Habitat related growth and reproductive investment in estuarine waters,illustrated for the tellinid bivalve <Emphasis Type="Italic">Macoma balthica</Emphasis> (L.) in the western Dutch Wadden Sea

In estuarine areas, bivalve species can be found in a variety of environments, where they experience large differences in environmental conditions. In the present paper, the importance of different habitats (intertidal, subtidal and adjacent coastal waters) for the persistence of the population was evaluated for the bivalve Macoma balthica (L.) in the western Dutch Wadden Sea estuary. Intra-specific variation in growth and reproductive output were followed during the year and related to local abiotic conditions. Significant differences in growth and reproductive investment were found between locations. Young individuals were mostly found in the intertidal area, where growth in terms of somatic mass was good. These areas were not favourable for adult individuals, since growth in shell length was low and many individuals did not reproduce. In the subtidal, where the highest densities were found, somatic and gonadal mass indices were low. Coastal areas had the lowest densities and showed high growth in terms of shell length and body mass. The habitat with the highest reproductive effort per individual was not the most important habitat in terms of reproductive output due to differences in density and in size of the habitat type. For M. balthica, the subtidal habitat contributed the most to the reproductive output of the western Dutch Wadden Sea population although the highest reproductive output per individual was in the coastal area.     

Effects of Lunatia heros predation on the population dynamics of Mya arenaria and Macoma balthica in Maine,USA

The interaction between the naticid snail predator Lunatia heros and 2 iteroparous, infaunal, intertidal bivalves was investigated in Lubec, Maine, USA. The Mya arenaria population consists primarily of young, small individuals. M. arenaria survivorship is low when young (3.5% yr^-1 for the first 5 yr), then increases. M. arenaria can attain a length of 60 mm, but it is susceptible to L. heros attack only until it is 30 mm long. It delays reproduction until it is 20 mm long (3.8 yr) and diverts its resources instead into rapid early growth (4.9 mm yr^-1 for the first 5 yr). The Macoma balthica population has a larger proportion of older individuals than does that of M. arenaria. Survivorship is higher for M. balthica than for M. arenaria (76.3% yr^-1 for the first 5 yr). Unlike M. arenaria, M. balthica attains a final length of only 25 mm and all sizes are susceptible to L. heros attack. M. balthica grows slowly (2.7 mm yr^-1 for the first 5 yr) and diverts its resources into earlier reproduction at a length of 10 mm (2.9 yr). These contrasting life-history patterns and the possible relationship between bivalve resource allocation and refuges from predation are discussed.     

Active pelagic migrations of the bivalve Macoma balthica are dangerous

The bivalve Macoma balthica migrates twice during the benthic part of its life cycle. During the spring migration (May-June), the newly settled spat (0-group) migrates to the nurseries in the high intertidal. Seven to nine months later, the bivalves migrate back to the low tidal flats and the subtidal (winter migration, 1-group). Both 0- and 1-group M. balthica use byssus threads for active pelagic migrations. As many M. balthica disappear during these migrations, we examined experimentally the importance of predation on 0- and 1-group M. balthica. Laboratory experiments using a circular aquarium determined predation rates on buried (no current) and drifting (current) 0- and 1-group M. balthica by several fish species (plaice, flounder, goby and whiting) and the shore crab. Under illuminated conditions, more M. balthica were consumed when migrating than when buried, whereas there was no difference between experiments in conditions of darkness. For the 0-group, predation rates on migrating and buried M. balthica in the dark were lower than in the light. The stomachs of pelagic fish in the Wadden Sea and Oosterschelde estuary did not contain M. balthica during winter migration. In the Wadden Sea, 1-group M. balthica primarily migrated at night. In conclusion, enhanced predation on drifting, as compared to buried, M. balthica may be the mechanism that explains enhanced mortality during migration in light, and may explain why M. balthica mainly migrates at night in the field. As we found no M. balthica in stomachs of pelagic fish, we do not know whether predation on byssus drifting M. balthica exists in the field. There are, however, some indications for fish predation on infaunal polychaetes during pelagic migrations.     

Natural variability in distribution of an intertidal population of Macoma balthica subject to potential oil pollution at Port Valdez,Alaska

Natural variability in the abundance of an intertidal population of the lamellibranch Macoma balthica (Linnaeus, 1758) was measured during 1971 and 1972 in a study area near the proposed oil storage and tankship loading facility at the southern terminus of the Trans-Alaska pipeline in Port Valdez, Alaska. M. balthica were divided for analysis into a large and a small size category. Small temporal changes in population densities throughout the entire study area were detected for both size categories over several of the 7 sampling times of the 2-year period. Large and persistent differences in density were found among elevation contour intervals for either size category; however, variations in the density profiles on elevation occurred among sampling times. Large M. balthica became more equitably distributed and the small category less equitably distributed among elevation contours over the 2-year period. Densities of both size categories were more stable at the higher elevations of the study site. Large M. balthica were more homogeneously distributed along a given elevation contour interval than the small category. Mobility and time available to redistribute at a horizontal location would explain the more homogeneous distribution of large M. balthica if competition for food resources exists.     

Analysis of growth rate in Mya arenaria using the Von Bertalanffy equation

Field studies were conducted in Gloucester, Massachusetts, USA, to determine linear shell growth rates for Mya arenaria. These rates were then compared with those reported for the same species from other locations. Most shell deposition occurred from March through November of each year. Winter interruptions in growth were not as marked in the small clams as in the larger ones (>60.0 mm). Annual variations in growth were slight during the period 1973–1974. Growth of mature clams (>35.0 mm) slowed during the spawning season. No significant sexual dimorphism in mean annual growth rates was detected. Winter rings were shown to be a reliable method for determining age in clams from Gloucester. Age-size relationships, based on two independent measures of annual growth, winter rings and tagging experiments, were computed using the Von Bertalanffy growth equation. No well-defined latitudinal patcerns in growth could be established for M. arenaria.     

Growth of demersal fish species of the Mexican Pacific Ocean

The growth of 24 species of demersal fish caught off the Sinaloa-Nayarit coast and in the Gulf of Tehuantepec (Mexican Pacific Ocean) was determined by means of length-frequency analysis. Fishes constitute an important bycatch of the penaeid shrimp fishery, and 235 species were identified in catches made on research cruises in both areas in 1989 to 1992. Growth rates (cm yr^-1) ranged from 0.13 cm for lutjanids and serranids to 0.95 cm for the carangid Selene peruviana; the other species displayed growth rates within this range. Growth varied seasonally, with minimum growth in spring, and is probably related to seasonal changes in the waters of the area. By means of length-frequency analysis, we determined von Bertalanffy growth parameters for the primary species of this multispecies fishery. Such data is fundamental for the future commercial exploitation of these fishes.     

Application of a temperature-dependent von Bertalanffy growth model to bullhead (Cottus gobio)

The most studied and commonly applied model of fish growth is the von Bertalanffy model. However, this model does not take water temperature into account, which is one of the most important environmental factors affecting the life cycle of fish, as many physiological processes that determine growth, e.g. metabolic rate and oxygen supply, are directly influenced by temperature. In the present study we propose a version of the von Bertalanffy growth model that includes mean annual water temperatures by correlating the growth coefficient, k, explicitly and the asymptotic length, L_∞, implicitly to water temperature. All relationships include parameters with an obvious biological relevance that makes them easier to identify. The model is used to fit growth data of bullhead (Cottus gobio) at different locations in the Bez River network (Drme, France). We show that temperature explains much of the growth variability at the different sampling sites of the network.     

Otolith age validation and growth-rate variation in flyingfish (Hirundichthys affinis) from the eastern Caribbean

A study of otolith aging and growth-rate variation in the flyingfish Hirundichthys affinis (Günther) was conducted in the eastern Caribbean (10–16°N; 58–62°W) in 1987–1989. Daily otolith-increment formation was validated in laboratory-reared larvae, confirming the usefulness of otolith-increment counts for age determination of H. affinis juveniles (<150 mm fork length, FL). A mark-recapture programme to validate increment formation in wild adults was unsuccessful due to tetracycline-linked mortality and insufficient tetracycline uptake in slow-growing adult otoliths. A von Bertalanffy growth curve fitted to juvenile size-at-age data gave preliminary growth-curve parameters of t ₀=2.85 d and k=0.00854 on a daily basis, with an asymptotic length, L, of 245 mm FL, for eastern Caribbean flyingfish. Juvenile growth rate in H. affinis is sensitive to spatial and temporal variation in temperature. Growth rates were higher where sea-surface temperatures were higher, and were higher for juveniles hatched in warmer months (April–July) than in colder months (November–March). Growth rates were also higher near islands than at more oceanic locations. Variation in juvenile growth rates may influence the spatial and temporal variation in spawning frequency observed in H. affinis.     

A natural history study of Encope grandis and Mellita grantii,two sand dollars in the northern gulf of California,Mexico

Populations of the sand dollars Encope grandis and Mellita grantii were studied at Playa Hermosa in the northern Gulf of California, Mexico. Intertidal distribution and abundance were estimated for the two species from 1969 to 1972. They occurred in the lower intertidal (-0.4 to -1.3 m) and on into the subtidal. Density of E. grandis varied from a high of 380/m² in the spring of 1970 to a low of 0.1/m² in the fall of 1971. Density of M. grantii ranged from a high of 56/m² in 1970 to a low of 0.8/m² in 1971. Growth curves were constructed based on shifts in the modes of the size distributions, and rates of mortality were estimated from the growth parameters and size distributions. It is estimated that E. grandis would attain 95% of its maximum size (74 mm) in about 6 years with an annual mortality rate of 18%. M. grantii would reach 95% of its maximum size (38 mm) in about 5 years with an annual mortality rate of 58%. The populations of these sand dollars appear to be limited by the physical environment.     

Sublethal effects of chronic oil exposure on the intertidal clam Macoma balthica

When exposed to Prudhoe Bay crude oil in flowing seawater for 180 days, the small intertidal clam Macoma balthica showed behavioral, physical, physiological and biochemical changes. At a high concentration of oil in seawater (3.0 mg l^-1) burrowing rate decreased, respiration rate increased, growth was inhibited, and very high mortalities resulted. The lowest concentration of oil in seawater (0.03 mg l^-1) inhibited growth and caused reabsorption of gametes. One group of adverse oil effects which was related to sluggishness and disorientation of the clams appeared after a week of exposure to oil; another group related to a negative energy balance was not observed until 60 days. We conclude that chronic exposure of M. balthica to oil-in-seawater concentrations even as low as 0.03 mg l^-1 will, in time, lead to population decreases.Please address requests for reprints to Dr. D. G. Shaw at the Institute of Marine Science     

Genetic affinities of the bivalve Macoma balthica from the Pacific coast of North America: evidence for recent introduction and historical distribution

The tellinid bivalve Macoma balthica (L.) has an extensive geographic range that reaches from temperate to arctic coastal waters in the North Atlantic and North Pacific oceans. Recent studies have indicated that eastern and western North Atlantic populations are morphologically and genetically different from one another, and that they may have diverged as sibling species. To determine the genetic relationship between M. balthica from the Pacific and Atlantic coasts of North America, populations from each coast were examined at 11 enzyme loci using standard starch gel electrophoresis. Allele frequency data indicate that M. balthica populations from San Francisco Bay, California appear more closely related to western North Atlantic populations than to populations from Oregon. We suggest that San Francisco Bay populations were introduced relatively recently from western North Atlantic populations. The Oregon populations are probably a natural extension of northern populations that occur along Northern Asia and in the eastern North Atlantic.     

Growth and life span of the small octopus Octopus tehuelchus in San Matías Gulf (Patagonia): three decades of study

Phenotypic plasticity in response to environmental variability is one of the main characteristics of cephalopods. This study compares growth and life span of Octopus tehuelchus in different coastal environments of San Matías Gulf (Patagonia) at three different periods. The progression of maturity jointly with modal progression analysis and the detection of hatchlings in the natural environment were used to differentiate cohorts and assign ages. Growth was described using the oscillatory von Bertalanffy growth model. Within San Antonio Bay, O. tehuelchus seems to have the most favourable conditions for an extended spawning season and the development of two sub-annual cohorts. O. tehuelchus growth is strongly seasonal with slow growth rates during winter. There were differences in the growth pattern between sites and particularly between sub-annual cohorts in San Antonio Bay. The growth pattern in each site seems to be similar along the last 26 years. The results of our study make evident the variability and plasticity of O. tehuelchus in response to the environment.     

Spatial variability of length-specific production in shell,somatic tissue and sexual products of Macoma balthica in the Lower St. Lawrence Estuary

A field study on the spatial variability of production and some demographic parameters was conducted in 1988 in ten populations of Macoma balthica located on the north and south shores along the entire length (230 km) of the Lower St. Lawrence Estuary (LSLE, Canada) at the same intertidal level. Standard-length estimates (10 mm) of shell and somatic tissue production for the period of May to November were highly variable between stations and greater on the north shore than on the south shore. Standard-length estimates of the gamete production for the period of July to November were also highly variable between stations but there was no variation between shores. The inter-population variability of the standard-length estimates of production in shell, somatic tissue and sexual products was as large as the intrapopulation variability between both the upper and lower tidal levels measured in previous studies. There were no significant linear relationships between standard-length estimates of production and biotic (density) or abiotic (temperature, chlorophyll-a in top sediment, mean phi, water salinity) factors, but we observed some significant quadratic relationships between standard-length estimates of production and mean sediment-surface temperature during the growing season. The standard-length estimates of production were lower at the coldest and warmest stations than at the more temperature stations. There was also a significant negative linear relationship between mean sediment-surface temperature during the growing season and the grain size structure of sediment, indicating that the sediment texture, indirectly, largely influenced the inter-station and the inter-shore variability of production in shell, somatic tissue and sexual products of M. balthica in the LSLE.     

Continuous growth facilitates feeding and reproduction: impact of size on energy allocation patterns for organisms with indeterminate growth

Body size has great influence on feeding, reproduction, and ecological importance. This study measures growth, reproduction, and feeding for several northeastern Pacific intertidal invertebrates that have indeterminate growth. In all species studied, linear size (length, diameter) showed asymptotic growth fit by the von Bertalanffy growth function, supporting the notion that less energy is allocated to growth with age because of increased reproduction. However, these same species displayed a continuous, roughly linear increase in volume with age. Both reproductive output and food intake were shown to scale proportionally with volume. This indicates that some species with indeterminate growth do not reduce energy allocation to growth with age but instead display continuous volumetric growth that facilitates increases in feeding rate and reproductive output with age and size. A simple allometric model is proposed to describe constant volumetric growth rates and linear increases in reproduction with age.     

Allometry and growth of the green-lipped mussel Perna canaliculus in New Zealand

Length is the most precise (and the most practical) linear measurement for predicting total weight (r>0.98 at P=0.001) in the green-lipped mussel Perna canaliculus Gmelin. The allometry varies with the environmental conditions under which the mussels grow, resulting in morphologically distinct forms of raft- and shore-grown mussels. Mussels grown intertidally are wider, less high and heavier than mussels of similar length grown in suspension. Increase in length and total weight of P. canaliculus grown in suspended cultivation was recorded at 8 experimental sites around New Zealand, during 1973–1975. Comparisons are drawn with growth on an intertidal mussel bed, where length increase was less than half that in the same period in suspension. The growth rate of mussels transferred from intertidal to suspended conditions depends on the size at transfer. Close similarity in growth rate occurred at the majority of sites in spite of a direct correlation between water temperature and length increment and substantial, differences in temperature between sites. Reasons for the uniformity are suggested. Average values for growth at sites over the northern half of New Zealand were 73 mm length (32.5 g weight) after 12 months, 113 mm (110 g) after 2 years. Growth continued throughout the year, highest growth rates corresponding to highest water temperatures. Variation due to depth was not significant. Larger mussels grew more slowly. P. canaliculus can be grown in suspended cultivation in New Zealand at a rate comparable to that in other commercial mussel-farming areas.     

Density-dependent growth in the Atlantic surfclam, Spisula solidissima, off the coast of the Delmarva Peninsula, USA

Spisula solidissima (Dillwyn, 1817) is a large, suspension-feeding bivalve, whose range extends from Nova Scotia to South Carolina. This species is harvested commercially. Shell length and age data were collected for this species from 1980 to 1994 during surveys of population size and structure. These data were used to examine the relationship between the growth rate of S.␣solidissima and intraspecific density. The null hypothesis was that density (represented by number of individuals per tow) would have no effect on rate of growth. A negative relationship would support the alternative hypothesis, that intraspecific competition had taken place. This analysis focused on the surfclam population offshore from the Delmarva Peninsula, USA because: (1) a major recruitment event occurred in 1977, (2) clam fishermen had reported “stunted” surfclams in that area, (3) a wide range of local densities were available to examine, and (4) the existence of a closed area within the study area set up an interesting contrast with areas left open to harvesting. Maps of surfclam abundance across the Delmarva region demonstrate that areas of highest density have generally remained in the same location through time. The results suggested that intraspecific competition has been important in structuring this population. Based on data from 1980 to 1992, shell length was significantly reduced at high density, and a significant interaction between age and density was observed. Growth modeling indicated decreased asymptotic lengths and growth rates with increasing density. In nine out of ten pairwise randomization tests, fitted von Bertalanffy growth curves, representing different densities, were significantly different from each other. High densities of clams have persisted in the area that was closed to harvesting for 11 years (1980 to 1991). In 1994, length at age was significantly less in this closed area compared to that in the surrounding area. This effect was apparent in clams from 3 to 17 years of age, and most pronounced in the cohort that recruited to the Delmarva region in high numbers in 1977. Lower growth rates within the closed area have management implications for the optimal duration of closures. Received: 16 May 1997 / Accepted: 7 October 1997     

The “Tsesis” oil spill: Acute and long-term impact on the benthos

The “Tsesis” oil spill in October 1977 resulted in the release of over 1 000 tons of medium grade fuel oil in an archipelago in the brackish Baltic Sea. Considerable oil quantities reached the benthos by sedimentation. Within 16 d benthic amphipods of the genus Pontoporeia, as well as the polychaete Harmothoe sarsi Kinberg, showed reduction to less than 5% of pre-spill biomasses at the most impacted station. The clam Macoma balthica (L.) was more resistant, and showed little or no mortality, but was heavily contaminated by oil (about 2 000 μg g^-1 dry wt total hydrocarbons). The meiofauna was strongly affected, with ostracods, harpacticoids, Turbellaria and kinorhynchs showing clear reductions in abundance, while nematodes, as a group, were more resistant. In the winter following the spill gravid Pontoporeia affinis Lindström females showed a statistically significant increase in the frequency of abnormal or undifferentiated eggs. Food-chain transfer of oil to flounder [Platichthys flesus (L.)] was indicated. Not until the second summer after the spill were the first signs of recovery noted at the most heavily impacted station: Amphipods, H. sarsi and harpacticoids increased and the oil concentrations in M. balthica decreased (to about 1 000 μg g^-1). In the area where amphipods had been virtually eliminated, there was an unusually heavy recruitment of M. balthica, reaching 4 000 juveniles, of 1.5–2 mm length, per square metre, probably from settling in summer 1978. Three years after the spill Pontoporeia spp. biomass was still depressed in the most affected area, while H. sarsi showed normal biomass, and M. balthica abundance was inflated. Oil concentrations in M. balthica (about 250 μg g^-1) and flounder were only slightly elevated and the oil could no longer be confidently ascribed to “Tsesis” origin, even using GC/MS-analysis. Recovery was thus underway, but the long lifespan of M. balthica implies that the disturbed community composition may persist for many years at this station. Full recovery is likely to require more than 5 yr and may take a decade or more. An effort to evaluate the accumulated monetary loss to fishery from the accident indicates that direct costs of shoreline cleanup and vessel damage were considerably greater.     

Temporal, spatial, and body size effects on growth rates of loggerhead sea turtles (Caretta caretta) in the Northwest Atlantic

In response to a call from the US National Research Council for research programs to combine their data to improve sea turtle population assessments, we analyzed somatic growth data for Northwest Atlantic (NWA) loggerhead sea turtles (Caretta caretta) from 10 research programs. We assessed growth dynamics over wide ranges of geography (9–33°N latitude), time (1978–2012), and body size (35.4–103.3 cm carapace length). Generalized additive models revealed significant spatial and temporal variation in growth rates and a significant decline in growth rates with increasing body size. Growth was more rapid in waters south of the USA (<24°N) than in USA waters. Growth dynamics in southern waters in the NWA need more study because sample size was small. Within USA waters, the significant spatial effect in growth rates of immature loggerheads did not exhibit a consistent latitudinal trend. Growth rates declined significantly from 1997 through 2007 and then leveled off or increased. During this same interval, annual nest counts in Florida declined by 43 % (Witherington et al. in Ecol Appl 19:30–54, 2009) before rebounding. Whether these simultaneous declines reflect responses in productivity to a common environmental change should be explored to determine whether somatic growth rates can help interpret population trends based on annual counts of nests or nesting females. Because of the significant spatial and temporal variation in growth rates, population models of NWA loggerheads should avoid employing growth data from restricted spatial or temporal coverage to calculate demographic metrics such as age at sexual maturity.     

Laboratory growth of early juveniles of the western rock lobster Panulirus longipes cygnus

Growth in the laboratory of early juvenile Panulirus longipes cygnus George from the last larval (puerulus) stage to approximately 3 years of age is described. Specimens were held either in isolation or in groups of 3 or 5 rock lobsters per tank, at constant temperatures of 20° or 23°C (both ± 0.5 C°) or at the temperatures of the incoming seawater, which ranged annually between 14.9° and 25.9°C. Metamorphosis from the planktonic puerulus to the settled juvenile existence involved a reduction in size and usually took about two moults to complete. By this time the sexes could be distinguished. Growth in aquaria from the 2nd moult after puerulus until the juveniles were approximately 3 years of age was adequately described by exponential (von Bertalanffy) functions, with the growth curves gradually tapering off after the rock lobsters had reached 40 to 42 mm carapace length. Young juveniles were not gregarious until 20 to 25 mm carapace length (approximately 1.5 years old), however, growth rates were not depressed in individuals held in isolation up to approximately 3 years of age. Temperature markedly affected growth; the fastest observed growth up to 450 days was at 23°C. Variations in temperature resulted in decreased growth rates in winter and the reverse in summer in individuals at ambient temperatures. There was an increase in the moult increment at successive moults corresponding to increased carapace length, but increased growth rates were achieved through shortening the intermoult duration. The period of development from the puerulus stage until approximately 1.5 years of age is a distinct phase of development both of behaviour and growth.