摘要:

We collected larval northern pike (Esox lucius) in spawning wetlands and adjacent deepwater habitat during the springs of 1993 and 1994. Larval northern pike began to emigrate from spawning wetlands at sizes as small as 14.0 mm TL; however, they remained in close proximity to spawning wetlands until reaching sizes of 50 mm TL or greater. The initial emigration began before larvae became cannibalistic, and larger larvae emigrated before smaller ones indicating that intraspecific aggression probably does not play a role in this stage of emigration. Samples later in the spring indicated that some larvae either delayed emigration or returned to deeper parts of spawning wetlands. Transitional habitats may be important for survival of young of the year northern pike.

ISSN:0270-5060    

DOI:10.1080/02705060.1998.9663627

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Channel catfish (Ictalurus punctatus) were sampled from the Kansas River during October 1996 and August 1997 from Fort Riley Military Reservation and during August 1997 near Lawrence, Kansas. Fish varied in length from 100 to 506 mm at Fort Riley and from 120 to 637 mm at Lawrence. Catch per unit effort (number per net-night) was greater at Lawrence than at Fort Riley. Proportional stock density values were 23 and 48 for the Fort Riley and Lawrence samples, respectively. Individuals from both populations were in poor condition and typically had relative weight values less than 90. Age structure was similar between locations; however, approximately 44% of the channel catfish from Fort Riley were from the 1993 year class. Mean back-calculated lengths at age were significantly higher at Lawrence than Fort Riley for fish of ages 1 through 4 (P< 0.05). Incremental growth analysis on channel catfish from Fort Riley indicated that growth was fastest during 1993. Channel catfish collected near Lawrence did not exhibit the same trends in recruitment and growth. These data illustrate spatial variation in population characteristics of channel catfish in a prairie river and suggest the importance of over-bank discharge on recruitment and growth.

ISSN:0270-5060    

DOI:10.1080/02705060.1998.9663628

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We describe construction of a vacuum water filtration device for the collection of aquatic invertebrates. The unit is assembled from materials found in most laboratories and hardware stores. Its simple design allows for the extraction and filtration of aquatic invertebrates from the water column within open water as well as among submersed or emergent vegetation.

ISSN:0270-5060    

DOI:10.1080/02705060.1998.9663629

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Exposure of dewatered zebra mussels (Dreissena polymorpha) to forced (moving) air substantially increased mortality compared to that in still air. Estimated times to a 50% mortality in moving air were 32.7 h at 25°C, 4.6 h at 35°C, and 1.4 h at 45°C.

ISSN:0270-5060    

DOI:10.1080/02705060.1998.9663630

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The oligochaete,Amphichaeta americanaChen, is reported from Minnesota. This is the first record for this species in Minnesota, extending its known distribution westward. Ecological notes are given for its collection site, and the known North American distribution is summarized.

ISSN:0270-5060    

DOI:10.1080/02705060.1998.9663631

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1998.9663632

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1998.9663616

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor