In-hive patterns of temporal polyethism in strains of honey bees (Apis mellifera) with distinct genetic backgrounds

Honey bee workers exhibit an age-based division of labor (temporal polyethism, DOL). Younger bees transition through sets of tasks within the nest; older bees forage outside. Components of temporal polyethism remain unrevealed. Here, we investigate the timing and pattern of pre-foraging behavior in distinct strains of bees to (1) determine if a general pattern of temporal DOL exists in honey bees, (2) to demonstrate a direct genetic impact on temporal pacing, and (3) to further elucidate the mechanisms controlling foraging initiation. Honey bees selected for differences in stored pollen demonstrate consistent differences in foraging initiation age. Those selected for increased pollen storage (high pollen hoarding strain, HSBs) initiate foraging earlier in life than those selected for decreased pollen storage (low pollen hoarding strain, LSBs). We found that HSBs both initiate and terminate individual pre-foraging tasks earlier than LSBs when housed in a common hive environment. Unselected commercial bees (wild type) generally demonstrated intermediate behavioral timing. There were few differences between genotypes for the proportion of pre-foraging effort dedicated to individual tasks, though total pre-foraging effort differences differed dramatically. This demonstrates that behavioral pacing can be accelerated or slowed, but the pattern of behavior is not fundamentally altered, suggesting a general pattern of temporal behavior in honey bees. This also demonstrates direct genetic control of temporal pacing. Finally, our results suggest that earlier HSB protein (pollen) consumption termination compared to LSBs may contribute to an earlier decline in hemolymph vitellogenin protein titers, which would explain their earlier onset of foraging.     

Efficacy of rapeseed residue and eggshell waste on enzyme activity and soil quality in rice paddy

Addition of plant residue into soils improves soil physiochemical properties and its fertility. Rapeseed residue is an emerging N source to paddy soils via rice-rape double-cropping practice. The objective of this study was to evaluate the effects of rapeseed residue and eggshell waste on chemical changes and enzyme activity in the rice paddy soil. The powdered eggshells at 0, 1, 3, and 5% were applied once to 7.0 kg paddy repacked soils in each pot treated with the rapeseed residue or the conventional N, P, and K fertilisers. Eight rice seedlings (Oriza sativa L. cv. Ilmibyeo) (40 days after sowing) were transplanted to the treated each pot. The contents of total C (TC) and N (TN), and organic matter (OM) were significantly increased in soils treated with the rapeseed residue compared to the N, P, and K fertilisers. With the addition of eggshell containing ～92% CaCO₃, a considerable increase of soil pH was observed in soils treated with the rapeseed residue and the N, P, and K fertilisers, compared to the untreated soil. Activities of β-glucosidase, urease, and arylsulfatase enzymes were higher in soils treated with the rapeseed residue than soils treated with the N, P, and K fertilisers. The eggshell additions at 1, 3, and 5% into soils treated with the rapeseed residue increased enzyme activity mainly resulting from N mineralisation, whereas no change in enzyme activity was observed in the soils treated with the NPK fertiliser. The combined use of the rapeseed residue and the eggshells can be beneficial to improve soil environment.     

Relationship between total concentration and dilute HCl extraction of heavy metals in sediments of harbors and coastal areas in Korea

Total concentrations of Cr, Ni, Cu, Zn, Cd and Pb in surface sediments were determined to investigate the regional trends of heavy metal contamination in 11 coastal areas in Korea. Enrichment factor (EF) of heavy metals was calculated by comparing the level of their regional background. The averages of EF values in study areas were 0.99 for Cr, 1.05 for Ni, 4.23 for Cu, 1.80 for Zn, 3.92 for Cd and 1.54 for Pb, respectively. Dilute HCl extractions were useful to deduce the anthropogenic sources of heavy metals and the 1 M HCl extractable fractions of each metal varied from 0.3 to 37.3% for Cr, 1.9 to 66.3% for Ni, 4.2 to 92.9% for Cu, 7.1 to 99.7% for Zn, 10.9 to 98.9% for Cd and 15.0 to 99.1% for Pb. Comparing 1 M HCl extractable fraction to total concentration, large portions of Cu, Zn, Cd and Pb were present as potentially bioavailable fractions from anthropogenic input and were significantly correlated with their EF values showing r > 0.68.     

Size-dependent behavior of tuna in an array of fish aggregating devices (FADs)

Several lines of evidence indicate that aggregations of yellowfin tuna associated with floating objects are more frequently composed of small animals than larger ones. Also, the diet of small yellowfin tuna caught at anchored fish aggregating devices (FADs) around Oahu, Hawaii, was found to shift quite rapidly when these fish reached approximately 50 cm FL. In order to test for ontogenetic changes in aggregation behavior, we tagged and released two distinct size classes of yellowfin tuna in an array of anchored FADs around Oahu, Hawaii. Twenty-four yellowfin tuna 30–39 cm FL and 16 yellowfin tuna 63–83 cm FL were tagged with acoustic transmitters and released near anchored FADs equipped with automated acoustic receivers. Fish in the smaller size class stayed about 2.5 times longer at individual FADs than the larger fish (mean 4.05 days vs. 1.65 days) and displayed larger horizontal movements within the array. However, the durations of unassociated phases, residence times in the entire FAD array, percentage of time spent associated with FADs and numbers of movements between FADs did not show any difference between the two size groups. The observed size-dependent behavior is discussed in terms of physiological abilities, diet segregation and anti-predator behavior.     

The selective advantage of host feminization: a case study of the green crab Carcinus maenas and the parasitic barnacle Sacculina carcini

Male crabs infected by parasitic barnacles (Rhizocephala) are known to be morphologically feminized. Here, we investigate morphological chances in green crabs, Carcinus maenas, induced by the parasitic barnacle Sacculina carcini. Infected males acquire a broader, longer and segmented abdomen, fringed with marginal setae. Copulatory appendages and pereopods are reduced in length, and the chelae become smaller. The feminization show great individual variation. Males with scars from lost externae, the parasites reproductive organ situated under the abdomen, are less modified than males carrying an externa, and the feminization is more pronounced in smaller than in larger males. No super-feminization is evident in female crabs that remain morphologically unaffected by infection. The protective value of a parasitically induced enlargement of the male abdomen may constitute an adaptation that increases parasite longevity. The additional effects on male morphology are viewed as pleiotropic side effects of the main adaptive value of enlarging the abdomen.     

A multiple instrument approach to quantifying the movement patterns and habitat use of tiger (Galeocerdo cuvier) and Galapagos sharks (Carcharhinus galapagensis) at French Frigate Shoals, Hawaii

We equipped individual tiger (Galeocerdo cuvier Péron and Lesueur, 1822) and Galapagos (Carcharhinus galapagensis Snodgrass and Heller, 1905) sharks with both acoustic and satellite transmitters to quantify their long-term movements in the Papahanaumokuakea Marine National Monument (Northwestern Hawaiian Islands). Tiger sharks exhibited two broad patterns of behavior. Some individuals were detected at French Frigate Shoals (FFS) year round, whereas others visited FFS atoll in summer to forage on fledging albatross, then swam thousands of kilometers along the Hawaiian chain, or out into open ocean to the North Pacific transition zone chlorophyll front, before returning to FFS in subsequent years. These patterns suggest tiger sharks may use cognitive maps to navigate between distant foraging areas. Different patterns of spatial behavior may arise because cognitive maps are built up through individual exploration, and each tiger shark learns a unique combination of foraging sites. Galapagos shark detections were all associated with FFS, suggesting these sharks may be more resident around oceanic islands. Both Galapagos and tiger sharks primarily used the mixed layer (<100 m depth) and made occasional deeper dives through the thermocline down to 680 m. Results show reef-associated sharks utilize a wide variety of habitats ranging from shallow atoll lagoons to deep reefs and open ocean and may provide important trophic links between these habitats.     

Bioerosion of coral reefs by two Hawaiian parrotfishes: species, size differences and fishery implications

Parrotfishes can be significant bioeroders and sediment producers on coral reefs. We quantified the bioerosion rates of two similarly sized Hawaiian parrotfishes with two different feeding modes (Scarus rubroviolaceus—a scraper and Chlorurus perspicillatus—an excavator). The results showed that feeding modes did not affect bioerosion rates but that bioerosion rates were size dependent, with largest individuals (S. rubroviolaceus 45–54 cm FL) bioeroding up to 380 ± 67 kg ind⁻¹ year⁻¹. The size for onset of bioerosion capabilities for both species was 15 cm. Grazing by the two species consumed 60% of the carbonate production of the fore reef area, suggesting that large parrotfishes in Hawaii are ecologically important bioeroders. As individual large S. rubroviolaceus contributed disproportionately more to bioerosion and sediment production than the equivalent biomass of smaller conspecifics, management strategies designed to retain normal reef bioerosion rates should seek to preserve the historical size structure of S. rubroviolaceus populations and to especially protect the larger size classes.     

Effects of cyanobacterium Microcystis aeruginosa on the filtration rate and mortality of the freshwater bivalve Corbicula leana

We compared filtering rates (FR) and mortalities between freshwater filter-feeding bivalve Corbicula leana acclimatized (AM) and non-acclimatized (NAM) to an cyanobacterial bloom (mainly Microcystis aeruginosa) over seven days. Both mussel populations were simultaneously stocked into mesocosms constructed in littoral zones of a eutrophic lake at a density of 740 ind. m(-2) for 16 days. NAMs decreased the concentration of chlorophyll-a 50% less than AMs. For the first seven days, the FRs (0.46-0.61) and mortality rate (slope = -30.2, r = -0.95) of NAMs were higher than those of AMs, possibly due to a sudden increase in unselective filtering. From the eighth day NAM mortality decreased rapidly and then stabilized, becoming similar to that of AMs through the end of the experiment. Stocking both AMs and NAMs increased the NH4-N concentration in the water, and the mortality rates of both mussel populations were correlated with NH4-N. In contrast, other nutrients and microcystin concentrations were not significantly associated with mussel mortality. These results indicate that although a sudden introduction of non-acclimatized C. leana may partially control phytoplankton biomass fora short period, previous short-term acclimatization is needed to minimize mussel mortality.     

Geochemical and microbial effects on the mobilization of arsenic in mine tailing soils

Arsenic (As) contamination has become a serious environmental problem in many countries. We have performed batch-type leaching experiments on mine tailing soils collected from three abandoned mine areas in South Korea with the objective of evaluating the effect of indigenous bacterial activity on As mobilization. The analysis of physicochemical properties and mineralogical compositions of the samples indicated that the secondary minerals or phases formed as a result of the oxidation or alteration of primary minerals were associated with the labile and bioleachable fractions of As. Compared to simulated abiotic processes using sterilization, the indigenous bacteria activated using a carbon source were able to enhance the dissolution of As under both aerobic and anaerobic conditions. The bacterial dissolution of iron (Fe) and manganese (Mn) was found to occur simultaneously with the dissolution of As, suggesting that the main bacterial mechanism was via the dissimilatory reduction of Fe(III), Mn(IV), and As(V). An anaerobic environment was more favorable for the prominent dissolution of As in the tailing soils. These results indicate that the mobilization of As can be enhanced in the oxygen-depleted part of the tailing dump, particularly with the infiltration of organic substrates. The difference in the degree of As lixiviation between the three tailing soils was found to be related to the bioavailability of As as well as the original biomass in the tailing soils.     

Anthropogenic influence on surface water quality of the Nhue and Day sub-river systems in Vietnam

In order to investigate the temporal and spatial variations of 14 physical and chemical surface water parameters in the Nhue and Day sub-river systems of Vietnam, surface water samples were taken from 43 sampling sites during the dry and rainy seasons in 2007. The results were statistically examined by Mann–Whitney U-test and hierarchical cluster analysis. The results show that water quality of the Day River was significantly improved during the rainy season while this was not the case of the Nhue River. However, the river water did not meet the Vietnamese surface water quality standards for dissolved oxygen (DO), biological oxygen demand (BOD₅), chemical oxygen demand (COD), nutrients, total coliform, and fecal coliform. This implies that the health of local communities using untreated river water for drinking purposes as well as irrigation of vegetables may be at risk. Forty-three sampling sites were grouped into four main clusters on the basis of water quality characteristics with particular reference to geographic location and land use and revealed the contamination levels from anthropogenic sources.