The Green Wave: Reviewing the Environmental Impacts of the Invasive European Green Crab (Carcinus maenas) and Potential Management Approaches

The European green crab (Carcinus maenas), native to northwestern Europe and Africa, is among the top 100 most damaging invasive species globally. In some regions, including the Atlantic coast of North America, C. maenas has caused long-term degradation of eelgrass habitats and bivalve, crab, and finfish populations, while areas are near the beginning of the invasion cycle. Due to high persistence and reproductive potential of C. maenas populations, most local and regional mitigation efforts no longer strive for extirpation and instead focus on population control. Long-term monitoring and rapid response protocols can facilitate early detection of introductions that is critical to inform management decisions related to green crab control or extirpation. Once C. maenas are detected, local area managers will need to decide on management actions, including whether and what green crab control measures will be implemented, if local invasion might be prevented or extirpated, and if population reduction to achieve functional eradication is achievable. Due to the immense operational demands likely required to extirpate C. maenas populations, combined with limited resources for monitoring and removal, it is unlikely that any single government, conservation and/or academic organization would be positioned to adequately control or extirpate populations in local areas, highlighting the importance of collaborative efforts. Community-based monitoring, and emerging methods such as environmental DNA (eDNA), may help expand the spatial and temporal extent of monitoring, facilitating early detection and removal of C. maenas. While several C. maenas removal programs have succeeded in reducing their populations, to our knowledge, no program has yet successfully extirpated the invader; and the cost of any such program would likely be immense and unsustainable over the long-term. An alternative approach is functional eradication, whereby C. maenas populations are reduced below threshold levels such that ecosystem impacts are minimized. Less funding and effort would likely be required to achieve and maintain functional eradication compared to extirpation. In either case, continual control efforts will be required as C. maenas populations can quickly increase from low densities and larval re-introductions.

Telephone farmers and an emerging ecosystem are unlocking the hidden middle of agricultural value chains in Kenya through innovation

PurposeThis article explores the potential of an emerging group of farmers in Kenya, namely the growing segment of urban-based medium-size farmers, often called “telephone farmers”. To what extent do they benefit from an emerging ecosystem to support them in operating their farms, and what does that mean for the Hidden middle of agricultural value chains, the actors between the farmers and consumers? Unlocking the potential production of telephone farmers will require more services from collectors, traders, transport firms, the storage facilities, wholesalers and processing units and retailers. Ultimately, optimized telephone farm production benefits the business of Hidden middle value chain actors, increases incomes and jobs and improves food security.Design/methodology/approachBased on a survey and in-depth interviews a profile of the telephone farmers is given and their role as innovators is analyzed. The Latia Resource Centre (LRC) provides assistance to medium-size farmers, like the telephone farmers, helping them to prepare business plans and use modern technology and contributing to an emerging ecosystem providing support to all farmers.FindingsThe article analyzes the medium-size telephone farmers. It documents the contributions of this new agricultural actor to developing value chains and a dynamic ecosystem. The paper profiles the telephone farmers first and then identifies what they need and the support they receive. The emerging innovative ecosystem impacts agricultural productivity and production and hence the development of value chains. Small farmers gain access to opportunities offered by telephone farmers, working for them as outgrower or farm worker.Research limitations/implicationsThe authors used a small sample of 51 farmers and covered only a two-year period.Social implicationsSmall farmers are being helped through the emerging eco-system and farm labor acquire skills, which they can also you on another or their own farm.Originality/valueBased on the analysis an even more effective ecosystem is suggested and policy recommendations are formulated before the conclusion is drawn that these medium-size farmers contribute to innovation diffusion, inclusive value chain development and food security and are becoming part of this expanding, innovative ecosystem. Following the debate on food security the results suggest to pay more attention to the development of telephone farmers given their role in developing agricultural value chains and innovative ecosystems.

Serial invasions can disrupt the time course of ecosystem recovery

The impacts of species invasions can subside or amplify over time as ecosystems "adapt" or additional invaders arrive. These long-term changes provide important insights into ecosystem dynamics. Yet studies of long-term dynamics are rare, system-specific, and often confound species impacts with coincident environmental change. We track post-invasion changes shared across ecosystems and multiple decades, quantifying the response of seven key features to quagga and zebra mussels congeners that re-engineer and increasingly co-invade freshwaters. Six polymictic shallow lakes with long-term data sets reveal remarkably similar trends, with the strongest ecosystem impacts occurring within 5-10 years of zebra mussel invasion. Surprisingly, plankton communities then exhibited a partial, significant recovery. This recovery was absent, and impacts of initial invasion amplified, in lakes where quagga mussels outcompeted zebra mussels and more completely depleted phytoplankton. Thus, invasion impacts subside over time but can amplify with serial introductions of competing, even closely similar, taxa.

Ecosystem impacts by the Ancestral Puebloans of Chaco Canyon, New Mexico, USA

The Ancestral Puebloans occupied Chaco Canyon, in what is now the southwestern USA, for more than a millennium and harvested useful timber and fuel from the trees of distant forests as well as local woodlands, especially juniper and pinyon pine. These pinyon juniper woodland products were an essential part of the resource base from Late Archaic times (3000–100 BC) to the Bonito phase (AD 800–1140) during the great florescence of Chacoan culture. During this vast expanse of time, the availability of portions of the woodland declined. We posit, based on pollen and macrobotanical remains, that the Chaco Canyon woodlands were substantially impacted during Late Archaic to Basketmaker II times (100 BC–AD 500) when agriculture became a major means of food production and the manufacture of pottery was introduced into the canyon. By the time of the Bonito phase, the local woodlands, especially the juniper component, had been decimated by centuries of continuous extraction of a slow-growing resource. The destabilizing impact resulting from recurrent woodland harvesting likely contributed to the environmental unpredictability and difficulty in procuring essential resources suffered by the Ancestral Puebloans prior to their ultimate departure from Chaco Canyon.

Climate change and plant reproduction: trends and drivers of mast seeding change

Climate change is reshaping global vegetation through its impacts on plant mortality, but recruitment creates the next generation of plants and will determine the structure and composition of future communities. Recruitment depends on mean seed production, but also on the interannual variability and among-plant synchrony in seed production, the phenomenon known as mast seeding. Thus, predicting the long-term response of global vegetation dynamics to climate change requires understanding the response of masting to changing climate. Recently, data and methods have become available allowing the first assessments of long-term changes in masting. Reviewing the literature, we evaluate evidence for a fingerprint of climate change on mast seeding and discuss the drivers and impacts of these changes. We divide our discussion into the main characteristics of mast seeding: interannual variation, synchrony, temporal autocorrelation and mast frequency. Data indicate that masting patterns are changing but the direction of that change varies, likely reflecting the diversity of proximate factors underlying masting across taxa. Experiments to understand the proximate mechanisms underlying masting, in combination with the analysis of long-term datasets, will enable us to understand this observed variability in the response of masting. This will allow us to predict future shifts in masting patterns, and consequently ecosystem impacts of climate change via its impacts on masting. This article is part of the theme issue ‘The ecology and evolution of synchronized seed production in plants’.

Building the Digital Extended Specimen: A case study of invasive European frog-bit (Hydrocharis morsus-ranae L.)

The Extended Specimen was first described by Webster (2017). He defined a “constellation of specimen preparations and data types,” centered around an occurrence of an organism, which captures the breadth of empirical facts about an organism’s phenotype, genotype, and ecology in space and time. The Extended Specimen Network was embraced by the collections community in the Biodiversity Collections Network Extended Specimen Report (Lendemer et al. 2020) and the National Academies of Science, Engineering, and Medicine Future of Collections report (Lendemer et al. 2020, National Academies of Science, Engineering, and Medicine 2020). Several global discussions are underway to build a common definition of the Digital Extended Specimen (DES) and elucidate next steps in building the infrastructure to support Digital Extended Specimens and their network of associated data (including efforts among Distributed System of Scientific Collections (DiSSCo), Biodiversity Collections Network (BCoN), GBIF’s Alliance for Biodiversity Knowledge, TDWG's Task Group on Minimum Information about a Digital Specimen (MIDS), and others.) At the foundation of the DES is the occurrence of an organism in time and space, which is represented by physical specimens or observations serving as tokens of reality. Tokens are translated to digital records, which can be extended through a network of linkages between them and with derived and associated data, e.g. project methodologies, environmental conditions, habitat characteristics, and associated taxa. For digital records to be integrated with the larger network of Digital Extended Specimens, they must become FAIR digital objects that are Findable, Accessible, Interoperable, and Reusable (Wilkinson et al. 2016). By translating the Digital Extended Specimen concept to the local project scale, we provide opportunities to move beyond a theoretical understanding of the DES and towards a practical framework for its implementation. Here we present and discuss the power, limits, and questions in the implementation of the Digital Extended Specimen framework by applying it to the case study of an invasive aquatic plant in the Laurentian Great Lakes region. European frog-bit (Hydrocharis morsus-ranae L.; EFB) is native to western and northern Eurasia and invasive in North America and India. Dense mats of EFB may hinder commercial and recreational use of waterways and decrease light, dissolved oxygen, and native species diversity. We describe a multi-taxonomic study that examined EFB along with associated plant species, animal species, and environmental characteristics (Monfils et al. 2021). The integration of such diverse types of empirical data is a necessary prerequisite for determining the factors associated with EFB establishment, the impacts of EFB on native coastal wetland ecosystems, and the development of suitable management regimes for the conservation of native biodiversity. Data gathered from this study are housed in a local database. In our database, we consider both physical specimens and recorded observations as tokens of concrete occurrences of EFB, which define the base units. These tokens are linked to their collection events, which provide environmental and sampling context, as well as co-occurrences of other taxa including plants, invertebrates, fish, anurans, reptiles, and birds. Digitally linked, these extensions of each digital representation of a collected token provide not only empirical evidence of an EFB occurrence, but also directly connect it with all additionally sampled, derived, and associated information. Through this network of extensions we gain a more holistic understanding of EFB’s species associations, habitats, and ecosystem impacts at the level of populations and communities. The application of the Digital Extended Specimen framework at the project level illustrates how the DES can be used in a real-world context and highlights challenges in translating the concept from a theoretical to a practical perspective.