Marine molluscs and fish as biomarkers of pollution stress in littoral regions of the Red Sea, Mediterranean Sea and North Sea

The intensive development of industry and urban structures along the seashores of the world, as well as the immense increase in marine transportation and other activities, has resulted in the deposition of thousands of new chemicals and organic compounds, endangering the existence of organisms and ecosystems. The conventional single biomarker methods used in ecological assessment studies cannot provide an adequate base for environmental health assessment, management and sustainability planning. The present study uses a set of novel biochemical, physiological, cytogenetic and morphological methods to characterize the state of health of selected molluscs and fish along the shores of the German North Sea, as well as the Israeli Mediterranean and Red Sea. The methods include measurement of activity of multixenobiotic resistance-mediated transporter (MXRtr) and the system of active transport of organic anions (SATOA) as indicators of antixenobiotic defence; glutathione S-transferase (GST) activity as an indicator of biotransformation of xenobiotics; DNA unwinding as a marker of genotoxicity; micronucleus test for clastogenicity; levels of phagocytosis for immunotoxicity; cholinesterase (ChE) activity and level of catecholamines as indicators of neurotoxicity; permeability of external epithelia to anionic hydrophilic probe, intralysosomal accumulation of cationic amphiphilic probe and activity of non-specific esterases as indicators of cell/tissue viability. Complete histopathological examination was used for diagnostics of environmental pathology. The obtained data show that the activity of the defensive pumps, MXRtr and SATOA in the studied organisms was significantly higher in the surface epithelia of molluscs from a polluted site than that of the same species from control, unpolluted stations, providing clear evidence of response to stress. Enhanced frequency of DNA lesions (alkaline and acidic DNA unwinding) and micronucleus-containing cells was significantly higher in samples from polluted sites in comparison to those from the clean sites that exhibited genotoxic and clastogenic activity of the pollutants. In all the studied molluscs a negative correlation was found between the MXRtr levels of activity and the frequency of micronucleus-containing hemocytes. The expression of this was in accordance with the level of pollution. The complete histopathological examination demonstrates significantly higher frequencies of pathological alterations in organs of animals from polluted sites. A strong negative correlation was found between the frequency of these alterations and MXRtr activity in the same specimens. In addition to these parameters, a decrease in the viability was noted in molluscs from the polluted sites, but ChE activities remained similar at most sites. The methods applied in our study unmasked numerous early cryptic responses and negative alterations of health in populations of marine biota sampled from the polluted sites. This demonstrates that genotoxic, clastogenic and pathogenic xenobiotics are present and act in the studied sites and this knowledge can provide a reliable base for consideration for sustainable development. Received: 2 March 1999 / Received in revised form: 2 August 1999 / Accepted: 3 August 1999     

Correlations between chaetodontid fishes and coral communities of the Gulf of Aqaba (Red Sea)

Synopsis The relationships existing between the chaetodontid fishes and the surrounding coral communities were investigated in the Gulf of Aqaba. Quantitative data were analysed by a correspondence and a cluster analysis. The results demonstrated a similarity in the spatial distribution of both communities. Significant correlations were found between the density of chaetodontid fishes and the diversity of the coral community as well as the substratum coverage by the coral colonies. The density of exclusive coral browsers was also correlated to the abundance of branching colonies. Among the different genera of branching corals, correlations were significant only for the genusAcropora. These results suggested the existence of strong links between coral and chaetodontid fish assemblages.     

Long-term persistence of low coral cover and abundance on a disturbed coral reef flat in the northern Red Sea

Levels of coral cover and abundance on a coral reef flat in Eilat (Israeli Red Sea) were estimated in 2001 by surveying nineteen 10-m transects, and compared to the levels reported in the same area between 1966 and 1973. Lower values compared to 1966 levels are evident, and there has been only a modest recovery following a catastrophic low tide that killed a large proportion of the corals in 1970. Percent cover of soft and stony corals (16.1%) was less than half of that reported for 1969 (35%), when a sharp decrease in coral abundance had already been observed. The total number of soft and stony coral colonies observed was 300, compared to 541 in 1966. In contrast to 1966, when half of the transects surveyed contained more than 30 coral colonies, no transects with this number of corals were observed. The cover of seven of the most common stony coral species was 841 cm, which is twice the coral cover of that in 1973, but only 22% of the 1969 level. Millepora dichotoma, an abundant species before 1970, has almost disappeared, and the soft coral Litophyton, abundant in 1972, was not observed. Anthropogenic nutrient enrichment is apparently among the causes for the lack of coral recovery in the studied reef flat. Reefs located further away from sources of pollution have recovered quickly after natural and anthropogenic disturbances and have retained their coral abundance and diversity.     

Diversity and spatial pattern of coral communities in the Red Sea upper twilight zone

Summary This is the first study based on numerical analysis of the abundance of 11 scleractinian corals of depths at between 100–210 m in the Red Sea twilight zone. Two distinct coral communities were found: a Leptoseris fragilis community at a depth of 100–130 m (zone 1) and a Dendrophillia horsti community below 130 m (zone 2, 3). Population densities and coral coverage are very low; distribution of individuals is highly clumped. Highest observed densities on 100 m² were 2720 individuals for L. fraglis, 2720 for D. horsti and 2260 for Javania insignis. Calculated coverage rates were maximally 3.6% (L. fragilis), 0.08% (D. horsti) and 0.11% (J. insignis). L. fragilis, the only symbiont bearing coral, was very abundant. It has an unusual depth range for a photosynthesising coral. Coral density is only weakly correlated with hard bottom coverage. Species diversity with an average of 8 species is highest at 120–170 m and decreases in shallower and deeper water. The study depth range is a transient zone for coral distribution. It contains the upper distribution limits of a few deep sea corals and the lower ones of several shallower water species. Ahermatypic corals, collected at 160–170 m depth, were transplanted from their original depth to 159, 118, 70 and 40 m; after one year most species survived transplantation far beyond their upper distributional limits. The symbiotic L. fragilis, collected at 120 m, survived transplantation to deep water (159 m) as well as shallow zones (90, 70 and 40 m). The study demonstrates the feasibility of line-transect methods for coral community studies with a submersible.     

Coral communities and coral-bivalve associations in the northern Red Sea at Safaga,Egypt

Summary The reefs near Safaga, Egypt, are built mainly by coral species ofPorites andAcropora. These genera are in general important for the formation of coral communities and reef structures. WhileMontipora orPavona are also species rich, their mean colony size is too small for a substantial role in the build-up of carbonate mass. Yet as a host coral,Montipora is more important thanPorites; both may accommodate the pectinidPedum and certain species of mytilidLithophaga. Such associations appear to be typical for specific reef areas and to be correlated to the food supply of the bivalves. These findings can be used for an actuopaleontological interpretation of the fossil situation. In addition to the frequency of occurrence, factors such as the growth form, growth rate, skeletal density and lifespan of corals are essential in determining their share in reef construction.     

Importance of foraminifera for the formation and maintenance of a coral sand cay: Green Island, Australia

 CaCO₃ production by reef-building organisms on Green Island Reef in the Great Barrier Reef of Australia is estimated and compared with the contribution of benthic foraminifera to the sediment mass of the vegetated sand cay. Major constituents of the cay are benthic foraminifera (mainly Amphistegina lessonii, Baculogypsina sphaerulata, and Calcarina hispida), calcareous algae (Halimeda and coralline algae), hermatypic corals, and molluscs. Among these reef-building organisms, benthic foraminifera are the single most important contributor to the sediment mass of the island (ca. 30% of total sediments), although their production of CaCO₃ is smaller than other reef-building organisms. Water current measurements and sediment traps indicate that the velocity of the current around Green Island is suitable for transportation and deposition of foraminiferal tests. Abundant foraminifera presently live in association with algal turf on the shallow exposed reef flat, whose tests were accumulated by waves resulting in the formation and maintenance of the coral sand cay. Accepted: 30 June 1999     

A new species of the cardinalfish genus Gymnapogon (Perciformes, Apogonidae) from the Red Sea

 A new cardinalfish species, Gymnapogon melanogaster, is described from two specimens collected at night in the Gulf of Aqaba, Eilat, Israel. This species is characterized by having 9 dorsal and 8 anal fin soft rays; 14–15 pectoral fin rays; 2 + 11 gill rakers; a flat, bifurcated preopercular spine; a naked body without a papillae network; black pelvic fins; and a black stomach. It is similar to Gymnapogon vanderbilti (Fowler, 1938) that is known only from the Line Islands of the Central Pacific Ocean. Received: December 26, 2001 / Revised: June 10, 2002 / Accepted: June 24, 2002 Acknowledgments We thank D. Didier and M. Sabaj of the Academy of Natural Sciences, Philadelphia, for loans of and for taking data from type specimens; T.H. Fraser of the Mote Marine Laboratory, Sarasota, kindly provided data on type specimens. We are grateful to E. Heemstra of the South African Institute for Aquatic Biodiversity, Grahamstown, South Africa, for the artwork presented in this article and to A. Lerner of the Hebrew University, Jerusalem, for his assistance in collecting the specimens. Correspondence to:Ofer Gon     

Community structure of stony and soft corals on vertical unplanned artificial reefs in Eilat (Red Sea): comparison to natural reefs

In many reef ecosystems, artificial reefs (AR) have become permanent additions to the area, sustaining well-developed benthic communities. Long-term studies on the development of AR coral communities are scarce, and comparisons with their natural surroundings are limited. The present study describes the stony and soft coral community structure of unplanned vertical AR in Eilat (Red Sea) that have progressed beyond the initial successional phases, and compares these to the adjacent natural reefs (NR). Coral communities were characterized using belt transects, conducted on 34- and 14-year-old unplanned AR, and on two proximate NR. Stony corals were the major component in the NR, while soft corals, mainly Nephtheidae, accounted for up to 90% of the total living coverage in the AR. This was attributed to physical and biological features associated with the ARs vertical orientation, which was absent in the NR, and to the life history traits of these soft corals. Community differences between the two AR were related to structural stability and age. The results suggest that AR may increase local heterogeneity and space availability by adding novel habitats, increasing production and elevating species diversity in the surroundings.Communicated by Biological Editor H.R. Lasker     

Tidal impact on planktonic primary and bacterial production in the German Wadden Sea

 Tidal variation of biological parameters was studied at three anchor stations in selected inlet channels of the northern German Wadden Sea in May and July 1994. Concentrations of bacteria, chlorophyll a and suspended matter as well as primary and bacterial production were assessed over a period of 25 h in the surface and in the bottom water. Diurnal variation in primary production was found both under in situ light conditions and under constant illumination. Tidal turbulence caused the introduction of detritus, bacteria and pigments from the sediment into the water column. The impact of sediment resuspension was most evident in the bottom water, leading to tidally oscillating bacterial production rates which were high during high stream velocity and low during the slack times. Estimations of the areal daily phytoplankton production and corresponding bacterial carbon demands were unbalanced. Primary production accounted for only 25–45% of the total bacterial carbon requirement. This discrepancy is due to the shallow euphotic depth in the Wadden Sea, allowing net primary production only in the upper 2–3 m of the water column, while the relatively high levels of bacterial activity do not show a vertical decline. Assuming that the specific biological activities in the water columns over the tidal flats are similar to those found in the inlet channels, it was found that production processes dominate in shallow areas whereas decomposition processes dominate in the deep channels. Moreover, the predominance of heterotrophic processes in the inlet channels means that additional organic carbon sources must contribute to the heterotrophic metabolism in the deep parts of the Wadden Sea, and that the horizontal flux of material is important in this turbid mesotidal ecosystem. Received: 18 April 1998 / Accepted: 12 November 1998     

Spatial distribution of fifty ornamental fish species on coral reefs in the Red Sea and Gulf of Aden

The spatial distribution of 50 ornamental fish species from shallow water habitats on coral reefs were investigated using visual census techniques, between latitudes 11−29°N in the Red Sea, in Jordan, Egypt, Saudi Arabia, and Yemen, and in the adjacent Gulf of Aden in Djibouti. One hundred eighteen transects (each 100×5 m) were examined in 29 sites (3−8 sites per country). A total of 522,523 fish individuals were counted during this survey, with mean abundance of 4428.2 ± 87.26 individual per 500 m² transect. In terms of relative abundance (RA), the most abundant species were Blue green damselfish, Chromis viridis (RA=54.4%),followed bySea goldie, Pseudanthias squamipinnis (RA= 34.7), Whitetail dascyllus, Dascyllus aruanus (RA= 2.6%), Marginate dascyllus, Dascyllus marginatus (RA= 2.0),Red Sea eightline flasher Paracheilinus octotaenia (RA=1.0),andKlunzinger’s wrasse, Thalassoma rueppellii (0.7%). The highest number of species (S) per 500 m² transect was found on reefs at the latitude 20° in Saudi Arabia (S=21.8), and the lowest number of species was found at the latitude 15° in Djibouti (S=11.11). The highest mean abundance (8565.8) was found on reefs at latitude 20° in Saudi Arabia and the lowest mean abundance (230) was found on reefs at latitude 22°, also in Saudi Arabia. Whereas, the highest Shannon-Wiener Diversity Index was found in reefs at the latitude 22° (H`=2.4) and the lowest was found in reefs at the latitude 20° (H`=0.6). This study revealed marked differences in the structure of ornamental fish assemblages with latitudinal distribution. The data support the presence of two major biogeographic groups of fishes in the Red Sea and Gulf of Aden: the southern Red Sea and Gulf of Aden group and the group in the northern and central Red Sea. Strong correlations were found between live coral cover and the number of fish species, abundance and Shannon-Wiener Diversity indices, and the strength of these correlations varied among the reefs. A conclusion was done that environmental differences among the reefs and the habitats investigated were important components of abundance variations and species diversity of ornamental fish along latitudinal gradients in the Red Sea and the Gulf of Aden.     

Evaluation of Sequence Variation and Selection in the Bindin Locus of the Red Sea Urchin, Strongylocentrotus franciscanus

Recent evidence suggests that gamete recognition proteins may be subjected to directed evolutionary pressure that enhances sequence variability. We evaluated whether diversity enhancing selection is operating on a marine invertebrate fertilization protein by examining the intraspecific DNA sequence variation of a 273-base pair region located at the 5′ end of the sperm bindin locus in 134 adult red sea urchins (Strongylocentrotus franciscanus). Bindin is a sperm recognition protein that mediates species-specific gamete interactions in sea urchins. The region of the bindin locus examined was found to be polymorphic with 14 alleles. Mean pairwise comparison of the 14 alleles indicates moderate sequence diversity (p-distance = 1.06). No evidence of diversity enhancing selection was found. It was not possible to reject the null hypothesis that the sequence variation observed in S. franciscanus bindin is a result of neutral evolution. Statistical evaluation of expected proportions of replacement and silent nucleotide substitutions, observed versus expected proportions of radical replacement substitutions, and conformance to the McDonald and Kreitman test of neutral evolution all indicate that random mutation followed by genetic drift created the polymorphisms observed in bindin. Observed frequencies were also highly similar to results expected for a neutrally evolving locus, suggesting that the polymorphism observed in the 5′ region of S. franciscanus bindin is a result of neutral evolution. Received: 19 June 1998 / Accepted: 2 August 2000     

A seafloor crater in the German Bight and its effects on the benthos

 In 1963 a deep crater was formed about 65 m below sea level in the western part of the German Bight, due to a gas eruption caused by drilling carried out from the platform ’Mr. Louie’. The study area is situated in a sandy to muddy bottom area inhabited by an Amphiura filiformis association (sensu Salzwedel et al. 1985). The crater, sometimes called ’Figge-Maar’, functions as a sediment trap, concentrating particles and organisms from the water column, thus leading to extreme sedimentation rates of about 50 cm, on average, per year. Crater stations, compared with stations situated in the vicinity, show enrichments of juveniles. Echinoderms, especially the subsurface-dwelling heart urchin Echinocardium cordatum and ophiuroids are responsive to enrichment. Other species that are typical of the Amphiura filiformis association are shown to be unable to cope with the special conditions in the crater. Received: 12 June 1998 / Accepted:16 September 1998     

Policy plans and management measures to restore eelgrass (Zostera marina L.) in the Dutch Wadden Sea

The Dutch Wadden Sea has been changed dramatically over the last centuries by human activities like land reclamation and different forms of fishery. This has, amongst other things, led to changes in the number of biological communities. One of the changes was the near extinction of eelgrass (Zostera marina L.) in the Dutch Wadden Sea. The deterioration of the area led to policy plans in the late 1980s that aimed at restoring the original natural communities of which the eelgrass community was one. This paper presents a restoration strategy which contains a selection procedure for suitable transplantation sites. The selection procedure is based on factors such as sediment composition, exposure time, current velocity and wave action. These were combined in a GIS-based map integrating these factors. One important action in the restoration process is to increase the number of freshwater discharge points to meet the requirements of the brackish water community in general and the growing conditions for eelgrass in particular. Received: 27 October 1999 / Received in revised form: 3 February 2000 / Accepted: 3 February 2000     

Trace element levels in mollusks from clean and polluted coastal marine sites in the Mediterranean, Red and North Seas

The trace element contamination levels in mollusks were evaluated for different marine coastal sites in the Mediterranean (Israeli coast), Red (Israeli coast) and North (German coast) Seas. Three bivalve species (Mactra corallina, Donax sp, and Mytilus edulis) and two gastropod species (Patella sp.and Cellana rota) were sampled at polluted and relatively clean sites, and their soft tissue analyzed for Hg, Cd, Zn, Cu, Mn and Fe concentrations. Representative samples were screened for organic contaminants [(DDE), polychlorinated biphenyls PCBs and polycyclic aromatic hydrocarbons (PAHs)] which exhibited very low concentrations at all sites. In the Red Sea, the gastropod C. rota showed low levels of Hg (below detection limit) and similar Cd concentrations at all the examined sites, while other trace elements (Cu, Zn, Mn, Fe) were slightly enriched at the northern beach stations. Along the Mediterranean coast of Israel, Hg and Zn were enriched in two bivalves (M. corallina and Donax sp.) from Haifa Bay, both species undergoing a long-term decrease in Hg based on previous studies. Significant Cd and Zn enrichment was detected in Patella sp. from the Kishon River estuary at the southern part of Haifa Bay. In general, Patella sp. and Donax sp. specimens from Haifa Bay exhibited higher levels of Cd compared to other sites along the Israeli Mediterranean coast, attributed to the enrichment of Cd in suspended particulate matter. Along the German coast (North Sea) M. edulis exhibited higher concentrations of Hg and Cd at the Elbe and Eider estuaries, but with levels below those found in polluted sites elsewhere. Received: 25 February 1999 / Received in revised form: 22 April 1999 / Accepted: 30 April 1999     

Identification of sequence variations by PCR-RFLP and its application to the evaluation of cpDNA diversity in wild and cultivated soybeans

The diversity and maternal lineage in wild and cultivated soybeans have previously been assayed using restriction fragment length polymorphism (RFLP) and sequencing analyses of chloroplast DNA (cpDNA). Here we describe a method based on PCR-RFLP for the identification of nucleotides at four mutation sites in non-coding regions of cpDNA. Of the four sites, two were located in restriction enzyme sites and two were not. For the latter two sites, new primers were designed to artificially create restriction sites that spanned them. The PCR-RFLP method enabled us to identify nucleotides at each of the four mutation sites easily and reliably. Fifty-seven wild and sixty-seven cultivated soybeans of different origins and different cpDNA types (types I, II, and III) were assayed. All of the samples tested could be classified into four haplotypes. All of the type-I and -II accessions had the same nucleotides at each of the four mutation sites, while all of the type-III accessions, except for 3 wild ones, had nucleotides that were different from those of types I and II. A sequencing analysis revealed that the 3 wild accessions possessed other single-base variations in the non-coding regions of trnH-psbA and trnT-trnL. The results of this study suggest that the type-I and type-II chloroplast genomes form a group that is distinct from the type-III chloroplast genome. Received: 14 April 2000 / Accepted: 11 July 2000     

Bivalve distribution on coral carpets in the Northern Bay of Safaga (Red Sea, Egypt) and its relation to environmental parameters

Summary Bivalve assemblages on coral carpets in the Northern Bay of Safaga do not form distinct associations, but gradually shift in faunal composition. The taxonomic shift is accompanied by continuous variations in bivalve density and percentage of living individuals as well as by a change of coral associations and potential bivalve habitats. The gradual lateral change of associations is best documented byTridacna maxima and jewel box clams (Chamoidea) and is probably due to variations of the suspension load in the water column. High suspension loads in the water column are additionally indicated by ‘giant oysters’ (extremely large individuals ofHyotissa hyotis) and striking agglomerates ofLopha cristagalli. The vertical differentiation is best documented by the decrease of the zooxanthellateTridacna maxima and is probably due to the depth-dependent light penetration in the water column, which is attenuated in areas of high suspension load.     

Corals in a non-reef setting in the southern Arabian Gulf (Dubai, UAE): fauna and community structure in response to recurring mass mortality

 Reef coral communities in a non-reef setting on shallow, flat hardgrounds were quantitatively sampled in Dubai Emirate (UAE, Southern Arabian Gulf) before and after a coral mass mortality in 1996. The coral fauna consisted of 34 scleractinian species before and 27 after the event, which removed virtually all Acropora. No alcyonacea were recorded. Five community types were identified and characterized by the dominant species: (A) a sparse Porites lutea community in sandy areas, (B) a dense Acropora clathrata community in areas with little sand, (C) a faviid community in muddy areas, (D) a Siderastrea savignyana community in sandy areas, and (E) a Porites compressa community, which built a framework in sandy areas. These communities are comparable to those described from other areas of the Gulf, where a stable pattern of community differentiation appears to exist. The spatial distribution and dynamics of the coral communities appears to be strongly influenced by mass mortality events recurring every 15 to 20 y. A combination of extreme water temperatures and high sedimentation/turbidity appear to be the major cause of mortality. Accepted: 13 June 1998     

Evolutionary changes in sites and timing of actin gene expression in embryos of the direct- and indirect-developing sea urchins, Heliocidaris erythrogramma and H. tuberculata

 We describe an evolutionary comparison of expression of the actin gene families of two congeneric sea urchins. Heliocidaris tuberculata develops indirectly via a planktonic feeding pluteus that forms a juvenile rudiment after a long period of larval development. H. erythrogramma is a direct developer that initiates formation of a juvenile rudiment immediately following gastrulation. The developmental expression of each actin isoform of both species was determined by in situ hybridization. The observed expression patterns are compared with known expression patterns in a related indirect-developing sea urchin, Strongylocentrotus purpuratus. Comparisons reveal unexpected patterns of conserved and divergent expression. Cytoplasmic actin, CyIII, is expressed in the aboral ectoderm cells of the indirect developers, but is an unexpressed pseudogene in H. erythrogramma, which lacks aboral ectoderm. This change is correlated with developmental mode. Two CyII actins are expressed in S. purpuratus, and one in H. erythrogramma, but no CyII is expressed in H. tuberculata despite its great developmental similarity to S. purpuratus. CyI expression differs slightly between Heliocidaris and Strongylocentrotus with more ectodermal expression in Heliocidaris. Evolutionary changes in actin gene expression reflect both evolution of developmental mode as well as a surprising flexibility in gene expression within a developmental mode. Received: 27 July 1997 / Accepted: 30 December 1997     

Genetic investigation of contributions of embryo and endosperm genes to malt Kolbach index, alpha-amylase activity and wort nitrogen content in barley

 A genetic model is proposed for the analysis of embryo and endosperm effects as well as GE interaction effects. An investigation of three malting quality traits in grains of seven parents and their F₂s was undertaken in a half-diallel cross of barley (Hordeum distichum L.) over 2 years. The results indicated that the malt Kolbach index (KI), alpha-amylase activity (αAA) and wort soluble nitrogen (Wort-N) are controlled by both embryo genetic effects and endosperm genetic effects. Variance of the endosperm additive effects was obviously larger than that of the embryo additive effects. In the contribution of the embryo genetic effects to variation in malt αAA and Wort-N, the dominance effects were considerably larger than the additive effects. The endosperm dominance effects constituted a major part of the total genetic effect on the KI. Significant endosperm GE interactions were also detected in the malt traits concerned. Endosperm general heritability (h ² _e ) tended to be larger than interaction heritability (h ² _oE or h ² _eE ) for all the traits. Endosperm heterosis was observed to be significantly positive for αAA but negative for Wort-N in the F₂ seed generation. Prediction of main gene effects for seven parents showed that ‘Ganmu 2’ and ‘Supi1’ were suitable parental varieties for malt αAA and Wort-N improvement. Our genetic model for malting quality traits and its application in breeding are discussed. Received: 5 August 1997 / Accepted: 11 September 1997