Thermal reaction norms and the scale of temperature variation: latitudinal vulnerability of intertidal Nacellid limpets to climate change

The thermal reaction norms of 4 closely related intertidal Nacellid limpets, Antarctic (Nacella concinna), New Zealand (Cellana ornata), Australia (C. tramoserica) and Singapore (C. radiata), were compared across environments with different temperature magnitude, variability and predictability, to test their relative vulnerability to different scales of climate warming. Lethal limits were measured alongside a newly developed metric of “duration tenacity”, which was tested at different temperatures to calculate the thermal reaction norm of limpet adductor muscle fatigue. Except in C. tramoserica which had a wide optimum range with two break points, duration tenacity did not follow a typical aerobic capacity curve but was best described by a single break point at an optimum temperature. Thermal reaction norms were shifted to warmer temperatures in warmer environments; the optimum temperature for tenacity (Topt) increased from 1.0°C (N. concinna) to 14.3°C (C. ornata) to 18.0°C (an average for the optimum range of C. tramoserica) to 27.6°C (C. radiata). The temperature limits for duration tenacity of the 4 species were most consistently correlated with both maximum sea surface temperature and summer maximum in situ habitat logger temperature. Tropical C. radiata, which lives in the least variable and most predictable environment, generally had the lowest warming tolerance and thermal safety margin (WT and TSM; respectively the thermal buffer of CTmax and Topt over habitat temperature). However, the two temperate species, C. ornata and C. tramoserica, which live in a variable and seasonally unpredictable microhabitat, had the lowest TSM relative to in situ logger temperature. N. concinna which lives in the most variable, but seasonally predictable microhabitat, generally had the highest TSMs. Intertidal animals live at the highly variable interface between terrestrial and marine biomes and even small changes in the magnitude and predictability of their environment could markedly influence their future distributions

The role of biological interactions in modifying the effects of climate change on intertidal assemblages

The geographic distribution of most species is expected to alter as a consequence of global climate change. Predictions for the extent of these range shifts are frequently based on anticipated changes in temperature using a 'climate envelope' approach, which oversimplifies predictions because it does not consider interactions with other physical and biological factors. The aim of this thesis was to investigate how biological interactions modulate species responses to climate change. On many rocky shores in the NE Atlantic the interaction between limpets, barnacles and canopy forming macroalgae have an important role in structuring rocky shore communities. In particular, limpets control the abundance of macroalgae on the shore through their grazing activities. Through descriptive studies and manipulative experiments the behaviour of a northern/boreal species of limpet, Patella vulgata and a southern/lusitanian species of limpet, P. depressa were compared in relation to canopy forming algae (Fucus patches). As a result of differences in the spatial distribution, behaviour and grazing activity of these two species, if as predicted, there are changes in their relative abundance it is likely there will be implications for rocky shore community dynamics. The second part of my thesis investigated intra- and interspecific competition between two coexisting barnacle taxa with northern and southern centres of distribution. It is predicted that Increased warming will result in a reduction in the abundance of Semibalanus balanoides either as a direct result of increased temperatures or due to an increase in the number of poor spawning years. My results suggest that as a consequence of the gregarious nature of settling S. balanoides cyprids, recruitment success may be reduced irrespective of the numbers of cyprids in the plankton. This will result in more space becoming available for the competing and later settling Chthamalus spp, resulting in a change in barnacle population structure. The likely impacts of population changes and species range shifts in response to increased warming are discussed, with particular emphasis on how the interaction between limpets, barnacles and Fucus may alter. The implications of altered species interactions are then discussed in terms of the effects on community dynamics and ecosystem functioning. Finally the role of biotic interactions in modulating species responses to climate change are discussed with reference to the use of the 'climate envelope' approach in making predictions of species range shifts

Impacto de depredadores y niveles de recursos sobre rasgos fisiológicos de Fissurella crassa (Archeogastropoda

Indexación: Web of Science; RedalycThe effects of predators on the density of prey and their resources have been widely studied; however, there is little evidence on the effects of the predators in conjunction with the availability of resources on the traits of the prey, which could affect foraging activities. In this study, the physiological state and the escape response of the intertidal herbivore Fissurella crassa were evaluated in two sites which differ in terms of the abundance of its predator Heliaster helianthus. The results suggest that the escape response of F. crassa in the site with greater predator density and lower resource availability could require a better body condition that is compensated with increments in foraging. The results highlight the need to address the physiological perspective in community ecology in order to understand the interactions within these communities.Los efectos de los depredadores sobre la densidad de presas y sus recursos ha sido ampliamente estudiado, sin embargo existe escasa evidencia sobre los efectos de los depredadores en combinación con la disponibilidad de recursos relacionados con los rasgos de las presas que pueden afectar la actividad de forrajeo. En este estudio se evaluó el estado fisiológico y la respuesta de escape del herbívoro intermareal Fissurella crassa en dos sitios con diferencias en la abundancia de su depredador Heliaster helianthus. Los resultados sugieren que la respuesta de escape de F. crassa en el sitio de mayor densidad del depredador y baja disponibilidad de recursos, podría requerir una mejor condición corporal que se compensé con un incremento en el forrajeo. Los resultados destacan la necesidad de abordar la perspectiva fisiológica en ecología de comunidades para entender mejor las interacciones dentro de estas comunidades.http://www.redalyc.org/articulo.oa?id=5784430400

Anthropogenic Harvesting Pressure and Changes in Life History: Insights from a Rocky Intertidal Limpet

The importance of large breeding individuals for maintaining the health of marine fish and invertebrate populations has long been recognized. Unfortunately, decades of human harvesting that preferentially remove larger individuals have led to drastic reductions in body sizes of many of these species. Such size-selective harvesting is particularly worrisome for sequentially hermaphroditic species where the larger size classes are composed primarily of one sex. Whether these species can maintain stable sex ratios under sustained harvesting pressure depends on the level of plasticity of their life-history traits. Here, we show that populations of a marine limpet (Lottia gigantea) can adjust a fundamental aspect of their life history (the timing of sex change) when subjected to size-selective harvesting. As predicted by theoretical models, individuals from harvested populations change sex at smaller sizes and grow at slower rates compared to individuals from protected populations. In addition, the relative size at which the change from male to female occurs remains constant (?0.75; size at sex change/maximum size) across populations, regardless of harvesting pressure. Our results show that population-level demographic and life-history data, in conjunction with existing theory, can be sufficient to predict the responses of sequential hermaphrodites to harvesting pressure. Furthermore, they suggest such species can potentially adapt to size-selective harvesting

Exaptation and emergence as mechanisms to cross fitness valleys during evolution: an example using simulated homing behaviour

Evolution is often considered a gradual hill climbing process, slowly increasing the fitness of organisms. I investigate the evolution of homing behaviour in simulated intertidal limpets. In order to evolve path integration as a homing mechanism, a temporary reduction in an organism’s fitness is required – since high developmental costs occur before a successful homing strategy evolves. Simple hill-climbing algorithms, therefore, only rarely result in the evolution of a functional homing behaviour. The inclusion of a second behaviour (trail-following) greatly increases the frequency of success of evolution of a path integration strategy. Initially an emergent homing behaviour is formed combining path integration with trail following. This also demonstrates evolution through exaptation, since the original role of trail following is likely to be unrelated to homing. Analysis of the fitness landscapes of homing in the presence of trail-following behaviour shows a high variability of fitness, which results in the formation of ‘stepping-stones’ of high fitness across fitness valleys. By using these stepping-stones, simple hill-climbing algorithms can reach the global maximum fitness value

The utility of a digital simulation language for ecological modeling

Dynamic modeling of ecological phenomena has been greatly facilitated by the recent development of continuous system simulator programs. This paper illustrates the application of one of these programs, S/360 Continuous System Modeling Program (S/360 CSMP), to four systems of graduated complexity. The first is a two species system, with one feeding on the other, using differential equations with constant coefficients. The second and third systems involve two competing plant species in which the coefficients of the differential equations are varying with time. The final example considers the management of a postulated buffalo herd in which the dynamics of the herd population and composition by sex and age is combined with various strategies to control its size and to optimize buffalo production

Antibodies to glycans dominate the host response to schistosome larvae and eggs: Is their role protective or subversive?

Multiple exposures of chimpanzees to the radiation-attenuated schistosome vaccine provoked a strong parasite-specific cellular and humoral immune response. Specific IgM and IgG were directed mainly against glycans on antigens released by cercariae; these were also cross-reactive with soluble antigens from larvae, adult worms, and eggs. Egg deposition was the major antigenic stimulus after challenge of vaccinated and control chimpanzees with normal parasites, eliciting strong antiglycan responses to egg secretions. Glycan epitopes recognized included LacdiNAc, fucosylated LacdiNAc, LewisX (weakly), and those on keyhole limpet hemocyanin. Antibodies to peptide epitopes became prominent only during the chronic phase of infection, as glycan-specific IgM and IgG decreased. Because of their intensity and cross-reactivity, the antiglycan responses resulting from infection could be a smoke screen to subvert the immune system away from more vulnerable larval peptide epitopes. Their occurrence in humans might explain the long time required for antischistosome immunity to build up after infection

Mollusk freaks: New teratological cases on marine mollusks from the south pacific ocean

Indexación: Scopus.The present study provides new documented cases of abnormalities on chitons (hypomerism and coalescence of shell plates), in addition to four new cases on keyhole limpets (closed apical opening), and one new teratologic case on internal organs in octopuses (missing gill). We assess the frequency of these abnormalities and discuss about its possible environmental, mechanic and genetic causes. Several of these findings represent the first of these cases reported in South Pacific Ocean. © 2018, Escuela de Ciencias del Mar. All rights reserved.http://lajar.ucv.cl/index.php/rlajar/article/view/vol46-issue4-fulltext-

Biological surveys of Santa Monica Bay artificial reef and Topanga artificial reef

This report details the development of the biological communities on 2 artificial reefs off southern California (Figure 1). Santa Monica Bay Artificial Reef(SMBAR) and Topanga Artificial Reef(TAR) were both constructed in 1987 with 20,000 and 10,000 tons of quarry rock respectively. SMBAR was constructed in the manner of replication reefs which were designed by researchers to study the effects of environmental and structural variables on reef productivity in situ and TAR was built to promote kelp habitat. SMBAR is composed of 24 module pairs of varying height and rock size arranged along three depth strata while TAR was built in 3 piles along one depth strata (Table 1, Figure 2 & Figure 3). SMBAR is located at 34°00'47''N; 118°32'33" W approximately 5 nautical miles from the Marina del Rey entrance along a course of 290° magnetic. TAR is located at 34°01'38.10" N; 118°31'54.80"W; approximately 5.25 nautical miles from the Marina del Rey entrance along a course of 302° magnetic. The modules of SMBAR cover 3.58 acres of the 256 acres allotted in the permit. Each module has a footprint of about 0.07 acres. The modules of TAR cover 2 acres of 13 acres allotted in the permit. Each module has a footprint of about 0.70 acres. During the late fall of 1995 both reefs were surveyed by Department divers to assess how closely their biological communities had progressed towards a stable "equilibrium" community. Due to the relatively young age of the reefs and the rapid successional change which occurs in the associated biotic communities of new reefs (Carlisle et al. 1964; Turneretal. 1969; Carteretal. 1985; Matthews 1985; Solonsky 1985; Ambrose and Swarbrick 1989; Anderson et al. 1989; Hueckel and Buckley 1989; and WIlson et al. 1990), only qualitative surveys were conducted. (17pp.