Can bacterivory alone sustain larval development in the polychaete Hydroides elegans and the barnacle Balanus amphitrite?

Abstract

Although recent studies have found that some invertebrate larvae can meet part of their metabolic needs through bacterivory, it is unclear to what extent bacterivory can compensate for reduced phytoplankton abundance. The present study determined whether larvae of a polychaete (Hydroides elegans) and a barnacle (Balanus amphitrite) can survive, grow, and develop to competence solely on a diet of bacteria. In laboratory experiments, H. eleganslarvae provided with bacteria as their sole particulate food source completed larval development, attached, and metamorphosed into healthy early juveniles. In addition, several of these juveniles, when provided with phytoplankton after metamorphosis, developed to maturity and spawned viable offspring. Bacterial abundances measured in Port Shelter, a bay in Hong Kong waters where organisms for the present study were collected, would not sustain maximum development rates of H. elegans larvae. However, bacterial abundances were sufficiently high and cons~stent over time to constitute a reliable food source. Consequently, starvation may not be a direct cause of larval mortality in this species. On the other hand. B. amphitritelarvae provided ~71th bacteria did not grow, and death occurred at the same age as in starved larvae, suggesting they cannot use bacteria as a supplementary food source. Available data suggests that most barnacle recruitment in Hong Kong waters occurs when phytoplankton abundance reaches peak levels. Recruitment of H. elegans, however, occurs throughout the year, suggesting that spawning and successful larval development may be independent of phytoplankton availability, and that larvae largely rely on alternate food sources such as bacteria.

Heterochronic Developmental Shift Caused by Thyroid Hormone in Larval Sand Dollars and Its Implications for Phenotypic Plasticity and the Evolution of Nonfeeding Development

“…However, a reduced larval period could lead to a reduced juvenile size (or a reduction in stored energy, as discussed above), which might have negative fitness consequences. Although such fitness consequences have been previously discussed (Strathmann 1974(Strathmann , 1977Kolding and Fenchel 1981;Perron 1986;Emlet et al 1987;Pechenik et al 1998), experimental tests are relatively rare (but see Emlet and Hoegh-Guldberg 1997;Gosselin and Qian 1997). Our results demonstrate for the first time that metamorphosis at a substantially reduced juvenile size is mechanistically possible in planktotrophic echinoid larvae (for data on lecithotrophic larvae see Okazaki and Dan 1954;Emlet and HoeghGuldberg 1997).…”

Coliform accumulation in Amphibalanus amphitrite (Darwin, 1854) (Cirripedia) and its use as an organic pollution bioindicator in the estuarine area of Recife, Pernambuco, Brazil

“…Amphibalanus amphitrite is more microphagous in nature and is capable of feeding on phytoplankton and debris (Desai and Anil, 2004). Regarding the nutrition of this species' larvae, Gosselin and Qian (1997) observed that when bacteria concentrations were added, barnacle larvae did not grow and did not accumulate particulate material in their gut, which suggests that A. amphitrite larvae are unable to capture bacteria.…”

Contribution of dietary bacteria to metal accumulation in the slipper limpet

“…Data in parentheses are the standard deviations of 10 replicate measurements. Bacteria strain numbers correspond to the strains and properties described in Gosselin & Qian (1997) percentage of radioactivity retained in the slipper limpets, which is defined as the AE of the metals, k is the depuration rate constant, and t is time of depuration. This model assumes a 2-compartment depuration pattern for ingested metal, with the first compartment representing the digestive and assimilative process, and the second compartment representing the physiological turnover of metals.…”

“…AE and k u were determined in this study (Table 3). The mean K d values for phytoplankton were taken from Fisher & Reinfelder (1995), whereas (Gosselin & Qian 1997), and the typical seston concentration is about 1 mg l -1 (Chiu et al 1994). In modeling, we therefore used 2 × 10 6 cells ml -1 and 1 mg l -1 as representative bacterial and seston concentrations for Hong Kong waters.…”

“…Bacteria are an important component of the microbial loop (Azam et al 1983). A variety of aquatic animals, common or dominant in their communities, have been shown to effectively capture bacteria in addition to other planktonic food (e.g., acleractinian coral, Bak et al 1998; reef sponges, Reiswig 1974, Pile 1997; polychaete larvae and juveniles, Gosselin & Qian 1997mussels, Seiderer & Newell 1985, Langdon & Newell 1990, Kreeger & Newell 1996 clams, Decho & Luoma 1991; oyster larvae and adults, Langdon & Newell 1990, Douillet 1993, Douillet & Langdon 1993; asteroid larvae, Rivkin et al 1986;and ascidians, Bak et al 1998). These studies have pointed out the significance of bacteria as a carbon source for the animal nutrition.…”