title: Direct Effects of Microalgae and Protists on Herring (Clupea harengus) Yolk Sac Larvae.
abstract: This study investigated effects of microalgae (Rhodomonas baltica) and heterotrophic protists (Oxyrrhis marina) on the daily growth, activity, condition and feeding success of Atlantic herring (Clupea harengus) larvae from hatch, through the end of the endogenous (yolk sac) period. Yolk sac larvae were reared in the presence and absence of microplankton and, each day, groups of larvae were provided access to copepods. Larvae reared with microalgae and protists exhibited precocious (2 days earlier) and ≥ 60% increased feeding incidence on copepods compared to larvae reared in only seawater (SW). In the absence and presence of microalgae and protists, life span and growth trajectories of yolk sac larvae were similar and digestive enzyme activity (trypsin) and nutritional condition (RNA-DNA ratio) markedly declined in all larvae directly after yolk sac depletion. Thus, microplankton promoted early feeding but was not sufficient to alter life span and growth during the yolk sac phase. Given the importance of early feeding, field programs should place greater emphasis on the protozooplankton-ichthyoplankton link to better understand match-mismatch dynamics and bottom-up drivers of year class success in marine fish.
authors.affiliation: Institute of Hydrobiology and Fisheries Science, University of Hamburg, Olbersweg 24, Hamburg, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Illing
authors.affiliation: Institute of Hydrobiology and Fisheries Science, University of Hamburg, Olbersweg 24, Hamburg, Germany.
authors.forename: Marta
authors.initials: M
authors.lastname: Moyano
authors.affiliation: Institute of Hydrobiology and Fisheries Science, University of Hamburg, Olbersweg 24, Hamburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Niemax
authors.affiliation: Institute of Hydrobiology and Fisheries Science, University of Hamburg, Olbersweg 24, Hamburg, Germany.
authors.forename: Myron A
authors.initials: MA
authors.lastname: Peck
mesh_terms: D000818:Animals; D004141:Dinoflagellida / Q000472:pathogenicity*; D005399:Fishes / Q000254:growth & development* / Q000469:parasitology; D007814:Larva / Q000254:growth & development* / Q000469:parasitology; D058086:Microalgae / Q000472:pathogenicity*; D011528:Protozoan Infections / Q000469:parasitology; D013550:Swimming; D015017:Yolk Sac / Q000254:growth & development* / Q000469:parasitology