Indian River Area Research Articles

Activated dolomite phosphate rock fertilizers to reduce leaching of phosphorus and trace metals as compared to superphosphate

Use of water-soluble phosphorus (P) fertilizers such as superphosphates (SP) has been increasingly concerned due to the loss of P and trace metals such as cadmium (Cd) into the environment. Activated phosphate rock holds promising as an alternate due to non-destructive and slow release nature. The objective of this study was to assess the leaching potential of P and trace metals from newly developed activated dolomite phosphate rock (HA-DPR and SLS-DPR), as compared to water-soluble fertilizers, including superphosphate (SP), diammonium phosphate (DAP) and original dolomite phosphate rock (DPR). Two representative agricultural soils (Alfisol and Spodosol soil) were sampled at the 0–20 cm depth from two farms for the column leaching experiments. Seven leachings were conducted at day 1, 3, 7, 14, 21, 28, and 56, respectively, and a total of 1050 mL of deionized water (equivalent to half year's rainfall in the Indian River area) was applied for leaching. Leachates were collected from each leaching event and analyzed for water-soluble P and metals. Activated DPR application led to an increase in soil pH by 1.4–1.7 units, whereas SP resulted in a decrease in soil pH by 0.4–1.6 units. P leaching from activated DPR were 33–61 times less than that from SP or DAP. HA-DPR and SLS-DPR treatments reduced cumulative trace metals in leachate by 1.3–12.3 times for the Alfisol soil, and 1.4 to 8.4 times for the Spodosol soil, respectively. These results indicate that activated DPR fertilizers are more environmentally friendly than water-soluble fertilizers.

Effect of Plant Growth Regulators and Fungicides on Huanglongbing-related Preharvest Fruit Drop of Citrus

The severe citrus (Citrus sp.) disease Huanglongbing (HLB), associated with Candidatus Liberibacter asiaticus, has resulted in widespread tree decline in Florida and overall citrus production is now the lowest it has been in 50 years. More than 80% of Florida citrus trees are HLB affected, and most growers attempt to sustain production on infected trees through good asian citrus psyllid (Diaphorina citri) control and enhanced fertilization and irrigation management. Although production appears to benefit from these treatments, preharvest fruit drop is considerably greater than on uninfected trees. U.S. Department of Agriculture (USDA) data indicate that Florida statewide fruit drop has increased by 10% to 20% of the entire crop in the last three growing seasons, essentially doubling the historical levels. Extensive research is underway to identify solutions to HLB, but it is essential to maintain production on existing trees to sustain the industry in the near term. For decades, several plant growth regulators (PGRs) have been labeled to reduce preharvest fruit drop in commercial citrus. Trials of these materials, other nonlabeled PGRs, and some fungicides were conducted in two seasons to determine if fruit drop could be reduced. Randomized complete block design experiments were established using four to six replications of four- to six-tree groups as experimental units, blocked spatially. In 2013–14, sprays of gibberellic acid (GA), 2,4-dichlorophenoxyacetic acid (2,4-D), 1-naphthaleneacetic acid (NAA), S-abscisic acid (S-ABA), aminoethoxyvinylglycine (AVG), and 1-methylcyclopropene (1-MCP) were applied once or twice alone or in some combinations at standard rates to trees in various mature blocks of ‘Valencia’ and ‘Pineapple’ sweet orange (Citrus sinensis), ‘Star Ruby’ grapefruit (Citrus paradisi), or ‘Murcott’ tangor (Citrus reticulata ×C. sinensis) in central Florida in the Indian River area. Only 1 of the 10 individual trials had treatments with significantly lower drop rates than controls; and when pooled across all experiments, GA + 2,4-D reduced number of fruit dropped per tree 4%, but only at P = 0.10. NAA, S-ABA, AVG, and 1-MCP had no effect and were not used the following year. Starting in 2014, treatments were initiated earlier in the season with greater effort to minimize variability: GA; 2,4-D; GA + 2,4-D; a natural GA, indolebutyric acid, cytokinin mix; and strobilurin fungicides were applied to 22 mature blocks of ‘Hamlin’ and ‘Valencia’ sweet orange trees. In 2014–15, only three of the 11 individual ‘Hamlin’ trials and one of the 11 ‘Valencia’ trials included a treatment with significant drop reduction compared with controls. However, when all the tests on ‘Hamlin’ were pooled, there was a significant 5% reduction in total crop drop for GA + 2,4-D and significant reductions with many of these PGRs alone, but in only one case with fungicide treatments. When all tests on ‘Valencia’ were combined, 2,4-D reduced drop significantly but only by 2% of the total crop (14% drop vs. 16% drop), but fruit drop in ‘Valencia’ blocks was near the historical average in control trees. Soil conditions and tree conditions were similar across all test sites and there were no apparent relationships between product efficacy and observed tree condition or any other grove characteristics. In addition, four ‘Hamlin’ and four ‘Valencia’ blocks were treated with 1/4 rates of 2,4-D + 6-benzyladenine every 45 days during the growing season (six sprays) and three of the eight individual trials showed significant reductions in drop: when pooled, these treatments reduced drop by 3% in ‘Valencia’ and 6% in ‘Hamlin’. At this time, PGRs cannot be recommended as a consistent way to reduce fruit drop related to HLB, but further work needs to be conducted to refine the most promising treatments.

Impacts of calcium water treatment residue on the soil-water-plant system in citrus production

Background and aims Long-term use of copper (Cu) based fungicides has accelerated Cu contamination in soils and subsequently its export to the environment. Field trials were conducted in representative commercial citrus groves in the Indian River area, South Florida to evaluate the effectiveness of calcium water treatment residue (Ca-WTR) for stabilizing Cu in soil and its subsequent influence on Cu loading in surface runoff and citrus growth.

Dissolved organic matter in relation to nutrients (N and P) and heavy metals in surface runoff water as affected by temporal variation and land uses – A case study from Indian River Area, south Florida, USA

Transport of dissolved organic matter in runoff water plays a critical role in the increased inputs of nutrients (N and P) and metals (Fe, Cu and Zn) in water, and the deposition of muck sediments in the Saint Lucie Estuary and Indian River Lagoon, Florida. The objectives of this study were to investigate the variation of dissolved organic carbon (DOC) and dissolved nitrogen (DN) in surface runoff water with varying land uses, and to explore their possible relations with the leaching losses of nutrients N and P, and metals Fe, Cu, and Zn from different land uses. For this, surface runoff water from two major agricultural production systems (citrus grove and vegetable farm) in south Florida was collected weekly using pre-installed autosamplers during Jan. 2008–Mar. 2010. Meanwhile, runoff water from twelve field sites with varying land uses (such as ranch, golf course, and forest) was collected monthly using a grab sampler from Aug. 2008 to April, 2010, and soils were collected at the depth of 0–15cm and 15–30cm twice a year from autosampler-installed locations and on Nov. 25th, 2008 from grab sampling locations as well. In the field, water samples were measured for electrical conductivity, dissolved oxygen, and temperature; in the laboratory, water samples were analyzed for pH, total solids, turbidity, DOC, DN, total P (TP), and metals Cu, Fe and Zn with or without passing a 0.45μm filter membrane. After passing a 2mm sieve, fresh soil samples were analyzed for moisture, pH, electrical conductivity, 0.5M K2SO4 solution extractable DOC/DN, and Mehlich 3 extractable P, Fe, Cu, and Zn. Spatial and temporal variations in the concentrations of DOC and DN in runoff water were observed, with the greatest average concentrations of DOC and DN from ranch (∼28 and ∼2.3mgL−1) and the lowest from golf course (∼16mgL−1) for DOC and from forest and nursery for DN (∼1.5–1.6mgL−1), respectively. Temporal fluctuations of DOC and DN in runoff water from varying land uses were in good accord with rainfall intensity and frequency of rainfall. Temporal variations of TP and metals Fe, Cu, and Zn were influenced by climatic condition as well. Citrus grove exported greater amounts of DOC and DN in runoff water (27.6 and 3.51mgL−1 of median value) than vegetable farms (13.8 and 2.26mgL−1 of median value). Annual cumulative loads of DOC and total N in 2008, 2009 or 2010 were >20kgha−1, greater than those of TP (<13.5kgha−1) and metals Fe, Cu, and Zn (<1.5kgha−1). Ranch soil had the highest extractable DOC concentration (>100mgkg−1), accounting for 1% of its total organic carbon. Soil extractable DN had significant correlations with extractable P and Cu/Zn in soils. In conclusion, soil total organic carbon pool and its availability had an important effect on DOC and DN in runoff water. Land use type and rainfall event were the two influential factors affecting concentrations of DOC and DN, and the export of nutrients N and P, and metals in runoff water.

Accumulation and availability of copper in citrus grove soils as affected by fungicide application

Purpose Copper is a trace element of environmental concern. Repeated applications of Cu-containing fungicides have resulted in a large scale of Cu contamination in agricultural soils. However, limited information is available regarding Cu accumulation and availability in soils under citrus production in the Indian River Area, South Florida, which has received increasing amounts of Cu fungicides to control canker and other diseases. The purpose of this study was to investigate Cu transformation, availability, and mobility in soils as affected by external Cu loading and soil properties. Materials and methods Soil samples (n=18) were collected from representative commercial citrus groves in the Indian River area. These samples were characterized to understand the accumulation, availability to plant, and leaching loss, as influenced by soil properties, agricultural practices, and Cu fungicide inputs. Results and discussion Significant accumulation and increased availability and mobility of Cu occurred in the soils with increasing citrus production period. Soil acidification enhanced Cu leaching in soil profiles. Available Cu estimated by Mehlich-3 or NH4OAc extraction was highly correlated with total recoverable Cu, whereas the relationship between CaCl2-extractable Cu and total recoverable Cu was affected by soil pH, with a greater slope of the relationship curve at soil pH<6.5. Vertical movement of Cu in a soil profile was more pronounced at pH<6.5. A large portion of soil Cu was present as organically bound, ranging from 43% to 62%, which was significantly correlated with both recoverable Cu and Mehlich-3extractable Cu (P<0.001). Conclusions Significant accumulation of Cu occurred in citrus grove soils due to anthropogenic inputs, and the availability and mobility of Cu in the soils were related to Cu accumulation and soil pH. Copper migration from Cucontaminated soils to the environment was reduced when soil pH was 6.5 or higher.

Made in China: Cancer Villages

High incidences of cancer have been reported for villages almost all over China and become an inescapable reality in polluted rural areas [16]. A new phenomenon has appeared in China: Aizheng Cun, ...

Evaluation of Dolomite Phosphate Rock–N‐Viro Soil Mixtures for Growth of a Horticultural Crop in an Acidic Sandy Soil

Most agricultural soils in the Indian River area, South Florida, are sandy with minimal holding capacity for moisture and nutrients. Phosphorus (P) leaching from these soils has been suspected of contributing to the eutrophication of surface waters in this region. Dolomite phosphate rock (DPR) and N‐viro soil are promising amendments to increase crop production and reduce P loss from sandy soils. Soil incubation and greenhouse pot experiments were conducted to examine the effects of Florida DPR–N‐viro soil mixtures on the growth of a horticultural crop in an acidic sandy soil and to generate information for developing a desired formula of soil amendments. Dolomite phosphate rock and N–viro soil application increased soil pH, electrical conductivity (EC), extractable P, calcium (Ca), and magnesium (Mg). N–viro soil had greater effect on soil pH, organic matter content, and microbial biomass than the DPR. Comparatively higher nitrification rates were found in the N–viro soil treatment than the DPR treatment. A systematic decrease in soil‐extractable P was found with increasing proportions of N‐viro soil from the combined amendments. Greenhouse study demonstrated that the application of DPR and N‐viro soil significantly improved dry‐matter yield and increased plant P, Ca, and Mg concentrations of radish (Raphanus sativus L.). Based on dry‐matter yield and plant N uptake, the combined amendments that contained 30% or 20% of DPR materials appear to be optimal but remain to be confirmed by field trials. Florida Agricultural Experiment Station Journal Series No. R‐11015.

Release Behavior of Copper and Zinc from Sandy Soils

Copper (Cu) and zinc (Zn) transport after agricultural applications have accumulated in the sediments and are suspected to affect fish health in the Indian River Lagoon and St. Lucie Estuary, South Florida. Minimal information is available on the release of soil Cu and Zn to water and its relation to their concentrations and physicochemical forms in the soils. Sandy soil samples (n = 13) with a wide range of total Cu and Zn content were collected from forestland and commercial citrus groves in the Indian River area, Florida. The soils were subjected to column leaching and batch extractions to understand the release behavior of Cu and Zn as affected by soil‐water contact time, soil/water ratio, pH, and electrolyte concentration and cations. Copper released in batch extractions that simulated long‐term leaching was primarily from exchangeable and carbonate‐bound fractions, whereas Zn was primarily from the carbonate‐bound fraction. The Cu and Zn released from the column represented short‐term leaching and were primarily from their exchangeable fractions. Leached Zn decreased linearly as the solution pH was raised from 3.0 to 9.0. Leached Cu was at a minimum at pH 5 to 7 and increased at higher or lower pH beyond that range. These results indicate that long‐term saturated conditions after precipitation enhanced Cu and Zn release to water from the sandy soils. The released Cu decreased with increasing Ca concentration but increased with sodium (Na) concentration in the soil solution because of their differential effects on soil colloids, especially organic matter (flocculated by Ca2+ and dispersed by Na+) because organically bound Cu is the dominant fraction in the soils. Increasing Ca, K, Na, or NH4+ concentration generally increased Zn release through cation exchange. These findings merit attention in the development of best management practices to reduce transport of heavy metals from land to water.

The influence of harvesting time and geographical location on susceptibility to physiological peel disorders associated with four Florida grapefruit cultivars

SummaryMajor cultivars of grapefruit (‘Flame’, ‘Ruby Red’, ‘Rio Red’ and ‘Marsh’) were harvested at 4–6 week intervals from Central Florida and the Indian River area on the Eastern Coast of Florida, from September through June 2001–2002 and 2002–2003. Generally, post-harvest pitting (PP) was less severe if fruit were harvested in February compared to fruit harvested after March. Chilling injury (CI) was high from October to December (early season), low from January to March (mid-season) and increased in all cultivars if fruit were harvested between April and June (late season). Higher PP and CI were found consistently in white ‘Marsh’ grapefruit than in coloured grapefruit cultivars; however, there was little difference in the incidence of CI and PP among three coloured cultivars. White grapefruit harvested from Central Florida developed more severe CI and PP compared to those from the Indian River area. These results are demonstrated in the factorial analyses of harvest month and cultivar or location over the 2 years of study. For commercial post-harvest management, the susceptibility of various cultivars to the development of peel disorder should be considered in association with the maturity and location of the harvested fruit.

Salinity Effects on Florida Grapefruit in the Indian River Region

A study was initiated in the 1997-98 production season to evaluate the effects of salinity on grapefruit yield and fruit quality in the Indian River area of Florida. The experiment was conducted on `Ray Ruby' grapefruit (Citrus paradisi) planted in 1990 on `Carrizo' citrange (C. sinensis × Poncirus trifoliata) and `Swingle' citrumelo (C. paradisi × P. trifoliata) rootstocks. Trees were planted on 15.2-m-wide (50 ft) double-row beds at a spacing of 4.6 m (15 ft) in-row × 7.3 m (24 ft) across-row [286.6 trees/ha (116 trees/acre)]. The control treatment was irrigated via microsprinkler emitters with water from a surficial aquifer well with an electrical conductivity (EC) of 0.7 dS·m-1. Higher irrigation water salinity levels were achieved by injecting a sea water brine mixture into the supply water to achieve ECs of 2.3, 3.9, and 5.5 dS·m-1. A wide range of rainfall and irrigation conditions occurred during the years encompassed by these studies, with rain totaling 1262, 1294, 1462, and 964 mm (49.7, 50.9, 57.6, and 38.0 inches) for 1997, 1998, 1999, and 2000, respectively. Salinity level had little effect on internal juice quality parameters [total soluble solids (TSS), acid, or juice content] at time of harvest. One of the most visible effects of irrigation with high salinity water was the damage to leaves, with leaf chloride (Cl) levels increasing about 0.14% for each 1.0 dS·m-1 increase in EC of the irrigation water for trees on `Carrizo' citrange and 0.02% for trees on `Swingle' citrumelo. For both rootstocks, the number of fruit and the size of the fruit decreased with increasing salinity in the irrigation water. The non-salinized trees had significantly larger fruit compared to the rest of the treatments. In the very dry 2000-01 season, trees on `Carrizo' irrigated with 0.7 dS·m-1 water had about 50% more fruit size 36 [fruit count per 0.028-m3 (4/5 bu) carton] or larger than trees watered with 3.9 or 5.5 dS·m-1 water. For trees on `Swingle' rootstock, trees irrigated with 0.7 dS·m-1 water had 150% to 200% more size 36 and larger fruit than trees watered with 2.3 dS·m-1 water. Over the four seasons, average yields for `Carrizo' were reduced 3200.0 kg·ha-1 (2855 lb/acre) per year for each 1.0 dS·m-1 increase in EC of the irrigation water. For `Swingle' rootstock, the reduction was 2600.3 kg·ha-1 (2320 lb/acre) per year for each 1.0 dS·m-1 increase in EC of the irrigation water. These reductions averaged 7% (`Swingle') and 6% (`Carrizo') for each 1.0 dS·m-1 increase in salinity of the irrigation water.

LEACHING OF MINERALS AND HEAVY METALS FROM MUCK-AMENDED SANDY SOIL COLUMNS1

There is a concern over potential leachability of minerals and heavy metals from agricultural soils following muck application. Leaching potential assessment of the minerals and heavy metals in the muck-amended soils is needed for beneficial use of muck in agriculture. A simulation leaching experiment of muck-amended soil columns was conducted to examine effects of muck application on concentrations of minerals and heavy metals in the leachates from two sandy soils. A clayey muck was collected from the St. Lucie Estuary and chemically characterized. Muck was applied to the top of the soil columns prepared from an acidic soil (Wabasso sand) and a calcareous soil (Winder sand) representing typical agricultural soils for commercial citrus production in the Indian River area at five different rates (0, 50, 100, 200, and 300 Mg ha -1 ). Deionized water (250 mL) was applied on a daily basis and repeated for 21 days. A total of 5,250 mL deionized water (equivalent to 1,130 mm rainfall) was leached, and the leachates were collected every 3 days and analyzed for pH, electrical conductivity, and concentrations of minerals and heavy metals. Most heavy metals in the muck sediments predominantly occurred in weakly mobile or nonbioavailable forms. The salts in muck sediments were easily removed from the amended soils by leaching. Electrical conductivity and minerals (Na, K, Ca, Mg) of leachates from the muck-amended soils were higher than soils without muck amendment. The electrical conductivity values and concentrations of the minerals increased with increasing muck rates, indicating that application of high amounts of muck sediments may increase salt concentration in vadose water. The muck application decreased P leaching from the acidic soil but also increased the concentrations of the heavy metals in the leachates. However, the concentrations of most heavy metals in the leachates were below drinking water limits, and percentages of accumulated heavy metals in the total added that was leached from the soils amended with different rates of muck were very low. Field trials may be needed to confirm the results from the column leaching studies because preferential flow may enhance leaching of metals under field conditions.

Economic Analysis of Aldicarb on Citrus in the Indian River Area in Southeastern Florida

Aldicarb is a pesticide used on several crops to control citrus rust mite (Phyllocoptruta oleivors), citrus nematode (Tylenchulus semipenetrans) and other citrus pests. Analysis of previous research experiments indicates that this pesticide is beneficial to both orange (Citrus sinensis) and grapefruit (Citrus parasisi) production and that both cost savings and higher yields can be experienced in many types of groves. Actual grove data shows that net returns for mature grapefruit that receive aldicarb can be $500/acre ($1235/ha) greater than net returns for identical acreage that uses other pest control options. Also, based on grove reset data, it is shown that with an application of aldicarb the resulting increased yields for 3-year-old trees more than cover the additional cost of applying the aldicarb.

Citrus Rootstock Usage, Characteristics, and Selection in the Florida Indian River Region

Sour orange (Citrus aurantium) has been the dominant citrus rootstock in the Indian River region of Florida since the initial plantings in the 1880s. Use of this rootstock in new plantings has been rare since 1990 because of heightened concern about decline strains of citrus tristeza virus (CTV), to which this rootstock is highly susceptible. Because the proportion of trees remaining on sour orange rootstock and the rate of decline among them are important in predicting the economic consequences for the Indian River citrus industry, two surveys of rootstock usage were conducted for citrus in this growing region. In the first survey, growers were asked about rootstock usage and problems observed across all types of citrus, and responses represented 35% of acreage. In the second survey, growers were restricted to rootstock usage and grower observations on decline for grapefruit (C. paradisi), and responses represented 53% of acreage. Even though 44% of all current Indian River grove area has been planted since 1987, when use of sour orange for new plantings largely ceased, 48% of all citrus and 55% of all grapefruit grove area are currently on sour orange rootstock. The percentage of grapefruit trees on sour orange rootstock that showed significantly health decline in 2000 was 8% based on grower reports. The other root-stocks representing substantial commercial grove area have known problems and limitations that are likely to prevent any of them from gaining the prominence once held by sour orange. Swingle citrumelo (C. paradisi × Poncirus trifoliata) at about 25% of grove area, Cleopatra mandarin (Citrus reticulata) at about 8%, and Smooth Flat Seville (Citrus hybrid) at about 3% all represented similar acreage for grapefruit and across all cultivars, while Carrizo citrange (C. sinensis × P. trifoliata) use was reported for 4% of grapefruit and 13% overall. Evaluation and development of new rootstocks is vitally important for the Indian River area, especially for soils with significant clay and calcium content.

Management of Citrus Root Weevils (Coleoptera: Curculionidae) on Florida Citrus with Soil-Applied Entomopathogenic Nematodes (Nematoda: Rhabditida)

The entomopathogenic nematodes Steinernema carpocapsae Weiser and S. riobravis Cabanillas, Poiner and Raulston were compared as twice a year soil treatments for control of the west indian sugarcane root stalk borer weevil, Diaprepes abbreviatus (L.), and citrus root weevil, Pachnaeus litus (Germar). Additionally, four single rate demonstrations evaluated S. riobravis and a 2- year test compared single versus double annual treatments of S. riobravis. The 6 experiments were conducted in the Indian River Area of Florida, U.S.A. Two applications per year of S. carpocapsae were as effective as S. riobravis for P. litus control but failed to control D. abbreviatus. A single application of S. riobravis delivering 2 million nematodes per tree through low volume irrigation systems or a tractor-mounted herbicide boom in demonstration tests provided 64% and 89% reduction of P. litus and D. abbreviatus, respectively. Single annual applications of 2 million S. riobravis per tree delivered with sprinkling cans reduced P. litus populations by 65% and D. abbreviatus populations by 85% over a 2 year period and was statistically equal to a 2-a-year treatment of S. riobravis that provided 80% and 95% reductions, respectively.

Lithofacies, petrography and environments of deposition, Tantalus Formation (Lower Cretaceous), Indian River area, west-central Yukon

ABSTRACT The Tantalus Formation in the Indian River area comprises interbedded sandstone, shale, conglomerate and coal that unconformably overlie Paleozoic (?) metamorphic rocks. It is informally subdivided into a lower, varicoloured chert pebble conglomerate and sandstone (approximately 50 m thick), and an upper, white quartz-vein pebble conglomerate and sandstone (approximately 450 m thick). The sediments are Early Cretaceous (Albian) in age and are intruded and unconformably overlain by volcanic rocks of the Carmacks Group (Upper Cretaceous). Twelve recurrent lithofacies are recognized in the conglomerate, sandstone, shale and coal on the basis of grain size and sedimentary structures. These are grouped into six lithofacies assemblages that are interpreted environmentally as an upper, subaerial fan-delta plain (conglomerate, and interbedded conglomerate-sandstone assemblages), a lower, subaerial fan-delta plain (interbedded sandstone-siltstone, and siltstone assemblages), and a subaqueous fan-delta plain (interlaminated siltstone-sandstone, and claystone assemblages). The fan-delta prograded south-westward into a paralic environment, the sediments being derived from Paleozoic sedimentary and metamorphic rocks exposed to the northeast. The Lower Cretaceous Tantalus Basin extended from west-central Yukon southeastward into British Columbia and had, at least, periodic connections to the sea. It formed during deformation of the Whitehorse Trough forearc basin and is classified as an intrasuture embayment basin. LITHOFACIES, PETROGRAPHIE ET MILIEUX DE SEDIMENTATION, FORMATION TANTALUS (CRETACE INFERIEUR), REGION DE LA RIVIERE INDIAN, PARTIE OUEST DU YUKON CENTRAL RESUME La formation Tantalus de la region de la riviere Indian est composee de gres, de schiste argileux, de conglomerat et de charbon interstratifies, en discordance avec des roches metamorphiques Paleozoiques (?) sousjacentes. Elle est officieusement subdivisee en deux parties, une inferieure composee de conglomerat a galets de chert multicolore, et de gres (approximativement 50 m d'epaisseur), et une superieure composee de conglomerat a galets de filon de quartz, et de gres (approximativement 450 m d'epaisseur). Les sediments datent du Cretace inferieur (Albien) et sont introduits et recouvert, en discordance, par les roches volcaniques du Groupe Carmacks (Cretace superieur). Douze lithofacies periodiques sont identifies dans les conglomerats, les gres, les schistes argileux et les charbons, en se basant sur la granulometrie et les structures sedimentaires. Ils sont ensuite regroupes en six ensembles de lithofacies qui sont interpretes, du point de vue milieu sedimentaire, comme suit: la partie superieure et subaerienne d'une plaine de cone de dejection (assemblages de conglomerat, et de conglomerat-gres interstratifies), la partie inferieure et subaerienne d'une plaine de cote de dejection (assemblages de gres-silt interstratifies, et de silt), et la partie sub-aquatique d'une plaine de cone de dejection (assemblages interlamines de silt-gres, et d'argilite). Le cone de dejection progressa en direction sud-ouest dans un milieu paralique, les sediments ayant leur source dans les roches sedimentaires et metamorphiques Paleozoiques affleurant au sud-est. Le Bassin Tantalus du Cretace inferieur s'etendit de la partie ouest du Yukon central, vers le sud-est dans la Colombie britannique et avait eu, au moins, des liens periodiques avec la mer. Il fut forme lors de la deformation du bassin avant-arc de la fosse de Whitehorse et est classe comme bassin de baie intra-suture. Traduit par Marc Charest

Additional K–Ar isotopic dates for the Carmacks Group (Upper Cretaceous), west central Yukon

Three whole-rock K–Ar analyses on andesites from the Indian River area, west central Yukon, yielded dates of 69.0 ± 1.7, 65.2 ± 1.7, and 64.8 ± 1.7 Ma. These confirm earlier dates indicating the Carmacks Group is Late Cretaceous in age. A single date of 51.4 ± 3.9 Ma was obtained from a tuff in the Sixty Mile River area, west central Yukon, suggesting an Eocene age for these deposits. However, this date is considered equivocal because it is anomalous when compared with the other dates from the area.

Hypothermal Mortality in Marine Fishes of South-Central Florida, January, 1977

Comparable climatic conditions on both coasts of central Florida resulted in cold induced fish mortalities from 19 January to 13 February 1977. Lethal temperatures, the species killed and their relative numbers killed are compared for the Indian River lagoon, Tampa Bay and Sanibel Island estuarine systems. Fifty-six species were killed in the Indian River area, 36 in the Tampa Bay area, while 19 died at Sanibel Island. The higher species mortality in the Indian River lagoon may be attributed to local hydrological and topographical conditions-and a richer ichthyofauna. Cold-induced mortality was noted in both juvenile and adult tropical fishes. Some tropical species appear to be more eurythermic than others as lethal minimum temperatures ranged from 6 to 13 C. Hypothermal stress and mortality were observed in offshore reef fishes.

Electrophoretic investigation of subpopulations of the spotted seatrout, Cynoscion nebulosus (cuvier), in the gulf of Mexico and atlantic coast of Florida

1. 1. Blood samples and eye lenses were collected from 500 spotted seatrout, Cynoscion nebulosus (Cuvier) at seven estuaries along the Gulf coast and in the Indian River area of Florida. 2. 2. Sera and eye lens extracts were processed by acrylamide gel electrophoresis and the banding patterns subjected to a population analysis. 3. 3. Each estuary was found to contain a discrete population of seatrout, differences among the populations increasing with geographic distance. 4. 4. Serum protein patterns provided a more sensitive method of detecting population differences than did lens proteins. 5. 5. Attempts were made to study the inheritance pattern of transferrins, but in every instance (194 serum samples) only a single band was present on each gel. 6. 6. A method is described for attaining satisfactory resolution without the time-consuming method of utilizing multiple layer gels.

Atlantic and Gulf of Mexico Menhadens, Genus Brevoortia (Pisces: Clupeidae)

Western North Atlantic menhadens, genus Brevoortia, comprise two well-defined groups, four species, several races, and two hybrid combinations. One group, the large-scaled menhadens, live in temperate waters and are represented by B. tyrannus in the Atlantic Ocean and B. partonus in the Gulf of Mexico. B. tyrannus occurs in the Atlantic from Nova Scotia to Jupiter Inlet, Florida. Populations include a spring-spawning race north of Long Island, N.Y., an autumn-spawning race on the coast between Long Island and North Carolina, and a winter-spawning race in the Indian River area of Florida. Evidence also indicates the existence of a southern Atlantic population that ranges from North Carolina to northeast Florida. B. patronus ranges from southwest Florida along the gulf coast to Veracruz, Mexico. The large-scaled manhadens support the fish oil and fish meal industry of the Atlantic and guif coasts of the U.S. The small-scaled menhadens are limited to warm-temperate waters. An Atlantic population of B. smithi is known from North Carolina to Jupiter Inlet, Florida. A gulf population of B. smithi ranges from Florida Bay to Louisiana. The western gulf cognate, B. gunteri, occurs between Louisiana and the Gulf of Campeche and may extend into the Caribbean. Two hybrid combinations are known. B. smithi x B. tyrannus ranges on the Atlantic coast from Sapelo Island, Georgia, to Jupiter Inlet, Florida. B. smithi x B. patronus ranges on the gulf coast from Florida Bay to Port St. Joe, Fla. Evidence is presented that B. tyrannus in the Indian River of Florida is modified by introgression. This study presents a key to the menhaden species and hybrids, describes the various forms, presents synonymies and recent references, and discusses hybridization, geographic variation, population structure, and zoogeography.

Budgeting Costs and Returns for Indian River Citrus Production, 2003-04

Budget analysis provides the basis for many grower decisions. Budget analysis can be used to calculate potential profits from an operation, to determine cash requirements for an operation, or to determine break-even prices. This report presents a budget constructed from current data and serves as a format for growers to analyze costs and returns from their individual records. Estimated costs and returns of growing seedless grapefruit in the Indian River area of Florida are presented for the twentieth year. The format presented may be used by individual growers to budget costs and returns, utilizing individual data on specific groves. September 2004.