Assessing spillover from marine protected areas and its drivers: A meta‐analytical approach

Overfishing may seriously impact fish populations and ecosystems. Marine protected areas (MPAs) are key tools for biodiversity conservation and fisheries management, yet the fisheries benefits remain debateable. Many MPAs include a fully protected area (FPA), restricting all activities, within a partially protected area (PPA) where potentially sustainable activities are permitted. An effective tool for biodiversity conservation, FPAs, can sustain local fisheries via spillover, that is the outward export of individuals from FPAs. Spillover refers to both: “ecological spillover”: outward net emigration of juveniles, subadults and/or adults from the FPA; and “fishery spillover”: the fraction of ecological spillover that directly benefits fishery yields and revenues through fishable biomass. Yet, how common is spillover remains controversial. We present a meta‐analysis of a unique global database covering 23 FPAs worldwide, using published literature and purposely collected field data, to assess the capacity of FPAs to export biomass and whether this response was mediated by specific FPA features (e.g. size, age) or species characteristics (e.g. mobility, economic value). Results show fish biomass and abundance outside FPAs was higher: (a) in locations close to FPA borders (<200 m) than further away (>200 m); (b) for species with a high commercial value; and (c) in the presence of PPA surrounding the FPA. Spillover was slightly higher in FPAs that were larger and older and for more mobile species. Based on the broadest data set compiled to date on marine species ecological spillover beyond FPAs' borders, our work highlights elements that could guide strategies to enhance local fishery management using MPAs.     

Finding suitable growth models for turbot (Scophthalmus maximus L.) in aquaculture 1 (length application)

Growth data of two different commercial turbot (Scophthalmus maximus) strains reared in recirculating aquaculture systems were analysed with the aim to determine the most suitable model for turbot. To assess the model performance three different criteria were used: (1) The mean percentage deviation between the estimated length and actual length; (2) the residual standard error with corresponding degrees of freedom and (3) the Akaike information criterion. The analyses were carried out for each strain separately, for sexes within strains and for a pooled data set containing both strains and sexes. We tested a pre‐selection of six models, containing three to four parameters. Models were of monomolecular shape or sigmoid shape with a flexible point of inflection including the special case of monomolecular shape in defined cases of their parameters. The 4‐parametric Schnute model achieved best fit in 62% of all cases and criteria tested, followed by the also 4‐parametric generalized Michaelis–Menten equation in 48% and the 4‐parametric Janoschek model (38%). The von Bertalanffy growth function achieved only 29%, Brody 24% and a new flexible function 19% best fit. In a 1–1000 day growth‐simulation sigmoid shaped curves were produced by the Schnute model in 71% of cases. The Janoschek and the Michaelis–Menten model each produced sigmoid curves in 57% of all cases. This indicates that a flexible 4‐parametric function reflects the growth curve of turbot the best and that this curve is rather sigmoid than monomolecular shaped.     

Translocation of cave fish (Poecilia mexicana) within and between natural habitats along a toxicity gradient

During ecological speciation, diverging taxa have the potential to remain in close spatial proximity (i.e., sympatry or micro‐allopatry) theoretically allowing for continued contact and gene flow. In a system where incipient speciation of populations of the Atlantic molly (Poecilia mexicana) appears to be driven by abiotic factors, we investigated whether one of these factors, hydrogen sulphide (H₂S) toxicity, also constitutes an effective barrier to slow migration within and between habitats. We addressed this experimentally by translocating individuals from high toxicity to lower toxicity within a toxic cave and by translocating individuals from the toxic cave to a nontoxic surface habitat. Using a stepwise‐backwards Cox regression, we found that overall mortality was low, but statistically significant mortality occurred when individuals were transferred from higher toxicity to lower toxicity. In addition, only males were negatively affected by being transferred from low levels of toxicity to nontoxic, surface waters. This indicates that in addition to abiotic factors, other mechanisms, like predation and sexual selection, must be important in maintaining population separation.     

Development of new real-time PCR methods for detection of Decapod iridescent virus 1 in shrimp

Novel Decapod Iridescent virus (DIV1) infections emerged in mainland China around 2014 and have devastated shrimp aquaculture operations in Chinese coastal provinces. In 2020, DIV1 has spread to Taiwan with devastating results to shrimp and crayfish farms, in addition to being found in wild caught Penaeus monodon from the Indian Ocean. This trend is a major cause for concern and an urgent reminder to expand the tools needed to monitor the spread of DIV1 globally. Here, we describe a set of four different real-time polymerase chain reaction (PCR) assays positioned across the genome of DIV1 to detect the virus in shrimp tissues. All four assays show a wide dynamic range and high analytical sensitivity and specificity. In addition, the newly developed assays show excellent diagnostic sensitivity and specificity in clinical Litopenaeus vannamei samples of North Asian origin. The new molecular toolset will enhance global capabilities to monitor the spread of DIV1 and ultimately be used as an early warning system for farmers and authorities to engage in appropriate risk mitigation strategies.     

Taxonomy and evolution of cultivated plants: Literature review 1983/1984

Summary Important papers on taxonomy and evolution of cultivated plants published in 1983 and 1984 were complied and briefly discussed.

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Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1983/1984

Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1983 und 1984 wurden zusammengestellt und kurz kommentiert.

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: 1983–1984

, 1983 1984 . .

     

Retention of Ni,Zn and Cd by Si-associated goethite

Synthetic goethite used to study the effects of reaction time and temperature on the pH-dependent sorption of Ni, Zn and Cd was associated with amorphous silica. Ni interacted with dissolved Si and formed a Ni/Si precipitate on the goethite surface. Individual metals added at a concentration of 0.5 μmol g^?1 and sorbed during a reaction period of 504 hours (21 days) at 35°C were extracted by 0.7 M HNO₃ for 14 days. At the end of this period 11,28 and 40 percent of Ni, Cd and Zn, respectively, were not extracted whereas 20 percent of the total Fe content of the goethite and 39 percent of the associated Si were dissolved. During the sorption process metals became immobilized in the goethite particles. This effect can be related to a diffusion of metal ions into micropores. A total mobilization of sorbed metals can only be achieved by a complete dissolution of the goethite. The strong fixation of Ni, Zn and Cd by goethite suggests that additions of this Fe oxide could be used to ameliorate highly contaminated sludges or soils.     

Double sampling for stratification in periodic inventories—Infinite population approach

Double sampling for stratification is a sampling design that is widely used for forest and other resource inventories in forest ecosystems. It is shown that this sampling design can be adapted to repeated inventories including estimators of net change, even for non-proportional allocation of second-phase units and periodically updated stratification. The method accounts for the transition of sampling units among strata. Moreover, it may outperform classical single phase designs if sample plots are appropriately allocated to strata with respect to predefined target variables, here: volume per ha of bigger trees of the main tree species. The latter requires a clear definition of predominant aims of the inventory and an appropriate optimization method. Access to inventory data of a state forest district from two occasions allowed for an optimization of the design based on the first occasion, which proved to be still advantageous on the following occasion. Estimators are developed under the infinite population approach, which is generally deemed more appropriate for forest inventories.     

Entwicklung der Niederschlags-Deposition von Schwermetallen in Westdeutschland. 2. Arsen,Chrom, Kobalt und Nickel

Development of heavy-metal deposition by precipitation in West Germany. 2. Arsenic, chromium, cobalt, and nickel Between 1984 and 1993 the deposition of As, Cr, Co and Ni with bulk precipitation was measured on 6 open field sites in Northrhine-Westphalia/Germany. The absolute amount of As, Cr, Co and Ni deposition varies according to field sites and annual precipitation. In all studied areas, however, As deposition with bulk precipitation decreased significantly during the observation period. Considering all research stations under study, the average As deposition fell from 11.0 g ha^?1 in 1984 to 3.0 g ha^?1 (r = ?0.982***). The reduction in As deposition corresponds with the reduction in As emission within the same period of time prognosticated. Immission of Cr and Co also decreased significantly over the majority of the studied areas. The avarage Cr immission fell from 8.5 g ha^?1 in 1984 to 3.5 g ha^?1 in 1993 (r = ?0.888***), whereas the average Co immission decreased from 2.6 g ha^?1 to 1.1 g ha^?1 (r = ?0.869***). In contrast, no reduction in Ni deposition with precipitation was found on any of the studied areas under observation. Co shows the lowest deposition rates. On average, 2.2 times as much Cd, 2.7 times as much As, 3.2 times as much Cr, 6.5 times as much Ni, and 66 times as much Pb was deposited on the six open field sites in Northrhine-Westphalia in 1993.