Scallop dredging has profound, long-term impacts on maerl habitats

Maerl beds are mixed sediments built by a surface layer of slow-growing, unattached coralline algae that are of international conservation significance because they create areas of high biodiversity. They are patchily distributed throughout Europe (to ∼ 30 m depth around the British Isles and to ∼ 120 m depth in the Mediterranean) and many are affected by towed demersal fishing. We report the effects of Newhaven scallop dredges on a previously unfished maerl bed compared with the effects on similar grounds that have been fished commercially in the Clyde Sea area, Scotland. Sediment cores were taken to assess the population density of live maerl thalli prior to scallop dredging on marked test and control plots. These plots were then monitored biannually over a four-year period. Live maerl thalli were sparsely distributed at the impacted site, and experimental dredging had no discernible effect on their numbers. The previously unfished ground had dense populations of live maerl and scallops (both Aequipecten opercularis and Pecten maximus). While counts of live maerl remained high on the control plot, scallop dredging led to a >70% reduction with no sign of recovery over the subsequent four years. The vulnerability of maerl and associated benthos (e.g., the delicate bivalve, Limaria hians) is discussed in relation to towed demersal fishing practices. © 2000 International Council for the Exploration of the Sea

Observations and possible function of the striking anterior coloration pattern of Galathea intermedia (Crustacea: Decapoda: Anomura)

Galathea intermedia is common, but cryptic, on Clyde maerl deposits where it lives in small groups of mixed sex and age, sharing shelters (typically dead Dosinia shells) to avoid predation. Its appearance is marked by six iridescent blue spots which may play an important role in intra- or interspecific interactions

An experimental study of the ecological impacts of hydraulic bivalve dredging on maerl

This paper describes the main characteristics of sardine schools detected in the Spanish-Atlantic surveys carried out from 1992 to 1997 (except 1994). A series of parameters were obtained for each school (morphological, positional and energetic) as well as environmental factors (temperature and salinity). The relationships between the school parameters were analyzed by a PCA and then the school parameters per se were described using both univariate and multivariate analyses (Box-plots, ANOVAs, MANOVA, and discriminant analysis). The results show that significant differences exist between years and geographic areas in that the Rías Baixas schools were smaller in size and of higher density than those from the Cantabric area. These differences could be related to the facts that the Rías Baixas is a nursery zone and sardine length and age are smaller than in the Cantabric Sea. It would seem that the differences in school morphology and energetic characteristics related to length and age of individuals allow us to distinguish between the sardine echo traces in this area. There is a high annual variability in the number of schools and this is not a function of either survey design or strategy and it is not related to the abundance estimates of sardine. These results are important for both future species identification and the improvement of survey design and strategy.

The impact of Rapido trawling for scallops, Pecten jacobaeus (L.), on the benthos of the Gulf of Venice

Rapido trawls are used to catch sole around the coast of Italy and to catch scallops in the northern Adriatic Sea but little is known about the environmental impact of this gear. Benthic surveys of a commercial scallop ground using a towed underwater television (UWTV) sledge revealed an expansive area of level, sandy sediment at 25 m characterized by high population densities of scallops (2.82 m-2 Aequipecten opercularis but fewer Pecten jacobaeus) together with ophiuroids, sponges, and the bivalve Atrina fragilis. Rapido trawls were filmed in action for the first time, providing information on the selectivity and efficiency of the gear together with its impact on the substratum and on the benthos. The trawls worked efficiently on smooth sand with ca. 44% catch rate for Pecten jacobaeus, of which 90% were >7 cm in shell height. Most organisms in the path of the trawl passed under or through the net; on average by-catch species only formed 19% of total catch by weight. Of the 78 taxa caught, lethal mechanical damage varied from 50% in soft-bodied organisms such as tunicates. A marked plot surveyed using towed UWTV before, then 1 and 15 h after fishing by Rapido trawl showed clear tracks of disturbed sediment along the trawl path where infaunal burrow openings had been erased. Abundant, motile organisms such as Aequipecten showed no change in abundance along these tracks although scavengers such as Inachus aggregated to feed on damaged organisms. There were significant decreases in the abundance of slow-moving/sessile benthos such as Pecten, Holothuria, and Atrina. Juvenile pectinids were abundant on the shells of Atrina. The introduction of a scheme of areas closed to trawling would protect highly susceptible organisms such as Atrina and enhance the chances of scallop recruitment to adjacent areas of commercial exploitation

Resistance to multi organ damage after hemorrhagic shock induced ischemia/reperfusion in arctic ground squirrels

•Worldwide hemorrhagic shock is the number one cause of death in trauma patients, the majority of those die from multi organ dysfunction syndrome [1, 2]. •During hemorrhagic shock (HS), the body undergoes global ischemia as blood pressure drops below the threshold at which tissues can be adequately perfused with blood. •Resistance to ischemic injury is a characteristic of hibernating mammals, including ground squirrels. •There is debate on if this resistance is dependant on hibernation season or if it is an intrinsic plasticity of the organism. QUESTION: Are AGS protected from HS‐induced ischemia reperfusion (I/R) injury on the whole organism and tissue–specific levels and if any protection is dependent upon their hibernation season.University of Alaska Fairbanks, Institute of Arctic Biology, Department of Chemistry and Biochemistr

Lexicase Selection Outperforms Previous Strategies for Incremental Evolution of Virtual Creature Controllers

Evolving robust behaviors for robots has proven to be a challenging problem. Determining how to optimize behavior for a specific instance, while also realizing behaviors that generalize to variations on the problem often requires highly customized algorithms and problem-specific tuning of the evolutionary platform. Algorithms that can realize robust, generalized behavior without this customization are therefore highly desirable. In this paper, we examine the Lexicase selection algorithm as a possible general algorithm for a wall crossing robot task. Previous work has resulted in specialized strategies to evolve robust behaviors for this task. Here, we show that Lexicase selection is not only competitive with these strategies but after parameter tuning, actually exceeds the performance of the specialized algorithms

Tilting relationalities: Exploring the world through possible futures of agriculture

Demography has driven increases in agricultural productivity and is in the limelight once again with questions about how we intend to feed 9 billion people on the planet. The scale of this challenge and the ecological threat from collapsing resources has generated a sense of impending crisis, but remarkably little action. The frames of reference tend towards climate change and the Anthropocene, but perhaps a more fruitful approach is to reflect on developments in agriculture and agroecology to examine the scale and significance of the ecological challenges we face. In this article, we use agriculture as a nodal point through which to engage with the emerging and dislocating human–planetary relations of the contemporary world, reflecting on past, current and future notions of ‘progress’, and on how ongoing developments and experiments in making a living with others (human, non-human and more-than-human others) might offer potential pathways for positive social transformation and future flourishing. As we argue throughout the article, reassessing notions of progress does not mean the mere return to traditional forms of knowledge and practice, nor embracing a form of luddite politics absent of advances in modern science and technology. Instead, we propose this is about opening spaces where diversity, pluralism and contending perspectives and agencies are engaged on their own terms, creating and sharing alternative knowledge and ways of doing and being. Here, the role for the social sciences and humanities is not to describe or pretend to represent these emerging relationalities, but instead to enable and actively engage them. Doing this responsibly and effectively will require us to inhabit the disorienting and discomforting ruins of progress, eschewing the turn towards finalised solutions and outcomes

When Specialists Transition to Generalists: Evolutionary Pressure in Lexicase Selection

Generalized behavior is a long standing goal for evolutionary robotics. Behaviors for a given task should be robust to perturbation and capable of operating across a variety of environments. We have previously shown that Lexicase selection evolves high-performing individuals in a semi-generalized wall crossing task–i.e., where the task is broadly the same, but there is variation between individual instances. Further work has identified effective parameter values for Lexicase selection in this domain but other factors affecting and explaining performance remain to be identified. In this paper, we expand our prior investigations, examining populations over evolutionary time exploring other factors that might lead to generalized behavior. Results show that genomic clusters do not correspond to performance, indicating that clusters of specialists do not form within the population. While early individuals gain a foothold in the selection process by specializing on a few wall heights, successful populations are ultimately pressured towards generalized behavior. Finally, we find that this transition from specialists to generalists also leads to an increase in tiebreaks, a mechanism in Lexicase, during selection providing a metric to assess the performance of individual replicates