摘要:

The effects of predation by three stream fishes (emerald shiner, creek chub, and mottled sculpin) on the survival and hatching success of eggs of the northern stonefly,Paragnetina media(Walker), were investigated with feeding and incubation experiments. Stonefly eggs displayed a 75% survival rate through the digestive system, but no statistically significant difference (p > 0.05) was observed in the recovery of intact eggs from the three fishes. Approximately 73% of the eggs that passed through the emerald shiners and mottled sculpins hatched within 60 days. Significantly fewer eggs (p = 0.002, 63%) hatched following passage through the creek chubs. Previous studies have shown that stonefly eggs can survive periods of freezing, desiccation, and harsh physical conditions. The present study shows that stonefly eggs can also survive passage through the digestive system of predatory stream fishes and this may represent a previously uninvestigated mechanism for localized dispersal.

ISSN:0270-5060    

DOI:10.1080/02705060.2000.9663726

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We examined microhabitat use patterns of different sizes and sexes of rusty crayfish (Orconectes rusticus) in Long Lake, Wisconsin. Crayfish were sampled using modified Louisiana “pillow” traps, identified to species, and sexed. All captured specimens were classified into one of four size classes: <35; 35–50; 50–85; >85 mm total length. We found that different members of the crayfish populations were associated with different microhabitat types and the three most important environmental variables influencing crayfish distribution were intermediate cobble sized gravel, aquatic plants, and water depth. All size classes and both sexes of rusty crayfish were most abundant within fine grain soft bottom substrate (detritus or sand).

ISSN:0270-5060    

DOI:10.1080/02705060.2000.9663727

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Airborne video cameras equipped with narrow band filters were used to assess chlorophyll-a concentration in flood retention reservoirs of the Little Washita River watershed in Oklahoma. The video data was analyzed in three steps: raw data, data after calibration, and reflectance data. Results indicate that airborne video imaging of reservoirs has a great deal of potential and may have far-reaching effects in lake management strategies.

ISSN:0270-5060    

DOI:10.1080/02705060.2000.9663728

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.2000.9663729

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.2000.9663715

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor