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Occurrence and life history characteristics of tropical flatfishes at the coral reefs of Curaçao, Dutch Caribbean

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Abstract

In this paper, life history characteristics of tropical flatfishes occurring at the fringing reefs of Curaçao to a depth of 20 m were studied. In total four flatfish species were caught, three common Bothidae species: the eyed flounder Bothus ocellatus, the mottled or maculated flounder B. maculiferus and the peacock flounder B. lunatus, and –in small numbers- the channel flounder Syacium micrurum. B. ocellatus and S. micrurum only occurred in sandy moats on the shallow reef terrace and fore reef and between coral patches on the terrace and fore reef slope. The other species could also be found on coral patches. The depth distribution of the various species overlapped: all species were caught over a depth range from a few meters up to 20 m. All Bothus species were carnivores, preying on a variety of mobile benthic animals such as fishes and crustaceans. Reproduction seemed to occur year round in all three Bothus species. Growth between the species varied considerably with a maximum age found in B. maculiferus and B. lunatus of a little over 1 year, and in B. ocellatus of about 2 years. Growth was lowest in B. ocellatus and highest in B. lunatus: after one year B. ocellatus was about 10 cm in size, B. maculiferus 25 cm and B. lunatus about 35 cm. After correction for differences in water temperature, the Bothus species showed a similar variability and range in growth rate as some temperate and subtropical flatfish species. These observations do not fit the hypothesis postulated by Pauly (1994) of an increasing importance of food-limitation in juvenile flatfish with decreasing latitude, despite the low densities and biomass of benthic in- and epifauna in the soft sediments in mangroves, seagrass beds and the reefs of Curaçao

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Juvenile flatfish were studied in a tropical estuary, Arquipélago dos Bijagós in Guinea-Bissau from October 1992 until April 1993. A total of eight flatfish species, belonging to the families Bothidae, Cynoglossidae, Psettodidae and Soleidae, were found. In comparison with other fish groups, flatfishes abundance was low with densities of less than 13 ind·100 m−2. One species, Citharichthys stampflii, occurred in densities high enough to permit an analysis of distribution, growth and mortality. During the period of study, settlement of C. stampflii was observed in the estuary. Its distribution suggested a preference for offshore areas, densities decreasing towards the river systems. Repeated sampling in the intertidal area of Ilheu de Flamingos permitted a preliminary estimate of mortality and growth. Instantaneous mortality rates were about 0.03·d−1, which is similar to estimates in temperate estuaries. Growth rates were slightly above 1 mm·d−1, about the same as those measured in subtropical estuaries.
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Melolobium is a hitherto poorly known southern African papilionoid genus of the family Fabaceae. Although 20 species have previously been described, in the present revision we recognise only 15 species. The genus appears to have close affinities with a number of other African genistoid genera (Adenocarpus, Argyrolobium, Dichilus and Polhillia) but can be distinguished by the often spiny habit, auriculate stipules and presence of glands (stalked and sessile) in most species of the genus. A cladistic analysis of morphological and anatomical characters resulted in a fully resolved cladogram in which virgate, non-spiny species are basal to the divaricately branched spiny group of species. The correct nomenclature, typification of names, descriptions, geographical distributions and a key to all the species of Melolobium are presented.
Article
The quantitative aspects of growth and reproduction in four flatfish species (plaice, flounder, dab, sole) in terms of energy flow are described on the basis of a dynamic energy budget (DEB theory). This theory consists of general assumptions about energy uptake, storage and utilisation and describes an individual by two state variables: structure and reserve, whereby body size exerts its influence through the ratio between surface area and volume. Comparison between model estimates and field data shows that the DEB model successfully describes the energetics of growth and reproduction in a number of flatfish species. Differences between species could be captured in the same model using different parameter values. Intraspecific differences in growth between males and females are mainly caused by differences in maximum surface area-specific ingestion rates. Differences between species are reflected in the surface area-specific maximum ingestion rate, the energy partitioning over growth and reproduction, and in egg volume. According to these parameters at 283 K (10°C), the species could be ranked as follows: surface area-specific maximum ingestion rate (W m−2) plaice: 56.6; flounder: 54.5; sole: 45.1 and dab: 36.1 W m−2. Fraction of energy allocated to reproduction (–): flounder: 0.35; plaice: 0.15; dab: 0.15 and sole 0.10. As a consequence of these differences in surface area-specific maximum ingestion rate and in the fraction of utilised energy allocated to reproduction, the gonad masses (g) of females of 0.5 kg wet mass differ considerably: flounder: 149 g; plaice: 86 g; sole: 70 g; and dab: 69 g. However, due to differences in egg size between species, the potential annual egg production shows a completely different pattern: dab: 2200 103; flounder: 1560 103; sole: 343 103 and plaice: 130 103 eggs.
Article
Recent work by Reiss and Ogden provides a theoretical basis for sometimes preferring restricted maximum likelihood (REML) to generalized cross-validation (GCV) for smoothing parameter selection in semiparametric regression. However, existing REML or marginal likelihood (ML) based methods for semiparametric generalized linear models (GLMs) use iterative REML or ML estimation of the smoothing parameters of working linear approximations to the GLM. Such indirect schemes need not converge and fail to do so in a non-negligible proportion of practical analyses. By contrast, very reliable prediction error criteria smoothing parameter selection methods are available, based on direct optimization of GCV, or related criteria, for the GLM itself. Since such methods directly optimize properly defined functions of the smoothing parameters, they have much more reliable convergence properties. The paper develops the first such method for REML or ML estimation of smoothing parameters. A Laplace approximation is used to obtain an approximate REML or ML for any GLM, which is suitable for efficient direct optimization. This REML or ML criterion requires that Newton-Raphson iteration, rather than Fisher scoring, be used for GLM fitting, and a computationally stable approach to this is proposed. The REML or ML criterion itself is optimized by a Newton method, with the derivatives required obtained by a mixture of implicit differentiation and direct methods. The method will cope with numerical rank deficiency in the fitted model and in fact provides a slight improvement in numerical robustness on the earlier method of Wood for prediction error criteria based smoothness selection. Simulation results suggest that the new REML and ML methods offer some improvement in mean-square error performance relative to GCV or Akaike's information criterion in most cases, without the small number of severe undersmoothing failures to which Akaike's information criterion and GCV are prone. This is achieved at the same computational cost as GCV or Akaike's information criterion. The new approach also eliminates the convergence failures of previous REML-or ML-based approaches for penalized GLMs and usually has lower computational cost than these alternatives. Example applications are presented in adaptive smoothing, scalar on function regression and generalized additive model selection.
Chapter
The dynamic energy budget (DEB) theory for metabolic organisation specifies quantitatively the processes of uptake of substrate by organisms and its use for the purpose of maintenance, growth, maturation and reproduction. It applies to all organisms. Animals are special because they typically feed on other organisms. This couples the uptake of the different required substrates, and their energetics can, therefore, be captured realistically with a single reserve and a single structure compartment in biomass. Effects of chemical compounds (e.g. toxicants) are included by linking parameter values to internal concentrations. This involves a toxico-kinetic module that is linked to the DEB, in terms of uptake, elimination and (metabolic) transformation of the compounds. The core of the kinetic module is the simple one-compartment model, but extensions and modifications are required to link it to DEBs. We discuss how these extensions relate to each other and how they can be organised in a coherent framework that deals with effects of compounds with varying concentrations and with mixtures of chemicals. For the one-compartment model and its extensions, as well as for the standard DEB model for individual organisms, theory is available for the co-variation of parameter values among different applications, which facilitates model applications and extrapolations. KeywordsDynamic energy budgets–Effects on processes–Kinetics–Metabolism–Transformation
Article
The ecology of juvenile plaice, Pleuronectes platessa L., of the O-, I- and II-group in the western Wadden Sea has been studied on the Balgzand intertidal flats during the years 1972 through 1975. The present paper deals especially with density, growth and food-intake on 4 representative sampling squares, intensively sampled from March to October 1973.The O-group arrived as new settlers in the intertidal zone in April and reached maximum densities in June; the I- and II-group repopulated the area as early as March, reaching peak densities in May. In June and July densities of all age groups decreased rapidly, on the one hand as the result of mortality (the O-group) and on the other through emigration (I- and II-group). Since mortality in O-group decreased abruptly in July, from this age group relatively large numbers remained in the intertidal zone until October (end of observation period).Growth of O-group plaice on the Balgzand was relatively high as compared to that of the German Wadden Sea and British coastal waters. In I-group and particularly in II-group plaice, growth may be under-estimated due to gradual emigration of larger individuals.Study of the length-weight relation showed isometric growth in I- and II-group, and an allometric growth in the O-group; the smallest plaice were “too heavy” for their length.From density and growth data the productivity of the plaice populations was followed in the course of the seasons. Top values were found in April–May (II-group), May–June (I-group) and in June–July (O-group). Total production of plaice tissue was estimated at about 5 grammes wet-weight per m2 in the growing period (March through October).Data on stomach contents and gastric digestion led to a description of the food composition, and to estimates on individual feeding rates, food conversion and population food-intake. When individual feeding rate is expressed relatively to weight of the fish, feeding appeared to be most intensive in spring. The same applies to the conversion of food into body tissues. Superimposed on this seasonal effect, both feeding rate per gramme fish and food conversion are negatively related to the age (or size) of the plaice.From data on population density and the individual feeding rate, population food-intake—predation pressure—was followed in the course of the season. Total food-intake in grammes ashfree dry-weight per m2 from March to October amounted to 0.25 g (O-group), 0.43 g (I-group) and 4.35 g (II-group); in total to about 5 grammes. Predation on the benthic invertebrate populations appeared to be most intensive from April to June. The biomass of the macro-benthos, however, showed in the same period an increase from 80% to 120% of the yearly average. Apparently maximum predation coincides with maximum productivity of the benthic invertebrates.Since survival and growth conditions seem to be very favourable on the Balgzand, the importance of the Wadden Sea as a nursery for the North Sea plaice was discussed.
Article
The population dynamics of juveniles of some flatfish species were studied in the Duplin River, a tidal creek in a subtropical salt-marsh area in Georgia, U.S.A. from April until September 1990. Seven species were found. Paralichthys dentatus, Paralichthys lethostigma, Paralichthys oblongus and Trinectus maculatus were relatively rare. Etropus crossotus, Citharichthys spilopterus and Symphurus plagiusa were abundant and settled during the period studied. E. crossotus was the most abundant species with a mean abundance of 18 ind·10−2 m−2 (max. 287). Demersal settlement of E. crossotus took place in shallow areas and over sandy bottoms from mid-May to August. Prolonged settlement hampered the calculation of growth rate and instantaneous mortality rate. However, laboratory growth experiments indicated a mean growth of about 0.50 mm·d−1 at 24–28°C. Juveniles of C. spilopterus were already present in the Duplin River in March. Settling continued until the end of April with a mean abundance of 3.5 ind·10−2 m−2 (max. 183). With increasing size the juveniles of this species tended to migrate to deeper waters and to the mouth of the river, possibly as a reaction to increasing water temperatures. Maximum growth rate was 1.4 mm·d−1 at about 26°C. The mean instantaneous mortality rate (z) was estimated at 0.03·d−1. Settling of S. plagiusa occurred from mid-May onwards. The mean abundance was 10.3 ind·10−2 m−2 (max. 98.3). Newly settled juveniles were most abundant on muddy sediments in the shallow river areas. The maximum growth rate was 1.3 mm·d−1 at about 28°C. The mean instantaneous mortality rate (Z) decreased from 0.04·d−1 in April to 0.01·d−1 in August. At all sites the abundance of juveniles of this species decreased with increasing water depth. Predation experiments indicated that blue crabs (Callinectes similis and C. sapidus) and sea robins (Prionotus sp.) are potential predators on juvenile flatfish. The high abundances of juvenile flatfish indicate that the tidal creeks are an important nursery area. The correspondence between growth rates estimated from field data and those observed in the laboratory suggests that growth in the nursery is mainly related to water temperature and not food limited.
Article
Some major latitudinal trends in the physiology, population dynamics and ecology of flatfish are illustrated, and related to their ultimate cause: temperature-mediated difference of metabolic rate. The niche of tropical flatfish is then defined with some emphasis on Psettodes erumei in the Gulf of Thailand, and a hypothesis is derived to explain the generally low observed biomass—and hence recruitment of tropical flatfish. It is stated that flatfish are overadapted to feeding on zoobenthic in- and epifauna. In combination with a trend of decreasing importance of the benthic system towards the tropics, this suggests an increasing importance of food-limitation with decreasing latitude and as a consequence lower biomass values. Furthermore, the general increase of maintenance metabolism with temperature reduces in tropical systems the size of flatfish at which oxygen limits further growth. This aspect is responsible for the general trend of a smaller flatfish size with decreasing latitude. Finally, implications for future flatfish research are discussed.
Article
Preface 1. Energetics and models 2. Basic concepts 3. Energy acquisition and use 4. Uptake and use of essential compounds 5. Multivariate DEB models 6. Uptake and effects of non-essential compounds 7. Case studies 8. Comparison of species 9. Living together 10 Evaluation Bibliography Glossary Notation and symbols.
Length-weight relationships of selected marine reef fishes from the southeastern United States and The Caribbean
  • J A Bohnsack
  • D E Harper
Bohnsack, J.A., Harper, D.E., 1988. Length-weight relationships of selected marine reef fishes from the southeastern United States and The Caribbean. NOAA Tech. Mem. NMFS-SEFC-215, 31 pp.
Temporal and spatial patterns in the soft -bottom c ommunities along the coasts of Curaçao
  • S Bremer
Bremer, S., 1997. Temporal and spatial patterns in the soft -bottom c ommunities along the coasts of Curaçao, Netherlands Antilles. NIOZ-rapport 1997-2, 27 pp.
Bony fishes part 2 (Opistognathidae to Molidae), sea turtles and marine mammals. FAO Species Identification Guide for Fishery Purposes and
  • K E Carpenter
Carpenter, K.E. (ed.), 2002. The living marine resources of the Western Central Atlantic. Volume 3: Bony fishes part 2 (Opistognathidae to Molidae), sea turtles and marine mammals. FAO Species Identification Guide for Fishery Purposes and American Society of Ichthyologists and Herpetologists Special Publication No. 5. FAO, Rome, 1375-2127.
FSA: Fisheries Stock Analysis
  • D H Ogle
Ogle, D.H., 2017. FSA: Fisheries Stock Analysis. R package version 0.8.17.
Early stages of Atlantic fishes: An identification guide for the Western Central North Atlantic, Two volume set
  • W J Richards
Richards, W.J., 2005. Early stages of Atlantic fishes: An identification guide for the Western Central North Atlantic, Two volume set, CRC Press, Boca Raton, 1312 pp
Coral reef fishes. Dynamics and diversity in a complex ecosystem
  • P F Sale
Sale, P.F., 2002. Coral reef fishes. Dynamics and diversity in a complex ecosystem. Acad Press, Amsterdam, 549 pp.
Florida Marine Resources Institute, Dept. Nat. Resources., Mem. Hourglass Cruises
  • R W Top
  • F H Hoff
Top, R.W., Hoff Jr, F.H., 1972. Flatfishes (Pleuronectiformes). Florida Marine Resources Institute, Dept. Nat. Resources., Mem. Hourglass Cruises. 4, 135 pp.