Survival Of Invertebrates Research Articles

Effects of zebra mussels on food webs: interactions with juvenile bluegill and water residence time

We evaluated how water residence time mediated the impact of zebramussels Dreissena polymorpha and bluegill sunfish Lepomis macrochirus on experimental food webs established in1100-l outdoor mesocosms. Water residence time was manipulated asa surrogate for seston resupply – a critical variable affectinggrowth and survival of suspension-feeding invertebrates. We used a2×2×2 factorial experimental design witheight treatment combinations (3 replicates/treatment) including thepresence or absence of Dreissena (2000 per m2), juvenilebluegill (40 per mesocosm), and short (1100 l per d) or long (220 lper d) water residence time. Measures of seston concentration(chlorophyll a, turbidity and suspended solids) were greaterin the short- compared to long water-residence mesocosms, butintermediate in short water-residence mesocosms containing Dreissena. Abundance of rotifers (Keratella and Polyarthra) was reduced in Dreissena mesocosms and elevatedin short residence time mesocosms. Cladocera abundance, in general,was unaffected by the presence of Dreissena; densities werehigher in short-residence time mesocosms, and reduced in thepresence of Lepomis. The growth of juvenile Lepomiswere unaffected by Dreissena because of abundant benthicfood. The final total mass of Dreissena was significantlygreater in short- than long-residence mesocosms. Impacts of Dreissena on planktonic food webs may not only depend on thedensity of zebra mussels but also on the residence time of thesurrounding water and the resupply of seston.

Anoxic or aerial survival of bivalves and other euryoxic invertebrates as a useful response to environmental stress—A comprehensive review

Laboratory and field studies have demonstrated the applicability of anoxic/aerial survival as an early warning indicator of contaminant induced stress. The effects of xenobiotics, including heavy metals, organometals and organics as well as contaminated field sediments have been investigated. The use of this physiological response is rapid, easily quantified and inexpensive. In most studies bivalve molluscs were investigated, the sea mussel Mytilus edulis L. being the favourite species. The different approaches used by various researchers, as reported in the literature, demonstrate the necessity for these experiments to be standardized. When estimating the mortality rate in a closed system or by aerial exposure, the cause of death may not be an indication of anoxia tolerance, but may be an artifact due to the development of microorganisms. Therefore the use of a flow-through system is suggested in cases where the duration of a test exceeds 1 week. When the response is used for the acute assessment of water quality a closed system may be used at low temperatures in combination with an organism with a relatively low anoxia tolerance (e.g., crustaceans). Various reasons why anoxic tolerance may be reduced by toxicants are proposed. Depletion of fuel reserves involved in anaerobic metabolism and intoxication by fermentative products may already commence during chronic exposure to contaminants, and/or the anaerobic energy metabolism may be disturbed. In general there is elevated catabolic activity during anoxic exposure, especially pyruvate derivatives are prominent end products in muscle tissue of contaminant exposed groups. comp biochem physiol 113C, 299–312, 1996.

Landscape Ecology and the Marine Environment: How Spatial Configuration of Seagrass Habitat Influences Growth and Survival of the Bay Scallop

Landscape ecology includes the study of the effects of spatial patterning of habitats on biotic and abiotic processes. Seagrass beds occur in a variety of spatial configurations providing a model system to test how spatial patterning of habitats influences ecological processes. We established four replicate plots over very patchy (22% cover), patchy (70% cover), and continuous (97% cover) seagrass beds so that each plot contained approximately 100 m 2 of vegetated bottom. Fifty individually marked scallops were placed within the seagrass in each plot and their survivorship monitored over three replicate 24-h periods, and growth and survival monitored over an additional four-week period. There was no pattern in survivorship with differences in habitat configuration over the first three 24-h of the experiment. By four weeks, more scallops were lost to predation in the very patchy seagrass beds than in the patchy or continuous beds. There was a non-significant trend for increased growth of juvenile scallops with increased patchiness of the seagrass habitat. Vegetation characteristics such as shoot density, biomass, and blade length, which have been shown to affect survival of seagrass-associated invertebrates, were not significantly different among seagrass beds with different spatial configurations. Our results demonstrate that spatial patterning of the habitat, independent of structural characteristics of the seagrass, can alter rates of predation on seagrass inhabitants. This implies that habitat utilization and/or foraging strategies of predators change with the spatial patterning of the vegetation and that very patchy seagrass beds may provide habitats where transfer of secondary production to higher trophic levels is great

Acute toxicity and hazard assessment of Rodeo�, X-77 Spreader�, and Chem-Trol� to aquatic invertebrates

The herbicide Rodeo® provides waterfowl managers with an effective chemical tool for creating open water habitats in wetlands if its use does not adversely affect native invertebrate communities. The survival of caged Chironomus spp. (midge), Hyalella azteca (amphipod), Stagnicola elodes (pond snail), and Nephelopsis obscura (leech) was assessed in prairie pothole wetlands treated by air with a tank mixture of Rodeo®, the surfactant X-77 Spreader®, and the drift retardant Chem-Trol® at a rate recommended for controlling cattails. Laboratory studies were then conducted to determine the acute toxicities of Rodeo®, X-77 Spreader®, and Chem-Trol®, individually and in simulated tank mixtures, to the same invertebrates and to Daphnia magna in reconstituted water representative of these wetlands. There was no difference in the survival of caged invertebrates between treated and reference wetlands after 21 days. Based on nominal concentrations of the formulations, X-77 Spreader® (LC50s=2.0–14.1 mg/L) was about 83–136 times more toxic than Rodeo® (LC50s=218–1216 mg/L) to aquatic invertebrates. Chem-Trol® killed ≤10% of the animals at 10,000 mg/L and ≤50% of the animals at 28,000 mg/L. Daphnia magna were more sensitive than the other species to X-77 Spreader®, Rodeo®, and the simulated Rodeo® tank mixture (RTM). The joint toxic action of the RTM was additive for amphipods and midges, greater than additive for leeches, and was less than additive for daphnids. X-77 Spreader® was the major toxic component in the RTM. Binary mixtures of X-77 Spreader®, Rodeo®, and Chem-Trol® at tank mixture and equitoxic ratios also showed additive toxicity to amphipods. The use of Rodeo® (applied as a tank mixture with X-77 Spreader® and Chem-Trol®) as a management tool in wetlands does not pose an acute hazard to native aquatic invertebrates because the concentrations of Rodeo®, X-77 Spreader®, and Chem-Trol® found to be acutely toxic to these invertebrates were much higher than their expected or measured concentrations in water from wetlands treated with the RTM.

The scientific management of temperate communities for conservation. The 31st symposium of the British Ecological Society, Southampton, 1989: I. F. Spellerberg, F. B. Goldsmith & M. G. Morris, (Blackwell Scientific, for British Ecological Society), ISBN (hardback) 0 632 02976 5, (paperback) 0 632 03186 7, price £45.00, £26.50, 1991, 566 pp, indexes.

In this review, we discuss the role of hedgerow structure and condition in determining the value of hedgerow habitat for biodiversity conservation within an agricultural context, to inform and evaluate hedgerow management decisions and policy. Through a systematic literature review, narrative synthesis and vote counting, key structural condition indicators were identified for a range of conservation priority taxa. Abundance, survival or fecundity of ground vegetation, birds, mammals and invertebrates were affected by height, width, woody biomass, foliar quality and quantity, and gappiness of hedgerows. Although general patterns may not occur, a response to a particular structural feature can vary both within and between taxonomic groups, many responses are synergistic and interdependent. In conclusion, the definition of a “good quality” hedgerow for biodiversity conservation should be expanded to include all those key structural features which are important across taxa. Furthermore, the importance of heterogeneity in hedgerow structural condition is highlighted, where no fixed set of hedgerow characteristics were found to benefit all taxa. If uniform hedgerow management is overprescribed, as has been the tendency with some agri-environment schemes, some species (including those of conservation concern) are likely to be adversely affected by a loss of suitable habitat or resource decline.

Analysis and interpretation of the recruit-settler relationship

There is considerable interest in the early survival of benthic invertebrates but existing analyses of relationships between settlement and recruitment have some interpretational and methodological flaws. We re-analysed published data for two species to illustrate these problems. We found, contrary to the conclusions of other workers, that early survival is enhanced at greater densities of settlers. We suggest that the relationship between survival and density of settlers be further studied to test the generality of this conclusion.

Ecological mechanisms important for the biotic changes in acidified Lakes in Scandinavia

We describe some mechanisms behind the biotic changes in acidified lakes in Scandinavia. Besides direct effects, such as reduced reproduction or survival of fish and invertebrates due to low pH or exposure to toxic metals, we emphasize the importance of indirect effects. Mechanisms involved are of an ecological character; such as a shift of top predatores from fish to invertebrates and a reduced decomposition rate due to decreased abundance of detrivores, as well as feed-back effects on the abiotic environment; such as reduced productivity and turnover rate of nutrients and an increase in water transparency. We include the aspects of how bird species in aquatic habitats may be indirectly affected.

Bioavailability and toxicity of metals leached from lead-mine tailings to aquatic invertebrates

Erosion and leaching of abandoned deposits of lead-mine tailings in southeast Missouri have resulted in the heavy metal contamination of surface waters, sediments and aquatic biota. We examined how cover materials added to stabilize tailings deposits might influence the mobilization of metals in mine tailings leachates by monitoring metal bioaccumulation and toxic effects in aquatic invertebrates (Orconectes nais, Hexagenia limbata and Chironomus riparius) exposed to leachates from test plots of tailings that had been given various cover treatments. Bioaccumulation of lead and cadmium increased significantly, and survival, growth and development were impaired in one or more invertebrate taxa during chronic (10–120 d) exposures to leachates from cover treatments of vegetation and organic mulches. Metal bioaccumulation and toxicity were greatest in a maple leaf cover treatment. Leachate from the leaf treatment had high metal concentrations because of the formation of metal/organic complexes. Lesser responses were observed in treatments of seed + fertilizer, bluegrass sod and dried sewage sludge, all of which resulted in the establishment of varying amounts of vegetative cover on the tailings. Bioaccumulation of lead, but not cadmium, was significantly correlated with the dissolved metal concentrations in the leachates. Toxic effects on invertebrate survival, growth and development were significantly correlated with the metal concentrations in leachate samples and, for lead, with body burdens in invertebrates. The results indicated that leachates from mine tailings deposits can adversely affect aquatic invertebrates, and that cover materials that release organic complexing agents can increase the mobilization of toxic metals in leachates. Vegetative cover would probably reduce future runoff and erosion from tailings deposits, but conditions similar to those in this study may favor the mobilization of metals from tailings already present in riparian habitats and stream sediments.

Invertebrate survey of offshore islands in relation to potential food sources for the little spotted kiwi,Apteryx oweni(Aves: Apterygidae)

An invertebrate survey of forest on Kapiti, Blumine, Long, Motuara, Pickersgill, and Red Mercury Islands showed that the same major invertebrate groups were present on all the islands. The same groups are also present in mainland broadleaf-podocarp forest of the Orongorongo Valley, near Wellington. The invertebrates eaten by the little spotted kiwi (Apteryx oweni Gould) on Kapiti Island were also found in reasonable numbers on some of the other offshore islands. The relationship between invertebrates and their predators was examined; habitat diversity seems important for the survival of larger invertebrates in the presence of mammalian predators.

Growth and Reproduction of Convoluta Roscoffensis Containing Different Naturally Occurring Algal Symbionts

INTRODUCTIONA common characteristic of alga-invertebrate symbioses is their specificity; in general, a given symbiotic invertebrate species forms a stable association with just one species or genus of alga. One approach to examine the basis and significance of the specificity is to compare the performance (i.e. survival, growth and reproduction) of invertebrates experimentally infected with a range of algae. To date, such investigations have been made almost exclusively with algae which do not naturally form an association with the host species (e.g. Schoenberg & Trench, 1980; Mews & Smith, 1982; Douglas, 1983), and the relevance of the conclusions to the natural situation is not always clear.

Effects of coal liquid water-soluble fractions on growth and survival of four aquatic organisms

Toxicities of water soluble fractions (WSF) derived from a fresh and a water-leached solvent-refined coal (SRC II) material were compared by observing freshwater organism response to chronic exposure. Concentrations, relative distributions, and loss over time of phenols and aromatic hydrocarbons differed between aqueous extracts derived from fresh and leached SRC II material. Readily water-soluble phenols predominated in initial WSFs; higher molecular weight compounds with relatively lower solubility predominated in leached WSFs. Suppression of growth, reproduction and survival of invertebrates,Chironomus tentans, Tanytarsus dissimilis, andDaphnia magna and the algaeSelenastrum capricornutum, were observed at concentrations ranging from 0.02 to 0.42% of WSFs derived from fresh SRC II liquid and 0.80 to 3.95% of WSFs derived from leached SRC II material. Alga populations were the least sensitive to WSFs generated from the coal liquid. Based on equal concentrations of carbon or phenols, solutions derived from leached SRC II liquids were usually more toxic to test species. Data suggest that tests of potential long-term effects of complex materials must be designed and interpreted on the basis of organism exposure to compounds most likely to persist in the environment.

Vertical migration and mortality of benthos in dredged material: Part III—polychaeta

The survival of benthic invertebrates from dredging and disposal activities is a major environmental concern in such projects. The purpose of the research described in this paper was to determine the ability of benthos (polychaetes, Scoloplos fragilis and Nereis succinea) to migrate vertically in natural and exotic sediments and to determine the survival of benthos when exposed to particular amounts of simulated dredged material. Mortalities generally increased with increased sediment depth, exotic sediment and burial time. Temperature also affected vertical migration and mortalities. These experiments, together with other experiments conducted by us and other workers, indicate that polychaetes in particular, and benthos in general, can survive dredging and disposal projects. Under certain conditions several major taxa (polychaetes, molluscs, crustaceans) can be expected to successfully recolonise disposal sites by vertical migration.

Vertical migration and mortality of benthos in dredged material: Part II—crustacea

A major concern in dredging and disposal projects is the effect of burial on the survival of benthic invertebrates. The purpose of the research described in this paper was to determine the ability of benthos (mud crab, Neopanope sayi; haustoriid amphipod, Parahaustorius longimerus) to migrate vertically in natural and exotic sediments and to determine the survival of benthos when exposed to particular amounts of simulated dredged material. Mortalities generally increased with increased sediment depth, burial time and exotic sediment type. Temperature also affected vertical migration and mortalities. As a taxonomic group, crustaceans show considerable virtuosity in burrowing. Even though N. sayi and P. longimerus cannot be included among the deepest crustacean burrowers, their performance in laboratory experiments indicates that they may be capable of recolonisation of disposal sites under certain conditions.

Vertical migration and mortality of benthos in dredged material—part I: Mollusca

Benthic invertebrates have many characteristics which make them prime candidates for burial studies in dredged material. A major concern in dredging and disposal projects is the effect of burial on the survival of benthic invertebrates. The purpose of the research reported in this paper was to determine the ability of estuarine benthos—in particular three species of molluscs ( Mercenaria mercenaria, Nucula proxima and Ilyanassa obsoleta)—to migrate vertically in natural and exotic sediments and to determine the survival of benthos when exposed to particular amounts of simulated dredged material. Mortalities generally increased with increased sediment depth, with increased burial time and with overlying sediments whose particle size distribution differed from that of the species native sediment. Temperature affected mortalities and vertical migration. It was concluded that vertical migration is a viable process which can significantly affect rehabilitation of a dredged disposal area. Under certain conditions, vertical migration should be considered, together with larval settling and immigration from outside impacted areas, as a mechanism of recruiting a dredgedump site.

Some aspects of recolonization of coral rocks in Eilat (Gulf of Aqaba) by fish populations after poisoning

As a result of an accident, a limited strip of the coast of Eilat (Gulf of Aqaba, Red-Sea) was affected by poison that killed all fishes. The area was observed monthly for the following year, to study the recovery of fish populations. The study also included observations on growth rate of fish and size of populations. Recovery of fish populations was complete 10 to 12 months after the poisoning. It is believed that this is due to the relatively small size of the contaminated area and the survival of most invertebrates that constitute an important part of the biotope of the fish.

Temperature effects on behavior and survival of marine invertebrates exposed to variations in hydrostatic pressure

Investigation into the pressure resistance of 8 intertidal species belonging to the genera, Uca, Sesurma, Talorchestia and Littorina from the Northern Gulf of Mexico and Panama sheds light on the relationships between temperature and hydrostatic-pressure resistance. Generally, increasing temperature increases the pressure required to elicit reversible reactions such as “increased activity” and tetany, or paralysis, wheroas increasing temperature generally evokes the irreversible response of death (LD50) at a decreasing pressure. Tropical stenotherms tend to be more sensitive to hydrostatic pressure than eurythermal-temperate species at the same or similar temperatures.