Feeding dynamics of larval Pacific herring (Clupea pallasi) on natural prey assemblages: the importance of protists

Abstract

The role of protists in the diet of larval Pacific herring (Clupea pallasi) was examined using a natural assemblage of microplankton (10-200 µm) in laboratory incubations in May and June of 2008. Available prey consisted of protists (diatoms, dinoflagellates, aloricate ciliates, and loricate ciliates) and metazoans (trochophores, bivalve larvae, rotifers, copepod nauplii, and gastropod larvae). We used a prey enumeration technique that included soft-bodied heterotrophic protists (aloricate ciliates and athecate dinoflagellates) in the diet. We observed significant consumption of aloricate ciliates, loricate ciliates, bivalve larvae, dinoflagellates, and 73-200 µm available prey. Clearance rates (ml larva -1 h -1 ) were used as a measure of prey selectivity. The herring larvae showed strong selection for bivalve larvae and 73-200 µm available prey. Protists were selected for at rates comparable to metazoans. Ingestion rates (µg C larva -1 h -1 ) showed that the majority of larval carbon intake was from diatoms and aloricate ciliates. The results of this study illustrate that there is a direct trophic link between larval iv herring and the microbial loop, and protists may comprise a substantial portion of the larval fish diet, possibly alleviating food limitation.

Recruitment decline in North Sea herring is accompanied by reduced larval growth rates

“…However, these analyses typically examined the entire plankton community as a whole and as a consequence may have placed emphasis on changes that are not relevant to herring, or overlooked changes that are. For example, the importance of micro-zooplankton in the diets of larvae has received little attention (Montagnes et al 2010) even though some studies indicate this fraction of the plankton community may be important in the diets of herring larvae (de Figueiredo et al 2005, Friedenberg et al 2012. Unfortunately there are no detailed studies specifically targeting the western and central North Sea which would indicate whether this portion of the plankton community has changed in abundance through the various planktonic regime shifts.…”

Zooplankton of tidal marsh channels in relation to environmental variables in the upper San Francisco Estuary

“…m −3 reported by Bollens et al (2011) for open waters of the SFE (note that both studies used the same collection techniques). Protists such as tintinnid ciliates can be important sources of food for larval fishes, both directly (Bollens & Sanders 2004, Friedenberg et al 2012) and indirectly via the microbial food web (Gifford et al 2007, RollwagenBollens et al 2011). Although we do not know whether the difference in tintinnid ciliate abundance between our study is due to interannual or habitat-specific differences, the low number of tintinnids present in marshes during our study may have implications for feeding and growth of young fish and other consumers, as well as cycling of material and energy in the estuary more generally.…”

Exploring the microzooplankton–ichthyoplankton link: a combined field and modeling study of Atlantic herring (Clupea harengus) in the Irish Sea

“…Using in situ plankton abundance, IBM-based (simulated) growth rates of larvae tended to be lower than most (but not all) of the observed growth rates of 15-to 18-mm larvae at each station and in both years. In smaller (7-to 14-mm SL) larvae, where microzooplankton is thought to play a major role in the diet (Friedenberg et al, 2012), the IBM drastically underpredicted in situ growth rates. The model predicted that larvae would not grow at some stations (Station 1 in 2012 andStations 14, 15, 16 and19 in 2013) where in situ (biochemical-based) growth rates were positive.…”

“…Microzooplankton such as protists and early life stages of copepods play an important role as grazers of bacteria and flagellates (Fenchel, 1988;Calbet and Saiz, 2005) and as prey for higher trophic levels (e.g. copepods, larval fish) (Montagnes et al, 2010b;Friedenberg et al, 2012). The role of microzooplankton as prey may be particularly important during time periods characterized by low rates of primary production.…”

“…For these reasons, the microzooplankton-ichthyoplankton link has been examined most frequently in laboratory experiments using, for example, prey depletion experiments (Friedenberg et al, 2012), prey labelled with fluorescent microspheres (Lessard et al, 1996;Nagano et al, 2000) or by measuring lipid biomarkers (Rossi, 2006) or biochemical condition (Overton et al, 2010;Illing et al, 2015) of the larvae. The results of various laboratory studies suggested that protists can partially or completely fulfil the daily nutritional and energy requirements of the larvae of Atlantic cod (Gadus morhua) ( Van der Meeren, 1991;Hunt von Herbing and Gallager, 2000), northern anchovy (Engraulis mordax) (Ohman et al, 1991), Pacific herring (Clupea pallasi) (Fukami et al, 1999;Friedenberg et al, 2012) and Atlantic herring (Illing et al, 2015).…”