Reciprocal Relationships Between Exotic Rusty Crayfish,Macrophytes, and <Emphasis Type="Italic">Lepomis</Emphasis> Species in Northern Wisconsin Lakes

Abstract The non-native rusty crayfish (Orconectes rusticus) has invaded many lakes of northern Wisconsin, profoundly changing littoral zones in the process. There are other lakes that have been invaded, but do not exhibit these changes. We hypothesized that endogenous feedbacks could form involving rusty crayfish, the macrophytes they destroy, and Lepomis species whose abundance is positively related to macrophyte abundance and also consume juvenile crayfish. We assessed this proposal with long-term data from one lake, a regional comparative study, and a case study of Lepomis predation on crayfish. Through time and across lakes, abundances of rusty crayfish, littoral macrophytes and species of the genus Lepomis were related in a fashion that indicated a set of feedbacks that regulate the abundance of all three. Intense predation on juvenile crayfish by abundant Lepomis is capable of maintaining some crayfish populations at low abundance. Thus, some lakes display profound ecological changes where crayfish achieve high abundance, and others sustain crayfish at low abundance. Consequently, lakes invaded by rusty crayfish may take on the appearance of alternative ecological regimes. Direct experimentation is necessary to determine if, and under what conditions, a lake can exist in either regime. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The shell of <Emphasis Type="Italic">Hexaplex (Trunculariopsis) trunculus</Emphasis> (Gastropoda: Muricidae) as a mobile hard substratum for epibiotic polychaetes (Annelida: Polychaeta) in the Ria Formosa (Algarve coast—southern Portugal)

This work reports and illustrates secondary colonisation of Hexaplex (Trunculariopsis) trunculus shells by polychaetes in the Ria Formosa lagoon (Algarve coast—southern Portugal). Information is presented in terms of qualitative and quantitative data on epibiotic polychaetes, fouling frequency, degree of epibiosis, preferential areas for colonisation and incidence of shell damages. A total of 2,880 polychaetes belonging to 10 families were identified. Besides Spirorbidae (not quantified), the most abundant families were Serpulidae (67.5%), Sabellidae (10.2%), Sabellariidae (9.6%) and Cirratulidae (8.5%). From a total of 2,264 T. trunculus individuals analysed for epibiosis, 28.4% were non-fouled, 66.8% were intermediately fouled and 4.8% were heavily fouled. The fouling frequency, degree of epibiosis and incidence of damages in the shell spire increased markedly with T. trunculus shell length. Some epibiotic polychaetes were located preferentially on/or nearby particular features of T. trunculus shells, which probably facilitate settlement and tube construction, in addition to provide some protection against tube damage. The main consequences of epibiosis (benefits and disadvantages) for the gastropod basibiont (T. trunculus) are discussed. The present study apparently indicates that besides burrowing into soft bottom substrates, sporadic inter-tidal exposure and mutual predation on epibiosis, T. trunculus lacks other typical antifouling defence adaptations. Handling editor: K. Martens     

Inhibitory Effects of Mediterranean Sponge Extracts and Metabolites on Larval Settlement of the Barnacle Balanus amphitrite

One of the most promising alternative technologies to antifouling paints based on heavy metals is the development of coatings whose active ingredients are compounds naturally occurring in marine organisms. This approach is based on the problem of epibiosis faced by all marine organisms and the fact that a great number of them cope with it successfully. The present study investigated the antifouling activity of a series of extracts and secondary metabolites from the epibiont-free Mediterranean sponges Ircinia oros, I. spinosula, Cacospongia scalaris, Dysidea sp., and Hippospongia communis. Antifouling efficacy was evaluated by the settlement inhibition of laboratory-reared Balanus amphitrite Darwin cyprids. The most promising activity was exhibited by the metabolites 2-[24-acetoxy]-octaprenyl-1-4-hydroquinone (8a), dihydrofurospongin II (10), and the alcoholic extract of Dysidea sp.     

Effects of environmental stress on intertidal mussels and their sea star predators

Consumer stress models of ecological theory predict that predators are more susceptible to stress than their prey. Intertidal mussels, Mytilus californianus, span a vertical stress gradient from the low zone (lower stress) to the high zone (higher thermal and desiccation stress), while their sea star predators, Pisaster ochraceus, range from the low zone only into the lower edge of the mussel zone. In summer 2003, we tested the responses of sea stars and mussels to environmental stress in an experiment conducted on the Oregon coast. Mussels were transplanted from the middle of the mussel bed to cages in the low and high edges of the mussel bed. Sea star predators were added to half of the mussel cages. Mussels and sea stars were sampled between June and August for indicators of sublethal stress. Mussel growth was measured, and tissues were collected for heat shock protein (Hsp70) analyses and histological analyses of reproduction. Sea stars were weighed, and tissues were sampled for Hsp70 analyses. Mussels in high-edge cages had higher levels of total Hsp70 and exhibited spawning activity earlier in the summer than mussels in the low-edge cages. Sea stars suffered high mortality in the high edge, and low-edge sea stars lost weight but showed no differences in Hsp70 production. These results suggest that stress in the intertidal zone affected the mobile predator more than its sessile prey, which is consistent with predictions of consumer stress models. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The new threat to Italian inland waters from the alien crayfish “gang”: the Australian Cherax destructor Clark, 1936

Biological invasions inflict damage to the ecology, economy, and human health, and pose serious threats to the native communities. Among the many invasive taxa, crayfish have attracted much attention by scientists and policy makers. Recently, an established population of an alien species of crayfish, new for Italy, was found in the Natural Preserve of “Laghi di Ninfa” (central Italy). Based on morphological and genetic evidence (molecular barcoding of COI and 16S rDNA), we classified it at subspecies level as the Parastacidae Cherax destructor destructor, native to Australia. Its introduction possibly occurred at the end of the 1980s but the species seems to be still confined in the preserve. The low temperature of the adjacent waters may be a barrier against its natural spreading but not against its intentional translocation into natural waters by man. Because of the invasive history of C. destructor, eradication of this population is urgent and still economically profitable. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: Pierluigi Viaroli     

The site of settlement indicates commensalism between bluemussel and its epibiont

Summary The site of settlement of barnacles (Balanus improvisus) attached on shells of bluemussels (Mytilus edulis) was mapped from a sample of mussels collected in the Baltic Sea. Most barnacles had settled near the siphonal apertures of the mussel. An experiment was made to measure the disadvantages and advantages that living in close association brings to barnacles and mussels. The barnacles on shells of living mussels were shown to grow significantly faster than those on empty mussel shells. Presence of barnacles had no effects on growth of mussels. The two-species association under study was demonstrated to be a case of commensalism.     

Behavioral Responses of a Small Native Fish to Multiple Introduced Predators

Rainbow trout, Oncorhynchus mykiss, and crayfish, Orconectes virilis, have been introduced for the last century into North American streams inhabited by native fishes. We sought to determine the behavioral response of a federally threatened cyprinid, Little Colorado spinedace, Lepidomeda vittata, in the concurrent presence of multiple nonnative predators (rainbow trout and crayfish), as well as the response to the presence of a combination of native (Apache trout, Oncorhynchus apache) and nonnative (crayfish) predators. We held spinedace in artificial streams and exposed them to four treatments: (1) control, (2) crayfish added, (3) trout added, and (4) both crayfish and trout added. Only a single spinedace was consumed over the course of the experiments; it was captured and preyed upon by a crayfish. When both crayfish and Apache trout were present, spinedace response was similar to what it was when only Apache trout were present (decreased movement in and out of refuge), suggesting that crayfish and Apache trout did not mutually influence spinedace behavior. However, when both rainbow trout and crayfish were present, spinedace not only decreased movements in and out of refuge, but also decreased activity rates. We suggest that crayfish and rainbow trout mutually influence spinedace behavior and recommend control or elimination of crayfish and rainbow trout from spinedace critical habitat or potential reintroduction sites. In addition, potential reintroduction sites for Apache trout should be evaluated based on presence of crayfish and spinedace to avoid potential multiple predator interactions and negative effects on spinedace.     

First record of an epibiosis between the sand crab Emerita analoga (Stimpson, 1857) (Decapoda: Hippidae) and the mussel Semimytilus algosus (Gould, 1850) (Bivalvia, Mytilidae) in southern Peru

Coastal zones of the Humboldt Current Upwelling System (HCUS) are composed both of rocky and sandy beaches inhabited by macrozoobenthic communities. These show oscillating changes in the dominance of species; the abundance of the sand crab Emerita analoga is linked to phases of the El Niño Southern Oscillation (ENSO). The biogenic surfaces of these crabs serve as substrate for opportunistic colonizers. This study is the first record of an epibiosis between E. analoga and the rock mussel Semimytilus algosus, detected at a southern Peruvian sandy beach. Mussels fouled a wide size-range of adult E. analoga (7.3%) but they themselves belonged to small-size classes. The largest S. algosus was 17.4 mm in length. Highest permanence of epibionts was found on larger sand crabs (maximum between 24 and 27 mm). Significantly more mussels were found on the ventral surface (39.4%) compared to 10 other surface areas of the sand crab. Possible benefits and disadvantages of the observed epibiosis for both the basibiont and the epibiont are discussed.     

New records and distributions of two North American branchiobdellidan species (Annelida: Clitellata) from introduced signal crayfish, <Emphasis Type="Italic">Pacifastacus leniusculus,</Emphasis> in Japan

This is the first report of two North American branchiobdellidans, Sathodrilus attenuatus Holt, 1981, and Xironogiton victoriensis Gelder and Hall, 1990, on the signal crayfish, Pacifastacus leniusculus (Dana, 1852) introduced into Japan from the Columbia River system, northwestern North America. Signal crayfish from 12 localities in eastern and northern Hokkaido, Japan, were examined and each supported S. attenuatus. In addition, an individual of this species was found on preserved material from Ishikawa Prefecture, central Honshu. All of these branchiobdellidans reported in Hokkaido most probably came from the original population of signal crayfish introduced into Lake Mashu, Hokkaido, Japan, in 1930. It is suggested that the use of non-pathogenic branchiobdellidans, when present, provides an easy method for tracing the spread of crayfishes around Japan and could also be applied in other countries and continents. Specimens of X. victoriensis were only found on crayfish in a stream at Akashina in Nagano Prefecture, central Honshu, Japan. Although the signal crayfish appears to be displacing the endemic Japanese crayfish, C. japonicus, no native branchiobdellidans were found on any of the introduced signal crayfish examined.     

Reduction of cyanobacterial toxins through coprophagy in Mytilus edulis

An experiment was conducted to follow the fate of the cyanobacterial toxin, nodularin, produced by Nodularia spumigena through ingestion by Mytilus edulis and re-ingestion of faecal material (coprophagy). Mussels were fed with cultures of N. spumigena, and the faeces that were produced were fed to other mussels not previously exposed to N. spumigena. Concentrations of nodularin were measured in the food (N. spumigena), the mussels and in the faeces in order to make a toxin budget. High concentrations of nodularin were found in the mussels and their faeces after 48 h incubation with N. spumigena. When the toxic faeces were fed to new mussels, the toxin content of faeces was reduced from 95 μg nod g⁻¹ dry weight (DW) to 1 μg nod g⁻¹ DW through the process of coprophagy. Hence, when toxic faeces were fed to mussels, the nodularin concentration of the resulting faecal material was reduced by 99%. Pseudofaeces were produced when the mussels were grazing on N. spumigena, but not when grazing on faeces. The pseudofaeces contained high concentrations of nodularin and apparently intact N. spumigena cells. However, these cells were growth-inhibited and their potential contribution to seeding a bloom is probably limited. Our data indicate that a large fraction of ingested nodularin in M. edulis is egested with the faeces, and that the concentration of nodularin in the faeces is reduced when faeces are re-ingested.     

The role of omnivorous crayfish in littoral communities

Large omnivorous predators may play particularly important roles determining the structure of communities because of their broad diets and simultaneous effects on multiple trophic levels. From June 2001 to June 2002 we quantified community structure and ecosystem attributes of six newly establishing freshwater ponds (660 m² each) after populations of omnivorous crayfish (Orconectes virilis) were introduced to three of the ponds. Crayfish preyed heavily on fish eggs in this experiment, which reduced recruitment of young-of-year fish. This effect indirectly enhanced zooplankton biomass in crayfish ponds. Phytoplankton abundance exhibited a more complex pattern and was probably influenced by non-trophic (e.g., bioturbation) effects of crayfish. Peak dissolved oxygen levels were lower in the crayfish ponds indicating that they had lower primary production: respiration ratios. Metaphytic algae were strongly affected by crayfish presence; filamentous greens quickly disappeared and the blue-green Gleotrichia (a less preferred food item) eventually dominated the composition in crayfish ponds. Chara vulgaris and vascular macrophytes established 34% cover in control ponds by June 2002, but were not able to establish in crayfish ponds. Two important periphyton herbivores (tadpoles and gastropods) were absent or significantly reduced in the crayfish ponds, but periphyton differences were temporally variable and not easily explained by a simple trophic cascade (i.e., crayfish—snails and tadpoles—periphyton). Our results indicate that crayfish can have dramatic direct and indirect impacts on littoral pond communities via feeding links with multiple trophic levels (i.e., fish, invertebrates, and plants) and non-trophic activities (bioturbation). Although the effects of omnivorous crayfish on littoral communities can be large, their complex effects do not fit neatly into current theories about trophic interactions or freshwater community structure.     

Multiplex specific PCR for identification of the genera Actinopolyspora and Streptomonospora, two groups of strictly halophilic filamentous actinomycetes

The genera Actinopolyspora and Streptomonospora are two groups of extremely halophilic filamentous actinomycetes. Members of these two genera are isolated frequently, probably due to the high occurrence of these actinomycetes in the hypersaline soil environment. Although members of these genera can be identified by micromorphological criteria, the extensive chemotaxonomic characterization of each new isolates is a time-consuming task which cannot always be undertaken when handling large numbers of isolates as is the case in natural products screening programmes. In this work, the design of one set of genus-specific PCR primers which allows rapid detection of members of the genus Actinopolyspora by means of PCR amplification is presented. And we developed a multiplex PCR protocol for identification of the species of the genera Actinopolyspora and Streptomonospora, simultaneously. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The relationship between water velocity,energetic costs,and microhabitat use in four North American stream fishes

Freshwater crayfish are key members of aquatic communities due to their large size and abundance. Although most commonly regarded as herbivores and detritivores, they are also selective predators. The crayfish plague fungus Aphanomyces astaci (Schikora) led to the elimination of a stock of white-clawed crayfish, Austropotamobius pallipes (Lereboullet) from Lough Lene, Co. Westmeath, in 1987. Samples taken of the flora and benthic communities of two Irish lakes, one (Lough Bane) formerly containing crayfish and the other (Lough Lene) immediately following a plague outbreak, were compared to similar samples taken a year later and ecological shifts were noted and compared to laboratory feeding results. Over time, Chara strands increased in mean length, and molluscs became more abundant.     

The genera <Emphasis Type="Italic">Bispira</Emphasis> Krøyer, 1856 and <Emphasis Type="Italic">Stylomma</Emphasis> Knight-Jones, 1997 (Polychaeta,Sabellidae): systematic revision,relationships with close related taxa and new species from Australia

A cladistic analysis undertaken to test monophyly of Bispira and Stylomma (including new species of both genera) and to ascertain relationships with related taxa reveals that Bispira is paraphyletic without the inclusion of Pseudobranchiomma and Branchiomma, and that Stylomma is monophyletic due to the presence of a structure on the dorsal basal flanges which has never been described before. New species of Bispira and Stylomma from Australia are described. Bispira serrata n. sp., differs from the other species of the genus in having serrated radiolar flanges whereas all other Bispira species have smooth flanges or lack them, and also by the shape of the thoracic and abdominal uncini, which are short-handled and have 2–3 rows of big teeth above the main fang, instead of having medium-sized handles and small, numerous rows of teeth over the main fang. Stylomma juani n. sp., is characterized by the presence of serrated radiolar flanges and unpaired compound eyes along the branchial radioles, whereas other species in the genus have smooth radiolar flanges and subterminal compound radiolar eyes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: K. Martens     

Commensals of Mytilus galloprovincialis in the Black Sea: Urastoma cyprinae (Turbellaria) and Polydora ciliata (Polychaeta)

The intensity of infection of the mussel Mytilus galloprovincialis Lamarck in the Black Sea by the turbellarian Urastoma cyprinae (Graff), which lives on its gills, was found to be higher in larger hosts, reaching a maximum in mussels of 50–70 mm length. Greater numbers occured in mussels inhabiting a silty bottom than in cultivated mussels suspended above the bottom. Over the period 1982–1987, U. cyprinae was most numerous in winter and especially so in years that were colder. The spionid polychaete Polydora ciliata (Johnston) also infects M. galloprovincialis, burrowing into the shell. Young spionids of up to 1 mm length occured in mussels with a shell length of 35 mm. Numbers of this commensal reached a maximum in mussels of intermediate size.     

Assessment of Potential Impacts of Exotic Species on Populations of a Threatened Species, White Sands Pupfish, Cyprinodon tularosa

The potential impact of introduced species on rare taxa is of particular concern to conservation biologists. We evaluate the impacts of western mosquitofish (Gambusia affinis) and virile crayfish (Orconectes virilis) on experimental populations of a threatened species, the White Sands pupfish (Cyprinodon tularosa). Forty experimental pupfish populations were exposed to one of four treatments; (a) 1 crayfish, (b) 4 crayfish, (c) 5 adult mosquitofish and (d) control. Pupfish population size and biomass was monitored over the duration of one breeding season. A repeated measure multiple analysis of covariance revealed a significant effect of treatments on response variables (population size and biomass) (P<0.0001). Mosquitofish had a significant effect on population size and biomass (P=0.0330). The effect of one crayfish was not significant (P=0. 0683). However, 4 crayfish had a significant effect (P<0.0001) on population size. We use these data, along with information on environmental tolerances of crayfish and mosquitofish, to evaluate risks for specific pupfish populations. An erratum to this article is available at .     

Regulation of expression of Na<Superscript>+</Superscript>-translocating NADH:quinone oxidoreductase genes in <Emphasis Type="Italic">Vibrio harveyi</Emphasis> and <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis>

The expression of genes encoding sodium-translocating NADH:quinone oxidoreductase (Na⁺-NQR) was studied in the marine bacterium Vibrio harveyi and in the enterobacterium Klebsiella pneumoniae. It has been shown that such parameters as NaCl concentration, pH value, and presence of an uncoupler in the growth media do not influence significantly the level of nqr expression. However, nqr expression depends on the growth substrates used by these bacteria. Na⁺-NQR is highly repressed in V. harveyi during anaerobic growth, and nqr expression is modulated by electron acceptors and values of their redox potentials. The latter effect was shown to be independent of the ArcAB regulatory system. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Accession number: EF394942 (Vibrio harveyi arcB gene, partial cds).     

Variation in scope for growth: a test of food limitation among intertidal mussels

Wellington Harbour supports large populations of the mussels Aulacomya maoriana, Mytilus galloprovincialis and Perna canaliculus that are almost entirely absent from nearby coastal locations in Cook Strait. We calculated scope for growth (SFG) using ambient Cook Strait water over a broad temporal scale and a broad range of seston conditions to determine if negative SFG explains this phenomenon. Although all three mussel species had positive mean SFG values, variation in SFG was high and negative values often occurred: A. maoriana 19.1 J g⁻¹ h⁻¹, 43% of mussels showed negative SFG; M. galloprovincialis 1.26, 52% negative SFG; P. canaliculus 45.6, 27% negative SFG. Negative SFG was most often due to negative absorption efficiency caused by metabolic faecal loss that is characteristic of mussels feeding in environments with low seston quality. From our ecophysiology data we constructed a model to estimate SFG based on physiological responses to the narrow range of seston conditions typical of Cook Strait (Model One), and a model to estimate SFG based on physiological responses of mussels to the broad range of seston conditions typical of Wellington Harbour and Cook Strait (Model Two). We used seston data collected over an 18-month period from sites in Wellington Harbour and Cook Strait to derive 159 estimates of species-specific mussel SFG from both models. Both models produced higher estimates of SFG for mussels in the Harbour compared with those at Cook Strait sites. This was consistent with elevated particulate concentrations in the Harbour than at Cook Strait sites, and in agreement with previous studies. For Cook Strait mussels, both models produced negative estimates of net energy balance for long periods of time (several months), whereas for Harbour mussels negative SFG estimates were generally short in duration. We conclude that our short-term laboratory-based determinations of SFG and our long-term bioenergetics modelling estimates do not conclusively support the hypothesis of food limitation for three coexisting taxa of mussels in the intertidal region of Cook Strait, New Zealand. Handling editor: P. Viaroli     

A unique highly thermostable 2-phosphoglycerate forming glycerate kinase from the hyperthermophilic archaeon <Emphasis Type="Italic">Pyrococcus horikoshii</Emphasis>: gene cloning,expression and characterization

A glycerate kinase (GK) gene (PH0495) from the hyperthermophilic archaeon Pyrococcus horikoshii, was cloned and expressed in Escherichia coli. The recombinant protein was purified to homogeneity by affinity chromatography and ion exchange chromatography. The enzyme was likely a homodimer based on SDS-PAGE (47 kDa) and gel filtration chromatography (100 kDa) analysis. A radioisotope-labeling examination method was initially used for the enzymatic activity detection, and the enzyme (GK_ph) was found to catalyze the formation of 2-phosphoglycerate using d-glycerate as the substrate. The enzyme exhibited unique phosphoryl donor specificity with maximal activity towards pyrophosphate. The temperature and pH optima of the enzyme were 45°C and 7.0, respectively, and about half of the maximal activity remained at 100°C. The enzyme was highly thermostable with almost no loss of activity at 90°C for 12 h. Based on sequence alignment and structural comparison it was assigned to group I of the trichotomy of GKs. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.