Estimating the abundance of banded kokopu (galaxias fasciatus gray) in small streams by nocturnal counts under spotlight illumination

The abundance of banded kokopu (Galaxias fasciatus Gray) in small streams has usually been determined by the labour intensive and invasive method of electric fishing. Recently, nocturnal counts under spotlight illumination have been used to determine presence or absence and relative abundance of banded kokopu, but the proportion of the population seen was unknown. We compared 20 spotlight counts of banded kokopu in approximately 20 m reaches in streams in the North Island, New Zealand, to population estimates determined by removal electric fishing in the same reaches. Spotlight counts were related to population estimates over a range of densities, and on average, spotlight counts were 64% of the population estimates. Though we tried to separate age-0 fish from older fish visually in the spotlight counts, the size frequency distribution of the fish caught by electric fishing showed that the visual separation was not reliable. In addition, visual counts were generally inefficient for age-0 fish (40-70 mm total length), as only about 40% were observed. Banded kokopu were also recorded in streams using time-lapse video recordings with a camera sensitive to low light levels. Diel activity showed two major peaks, one in the early morning from 0400 h to 0900 h, and the other in the afternoon and evening from 1300 h to 1900 h. Fish were less disturbed by the observer.s approach after dark than during the day, so we suggest that from dusk to about 2200 h is the best time for visual counts of banded kokopu by spotlight in summer months

Biology and potential impacts of rudd (Scardinius erythrophthalmus L.) in New Zealand

Rudd (Scardinius erythrophthalmus) is a cyprinid fish native to Europe that was illegally introduced into New Zealand in 1967. Between the 1960s and 1980s rudd were illegally spread to a number of lakes, ponds, and rivers in New Zealand, principally from the Waikato north. They now also occur in the Wanganui, Manawatu, Nelson, and Canterbury regions. Rudd undergo ontogenetic changes in diet as they grow. Young-of-the-year rudd (58–65 mm mean fork length (FL)) ate a mixture of planktonic cladocerans and chironomid pupae, and potentially competed for these foods with common smelt (Retropinna retropinna). Larger rudd (100–149 mm FL) were primarily benthivorous, and potentially competed with perch (Perca fluviatilis) of the same size, brown bullhead catfish (Ameiurus nebulosus), and probably common bullies (Gobiomorphus cotidianus). Rudd of still larger sizes were increasingly herbivorous, until at >200 mm FL their diet was >80% plant material. As rudd prefer native species of aquatic macrophytes to the introduced species, they can probably modify native plant communities and aid the invasion of introduced aquatic weeds. They may also have contributed to the switch of Hamilton Lake from a macrophyte-dominated state to a phytoplankton-dominated state. It is time for the threats posed by rudd to be recognised, and for an education campaign to be mounted. As past rudd introductions have been done outside the law, increasing the severity of penalties for further illegal transfers is unlikely to be effective, and the coarse angling community should instead be included in management decisions concerning rudd

Distribution and abundance of fish and crayfish in a Waikato stream in relation to basin area

The aim of this study was to relate the longitudinal distribution of fish and crayfish to increasing basin area and physical site characteristics in the Mangaotama Stream, Waikato region, North Island, New Zealand. Fish and crayfish were captured with two-pass removal electroshocking at 11 sites located in hill-country with pasture, native forest, and mixed land uses within the 21.6 km2 basin. Number of fish species and lineal biomass of fish increased with increasing basin area, but barriers to upstream fish migration also influenced fish distribution; only climbing and non-migratory species were present above a series of small waterfalls. Fish biomass increased in direct proportion to stream width, suggesting that fish used much of the available channel, and stream width was closely related to basin area. Conversely, the abundance of crayfish was related to the amount of edge habitat, and therefore crayfish did not increase in abundance as basin area increased. Densities of all fish species combined ranged from 17 to 459 fish 100 m-2, and biomass ranged from 14 to 206 g m-2. Eels dominated the fish assemblages, comprising 85-100% of the total biomass; longfinned eels the majority of the biomass at most sites. Despite the open access of the lower sites to introduced brown trout, native species dominated all the fish communities sampled

Macroinvertebrates and water quality: a teaching guide

Streams support a diverse community of plants and animals on or in the stream bed. These organisms comprise the benthos. Among the benthos are worms, molluscs, crustaceans, and larval insects. Insect larvae are usually the most numerous animals of the benthos. Collectively the animals of the benthos are known as benthic macroinvertebrates because of where they live, and their large size (often 10-35 mm)

Gravel galore: Impacts of clear-cut logging on salmon and their habitats

Timber harvest may have both direct and indirect effects on salmon, and with a few exceptions those effects result in lowered survival of salmon in their stream habitats compared with unlogged forest (Hicks et al. 1991b). Some impacts may be seen immediately or shortly after logging, whereas others can take decades to be expressed. Central to analyzing these effects is the context of the freshwater environment in which salmon are spawned and reared, and the life histories of the salmon species. This chapter will examine the effects of timber harvest on the freshwater habitat and life stages of salmon. It will also investigate the hypothesis that the salmon species least affected by timber harvest are those with the least reliance on stream habitats

Food webs in forest and pasture streams in the Waikato region, New Zealand: A study based on analyses of stable isotopes of carbon and nitrogen, and fish gut contents.

Stable isotopes of carbon (C) and nitrogen (N) were studied in 11 stream communities in the Waikato region of New Zealand. From comparisons of mean d13C and d15N values, food webs in the shaded, forest streams were clearly based on allochthonous material (conditioned leaf litter and terrestrial invertebrates). Autotrophs in forest streams were not a significant C source for the food webs. However, the C source of food webs in the unshaded pasture streams appeared to be a mixture of allochthonous and autochthonous material. Conditioned leaf litter appeared to contribute to the pasture stream food webs, and the d13C and d15N of some samples of epilithic diatoms indicated their consumption by invertebrates in pasture streams. Fish ate a wide range of aquatic invertebrates; longfinned eels (Anguilla dieffenbachiai) and banded kokopu (Galaxias fasciatus) also had a large proportion of terrestrial invertebrates in their diet. Filamentous green algae were found only at pasture sites, where they were sometimes abundant. The wide range of d13C values of filamentous green algae (-18.8 to -29.7[[perthousand]]) complicated understanding of their role in the stream food webs. The d13C values of Cladophora were related to water velocity, with more 13C-enriched values in pools than in runs (-23.2[[perthousand]] in pools, mean velocity 0.12 m s-1; -28.1[[perthousand]] in runs, mean velocity 0.24 m s-1). Crayfish and the gastropod mollusc Potamopyrgus appeared to be the only invertebrates to eat filamentous green algae

What Do Quarterly Workforce Dynamics Tell Us About Wal-Mart? Evidence from New Stores in Pennsylvania

In this paper I seek to better inform debate regarding Wal-Mart’s local impact on wages, and employment dynamics by combining data on Wal-Mart stores with the recently release Quarterly Workforce Indicators provided by the US Census. Use a panel of Pennsylvania counties, who saw entrance of a Wal-Mart in 2002, I find a new store has no effect on existing employee wages in the retail sector. However, new retail sector hires experience a roughly $0.50 an hour increase in total compensation in the quarter Wal-Mart enters. The entrance of a Wal- Mart draws employees from existing businesses, reducing job creation while increasing net job flows. Wal-Mart also has a longer term effect on net employment of a little more than 50 jobs in a total year. This employment finding is quite similar to findings in Hicks and Wilburn [2001] and Basker [2005]. Perhaps most importantly, Wal-Mart entrance is associated with a dramatic decline in retail sector job turnovers (over 40 percent). This result challenges much of the received wisdom of Wal-Mart’s role in the retail sector. The policy implications of these findings echo those of Ken Stone, who cautions against activist policy in support, or against Wal-Mart at the local level. Disclosure: The author of this study owns no stock in Wal-Mart or any related firm (other than that held by the mutual fund companies Vanguard and TIAA-CREF). I have performed no paid consulting services from any retail firm, its developers, local governments or related entities since 2002 (though I continue to field frequent questions on my earlier research). I have received no honoraria related to Wal-Mart research (other than travel costs paid by the Federal Reserve Bank of Richmond in 2001). In short, except for roughly$1,500 purchases of diapers annual since 1999 I have no financial relationship with Wal-Mart or any affiliate that I am aware of.Wal-Mart, Pennsylvania, Quarterly Workforce Indicators

The Impact of Wal-Mart on Local Fiscal Health: Evidence from a Panel of Ohio Counties

This research analyzes selected fiscal impacts of Wal-Mart in Ohio from 1985 through 2003. Using a panel of counties, and accounting for spatial autocorrelation in an instrumental variable model I estimate impact of Wal-Mart and Super-Centers on selected revenues and transfer payments. On revenues I find that the presence of a Wal-Mart increases local commercial property tax assessments, resulting in collection increases of between $350,000 to roughly$1.3 million. Wal-Mart also is associated with higher levels of local labor force participation. On expenditures I also find that the presence of a Wal-Mart dramatically increases the per capita EITC claims in a county (between 18 and 43 percent), while the dollar value of these claims experiences mixed impacts between Wal-Mart and a Supercenter. Similarly, the impact of Wal-Mart on Foodstamps expenditures is mixed, but small in any case. There are no in-county impacts of Wal-Mart on expenditures on Temporary Assistance to Needy Families and its predecessor Aid to Families with Dependent Children. However, Medicaid expenditures experience growth which may amount to roughly 16 additional cases per county attributable to a single Wal- Mart. The per worker costs of Medicaid estimated in this study is consistent with reported levels in a number of states, and study estimates by Dube and Jacobs [2004], Carlson [2005] and Hicks [2005a]. The magnitude and statistical certainty of these findings, accompanied by a review of previous research suggests that local fiscal intervention, either through incentives or the much touted “Wal-Mart Tax” is unwarranted.

Preliminary estimates of mass-loss rates, changes in stable isotope composition, and invertebrate colonisation of evergreen and deciduous leaves in a Waikato, New Zealand, stream.

Rates of mass loss are important in the choice of tree species used in riparian rehabilitation because leaves that break down fast should contribute to stream food-webs more rapidly than leaves that break down more slowly. To examine comparative mass-loss rates of some native evergreen and introduced deciduous trees in a New Zealand stream, fallen leaves were incubated in bags with 2 x 3 mm mesh openings. The native trees were mahoe (Melicytus ramiflorus), kahikatea (Dacrycarpus dacrydioides), silver beech (Nothofagus menziesii), rewarewa (Knightia excelsa), tawa (Beilschmiedia tawa), and the introduced trees were silver birch (Betula pendula) and alder (Alnus glutinosa). The leaf bags were left in the Mangaotama Stream for 28 days from mid April to mid May 1995 when mean water temperature was 14.5deg.C, giving a total of 406 degree days. Rates of mass loss followed the sequence: mahoe > silver birch > alder > kahikatea > silver beech > rewarewa > tawa. Mean mass-loss rate for mahoe, assuming a negative exponential model, was 0.0507 k day-1 (0.00350 k (degree day)-1), and for tawa was 0.0036 k day-1 (0.00025 k (degree day)-1). C:N ratio decreased on average from 45:1 to 35:1, and d15N increased between 0.7 and 3.0[[perthousand]] (1.8 +/- 0.41[[perthousand]], mean +/-1 standard error), excluding kahikatea. Changes in d13C were smaller and not consistent in direction. Biomass of invertebrates was greatest in bags that had lost 25-45% of their initial leaf biomass

Does Wal-Mart Cause an Increase in Anti-Poverty Program Expenditures?

As the largest private sector employer in the United States, Wal-Mart experiences considerable scrutiny over its influence on a number of regional fiscal and economic issues. These include its impact on the local retail market structure, land use patterns, local fiscal conditions and general business practices. Criticism of Wal-Mart’s business practices include, but are not limited to its anti-unionization efforts, sale of imported goods, wage and compensation structure and the use of Federal and state anti-poverty transfers by its employees. In this paper I evaluate the concerns regarding the role of Wal-Mart in changing expenditures on Federal and state anti-poverty transfers in the United States. Using a panel of the conterminous 48 states, correcting for time and spatial autocorrelation and local government mix and policy changes, I find the number of Wal-Marts, and their employment share in the retail sector have no impact on Foodstamps expenditures. Expenditures on AFDC/TANF are unaffected by Wal-Mart in the test using the number of stores to represent Wal-Mart’s presence. In the retail employment share, the impact is negative, with a 1 percent increase in Wal-Mart’s share reduced AFDC/TANF expenditures by 3.3 percent. I find that Wal-Mart does increase Medicaid expenditures by roughly $898 per worker, which is consistent with other studies of the Medicaid costs per low wage worker across the United States.