Invertebrates

The suspension-feeding metazoan subkingdom Lophophorata exhibits characteristics of both deuterostomes and protostomes. Because the morphology and embryology of lophophorates are phylogenetically ambiguous, their origin is a major unsolved problem of metazoan phylogenetics. The complete 18S ribosomal DNA sequences of all three lophophorate phyla were obtained and analyzed to clarify the phylogenetic relationships of this subkingdom. Sequence analyses show that lophophorates are protostomes closely related to mollusks and annelids. This conclusion deviates from the commonly held view of deuterostome affinity.

In recent years, a variety of approaches to deriving sediment quality guidelines have been developed. One approach relies on establishing an empirical relationship between the concentration of a contaminant in sediment and the condition of some biological indicator, for example, combining measured sediment concentrations of contaminants combined with data on colocated benthic species to measure in situ community effects of contamination. Biological threshold concentrations derived in this manner are being considered or have already been adopted by some regulatory agencies as a means for deriving sediment guidelines (e.g., Canada's Provincial Sediment Quality Guidelines). In order to test the validity of this method, we constructed several Monte Carlo simulations to illustrate that the methodology used to develop these guidelines is flawed by the effects of sampling and statistical artifacts that emerge from undersampling a lognormal density function. As a case study, this paper will present the screening level concentration method used by the Ontario Ministry of the Environment (Toronto, ON, Canada) and provide the results of several probabilistic exercises highlighting these issues. We present a word of caution on the applicability of methods that rely exclusively on statistical and mathematical relationships between invertebrate data and sediment concentrations to derive sediment quality guidelines.

The solitary ascidian Phallusia nigra is rarely fouled by epibionts. Here, we tested the antifouling activity of its crude extracts in laboratory and field assays. P. nigra extracts inhibited the growth of all eight tested environmental bacteria and two of four laboratory bacteria. Extracts of the sympatric, but fouled solitary ascidian Herdmania momus inhibited only one test bacterium. Scanning electron microscopy confirmed that the tunic surface of P. nigra is largely bacteria-free. Both ascidian extracts significantly inhibited the larval metamorphosis of the bryozoan Bugula neritina at the tested concentration range of 0.05-2 mg ml(-1). Both crude extracts were toxic to larvae of the brine shrimp Artemia salina at natural volumetric whole-tissue concentrations, but only P. nigra showed activity at 2 mg ml(-1) and below (LC50 = 1.11 mg ml(-1)). P. nigra crude extracts also significantly reduced the settlement of barnacles, polychaetes, and algae in Mediterranean field assays and ...

BACKGROUND, AIMS AND SCOPE Lakes developing in volcano craters can become highly acidic through the influx of volcanic gases, yielding one of the chemically most extreme natural environments on earth. The Kawah Ijen crater lake in East Java (Indonesia) has a pH < 0.3. It is the source of the extremely acidic and metal-polluted river Banyupahit (45 km). The lake has a significant impact on the river ecosystem as well as on a densely populated area downstream, where agricultural fields are irrigated with water with a pH between 2.5 and 3.5. The chemistry of the river water seemed to have changed over the past decade and the negative effect in the irrigation area increased. A multidisciplinary approach was used to investigate the altered situation and to get insight in the water chemistry and the hydrological processes influencing these alterations. Moreover, a first investigation of the effects of the low pH on ecosystem health and human health was performed. METHODS Water samples ...

Biological and environmental contrasts between aquatic and terrestrial systems have hindered analyses of community and ecosystem structure across Earth's diverse habitats. Ecological stoichiometry provides an integrative approach for such analyses, as all organisms are composed of the same major elements (C, N, P) whose balance affects production, nutrient cycling, and food-web dynamics. Here we show both similarities and differences in the C:N:P ratios of primary producers (autotrophs) and invertebrate primary consumers (herbivores) across habitats. Terrestrial food webs are built on an extremely nutrient-poor autotroph base with C:P and C:N ratios higher than in lake particulate matter, although the N:P ratios are nearly identical. Terrestrial herbivores (insects) and their freshwater counterparts (zooplankton) are nutrient-rich and indistinguishable in C:N:P stoichiometry. In both lakes and terrestrial systems, herbivores should have low growth efficiencies (10-30%) when cons...

Although several ecological indices have been developed worldwide to assess the ecological quality (EcoQ) status of coastal environments, their applicability remains in question. The present study evaluated the performance of 14 univariate and multivariate indices selected to provide a good description of benthic EcoQ status. We specifically investigated on i) spatial and regional variability, ii) (dis)similarity between ecological indices, and iii) the association of selected indices against heavy metal pollution. Benthic community data were collected from six coastal regions of Korea (n=365) that have varying land-use activity in adjacent inland areas (municipal, industrial, and rural). Abiotic sedimentary parameters were also considered as possible pressures associated with benthic community responses, including grain size, organic carbon content, and heavy metal pollution. The macrozoobenthic biodiversity and EcoQ results generally well reflected the geographical settings and th...

Marine organisms provide some of the most important examples of phenotypic plasticity to date. We conducted a systematic review to cast a wide net through the literature to examine general patterns among marine taxa and to identify gaps in our knowledge. Unlike terrestrial systems, most studies of plasticity are on animals and fewer on plants and algae. For invertebrates, twice as many studies are on mobile than sessile species and for both animals and plants most species are benthic intertidal zone taxa. For invertebrates, morphological plasticity is most common, while chemical plasticity is most common among algae. For algae, as expected, predators (inducible defences) are the primary cue for triggering plasticity. Surprisingly, for invertebrates the abiotic environment is the most common trigger for plasticity. Inducible defences in invertebrates have received great attention and predominate for a few well-studied species, which can bias perceptions; but, their predominance overall is not supported by the full data set. We also identified important research needs, including the need for data on non-temperate zone taxa, planned experiments to directly test the role of habitat variability and the prevalence of plasticity. We also need information on the lag time for induction of plastic traits, which is critical for determining the adaptive value of phenotypic plasticity. Studies of early life stages and studies that link plasticity to mechanisms that produce phenotypes are critically needed, as are phylogenetic comparative studies that can be used to examine responses of organisms to both short- and long-term change.

Neonicotinoids, broad-spectrum systemic insecticides, are the fastest growing class of insecticides worldwide and are now registered for use on hundreds of field crops in over 120 different countries. The environmental profile of this class of pesticides indicate that they are persistent, have high leaching and runoff potential, and are highly toxic to a wide range of invertebrates. Therefore, neonicotinoids represent a significant risk to surface waters and the diverse aquatic and terrestrial fauna that these ecosystems support. This review synthesizes the current state of knowledge on the reported concentrations of neonicotinoids in surface waters from 29 studies in 9 countries world-wide in tandem with published data on their acute and chronic toxicity to 49 species of aquatic insects and crustaceans spanning 12 invertebrate orders. Strong evidence exists that water-borne neonicotinoid exposures are frequent, long-term and at levels (geometric means=0.13μg/L (averages) and 0.63μg...

Eucaridan evolution involved a process starting from a body organization characterized by an elongate and cylindrical cephalothorax, a well-developed abdomen composed of swimming appendages, ending in a tail fan formed by flattened uropods and a telson. This process would lead, ultimately, to a body organization characterized by a shortened and depressed cephalothorax, and a reduced and ventrally folded abdomen. This ultimate process is typically known as carcinization, and is commonly defined as the process of becoming a crab. In this work, the evolution of the superorder Eucarida was studied using complex networks. A new definition of crab and carcinization are given based on the results obtained. A crab is a topological structural closure that determines the formation of a triadic central core. The evolution of the crab implied the formation of a triadic structure with high closeness centrality, formed by the cephalon, the fused thoracomere 1-4 and the carapace, which represented a highly stable hierarchical core deeply buried or enclosed in the topological structure of the network, responsible for the generation of a highly integrated and robust topology. Under this new definition, the representative of the infraorder Anomura used in this work, which is commonly considered as a crab, is not. This network seemed to be characterized by the presence of a quasi-dyadic structure, formed by the cephalon and the carapace, which was not sufficient for generating the topological closure.