Dan Rittschof

Settlement and behavior in relation to flow and surface in larval barnacles, Balanus amphitrite Darwin

Abstract Behavior and settlement of laboratory-reared larval barnacles were examined with respect to age of larvae, type of surface (polystyrene and glass), and treatment of surface with settlement factor. Young cyprids were more discriminating in settlement than old cyprids. Young cyprids settled more on glass than on polystyrene. Young cyprids settled in higher percent on either polystyrene or glass in the presence of settlement factor. Settlement factor had no detectable effect on settlement of older cyprids. A rapid (2 to 10 min) quantitative assay for study of larval barnacle responses to surfaces was developed. The assay can be used to investigate molecular modifiers of larval barnacle behavior. Surfaces treated by adsorption of settlement factor from a 2.5 μ/ml solution promoted reversible attachment by cyprids. Cyprids separated on the basis of their behavior were tested in settlement assays. In the absence of settlement factor, there were marked differences in percent settlement between classes. Addition of settlement factor to settlement assays did not affect settlement of certain behavior classes and increased settlement over six-fold in others.

Inhibition of attachment of larval barnacles, Balanus amphitrite, by bacterial surface films

Films of bacteria on solid substrata can positively or negatively influence the attachment of marine invertebrate larvae. Effects of marine bacteria on the attachment of cypris larvae of the barnacle Balanus amphitrite Darwin were examined in the laboratory. Bacteria, grown to mid-exponential phase and allowed to adsorb irreversibly to polystyrene petri dishes, attached in densities of 107 cells cm-2. Assays (22h) were used to compare the effects of adsorbed cells of 18 different bacterial species on larval barnacle attachment. Most of the adsorbed bacteria either inhibited or had no effect on larval attachment compared to clean surfaces. Experiments testing the effect of larval age on barnacle attachment were conducted with six species of bacteria and showed that older larvae attached in higher percentages to clean surfaces and that bacterial films generally inhibited larval attaschment. Both the species of bacteria and the in situ age of the adsorbed bacteria affected barnacle attachment response: older films of Deleya (Pseudomonas) marina were more inhibitory. Bacterial extracellular materials may be involved in the inhibitory process.

Barnacle in vitro assays for biologically active substances: Toxicity and Settlement inhibition assays using mass cultured Balanus amphitrite amphitrite darwin

The development of non‐toxic or non‐polluting antifouling additives that can be formulated in practical coatings requires assays involving target organisms. Assays that test both for the effective and toxic concentrations of active compounds are useful. It is also desirable if the assay can provide information regarding the performance that can be expected if the compounds are incorporated into different matrices. Described here are the simple laboratory assays that have been developed using the barnacle, Balanus amphitrite, a common fouling organism found throughout temperate and tropical seas. One of the assays depends on synchronous year‐round mass culture, the procedure for which is described, of cypris larvae. The laboratory assays provide quantitative estimates of toxicity and settlement inhibition of barnacles. The methods described provide an excellent system for the use of barnacles to study the interaction of the test compounds and surfaces.

Influence of delayed metamorphosis on survival and growth of juvenile barnacles Balanus amphitrite

Competent cyprid larvae of the barnacle Balanus amphitrite Darwin were prevented from metamorphosing in the laboratory for 3 or 5 d using three different techniques (holding at low temperature, crowding, and detaining on a silanized surface). We then assessed the effects of prolonging larval life on post-metamorphic growth and survival, in comparison with control individuals that metamorphosed soon after they were competent to do so. Seven experiments were conducted over 2 yr (July 1987 to September 1989). In all experiments (each with six replicates per treatment), postponing larval metamorphosis for 3 or 5 d dramatically depressed postmetamorphic growth rate (P<0.05), although metamorphic success and post-metamorphic survival were not affected (P>0.10). The results suggest that B. amphitrite cyprids deferring their metamorphosis in the field may be less successful in competing for space, at least during the first few weeks of postlarval life.

Factors influencing initial larval settlement: temporal, spatial and surface molecular components

The impact of initial surface chemistry on settlement of barnacle, bryozoan, and hydroid larvae was assessed. Temporal (on a scale of weeks to months) and fine scale spatial (centimeter to meter) variation in settlement were quantified. Four arrays of silanized glass surfaces, deployed at ≈2-wk intervals, were monitored after 1 and 3 days of immersion. Settlement of all larval types exhibited strong temporal variation. There was a 25, 22- and 18-fold difference between the highest and lowest Day 1 settlement for barnacles, bryozoans and hydroids, respectively. Bryozoan and hydroid settlement was spatially variable, barnacle settlement was not. Barnacle and bryozoan settlement was influenced by inttial surface chemistry, hydroid settlement was not. For barnacles, there was a 2-fold difference between total settlement over the four arrays on untreated glass and diphenyl-silanized surfaces; for bryozoans, there was a 51-fold difference, and in the opposite direction. There was a negative correlation between barnacle and bryozoan settlement with respect to surface. This result was independent of the presence of the other species. Bryozoan settlement was also spatially and temporally quantified in a separate, single surface 56-h array, and total bryozoan settlement ·h−1 was found to be correlated with light intensity. Patterns of initial colonization were strongly influenced by surface chemistry and spatial temporal variation in larval supply. These effects on initial colonization may influence subsequent community development.

Molecular approaches to nontoxic antifouling

Summary A consequence of environmental and human health concerns arising from the use of toxic metals in marine antifouling coatings has been to recognise the need for a nontoxic alternative to fouling control. Recent research has focused on two approaches to this problem: the development of (a) foul-release coatings that work on the principle of either low surface free energy or coating ablation, and (b) coatings that incorporate a compound(s) that is nontoxic, or at least environmentally benign, that will deter fouling. Here we discuss the nature of the fouling problem and a new technology that is emerging to address it. The use of natural marine products and of analogues to these compounds holds considerable promise and is an area of intense research. It is recognized, however, that a melding of the technologies of foul-release and foul-deterrence may be required to develop broad spectrum, nontoxic antifouling coatings. This approach may more closely reflect antifouling strategies adopted by marine org...

Biomimetic Anchors for Antifouling and Antibacterial Polymer Brushes on Stainless Steel

Barnacle cement (BC) was beneficially applied on stainless steel (SS) to serve as the initiator anchor for surface-initiated polymerization. The amine and hydroxyl moieties of barnacle cement reacted with 2-bromoisobutyryl bromide to provide the alkyl halide initiator for the surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA). The hydroxyl groups of HEMA polymer (PHEMA) were then converted to carboxyl groups for coupling of chitosan (CS) to impart the SS surface with both antifouling and antibacterial properties. The surface-functionalized SS reduced bovine serum albumin adsorption, bacterial adhesion, and exhibited antibacterial efficacy against Escherichia coli (E. coli). The effectiveness of barnacle cement as an initiator anchor was compared to that of dopamine, a marine mussel inspired biomimetic anchor previously used in surface-initiated polymerization. The results indicate that the barnacle cement is a stable and effective anchor for functional surface coatings and polymer brushes.

EFFECTS OF INTERSPECIFIC COMPETITION ON FITNESS OF THE HERMIT CRAB CLIBANARIUS TRICOLOR

Clibanarius tricolor overlaps strongly in shell utilization with the other common species of intertidal hermit crabs found in the Florida Keys. Laboratory observations indicated C. tricolor can dominate Clibanarius antillenisis in shell fights, while Calcinus tibicen dominates C. tricolor. In micro-areas of sympatry with C. antillensis, C. tricolors shell fit is better and egg production parameters not affected when compared to adjacent areas where only C. tricolor occurs. Sympatry with Calcinus tibicen results in a poorer shell fit, a smaller shell size for a given size crab, a smaller mean size of crab, and a disruption of the relationship between clutch size and crab size:shell weight ratio. A strong effect of shell species on the probability of Y Y being ovigerous was noted. It is suggested that the ecological separation which characterizes these species over most of their ranges was an evolutionary response, in part, to the effects of interspecific shell competition.

Chemical attraction of hermit crabs and other attendants to simulated gastropod predation sites

Simulated gastropod predation sites were observed in the gulf intertidal near the Edward Ball Marine Laboratory, Sopchoppy, Florida,Fundulus similis, Callinectes sapidus, Melongena corona, Clibanarius vittatus, andPagurus longicarpus were attracted to the sites by small molecules released passively from the flesh of wounded or dead animals. Flesh consumers (F. similis, C. sapidus, andM. corona) were attracted to molecules released from the flesh of bivalves, gastropods, and crabs. Shell users (C. vittatus andP. longicarpus) were attracted only to small molecules from gastropod flesh, withP. longicarpus attendingP. duplicatas sites whileC. vittatus preferentially attendedM. corona, Busycon contrarium, andBusycon spiratum sites. Flesh consumers and shell users may be attracted to the sites by different sets of small molecules. The addition of proteolytic enzymes to the flesh increased the attendants at a site, indicating that the attractant molecules might be amino acids or small peptides. Flesh consumers were attracted to the sites primarily in the first 12 hr while the shell users were attracted from 2 hr to several days postinitiation. New shells were attractive to hermit crabs up to 12 hr after entry by a hermit crab. The shell species of the attendantC. vittatus were in different proportions than the generalC. vittatus population, and the shell fit of theP. longicarpus attendants was not as good as the general population ofP. longicarpus. Significantly moreC. vittatus attended than P. longicarpus, and it was speculated that there were moreC. vittatus in the area with a poor shell fit thanP. longicarpus.

Inhibition of larval barnacle attachment to bacterial films: An investigation of physical properties.

The effects of films of two strains of a marine bacterium, Deleya marina (ATCC 25374 and 27129) on the attachment response of cypris larvae of the balanomorph barnacle, Balanus amphitrite, were examined in the laboratory. Tests showed that the cell-surface hydrophobicities of the two bacteria in suspension were different. In contrast, films derived from these cells were both highly wettable (i.e., displayed high surface free energy). Assays (22 hours) compared permanent attachment of larval barnacles to films derived from exponential and stationary phase cells for both bacteria. These films either had no effect or inhibited attachment of both 0-day- and 4-day-old cypris larvae when compared with unfilmed controls. Our data indicate that inhibition of larval barnacle attachment by films of the two bacteria is the result of factors other than surface free energy. Production of chemical barnacle settlement inhibitors by the bacteria is hypothesized.