“Four machines for sod-seeding in comparison: first results of operational and technical tests in Basilicata”

Our study was carried out to evaluate four different seeders for sod-seeding by a qualitative and quantitative comparison of their performances on cereal crops in Basilicata. The application of sod-seeding, alias no tillage, it may represent a valid alternative to traditional seeding in areas with high cereal vocation, as a guarantee against production costs, safeguarding the productive and environmentalists aspects in the south of Italy, where there is a great crop specialization and higher environmental risk resulting from intensive farming operations. So, were organized tests with four different seeders: Gaspardo-Directa, Amazone AD 300, Alpego ASI 303 and Laseminasodo. We analysed the technical and operational characteristics of the seeders, the distribution regularity of the seed and the parameters concerning the harvesting. Relating to this study, the most important difference, between these machines we considered, was the coulter body. The results were interesting for all machines, the operational capabilities have been certified on values equal to 1,8 ha/h, satisfactory values regularity of longitudinal and transverse distribution of the seed considering that the value of plants emergency was close to 90%. About yield obtained, some data collected showed a higher value compared with that obtained with the traditional seeding in the same soil conditions

A revised diet matrix to improve the parameterization of a West Florida Shelf Ecopath model for understanding harmful algal bloom impacts

Harmful algal blooms (HABs) are a growing concern in the West Florida Shelf (WFS) region. An Ecopath with Ecosim (EwE) model of the WFS explicitly simulating HABs was previously developed to illuminate the potential impacts of blooms of the dinoflagellate Karenia brevis (colloquially referred to as “red tides”) on the WFS ecosystem. However, the diet matrix of the Ecopath component of this EwE model (referred to as “WFS-HAB Ecopath”) was based largely on sparse, cursory information and not on local survey data. Here, we revise the diet matrix of the WFS-HAB Ecopath model using predictions of a robust statistical model that incorporates local survey data and employs the Dirichlet distribution and maximum likelihood estimation. The relative impacts of both the revised diet matrix and red tide mortality scenarios on model structure are explored by comparing four alternative WFS-HAB Ecopath models: (i) the base model; (ii) a model employing the revised diet matrix; (iii) a model with elevated red tide mortality; and (iv) a model with both the revised diet matrix and elevated red tide mortality. Incorporating the revised diet matrix into the WFS-HAB Ecopath model had a relatively large impact on ecosystem structure (i.e., trophic organization, mortality rates, trophic interaction strengths, and omnivory). Elevated red tide mortality had virtually no impact on ecosystem structure aside from altering the contribution of fishing, natural, and red tide mortalities to the total mortality of functional groups; however, elevated red tide mortality might have meaningful implications in dynamic simulations, which should be explored in future studies. Collectively, results showed that incorporating the revised diet matrix into WFS-HAB Ecopath, which revealed a number of new predator-prey linkages, led to a more complex and interconnected food web. Specifically, prey items were generally consumed by a broader variety of predators, which contrasts with the base WFS-HAB Ecopath model where many prey, particularly juvenile fishes, were subjected to exceedingly high predation mortality rates from specific predators. The incorporation of the revised diet matrix into the WFS-HAB Ecopath model discussed herein is a fundamental step towards increasing the realism of trophic interactions in the model, which is particularly important as these trophic interactions define starting conditions for dynamic simulations.publishedVersio

Spatiotemporal Overlap Of Spiny Dogfish (Squalus Acanthias) And Commercial Fisheries In The Northeast Us Shelf Large Marine Ecosystem

Commercial fishermen have argued that localized concentrations of spiny dogfish (Squalus acanthias) in the northeast U.S. shelf large marine ecosystem (NES LME) have impeded their fishing operations when monitoring surveys estimated lower relative abundances. Fishery-dependent and -independent data were analyzed simultaneously to examine whether increased spatial overlap between spiny dogfish and commercial fisheries may explain high catches of this species on fishing grounds. Spatial overlap was quantified between spiny dogfish distribution and commercial fisheries from 1989 to 2009 during autumn and spring in the NES LME. Combined, the sink gillnet (SGN) and otter trawl (OT) fisheries accounted for the majority of spiny dogfish catch (autumn: 85%; spring: 92%), either retained (SGN) or discarded (OT). Centers of spiny dogfish abundance illustrated spatial differences in local density within the NES LME and revealed seasonal differences in spiny dogfish density. Recent increases in spatial overlap indicate that a growing portion of the spiny dogfish stock was available to each fishery over the time series. Availability, estimated as the percentage of spiny dogfish present on fishing grounds, also increased and was generally higher during autumn than spring. Abundance of mature (total length.80 cm) female spiny dogfish was significantly related to availability, but trends were variable between fisheries and seasons. Although recent increases in abundance indicate recovery, research regarding the mechanisms behind these changes may help explain why abundance in the NES LME appears highly variable

Identifying trade-offs and reference points in support of ecosystem approaches to managing Gulf of Mexico menhaden

Gulf menhaden (Brevoortia patronus) support the largest fishery by yield in the Gulf of Mexico (GoM) and are a key forage species for many marine predators. While menhaden stock assessments indicated that overfishing was not likely to have occurred in the past, concerns have been raised regarding the possible effects of menhaden fishing on their predators. In this study, we used a US Gulfwide Ecopath with Ecosim (EwE) model to explore the predicted effects of increased menhaden harvest on the GoM ecosystem and focused our analyses on Gulf menhaden predators. Key menhaden predators identified included king mackerel (Scomberomorus cavalla), Spanish mackerel (Scomberomorus maculatus), sea trout (Cynoscion spp.), red drum (Sciaenops ocellatus), and pelagic coastal piscivores [e.g., bluefish (Pomatomus saltatrix)]. As expected, these predators exhibited reduced biomass in response to increased Gulf menhaden harvest, with a predicted 11% decrease in predator biomass at simulated fishing levels near historical highs. Our results indicate strong relationships between the effects of menhaden fishing and the predator fishing mortality for king mackerel and intermediate relationships for Spanish mackerel, blacktip shark (Carcharhinus limbatus), red drum, large coastal sharks, and pelagic coastal piscivores. Biomass of predator groups such as demersal coastal invertebrate feeders [e.g., drums and croakers (Sciaenidae)] are more affected by menhaden harvest (through trophodynamics interactions and bycatch removal) compared to the isolated effect of their fishing mortality. For almost all the groups examined in the trade-off analysis, with the exception of sea trout, current biomass (2016) was higher than their target biomass representing 75% of their biomass at maximum sustainable yield. In comparison to the time series of fishing mortality rates estimated by the most recent Gulf menhaden stock assessment, the mean ecological reference point (ERP) of 0.862 was exceeded in all but 1 year from 1977 to 2007; however, neither the target nor threshold upper ERP value has been exceeded since 2008. The observed Gulf menhaden landings from 2003 to the present were generally within the range of the projected equilibrium landings (i.e., within confidence intervals) at both the ERP target and threshold values except for three recent years

Transient movements of a deep-water flatfish in coastal waters: Implications of inshore-offshore connectivity for fisheries management

1. Globally, small-scale inshore fisheries are being recognized as highly beneficial for underdeveloped coastal communities since they directly contribute to local economies. Community coastal fisheries, however, may target species that are simultaneously harvested by large commercial vessels in adjacent offshore waters, creating uncertainty over stock units and connectivity that complicate management. 2. Greenland halibut Reinhardtius hippoglossoides, a commercially important flatfish species in the Arctic, were tagged in Scott Inlet, coastal Baffin Island, Canada, with acoustic transmitters and tracked for a 1-year period. Our aim was to measure fish movement and connectivity between inshore habitats, where Inuit fisheries are developing, and offshore waters, where an established commercial fishery operates. Four movement metrics were established, and cluster analysis and a mixed effects model were used to define movement types and identify environmental covariates of the presence/absence within the coastal environment respectively. 3. Two distinct movement patterns were characterized for Greenland halibut; the majority were transients that were no longer detected inshore by the end of November (n = 47, 72%), and a smaller group of intermittently resident fish that moved into the offshore at the same time as transient fish, but returned to the coastal environment in the winter (n = 8, 12%), with the remainder being undefined. The presence of Greenland halibut in the inshore was negatively correlated with ice cover, indicating that fish moved offshore as sea ice formed. 4. Synthesis and applications. Greenland halibut were previously thought to be highly resident within the coastal environment of Baffin Bay; however, our data demonstrates that this is not true for all areas. In Scott Inlet and adjacent coastal regions, Greenland halibut exhibit complex inshore-offshore connectivity, suggesting inshore and offshore fisheries require a shared quota. We recommend that in the face of developing global small-scale coastal fisheries, improved understanding of stock connectivity between environments is required to sustainably manage commercial fish species

Characterizing ontogenetic habitat shifts in marine fishes: advancing nascent methods for marine spatial management.

Niche requirements and habitat resource partitioning by conspecific fishes of different sizes are significant knowledge gaps in the species distribution modelling domain. Management actions and operations are typically concentrated on static habitats, or specific areas of interest, without considering movement patterns of species associated with ontogenetic shifts in habitat usage. Generalized Additive Models were used to model the body length-habitat relationships of six fish species. These models were used to identify subsets of environmental parameters that drive and explain the continuous length-habitat relationships for each of the study species, which vary in their degree of ecological and/or commercial importance. Continuous predictive maps of the length distributions for each of the six study species across approx. 200 km(2) of the study area were created from these models. The spatial patterns in habitat partitioning by individuals of different body lengths for all six study species provide strong evidence for ontogenetic shifts. This highlights the importance of considering ontogenetic processes for marine spatial management. Importantly, predictive hotspot maps were created that identify potential areas that accumulate individuals of similar life stages of multiple species (e.g. multispecies nursery areas). In circumstances where limited resources are available for monitoring and management of fish resources, predictive modelling is a valuable tool for studying previously overlooked processes such as ontogenetic habitat shifts. Predictive modelling provides crucial information that elucidates spatial patterns in community composition across mosaics of benthic habitats. This novel technique can contribute to the spatial management of coastal fish and fisheries by identifying areas that are important for different life history stages of multiple fish species

Diel Variations in Survey Catch Rates and Survey Catchability of Spiny Dogfish and their Pelagic Prey in the Northeast US Continental Shelf Large Marine Ecosystem

This study examines the potential uncertainty in survey biomass estimates of Spiny Dogfish Squalus acanthias in the Northeast U.S. Continental Shelf Large Marine Ecosystem (NES LME). Diel catch-per-unit-effort (CPUE) estimates are examined from the Northeast Fisheries Science Center bottom trawl surveys conducted during autumn (1963-2009) and spring (1968-2009). Influential environmental variables on survey catchability are identified for Spiny Dogfish life history stages and five pelagic prey species: Butterfish Peprilus triacanthus, Atlantic Herring Clupea harengus, shortfin squid Illex spp., longfin squid Doryteuthis spp., and Atlantic Mackerel Scomber scombrus. Daytime survey catchability was significantly higher than nighttime catchability for most species during autumn and for mature male Spiny Dogfish, shortfin squid, and longfin squid during spring in the NES LME. For most stages and species examined, breakpoint analyses identified significant increases in CPUE in the morning, peak CPUE during the day, and significant declines in CPUE in the late afternoon. Seasonal probabilities of daytime catch were largely driven by solar zenith angle for most species, with stronger trends identified during autumn. Unadjusted CPUE estimates appear to overestimate absolute abundance, with adjustments resulting in reductions in absolute abundance ranging from 41% for Spiny Dogfish to 91% for shortfin and longfin squids. These findings have important implications for Spiny Dogfish regarding estimates of population consumption of key pelagic prey species and their ecological footprint within the NES LME

Utilizing individual fish biomass and relative abundance models to map environmental niche associations of adult and juvenile targeted fishes

Many fishes undergo ontogenetic habitat shifts to meet their energy and resource needs as they grow. Habitat resource partitioning and patterns of habitat connectivity between conspecific fishes at different life-history stages is a significant knowledge gap. Species distribution models were used to examine patterns in the relative abundance, individual biomass estimates and environmental niche associations of different life stages of three iconic West Australian fishes. Continuous predictive maps describing the spatial distribution of abundance and individual biomass of the study species were created as well predictive hotspot maps that identify possible areas for aggregation of individuals of similar life stages of multiple species (i.e. spawning grounds, fisheries refugia or nursery areas). The models and maps indicate that processes driving the abundance patterns could be different from the body size associated demographic processes throughout an individual's life cycle. Incorporating life-history in the spatially explicit management plans can ensure that critical habitat of the vulnerable stages (e.g. juvenile fish, spawning stock) is included within proposed protected areas and can enhance connectivity between various functional areas (e.g. nursery areas and adult populations) which, in turn, can improve the abundance of targeted species as well as other fish species relying on healthy ecosystem functioning

About the steel dog-bones in wooden beams

With regard to steel structures, the connections with reduced beam section (RBS) have been studied over the last 20 years, both from an analytical point of view and from an experimental point of view. Several experimental tests demonstrated that RBS connections designed according to the most modern seismic codes are able to obtain the desired goal: the protection of the connection due to the yielding of the adjacent RBS. In this paper, the possibility of using a steel RBS in a wooden beam is investigated. The main difference with respect to the case of a steel beam is due the different shape of plastic domain for steel and wood. In addition, while in a steel beam the yielding of an intermediate point of the beam can be accepted, in the case of a wooden beam this possibility is to be prevented. Furthermore, the role that vertical loads can play and the possibility that the beam to column connections are realized with a partial strength connection are analyzed and accounted for. The final goal of this study is the setup of new procedure, for wooden beams, for accurately computing the relation between steel RBS location, vertical load and amount of section reduction for ensuring that plastic hinges develop only in the in the reduced sections, i.e. only in the steel sectio