Bottom-dwelling Animals Research Articles

Bottom fishery impact generates tracer peaks easily confused with bioturbation traces in marine sediments

Abstract. In the process of reworking sediments and thus shaping biogeochemical processes, marine bottom-dwelling animals are thought to play a pivotal role in many benthic environments. Bioturbation (particle reworking) includes the downward transport of particles into the sediment as a major process and is sometimes detected as subsurface maxima (peaks) of specific particulate substances (tracers). Here, we document the fact that subsurface peaks, such as those typically attributed to biological particle transport in sediments, may equally be generated by otter boards in bottom-trawling fishery. Boards can generate tracer peaks whereby they scoop sediment from the surface, flip it over, and deposit it onto the adjacent seafloor. These peaks are indistinguishable from those generated by benthic fauna burying surface material at sediment depth. We demonstrate this for the particle tracer chlorophyll a in silty sand from the western Baltic Sea with fauna that generally do not burrow deep in a global comparison. Our inability to distinguish the driving processes generating the peaks indicates limits to our understanding of the magnitude and spatial extent of bioturbation traces in this environment. It also poses a problem for the assessment of fishery resource use and benthic processes. However, based on natural fauna abundance, behavioral information, and fishery intensity data, we identify macrofauna and not otter boards as the dominant cause of peaks at the sites investigated here.

Elevated levels of per- and polyfluoroalkyl substances (PFAS) in freshwater benthic macroinvertebrates from the Hudson River Watershed

Per- and polyfluoroalkyl substances (PFAS) are contaminants of global concern due to their persistence and associated negative health effects. Considerable attention has been given to monitoring PFAS in the aquatic environment, however, few investigations have done so using freshwater benthic macroinvertebrates (BMIs). As these bottom-dwelling animals are known to bioconcentrate exogenous pollutants to a high degree, studying their PFAS levels may provide a more integrated view of PFAS contamination in the aquatic environment. In this study, BMIs, sediment, and surface water were collected from two streams in the Hudson River Watershed (one historically-impacted by PFAS) and analyzed for 44 PFAS using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Orbitrap high-resolution mass spectrometry (HRMS) was used to confirm the identities of quantitated analytes. Across all matrices, 17 analytes were detected with PFOA dominating in surface water and PFOS in sediment/BMIs. PFOS bioaccumulation factors (BAFs) were approximately one order of magnitude higher than those of PFOA and ranged from 857 to 5151 L kg−1 across different BMI taxa. While PFAS concentrations in surface water and sediment were not excessively high, elevated levels were still measured in most BMI taxa. This observation suggests that the extent of PFAS contamination in a local system may be severely underestimated if only surface water and sediment are used for monitoring. Moreover, these findings have relevance for human exposure assessment considering BMIs are the primary food source of many fish.

Organism functional traits and ecosystem supporting services – A novel approach to predict bioirrigation

Increasing anthropogenic activities on land and at sea underline the demand for easily applicable indices to effectively predict human mediated changes in ecosystem functioning. Here, we propose a novel bioirrigation index (IPc) that is based on body mass, abundance, burrow type, feeding type and injection pocket depth of bottom dwelling animals. The index was validated with combined field (in situ communities) and manipulative (single species) experiments. Results from both community and single-species experimental incubations indicate that IPc is able to predict the bioirrigation rate in different sediment types (mud, fine sand, sand). The trait-based index thus demonstrates robustness in the prediction of animal-mediated functional processes that support biogeochemical functions under variable environmental conditions. Accordingly, we argue that trait-based indices provide a useful tool for the quantitative prediction of ecosystem processes as effect traits provide a direct link to the behavioral mechanisms that drive ecosystem functioning.

Feeding biomechanics of Late Triassic metoposaurids (Amphibia: Temnospondyli): a 3D finite element analysis approach.

The Late Triassic freshwater ecosystems were occupied by different tetrapod groups including large-sized anamniotes, such as metoposaurids. Most members of this group of temnospondyls acquired gigantic sizes (up to 5 m long) with a nearly worldwide distribution. The paleoecology of metoposaurids is controversial; they have been historically considered passive, bottom-dwelling animals, waiting for prey on the bottom of rivers and lakes, or they have been suggested to be active mid-water feeders. The present study aims to expand upon the paleoecological interpretations of these animals using 3D finite element analyses (FEA). Skulls from two taxa, Metoposaurus krasiejowensis, a gigantic taxon from Europe, and Apachesaurus gregorii, a non-gigantic taxon from North America, were analyzed under different biomechanical scenarios. Both 3D models of the skulls were scaled to allow comparisons between them and reveal that the general stress distribution pattern found in both taxa is clearly similar in all scenarios. In light of our results, both previous hypotheses about the paleoecology of these animals can be partly merged: metoposaurids probably were ambush and active predators, but not the top predators of these aquatic environments. The FEA results demonstrate that they were particularly efficient at bilateral biting, and together with their characteristically anteropositioned orbits, optimal for an ambush strategy. Nonetheless, the results also show that these animals were capable of lateral strikes of the head, suggesting active hunting of prey. Regarding the important skull size differences between the taxa analyzed, our results suggest that the size reduction in the North American taxon could be related to drastic environmental changes or the increase of competitors. The size reduction might have helped them expand into new ecological niches, but they likely remained fully aquatic, as are all other metoposaurids.

綦江评价指标体系构建和健康评价研究

河流健康评价研究对河流环境的治理与保护工作具有重要的指导作用。本文采用基于层次分析法的综合评价方法，对长江一级支流重庆市綦江进行了河流健康评价研究。在确定了评价指标权重与指标标准特征值的前提下，尝试从水文水资源、水环境状况、水生生物状况、社会服务功能四个方面共13个指标，表征河流的健康状况。结果表明，綦江水体基本处于健康状态。13个评价指标中，生态流量满足程度、河流连通阻隔状况、纳污性能指数、大型底栖动物完整性指数、鱼类完整性指数得分相对较低。与此同时，由于綦江上水工建筑的兴建，阻断了鱼类洄游的路线，造成河段鱼类生态系统出现片段化现象，大型底栖动物完整性指数也受到影响。綦江上大多数水利工程还需要设置生态水量放水设施，另外綦江中段污染和人类活动的干扰稍微严重，化学需氧量和氨氮的排放量较大，需要进一步加强管理。 The study of river health assessment plays an important role in the management and protection of river environment. In this paper, a comprehensive evaluation method based on analytic hierarchy process (AHP) was used to study the health assessment of Qijiang River in Chongqing, the first-grade tributary of the Yangtze River. The weight of evaluation index and the characteristic value of the index standard had been determined. Meanwhile, 13 indicators from hydrology-water resources, water environment, aquatic condi-tions and social service functions had been used to characterize the health of the river. The results showed that the water body of Qijiang was basically in a state of health. In the 13 evaluation indexes, the ecological flow satisfaction degree, the river connectivity barrier status, the pollution index performance index, the index of the integrity of the benthic animal and the integrity index of the fish were relatively low. Mean-while, due to the construction of the Qijiang Shang Shui, blocking the route of migratory fish, fragmentation phenomenon appears in the river fish ecology system and large bottom dwelling animals’ complete index is also affected. Most of the water conservancy projects also should set ecological water drainage facilities; the middle pollution and human interference are slightly worse; emissions of COD and ammonia nitrogen are larger, which all need to further strengthen management.

The Tommotian phase of the Early Cambrian Agronomic Revolution in the carbonate mud environment of central Siberia

The profound ecological change of the marine benthos that eventually led to the almost complete destruction of the Precambrian matgrounds by benthic grazers and bioturbators (the agronomic revolution) was largely completed in the Tommotian. At that time, burrows produced by bottom-dwelling animals as shelters against predators were supplemented by burrowing for food by predators and sediment feeders. The limy mud ichnofauna of that age in Siberia was very different from the roughly coeval sand bottom faunas of Baltica. Although the exact zoological identity of the animals forming the infaunal Tommotian traces remains unknown, they probably mostly represent various kinds of early nemathelminthes. No apparent locomotion traces of mollusc origin have been encountered in the Early Cambrian, despite the abundant occurrence of skeletal fossils attributed to molluscs. Possibly the standard muscular foot, typical of modern molluscs, had not yet developed. Ichnotaxa represented are Teichichnus isp., Rhizocorallium isp., Chondrites isp., possibly the Buren ichnocomplex and others.

A BATCH STUDY OF PHOSPHATE ADSORPTION CHARACTERISTICS ON CLAY SOIL

The research has been carried out on Phosphate (p-Adsorption) on clay soil through batch adsorption techniques. Main objectives of this study are to study the physical properties of clay soils, detection of Phosphate removal by adsor bent as a function of contact time, adsorbent dosage and p H , to study sorption kinetics. The results of this study shows the optimum contact time, dosage and p for adsorption of Phosphate on clay soil reaching the equilibrium condition after 60 minutes with remov al efficiency of 86% and 1400 mg as optimum dosage. Higher adsorption of Phosphat e was observed at p H 9.0. The rate of adsorption of Phosphate obeys fir st order rate equation. The obtained results of the batch ex periments are best fit to Langmuir and Freundlich a dsorption isotherms. From the experimental analysis it is concluded that clay soi l shows good removal efficiency and can be used as good adsorbents. st century are waste disposal from various industries, municipal dumping in the urban areas and increased use of chemical fertilize rs, pesticides and irrigation water. The residues of fe rtilizers, pesticides and irrigation water created adverse imp act on soil and water bodies. The pollutants such as sewage and fertilizers contain nutrients as phosphates and nitrates. If th e nutrients are in excess level they over stimulate the growth of aquatic plants and algae. These excessive growths of algae and aquatic plants clogs the water ways, use up dissolved oxyge n as they decompose and block light to deeper water affecting the respiration ability of fish and other invertebrates that reside inside the water. Lakes, rivers and other water bod ies undergo Eutrophication an aging process in natural conditio n that slowly fills in the water body with sediment and or ganic matter. These sediments when enter water bodies fis h respiration becomes impaired, plant productivity an d water depth becomes reduced and aquatic organisms and their environment becomes suffocated. When the levels of oxygen drops below two-five parts per million many types o f fish and bottom dwelling animals cannot survive. When this occurs it leads to the disruptions in the food chain by killi ng aquatic organisms in large numbers. Oxygen demanding materials such as nitrogen and phosphorous are high in animal wastes and they often harbor pathogenic organisms. Hence s ome special attention must be given for budgeting of fe rtilizers; Phosphorous in high doses may be susceptible to dra in freely in the soil immediately followed by heavy rainfall causes some phosphorous losses through volatilization and leaching process. Thus once the ecosystem are contaminated by these elements they become a potential threat for many ye ars. Therefore it is of crucial importance to study the mutual influence of the different minerals in soil retenti on process whose migration ability of particular component in ground water is explained by the retardation factor(R).Far mers extensively follow the irrigation process due to av ailability of water from various sources, where phosphate polluti on is caused by the use of fertilizers and pesticides. Th us the main objective of this work is to study the leaching and retention of phosphate in the clay soil available in the area us ed for agricultural process, determining the maximum amount of phosphate adsorbed and to evaluate the potentials o f phosphate migrating through the soil during ground water percolation by using a set of batch experiments who se results are fitted to the equations given by Langmuir and F reundlich isotherms.

Effect of radioactive pollution on the biodiversity of marine benthic ecosystems of the Russian Arctic shelf

This study is the result of many years of research on the ecology of the marine benthos of Russian Arctic seas. We used samples collected at various locations from the Russian continental shelf during 1993–2009 as the basis of our study. Our main aim was to analyze the spatial distribution of taxonomic and quantitative characteristics of the meiobenthos (small bottom-dwelling animals, 0.1–3.0mm in size). Statistical analysis of the data revealed that the factors determining the spatial distribution of meiobenthic organisms under natural conditions, and conditions impacted upon by human activity, were salinity, water depth, hydrocarbons, heavy metals and radiocaesium volumetric activity. The possible use of the meiobenthos as a tool for environmental impact assessment is proposed and discussed on the level of higher taxa.

Sponge Identification Guide NAFO Area

Accurate reporting of sponges is increasingly important for mapping distributions and for the continued development of sustainable fisheries under the ecosystem approach. This Sponge Identification Guide is intended to help those on-board commercial and research fishing vessels to identify and record the various species of sponges likely to be commonly encountered in fishing trawls in the NRA. The guide is clear and simple to use, and will provide names to the majority of these bottom dwelling animals. The photographs are typically of caught specimens as seen on the deck.

Use of Sediment Risk and Ecological/Conservation Value for Strategic Management of Estuarine Environments: Sydney Estuary, Australia

Sediment mantling the floor of Sydney estuary contains a wide range of chemicals at highly elevated concentrations over extensive areas. Appropriate sediment management decisions are urgently required to prevent further degradation of sediment quality and to minimize resulting adverse ecological effects. The objective of the present work was to provide a systematic, estuary-wide assessment of sediment risk and ecological/conservation value throughout the harbor to guide sediment management decisions. Sediment risk is the likelihood of sediment chemistry causing adverse biological effects to bottom-dwelling animals and was conducted using national sediment quality guidelines (SQGs) for single contaminants and the mean SQG quotient approach to assess chemical mixtures. Sediment risk was negligible at the mouth of the estuary, but increased strongly landwards. The ecological/conservation value assessment was conducted to identify sites that warrant different levels of protection and was conducted using the value of ecological communities and priority waterway use. Consideration of these two parameters combined enabled the estuary to be prioritized for management attention. The prioritization and identification of appropriate management strategies were determined through the use of management matrices also based on sediment risk and ecological/conservation value. A computer package is being developed to provide managers with information on sediment risk, ecological/conservation value, the urgency and the type of management intervention required for any location in Sydney estuary, in real-time. This approach to estuarine management is unique and will greatly improve effective management of Sydney estuary, and other harbors in urgent need of management action and protection.

A New Stratified Aquatic Sampling Technique for Aquatic Vertebrates

ABSTRACT We developed a new type of passive-sampling minnow trap that enables aquatic sampling at depths of up to 70 cm without drowning obligate air-breathers. The trap demonstrated a heightened ability to capture bottom-dwelling animals that may otherwise be underrepresented by other trapping methodologies. The success rate of this new trap, relative to conventional minnow traps, seems to vary across wetlands and seasons. After 502 trap-nights with the new trap and 870 trap-nights with minnow traps at three wetlands, we present data for three species of permanently aquatic salamanders, seven species of aquatic snakes, and four species of fishes.

Phosphorus control is critical to mitigating eutrophication

The Midwest floods of 2008 added more than just water to the region's lakes, reservoirs, and rivers. Runoff from farms and towns carries a heavy load of silt, nutrients, and other pollutants. The nutrients trigger blooms of algae, which taint drinking water. Death and decay of the algae depletes oxygen, kills fish and bottom-dwelling animals, and thereby creates “dead zones” in the body of water. The syndrome of excessive nutrients, noxious algae, foul water, and dead zones—which ecologists call eutrophication—is depressingly familiar to those who depend on water from rich agricultural regions.

Long time-series monitoring of the ecosystem at Deception Island, Antarctica: description of instrumentation

A description of the oceanographic instrumentation developed and deployed at Deception Island, Antarctica during the period 9 March 1999 to 20 November 2000 as part of the ERUPT program is presented. This instrumentation includes (1) an autonomous weather station (Terrestrial station) to record daily conditions and ice-cover, (2) an underwater time-lapse camera/sediment trap array to photograph the abundance and movements of bottom-dwelling animals and collect sinking particulate matter, (3) an acoustic array to monitor movements of macrozooplankton and nekton, (4) an autonomous, vertically profiling pump sampler to capture and preserve plankton and nekton from discrete depths, (5) thermistor arrays to record water temperature at various depths, (6) an acoustic Doppler profiler to record current velocities at discrete depths, and (7) a piston-operated grab respirometer to measure sediment community oxygen consumption and recover sediments. The Terrestrial station and thermistor arrays, current meter and grab respirometer were the most successful instruments deployed, producing large data sets. The acoustic array produced some data of limited value, while the camera tripod and pump sampler produced no useful data due to technical and operational problems.

A Demonstration of Nitrogen Dynamics in Oxic & Hypoxic Soils & Sediments

Nitrogen is the fourth most abundant element in living organisms, and plays a central role in the architecture of nitrogen bases in DNA and amino acids in proteins. Nitrogen often limits plant growth in terrestrial ecosystems, which explains why nitrogen is the primary nutrient in agricultural and lawn fertilizers. Excessive fertilization with nitrogen can result in toxic concentrations of nitrate in ground water ( 100 ppm N-NO3) causing methemoglobinemia in human infants due to reduction of nitrate to nitrite in the infant’s digestive system, and subsequent oxidation of ferrous ions (Fe 2) to ferric ions (Fe 3) in hemoglobin (Mason 1996). Since ferric hemoglobin (methemoglobin) cannot carry oxygen, anemia results. Humans may also convert nitrate to nitrosamines which are potential carcinogens (Mason 1996). Although nitrogen is also a limiting nutrient in the open ocean, many estuaries receive excessive nitrate loads from agricultural and urban watersheds. Nitrate is the dominant pollutant in Chesapeake Bay, where it causes large algal blooms and subsequent hypoxia that can kill bottom dwelling animals (Horton & Eichbaum 1994). However, wetland soils and sediments are typically anoxic, and denitrification by bacteria transforms nitrate to nitrogen gas. Denitrification in wetlands is considered an ‘‘ecosystem service’’ which acts like a tertiary sewage treatment plant. The purpose of this field and laboratory exercise is to study the fate of nitrogen in soils and sediments under oxic and hypoxic conditions.

The mathematics of early diagenesis: From worms to waves

The changes that sediments undergo after deposition are collectively known as diagenesis. Diagenesis is not widely recognized as a source for mathematical ideas; however, the myriad processes responsible for these changes lead to a wide variety of mathematical models. In fact, most of the classical models and methods of applied mathematics emerge naturally from quantification of diagenesis. For example, small‐scale sediment mixing by bottom‐dwelling animals can be described by the diffusion equation; the dissolution of biogenic opal in sediments leads to sets of coupled, nonlinear, ordinary differential equations; and modeling organisms that eat at depth in the sediment and defecate at the surface suggests the one‐dimensional wave equation, while the effect of waves on pore waters is governed by the two‐ or three‐dimensional wave equation. Diagenetic modeling, however, is not restricted to classical methods. Diagenetic problems of concern to modern mathematics exist in abundance; these include free‐boundary problems that predict the depth of biological mixing or the penetration of O2 into sediments, algebraic‐differential equations that result from the fast‐reversible reactions that regulate pH in pore waters, inverse calculations of input functions (histories), and the determination of the optimum choice in a hierarchy of possible diagenetic models. This review highlights and explores these topics with the hope of encouraging further modeling and analysis of diagenetic phenomena.

Effects of local and distant contaminant sources: polychlorinated biphenyls and other organochlorines in bottom-dwelling animals from an Arctic estuary

Elevated concentrations of organochlorines in the tissues of large marine predators in the Canadian Arctic are well documented. This paper presents some of the first data on the composition and distribution of chlorinated organic compounds in some arctic coastal animals found at lower levels of the marine food chain. Organisms include bottom-dwelling invertebrates: clams (Mya truncata), mussels (Mytilus edulis), sea urchins (Strongylocentrotus droebachiensis) and fish: sculpins (Myoxocephalus quadricornis). The majority of samples were collected in the vicinity of Cambridge Bay, Northwest Territories (NWT), Canada; however, samples were also collected near another inhabited area (Hall Beach, NWT) and at a reference site (Wellington Bay, NWT). PCBs and other organochlorines typically originate in more industrialized parts of the northern hemisphere, enter the Arctic, and are subsequently biomagnified. In this study, differences in the PCB congener compositions and concentrations, as well as the relative concentrations of a large suite of organochlorines in biota, allowed the discrimination between local and distant PCB sources. Terrestrial runoff from southern Victoria Island, NWT, has resulted in localized elevation of PCBs and chlorinated pesticides in marine sediment and bottom-dwelling animals. The major inputs of PCBs to coastal waters within Cambridge Bay were derived from local sources (the hamlet dump and DEW Line site). In addition, transport from more distant sources via riverine input accounts for locally elevated concentrations of other organochlorines in upper Cambridge Bay. This process may also account for concentrations of all measured organochlorines that are higher in Wellington Bay than in Queen Maud Gulf. The high PCB concentrations in the whole tissue (excluding liver) or livers of four-horned sculpins in Cambridge Bay (up to 220 ng/g and 1950 ng/g, respectively) and, to a lesser extent, Wellington Bay (3.8 ng/g and 47 ng/g, respectively) reflect a strong tendency for biomagnification of PCBs in coastal benthic communities.

Hypoxic tolerance of marine benthic fauna

In stratified coastal marine waters hypoxia is a growing problem affecting bottom-dwelling animals Earlier studies suggest oxygen concentrations of about 2 m l l l (Rosenberg 1980) as the lower tolerance limit for many benthic species in coastal areas. We exposed several conspicuous infaunal species on the NE Atlantic continental shelf, contained within their sediment habitat, to gradually reduced oxygen concentrations. Tolerance to hypoxia for the 8 species examined was in the range of 0.5 to 1.0 m l l l (8 to 15 % saturation), which they could tolerate for several days to weeks. The ophiuroid Amphiura fihformis left its protected position in the sediment at an oxygen concentration of 0.85 ml1-I (13 % sat.), whereas A. chiajei emerged from the sediment at 0.54 m l l l (8 % sat.).

Enigmatic changes in the hydromedusan fauna of the northern Adriatic Sea

In many coastal and estuarine waters1,2, sensitive bottom-dwelling animals are threatened by depletion of the oxygen concentration in the near-bottom layer3–5, as a result of eutrophic conditions inshore. Persistent or occasional periods of low oxygen can reduce the number of benthic species, as has been reported for Chesapeake Bay6. Although it has been hypothesized6,7 that low oxygen concentration in the near-bottom layer extirpates those plankton species that have a bottom phase in their life cycles (meroplankton), there has been no direct evidence for this. We present here a comprehensive set of data which clearly demonstrates a strong correlation between oxygen depletion near the bottom and the disappearance of meroplanktonic hydromedusan species from the fauna of the northern Adriatic Sea. We believe that we have identified indicator species of oxygen deficiencies in marine ecosystems.

Increasing turtle strandings in the southeast United States: A complicating factor

Increased strandings of dead loggerhead sea turtles Caretta caretta on southeast US shores may be the result of increased fishing efficiency and improved recruitment of young turtles to the population. Possibly, the practice of discarding overboard large amounts of unwanted fish and biological material may provide a major energy resource for loggerhead sea turtles and crabs, which are also loggerhead food items. Our observations show that many dead loggerheads stranded on Cumberland Island had eaten man-caught food in addition to the expected diet of crabs and other bottom-dwelling animals. Consideration of alternative methods of handling the incidental fish catch while trawling for shrimp may be useful in reducing the problem of killing of sea turtles in shrimp trawls.

X-Ray Analysis of Sediment Regions and Transport of Sediment Particular Material on the Gill of the Fingernail Clam, Musculium Transversum

Fingernail clams are dominant bottom dwelling animals in some waters of the midwestern part of the U.S. These clams prefer big river habitats with a silt bottom where peak numbers may exceed 100,000/m2 as in Keokuk Pool, Mississippi R. In the mid 1950’s, fingernail clams disappeared from a 100-mile section of the Illinois R., a tributary of the Mississippi R., due to unknown causes. In order to determine if the unknown factor(s) in the Illinois R. are present in the bed of this river, a sediment core of material was obtained. This material was divided into four samples (A thru D, upper to lower region, respectively). Particle matter from each sample was characterized as to size(μm), mass(mg/1), and concentration(particles/1). The lateral cilia on the gill (Fig. 1) of the fingernail clam are primarily responsible for the transport of sediment particles over the lamellae. These cilia are under the control of the nervous system and as such can respond directly to adverse environmental stress factors. Therefore, gill preps were isolated and subsequent measurement of the effects of temperature on rate(mm/sec) of sediment transport of samples A thru D were determined from dorsal to ventral border of the gill. For x-ray analysis, mud samples were dried and mounted on C stubs, coated with C, and examined in a Cambridge IIA SEM fitted with an Ortec computer-based EDS system.