Influence of prey species and concentration on egg production efficiency and hatching success in Acartia tonsa Dana (Copepoda, Calanoida)

Abstract

We measured ingestion rate (IR), egg production rate (EPR) and egg hatching success (EHS) at increasing prey concentrations and calculated egg production efficiency (EPE) and maintenance rate (MR) in the estuarine copepod Acartia tonsa fed three different algal diets. EPR and EHS were relatively more affected by prey species than by prey concentration. EPEs were constant among carbon concentrations (C) on a diet of Rhodomonas baltica (0.202 ± 0.055, mean ± SD) and Dunaliella tertiolecta (0.034 ± 0.015), but decreased significantly from 0.371 ± 0.062 (mean of two lowest prey concentrations) to 0.200 ± 0.019 at the highest concentration of Thalassiosira weissflogii. In general it seems that other requirements than C demand limit EPE and EHS in A. tonsa. The MR (IR when EPR = 0) was significantly higher on D. tertiolecta, which also yielded the lowest EPEs, and it seems that variations in maintenance requirements may have been instrumental in evoking EPE variations as well.

Food Quantity and Quality Interactions at Phytoplankton–Zooplankton Interface: Chemical and Reproductive Responses in a Calanoid Copepod

“…It is well-established that egg production rate is higher when the food is obtained from nutrient-enriched or other optimized environments (Kleppel et al, 1998). Our results are generally in agreement with early observations which showed higher egg production rates in A. tonsa at higher food quantities (Jónasdóttir, 1994;Gusmão and McKinnon, 2009;Acheampong et al, 2011;Wendt and Thor, 2015), or at higher food qualities (lower food C:N ratios) (Kiørboe, 1989). In contrast, nonsignificant changes or a decrease in egg production rates were also found with increasing dietary C:N in A. tonsa (Jónasdóttir, 1994;Augustin and Boersma, 2006).…”

“…As food concentration increased, K C /K N increased at higher algal C:N ratios (N-deficient diets) and showed a unimodal response at lower algal C:N ratios, while K C /K P increased over the entire range of algal C:P ratios in our study (Table 3 and Figure 3). Previous studies have shown variable response patterns of GGE to increasing food concentrations in zooplankton, e.g., positive responses in the copepod Eudiaptomus graciloides (Hamburger and Boētius, 1987), Cyclops vicinus (Santer and van den Bosch, 1994) and Daphnia (Anderson et al, 2005), negative responses in A. tonsa (Kiørboe et al, 1985;Wendt and Thor, 2015), the cladoceran Penilia avirostris (Atienza et al, 2007) and the copepod Oithona davisae (Almeda et al, 2010b), and nonsignificant changes in A. tonsa (Wendt and Thor, 2015). Such variations in zooplankton GGE responses to food concentrations can be explained by differences in nutrient quality of food (e.g., algal C:N and C:P ratios in the present study; Straile, 1997;Bukovinszky et al, 2012), prey species (Wendt and Thor, 2015), development stages of zooplankton (Almeda et al, 2010a), methodological protocols (Straile, 1997), as well as withinpopulation genetic variance in the metabolic rate (Einum et al, 2019).…”

Seawater pH Predicted for the Year 2100 Affects the Metabolic Response to Feeding in Copepodites of the Arctic Copepod Calanus glacialis

“…Copepods show strong functional responses, and significant increases in both metabolic rate and RNA/DNA ratio with prey concentration are not surprising [38–40]. Such observations may provoke the conclusion that future OA effects will be masked by much stronger variations caused by natural temporal and spatial variability of prey concentrations.…”