Predation has long been implicated as a major selective force in the evolution of several morphological and behavioral characteristics of animals. The importance of predation during evolutionary ti...

Behavioral decisions made under the risk of predation: a review and prospectus

It is well documented that animals take risk of predation into account when making decisions about how to behave in particular situations, often trading-off risk against opportunities for mating or acquiring energy. Such an ability implies that animals have reliable information about the risk of predation at a given place and time. Chemosensory cues are an important source of such information. They reliably reveal the presence of predators (or their presence in the immediate past) and may also provide information on predator activity level and diet. In certain circumstances (e.g., in the dark, for animals in hiding) they may be the only cues available. Although a vast literature exists on the responses of prey to predator chemosensory cues (or odours), these studies are widely scattered, from marine biology to biological control, and not well known or appreciated by behavioural ecologists. In this paper, we provide an exhaustive review of this literature, primarily in tabular form. We highlight so...

The scent of death: Chemosensory assessment of predation risk by prey animals

The purpose of this revised Technical Support Document (TSD) for Water Quality-based Toxics Control is to provide the most current
procedural recommendations and guidance for identifying, analyzing, and controlling adverse water quality impacts caused by toxic discharges to the surface waters of the United States. The
original TSD was published in September 1985. Since then, the Clean Water Act (CWA) was amended in 1987 with an emphasis on controlling toxic pollutants. New policies and regulations
have been promulgated and a vast amount of knowledge and experienced has been gained in controlling toxic pollutants. Because of these changes, EPA revised and updated the TSD.

NOTE: Changes made to this document reflect corrections of typographical errors and the following update
of the interim guidance on criteria for metals: The Agency has issued “Interim Guidance Interpretation
and Implementation Aquatic Life Criteria for Metals.” The interim guidance supersedes criteria document
statements expressing criteria in terms of a acid soluble analytical method and also the metals
discusses of Section 5.7.3. The availability of this document appeared in the
June 5, 1992 Federal Register (Vol. 57, No. 109, pg. 24407).

Technical Support Document for Water Quality-based Toxics Control

Because food and habitat are closely linked for small herbivores that live on plants, food choice in the field may be constrained by the need to choose plants that provide safe living sites. We investigated the importance of food value and refuge value in determining the plant utilization patterns of the herbivorous marine amphipod Ampithoe longimana. When offered a choice of five common seaweeds, this amphipod fed most readily on Dictyota and Hypnea and less readily on Sargassum, Chondria, and Calonitophyllum. Rates of feeding on the different seaweeds were unrelated to seaweed gross morphology, toughness, nitrogen, or protein content. When cultured on each of these seaweeds in the laboratory, amphipod survivorship was high on Dictyota (82%), intermediate (35 and 18%, respectively) on Sargassum and Hypnea, and low (0%) on the other seaweeds. Survivorship on the different diets was strongly correlated (r = 0.930) with algal protein content; however, neither protein content nor amphipod performance on the different diets was significantly related to feeding rates on those diets. Additionally, amphipods from the three seaweed species that produced some survivors did not differ in growth rate, fecundity, egg size, or age at first ovulation. Variance in survivorship, and related measures, among sibling groups of amphipods suggested that this amphipod population possessed heritable variation for performance on the different seaweed species. In the field, abundance of A. longimana on the different species of algae was more clearly related to the preference of omnivorous fishes for these algae than to feeding rates of the amphipods when given those algae in the laboratory. A. longimana was more abun- dant on Dictyota and Sargassum (both unpalatable to omnivorous fishes), than on Hypnea, Chondria, and Calonitophyllum (all of which are palatable to fishes). During the season when omnivorous fishes were abundant, density of A. longimana increased on Dictyota, which is chemically defended from fishes, but decreased or remained unchanged on the seaweeds that are more palatable to fishes. Competition with other amphipods as a group did not appear to explain the distribution of A. longimana among seaweeds, since there were no negative correlations between A. longimana abundance and total amphipod abun- dance in any month. The lack of any consistent relationship between host-plant use in the field and either feeding preference or diet value, as measured by survivorship and repro- duction, suggests that host-plant use by A. longimana may be strongly constrained by requirements for shelter from predation.

/pdf/food-and-shelter-as-determinants-of-food-choice-by-an-31b8l0sxps.pdf

Food and Shelter as Determinants of Food Choice by an Herbivorous Marine Amphipod

European Union Risk Assessment Report

We examined patterns of habitat use of an isopod, Lirceus fontinalis, that coexists with predatory fish in second and third order permanent streams in central Kentucky, USA. Isopods were significantly more dense in Cladophora, a filamentous green alga, than on bare substrates of silt, sand, and gravel, and in submerged leaf litter when predatory fish were present. The dense, entangled filaments of the algae precluded most fish from entering Cladophora mats and eating isopods. Nonetheless, fish predation significantly reduced total isopod densities in these habitats. In laboratory manipulations, emergences from and entrances into Cladophora along with overall movements by isopods in open sandy areas were significantly reduced when green sunfish (Lepomis cyanellus) were present. Lirceus responded similarly to only water conditioned with green sunfish, indicating isopods use chemical cues, in part, to detect predatory fish. Isopods predominantly ate decaying leaf tissue (i.e., coarse particulate organic matter [CPOM] > 0.5 mm in diameter), but amounts of CPOM were significantly lower in Cladophora than in sediments of bare substrates. Lirceus did not eat the algae. Over 80% of the organic particulates in algal mats were < 0.5 mm (fine POM). Isopods reared on FPOM grew significantly slower than those on CPOM. Long-term use of algal mats poor in forage by isopods may adversely affect relative fitness since egg production by females is dependent on body size.

Habitat use and fish avoidance behaviors by the stream-dwelling isopod Lirceus fontinalis

Spatial changes in structural and functional characteristics of fish and macroinvertebrate communities in eastern Kentucky were investigated in a drainage system chronically exposed to high levels of chloride salts from nearby oilfield operations. Salinity levels at biological monitoring stations ranged from 0.12–31.3‰. Lotic regions with salinities greater than 10‰ were dominated by larvae of the dipterans Ephydra and Culicoides. In regions with salinities less than 10‰ species richness increased more or less linearly with decreasing levels of chloride salts. Ephemeropterans appeared to be one of the major invertebrate groups least tolerant of elevated NaCl levels and were absent in regions with salinities greater than 2‰ Availability of food resources, such as periphyton and particulate organic matter, did not appear to be grossly altered in disturbed regions, and it is suggested that the observed distribution of macroinvertebrate fauna was largely in response to taxonomic differences in salt tolerance. Fish seemed to be more tolerant of highly saline conditions, and several species were observed in regions experiencing salinities as high as 15‰. Accordingly, assemblages of fish taxa along the salinity gradient may have been influenced by trophic factors, such as spatial limitations in availability of invertebrate prey.

Ecology of a saline stream: community responses to spatial gradients of environmental conditions

A comparative ecological and toxicological investigation was conducted on a secondary wastewater treatment plant point—source discharge and the receiving system, a fourth—order freshwater stream in the Kentucky River basin Biological, chemical, hydrological and on—site toxicological studies were performed at 10 monitoring stations, including reference sites The principal objectives were to assess downstream persistence of aquatic contaminants, to quantify their effects on structure and function of aquatic communities and to evaluate the 8—d fathead minnow embryo—larval test for measuring instream toxicity and estimating chronic effects on aquatic biota The principal ecological endpoints included species richness, diversity (H'), density and dominance (D) of macroinvertebrates and diversity of fish species Macroinvertebrates were further analyzed by trophic groups Marked downstream gradients existed for effluent dilution, decreasing concentration of selected chemicals, improvement in ecological conditions and decreasing toxicity, as measured in on—site static—renewal tests A good predictive correlation was found between embryo—larval survival and independent ecological parameters, especially species richness of macroinvertebrates In addition, static—renewal and flow—through toxicity tests were performed with effluent dilutions to determine LC50 and toxicity threshold values (LC1), expressed as percent effluent by volume The estimated toxicity thresholds correlated closely with the actual percent instream effluent dilution observed at the first downstream station at which no ecological impact was discernible

A comparative ecological and toxicological investigation of a secondary wastewater treatment plant effluent and its receiving stream

We examined ontogenetic changes in diel patterns of habitat use and activity of the lotic isopod Lirceus fontinalis in relation to differences in predation risk from green sunfish, Lepomis cyanellus. Juveniles are ≤5 mm total length (TL), individuals 6-9 mm TL are mature females (c. 90%) and immature males, and mature males are ≥10 mm TL. Isopods of all sizes were far more dense in Cladophora, a filamentous green algae, than in open silt/sand substrates in fish pools. Densities of each size did not increase in open areas at night in fish pools when risk of predation presumably decreases. Few individuals of any size class occurred in open silt/sand areas in fish pools. However, habitat use did not depend on fish presence. Densities and relative abundances of all sizes were similar between algal and open habitats in fishless pools both day and night, except for mature males which were more abundant in open areas during daylight. All sizes of isopods were significantly more dense in fishless versus fish pools, and density of a size class was influenced by fish presence. Densities of size classes were typically juveniles > individuals 6-9 mm TL > mature males. Green sunfish are size selective feeders on isopods, thus demography of isopods within pools may be partially influenced by the size structure of the fish population.



Isopods reduced their activity, as measured by captures in benthic traps, in the presence of caged green sunfish only at night. This behavior coupled with relatively high activity levels during daylight regardless of fish presence suggests other predators or factors may influence diel activity. Mature males were overrepresented in traps relative to their occurrence in fish runs, indicating high activity levels. Mature males were also more active than gravid and nongravid females and juveniles in the presence of fish in laboratory aquaria. Number of male encounters with nongravid females depended on activity level.

Ontogenetic shifts in habitat use and activity in a stream‐dwelling isopod

Distribution of metals in water and sediments, as well as spatial alteration in the benthic macroinvertebrate and fish assemblages, was assessed in an alkaline headwater stream in eastern Kentucky receiving runoff from an abandoned surface mine. Concentrations of aluminum, copper, iron, manganese, and zinc generally increased 2 to 3 orders of magnitude in the receiving water immediately below where the mine runoff entered the creek. Metals in the water column were transported downstream largely in association with suspended particulates and declined in concentration progressively in a linear fashion commensurate to distance below the mine drainage outfall. In contrast, metal enrichment of sediments occurred spatially in a non-incremental pattern and varied among locations in conjunction with sitespecific changes in concentration levels of sediment organic matter. Benthic macroinvertebrate and fish fauna were eliminated for a distance of 0.3 km below the outfall, presumably owing to the presence of high levels of dissolved metals and low pH. Recovery of stream benthos occurred 1.0–2.0 km further downstream and was characterized by numerical dominance of collector-gatherer trophic groups consisting primarily of midge larvae (Chironomidae: Orthocladiini). Fish fauna in downstream reaches consisted exclusively of creek chubs(Semotilus atromaculatus) and stoneroller minnows(Campostoma anomalum). Metal levels in water and sediments remained elevated in regions of biological recovery and, as a consequence, downstream communities were comprised predominantly of metal tolerant taxa.

Terry M. Short

Papers

Habitat use and fish avoidance behaviors by the stream-dwelling isopod Lirceus fontinalis

Ecology of a saline stream: community responses to spatial gradients of environmental conditions

A comparative ecological and toxicological investigation of a secondary wastewater treatment plant effluent and its receiving stream

Ontogenetic shifts in habitat use and activity in a stream‐dwelling isopod

Effects of acid-mine drainage on the chemical and biological character of an alkaline headwater stream.