Identification of larval Pacific lampreys (Lampetra tridentata) , river lampreys (L. ayresi) , and western brook lampreys (L. richardsoni) and thermal requirements of early life history stages of lampreys. Annual report 2002

Meeuwig, M.H.; Bayer, J.M.; Seelye, J.G.; Reiche, R.A.

BPA Report DOE BP 00004695-2: Unpaginated

2003


Accession: 022798729

Download citation:  
Text
  |  
BibTeX
  |  
RIS

Article/Abstract emailed within 1 workday
Payments are secure & encrypted
Powered by Stripe
Powered by PayPal

Abstract
Two fundamental aspects of lamprey biology were examined to provide tools for population assessment and determination of critical habitat needs of Columbia River Basin lampreys (the Pacific lamprey, Lampetra tridentata, and the western brook lamprey, L. richardsoni). In particular: 1) we examined the usefulness of current diagnostic characteristics in identification of larval lampreys, specifically pigmentation patterns, and collected material for development of meristic and morphometric descriptions of early life stages of lampreys, and 2) we examined the effects of temperature on survival and development of early life stages of Columbia River Basin lampreys. In 1999 thirty-one larval lampreys (ammocoetes) were collected from locations throughout the Columbia River Basin and transported to the Columbia River Research Laboratory. They are being examined and identified to species at approximately sixweek intervals until they metamorphose and their identity can be confirmed by dentition patterns. Currently, these lampreys have been sampled 21 times, and two individuals have metamorphosed allowing confirmation of species identification. Of the lampreys that have not metamorphosed, only one has been inconsistently identified (Pacific lamprey in 83% of the sampling events and western brook lamprey in 17% of the sampling events), suggesting that pigmentation patterns do not change appreciably through time. In 2001 and 2002 we artificially spawned Pacific and western brook lampreys in the laboratory to provide material for meristic and morphometric descriptions. We have collected, digitized, preserved, and measured the mean chorion diameter of 320 fertilized Pacific lamprey eggs and 280 fertilized western brook lamprey eggs. Pacific lamprey eggs were significantly larger than western brook lamprey eggs (t = 32.758, df = 528.62, P < 0.0001) with a mean difference of 0.231 mm. We have collected, digitized, and preserved 156 Pacific lamprey larvae (standard length: 7.20 - 31.79 mm) and 146 western brook lamprey larvae (standard length: 6.64 - 25.90 mm). For morphometric descriptions of these individuals we have selected eight homologous landmarks that define a two-cell truss network with two appended triangles. Truss element lengths have been summarized based on the original measurement scale and on a scale proportional to each individual's standard length. In 2001 and 2002 Pacific and western brook lampreys were artificially spawned and resulting progeny were reared at the Columbia River Research Laboratory at 10° C, 14° C, 18° C, and 22° C. Temperature significantly affected survival of early life stage Columbia River Basin lampreys (F 3, 124 = 208.42, P < 0.0001) with a significant decrease in survival at 22° C when compared to other rearing temperatures. A significant difference in survival over the course of the experiment was observed between Pacific (83.8%) and western brook (84.8%) lampreys (F 1, 124 = 6.20, P = 0.0141); however, the biological significance of this difference is questionable. A significant difference in survival between the time of 50% hatch and the time of 50% yolk assimilation was also observed (F 1, 125 = 81.46, P <0 .0001). Temperature significantly affected the occurrence of larval abnormalities at 50% yolk assimilation (F 3, 111 = 130.49, P < 0.0001) with a greater percentage of abnormalities occurring at 22° C than at other rearing temperatures.