Osmoregulatory capacity and the ability to use marine food sources in two coastal songbirds (Cinclodes: Furnariidae) along a latitudinal gradient

Cinclodes nigrofumosus and C. oustaleti are two closely related songbirds that inhabit the northern Chilean coast during the austral fall and winter.This stretch spans a dramatic north to south latitudinal gradient in rainfall and temperature. Whereas C. nigrofumosus lives exclusively on coastal environments, C. oustaleti shifts seasonally from coastal environments to inland freshwater ones. We used the δ¹³C of these two species’ tissues to investigate whether the reliance on marine versus terrestrial sources varied from the hyper-arid north to the wet south. We also investigated latitudinal variation in the renal traits that mediate how these birds cope with dehydration and a salty marine diet. Both species increased the incorporation of terrestrial carbon, as measured by δ¹³C, as terrestrial productivity increased southwards. However, C. nigrofumosus had consistently more positive (i.e. more marine) and less variable δ¹³C values than C. oustaleti. The osmoregulatory traits of both species varied with latitude as well. Urine osmolality decreased from extremely high values in the north to moderate values in the south, while C. nigrofumosus produced more concentrated urine than C. oustaleti. In both species, the proportion of kidney devoted to medullary tissue decreased from north to south, and kidney size increased significantly with latitude. Cinclodes nigrofumosus had larger kidneys with larger proportions of medullary tissue than C. oustaleti. C. nigrofumosus and C. oustaleti are terrestrial organisms subsidized by a rich marine environment where it is adjacent to an unproductive terrestrial. Variation in the reliance on marine food sources seems to be accompanied by adjustments in the osmoregulatory mechanisms used by these birds to cope with salt and dehydration.     

Coping with salt without salt glands: osmoregulatory plasticity in three species of coastal songbirds (ovenbirds) of the genus<Emphasis Type="Italic"> Cinclodes</Emphasis> (Passeriformes: Furnariidae)

We investigated the phenotypic plasticity of renal function in three South American coastal passerine Cinclodes (ovenbirds) differing in the proportion of marine prey they consume. Individuals were acclimated to two regimes of salinity for 15 days, and then the maximal urine-concentrating ability (U_max), hematological parameters and kidney morphology of each species were determined. The proportion of kidney mass occupied by medullary tissue, the number of medullary cones in the kidneys, plasma osmolality and U_max differed among the three species, supporting the hypothesis of an adaptation for excretion of the high salt load in the strictly marine C. nigrofumosus. Our results indicate that species of Cinclodes are able to modify the proportion of medullary tissue and the U_max. In addition, we found interspecific differences in the magnitude to which these osmoregulatory parameters can be modified. The greater ability to modify the osmoregulatory features in the migrant species C. oustaleti may enable it to cope with seasonal changes in salt load imposed by the winter consumption of hypertonic prey.Abbreviations U_max maximal urine concentration - SW salt water - TW tap waterCommunicated by I.D. Hume     

Dietary and isotopic specialization: the isotopic niche of three <Emphasis Type="Italic">Cinclodes</Emphasis> ovenbirds

By comparing the isotopic composition of tissues deposited at different times, we can identify individuals that shift diets over time and individuals with constant diets. We define an individual as an isotopic specialist if tissues deposited at different times have similar isotopic composition. If tissues deposited at different times differ in isotopic composition we define an individual as an isotopic generalist. Individuals can be dietary generalists but isotopic specialists if they feed on the same resource mixture at all times. We assessed the degree of isotopic and dietary specialization in three related Chilean bird species that occupy coastal and/or freshwater environments: Cinclodes oustaleti, Cinclodes patagonicus, and Cinclodes nigrofumosus. C. oustaleti individuals were both isotopic and dietary generalists. Tissues deposited in winter (liver and muscle) had distinct stable C (δ¹³C) and stable N isotope ratio (δ¹⁵N) values from tissues deposited in the summer (wing feathers) suggesting that birds changed the resources that they used seasonally from freshwater habitats in the summer to coastal habitats in the winter. Although the magnitude of seasonal isotopic change was high, the direction of isotopic change varied little among individuals. C. patagonicus included both isotopic specialists and generalists, as well as dietary specialists and generalists. The isotopic composition of the feathers and liver of some C. patagonicus individuals was similar, whereas that of others differed. In C. patagonicus, there were large inter-individual differences in the magnitude and the direction of seasonal isotopic change. All individuals of C. nigrofumosus were both isotopic and dietary specialists. The distribution of δ¹³C and δ¹⁵N values overlapped broadly among tissues and clustered in a small, and distinctly intertidal, region of δ space. Assessing individual specialization and unraveling the factors that influence it, have been key questions in animal ecology for decades. Stable isotope analyses of several tissues in appropriate study systems provide an unparalleled opportunity to answer them.     

Comparative isotopic natural history of two native passerines (Troglodytes cobbi and Cinclodes antarcticus) and the invasive rats (Rattus norvegicus) that extirpate them

While several studies have shown that invasive rats can have negative effects on island birds through predation (both direct predation and nest predation), other mechanisms for the effects of invasives on island biota have been given less attention. Here, we explore another potential mechanism by which invasive rats can affect native island birds: the competitive use of common resources. We used stable isotope analyses to estimate the fraction of marine and terrestrial sources incorporated into the tissues of two species of passerines (Troglodytes cobbi, Troglodytidae; and Cinclodes antarcticus, Furnariidae) and Norway rats (Rattus norvegicus, Muridae) in the Falkland Islands. These two passerines are absent on islands where rats are present. We found significant incorporation of marine resources in the three species, with the highest incorporation in tissues of T. cobbi. This species appears to be one of the passerines most reliant on marine sources and the most marine member of the family Troglodytidae. We also used the results of these isotopic analyses to estimate the isotopic niche breadth of each of these species and the isotopic niche overlap among them. Rattus norvegicus had a large isotopic niche that overlapped broadly with those of the two passerine species. We propose that different ways of both depicting and estimating isotopic niche widths are complementary rather than alternative. Our results are consistent with the notion that invasive rats might have an impact on these two species of Falkland Island passerines by using common resources but do not rule out the possibility that part of their effect is through direct predation.     

Geographical differentiation inferred from flavonoid content between coastal and freshwater populations of the coastal plant Lathyrus japonicus (Fabaceae)

Lake Biwa, one of the few ancient lakes in the world, harbors many coastal species that commonly inhabit seashores. The beach pea (Lathyrus japonicus) is a typical coastal species of this freshwater lake, and morphological and genetic differentiation between inland and coastal populations of this species have been reported. Inland and coastal habitats inflict distinct environmental stresses to plants, the latter imposing salt stress and high-light intensity, which leads to physiological differentiation. These abiotic stresses affect phenolic compounds, which play an important role in the response of plants to the toxic by-products of stress metabolism. We investigated physiological differentiation of phenolic compounds of the beach pea between inland and coastal habitats using high-performance liquid chromatography (HPLC) analysis. Flavonoid composition analyses revealed that patterns of flavonoid composition of inland populations at Lake Biwa were differentiated from those of coastal populations. All Lake Biwa individuals were fixed in the same flavonols glycosylated at 3- and 7-positions. In contrast, most coastal individuals contained flavonols glycosylated at 3-position alone, and these populations exhibited higher variation in flavonoid composition compared to among/within inland populations. Variation was likely lower in inland populations because of a bottleneck during landlocked periods, which is consistent with previous phylogeographic studies. A qualitative HPLC survey of flavonoid content revealed substantial variation among individuals regardless of locality. These results suggest that changes in the habitat environment may have led to beach pea acclimation via alteration of the quantity and quality of flavonoids.     

Reconstructing the diets of Greek Byzantine populations (6th-15th centuries AD) using carbon and nitrogen stable isotope ratios

Documentary evidence and artistic representations have traditionally served as the primary sources of information about Byzantine diet. According to these sources, Byzantine diet was based on grain (primarily wheat and barley), oil, and wine, supplemented with legumes, dairy products, meat, and marine resources. Here, we synthesize and compare the results of stable isotope ratio analyses of eight Greek Byzantine populations (6th-15th centuries AD) from throughout Greece. The δ(13) C and δ(15) N values are tightly clustered, suggesting that all of these populations likely consumed a broadly similar diet. Both inland and coastal Byzantine populations consumed an essentially land-based C(3) diet, significant amounts of animal protein, and possibly some C(4) plants, while no evidence of a general dependence on low-δ(15) N legumes was observed. One interesting result observed in the isotopic data is the evidence for the consumption of marine protein at both coastal sites (a reasonable expectation given their location) and for some individuals from inland sites. This pattern contrasts with previous isotopic studies mainly on prehistoric Greek populations, which have suggested that marine species contributed little, or not at all, to the diet. The possibility that fasting practices contributed to marine protein consumption in the period is discussed, as are possible parallels with published isotope data from western European medieval sites.     

Contrasting patterns of morphological variation with dietary preferences in Micropogonias furnieri: insights from stable‐isotope and digestive‐trait analyses

The dietary preferences of populations of whitemouth croaker Micropogonias furnieri, which commonly inhabit estuarine and oceanic environments of the south‐western Atlantic Ocean, were investigated using stable‐isotope analysis and digestive traits, and compared with previous genetic and morphometric surveys of this species. Isotopic and C:N‐derived data suggested that individuals from coastal lagoons are the most differentiated from the remaining localities surveyed. In contrast, the analysis of the digestive traits did not show the same differentiation pattern. The overall correlation between isotopic, molecular and morphological variations suggests that genetic and phenotypic differences among populations are accompanied by differential resource use, supporting the idea that selective forces could be playing an important role in population differentiation.     

Could coastal plants in western Amazonia be relicts of past marine incursions?

The rainforests of Amazonia comprise some of the most biologically diverse ecosystems on Earth. Despite this high biodiversity, little is known about how landscape changes that took place in deep history have affected the assembly of its species, and whether the impact of such changes on biodiversity can still be observed. Here, we present a hypothesis to explain our observation that plants typical of Neotropical coastal habitats also occur in western Amazonia, in some cases thousands of kilometres away from the coast. Evidence on their current distribution, dispersal biology and divergence times estimated from molecular phylogenies suggest that these plants may be the legacy of the large marine‐influenced embayment that dominated the area for millions of years in the Neogene. We hypothesize that coastal plants dispersed along the shores of this embayment and persisted as inland relicts after the marine incursion(s) retreated, probably with the aid of changes in soil conditions caused by the deposition of marine sediments. This dispersal corridor may also have facilitated the colonization of coastal environments by Amazonian lineages. These scenarios could imply an unexpected coastal source that has contributed to Amazonia's high floristic diversity and led to disjunct distributions across the Neotropics. We highlight the need for future studies and additional evidence to validate and shed further light on this potentially important pattern.     

Adaptive patterns of osmotic and ionic regulation, and the invasion of fresh water by the palaemonid shrimps

To evaluate trends in the osmoregulatory behavior of neotropical, palaemonid shrimps, we investigated osmotic and ionic regulatory patterns in five species of Palaemon or Macrobrachium. The species' life histories depend on saline water to differing degrees, their habitats ranging from the marine/intertidal (P. northropi), through estuaries (P. pandaliformis) to coastal, freshwater streams (M. olfersii, M. potiuna) and inland, continental river systems (M. brasiliense). Hemolymph osmolality, chloride, sodium and magnesium concentrations were measured in shrimps exposed to experimental media ranging from fresh water (<0.5 per thousand ) to concentrated seawater (42 per thousand ) for up to 10 days. The marine and estuarine Palaemon species exhibit well-developed hyper/hypo-osmotic, sodium and chloride regulatory capabilities in mid-range salinities, tending to hyperconform in low salinities. The freshwater Macrobrachium species show variable hyperosmotic, sodium and chloride regulatory capacities, tending to hypoconform or unable to survive at higher salinities. All species hyper-regulate magnesium in fresh water, but hyporegulate strongly in saline media. Palaemonids from the saline habitats show the strongest osmoregulatory capabilities, and fresh water may have been gradually invaded by ancestral species with similar regulatory capacity. However, this regulatory plasticity has been lost to varying degrees in extant freshwater species.     

Brain size, innovative propensity and migratory behaviour in temperate Palaearctic birds

The evolution of migration in birds remains an outstanding, unresolved question in evolutionary ecology. A particularly intriguing question is why individuals in some species have been selected to migrate, whereas in other species they have been selected to be sedentary. In this paper, we suggest that this diverging selection might partially result from differences among species in the behavioural flexibility of their responses to seasonal changes in the environment. This hypothesis is supported in a comparative analysis of Palaearctic passerines. First, resident species tend to rely more on innovative feeding behaviours in winter, when food is harder to find, than in other seasons. Second, species with larger brains, relative to their body size, and a higher propensity for innovative behaviours tend to be resident, while less flexible species tend to be migratory. Residence also appears to be less likely in species that occur in more northerly regions, exploit temporally available food sources, inhabit non-buffered habitats and have smaller bodies. Yet, the role of behavioural flexibility as a response to seasonal environments is largely independent of these other factors. Therefore, species with greater foraging flexibility seem to be able to cope with seasonal environments better, while less flexible species are forced to become migratory.     

Disease‐limited distributions? Contrasts in the prevalence of avian malaria in shorebird species using marine and freshwater habitats

Migratory shorebirds show strong dichotomies in habitat choice during both the breeding and nonbreeding season. Whereas High Arctic breeding species are restricted to coastal marine and saline habitats during the nonbreeding season, more southerly breeding species tend to use freshwater habitats away from coasts. It has been proposed that this co-variation in habitat use is a consequence of a single axis of adaptation to pathogens and parasites, which are hypothesized to be relatively scarce in High Arctic, marine, and saline habitats and relatively common at lower latitudes and in freshwater habitats. Here we examine this contrast by comparing the prevalence of avian malaria infections in shorebirds occupying different habitats. We used a PCR-based assay on 1319 individuals from 31 shorebird species sampled in the Arctic, in temperate Europe and in inland and marine habitats in West Africa. Infections mainly occurred in tropical wetlands, with the shorebirds in freshwater inland habitats having significantly higher prevalence of malaria than birds in marine coastal habitats. Infections were not found in birds migrating through Europe even though conspecifics did show infections in tropical Africa. Adults should resist infection better than juveniles, but showed higher malaria prevalence, suggesting that infection probability increases with cumulative exposure. We argue that exposure to vectors is the main factor explaining the habitat-related differences in malaria prevalence.     

Can stable isotopes be used to infer site fidelity of nekton in open coastal areas?

Stable isotope analysis has been applied to the investigation of movement in several species, including marine animals. However, its application to nekton living in open coastal areas is still very scarce. This study aims to test if stable isotope analysis can be used for this purpose over a much wider spatial scale than previously investigated. Stable isotope analysis was used to 1) investigate isotopic variation in shrimp and fish, in 11 sites, along a 160 km coastal stretch, to 2) determine the site fidelity of the individuals within each species, and to 3) test the relation between the body size of the individuals within each species, at each site and the percentage of isotopic deviants. Site fidelity was the highest for the intertidal fish Gobius paganellus and Coryphoblennius galerita, with 60% and 64% of individuals considered residents, respectively, and lowest for the demersal fish Diplodus vulgaris and Diplodus sargus with 23% and 33% of resident individuals, respectively. The percentage of isotopic deviants was not correlated with length in any species. Site fidelity was considerably higher than that previously found for other open coastal areas and similar to more structured environments, like coastal ponds. It was hypothesized that the complex tri-dimensional structure of the rocky reefs that occur in this area, often encompassing channels and tide pools, offers conditions favourable to high site fidelity. This study shows that stable isotopes can be used to infer nekton movement in wide open coastal areas.     

DIETARY STUDIES OF MARINE MAMMALS USING STABLE CARBON AND NITROGEN ISOTOPIC RATIOS OF TEETH

This study used naturally occurring carbon and nitrogen stable isotopes of teeth to study the diets of marine mammals. The isotopic ratios of nonchemically preserved teeth from eight species of marine mammals, representing 87 individuals that spanned the trophic continuum, were found to reflect nutritional sources. The δ¹³C signals distinguished animals that lived in waters dominated by different primary producers (e. g., seagrass, kelp, and phytoplankton), and δ¹⁵N values indicated the diet and trophic level of the species. This research suggests that isotopic signatures of teeth can be used in dietary studies to show differences and similarities among age classes, genders, geographic locations, and time periods.     

Prevalence of malaria and related haemosporidian parasites in two shorebird species with different winter habitat distribution

Parasites can have strong effects on host life-history and behaviour, and result in changes in host population dynamics and community structure. We applied a PCR-based technique and examined prevalence of malaria and related haemosporidian parasites in two arctic breeding shorebird species: the Semipalmated Sandpiper (Calidris pusilla) and the Pectoral Sandpiper (C. melanotos). During the non-breeding season, Semipalmated Sandpipers inhabit coastal marine habitats, whereas Pectoral Sandpipers are found in inland areas. In accordance with the hypothesis that the risk of parasite infection is higher in a species wintering in freshwater areas, we found Plasmodium sp. infection during the breeding season only in Pectoral Sandpipers, whereas Semipalmated Sandpipers were parasite free. However, even in Pectoral Sandpipers sampled in the arctic, prevalence of malaria parasites was very low (<3% of individuals, n = 114). Overall, three different Plasmodium sp. lineages were found, one of which has never been described before.     

Uniform diet in a diverse society. Revealing new dietary evidence of the Danish Roman Iron Age based on stable isotope analysis

A systematic dietary investigation during Danish Roman Iron Age (1‐375AD) is conducted by analyzing stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) in the collagen of human and animal bone. The human sample comprises 77 individuals from 10 burial sites. In addition 31 samples of mammals and fish were analyzed from same geographical area. The investigation characterizes the human diet among different social groupings and analyses dietary differences present between sex, age, and site phase groups. Diachronically, the study investigates the Roman influences that had an effect on social structure and subsistence economy in both the Early and Late Period. Geographically the locations are both inland and coastal. The isotopic data indicate extremely uniform diet both between and within population groups from Early and Late Roman periods and the data are consistent throughout the Roman Iron Age. Protein consumption was dominated by terrestrial animals with no differences among social status, age, sex, or time period, while terrestrial plant protein only seems to have contributed little in the diet. Furthermore, the consumption of marine or aquatic resources does not seem to have been important, even among the individuals living next to the coast. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

Foraging ecology of the endangered wood stork recorded in the stable isotope signature of feathers

Down feathers and regurgitant were collected from nestling wood storks (Mycteria americana) from two inland and two coastal breeding colonies in Georgia. The stable isotopic ratios of carbon (¹³C/¹²C) and nitrogen (¹⁵N/¹⁴N) in these materials were analyzed to gain insights into the natal origins of juvenile storks and the foraging activities of adults. Down feathers differed in '¹³C between inland and coastal colonies, having average isotopic values that reflected the sources of carbon fixed in biomass at the base of the food web. Feathers from the inland colonies differed between colonies in '¹⁵N, while those from the coastal colonies did not. These patterns primarily reflected the foraging activities of parent storks, with individuals capturing differing percentages of prey of distinct trophic status at each colony. Collectively, the carbon and nitrogen isotopic signatures of feather keratin were used to distinguish nestlings from each colony, except for instances where storks from different colonies foraged in common wetlands. The stable isotopic composition of food items in regurgitant was used to reconstruct the trophic structure of the ecosystems in which wood storks foraged. Predicted foraging activities based on the isotopic composition of keratin were generally consistent with the percentage of prey types (freshwater vs. saltwater and lower trophic level vs. upper trophic level consumer) observed in regurgitant, except for the coastal colony at St. Simons Island, where the '¹³C of feathers strongly suggested that freshwater prey were a significant component of the diet. This inconsistency was resolved by aerial tracking of adults during foraging excursions using a fixed-wing aircraft. Observed foraging activities supported interpretations based on the stable isotope content of feathers, suggesting that the latter provided a better record of overall foraging activity than regurgitant analysis alone. Observed foraging patterns were compared to the predictions of a statistical model that determined habitat utilization based on habitat availability using a geographic information system (GIS) database. Observed foraging activities and those predicted from feathers both suggested that some adult storks preferred to feed their young freshwater prey, even when saltwater resources were more accessible in the local environment. This conclusion supports the contention that wood stork populations are sensitive to changes in the distribution of freshwater habitats along the southeastern coastal plain of the United States.     

黄河口湿地有机碳来源及其对碳埋藏提升策略的启示

滨海湿地是地球上具有多种独特功能的生态系统,是地球上重要的碳库之一,其在全球碳循环中的作用在近年来越来越受到人们的重视。总结了用C/N、稳定碳同位素和生物标志物等方法追踪黄河口湿地有机碳来源的研究成果,并据此探讨了黄河口湿地的固碳提升策略。黄河口湿地是我国典型的滨海湿地,碳来源复杂,但各种示踪方法均表明有机碳的来源中陆源输入较海源输入优势明显,而且陆源输入以地表径流和植被为主,但海源输入从内陆向近海逐渐增强,碳的来源有明显的时空变化并且受到人类活动的强烈干扰。从有机质来源看,提升黄河口湿地的碳埋藏能力应该从合理调配河流淡水资源、保护植被、加快植物群落演替等方面入手。目前有机碳来源的研究还存在覆盖区域有限、碳源区分粗略、影响因子研究较少等问题,缺乏系统性,多限于观测,对机制的理解十分薄弱,因此难以对碳埋藏能力的提升提供定量化的指导。今后的研究要从以下几个方面加强:1)不同区域和不同环境条件之间的比较研究;2)探寻更具特异性的生物指标、优化数据模型,使来源区分更细致;3)不同来源有机质在沉积物中埋藏效率的对比研究;4)构建湿地碳埋藏能力评估体系,综合考虑各方面因素研发和集成能够最大限度提高滨海湿地碳埋藏能力的技术。     

Carbon isotopic composition of legumes with photosynthetic stems from mediterranean and desert habitats

The carbon isotopic compositions of leaves and stems of woody legumes growing in coastal mediterranean and inland desert sites in California were compared. The overall goal was to determine what factors were most associated with the carbon isotope composition of photosynthetic stems in these habitats. The carbon isotope signature (d13C) of photosynthetic stems was less negative than that of leaves on the same plants by an average of 1.51 ± 0.42 ;pp. The d13C of bark (cortical chlorenchyma and epidermis) was more negative than that of wood (vascular tissue and pith) from the same plant for all species studied on all dates. Desert woody legumes had a higher d13C (less negative) and a lower intercellular CO2 concentration (Ci ) (for both photosynthetic tissues) than that of woody legumes from mediterranean climate sites. Differences in the d13C of stems among sites could be entirely accounted for by differences among site air temperatures. Thus, the d13C composition of stems did not indicate a difference in whole-plant integrated water use efficiency (WUE) among sites. In contrast, stems on all plants had a lower stem Ci and a higher d13C than leaves on the same plant, indicating that photosynthetic stems improve long-term, whole-plant water use efficiency in a diversity of species.     

Body mass change and diet switch tracked by stable isotopes indicate time spent at a stopover site during autumn migration in dunlins Calidris alpina alpina

Birds may change their diet and foraging habitat during or after migration. Dunlins Calidris alpina alpina breed in the tundra of northern Europe and Russia where they feed exclusively on terrestrial prey. However, up to 80% of the flyway population uses the Wadden Sea as their first important staging site on the way to wintering grounds, feeding exclusively on marine prey. Adult birds migrate earlier than immatures and tend to fly non‐stop, whereas immatures may stage for at least a few days en route, mainly in the Baltic region. There they mostly feed on brackish water prey showing similar isotopic values compared to terrestrial prey. When they arrive in the Wadden Sea, dunlin body reserves are depleted and lower than those of individuals that have already staged for several days. We hypothesized that lighter individuals should retain a strong terrestrial isotopic blood signature, while heavier ones should show a stronger marine signature. We found a significant positive correlation between scaled mass index and carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes, reflecting the switch from terrestrial to marine prey during migration. A mixing model revealed differences in isotopic values between heavy and light adults and immatures, respectively, in relation to the isotopic prey signatures. Adults showed stronger marine signals compared with immatures, emphasizing the different modes of migration (i.e. a later departure in immatures) as well as the known spatial segregation of age classes in the Wadden Sea, i.e. adults use tidal flats distant from the shore while immatures use coastal areas influenced by terrestrial carbon sources. The results of this study demonstrate the value of scaled mass index in migratory birds as an indicator of time elapsed after diet switching following migration. Furthermore, this study extents the existing knowledge on the timing of dunlin migration by using an isotopic approach.     

The effect of physico-chemical parameters on speciation of trace metals insediments from inland and coastal waters of Ghana

The speciation of cadmium, lead, copper, zinc, manganese and iron into exchangeable, carbonate, reducible and organic bound fractions was studied in sediments from coastal and freshwater environments in Ghana. This was relevant as the species in which metals are stored within specific sediment components is important in determining their impact on the environment. For both coastal and inland sediments, a higher percentage of cadmium was associated with the more available exchangeable and carbonate fractions, while iron, zinc and manganese were mainly associated with the reducible and organic fractions. Lead and copper were found to have the greatest ability to form different species in the samples examined and were more evenly associated with all the fractions. The metals generally showed more ability to form different species in inland freshwaters than in coastal relatively saline waters. However, differences between inland and coastal waters were based more on whether the environments were oxidising or reducing than on whether they were fresh or saline. The metals may be divided into three groups of high mobility consisting of lead and copper; moderate mobility made up of cadmium, manganese and zinc; and low mobility, represented by iron.