Interannual differences in growth and hatch‐date distributions of early juvenile European anchovy in the Bay of Biscay: implications for recruitment

In order to understand better the recruitment variability in European anchovy in the Bay of Biscay, it is important to investigate the processes that affect survival during the early life stages. Anchovy juvenile growth trajectories and hatch‐date distributions were inferred over a 3‐year period based on otolith microstructure analysis. Otolith growth trajectories showed a characteristic shape depending on their hatch‐date timing. Earlier‐born juveniles had notably broader maximum increments than later born conspecifics, resulting in higher growth rates. This observation suggests that early hatching would be beneficial for larval and juvenile growth, and, therefore, survival. The estimated juvenile hatch‐date distributions were relatively narrow compared with the extended anchovy spawning season (March–August) in the Bay of Biscay and indicated that only individuals originated mainly from the summer months (June–August) survived until autumn. Hatch‐date distributions were markedly different among years and seemed to influence the interannual recruitment strength of anchovy. We conclude that years characterized by juvenile survivors originating from the peak spawning period (May and June) would lead to considerable recruitment success. Downwelling events during the peak spawning period seem to affect larval survival. Furthermore, size‐dependent overwinter mortality would be an additional process that regulates recruitment strength in the anchovy population in the Bay of Biscay.     

Metabolism of permethrin isomers in American cockroach adults,house fly adults,and cabbage looper larvae

Forty-two insect metabolites of [1RS,trans]-and [1RS,cis]-permethrin are tentatively identified in studies with Periplaneta americana adults, Musca domestica adults, and Trichoplusia ni larvae involving administration of ¹⁴C preparations labeled in either the alcohol or acid moieties. The less-insecticidal trans isomer is generally metabolized more rapidly than the more-insecticidal cis isomer, particularly in cabbage looper larvae, and metabolites retaining the ester linkage appear in larger amount with cis-permethrin. Although the dichlorovinyl group effectively blocks oxidation in the acid side chain, the permethrin isomers are metabolized by hydrolysis and hydroxylation at the geminal-dimethyl group (either trans- or cis-methyl substituent) and the phenoxybenzyl group (predominantly at the 4′-position in all species but also at the 6-position in house flies). The alcoholic and phenolic metabolites are excreted as glucosides, and the carboxylic acids are excreted as glucosides and amino conjugates (glycine, glutamic acid, glutamine, and serine) with considerable species variation in the preferred conjugating moiety.     

Effects of temperature on development and mortality of Atlantic mackerel fish eggs

The development of Northeast Atlantic mackerel (Scomber scombrus) eggs, obtained from artificial fertilisation during the spawning season in the Biscay Bay area, was monitored at five temperatures (ranging from 8.6 to 17.8 °C). The times to intermediate stages (III–V) and total hatching, obtained in this study, agree with the results of previous studies undertaken some years ago. However, the times over stages IA, IB and 50% hatching indicate that development rates differed significantly between the studies; this could be related to an effect of the previous thermal history of the eggs, or to experimental biases. Daily mortality (Z) during the embryonic period was found to vary between 0.17 and 0.38, using traditional exponential decay models. The estimates of mortality rate were found to range consistently with those derived from previous studies on Northwest Atlantic mackerel eggs without predation. However, the shape of the survivorship-curve during the development pursued in this study has indicated that mortality is not constant in time. Similarly, the suitability of an exponential model to describe daily mortality should be considered.     

Southward re‐distribution of tropical tuna fisheries activity can be explained by technological and management change

There is broad evidence of climate change causing shifts in fish distribution worldwide, but less is known about the response of fisheries to these changes. Responses to climate‐driven shifts in a fishery may be constrained by existing management or institutional arrangements and technological settings. In order to understand how fisheries are responding to ocean warming, we investigate purse seine fleets targeting tropical tunas in the east Atlantic Ocean using effort and sea surface temperature anomaly (SSTA) data from 1991 to 2017. An analysis of the spatial change in effort using a centre of gravity approach and empirical orthogonal functions is used to assess the spatiotemporal changes in effort anomalies and investigate links to SSTA. Both analyses indicate that effort shifts southward from the equator, while no clear pattern is seen northward from the equator. Random forest models show that while technology and institutional settings better explain total effort, SSTA is playing a role when explaining the spatiotemporal changes of effort, together with management and international agreements. These results show the potential of management to minimize the impacts of climate change on fisheries activity. Our results provide guidance for improved understanding about how climate, management and governance interact in tropical tuna fisheries, with methods that are replicable and transferable. Future actions should take into account all these elements in order to plan successful adaptation.     

Variation components in leaf morphology of recruits of two hybridising oaks [<Emphasis Type="Italic">Q. petraea</Emphasis> (Matt.) Liebl. and <Emphasis Type="Italic">Q. pyrenaica</Emphasis> Willd.] at small spatial scale

Leaf morphological variation was examined in recruits of two hybridising oaks in a small sympatric area from Central Spain. Nuclear microsatellites were used to identify hybrids and assess the parental lineage. By Bayesian clustering analysis, 5% of hybrids were found. Principal component analysis was used to reduce 15 morphometric variables to four components associated with leaf size, lobation/pubescence and overall shape of the leaf. The percentage of variance due to genetic factors was evaluated through nested analysis of variance. As much as 70% of variance component was due to the factor “species” for lobation/pubescence, suggesting high adaptive value for these traits, possibly related to ecological constraints of the species. The genetic component of variance for leaf size and overall shape of the leaf was below 33%. Age and height of the recruits did not correlate with sun-leaf morphology. Competition indexes and diameter of the recruits showed slight, although significant, correlations with leaf size and lobation/pubescence components, pointing to some trade-offs between competition for light and leaf morphology of Q. petraea and Q. pyrenaica recruits.     

New hosts for Lecanosticta acicola and Dothistroma septosporum in newly established arboreta in Spain

A historical outbreak of needle blight disease was recorded during 2018 to 2019 in plantations of Pinus radiata and Pinus nigra in the North of Spain. The main pathogens involved in this historical outbreak were identified as Lecanosticta acicola and Dothistroma septosporum. Recently, a variety of tree species in three arboreta planted between 2011 and 2013 in the Basque Country as part of the European project REINFFORCE were showing symptoms of needle blight and defoliation. The aim of this study was to determine which pine species were affected with these pathogens. Tree species sampled included several provenances of P. brutia, P. elliottii, P. nigra, P. pinaster, P. pinea, P. ponderosa, P. sylvestris and P. taeda. Using molecular identification methods, Lecanosticta acicola was confirmed infecting Pinus brutia (Provenance: Alexandropolis, Greece and var. eldarica, Crimea) and represents a new host species for this pathogen. Pinus elliottii (Provenance: Georgia, USA) and P. ponderosa (Provenance: Central California, USA) are new host reports of L. acicola for Spain. Dothistroma septosporum was found for the first time on P. brutia (Provenance: Marmaris, Turkey) and P. ponderosa (Provenance: Oregon, USA) in Spain and was also detected infecting P. nigra (Provenance: Sologne Vayrières, France).