Responses of European anchovy vital rates and population growth to environmental fluctuations: An individual-based modeling approach

Abstract

A size-structured, bioenergetics model was implemented to examine the effects of short-term environmental changes on European anchovy, Engraulis encrasicolus, in the Northwestern Mediterranean Sea. The model approach was based on Dynamic Energy Budget (DEB) theory and details the acquisition and allocation of energy (J d −1) during an organisms' full life-cycle. Model calibration was achieved using biometric data collected from the Gulf of Lions between 2002 and 2011. Bioenergetics simulations successfully captured ontogenetic and seasonal growth patterns, including active growth in spring/summer, loss of mass in autumn/winter and the timing and amplitude of multi-batch spawning events. Scenario analysis determined that vital rates (growth and fecundity) were highly sensitive to short-term environmental changes. The DEB model provided a robust foundation for the implementation of an individual-based population model (IBM) in which we used to test the responses of intrinsic and density-independent population growth rates (r) to observed and projected environmental variability. IBM projections estimate that r could be reduced by as much as 15% (relative to that estimated under mean conditions) due to either a 5% (0.8 °C) drop in temperature (due to a reduced spawning duration), a 18% (25 mg zooplankton m −3) depletion in food supply, a 30% increase in egg mortality rates, or with the phytoplankton bloom peaking 5 weeks earlier (in late-February/Winter). The sensitivity of r to short-term (1 year) and long-term (4-10 year) environmental changes were similar, highlighting the importance of first-year spawners. In its current form, the models presented here could be incorporated into spatially-explicit, higher-trophic (predatorprey and end-to-end ecosystem), larval-dispersal and toxicokinetic models or adapted to other shortlived foraging fish (clupeid) species. Highlights ► IBM implemented for European anchovy, an important ecological and economical species. ► Mean ontogenetic and seasonal growth and fecundity patterns were accurately captured. ► High variation in anchovy vital rates can be explained by the model. ► Population growth rate (r) sensitivity to climate scenarios are quantified. ► A 0.8 °C drop in temperature could cause a 15% decline in r.

Relationships between feeding, growth and swimming activity of European sprat (Sprattus sprattus L.) post-larvae in the laboratory

“…Very few measurements of the relationship between feeding and growth have been made for clupeids (e.g., De Silva and Balbontin 1974;Kiørboe et al 1987;Opaliński et al 2004) and work on larvae or post-larvae (very young juveniles) is particularly rare (e.g., Houde and Schekter 1981;Checkley 1984;Kiørboe and Munk 1986) as reviewed by Peck et al (2013). The scarcity of data is surprising given the trophodynamic importance of these small pelagic fish within many aquatic systems and the ongoing efforts to build bioenergetic models to predict their feeding and/or growth (Pikitch et al 2012;Pethybridge et al 2013).…”

Temporal and inter-specific variations in forage fish feeding conditions in the NW Mediterranean: lipid content and fatty acid compositional changes

“…Our findings thus suggest that (1) forage fishes sampled in this study fed close to the coast, and/or (2) the maximum chlorophyll concentrations, and thus the onset of vertical stratification of the water column which supports phytoplankton productivity, may have come later in 2010 than in previous years. Time-series data of satellite derived seasurface chlorophyll concentrations in 2010 supports the latter hypothesis of temporal changes in surface productivity (Pethybridge et al 2013a). …”

“…Owing to the resulting bottom-up and top-down (wasp-waist ecosystem) constraints, in addition to fishing pressures and an r-strategy life-history, the population dyn a mics of mid-trophic fishes are subject to considerable fluctuations caused by environmental variability (Lloret et al 2004, Santojanni et al 2006, Engelhard et al 2014). The close relationship between food supply, individual performance and population dynamics of forage fishes (Daskalov 2002, Pikitch et al 2012, Pethybridge et al 2013a) emphasizes the need to better understand their feeding ecology, including prey availability (quality and quantity). Furthermore, the importance of forage fishes to top-order predators and humans necessitates that information on their nutritive and energetic quality is understood and reported.…”

210 Po and 210 Pb trophic transfer within the phytoplankton–zooplankton–anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea)

“…Since 210 Po seems associated with protein in animal tissues (Carvalho and Fowler, 1994;Durand et al, 1999), then the lower lipid content of anchovy compared to that of sardine may explain higher 210 Po concentrations. We suggest that different energetic strategies could influence the bioaccumulation of contaminants in sardine and anchovy and that emphasis should be made in the future on the relationships between energy transfer, lipid reserve, bio-accumulation of contaminants (Pethybridge et al, 2013(Pethybridge et al, , 2014 and protein transfer (Carvalho, 2011).…”