Patterns of morphological variation in the Acacia species (Mimosaceae) of northern Sudan

KORDOFANI, M. & INGROUILLE, M., 1991. Patterns of morphological variation in the Acacia species (Mimosaceae) of northern Sudan. A numerical taxonomic review has been carried out on the morphology of northern Sudanese Acacia species. Fifty-one characters were scored from 12 species sampled at 12 sites. There is evidence of large scale population variation. Within a single site species are distinct but a comparison of plants between different sites may obscure species differences. Each species has a peculiar local variant in each sampled site, even when sites are separated by only a few kilometres. The possible significance of this pattern of variation is discussed. Species complexes are delineated and useful species diagnostics described.     

Systematic relationships within the genus Trichomanes sensu lato (Hymenophyllaceae, Filicopsida): cladistic analysis based on anatomical and morphological data

Systematics within the genus Trichomanes sensu lato (Hymenophyllaceae, Filicopsida) have continued to be controversial because of the difficulty in identifying homologies and informative characters within high morphological diversity. Systematic relationships are investigated in this study by using a cladistic approach with 31 anatomical and morphological characters from 20 taxa which correspond to the sections defined by Morton. The results broadly confirm Morton's four subgenera: Trichomanes, Didymoglossum, Pachychaetum and Achomanes. The monophyly of Pachychaetum remains fragile and the section Lacostea appears to be excluded from its traditional subgenus (Achomanes). In addition, by producing two major 'ecological' clades (terrestrial and epiphytic), the analysis shows that several selected characters appear to be strongly linked with the ecology which may have a significant influence on the topology.     

Genetic variation and the mating system in the rare Acacia sciophanes compared with its common sister species Acacia anfractuosa (Mimosaceae)

Acacia sciophanes is an extremely rare and Critically Endangered species known from two small populations separated by less than 7 km. Specifically we aimed to investigate whether rarity in A. sciophanes is associated with decreased levels of genetic variation and increased levels of selfing by comparing patterns of genetic variation and mating system parameters with its widespread and common sister species A. anfractuosa. Fourteen polymorphic allozyme loci were used to assess genetic diversity with four of these used in the estimation of mating system parameters. At the species level A. sciophanes has lower allelic richness, polymorphism, observed heterozygosity and gene diversity than A. anfractuosa and significantly lower levels of gene diversity at the population level. Both species have a mixed mating system but the largest population of A. sciophanes has lower levels of outcrossing, higher correlated paternity and increased bi-parental inbreeding compared with two A. anfractuosa populations. However, both correlated paternity and bi-parental inbreeding appear to be at least partly influenced by population size regardless of the species. We suggest that A. sciophanes is likely to be an intrinsically rare species and that in particular the lower levels of genetic diversity and increased selfing are a feature of a species that has the ability to persist in a few localised small populations. Despite recent extensive habitat destruction our comparative study provided no clear evidence that such events have contributed to the lower genetic diversity and increased selfing in A. sciophanes and we believe its ability to exist in small populations may not only be an important factor in its survival as a rare species but also indicates that it may be less susceptible to the impacts of habitat loss and fragmentation. The key to this species conservation will be the maintenance of suitable habitat, particularly through improved fire regimes and control of invasive weeds, that will allow the two small populations to continue to persist in extremely restricted areas of remnant vegetation.     

Morpho-anatomical features of the leaves of the mediterranean geophyteUrginea maritima (L) baker (Liliaceae)

The morpho-anatomy and histochemistry of the hysteranthous leaf ofUrginea maritima (L.) Baker and its adaptive strategies to the Mediterranean climate were investigated. The leaf ofU. maritima is 714 μm thick and possesses moderate specific leaf mass (8.564 mg cm^-2) and low tissue density (136.5 mg cm^-3). The epidermal cells are compactly arranged and covered with cuticle. The average density of stomata in lower epidermis is higher than that of the upper one. The mesophyll cells occupy 52.96% of the total volume of the leaf, while the mesophyll intercellular spaces and the air spaces occupy 30.41%. Idioblastic cells containing raphide bundles and different phenotypes of crystalloid inclusions, embedded in polysaccharides, occur in the lower side of the mesophyll. The presence of oil droplets and lipids is evident. Bundle sheath cells are hardly visible with no chloroplasts which are a pronounced C₃ plant character. Plastids containing protein crystalloid inclusions are abundant in the protophloem sieve elements.U. maritima, a deciduous plant, possesses leaves with mesophytic characters, in order to optimize its adaptation to the seasonal fluctuation of environmental conditions of the Mediterranean climate.     

Sexual Dimorphism of the Larynx of the Mongolian Gazelle (Procapra gutturosa Pallas, 1777) (Mammalia, Artiodactyla, Bovidae)

The larynges (except for the epiglottis) of two adult Mongolian gazelles, one male and one female, were dissected. This species is characterized by a pronounced sexual dimorphism of the larynx. Dimorphism with regard to the size of the entire larynx and of the thyroid cartilage is about 2:1 whereas the difference of mean body mass is about 1.3:1 between males and females. Unexpectedly, and in contrast to other bovids, the larynx of the male Mongolian gazelle has a paired lateral laryngeal ventricle. However, in contrast to horse, dog, pig and many primate species also possessing such a paired ventricle, its rostral opening in the Mongolian gazelle is situated lateral to the corniculate process of the arytenoid cartilage. The neck of the laryngeal ventricle is embraced by the bifurcated cuneiform process of the epiglottis. Despite the enlarged laryngeal cartilages, the vocal process of the male arytenoid cartilage is relatively shorter than that of the female. The male thyroarytenoid muscle is clearly separated into a rostral ventricular muscle and a caudal vocal muscle whereas the female's, as in other bovids, is almost uniform. The lateral sac of the two-chambered laryngeal ventricle in the male projects laterally between the ventricular and the vocal muscle. As in the domestic bovids and in many other artiodactyls the larynx of the male Mongolian gazelle is lacking any rostrally directed membraneous portion of the vocal fold. Instead, the thick and tough bow-like vocal fold projects caudally into the infraglottic cavity and is supported by a peculiar pan-like fibroelastic pad. This resilient element, situated medial to the bipartite thyroarytenoid muscle, might be a homologue of the vocal ligament, eventually including lateral portions of the elastic cone. A fibroelastic pad is absent in the female. The resilient floor of the laryngeal vestibulum, ventral to the fibroelastic pad, is rostrally and caudally subducted by tube-like spaces. Evolutionary enlargement of the male larynx, including the vocal folds, and of the caudal portions of the vocal tract may have shifted the fundamental and formant frequencies to a lower register. The paired lateral laryngeal ventricle might produce an amplitude increase of the vocalizations assisted by differential action of the bipartite thyroarytenoid muscle. In addition, the peculiar shape, size and tough consistency of the male vocal folds may, as in roaring felids, assist in producing high amplitude and low frequency vocalizations. Perhaps the biological role of the enlarged male larynx of Procapra gutturosa has evolved in relation to its mating system. In the rutting season, dominant males establish individual territories and maintain harems. During prolonged courtship prior to mating, these males perform an acoustic display uttering loud and guttural bellows. In addition, the bulging ventral neck region of males may serve as an optical attractant for the females. Thus, the evolution of the enlarged larynx of the male Mongolian gazelle may have been favoured by sexual selection.     

Multivariate analysis of morphological and anatomical characters of Calophyllum (Calophyllaceae) in South America

Calophyllum (Calophyllaceae), previously placed in Clusiaceae, is easily recognizable by its opposite entire leaves with close parallel venation alternating with resin canals. However, distinction between species has been difficult, because of infraspecific variation in tepal and stamen number and resemblance among species that share similar habitats. Here, I report the results of multivariate analyses of morphological and anatomical characters for Calophyllum in South America, and provide a taxonomic treatment for the genus in South America, the first since that of Vesque in 1893. Thirteen preliminary morphogroups were identified. Thirty‐two morphological characters of the leaf, flower and fruit from 401 specimens, and 17 anatomical leaf characters from 45 specimens were measured and analysed using principal component analyses (PCAs) and discriminant analyses (DAs). PCAs were used to find groups and DAs were used to validate those PCAs that were potential groups. Two main subgroups were identified in the general analysis. Subgroup M1 has terete stems and smaller leaves and flowers than subgroup M2, which, instead, has quadrangular stems. Only subgroup M2 showed distinctive clusters in regional and local analyses. Distinctive clusters and morphological and anatomical characters helped us to recognize four species in South America, including a new species, Calophyllum pubescens sp. nov. . In addition, a new species, Calophyllum mesoamericanum sp. nov. , is described from Central America. © 2013 The Linnean Society of London,     

Changes of Leaf Morphological, Anatomical Structure and Carbon Isotope Ratio with the Height of the Wangtian Tree （Parashorea chinensis） in Xishuangbanna, China

Leaf morphological and anatomical structure and carbon isotope ratio （δ^13C） change with increasing tree height. To determine how tree height affects leaf characteristics, we measured the leaf area, specific leaf mass （ratio of leaf mass to leaf area [LMA]）, thickness of the total leaf, cuticle, epidermis, palisade and sponge mesophyll, stomata traits and δ^13C at different heights of Parashorea chinensis with methods of light and scanning electron microscopy （SEM） and isotope-ratio mass spectrometry. The correlation and stepwise regression between tree height and leaf structure traits were carried out with SPSS software. The results showed that leaf structures and δ^13C differed significantly along the tree height gradient. The leaf area, thickness of sponge mesophyll and size of stomata decreased with increasing height, whereas the thickness of lamina, palisade mesophyll, epidermis, and cuticle, ratios of palisade to spongy thickness, density of stomata and vascular bundles, LMA and δ^13C increased with tree height. Tree height showed a significant relationship with all leaf indices and the most significant relationship was with epidermis thickness, leaf area, cuticle thickness, δ^13C. The δ^13C value showed a significantly positive relationship with LMA （R = 0.934）. Our results supported the hypothesis that the leaf structures exhibited more xeromorphic characteristics with the increasing gradient of tree height.     

The problematic systematic position of Ceratostratiotes Gregor (Hydrocharitaceae ?) – morphological, anatomical and biochemical comparison with Stratiotes L.

 The enigmatic fossil taxon Ceratostratiotes sinjanus (Kerner) Bužek has been considered as either a Hydrocharitaceae seed (monocot) or a Ceratophyllaceae fruit (dicot). The co-occurrence of seeds of Stratiotes kaltennordheimensis (Zenker) Keilhack (Hydrocharitaceae) and Ceratostratiotes in Early Miocene sediments in Langau (Lower Austria) enabled comparisons of morphological-anatomical features and lignin compositions, independent of diagenetic biases. The biochemistry of the Ceratostratiotes seed coat wall is not monocotyledon-like and is dissimilar to that of the co-occurring Stratiotes testae. In contrast, the Ceratostratiotes seed coat anatomy resembles that of Hydrocharitaceae genera with the micropyle and raphe being very similar to those in seeds of Stratiotes. Although the horizontal arrangement of the Ceratostratiotes spines is different from the longitudinal arrangement of the surface ridges in Stratiotes kaltennordheimensis and the spines in Blyxa (Hydrocharitaceae), the spine structures are very similar. A mixture of similarities and differences characterizes the morphological-anatomical features. Thus the systematic affinity of Ceratostratiotes still remains enigmatic. Received April 18, 2002; accepted October 18, 2002 Published online: February 4, 2003     

Relationships, classification and evolution of Scleranthus (Caryophyllaceae) as inferred from analysis of morphological characters

Study of floral anatomy, micromorphology, palynology and onotogeny has revealed new characters for phylogenetic analysis in the genus Scleranthus . Cladistic analysis of these characters, along with those previously available, suggests that the genus consists of Eurasian/Mediterranean and Australasian sister clades. Gynoecial morphology and development are closely similar in all species, suggesting the genus is monophyletic despite its disjunct northern and southern hemisphere distribution. Variation in pollen:ovule ratios and their implications for the evolution of Scleranthus species are also discussed and it is concluded that a range of breeding strategies intermediate between autogamy and xenogamy exists in the genus. Single-stamened species of Scleranthus are likely to be obligate autogams, despite their comparatively high pollen:ovule ratios in relation to autogamic species of other genera.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 15–29.     

Analysing diversity among Indian isolates of Anabaena (Nostocales, Cyanophyta) using morphological, physiological and biochemical characters

A set of 24 strains belonging to the genus Anabaena (Phylum Cyanobacteria), isolated from diverse geographic locations in India, were evaluated along with three International type strains of Anabaena (ATCC 29414, ATCC 29208 and ATCC 27899) for their morphological, physiological and biochemical diversity. The morphological dataset, consisting of 58 variants for 15 characters, and SDS-PAGE protein profiles comprising 17 polymorphic bands were utilized to differentiate the selected Anabaena strains and explore the patterns of diversity through cluster analysis. Physiological and biochemical characterization with respect to nitrogen fixation and accumulation of chlorophyll and phycobiliproteins led to the identification of some highly promising Anabaena strains for use as biofertilizers and source of pigments. The study highlighted the tremendous inter and intraspecific diversity within the Anabaena isolates and indicated the potential as well as constraints of the morphological and protein profiling datasets for unambiguous differentiation and analyses of diversity among the Anabaena strains.     

Individual variation in morphological, physiological, and biochemical features associated with calling in spring peepers (Pseudacris crucifer)

In an eastern North American tree frog, the spring peeper (Pseudacris crucifer), calling rate has been correlated with reproductive success in the field. To determine the sources of individual variation in calling rate in this species, I analyzed males calling at rates greater than and less than the chorus average throughout one breeding season. Compared to low-rate callers, high-rate callers were relatively larger, heavier, older, and in better body condition, and their muscles used in calling had higher activities of the enzymes citrate synthase and beta-hydroxyacyl-CoA dehydrogenase. This muscle profile is functionally matched by cardiovascular correlates, as indicated by the larger ventricles and higher blood hemoglobin concentrations in high-calling rate males. These cardiovascular features are much less developed in females and may result from the fact that females do not engage in vigorous calling behavior. In P. crucifier, a male's calling rate may function as an indicator of the presence of a suite of functionally interrelated traits responsible for the maintenance of this sexually selected display behavior.     

Acacia (Mimosoideae): composition and affinities of the series Pulchellae Bentham

The composition and affinities of the bipinnate Acacia series Pulchellae Bentham are examined in the light of evidence from studies of gross morphology, seedling morphology, pollen morphology and seed chemistry. Acacia mitchellii , the only non-Western Australian species, is atypical and should be relocated in section Vninervea Vassal. The remaining 27 species (the Pulchellae sensu lato ) comprise a coherent group of 21 species (the Pulchellae sensu stricto ) and six less closely related ones. These 27 species appear unrelated to series Botrycephalae Bentham. Some affinities exist with phyllodinous groups, especially series Uninerves and Continuae .     

Some morphometric,anatomical and biochemical characteristics of fruits and seeds of Onobrychis spp. in Italy

ABSTRACT

The fruits, seed coats and seed storage proteins of Onobrychis arenaria, O. montana, O. viciifolia, O. alba, O. supina and O. caput-galli were studied to examine the variability between and within species. The morphometric characteristics of the fruit had a high intraspecific variability which often exceeded that between species. Only the fruit of O. caput-galli had values for length, width, thickness and number of thorns which were almost always higher than those of the other species. The anatomical characteristics of the seed coats were extremely variable. The highest values of seed coat thickness were recorded in the diploid species. The palisade-like layer (or Malpighian cells) in O. caput-galli differed in size and morphology from that of the other species. The electrophoretic analysis revealed that the number and position of storage proteins varied between and within species.     

Effect of salinisation of soil on growth and macro- and micro-nutrient accumulation in seedlings of Acacia catechu (Mimosaceae)

The effects of salinisation of soil on Acacia catechu (Mimosaceae) were studied by means of emergence and growth of seedlings and pattern of mineral accumulation. A mixture of chlorides and sulphates of Na, K, Ca and Mg was added to the soil and salinity was maintained at 4.1, 6.3, 8.2,10.1 and 12.2 dSm⁻¹. A negative relationship between proportion of seed germination and salt concentration was obtained. Seedlings did not emerge when soil salinity exceeded 10.1 dSm⁻¹. Results suggested that this tree species is salt tolerant at the seed germination stage. Seedlings survived and grew up to soil salinity of 10.1 dSm⁻¹, which suggests that this species is salt tolerant at the seedling stage too. Elongation of stem and root was retarded by increasing salt stress. Among the tissues, young roots and stem were most tolerant to salt stress and were followed by old roots and leaves, successively. Leaf tissue exhibited maximum reduction in dry mass production in response to increasing salt stress. However, production of young roots and death of old roots were found to be continuous and plants apparently use this process as an avoidance mechanism to remove excess ions and delay onset of ion accumulation in this tissue. This phenomenon, designated “fine root turnover”, is of importance to the mechanisms of salt tolerance. Plants accumulated Na in roots and were able to regulate transfer of Na ions to leaves. Stem tissues were a barrier for translocation of Na from root to leaf. Moreover, K was affected in response to salinity; it rapidly decreased in root tissues with increased salinisation. Nitrogen content decreased in all tissues (leaf, stem and root) in response to low water treatment and salinisation of soil. Phosphorus content significantly decreased, while Ca increased in leaves as soil salinity increased. Changes in tissue and whole plant accumulation patterns of the other elements tested, as well as possible mechanisms for avoidance of Na toxicity in this tree species during salinisation, are discussed.     

Pollination of Aristolochia pallida Willd. (Aristolochiaceae) in the Mediterranean

A first study of the pollination biology of a Mediterranean Aristolochia species in its natural habitat is presented. In all, 183 flowers of Aristolochia pallida Willd. were investigated, which in total contained 73 arthropods, dominated by two groups of Diptera, black fungus gnats (Sciaridae representing 37%) and scuttle flies (Phoridae representing 19%), respectively. However, only Phoridae are regarded as potential pollinators, since pollen has been found exclusively on the body of these insects. All Phoridae belong to the genus Megaselia and are recognised as three morpho-species. The measurements of flower and insect dimensions suggest that size is an important constraint for successful pollination: (a) the insects must have a definitive size for being able to enter the flower and (b) must be able to get in touch with the pollen. Only very few insect groups found in A. pallida fulfil these size requirements. However, size alone is not a sufficient filter as too many fly species of the same size might be trapped but not function as pollinators. Instead, specific attraction is required as otherwise pollen is lost. Since all trapped Phoridae are males, a chemical attraction (pheromones) is proposed as an additional constraint. Since the flowers are protogynous, the record of Megaselia loaded with pollen found in a flower during its female stage proves that this insect must have had visited at least one different flower during its male stage before. Further on, this observation provides strong evidence that the flowers are cross-pollinated. All these factors indicate a highly specialised pollination of A. pallida by Megaselia species.     

Ontogenetic trends in the morphological features of main stem annual shoots of Pinus pinaster (Pinaceae)

Phase change refers to the transition between juvenile and adult vegetative phases. The study of trees throughout their entire life span requires retrospective analyses and validates the use of a chronosequence by sequencing observations at different and successive stages. The main axis growth pattern of 62 maritime pines (Pinus pinaster) selected in a chronosequence of three stands consisting of 8-, 22-, and 48-yr-old trees was analyzed retrospectively. Comparison of measured features (length, number of axillary products, reproductive organs) at common ages from the three stands supported the validity of using these data to form a continuous chronosequence. Endogenous trends in tree development are revealed free from variability due to annual growth conditions. Two main phases of development corresponding respectively to the juvenile vegetative and adult reproductive stages were identified, and the transition between both occurred in 9-yr-old trees. The relevance of these two phases and more generally the notion of phase changes are discussed in light of observed trends in the values of studied growth and branching parameters that may either show gradual variations (such as length of annual shoot) or a distinctive expression in one or the other phase (such as presence of female cones).     

Embryology of Eusideroxylon (Cryptocaryeae, Lauraceae) and character evolution in the family

Lauraceae are relatively well-known embryologically and embryological data are available for 23 of about 50 genera. In this paper we present the embryology of Eusideroxylon , an unstudied and key genus within Cryptocaryeae, which are positioned basally in the evolution of Lauraceae, and discuss the evolution of embryological characters in the family. Based on comparisons of over 50 characters, it was found that Eusideroxylon is consistent with Aspidostemon , the core Cryptocaryeae ( Beilschmiedia , Cryptocarya , Endiandra and Potameia ), Caryodaphnopsis and Cassytha in having a glandular anther tapetum. The core Cryptocaryeae further agrees with both Caryodaphnopsis and Cassytha in having an embryo sac protruding from the nucellus. In light of the phylogenetic trees available, both the glandular tapetum and the embryo sac protruding from the nucellus have evolved as homoplasies in Lauraceae, once each in a clade of Cryptocaryeae, and the Caryodaphnopsis and Cassytha clade, respectively. Such character-state distributions suggest that it is better to place both Caryodapnopsis and Cassytha in the same clade as the core Cryptocaryeae. Embryologically, Eusideroxylon appears to have an intermediate state between Hypodaphnis , a genus positioned basal-most in the family, and the core Cryptocaryeae. Supplementary data on the anther and seed of Hypodaphnis are also provided.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 187–201.     

Chlorophyll Catabolites in Senescent Leaves of the Plum Tree (Prunus domestica)

In cold extracts of senescent leaves of the plum tree (Prunus domestica ssp. domestica), six colorless non‐fluorescent chlorophyll catabolites (NCCs) were characterized, named Pd‐NCCs. In addition, several minor NCC fractions were tentatively classified. The structure of the most polar one of the NCCs, named Pd‐NCC‐32, featured an unprecedented twofold glycosidation pattern. Three of the NCCs are also functionalized at their 3²‐position by a glucopyranosyl group. In addition, two of these glycosidated NCCs carry a dihydroxyethyl group at their 18‐position. In the polar Pd‐NCC‐32, the latter group is further glycosidated at the terminal 18²‐position. Four other major Pd‐NCCs and one minor Pd‐NCC were identified with five NCCs from higher plants known to belong to the ‘epi’‐series. In addition, tentative structures were derived for two minor fractions, classified as yellow chlorophyll catabolites, which represented (formal) oxidation products of two of the observed Pd‐NCCs. The chlorophyll catabolites in leaves of plum feature the same basic structural pattern as those found in leaves of apple and pear trees.     

Development and microstructure of tooth histotypes in the blue shark,Prionace glauca (Carcharhiniformes: Carcharhinidae) and the great white shark,Carcharodon carcharias (Lamniformes: Lamnidae)

Elasmobranchs exhibit two distinct arrangements of mineralized tissues in the teeth that are known as orthodont and osteodont histotypes. Traditionally, it has been said that orthodont teeth maintain a pulp cavity throughout tooth development whereas osteodont teeth are filled with osteodentine and lack a pulp cavity when fully developed. We used light microscopy, scanning electron microscopy, and high‐resolution micro‐computed tomography to compare the structure and development of elasmobranch teeth representing the two histotypes. As an example of the orthodont histotype, we studied teeth of the blue shark, Prionace glauca (Carcharhiniformes: Carcharhinidae). For the osteodont histotype, we studied teeth of the great white shark, Carcharodon carcharias (Lamniformes: Lamnidae). We document similarities and differences in tooth development and the microstructure of tissues in these two species and review the history of definitions and interpretations of elasmobranch tooth histotypes. We discuss a possible correlation between tooth histotype and tooth replacement and review the history of histotype differentiation in sharks. We find that contrary to a long held misconception, there is no orthodentine in the osteodont teeth of C. carcharias. J. Morphol. 276:797–817, 2015. © 2015 Wiley Periodicals, Inc.     

Assessment of the state of the Japanese scallopMizuhopecten yessoensis in Alekseeva Bight (Peter the Great Bay, Sea of Japan) based on morphological and biochemical parameters

The results of an integrated examination of the state of the scallopMizuhopecten yessoensis in Alekseeva Bight (Peter the Great Bay, Sea of Japan) are presented. In mollusks of different ages, shell height was measured; in animals of commercial size (over 100 mm), some size and weight characteristics (annual increment of shell and adductor muscle and soft tissue weight) were determined. The morphology of the digestive gland and gills was studied. In the adductor muscle and digestive gland, the concentration of heavy metals (HMs) (Hg, Cu, Zn, Mn, Pb, Cd, Ni, Co, and Cr) was determined. In the digestive gland, metallothionein and reduced glutathione concentration was also determined, as was the activity of glutathione-dependent enzymes (glutathione peroxidase and glutathione reductase). In scallops collected outside Alekseeva Bight, the linear growth rate and adductor muscle weight were on average 1.3 and 1.7 times greater, respectively, than in those collected in the bight. In scallop organs, numerous histomorphological alterations were revealed: digestive cell vacuolization and hemocyte infiltration of the digestive gland, hyperplasia and vacuolization of the respiratory epithelium, and connective tissue hypertrophy in gill filaments. The biochemical parameters of scallops from Alekseeva Bight differed substantially from those of mollusks collected outside the bight. We conclude that one of the factors negatively affecting the state of theM. yessoensis population in Alekseeva Bight is the contamination of the bight with HMs, especially mercury. This is consistent with the results of chemical analysis of bottom sediments and tissues of two mytilid species,Modiolus kurilensis andCrenomytilus grayanus, specimens of which were collected in the bight together with the scallops [3].