Nursery value of Cystoseira forests for Mediterranean rocky reef fishes

10 páginas, 6 figuras, 1 tabla.The canopy-forming fucoid Cystoseira spp. provide biogenic structure, food and shelter for many organisms including fishes on Mediterranean nearshore rocky reefs. Infralittoral Cystoseira forests have declined or disappeared from many Mediterranean locales, leading to a severe transformation of the habitat and the loss of its tri-dimensional structure. Here we assess the nursery value of Cystoseira forests and the consequences of this habitat transformation on the recruitment of rocky reef fish assemblages. Densities of several reef fish juveniles—particularly Symphodus spp.—were 9 to 12 folds greater in Cystoseira forests than in other erect and turf algal assemblages. Experimental habitat manipulation mimicking the alteration of a Cystoseira canopy showed greater abundances of Symphodus spp. juveniles on artificially forested substratum than on bare substratum. Our study quantified for the first time the nursery value and functional importance of Cystoseira forests canopies suggesting that their loss may strongly affect the recruitment of littoral fishes in the Mediterranean Sea.This work is part of A.C.'s PhD thesis, and was conducted within the scope of the FOREFISH Project funded by the Total Foundation, from which we would like to thank Laure Fournier for her continued support.Peer reviewe

Seascape attributes, at different spatial scales, determine settlement and post-settlement of juvenile fish

Concern has increased in recent decades regarding processes influencing fish juvenile density distributions; indeed, juveniles determine the replenishment of populations and their habitats are often found in shallow coastal areas, where human impacts are concentrated. We aimed to measure the relative importance of seascape attributes at various spatial scales (from seascape to microhabitat) in fish settlement and post-settlement processes. Along the coast of Minorca Island (NW Mediterranean), Diplodus sargus settlement variability was higher among the southern coast compared to the variability in the northern one. Independently of coast location, sheltered nurseries presented lower settlement intensity and recruitment levels compared to exposed ones. Such patterns suggested differential larval supply according to exposure level. Furthermore, subsequent density-dependent post-settlement mortality reduced the cove-specific variability of initial settlement. In addition, inside each cove, juveniles displayed ontogenetic changes of microhabitat use: smaller juveniles were more abundant in the most heterogeneous microhabitat. Consequently, juvenile density distributions responded to seascape attributes at different spatial scales; this suggests that both lager scale attributes and microhabitat influence both settlement and post-settlement processes, and may be limiting for recruitment. Our study demonstrated the importance of a diversified seascape to promote fish population replenishmentVersión del edito

Management of Infralittoral Habitats: Towards a Seascape Scale Approach

International audienceThis study highlighted that the management of coastal fish assemblages still requires to upgrade and involve not only the approach of controlling catches but also in addition the management of all the essential habitats frequented during the different stages in the life cycle of these species. On the basis of a specific case study, the nurseries of the Sparidae fishes of the genus Diplodus (white seabream) in the area of the Calanques National Park (Marseilles; north-western Mediterranean), the present article proposes a conceptual scheme to guide coastal managers in following a seascape scale approach while using the tools they dispose of. This case study furthermore enables us to make practical recommendations applicable to the statutory and contractual management of the whole of the Mediterranean coastal zone

Submarine Landslides in French Polynesia

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The role of institutional quality in the international trade of a Latin American country: evidence from Colombian export performance

Abstract This paper analyses the relevance of Colombian institutional quality in recent years in terms of the performance of its exports within a framework of trade openness. Based on the trade gravity model, we examine the effect of governance on the evolution of Colombian exports through an econometric approach that identifies, on the one hand, the influence of institutional quality, and on the other hand, the influence of the institutional distance between Colombia and its trading partners. We use a panel data set for 2005–2018, through which the export flows from Colombia to 136 of its trading partners are considered. The findings indicate that Colombian institutional quality and the institutional distance between the country and its partners are statistically significant and affect its foreign sales. Similarly, there is a prominent influence of regulatory quality and the rule of law variables in the performance of Colombian exports in relation to other variables included in the model. We conclude that the Colombian government must improve its institutional quality considerably as a fundamental step towards boosting its overseas sales, not least because the country’s institutional distance from the world average is notable, which also affects its exports