Southern Michigan Research Articles

PREDICTION OF LONG-DISTANCE DISPERSAL USING GRAVITY MODELS: ZEBRA MUSSEL INVASION OF INLAND LAKES

Gravity models are commonly used by geographers to predict migration and interaction between populations and regions. Even though rarely used by ecologists, gravity models allow estimation of long-distance dispersal between discrete points in heterogeneous landscapes. We developed a production-constrained gravity model to forecast zebra mussel (Dreissena polymorpha) dispersal into inland lakes of Illinois, Indiana, Michigan, and Wisconsin (USA) based on the site and location of lakes and the number and location of boats within 364 counties. A deterministic form of this model was used to estimate best-fit parameters for distance coefficient, Great Lakes boat-ramp attractiveness, and colonization cutoff threshold. A stochastic model thus developed from these parameters allows for random changes in colonization likelihood. The results of our model are highly correlated with the actual pattern of colonized lakes in southern Michigan and southeastern Wisconsin at the end of 1997. Areas of central Wisconsin and...

Prediction of Long-Distance Dispersal Using Gravity Models: Zebra Mussel Invasion of Inland Lakes

Gravity models are commonly used by geographers to predict migration and interaction between populations and regions. Even though rarely used by ecologists, gravity models allow estimation of long-distance dispersal between discrete points in heterogeneous landscapes. We developed a production-constrained gravity model to forecast zebra mussel (Dreissena polymorpha) dispersal into inland lakes of Illinois, Indiana, Michigan, and Wisconsin (USA) based on the site and location of lakes and the number and location of boats within 364 counties. A deterministic form of this model was used to estimate best-fit parameters for distance coefficient, Great Lakes boat-ramp attractiveness, and colonization cutoff threshold. A stochastic model thus developed from these parameters allows for random changes in colonization likelihood. The results of our model are highly correlated with the actual pattern of colonized lakes in southern Michigan and southeastern Wisconsin at the end of 1997. Areas of central Wisconsin and western Michigan, where zebra mussel colonies have not been documented, were also predicted to be colonized, suggesting that future invasions may be imminent in these locations. These analyses suggest that gravity models may be useful in predicting long-distance dispersal when dispersal abilities of species and the attractiveness of potential habitats are known.

Bivalve diets in a midwestern U.S. stream: A stable isotope enrichment study

This study examined a community of stream bivalves (unionids and fingernail clams) in a second‐order woodland stream in southern Michigan using both the natural abundance of 15N and a 6‐week whole‐stream 15N enrichment experiment, as part of the Lotic Intersite Nitrogen eXperiment (LINX). Objectives included addressing what made up the diet of these bivalves and whether suspended algae consumed by bivalves were derived from pelagic phytoplankton imported from an upstream lake or attached algae sloughed from instream surfaces. Within the examination of bivalve diets, we considered whether suspension‐ and/or deposit‐feeding modes were employed and whether bivalves selectively assimilated the algal and microbial portions of bulk material they ingested. All 12 unionid species reached a level of 15N enrichment greater than the bulk suspended organic matter. Sphaerium striatinum (Sphaeriidae) were enriched to levels greater than all presumed food sources. Suspended algae were derived both from sloughed epilithon and pelagic phytoplankton originating from lentic waters upstream. A mixing model suggested that unionids were consuming 80% deposited and 20% suspended material. Alternatively, these bivalves were preferentially assimilating the highly enriched living component of suspended and/or benthic organic matter rather than assimilating the bulk material. These results advance our understanding of freshwater bivalve‐feeding ecology, which is necessary if conservation efforts of these increasingly threatened organisms are to succeed.

Effect of Acupressure by Sea-Bands on Nausea and Vomiting of Pregnancy

To determine the effect of continuous acupressure at P6 applied by Sea-Bands with acupressure buttons on the frequency and severity of nausea and vomiting of pregnancy during the 1 st trimester.DesignA two-group, quasi-experimental, posttest-only and posttest-repeated measure.SettingSeventeen medical clinics or offices in southern Michigan.ParticipantsConvenience sample of Englishspeaking, healthy pregnant women in their 1st trimester, who had at least one episode of nausea, vomiting, or both before their prenatal clinic/office visit where they were recruited. After being accepted for the study, the women were randomly assigned to treatment or placebo groups.InterventionTreatment group 1 applied Sea-Bands with acupressure buttons to both wrists for 4 days and removed the Sea-Bands for 3 subsequent days. Placebo group 2 applied the Sea-Bands without acupressure buttons to both wrists on the same time schedule as group 1.Main Outcome MeasureSelf-report daily diaries of the number of times per day that participants experienced nausea, the severity of nausea, the number of vomiting episodes per day, and the severity of vomiting.ResultsMann-Whitney U procedures revealed that the treatment group had significantly less frequency and severity of nausea and vomiting of pregnancy while wearing the Sea-Bands than did the placebo group. The treatment group also had significantly less frequency and severity of nausea and vomiting of pregnancy while wearing the Sea-Bands than when not wearing the Sea-Bands.ConclusionsSea-Bands with acupressure buttons are a noninvasive, inexpensive, safe, and effective treatment for the nausea and vomiting of pregnancy. To determine the effect of continuous acupressure at P6 applied by Sea-Bands with acupressure buttons on the frequency and severity of nausea and vomiting of pregnancy during the 1 st trimester. A two-group, quasi-experimental, posttest-only and posttest-repeated measure. Seventeen medical clinics or offices in southern Michigan. Convenience sample of Englishspeaking, healthy pregnant women in their 1st trimester, who had at least one episode of nausea, vomiting, or both before their prenatal clinic/office visit where they were recruited. After being accepted for the study, the women were randomly assigned to treatment or placebo groups. Treatment group 1 applied Sea-Bands with acupressure buttons to both wrists for 4 days and removed the Sea-Bands for 3 subsequent days. Placebo group 2 applied the Sea-Bands without acupressure buttons to both wrists on the same time schedule as group 1. Self-report daily diaries of the number of times per day that participants experienced nausea, the severity of nausea, the number of vomiting episodes per day, and the severity of vomiting. Mann-Whitney U procedures revealed that the treatment group had significantly less frequency and severity of nausea and vomiting of pregnancy while wearing the Sea-Bands than did the placebo group. The treatment group also had significantly less frequency and severity of nausea and vomiting of pregnancy while wearing the Sea-Bands than when not wearing the Sea-Bands. Sea-Bands with acupressure buttons are a noninvasive, inexpensive, safe, and effective treatment for the nausea and vomiting of pregnancy.

Nitrogen uptake and transformation in a midwestern U.S. stream: A stable isotope enrichment study

This study presents a comprehensive analysis ofnitrogen (N) cycling in a second-order forestedstream in southern Michigan that has moderatelyhigh concentrations of ammonium (mean,16 μg N/L) and nitrate (17 μg N/L). Awhole-stream 15NH4+ addition wasperformed for 6 weeks in June and July, and thetracer 15N was measured downstream inammonium, nitrate, and detrital and livingbiomass. Ancillary measurements includedbiomass of organic matter, algae, bacteria andfungi, nutrient concentrations, hydrauliccharacteristics, whole-stream metabolism, andnutrient limitation assays. The resultsprovide insights into the heterotrophic natureof woodland streams and reveal the rates atwhich biological processes alter nitrogentransport through stream systems.

ABSTRACT: High Resolution Geologic Mapping of Northeast Southern Michigan

ABSTRACT: High Resolution Geologic Mapping of Northeast Southern Michigan

Morphologic evidence of lamellae forming directly from thin, clayey bedding planes in a dune

An excavation in a sand dune in southern Michigan revealed numerous, thin (<3 mm) clay-enriched strata between otherwise weakly stratified, clean, fine sand deposits. The parallelism of both the sandy and clayey strata suggest that they have direct geologic origins, having been deposited during formation of the dune. Although the clay-enriched strata and the intervening sandy layers are both within the sand textural class, the former contained between 3.0% and 5.4% clay, and the latter <1.8% clay. In areas of preferred leaching, such as below vertical root traces, the clayey strata thin out and become absent, or “bend downward”, become wavy and contorted, and take on the appearance of typical pedogenic lamellae. These observations support a theory of lamellae genesis that is both pedogenic and geogenic. Thin sedimentary strata may be pedogenically “transformed” into features that would normally be described as (entirely pedogenic) lamellae. Thus, many thin lamellae in Pleistocene-aged soils may simply be deformed and pedogenically altered sedimentary strata. This conclusion has implications for the nature and cyclicity of clay deposition in environments where thin lamellae are common in sandy soils.

Hibernacula of the Copperbelly Water Snake (Nerodia erythrogaster neglecta) in Southern Indiana and Kentucky

The copperbelly water snake, Nerodia erythrogaster neglecta, is the midwestern representative of the redbellied water snake (Conant, 1934; Conant and Collins, 1991). At the state level, the copperbelly is listed as Endangered by the states of Indiana, Ohio, and Michigan, and conferred special protected status in Illinois and Kentucky. At the federal level, the U.S. Fish and Wildlife Service (USFWS) lists the northern populations (in southern Michigan, northeastern Indiana, and northwestern Ohio) as Threatened. The southern populations (in southeastern Illinois, southern Indiana, and northwestern Kentucky) are protected by the Copperbelly Water Snake Conservation Agreement. A poorly understood aspect of the natural history of copperbellies is where they hibernate, both in terms of the structure of the hibernacola and location within the habitat. Understanding copperbelly hibernation has important implications for their conservation, impacting decisions concerning those human activities which remove suitable habitat, as well as governing recommendations for habitat reclamation and resto-

SPECIES INTRODUCTIONS AND THEIR ECOLOGICAL CONSEQUENCES: AN EXAMPLE WITH CONGENERIC SUNFISH

Pumpkinseed (Lepomis gibbosus) and redear sunfish (L. microlophus) are sister species with largely allopatric native ranges. For purposes of sport fishery enhancement, redear have been introduced into lakes of southern Michigan, and as a result, a large zone of artificial sympatry of pumpkinseed and redear has been created. Redear and, to a lesser extent, pumpkinseed are morphologically and behaviorally specialized molluscivores, and we hypothesized that introduced redear would have strong negative effects on pumpkinseed due to competition for snails, which are each species' main adult resource. Specifically, we predicted that redear would reduce snail availability, alter pumpkinseed diet, and reduce pumpkinseed growth and density. To examine these predictions, we surveyed pumpkinseed diets, growth, and densities, as well as snail availability in lakes with and without introduced redear. We also conducted a controlled field experiment (target–neighbor design) in which relative neighbor densities of each species were manipulated and the effects on target individuals of each species were measured. This experiment was designed to explore mechanisms underlying the competitive interactions suggested by the longer-term field study. Together, the field patterns and short-term experimental results demonstrate that the introduction of redear negatively affected the native pumpkinseed: (1) In lakes where redear had been introduced, the abundance of pumpkinseed declined an average of 56%, while average pumpkinseed abundance increased 60% in lakes without introduced redear. (2) In the presence of redear, pumpkinseed had fewer snails in their diets and showed only a weak ontogenetic niche shift to feeding on snails. (3) Snail biomass was ∼69% lower in lakes where redear had been introduced, and snail biomass was ∼50% lower in experimental treatments containing redear instead of pumpkinseed. In the experiment, pumpkinseed growth was reduced in the presence of redear. However, contrary to our predictions, pumpkinseed growth rates did not differ between lakes with redear vs. those without redear. We suggest that a reduction in pumpkinseed growth rate is an expected short-term response to redear introduction, whereas the long-term response is a reduction in pumpkinseed density.

Post-dispersal weed seed predation in Michigan crop fields as a function of agricultural landscape structure

Weed seed predation by invertebrates and vertebrates was compared between a simple (large crop fields embedded in a matrix of widely scattered woodlots and hedgerows) and a complex (small crop fields embedded in a matrix of numerous hedgerows and woodlots) agricultural landscape in southern Michigan. The structural differences between landscapes were evaluated by analysis of aerial photographs and digital land-use data. Seed predation experiments were conducted in four conventional tillage corn ( Zea mays L.) fields within each landscape type. Trials included four common agricultural weed species, i.e., crabgrass ( Digitaria sanguinalis), giant foxtail ( Setaria faberii), pigweed ( Amaranthus retroflexus), and velvetleaf ( Abutilon theophrasti). Treatments to exclude vertebrates, invertebrates + vertebrates and no exclusion were established at 27 m from hedgerows. Fields in the complex landscape were 75% smaller, had 63% more wooded perimeter, and 81% more wide hedgerow perimeter than fields in the simple landscape. Fields in the simple landscape were surrounded mainly by herbaceous roadside and crops, whereas the complex landscape had fields surrounded primarily by wide hedgerows. In both the landscape types there was considerable post-dispersal weed seed removal with a tendency towards higher removal rates in the complex landscape. Although there were no differences in the rate of seed removal among the four weed species, seed predation showed a high degree of variability within and among fields.

Independent and Interactive Effects of Crayfish and Darters on a Stream Benthic Community

A growing body of research suggests that direct and indirect interactions among consumers can have strong effects on the abundance of their prey. We examined the independent and interactive effects of 2 common freshwater consumers, crayfish (Orconectes propinquus) and rainbow darters (Etheostoma caeruleum), on benthic macroinvertebrates in a southern Michigan, USA, stream. A secondary goal was to assess the effects of crayfish and darters on the basal trophic level (periphyton) in the system. Presence and absence of crayfish and darters were manipulated in situ in wire mesh cages (0.2 m², 6-mm mesh) using a 2 × 2 factorial, randomized block design. Invertebrates and periphyton (for chlorophyll a analysis) were sampled biweekly for 6 wk from artificial rock substrates within these cages. Neither consumer significantly affected chlorophyll a accumulation. Darters alone had no significant effects on total invertebrate abundance. Crayfish alone caused, on average, a 58% reduction in total invertebrate abundance relative to exclosures, and most common invertebrate taxa were negatively affected. In the presence of darters, however, crayfish reduced invertebrate numbers by only 29% relative to exclosures. Daters apparently modified the ability of crayfish to suppress invertebrate abundance, although the mechanism is unclear. Evaluations of community structure based on manipulations of individual consumer species may be misleading when interaction modifications such as these occur.

Performance of Transverse Cracking in Jointed Concrete Pavements

Environmental effects and repetitive traffic applications can lead to the development of transverse cracks in jointed concrete pavements. Maintaining adequate aggregate interlock load transfer across these cracks is essential to preserving the functional and structural integrity of these pavements. The objectives of this study were to determine the design parameters that significantly affect transverse cracking and to demonstrate methods available for evaluating cracked pavements. Field data collected from in-service jointed concrete pavements located throughout southern Michigan were used to accomplish these objectives. Joint spacing, coarse aggregate type, shoulder type, and pavement temperature were found to have significant effects on transverse crack development and/or performance. The surface texture of crack faces was assessed using a promising new test method called volumetric surface texture testing. Volumetric surface texture results provided an indication of the aggregate interlock potential of pavements containing various aggregate types. Three performance parameters capable of mechanistically characterizing crack performance were discussed. A relatively simple procedure was described for determining these parameters and evaluating crack conditions. Field data were also used to demonstrate and validate a voids' analysis procedure. This procedure estimates the potential for loss of support near cracks and joints, thus allowing for proper rehabilitation actions to be taken prior to the manifestation of additional distresses.

Simplified Technique for Isolation, Excystation, and Culture of Sarcocystis Species from Opossums

Sarcocystis neurona is a protozoan parasite that causes a neurological disease in horses called equine protozoal myeloencephalitis. The route of transmission is speculated to be by fecal-oral transfer of sporocysts shed from opossums. Controversy exists regarding both the natural life cycle for this parasite as well as the species identity of opossum Sarcocystis. To provide stage-specific material for species comparison, 27 opossums from southern Michigan were screened for Sarcocystis spp. sporocysts. Seven opossums were positive for Sarcocystis sporocysts by fecal flotation. A simplified, effective technique for isolation, excystation, and culture of opossum Sarcocystis sp. from mucosal scrapings was developed. All 7 Sarcocystis sp. isolates were successfully cultured to grow long term in equine dermal cells to the merozoite stage. Merozoites were observed between 5 and 15 days after inoculation. In conclusion, opossums shed Sarcocystis sp. sporocysts that may be manipulated to excyst and grow in vitro in equine dermal cell lines to the merozoite stage using the simplified technique described.

Family involvement in the nursing home.

The focus of this study was the influence of preestablished family behavior patterns, family orientation of nursing home policies, and practices and caregiver and elder characteristics on the family members' expectations for involvement in the nursing home and the actual involvement 6 months later. The conceptual model was based on findings of Montgomery's nursing home study and open systems principles applicable to families. Data were collected through telephone interviews with 216 family members of residents in 24 nursing homes in southern Michigan. Regression analyses revealed that measures of preestablished patterns of family behavior accounted for 19% to 31% of variance in measures of expected family involvement. Expected family involvement, resident activities of daily learning (ADL), and caregiver relationship accounted for 11% to 23% of variance in measures of actual family involvement. Opportunity for family leadership in resident care had a mild effect of moderating the amount of family direct care and learning activities in the nursing home.

DOES AGRICULTURAL LANDSCAPE STRUCTURE AFFECT PARASITISM AND PARASITOID DIVERSITY?

This study evaluates whether previous observations of a higher percentage of parasitism and parasitoid diversity in a complex agricultural landscape, relative to a simple landscape, represent a general phenomenon. Rates of parasitism and parasitoid diversity of the armyworm (Pseudaletia unipuncta) were assessed in three replicate (On- ondaga, Ingham, and Benton) regions in southern Michigan. Within each region, a simple landscape (primarily cropland) and a complex landscape (cropland intermixed with mid and late successional noncrop habitats) were identified through analysis of aerial photo- graphs. In each landscape, three maize fields were selected, and second to fourth instar P. unipuncta were released into three replicate plots of maize plants. Larvae were recovered after 6 d and reared in the laboratory to record parasitoid emergence. A principal component analysis conducted on landscape variables indicated that simple and complex landscapes were true replicates. Extra-field vegetation was similar among the three simple landscapes but differed among complex sites. Parasitoid species diversity differed among regions, with six species recovered in Onondaga and two species from both Benton and Ingham. Rates of parasitism were only partially consistent with previous experimental results. In Ingham, results were similar to those found previously in this region; rates of parasitism and par- asitoid diversity were higher in the complex landscape. However, in Onondaga and Benton, no difference in rates of parasitism or parasitoid diversity were found. Thus, the hypothesis that landscape complexity increases parasitoid diversity and rates of parasitism was not supported. Possible reasons for the observed differences in rates of parasitism among regions are discussed.

Average Returns and Risk Characteristics of Site Specific P and K Management: Eastern Corn Belt On-Farm Trial Results

The objective of this study was to provide an economic assessment of site specific management (SSM) of P and K. The data were collected from 1993 to 1995 in farmer managed on-farm trials coordinated by Purdue University and DeKalb-Agra, a Waterloo, IN, agricultural input supply and marketing cooperative. Whole field management (WFM) was compared with SSM using either three acre grids or soil type for soil sampling and fertilizer recommendations. The data indicate that site specific P and K application on corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.) did not reliably increase net returns. The main effect of the site specific P and K applications on physical quantities of fertilizer was to redistribute the nutrient applications within fields. Both grid and soil type treatments had lower net return standard deviations than WFM. Both mean-variance and stochastic dominance (SD) analyses indicate that the soil type approach dominated the WFM for risk averse decision makers.

Plasticity and Selection Explain Variation in Tadpole Phenotype between Ponds with Different Predator Composition

Experiments demonstrate the existence of phenotypic plasticity in many organisms, and suggest that it can affect interactions among species. But rarely do we know whether naturally occurring phenotypic variation results primarily from plasticity, as assumed by the experiments, or also from processes such as local adaptation and viability selection. The data on predator-induced plasticity in amphibians are virtually all from artificial pond or laboratory experiments, so we sampled tadpoles of Hyla versicolor in two ponds with different numbers of predators, in southern Michigan, USA. Cornfield Pond had few predators, while Tinkle's Marsh (300 m away) had many predatory insects (11.4/m 2 ) and Ambystoma salamanders (1.0/m 2 ). Tadpoles from Tinkle's Marsh had shorter and shallower bodies than those from Cornfield Pond, and relatively long, deep, and brightly colored tails. We then asked whether the phenotypic difference could be predicted from experimental studies of plastic responses to the presence or absence of caged Anax dragonflies in cattle tanks, and of selection imposed by feeding Anax and in predator-free ponds. Plasticity accurately predicted observed population differences in traits such as tail color, tail depth, and body length. However, for some other traits, such as tail length and body depth, naturally occurring phenotypic variation was more likely produced by selection for divergent traits in the two ponds. We also collected tadpoles from both ponds and subjected them to free-ranging Anax in a short-term predation trial. Tadpoles from Tinkle's Marsh, where predators were common, survived 16% better, suggesting that naturally occurring phenotypic variation is associated with changing vulnerability to predation, as has been found for experimentally reared tadpoles. Our results show how experimental studies of plasticity and selection can be combined to predict phenotypic variation in nature, and suggest that such variation can modify species interactions.

Controls on the stable isotope composition of seasonal growth bands in aragonitic fresh-water bivalves (unionidae)

Water temperature, oxygen isotope composition and the δ 13C of dissolved inorganic carbon were measured in 2 southern Michigan rivers, the Huron River and Fleming Creek, between late September 1990 and June 1992. The final full year of shell growth in 3 unionids collected in 1992 from these rivers was sampled for stable isotope analysis with a resolution of 30 μm. The δ 18O of both shell nacre and the prismatic layer is accurately predicted by a fractionation relationship developed for biogenic aragonite. High resolution sampling of 3 species and bulk sampling of 3 other species suggest that all unionids adhere to this oxygen isotope fractionation relationship. This relationship is used to show that shell growth ceases below approximately 12°C. In these 2 settings the average δ 18O value of shell (PDB scale) is within 0.5‰ of the average δ 18O of river water (SMOW scale). Unionids can therefore be used in oxygen-isotope-based paleoclimatic and paleohydrologic reconstructions. In contrast, the carbon isotope ratio of shell is not accurately predicted by published fractionation factors between D.I.C. and carbonate. Shell δ 13C is more negative than predicted values and the offset is highly variable suggesting a significant and variable incorporation of metabolic carbon into the shell carbonate.

Palimpsest tunnel valleys: evidence for relative timing of advances in an interlobate area of the Laurentide ice sheet

AbstractDuring retreat from the lateWisconsinan maximum advance in the Great Lakes region of North America, the Laurentide ice sheet margin became distinctly lobate. The Lake Michigan, Saginaw, and Huron—Erie lobes converged in southern Michigan and Indiana, U.S.A. to form a complex interlobate region. Some time after the glacial maximum, the Lake Michigan lobe advanced over landscapes previously formed by the Saginaw lobe. This can be explained by an asynchronous advance of the Lake Michigan lobe during a Saginaw lobe retreat or by an increase in size of the Lake Michigan lobe relative to the Saginaw lobe during a synchronous readvance.Cross-cutting relationships in southwestern Michigan, including palimpsest tunnel valleys, document the overriding of Saginaw lobe terrain. Deep, generally straight trenches parallel to glacial flow lines with hummocky, irregular sides and bottoms are interpreted as tunnel valleys. Saginaw lobe tunnel valleys trend northeast—southwest and Lake Michigan lobe tunnel valleys generally trend east—west.At some time after a Saginaw lobe retreat in southern Michigan, the drumlinized landscape was overridden by an advance of the Lake Michigan lobe to an ice-marginal position at the Tekonsha moraine. Saginaw lobe tunnel valleys in the overridden area were completely filled with ice and debris from the Saginaw lobe retreat at the time of the Lake Michigan lobe advance. Supraglacial and proglacial sediments were deposited over the buried valleys by the Lake Michigan lobe, sometimes by meltwater streams that flowed at high angles to the trends of the valleys. After entrenchment of the Kalamazoo River valley, probably by a subglacial outburst flood, short tributaries were cut nearly at right angles across and through the debris and ice within several buried Saginaw lobe tunnel valleys. After the retreat of the Lake Michigan lobe, subsequent melting of ice in the palimpsest tunnel valleys exhumed the valleys, creating the cross-cutting relationships with the Lake Michigan lobe deposits.

Investigation of Design Parameters Affecting Transverse Cracking in Jointed Concrete Pavements

Environmental effects and repetitive traffic applications can lead to the development of transverse cracks in jointed concrete pavements (JCPs). Maintaining adequate aggregate interlock load transfer across these cracks is essential to preserving the functional and structural integrity of these pavements. The objectives of this study were to determine the design parameters that significantly affect transverse cracking and to demonstrate methods available for evaluating cracked pavements. Field data collected from in-service JCPs located throughout southern Michigan were used to accomplish these objectives. Joint spacing, coarse aggregate type, shoulder type, and pavement temperature were found to have significant effects on transverse crack development and/or performance. The surface texture of crack faces was assessed using a promising new test method called Volumetric Surface Texture (VST) testing. VST results provided an indication of the aggregate interlock potential of pavements containing various aggregate types. Three performance parameters capable of mechanistically characterizing crack performance were discussed. A relatively simple procedure was described for determining these parameters and evaluating crack condition. Field data were also used to demonstrate and validate a voids-analysis procedure.