Publications

@article{Stancheva2019,

title = {First record of the rare freshwater alga Tetrasporopsis fuscescens (Chrysomerophyceae, Ochrophyta) in North America},

author = {R Stancheva and P Škaloud and M Pusztai and CL Loflen and RG Sheath},

url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/fottea_fot-201902-0006.pdf},

doi = {10.5507/fot.2019.007},

year  = {2019},

date = {2019-10-30},

urldate = {2019-10-30},

journal = {Fottea},

volume = {19},

issue = {2},

pages = {163-174},

abstract = {This study presents the first record of the ochrophyte alga Tetrasporopsis fuscescens in North America, confirmed with light and transmission electron microscopic photomicrographs, cytochemical and molecular phylogenetic analyses. T. fuscescens was recorded rarely, being found in the benthos of only twelve stream sites: nine locations in Southern California and three in Northern California. More than half of the streams were non-perennial, characterized by long dry periods. Tetrasporopsis cells were gold-colored, spherical, with a distinct wall, assembled in the periphery of macroscopical gelatinous colonies, which start as tubular or sac-like structures, but later become membranous. The cells have 1-2 parietal chloroplasts, without a stigma or pyrenoid, and reproduction occurs by longitudinal cell division. Other features of the genus are as follows: cells in the colonies also divide by what appears to be smaller autospores with remnant cell walls remaining, the colonial mucilage consists of cylindrical dichotomously branched tubes radiating from the center of the colony to which attach the peripheral cells, and older cells become filled with large oil droplets. A combined gene tree of sequences from nuclear SSU rDNA, plastid rbcL, psaA, psbA and psbC showed that T. fuscescens specimens from Europe and U. S. A. formed a clade, which clustered with taxa classified in the class Chrysomerophyceae.},

keywords = {algae, freshwater, freshwater ecosystem},

pubstate = {published},

tppubtype = {article}

}

@article{Wehr2017,

title = {How important are terrestrial organic carbon inputs for secondary production in freshwater ecosystems?},

author = {Michael T. Brett and Stuart E. Bunn and Sudeep Chandra and Aaron W. E. Galloway and Fen Guo and Martin J. Kainz and Paula Kankaala and Danny C. P. Lau and Timothy P. Moulton and Mary E. Power and Joseph B. Rasmussen and Sami J. Taipale and James H. Thorp and John D. Wehr},

doi = {https://doi.org/10.1111/fwb.12909},

year  = {2017},

date = {2017-01-19},

journal = {Freshwater Biology},

volume = {62},

number = {5},

pages = {833-853},

abstract = {Many freshwater systems receive substantial inputs of terrestrial organic matter. Terrestrially derived dissolved organic carbon (t‐DOC) inputs can modify light availability, the spatial distribution of primary production, heat, and oxygen in aquatic systems, as well as inorganic nutrient bioavailability. It is also well‐established that some terrestrial inputs (such as invertebrates and fruits) provide high‐quality food resources for consumers in some systems. 

In small to moderate‐sized streams, leaf litter inputs average approximately three times greater than the autochthonous production. Conversely, in oligo/mesotrophic lakes algal production is typically five times greater than the available flux of allochthonous basal resources. 

Terrestrial particulate organic carbon (t‐POC) inputs to lakes and rivers are comprised of 80%–90% biochemically recalcitrant lignocellulose, which is highly resistant to enzymatic breakdown by animal consumers. Further, t‐POC and heterotrophic bacteria lack essential biochemical compounds that are critical for rapid growth and reproduction in aquatic invertebrates and fishes. Several studies have directly shown that these resources have very low food quality for herbivorous zooplankton and benthic invertebrates. 

Much of the nitrogen assimilated by stream consumers is probably of algal origin, even in systems where there appears to be a significant terrestrial carbon contribution. Amino acid stable isotope analyses for large river food webs indicate that most upper trophic level essential amino acids are derived from algae. Similarly, profiles of essential fatty acids in consumers show a strong dependence on the algal food resources. 

Primary production to respiration ratios are not a meaningful index to assess consumer allochthony because respiration represents an oxidised carbon flux that cannot be utilised by animal consumers. Rather, the relative importance of allochthonous subsidies for upper trophic level production should be addressed by considering the rates at which terrestrial and autochthonous resources are consumed and the growth efficiency supported by this food. 

Ultimately, the biochemical composition of a particular basal resource, and not just its quantity or origin, determines how readily this material is incorporated into upper trophic level consumers. Because of its highly favourable biochemical composition and greater availability, we conclude that microalgal production supports most animal production in freshwater ecosystems.},

keywords = {allochthonous, autochthonous, biochemical composition, freshwater, resource utilisation},

pubstate = {published},

tppubtype = {article}

}