Aflatoxin contamination of Virginia peanuts for the crop-years 1982–1986

To establish those environmental conditions which promote the growth of aflatoxin (AFT)-producing Aspergillus spp. on peanuts, a four-year (1982–1986) investigation was undertaken to examine possible relationships between air temperature (AT), precipitation (P), and AFT contamination of stored nuts. The mean percentages of nuts that possessed various AFT levels for the years 1982–1986 (June–July) ranged from 74·2 to 88·0 for 0–4 ppb, 6·3 to 14·9 for 5–15 ppb, 2·4 to 5·9 for 16–25 ppb, 2·3 to 6·4 for 26–100 ppb, and 0 to 4·7 for > 100 ppb. The mean percentages for the years which exceeded USDA/FDA regulations were 7·1 (1982–1983), 7·6 (1983–1984), 11·6 (1984–1985), and 17·0 (1985–1986). Examination of the mean percentage > 15 ppb for each month during these four years revealed that the following months fell within that range; Septtember, November, December, January, February, and May (1982–1983); July, October, April, and June (1983–1984); August, and June, (1984–1985); and July, April, and May (1985–1986). Comparisons of pooled-AFT levels, rainfall, and temperature over four years suggested a ‘better fit’ between mean monthly P and mean percentage AFTs > 15 ppb, than between the latter and mean monthly AT. However, application of a predictor equation suggested a correlation between AFT levels and monthly AT.     

History and dynamics of the crown-of-thorns starfish Acanthaster planci (L.) in the Suva area,Fiji

Annual recruitment of Acanthaster planci over a 13 year period in a known juvenile refuge substratum on Suva Reef was very patchy in time and space. Macroscale recruitment events resulted in outbreaks over many thousands of hectares over 100 km of coastline whereas localised but intensive mesoscale events resulted in concenrated aggregations over areas of several tens of hectares. A very low level of recruitment occurred in most years but three intensive, macroscale recruitment events occurred in 1977, 1984 and 1987, and two localised but intensive recruitment events occurred in 1982 and 1983. Annual recruitment of A. planci between 1975–89 had no overt relationship with rainfall events, as proposed in the terrestrial run-off hypothesis on the cause of primary out-breaks. Growth rates within monitored cohorts were highly variable, but mean growth rates of two cohorts 1984 and 1987 were relatively similar. Mortality rates of three monitored cohorts were variable. Longevity of the 1977 cohort was 7–8 years, while that of the 1984 cohort was 2–3 years. Mortality of the 1987 cohort has been low to date (i.e. 4 years of age). Disease, attributed to an undescribed sporozoan pathogen, was responsible for two mass mortalities in the 1984 cohort, in 1984 and in 1986, and eventually resulted in the extinction of this cohort. Anecdotal reports indicate that outbreaks of A. planci are increasing in frequency and severity. According to Fijian reef fishermen, the starfish were low to moderate in abundance in the Suva area from the 1920s to the 1960s. A progressive build up occurred on some reefs in 1963–67 leading to a major outbreak episode from 1967–1971. The outbreaks were in a chronic phase between 1977–1989. Our findings demonstrate that there is no invariable pattern or process involved in the population dynamics of A. planci and that a single explanation of the A. planci phenomenon is therefore unlikely.     

Changing female spacing behaviour and demography in an enclosed breeding population of Clethrionomys glareolus

The social organization of Clethrionomys glareolus Schreber was studied by live trapping in an enclosure of 0.8 ha in Central Finland between the years 1982–1986. The enclosure consisted of three habitats: abandoned field, brushwood, and moist spruce heath forest.
The population density increased from 50 voles ha⁻¹ in 1982 and 1983 to 150 ha⁻¹ in 1984 and 1985. In the summer of 1986 the population crashed to almost zero. In the summer of 1984 after winter breeding the number of breeding females grew to 22 compared with 6–7 in previous years. In 1984 the mature females changed from territorial to group behaviour.
During the high population density in 1984 and 1985 breeding stopped already in late July – early August, thus preventing any fence effect.
The present study supports the hypothesis stating that microtine social organization is an opportunistic strategy reacting phenotypically to changing environmental – especially food – conditions.     

Succession of cladocerans in a northern Italian ricefield

The seasonal succession of cladocerans was studied in an experimental ricefield (never treated with biocides) located on the Po River Plain (Province of Reggio Emilia) in 1982, the first year of rice cultivation, and in two later years, 1984 and 1986. A total of 26 species were identified; some of them were found in Northern Italy for the first time. The finding of Latonopsis australis Sars is discussed in detail. A trend of increasing specific diversity during the rice cultivation season was not recurrent every year. The most significant trends emerge when the three years are compared. The total number of species was 14 in 1982, 16 in 1984, and 20 in 1986. Diversity, too, increased strongly over the years: this trend was sustained chiefly by the increase in richness of Chydoridae species associated with the growth and decomposition of a large biomass of weeds and microalgae during the summer.     

Serological survey for selected diseases in the endangered San Joaquin kit fox (Vulpes macrotis mutica)

Blood from endangered San Joaquin kit foxes (Vulpes macrotis mutica) inhabiting the Elk Hills Naval Petroleum Reserve, Kern County, and the Elkhorn Plain, San Luis Obispo County, California, was collected in 1981, 1982 and 1984 and sera were tested for antibodies against 10 selected pathogens. Proportions of kit fox sera containing antibodies against pathogens were: canine parvovirus, 100% in 1981-1982 and 67% in 1984; infectious canine hepatitis virus, 6% in 1981-1982 and 21% in 1984; canine distemper virus, none in 1981-1982 and 14% in 1984; Francisella tularensis, 8% in 1981-1982 and 31% in 1984; Brucella abortus, 8% in 1981-1982 and 3% in 1984; Brucella canis, 14% in 1981-1982 and none in 1984; Toxoplasma gondii, 6% in 1981-1982; Coccidioides immitis, 3% in 1981-1982; and Yersinia pestis and Leptospira interrogans serotypes canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona, none in 1981-1982. Although antibodies against selected pathogens were present, no clinical indications of disease were observed in these fox populations.     

Submersed macrophytes and grazing crayfish: an experimental study of herbivory in a California freshwater marsh

Grazing by the crayfish Procambarus clarkii (Girard) on the abundance of submersed sago pondweed, Potamogeton pectinatus (L.), was quantified during 1984 through 1986 at Coyote Hills Marsh (Alameda County, California, USA). Annual marsh surveys indicated that P. pectinatus abundance declined (from 70% to 0% of the marsh surface), whereas P. clarkii abundance increased (from 1.6 to almost 3.0 crayfish trap⁻¹ week⁻¹). Crayfish in a 1425 m² trapping grid were non-aggregated when pondweed was abundant but became aggregated in the remaining pondweed beds as pondweed abundance decreased. In situ exclusion and enclosure experiments using crayfish densities of 0 to 3 individuals m⁻² were used to determine if crayfish reduced pondweed. Exclusion of crayfish from areas without pondweed, beginning in midsummer 1984, resulted in plant regrowth; addition of crayfish to these enclosed plots reduced pondweed. Exclusion of crayfish for the entire growing season in 1985 resulted in pondweed persistence in exclusion plots until August: in contrast, pondweed within adjacent, open control plots was eliminated by mid-June. Enclosure experiments showed a strong positive relationship between crayfish density and pondweed clearance. This study demonstrates that grazing crayfish can reduce and, in some cases, eliminate macrophytes from freshwater marshes.     

Long-term changes in the population size and geographical distribution of Pennella sp. (Copepoda) on the saury,Cololabis saira,in the western North Pacific Ocean and adjacent seas

Changes in the population size and geographical distribution of the mesoparasitic copepod Pennella sp. (Siphonostomatoida: Pennellidae) on the saury, Cololabis saira, were studied for a period of six years (1981–86) in the western North Pacific Ocean and adjacent seas. The parasite was first recorded in the western North Pacific in 1981. Its population size increased rapidly in 1982–83 and declined slightly in 1984. During these years, infected fish were widely distributed in the western and central North Pacific and also found in the Sea of Okhotsk and the Sea of Japan. However, the population declined dramatically in 1985 and its distributional range was reduced. The parasite disappeared in 1986. The observed frequency distributions of parasites on the host population were the Poisson in 1981 and 1985, but those during 1982–1984 were over-dispersed and fitted the negative binomial.Parasites of the saury, Cololabis saira (Brevoort)-IV.     

Year-to-year changes in the age structure of a caddisfly population following loss and recovery of a springbrook habitat

A severe drought in 1977 resulted in cessation of normally permanent flow m a northern California (USA) springbrook, and no individuals of the numerically dominant macroinvertebrate, the caddisfly Gumaga nigricula (McL), survived Prior to habitat loss (1976) this population was multiple cohort, two years after habitat recovery (1979) a single-cohort population was present The shift m age structure back to pre-drought conditions occurred gradually median head capsule width in 1976 (pre-drought) 0 39 mm, 1981 (post-drought) 0 95 mm, 1982 0 99 mm, 1983 0 59 mm, 1984 0 63 mm, 1985 0 63 mm, 1986 0 45 mm Age structure from 1981-1985 was significantly different (p < 0.001) from that occurring before habitat loss in 1976, age structure m 1986 was not significantly different from that in 1976 The ten-year time for return to the original population age structure could be influenced by the isolation of the springbrook from other colonization sources, gradual increases in population density, and differential growth reflecting food availability     

Serological Characterization of Actinobacillus Pleuropneumoniae Strains and Proposal of a New Serotype: Serotype 12

Until now 11 serotypes of Actinobacillus pleuropneumoniae have been described (Nicolet 1971, Gunnarsson 1980, Nielsen 1982, Rosendal & Boyd 1982, Nielsen & O’Connor 1984, Nielsen 1985, Kamp 1986). Recently a hitherto unrecognized serotype was isolated from 9 Danish outbreaks of pleuropneumonia in pigs. The origin of the strains is given in Table 1. From 3 herds the unrecognized serotype was found in 2 to 3 pigs submitted for necropsy at different times. The present study describes the serological properties of the 13 isolated strains.     

Habitat associations of Wood Warblers Phylloscopus sibilatrix breeding in Welsh oakwoods

Capsule Territory locations, density and the change in numbers over 20 years were associated with characteristics of the canopy, understorey structure and field-layer vegetation cover.

Aims To identify habitat characteristics associated with territory locations and density of Wood Warblers Phylloscopus sibilatrix in Welsh oakwoods in 2009–2011, and the change in abundance between 1982–1984 and 2003–2004.

Methods In 2009–2011, habitat characteristics were compared between 106 territories and 226 unoccupied points in 19 woods. Mean wood-scale habitat values were related to density in 27 woodland blocks. The change in Wood Warbler numbers between 1982–1984 and 2003–2004 was related to initial habitat quality in the 1980s and the change in habitat characteristics between the two time periods.

Results The location of territories in 2009–2011 was positively associated with canopy height, and with intermediate values of slope steepness, field-layer vegetation cover, canopy cover, the proportion of Oak Quercus in the tree community and subcanopy cover. Density was positively associated with slope, subcanopy cover at 0.5–2 m height and a landscape dominated by coniferous plantation and moorland; and with intermediate values of the proportion of oaks in the tree community. Wood Warblers declined by 24.4% in the two Welsh regions between 1982–1984 and 2003–2004, and trends were positively associated with the initial cover of Bramble and, in Gwynedd only, canopy cover.

Conclusions Wood Warblers were associated with a number of structural habitat variables, which could be related to the past management of the study woods. Management should be targeted at restoring habitat quality for Wood Warblers through the introduction of a moderate grazing regime.     

The relative importance of prey availability and intruder pressure in feeding territory size regulation by harriers,Circus cyaneus

Summary The relative importance of prey availability and intruder pressure in the regulation of harrier (Circus cyaneus) territory size was investigated over two years using analytical methods chosen to permit comparison with Myers et al. (1979) study of sanderlings (Calidris alba). Relationships between territory area and two variables, prey type (mice; large, medium, and small birds) and intruder type (conspecific neighbors, conspecific floaters, and heterospecific floaters), and the consistency of these relationships between years, also were examined. Individual harrier territory areas were highly variable, ranging from 7.8 to 1249 ha in 1984/1985, and 3.9 to 71.3 ha in 1985/1986. Of the prey variables, only mouse availability was significantly inversely correlated with territory area in both years, and slopes resulting from correlations between the logarithms of these two variables did not differ significantly from — 1, the expected result if harriers were adjusting mouse availabilities. The abundance of mice in conjunction with their greater ease of capture relative to birds made them functionally more available, and hence harriers' primary prey. This may explain why mice, rather than birds, were apparently the defended resource. Of the intruder variables, neighbor variables were most strongly inversely cortelatd with territory area. Partial correlation analyses to determine the relative importance of intruder pressure and prey availability in regulating territory size revealed that in 1984/1985, mouse availability and intruder pressure were relatively independent and each explained some variation in territory area, whereas in 1985/1986, mouse availability, rather than intruder pressure, significantly explained all variation in territory area. Possible explanations for why territory sizes of harriers appear to be regulated more closely by food density, whereas territory sizes of sanderlings appear to be regulated more closely by intruder pressure, are based upon differences in 1) neighbor effects, 2) environmental ronmental variability, and 3) accuracy of resource assessment by intruders. The variation in intruder rates and prey availabilities observed between years suggests the need to conduct studies over several years in order to assess accurately the relative importance of these variables in territory-size regulation.     

Human immunodeficiency viruses in patients attending a sexually transmitted disease clinic in London, 1982-7.

OBJECTIVE--To determine the prevalence of infection with the human immunodeficiency virus (HIV) in all patients attending a London sexually transmitted disease clinic over four weeks at the end of 1987 and to see how it varied from that in similar samples studied between 1982 and 1986. DESIGN--Anonymous testing of serum samples from consecutive heterosexual and homosexual patients having routine serological investigations for syphilis. Testing was for anti-HIV-I, anti-HIV-II, and hepatitis B core antibody (anti-HBc) and P24 antigen. Age, nationality, sexual orientation, and past sexually transmitted diseases were recorded for each patient. Gonorrhoea rates by quarters were analysed among homosexual and bisexual men and heterosexual men and women from 1981 to 1987. SETTING--Outpatient department of genitourinary medicine. PATIENTS--A total of 1074 patients attending consecutively for syphilis serology. Thirty five homosexual and bisexual men were excluded (these were regular attenders as part of a prospective study of the natural course of HIV infection). MEASUREMENTS AND MAIN RESULTS--The prevalence of anti-HIV-I in homosexual and bisexual men in 1987 was 25.6% (64/250). Results in the same clinic population between 1982 and 1984 had shown a rise in prevalence, which flattened out in 1985-6 and continued at that level. Among heterosexual attenders in 1987 the prevalence of anti-HIV-I was 1% (women 4/412; men 4/377), which contrasted with a prevalence of 0.5% (women 2/395; men 3/757) in January 1986. One homosexual man was seropositive for anti-HIV-II and seronegative for anti-HIV-I. Among homosexual and bisexual men the rate of gonorrhoea had declined by an average of 2.7% a year since 1981, such that by 1987--and for the first time in the clinic--there was no significant difference in the rates between these men and heterosexual men and women. CONCLUSIONS--The appearance of HIV-I infection among heterosexuals indicates a need for more aggressive education programmes and intervention strategies along the lines adopted for homosexual men. Surveillance for HIV-II infection is needed to provide information for future policy in national screening programmes.     

Long-term recovery of a mountain stream from clear-cut logging: the effects of forest succession on benthic invertebrate community structure

1. Changes in benthic invertebrate community structure following 16 years of forest succession after logging were examined by estimating benthic invertebrate abundance, biomass and secondary production in streams draining a forested reference and a recovering clear-cut catchment. Benthic invertebrate abundance was three times higher, and invertebrate biomass and production were two times higher in the disturbed stream.
2. Comparison of invertebrate community abundance 1, 5 and 16 years after clear-cutting indicated that the proportion of scrapers had decreased, whereas shredders had increased. Functional group percentage similarity indicated that the invertebrate community in the disturbed stream 16 years after clear-cutting was more similar to the reference than to that found earlier in the disturbed stream.
3. The five indices calculated from data collected over the past 16 years, as well as the abundance, biomass and production data collected during this study, proved to be of differing value in assessing recovery of the disturbed stream from logging. Percent dominant taxon and EPT (Ephemeroptera, Plecoptera and Trichoptera) taxon richness failed to show any initial differences between reference and disturbed streams, indicating that these indices may not be useful for measuring recovery from logging. The percentage Baetis and shredder–scraper indices showed significant differences only during the 1977 study and suggest recovery (no difference between reference and disturbed) by 1982. The North Carolina Biotic Index showed continued differences during 1982 in the riffle and depositional habitats and recovery by 1993. Total macroinvertebrate abundance, biomass and production, as well as EPT abundance, indicated continued differences between the reference and disturbed streams in the 1993 study.     

Effects of pollen and nitrogen availability on reproduction in a woodland herb,Lysimachia quadrifolia

Summary Relationships between pollen loads, resource availability, and fruit and seed production were determined for Lysimachia quadrifolia ramets in two adjacent sites (the scrub site and the open site) in 1982, 1983, and 1984. Pollen loads limited % fruit set and seed production in the open site in 1982 and 1983. Reproduction in the scrub site was resource limited in 1982, as shown by an increase in % fruit set when one-half of the flowers on a ramet were removed prior to fruit initiation. In the scrub site in 1983, pollination of one-half of the flowers on a ramet decreased the % fruit set of the remaining, unpollinated flowers. Fruit production in the same site was limited by pollen in 1984. Addition of nitrogen fertilizer to the scrub site in 1984 had no effect on fruit and seed production. There was more variation in fruit set between sites than between years. There was no trend to greater fruit set or number of seeds/fruit on early flowers compared to late flowers on the same ramet. Correlations between measures of reproduction were positive or insignificant. These results demonstrate year-and site-specific variation in the factors that limit plant reproduction.     

Trematode metacercariae of fishes as sentinels for a changing limnological environment

Trematode metacercaria populations infecting cichlids in Lake Kinneret (Sea of Galilee) were used as sentinels for the changing limnological environment. Parasitological data from 0+ cichlid fingerlings (Tilapia zillii, Oreochromis aureus, Sarotherodon galilaeus) were collected from the northwest shore of the lake during 1999 to 2001 and compared with data obtained from 1982 to 1984. The results show that the composition of the metacercarial populations changed significantly between the 2 samplings periods. The total number of metacercarial species found in the Kinneret cichlids was lower in 1999 to 2001 than in 1982 to 1984. Metacercariae transmitted by the snail Bulinus truncatus (Clinostomum tilapiae, Euclinostomum heterostomum, Bolbophorus levantinus and Neascus-type metacercariae--black spot and others) that were commonly found in 1982 to 1984 were absent from the fishes sampled during 1999 to 2001. The other trematode metacercariae (Centrocestus sp. and Haplorchis sp. transmitted by Melanoides tuberculata, Pygidiopsis genata transmitted by Melanopsis costata, as well as Phagicola longa, Strigeidae sp.1, an unidentified metacercaria typically found in the liver, and glochidia) increased in abundance in fishes sampled during 1999 to 2001. The calculated 'true' species richness of the habitat, extrapolated as a function of sampling effort, was significantly lower in the 1999 to 2001 versus 1982 to 1984 samples, while significantly fewer fishes needed to be sampled ('sampling effort') during 1999 to 2001 in order to reach the 'true' species richness. The higher calculated values of species richness and diversity for the 1999 to 2001 samples despite the overall decline in species number is explained by the overall increase in metacercariae prevalence.     

Large-scale patterns of Nodularia spumigena blooms in Pyramid Lake,Nevada, determined from Landsat imagery: 1972–1986

Magnitude and long-term periodicity of summer-autumn blooms of the nitrogen-fixing cyanobacterium, Nodularia spumigena, were characterized for hyposaline Pyramid Lake, Nevada, from Landsat MSS band 3 film negatives. Predicted lakewide mean chlorophyll a concentrations for Landsat overpasses during the July–October Nodularia bloom season ranged from 27 to 72 mg m^–3 with an overall average concentration of 32 ± 7 mg m^–3 between 1972 and 1986. Nodularia blooms were usually annual events. Blooms were not observed on Landsat images in only three of 15 years (1973, 1980, 1982) and midsummer calcium carbonate whitings occurred in two of these years (1973, 1980). Magnitude of Nodularia blooms was highly variable among years and very large blooms, where maximum mean chlorophyll a concentration exceeded one standard deviation of the 15 year overall mean (> 39 mg m^–3) appeared in 1974, 1975, 1977, 1979, 1984, 1985 and 1986. Very large early-July blooms always occurred during or following years of above average fluvial discharge to Pyramid Lake (1984–1986) and were associated with meromixis produced by the large influx of freshwater.Several problems arise using Landsat remote sensing to estimate magnitude and periodicity of scum-forming blue-green algal blooms. These complications may reduce accuracy and precision of phytoplankton biomass estimates made from Landsat images. Nevertheless, Landsat remote sensing enabled us to quantify relative bloom magnitude with limited collection of ground-based data and at a large-scale temporal and spatial resolution not possible using alternative methodologies.     

Anatomy of an outbreak of jack pine budworm, <Emphasis Type="Italic">Choristoneura pinus pinus</Emphasis> (Lepidoptera: Tortricidae)

We report data collected over the entire course of an outbreak of jack pine budworm, Choristoneura pinus pinus Freeman (Lepidoptera: Tortricidae), between 1984 and 1988 at 12 plots in Manitoba. The positive relationship between the level of defoliation, used as a proxy for population density, and the abundance of eggs suggests local reproduction by females. The density of pollen cones apparently reduced larval fitness in 1986, when flowers were least abundant, but had limited impact in other years when pollen cones were abundant; this suggests that the relative abundance of pollen cones is more likely to influence the termination of an outbreak than its onset. Considering the conditions that prevail at the onset of the outbreak (low defoliation combined with a high abundance of eggs), a predictive tool may be developed to anticipate outbreaks of jack pine budworm based on environmental conditions that are conducive to high survival and/or fecundity of females.     

Epidemiological analysis of testicular malignant neoplasm incidence and mortality in Poland 1963-1986

Epidemiological analysis of both morbidity and mortality rates for testicular cancer in Poland between 1963 and 1986 was carried out. A particular attention was drawn to the period between 1981 and 1986, when a program of combined chemotherapy and surgery was introduced in Poland. The study aimed at analysing an effect of this combined treatment on mortality rate for testicular cancer. Between 1963 and 1986, a constant increase in morbidity for the testicular cancer was noted. Mortality rate increased between 1963 and 1983. This trend was inhibited between 1984 and 1986. "Splitting" of the morbidity and mortality curves was observed between 1984 and 1986. A decrease in mortality rate was noted at the constant morbidity for testicular tumors. It was particularly clear in younger age groups (15-39 years), as well as older age groups (60-64 years and over 75 years). A decrease in mortality rate for testicular tumors within 1984-1986 may be attributed to the introduction of combined treatment in Poland.     

Effects of Continuous Cropping of Resistant and Susceptible Cultivars on Reproduction Potentials of Heterodera glycines and Globodera tabacum solanacearum

The reproductive potentials of Heterodera glycines (mixture of races 3 and 4 and unidentified races) and a tobacco cyst nematode Globodera tabacum solanacearum were studied in the field. The experiments involved four cultivars of soybean Glycine max and four cultivars of Nicotiana tabacum. The reproductive potential of the H. glycines population was high on Essex and Lee 74 soybean but low on Forrest and Bedford over the 3 years (1982-84) of continuous cropping. The reproductive potential of H. glycines was 12% on Forrest and 6% on Bedford in 1982 but increased to 37 and 35% in 1983 and to 71 and 41% in 1984, respectively, on these two cultivars. The reproductive potential of G. tabacum solanacearum was high on McNair 944 and Coker 319 tobacco cultivars and low on VA 81 and PD 4 over the 3 years of cropping. The reproductive potential of G. tabacum solanacearum on VA 81 and PD 4 was 18 and 17% in 1982, 7 and 16% in 1983, and 5 and 5% in 1984, respectively. The changes in reproductive potentials of H. glycines and G. tabacum solanacearum may be related to inherent genetic variability in the systems that control reproduction of the two cyst nematodes and nature of resistance incorporated in the soybean and tobacco cultivars.     

LONG-TERM TRENDS IN ABUNDANCE AND DISTRIBUTION OF MANATEES (TRICHECHUS MANATUS) IN THE NORTHERN BANANA RIVER, BREVARD COUNTY, FLORIDA

Four aerial survey projects were conducted between 1977 and 1986 to determine the abundance, density and distribution of West Indian manatees (Trichechus manatus), in the northern Banana River, Kennedy Space Center, Florida. Manatee density and distribution within selected portions of the 78.5 km² study area were determined. Peak numbers of manatees occurred in spring of each year. The maximum counts increased from 56 in 1978 to 297 in 1986. Manatee abundance was lowest in the winter of each year. Mean density per flight increased from 0.52 manatees/km2 in 1977–78 to 2.73/km² in 1984–86. This increase may reflect increases in the east coast population or shifts in the population distribution. Distributional changes were observed in the study area through time, with a lower percentage of manatees occurring in industrial areas and a correspondingly higher percentage of manatees in nonindustrial areas by 1985.