Inland dispersal of adult aquatic insects

1. Adult caddisflies (Trichoptera) and mayflies (Ephemeroptera) were light-trapped on summer evenings along the Detroit River and Lake St. Clair, near Windsor, Ontario, Canada. Light traps were located at the shore and at increasing distances inland up to 5 km, and were operated simultaneously for 2 h following sunset. Catches of five species of caddisflies of the family Hydropsychidae ( Cheumatopsyche campyla , Cheumatopsyche speciosa , Hydropsyche hageni , Hydropsyche phalerata , Macrostemum zebratum ) and the mayfly Hexagenia (Ephemeridae) were used to examine inland distribution.
2. Inland dispersal was limited: catches of caddisflies declined at a greater than exponential rate with increasing distance from shore. Mean dispersal distance from the shoreline ranged from 650 to 1845 m. Smaller caddisfly species dispersed shorter distances than larger caddisflies and Hexagenia .
3. Inland distribution of adult caddisflies exhibited considerable interspecific variation: distribution was inconsistent among trials for Hexagenia , possibly owing to timing of collections in relation to periods of peak emergence.
4. Sex ratios of caddisflies were female biased at most sites. No consistent bias was observed for Hexagenia . Different inland distribution patterns were observed for males and females. The differences appeared to reflect species-specific reproductive strategies.     

Evidence for an H-Y Crossreactive Antigen in Invertebrates

A sex specific antigen which crossreacts with the mammalian H-Y antigen has been identified on the cell surface of hemocytes from the lobster ( Homarus americanus ) and the gonadal cells of three insect species. The hemocytes from the male lobster, the testicular cells from the male beetle ( P. cornutus ), and the ovarian cells from two Orthopteran species ( L. maderae and D. punctata ) specifically absorbed H-Y antibodies. The specificity of H-Y antibody absorptions by cells from only one sex, suggest that an ancestral H-Y-like antigen may be present in invertebrates which could be engaged in sexual (cellular) recognition events.     

Studies on death of deteriorated barley seeds in soil

Seeds of barley cv. Golden Promise which had been deteriorated by storing at 20% moisture content and 30 °C and which all had viabilities >85% were treated with a slurry of calcium peroxide and with dusts of a mercurial and a non-mercurial fungicide. Calcium peroxide improved seedling emergence in wet soil conditions and deteriorated seeds benefited more than non-deteriorated seeds. The fungicide dusts had no effects. In controlled conditions at 20 °C, deteriorated seeds in wet soil died mainly within 2 days of sowing and they were more tolerant if they were placed in moist soil for 2 days before transfer to wet soil. Application of a mercurial fungicide and sterilizing the soil and the surface of seeds improved emergence but did not restore it to the level in moist soil. Fusarium culmorum, F. equiseti, Mucor spp. and Mortierella spp. dominated the fungus flora isolated from surface sterilised dead seeds in wet soil. When the fungi were inoculated to seeds, they increased the proportion which died in wet soil but only at high inoculum levels. It was concluded that they acted primarily as saprophytes depriving seeds of oxygen and secondarily as seed colonisers.     

Effects of chronic chlorine exposure on litter processing in outdoor experimental streams

SUMMARY 1. The effects of chlorine on litter ( Potamogeton crispus L.) processing were examined using six outdoor experimental streams. Downstream portions of two streams were dosed at c . 10 μg l⁻¹ Total Residual Chlorine (TRC), one stream at 64 μgl¹, and one stream at 230μg l⁻¹. Two control streams were not dosed; upstream riffles of each stream served as instream controls.
2. Two 35 day litter breakdown (per cent AFDW remaining) experiments indicated significantly lower decay rates in the high dose riffle. No other concentration of chlorine significantly affected decay rate.
3. A third experiment, conducted in medium and high dose streams, indicated that high dose chlorine exposure reduced litter decomposition rates significantly, and reduced microbial colonization, microbial electron transport system activity, and microbial litter decomposition after 4 days but not after 11 days of exposure. The number of amphipod shredders colonizing litter bags was also reduced significantly with high chlorine dose.
4. A fourth experiment, after dosing was terminated, provided direct evidence that amphipod shredders were important in facilitating litter decomposition: litter bags stocked with amphipods had significantly higher decomposition rates than bags which excluded shredders.
5. Overall results indicate that the high dose (c. 230 μgl⁻¹ TRC) of chlorine reduced litter processing rates partly by reducing initial microbial conditioning, but primarily by reducing the colonization of amphipod shredders.     

Effects of hollow heart on growth of peas

Hollow heart of pea seed (Pisum sativum L.) delayed germination and reduced seedling growth. Plants from seeds with the disorder were smaller and yielded less than those from normal seeds. Affected cells were dead, but immobilization of starch reserves within them could not wholly account for the reduced growth and evidence suggested the presence of a germination and growth inhibitor.     

Isolation and cross‐familial amplification of 41 microsatellites for the brook charr (Salvelinus fontinalis)

The brook charr (Salvelinus fontinalis; Osteichthyes: Salmonidae) is a phenotypically diverse fish species inhabiting much of North America. But relatively few genetic diagnostic resources are available for this fish species. We isolated 41 microsatellites from S. fontinalis polymorphic in one or more species of salmonid fish. Thirty‐seven were polymorphic in brook charr, 15 in the congener Arctic charr (Salvelinus alpinus) and 14 in the lake charr (Salvelinus namaycush). Polymorphism was also relatively high in Oncorhynchus, where 21 loci were polymorphic in rainbow trout (Oncorhynchus mykiss) and 16 in cutthroat trout (Oncorhynchus clarkii) but only seven and four microsatellite loci were polymorphic in the more distantly related lake whitefish (Coregonus clupeaformis) and Atlantic salmon (Salmo salar), respectively. One duplicated locus (Sfo228Lav) was polymorphic at both duplicates in S. fontinalis.