Quantification of key biological processes determining the dynamics and the assessment of the anchovy population in the Bay of Biscay: growth, reproduction, demography and natural mortality.

333 p.

A survey of the northern neck of Virginia, being the lands belonging to the Rt. Honourable Thomas Lord Fairfax Baron Cameron, bounded by & within the Bay of Chesapoyocke and between the rivers Rappahannock and Potowmack: With the courses of the rivers Rappahannock and Potowmack, in Virginia, as surveyed according to order in the years 1736 & 1737.

Scale ca. 1:875,000.

Report of the Working Group for the Bay of Biscay and the Iberian waters Ecoregion (WGBIE). 13-19 May 2016, ICES HQ, Copenhagen, Denmark

The ICES Working Group for the Bay of Biscay and the Iberic waters Ecoregion (WGBIE) met in Copenhagen, Denmark during 13–14 May 2016. There were 22 stocks in its remit distributed from ICES Divisions 3.a–4.a though mostly distributed in Sub Areas 7, 8 and 9. There were 21 participants, some of whom joined the meeting re-motely. The group was tasked with conducting assessments of stock status for 22 stocks using analytical, forecast methods or trends indicators to provide catch forecasts for eight stocks and provide a first draft of the ICES advice for 2016 for fourteen stocks. For the remaining stocks, the group had to update catch information and indices of abundance where needed. Depending on the result of this update, namely if it would change the perception of the stock, the working group drafted new advice. Analytical assessments using age-structured models were conducted for the northern and southern stocks of megrim and the Bay of Biscay sole. The two hake stocks and one southern stock of anglerfish were assessed using models that allow the use of only length-structured data (no age data). A surplus-production model, without age or length structure, was used to assess the second southern stocks of anglerfish. No ana-lytical assessments have been provided for the northern stocks of anglerfish after 2006. This is mostly due to ageing problems and to an increase in discards in recent years, for which there is no reliable data at the stock level. The state of stocks for which no analytical assessment could be performed was inferred from examination of commer-cial LPUE or CPUE data and from survey information. Three nephrops stocks from the Bay of Biscay and the Iberian waters are scheduled for benchmark assessments in October 2016. The WGBIE meeting spent some time review-ing the progress towards the benchmark (see Annex 6) together with longer term benchmarks (2017 and after, see section 1.) for sea bass in the Bay of Biscay, all an-glerfish and hake stocks assessed by the WG. For the northern megrim stock, the sched-ule an inter-benchmark meeting was completed successfully and the group reviewed the outcome and accepted the category 1 update assessment. A recurrent issue significantly constrained the group’s ability to address the terms of reference this year. Despite an ICES data call with a deadline of six weeks before the meeting, data for several stocks were resubmitted during the meeting which lead to increased workloads during the working group, as in that case, the assessments could not be carried out in National Laboratories prior to the meeting as mentioned in the ToRs. This is an important matter of concerns for the group members. Section 1 of the report presents a summary by stock and discusses general issues. Sec-tion 2 provides descriptions of the relevant fishing fleets and surveys used in the as-sessment of the stocks. Sections 3–18 contains the single stock assessments.

Habitat selection and phenotypic diversity in the anchovy of the Bay of Biscay

Diversity among individuals in a population is an important feature linking vital rates with behaviour and spatial occupation. We measured the growth increments in the otolith of individual fishes collected on the annual fisheries survey PELGAS from 2001 to 2015. Individuals who grew larger at juvenile stage occupied later in life more off-shore habitats. Further, we analysed the allozymes of 13 different loci from 2001 to 2006. Alleles of the enzyme IDH showed different frequencies in inshore and offshore habitats. The population spatially segregates along a coast to off-shore gradient with individuals showing different early growth and allele frequencies. Results show how individuals in a population segregate spatially in different habitats in relation with phenotypic diversity. This implies modelling the population with individual-based and physiological approaches to fully grasp its dynamics. It also implies developing management strategies to conserve infra-population diversity as a means to garantee the occupation of the full range of habitats.

Water renewal mechanisms of the Bay of Algeciras in the Strait of Gibraltar

The Bay of Algeciras (BA) is a marine environment subject to high levels of anthropogenic pressure. Here we analyze observations collected at the Bay and the results of an ocean circulation model to investigate its circulation and variability. Special attention is paid to the identification of the mechanisms enhancing the exchange of water with the adjacent Strait of Gibraltar and therefore contributing to maintain satisfactory levels of water quality.

The polychaete worm Nereis diversicolor increases mercury lability and methylation in intertidal mudflats

The polychaete worm Nereis diversicolor engineers its environment by creating oxygenated burrows in anoxic intertidal sediments. The authors carried out a laboratory microcosm experiment to test the impact of polychaete burrowing and feeding activity on the lability and methylation of mercury in sediments from the Bay of Fundy, Canada. The concentration of labile inorganic mercury and methylmercury in burrow walls was elevated compared to worm-free sediments. Mucus secretions and organic detritus in worm burrows increased labile mercury concentrations. Worms decreased sulfide concentrations, which increased Hg bioavailability to sulfate-reducing bacteria and increased methylmercury concentrations in burrow linings. Because the walls of polychaete burrows have a greater interaction with organisms, and the overlying water, the concentrations of mercury and methylmercury they contain is more toxicologically relevant to the base of a coastal food web than bulk samples. The authors recommend that researchers examining Hg in marine environments account for sediment dwelling invertebrate activity to more fully assess mercury bioavailability.

Mercury and methylmercury bioaccumulation by polychaete worms is governed by both feeding ecology and mercury bioavailability in coastal mudflats

Polychaete worms are abundant in many mudflats but their importance to coastal food web Hg biomagnification is not known. We sampled sediments and polychaete worms from mudflats in the Bay of Fundy to investigate the bioaccumulation of mercury (Hg) and methylmercury (MeHg) in the coastal invertebrate food web. Hg concentrations in the sediments were low (<20 μg kg−1). Labile Hg (methanol/KOH sediment extraction) in surface sediments (0–1 cm) was positively correlated with Hg bioaccumulation by surface sediment-ingesting polychaetes but, surprisingly, there was a negative correlation between δ15N (i.e. trophic level) and THg bioaccumulation factors in polychaete worms. Worms feeding on deeper sediments contained the greatest MeHg concentrations (69.6 μg kg−1). Polychaetes are an important vector for Hg biomagnification to the coastal avian food web. This research demonstrates that feeding depth and method of feeding are more important than trophic position or sediment Hg concentrations for predicting Hg bioaccumulation.

Ensaios estereológicos e morfologia tridimensional na formação hipocampal de aves migratórias marinhas: análise quantitativa da imunomarcação seletiva de neurônios e micróglia em Calidris pusilla e Actitis macularia

É objetivo do presente trabalho implantar como modelos para estudo da formação hipocampal das aves migratórias as espécies de maçarico Calidris pusilla e Actitis macularia que abandonam as regiões geladas do Canadá, fugindo do inverno, em direção à costa da América do Sul e do Caribe onde permanecem até a primavera quando então retornam ao hemisfério norte. Mais especificamente pretende-se descrever a organização morfológica qualitativa e quantitativa da formação hipocampal, empregando citoarquitetonia com cresil violeta e imunomarcação para neurônios e células da glia, sucedidas por estimativas estereológicas do número total de células identificadas com marcadores seletivos para aquelas células, assim como comparar a morfologia tridimensional da micróglia das aves com a dos mamíferos. As coletas de campo para a caracterização da formação hipocampal do Calidris pusilla e Actitis macularia em seus aspectos morfológicos foram feitas no Brasil na Ilha Canelas (0°47'21.95"S e 46°43'7.34"W) na Costa da Região Nordeste do Pará no município de Bragança, e no Canadá, na Baia de Fundy perto de Johnson's Mills na cidade de New Brunswick (45°50'19.3" N 64°31'5.39" W). A definição dos limites da formação hipocampal foi feita empregando-se as técnicas de Nissl e de imunomarcação para NeuN. Para a definição dos objetos de interesse das estimativas estereológicas e das reconstruções tridimensionais empregou-se imunomarcação com anticorpo anti-NeuN para neurônios e anti-IBA- 1 para micróglia. As estimativas estereológicas revelaram em média número similar de neurônios nas duas espécies enquanto que no hipocampo de Actitis macularia observou-se número de micróglias 37% maior do que no de Calidris pusilla. Além disso, encontrou-se que em média o volume da formação hipocampal do Actitis macularia é 38% maior do que o encontrado em Calidris pusilla. Os estudos comparativos da morfologia microglial das duas espécies de aves com a dos mamíferos Rattus novergicus e Cebus apella revelaram diferenças morfológicas significantes que indicam que as micróglias das aves mostram em média, menor complexidade (dimensão fractal), tem diâmetros e perímetros de soma menores e possuem ramos mais finos do que aquelas do rato e do macaco.

Male-biased reproductive effort in a long-lived seabird.

Background: In dimorphic seabirds, the larger sex tends to provision more than the smaller sex. In contrast, monogamy and biparental care are often associated with equal effort between the sexes. However, the few studies that have tested sex-specific effort in monomorphic seabirds have primarily examined the details of foraging at sea. Hypotheses: Parental effort is also sex-biased in a monomorphic seabird mating system for one of two reasons: (1) If females enter the period of parental care less able to invest in care due to the cost of egg production, male-biased effort may be necessary to avoid reproductive failure. (2) Alternatively, female-biased effort may occur due to the initial disparity in gamete size, particularly in species with internal fertilization. Organism: Leach’s storm-petrel (Oceanodroma leucorhoa), a monomorphic seabird with true monogamy and obligate biparental care. Site: A breeding colony of Oceanodroma leucorhoa at the Bowdoin Scientific Station on Kent Island, Bay of Fundy, New Brunswick, Canada. Methods: Across multiple breeding seasons, we assessed incubation behaviour and chickrearing behaviour through one manipulative and multiple observational studies. We assessed energetic investment by inducing feather replacement and measuring the resulting rate of feather growth during both the incubation and chick-rearing phases of parental care. Conclusions: We observed male-biased effort. Males incubated the egg for a greater proportion of time than did females and, when faced with an egg that would not hatch, males continued to incubate past the point when females abandoned it. Males made a higher percentage of total food deliveries to chicks than did females, resulting in greater mean daily food provisioning by males than by females. During chick rearing, males grew replacement feathers more slowly than did females, indicating that males were more likely to reduce their own nutritional condition while raising chicks than were females. These results support the hypothesis that females enter the period of parental care at a nutritional deficit and males must compensate to avoid reproductive failure.