ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665086

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Seasonal and diel drift of fish were studied in the fifth order of the Illinois River, Arkansas during 1980–1982 to assess the inclination of the various species (ca. 60) in the community (and size groups within species) to drift and to determine their diel and seasonal periodicities of drift. Eighteen taxa were identified from the drift. Channel catfish (Ictalurus punctatus) and flathead catfish (Pylodictus olivaris) alevins represented 57% and 12% of the drift respectively. Slender madtom catfish (Noturus exilis) were abundant in the riffle studied but none were collected in the drift. Larval fish drifted from late April through late August with a peak on 23–24 June when an estimated 37,203 drifted through the study area. A distinct diel pattern was observed with peaks at 2300 and 0300 hours. Drifting larvae were more abundant near the surface and margins with catfish alevins on the deep side and cyprinids, sunfishes, and all prolarvae on the shallow side of the stream. Post-larval development (absorption of yolk sacs) had been attained by 91% of the fish captured in drift nets. This study did not support the idea that all lotic organisms drift at some time during their life history since several species which were abundant or common in the reach were absent or rare in the drift.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665087

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Mayfly community structures in a thermally-stressed, previously thermally-stressed and an undisturbed stream were compared based on nymphal colonization of leaf packs incubated over a 48 d period from December 1982 to February 1983. Temperatures ranged from 7–31C in the thermally-stressed stream and from 4–12C in the other two streams. Accumulated degree days (>0C) were 734, 340 and 322 for the thermally-stressed, post-stressed and undisturbed streams, respectively.Stenonemaspp. numerically dominated the mayfly fauna over the sampling period in the undisturbed (70%) and post-stressed (98%) streams, but was replaced byCaenis diminutaWalker (88%) in the stream receiving thermal effluent from a nuclear production reactor.Caenis diminutais tolerant of rapidly fluctuating (Delta;T > 11C/hr) and high temperatures (possibly up to 40C).

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665088

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Invertebrate colonization on newly introduced rock substrates was examined from July through October 1982 in the tailwater of Barren River Lake, Kentucky. Chironomidae, the dominant taxon of benthic insects, reached full colonization by day 14. Colonization by Oligochaeta, the other major invertebrate taxon, was not completed by the end of the 95-day period of observation. It may have been delayed because insufficient food (periphyton and detritus) had accumulated on the clean rocks. Rapid recolonization of dewatered substrates may be especially critical for maintaining adequate fish food in tailwaters of flood-control reservoirs.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665089

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Stevens Brook wetland is presently receiving partially treated sewage from the City of St. Albans, Vermont. The water quality in St. Albans Bay is deteriorating. There is conflicting evidence for the theory that wetlands act as a nutrient sink or as a biotic nutrient filter. This research is an investigation into the productivity and trophic food chain relationships of Stevens Brook wetland. We compared this to a non-impacted area, Scomotion Creek wetland in Plattsburgh, New York. Temperature, pH, dissolved oxygen, transparency, alkalinity, conductivity, sodium, potassium, calcium, magnisium, nitrate, total phosphorus, bacteria, phytoplankton, aquatic macrophytes, and benthic invertebrates were sampled in both wetlands. The data Indicate that excessive nutrients and a large carbon source result in high phytoplankton productivity and bacterial growth. This coupled with particulate matter causes low transparency and thus a decrease in submergent vegetation and a decrease in invertebrate faunal diversity. Increased production is not converted to additional biomass of consumers but is exported to the downstream water body. Thus, Stevens Brook wetland appears to be a pass-through system rather than a storage system, and is not effective in tertiary treatment of sewage effluent.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665090

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The phytoplankton, zooplankton, and the macroinvertebrate snag communities of Black Creek, South Carolina, upstream and downstream of an impoundment were Investigated during 1982. Phytoplankton and zooplankton densities upstream of the impoundment were very low. The reservoir outflow contributed a large part of the zooplankton of all sizes to the stream immediately below the impoundment. Large copepods and cladocerans were almost absent from the community 2.2 km downstream leaving mainly nauplii, small cladocerans, and rotifers. The reservoir also released a moderate amount of phytoplankton into the stream which was only slightly reduced further downstream.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665091

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The surface area of submersed macrophytes is often viewed from different perspectives such as substrate for colonization by periphyton, or protective cover for fishes. Consequently, several different methods have been used to measure it. We describe a method for measuring that area with an electronic surface area meter, a device that yields, for large samples of macrophytes, measurements in units of square meters of plant surface area per square meter of bottom. Unpreserved macrophytes, pressed gently between plastic sheets, are passed through the sensing head of the meter, which electronically scans and measures their surface area. The technique is several times faster and more precise than previous methods even for plants with finely dissected leaves.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665092

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Greater numbers of taxa and numbers of organisms occurred in the watermilfoil habitat as compared with the open littoral zone, however, the differences were generally not significant. Community structure, as measured by a similarity index, was significantly different between the two habitats. When the number of organisms per square meter of substrate was compared, there were no significant differences between the two habitats.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665093

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The distribution patterns and food habits of young-of-the-year (YOY) fishes in a lentic area adjacent to the main channel of pool 7 of the upper Mississippi River were studied. Habitats sampled grouped distinctly based on percent composition and abundance of YOY fishes with those having submergent vegetation dominated by a number of important sport species. In late spring, the grouping of stations depended on the presence or absence of newly transformed northern pike (Esox lucius). In early summer, stations did not differ as distinctly in composition, but in total abundance of young. Those stations with submergent vegetation had total catches which were more than double those elsewhere. By late summer, submergent and mixed vegetation stations formed a distinct assemblage influenced by the preponderance of three species of sunfishes. Their diets suggested that species inhabiting areas of submergent vegetation were very flexible in their choice of food resources. Black crappie (Pomoxis nigromaculatus), rock bass (Ambloplites rupestris), and bluegill (Lepomis macrochirus) fed on similarly sized items. Increased sedimentation or deposition of dredged material in backwaters may adversely and severely affect recruitment of several sport fish species by reducing or removing critical beds of submergent vegetation.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665094

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The temporal spawning distributions and certain aspects of the early life-histories of bluegill (Lepomis macrochirus) and redear sunfish (L. microlophus) were compared in a recently stocked 0.6-ha pond in central illinois. Redear sunfish spawned earlier, at lower temperatures, and for a shorter interval than did bluegill. Age-0 redear sunfish were primarily restricted to littoral habitats; in contrast, age-0 bluegill occupied both limnetic and littoral habitats, but they became increasingly restricted to littoral habitats as their size increased. First-summer growth rates of early-spawned individuals of the two species were similar, but late-spawned redear sunfish grew significantly slower than similarly-aged bluegill. However, because redear sunfish spawned earlier, in September their young were generally larger ([Xbar]TL= 39.0 mm) than bluegill young ([Xbar]TL= 25.8 mm). Age-0 bluegill were much more abundant than age-0 redear sunfish in September (57 to 1). Inconsistent reproductive success is implicated as a factor limiting recruitment in redear sunfish populations.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665095

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor