Respiration and growth of larval herring Clupea harengus: relation between specific dynamic action and growth efficiency

133

ABSTRACT. A growlng body of evidence suggests that surv~val of the planktonic early life stages of marine fish varies spatially, often in concordance with mesoscale and larger circulation patterns and with spatlal variation in biotic and abiotic factors. Environmental variation experienced by individuals may contribute to variance within the population. Detailed spatial information about life histories cannot b e obtained however, by simply subjecting individuals to identical time series of environmental variates, or adding random noise to the mean values of those variates. In this paper, w e present a numerical biophysical model to address this problem. The model combines a 3-dimensional hydrodynamic model with a probabilistic, life-stage model of young flsh. The oceanographic model is an eddyresolving, semi-spectral primitive e q u a t~o n model (SPEM) adapted for Shelikof Strait and the western Gulf of Alaska, USA. The biological component is a n individual-based model (IBM) which follows each fish through its first 3 mo of life. The 2 models are coupled via a float-tracking algorithm, which advects each fish through the model grid based on the time-varying velocity field derived from the SPEM model, and returns information to the IBM on any physical variables of interest (e.g. temperature and salinity) at the individual's new location. These variables are used to drive biological processes in the IBM. Simulation 1 demonstrates how a probabilistic 1BM using Lagrangian temperature information derived from float tracking can yield significantly different b~ological results than the same model with constant temperature, or a model where all individuals are subjected to identically increasing tlme series of temperature. In Simulation 2 w e compare the float tracks and growth of individuals using a scenario of constant depth for each life stage versus algorithms that include mechanisms producing variable depth. These mechanisms differ for each life stage (e.g. changes in depth due to development of eggs, or die1 migration of feeding larvae). This simulation shows that inclusion of specific mechanisms which determine depth of individual eggs or larvae at particular periods of their development are Important in determ~ning the direction of horizontal advect~on, and the history of exposure to environmental variables for each individual. Simulation 3 compares modeled distributions of the early l~f e stages with distributions derived from field surveys.

Section: Feeding Larval Stagementioning

confidence: 99%

Development of a spatially explicit, individual-based model of marine fish early life history

Hinckley¹,

Aj²,

Ba³

1996

133

“…Effects of body mass (Kiørboe et al 1987) and temperature (Almatar 1984) on R were taken from work on larval herring. The mass of prey consumed was calculated as a function of encounter rate (N SL,i ), prey mass (m i ), capture success (CS SL,i ), handling time (HT SL,i ) and the time interval (Δt ) (Letcher et al 1996): (2) where SL is larval fish standard length and i refers to a specific prey class.…”

Section: Methodsmentioning

confidence: 99%

Physiologically based limits to food consumption, and individual-based modeling of foraging and growth of larval fishes

Peck¹,

Daewel²

2007

Larval fish individual-based models (IBMs) that include foraging subroutines to depict prey encounter, capture and ingestion often include static parameters (e.g. a maximum feeding rate, C MAX ) to prevent 'overfeeding' and unrealistically high growth rates. We formulated 2 physiologically based approaches to limit food consumption rate (C ) based on gut capacity and evacuation rate (GER) and feeding rate-dependent changes in assimilation efficiency (AE ). Parameterizations were based on data reported for a variety of marine and freshwater teleost larvae. The effects of the 3 approaches (C MAX , GER and AE ) on feeding and growth were compared in IBM simulations of 12 mm larval sprat Sprattus sprattus L. foraging within homogenous and patchy prey fields. Prey concentrations for maximum growth were between 5 and 10 copepodites l -1 , similar to thresholds determined for successful foraging by larvae of other marine fish species in laboratory studies. The AE limit allowed larvae to exploit prey patches (to consume prey at higher rates but at lower AEs). In simulations using prey concentrations observed in productive areas of the southern North Sea (e.g. 21.0 copepodites l -1 ), larvae benefited little (benefited much) from adopting this patch feeding strategy when patch prey concentrations were ≤ 2-fold (≥ 5-fold) those outside of the patches. At ≤10 copepodites l -1 , foraging model predictions of C were close to limits imposed by C MAX , GER and AE methods. In patches (20 to 40 copepodites l -1 ), foraging model estimates of C were 2-to 4-fold greater than the highest (AEbased) limit. Physiological-based limits to C are recommended for larval fish IBMs and will be necessary to adequately assess the impacts of prey patchiness on survival and growth of marine fish larvae.

“…Carbon weight of fish larvae was estimated assuming a carbon content of 0.45 µg C µg dry wt -1 (Kiørboe et al 1987).…”

Section: Methodsmentioning

confidence: 99%

Assemblages of fish larvae and mesozooplankton across the continental shelf and shelf slope of the Andaman Sea (NE Indian Ocean)

Munk

Bjørnsen²,

Boonruang³

et al. 2004

Self Cite

We studied the cross-shelf variation in hydrography and plankton dynamics off west Thailand, focusing on physical-biological linkages. The overall research programme investigated linkages between physics, chemistry and plankton biology; in the present paper we consider the findings based on the sampling of fish larvae and mesozooplankton. Surveys were carried out during 2 monsoon periods in March and August 1996, using 3 cross-bathymetric transects extending to the deeper part of the shelf slope of the Andaman Sea. Station distances were either 5 or 10 n miles apart, and at each station a series of net tows were carried out, targeting different size ranges of organisms. Plankton were identified to order (invertebrates) or family (fish larvae), and their abundances and biomass estimated. The abundance of both mesozooplankton and fish larvae peaked mid-shelf (50 to 65 m bottom depth) coinciding with a hydrographic front generated where the pycnocline meets the sea-bottom. An internal wave of pronounced amplitude interacts with the shelf slope at ca. 300 m bottom depth, and findings indicated another zone of enhanced abundance in this area. Analysis of the relative abundances of fish larvae within families revealed a marked cross-shelf structuring into a number of larval assemblages. Distinct assemblages were identified in nearshore areas, at midshelf in the area of the hydrographic front, and off the shelf break in oceanic water. Less pronounced variation was seen in the along-shelf direction and between monsoon periods. KEY WORDS: Fish larval assemblages · Cross-shelf plankton distribution · Frontal hydrography · Monsoon periods Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 274: [87][88][89][90][91][92][93][94][95][96][97] 2004 tion, while fewer studies have been carried out in tropical waters, where hydrographical conditions are different. One characteristic feature of the tropical seas is the strong, permanent temperature stratification of the water column. This is based on the permanent, conspicuous heating of the surface water, and the inflow of a cold subsurface water mass formed outside the tropic region, principally by sinking of water near the subtropical convergence. Wind-induced turbulence mixes heat down from the surface to a specific depth, and a sharp thermocline is established in the depth range of 30 to 50 m. Another characteristic of the tropical seas (from west Africa to SE Asia) is the monsoon seasonality, driven by the twice-yearly passage of the atmospheric inter-tropical convergence zone across the equator. This passage leads to wet/dry seasonality at the coast, dry when the wind blows from the continent, and wet when strong winds blow oceanic air towards the coast. The monsoon periods influence water circulation, and can lead to flow reversal and upward transport of nutrients (Longhurst & Pauly 1987).The monsoon seasonality is likely to exert a strong influence on the tropical shelf ecosystem. However, it has proven difficult to ...