-dependency of these tails differed. With DDT, the tail was proportional to the activation of the peak current and decreased with the duration of the pulse, suggesting that the molecules were bound to open sodium channels and delayed their closing. With S-bioallethrin, the voltage dependency of the tail was different from that of the peak current, and the tail current increased exponentially with the duration of the depolarisation, suggesting that the pyrethroid insecticide modified resting (or silent) sodium channels into slowly activating channels. Modified action potentials, mimicking those produced by the two molecules, were computed on the basis of these results. Deltamethrin, one of the most potent pyrethroid insecticides, was applied topically on a leg mechanoreceptor and was found to have little effect on the local ‘receptor potential’ but to inhibit action potential production. The effects of topical applications of deltamethrin on the dorsal part of the abdomen, on nervous activity in the abdominal connectives, were studied under different experimental conditions. The results suggest that the insecticide molecules diffused rapidly through the cuticle, were concentrated in the haemolymph, and eventually reached the central nervous system, where they inhibited nerve activity.     

Multiscale sources of variation in ecological variables: modeling spatial dispersion,elaborating sampling designs

Detection of structured spatial variation and identification of spatial scales are important aspects of ecological studies. Spatial structures can correspond to physical features of the environment or to intrinsic characteristics of ecological processes and phenomena. Spatial variability has been approached through several techniques such as classical analysis of variance, or the calculation of fractal dimensions, correlograms or variograms. Under certain assumptions, these techniques are all closely related to one another and represent equivalent tools to characterize spatial structures.Our perception of ecological variables and processes depends on the scale at which variables are measured. We propose simple nested sampling designs enabling the detection of a wide range of spatial structures that show the relationships among nested spatial scales. When it is known that the phenomenon under study is structured as a nested series of spatial scales, this provides useful information to estimate suitable sampling intervals, which are essential to establish the relationships between spatial patterns and ecological phenomena. The use of nested sampling designs helps in choosing the most suitable solutions to reduce the amount of random variation resulting from a survey. These designs are obtained by increasing the sampling intensity to detect a wider spectrum of frequencies, or by revisiting the sampling technique to select more representative sampling units.     

Determination of CADESI-03 thresholds for increasing severity levels of canine atopic dermatitis

To evaluate the extent and severity of skin lesions in clinical trials enrolling dogs with atopic dermatitis (AD), the International Task Force on Canine Atopic Dermatitis recently recommended the use of the third version of the CADESI. This version of the CADESI was found to exhibit acceptable content, construct, criterion, inter- and intraobserver reliability and sensitivity to change. The current study was aimed at determining optimal CADESI-03 cut-off points to separate AD severity categories for future clinical trials. One hundred and eight dogs with AD were selected based on current diagnosis standards. At one or more visits, clinicians subjectively rated the severity of AD as 'in remission', 'mild', 'moderate' or 'severe', and a CADESI-03 score was then determined. In all, 158 CADESI-03 values were recorded and divided among the four disease severity categories. Receiver-operating characteristics (ROC) curves were generated at increasing cut-off values to determine the benchmark that would offer optimal sensitivity and specificity between adjacent categories. Cut-offs of 16, 60 and 120 are proposed at the interface of remission, mild, moderate and severe categories, respectively. Proposed intervals therefore are: remission: 0-15; mild AD: 16-59; moderate AD: 60-119; and severe AD: >/= 120. This Task Force recommends that, whenever applicable and relevant, subgroup analyses of outcome measures, based on disease severity as determined with these cut-off CADESI-03 values, be preplanned for clinical trials enrolling dogs with AD. Such subgroup analyses could help determine whether specific interventions might be more effective in a particular subset of atopic dogs.     

Family × Environment interactions in the growth and survival of Arctic charr (Salvelinus alpinus) grown in brackish and fresh water

We investigated whether Fraser strain Arctic charr Salvelinus alpinus L. reared in fresh water (FW) differed in survival and growth from full siblings transferred to brackish water (BW) and whether family performance was consistent throughout 1 year of commercial growth. Fish were grown communally (n = 3600) in either FW or BW from May 2008 to May 2009. Mean family survival in BW was moderately correlated with mean family survival in FW (r = 0.342; P = 0.032). Fish which survived until the conclusion of the experiment were significantly heavier in body weight at the baseline assessment than their full‐sibs which died. Family by treatment interactions were detected for body weight, condition factor and specific growth across all measurement dates (May 2008, October 2008 and May 2009) and growth intervals. Despite the varied response of families to treatment, mean family body weight in FW was correlated phenotypically with BW body weight in October 2008 (r = 0.633, P < 0.0001) and marginally correlated in May 2009 (r = 0.289, P = 0.061). These data suggest that body weight in FW and body weight in BW should be analysed as separate, but correlated traits in Arctic charr breeding programs.