Arthur L. Buikema

DO SIMILAR COMMUNITIES DEVELOP IN SIMILAR SITES? A TEST WITH ZOOPLANKTON STRUCTURE AND FUNCTION

McCune and Allen (1985) asked the question “Will similar forests develop on similar sites?” and concluded that dissimilar old-growth forests had developed on similar sites due to historical factors (colonization, disturbance, etc.). We asked “Do similar zooplankton communities develop in similar ponds?” We compared zooplankton community structure and function in 12 newly constructed experimental ponds during 1 yr of natural colonization and analyzed a suite of physical–chemical variables to evaluate the assumption of environmental similarity among ponds. Ponds were similar for the measured environmental variables. However, zooplankton communities were structurally different, as indicated by analyses of species presence/absence, colonization and species accrual curves, and taxa (rotifer, copepod, cladoceran, and Chaoborus) density and biomass. Species varied widely in their colonization abilities. Zooplankton communities also differed in productivity of some taxa and community-level respiration rates. Scale was important in detecting structure and function differences among zooplankton communities. Species- and taxa-level analyses showed clear differences among communities, but community-level analyses of structure (species richness, total density and biomass) and function (productivity, respiration, and ammonia regeneration rates) could not identify distinct sets of communities. Community structure and function may be comparable in sensitivity for detecting change but need to be compared at equivalent scales. Dispersal (as evidenced by colonization history) was a regulator of new zooplankton communities, because it did not occur rapidly or uniformly among similar ponds. All zooplankton do not disperse readily. The extent to which dispersal limits older zooplankton communities is unknown, but genetic studies indicate low dispersal rates among established populations. Dispersal also regulates assemblages of organisms expected to be less vagile than zooplankton and in various ecosystems, indicating that “supply-side” and metapopchulation concepts are valuable for community ecology. Priority effects may have lasting influence on subsequent community structure, depending on colonization rates and sequences. We propose explicit recognition (and careful examination) of a commonly assumed but rarely tested “quorum effect”: local abiotic and biotic processes regulate communities and arrival processes do not, because potential members have already arrived. Given either priority or quorum effects, dispersal may be an important, often-overlooked process regulating community structure and function, especially when it is not rapid.

Phenolics in aquatic ecosystems: A selected review of recent literature☆

This review surveys the pertinent literature on phenolics in the aquatic ecosystem. Approximately 2% of the total organics manufactured in the US were phenols. Of the total phenolics produced in the US, 96% were synthetic and 4% were naturally occurring. Synthetic phenols arise from coking of coal, gas works and oil refineries, chemical plants, pesticide plants, wood preserving plants and dye manufacturing plants. Natural phenolics occur from aquatic and terrestrial vegetation and much of this is released by the pulp and paper industry. Toxicity of phenolics has been studied on selected microbes (e.g. protozoa, yeast and bacteria), algae, duckweed, and numerous invertebrates and vertebrates. Depending on the organism tested, the acute toxicity of phenol varies from 6·5 to 1840 mg/litre phenol. For other phenolics toxicity ranges from 0·084 to 555 mg/litre. The toxicity of phenolics varies with the type, position and number of substitutions on the parent molecule. Environmental factors affect the toxicity of phenolics and these include photolytic action, microbial degradation, pH, water hardness and temperature. Based on limited data, toxicity of phenolics may be less in continuous flow tests than in their sensitivity to phenolics as does the presence of oxygen. A seasonal factor may also affect the sensitivity of various fish. Starvation and lack of suitable substrate for bottom fauna increases organism sensitivity to phenol. The source of test animals may affect their sensitivity to phenolics and this effect may be due to short-term physiological acclimation and genetic selection. Studies on the biological effects of phenolics are limited and varied. Fish development and embryo survival were not affected by phenol levels less than 25 mg/litre. Amphibian embryos were sensitive to 0·5 mg/litre phenol. Pentachlorophenols inhibited fish growth at levels down to 1·74, μg/litre. Exposure of fish to phenol in concentrations as low as 4 mg/litre caused haemorrhaging at the base of the fins. Two hour exposure to 6·5 mg/litre phenol caused disruption of blood vessel walls and gill epithelium. Oedema and blood infiltration was a common effect observed in most major tissues studied from fishes exposed to phenol. Phenol, at 12·5 mg/litre, reduces the levels of neurohormones in fish exposed for 10 days. The effects of pentachlorophenol on blood glucose and blood lactate levels, and in vivo and in vitro activity levels of seven liver enzymes of eels are discussed. Pentachlorophenol, at 1·8 μg/litre, decreased assimilation conversion efficiency in underyearling salmon. Phenol also affects immunoglobin levels, blood protein levels and tissue micro-element levels. Feeding rates are affected by phenolics. Phenolics affect oxygen consumption rates and the effect may be on uncoupling of oxidative phosphorylation with a subsequent reduction of ATP formation. Many aspects of behaviour are affected by phenolics and the phases of ‘intoxication’ leading to death have been described for fish and invertebrates. Fish detoxify phenolics by forming conjugate glucuronides and sulphates. Body burdens of phenolics varied with exposure time and exposure concentration. When fish pre-exposed to phenol are transferred to clean water, body burdens drop up to 90% after three to four hours. Depuration rates for other phenolics took longer; up to 30 days for pentachlorophenol. Little research has been done on the cycling of phenol and phenolics (other than pesticides) in aquatic ecosystems. Microbial degradation will decompose phenolics rapidly if suitable bacteria are present. Other factors affecting the loss of phenolics from aquatic ecosystems include photolysis, adsorption and dilution. Phenol entering subterranean aquifers may not dilute or degrade very quickly. In one documented case well-water levels up to 200 mg/litre were measured 18 months after a spill.

Use of grass shrimp in toxicity tests

The literature pertaining to the use of grass shrimp in toxicity testing is reviewed. Information on the life history, species differences, collection, culture, handling, effects of toxicants, standard methods for toxicity testing, and potential problems in experimental design is presented. Suggestions for future research are made.

A simple method for screening petroleum effluents byin vitro enzyme Inhibition

This paper describes a rapid and inexpensive method for screening of petroleum effluents. A procedure is described for determining the extent of enzyme inhibition by a simulated petroleum effluent which contained conventional contaminants at maximum levels allowed to exist in a refinery effluent meeting 1977 guidelines (USEPA 1973).

Zooplankton of a swamp water ecosystem

The Great Dismal Swamp, located in southeastern Virginia and extending into northeastern North Carolina, is a unique ecosystem which has undergone severe alteration over the last 200 years due to agricultural, municipal and timbering development. The swamp is presently about 50% of its late 1700 size when George Washington commissioned the construction of the first of a series of drainage ditches that have subsequently reduced the swamp aquatic environs to a ditch network draining into Lake Drummond located near the swamps center. The swamp waters are characterized by a brown color, high suspended organic matter, high acidity and low nutrient levels. This paper presents the first comprehensive study of the zooplankton assemblages of the Great Dismal Swamp.Zooplankton was collected for one year at 14 stations and was dominated by rotifers. Of the 84 species identified, 61 were rotifers, 18 were Cladocera and 5 were copepods. Many of the species collected were cosmopolitan and acid tolerant forms. Dominant lake rotifers included Polyarthra vulgaris, Conochiloides dossuarius, Keratella cochlearis, Trichocerca similis, Synchaeta longipes and Microcodon clavus. Dominant crustaceae included Bosmina longirostris, Diaphanosoma leuchtenbergianum, Mesocyclops edax, and Tropocyclops prasinus.Usually the ditch zooplankton was the same as that of the lake. Of the seven ditches studied, the most unique chemically and biologically were Interior, Washington, and Portsmouth. Measurable alkalinity was detected in Interior and Washington Ditches. ‘Alkaline water’ rotifers such as Brachionus, Mytilina, Filinia, Notholca Platyias and Keratella earlinae were found in these ditches. The rotifer, Keratella valga, was only found from Portsmouth Ditch, during a period when water was flowing into the lake and it contained high nutrient levels.

A stressed stream ecosystem : macroinvertebrate community integrity and microbial trophic response

A year-long study of a second-order stream in Southwestern Virginia was carried out from 1979–80. One of the objectives of the study was to evaluate the effects of sewage and electroplating plant effluent stress on the trophic response of aquatic invertebrate assemblages and microbial communities in the stream. Quantitative benthic samples were collected periodically at three reference stations and four stressed stations below the outfalls. Invertebrates were counted, identified taxonomically, and classified into functional groups based on their feeding strategies. Ash-free dry weights were obtained for each functional group by date and station, and the number and density of different taxa were calculated as well. Reference stations had diverse invertebrate assemblages; scrapers were well represented and all functional groups were present in reasonably equivalent proportions. Stressed stations were dominated by collector gatherers and filterers to the virtual exclusion of scrapers. The trophic status of the microbial community was determined by suspending artificial substrates in the stream for 1-week periods. The community that colonized the substrates was assayed for ATP and chlorophyll a, and an autotrophy index (AI) was calculated using these values. The autotrophic component of the microbial community was greatest at the reference stations, and the community became primarily heterotrophic below the outfalls. The AI correlated well with the proportion of scrapers. Aquatic invertebrate assemblages and microbial communities responded to stress by changing their trophic structure to fit best the available energy sources. Where heterotrophic microbes dominated, gathering and filtering invertebrates utilized the abundant organic matter. In areas where a mainly autotrophic microbial community existed, scrapers, gatherers, and filterers were all present in balanced proportions.

Effects of sublethal concentrations of selenium on metabolism and filtering rate of Daphnia pulex

The purpose of this research was to evaluate the sublethal effects of selenium on Daphnia pulex oxygen consumption and filtering rate. Selenium is a trace element which is receiving increased attention as an environmental pollutant because of its high concentration in coal and other fossil fuels. It is the least plentiful and most toxic of the essential trace elements with a very narrow margin of safety between required and toxic doses.

A Seasonal Analysis of Stress in a Stream Ecosystem Using a Nontaxonomic Approach

A nontaxonomic method for monitoring stream community response to sewage stress was tested for 1 year on two small streams in southwest Virginia. The method represents an improvement in field testing approaches through increased replicability, decreased sampling time, and year-round applicability. Adenosine triphosphate (ATP) levels from microbial communities in organically stressed portions of Cedar Run were significantly higher than the unstressed portions of Cedar Run and Wilson Creek, whereas chlorophyll a levels were significantly lower. Microbial autotrophy indexes (AIs) calculated from the ATP and chlorophyll measurements increased significantly below the outfall. The AIs were inversely related to macroinvertebrate diversity and the number of taxa. Macroinvertebrate functional groups showed a balance between scrapers, collector-gatherers, and collector-filterers at all unstressed stations and a predominance of collector-gatherers or collector-gatherers and collector-filterers at the stressed stations. A significant inverse correlation was found between the AIs and the proportion of macroinvertebrate scrapers.

Evaluation of in vitro enzyme inhibition for screening petroleum effluents.

The purpose of this study was two fold: (1) to determine if in vitro inhibition of glucose-6-phosphate dehydroenose (G6PDH) can be used to predict toxicity of actual refinery effluents; and (2) to determine how inhibition of G6PDH varies as the components of an effluent artificial refinery mixture (ARM) vary.

COMPARISON OF BIOMONITORING TECHNIQUES FOR EVALUATING EFFECTS OF JET FUEL ON BLUEGILL SUNFISH (LEPOMIS MACROCHIRUS)

ABSTRACT The purpose of this study was to compare the effects of the water soluble fraction (WSF) of JP-4, a common military and civilian jet fuel, on survival, behavior, and physiology of bluegill sunfish ( Lepomis macrochirus ). The dynamic 96-hr LC50 for WSF JP-4 was 26.2% (percent of the maximum soluble amount of JP-4). A 5.1% WSF JP-4 caused a shift in ventilatory rate and amplitude; this concentration was equivalent to the 96-hr LC01. Fish displayed an avoidance reaction when exposed to 3.5 and 4.9% WSF JP-4. At higher concentrations approaching the 96-hr LC50, fish appeared to lose their ability to detect WSF JP-4 indicating a potential for fish not to avoid lethal concentrations. Few significant changes in whole and serum blood parameters were detected in fish exposed to 13% WSF JP-4; near the 96-hr LC50 changes were primarily attributed to osmoregulatory failure.