Manual Control of Phragmites australis on Pondshores of Cape Cod National Seashore, Masachusetts, USA

The non-native, invasive genotype of the common reed ( Phragmites australis (Cav.) Trin. ex Steudel) has become a problem of significant proportions throughout wetlands of North America (Saltonstall 2001). Although attempts to suppress or eradicate Phragmites have utilized a wide variety of techniques, herbicides have generally been most effective (Marks et al. 1994). In the spring, mid-summer, and late summer of 2003, we attempted to opportunistically control Phragmites in five freshwater ponds within Cape Cod National Seashore (CCNS) by repeatedly severing stems underwater, at ground level.(PDF has 4 pages.)

Nutrient Limitation of Periphyton in a Spring-Fed, Coastal Stream in Florida, USA.

There is strong evidence to suggest that ground-water nitrate concentrations have increased in recent years and further increases are expected along portions of the central Gulf coast of Florida. Much of the nitrate enriched groundwater is discharged into surface waters through numerous freshwater springs that are characteristic of the area and the potential for eutrophication of their receiving waters is a legitimate concern. To test the potential effects of elevated nutrient concentrations on the periphyton community an in situ nutrient addition experiment was conducted in the spring-fed Chassahowitzka River, FL, USA, during the summer of 1999. Plastic tubes housing arrays of glass microscope slides were suspended in the stream. Periphyton colonizing the microscope slides was subjected to artificial increases in nitrogen, phosphorus or a combination of both. Slides from each tube were collected at 3- to 4- day intervals and the periphyton communities were measured for chlorophyll concentration. The addition of approximately 10 μg/L of phosphate above ambient concentrations significantly increased the amount of periphyton on artificial substrates relative to controls; the addition of approximately 100 μg/L of nitrate above ambient concentrations did not. The findings from this experiment implicated phosphorus, rather than nitrogen, as the nutrient that potentially limits periphyton growth in this system.(PDF contains 4 pages.)

Grazing by manatees excludes both new and established wild celery transplants: Implications for restoration in Kings Bay, FL, USA

We conducted a field experiment between August 2001 and February 2002 in Kings Bay, FL, USA, designed to determine whether the amount of time allowed for wild celery (Vallisneria americana Michx) transplants to establish altered the effect of herbivorous manatees (Trichechus manatus L.)on their survival.

Estimating above-ground biomass of Melaleuca quinquenervia in Florida, USA

One hundred and thirty-eight Melaleuca quinquenervia (Cav.) S. T. Blake (broad-leaved paperbark) trees were harvested from six sites in South Florida to formulate regression equations for estimating tree above-ground dry weight.

Relationships between Larval and Juvenile Abundance of Winter-Spawned Fishes in North Carolina, USA

We analyzed the relationships between the larval and juvenile abundances of selected estuarine-dependent fishes that spawn during the winter in continental shelf waters of the U.S. Atlantic coast. Six species were included in the analysis based on their ecological and economic importance and relative abundance in available surveys: spot Leiostomus xanthurus, pinfish Lagodon rhomboides, southern flounder Paralichthys lethostigma, summer flounder Paralichthys dentatus, Atlantic croaker Micropogonias undulatus, and Atlantic menhaden Brevoortia tyrannus. Cross-correlation analysis was used to examine the relationships between the larval and juvenile abundances within species. Tests of synchrony across species were used to find similarities in recruitment dynamics for species with similar winter shelf-spawning life-history strategies. Positive correlations were found between the larval and juvenile abundances for three of the six selected species (spot, pinfish, and southern flounder). These three species have similar geographic ranges that primarily lie south of Cape Hatteras. There were no significant correlations between the larval and juvenile abundances for the other three species (summer flounder, Atlantic croaker, and Atlantic menhaden); we suggest several factors that could account for the lack of a relationship. Synchrony was found among the three southern species within both the larval and juvenile abundance time series. These results provide support for using larval ingress measures as indices of abundance for these and other species with similar geographic ranges and winter shelf-spawning life-history strategies.

Spatial distribution of Chlorpyrifos and Endosulfan in USA coastal waters and the Great Lakes

Between 1994 and 1997, 258 tissue and 178 sediment samples were analyzed for chlorpyrifos throughout the coastal United States and the Great Lakes. Subsequently, 95 of the 1997 tissue samples were reanalyzed for endosulfan. Tissue chlorpyrifos concentrations, which exceeded the 90th percentile, were found in coastal regions known to have high agricultural use rates but also strongly correlated with sites near high population. The highest concentrations of endosulfans in contrast, were generally limited to agricultural regions of the country. Detections of chlorpyrifos at several Alaskan sites suggest an atmospheric transport mechanism. Many Great Lakes sites had chlorpyrifos tissue concentrations above the 90th percentile which decreased with increasing distance from the Corn Belt region (Iowa, Indiana, Illinois, and Wisconsin) where most agriculturally applied chlorpyrifos is used. Correlation analysis suggests that fluvial discharge is the primary transport pathway on the Atlantic and Gulf of Mexico coasts for chlorpyrifos but not necessarily for endosulfans. (PDF contains 28 pages)

Análisis de los salarios de los profesores universitarios en USA (2005)

El trabajo tiene dos objetivos principales: en primer lugar,comparar los modelos universitarios de EEUU y Europa y describir las características del primero; en segundo lugar,analizar las diferencias existentes en los salarios medios en una muestra de 908 profesores universitarios en EEUU. Para la comparación de sistemas universitarios,se explican las diferencias en algunas características de todo sistema universitario,como la investigación universitaria,por ejemplo.Después, la contextualización se centra en las líneas principales del sistema universitario estadounidense,a saber, la investigación en la universidad,la financiación del sistema o la estructura del profesorado. Posteriormente, se procede a explicar los modelos del mercado de trabajo a través de teorías de la economía laboral y a realizar un análisis descriptivo de los datos en diferentes aspectos,como la categoría o la experiencia docente del profesorado. Después de estimar el modelo de regresión de los salarios medios,se obtiene que el profesorado de Research gana mayores salarios medios que el profesorado de College, por lo que el tipo de institución es relevante en las diferencias de los salarios medios. Además,el profesorado gana salarios mayores conforme adquiere más experiencia docente y mayor categoría,como se supone en la teoría del capital humano.

Análisis de los salarios de los profesores universitarios en USA (2005)

El trabajo tiene dos objetivos principales: en primer lugar,comparar los modelos universitarios de EEUU y Europa y describir las características del primero; en segundo lugar,analizar las diferencias existentes en los salarios medios en una muestra de 908 profesores universitarios en EEUU. Para la comparación de sistemas universitarios,se explican las diferencias en algunas características de todo sistema universitario,como la investigación universitaria,por ejemplo.Después, la contextualización se centra en las líneas principales del sistema universitario estadounidense,a saber, la investigación en la universidad,la financiación del sistema o la estructura del profesorado. Posteriormente, se procede a explicar los modelos del mercado de trabajo a través de teorías de la economía laboral y a realizar un análisis descriptivo de los datos en diferentes aspectos,como la categoría o la experiencia docente del profesorado. Después de estimar el modelo de regresión de los salarios medios,se obtiene que el profesorado de Research gana mayores salarios medios que el profesorado de College, por lo que el tipo de institución es relevante en las diferencias de los salarios medios. Además,el profesorado gana salarios mayores conforme adquiere más experiencia docente y mayor categoría,como se supone en la teoría del capital humano.

Salmon and freshwater fisheries in the Solway Firth. Report of the Working Party of North West Water Authority and the Annan District Salmon Fishery Board.

The Workinq Party of North West Water Authority and the Annan District Salmon Fishery Board's aims were to identify the current problems relating to the salmon and freshwater fisheries in the Solway Firth and its tributaries (embracing the catchments of the Annan, Kirtle Water, Sark, Esk, Eden, Wampool and Waver - and possibly also the Lochar Water and the Nith) to produce agreed outline solutions, and to consider the financial aspects of the future administration of these fisheries.

Sylphella puccoon gen. n., sp n. and two additional new species of aquatic oligochaetes (Lumbriculidae, Clitellata) from poorly-known lotic habitats in North Carolina (USA)

Three new species of Lumbriculidae were collected from floodplain seeps and small streams in southeastern North America. Some of these habitats are naturally acidic. Sylphella puccoon gen. n., sp. n. has prosoporous male ducts in X-XI, and spermathecae in XII-XIII. Muscular, spherical atrial ampullae and acuminate penial sheaths distinguish this monotypic new genus from other lumbriculid genera having similar arrangements of reproductive organs. Cookidrilus pocosinus sp. n. resembles its two subterranean, Palearctic congeners in the arrangement of reproductive organs, but is easily distinguished by the position of the spermathecal pores in front of the chaetae in X-XIII. Stylodrilus coreyi sp. n. differs from congeners having simple-pointed chaetae and elongate atria primarily by the structure of the male duct and the large clusters of prostate cells. Streams and wetlands of Southeastern USA have a remarkably high diversity of endemic lumbriculids, and these poorly-known invertebrates should be considered in conservation efforts.