COS 140-3 - Relationships between precipitation regime and secondary production in coastal streams

Wednesday, August 17, 2022

8:30 AM – 8:45 AM EDT

Location: 512E

Presenting Author(s)

BS

Bradley A. Strickland

Virginia Institute of Marine Science, United States

Coauthor(s)

CB

Connor Brown

University of Kansas, United States
FC

Fernando Carvallo

Texas A&M Corpus Christi, United States
CF

Christopher Frazier

University of Kansas, United States
CG

Christopher Groff

Virginia Institute of Marine Science, United States
SK

Sean Kinard

Virginia Institute of Marine Science, United States
MW

Matthew Whiles

University of Florida, United States
AU

Amber Ulseth

Sam Houston State University, United States
HV

Hannah Vander Zanden

University of Florida, United States
DH

Derek Hogan

Fisheries and Oceans Canada, Canada
CP

Christopher Patrick

Virginia Institute of Marine Science, United States

Background/Question/Methods

Precipitation is a master variable that drives stream ecosystem structure and function by controlling hydrologic variability and predictability and influencing riparian vegetation. We know little how spatial variation in rainfall drives community secondary production, a key component of energy flow. We collected macroinvertebrates and fishes in standardized reaches of nine coastal streams across a steep rainfall gradient (54 to 94 cm yr^-1) in south Texas throughout 2020. We estimated annual secondary production and biomass using appropriate methods for each taxon.

Results/Conclusions

Streams differed considerably in both annual biomass and secondary production. As expected, most (72–95%) of the production was driven by fast growing invertebrate taxa including chironomids and oligochaetes. We found that both annual fish production and annual invertebrate standing stocks declined with increasing annual rainfall. For example, fish annual production averaged 1.8 ± 1.5 (SD) g AFDM m^-2 yr^-1 across sites, and our linear model predicted an average change in 2.4 g AFDM m^-2 yr^-1 across the 40 cm yr^-1 rainfall gradient. Difference in community composition rather than species-specific shifts in turnover rates across the gradient drove the patterns we observed in production and biomass. Many stream ecosystems are vulnerable to fluctuations in hydrology, which will be altered by future shifts in precipitation patterns associated with climate change. Our work indicates that these changes in rainfall patterns may drive regime shifts and energy flow patterns of aquatic food webs.