Trabajo presentado en el 39th CIESM Congress, celebrado en Venecia, Italia, del 10 al 14 de mayo de 2010

/pdf/biodiversity-of-the-mediterranean-sea-estimates-patterns-and-2mjs6mi5cx.pdf

Biodiversity of the Mediterranean Sea: estimates, patterns and threats

Aim To understand why and when areas of endemism (provinces) of the tropical Atlantic Ocean were formed, how they relate to each other, and what processes have contributed to faunal enrichment.



Location  Atlantic Ocean.



Methods  The distributions of 2605 species of reef fishes were compiled for 25 areas of the Atlantic and southern Africa. Maximum-parsimony and distance analyses were employed to investigate biogeographical relationships among those areas. A collection of 26 phylogenies of various Atlantic reef fish taxa was used to assess patterns of origin and diversification relative to evolutionary scenarios based on spatio-temporal sequences of species splitting produced by geological and palaeoceanographic events. We present data on faunal (species and genera) richness, endemism patterns, diversity buildup (i.e. speciation processes), and evaluate the operation of the main biogeographical barriers and/or filters.



Results  Phylogenetic (proportion of sister species) and distributional (number of shared species) patterns are generally concordant with recognized biogeographical provinces in the Atlantic. The highly uneven distribution of species in certain genera appears to be related to their origin, with highest species richness in areas with the greatest phylogenetic depth. Diversity buildup in Atlantic reef fishes involved (1) diversification within each province, (2) isolation as a result of biogeographical barriers, and (3) stochastic accretion by means of dispersal between provinces. The timing of divergence events is not concordant among taxonomic groups. The three soft (non-terrestrial) inter-regional barriers (mid-Atlantic, Amazon, and Benguela) clearly act as ‘filters’ by restricting dispersal but at the same time allowing occasional crossings that apparently lead to the establishment of new populations and species. Fluctuations in the effectiveness of the filters, combined with ecological differences among provinces, apparently provide a mechanism for much of the recent diversification of reef fishes in the Atlantic.



Main conclusions  Our data set indicates that both historical events (e.g. Tethys closure) and relatively recent dispersal (with or without further speciation) have had a strong influence on Atlantic tropical marine biodiversity and have contributed to the biogeographical patterns we observe today; however, examples of the latter process outnumber those of the former.

/pdf/atlantic-reef-fish-biogeography-and-evolution-q485371wug.pdf

Atlantic reef fish biogeography and evolution

Skates are arguably the most vulnerable of exploited marine fishes. Their vutlnerability is often as- sessed by examiningfisheries catch trends, but these data are not generally recorded on a species basis except in France. Aggregated skate catch statistics tend to exhibit more stable trends than those of other elasnmo- branch fisheries. We tested whether such apparent stability in aggregated catch trends could mask population declines of individual species. We examined two time series of species-specific surveys of a relatively stable skate fishery in the northeast Atlantic. These surveys revealed the disappearance of two skate species, long- nose skate (Dipturus oxyrhinchus) and white skate (Rostroraja alba) and confirmed a previously documented decline of the common skate (D. batis). Of the remaining five skate species, the three larger ones have de- clined, whereas twvo smaller species have increased in abundance. The increase in abundance and biomass of the smaller species has resulted in the stability of the aggregated catch trends. Becatuse there is significant di- etary overlap among species, we suiggest the increase in abundance of the smaller species ma) be due to com-

http://www.dulvy.com/uploads/2/1/0/4/21048414/dulvy_etal_2000_cb.pdf

Fishery Stability, Local Extinctions, and Shifts in Community Structure in Skates

Salmon lice, Lepeophtheirus salmonis, are naturally occurring parasites of salmon in sea water. Intensive salmon farming provides better conditions for parasite growth and transmission compared with natural conditions, creating problems for both the salmon farming industry and, under certain conditions, wild salmonids. Salmon lice originating from farms negatively impact wild stocks of salmonids, although the extent of the impact is a matter of debate. Estimates from Ireland and Norway indicate an odds ratio of 1.1:1-1.2:1 for sea lice treated Atlantic salmon smolt to survive sea migration compared to untreated smolts. This is considered to have a moderate population regulatory effect. The development of resistance against drugs most commonly used to treat salmon lice is a serious concern for both wild and farmed fish. Several large initiatives have been taken to encourage the development of new strategies, such as vaccines and novel drugs, for the treatment or removal of salmon lice from farmed fish. The newly sequenced salmon louse genome will be an important tool in this work. The use of cleaner fish has emerged as a robust method for controlling salmon lice, and aquaculture production of wrasse is important towards this aim. Salmon lice have large economic consequences for the salmon industry, both as direct costs for the prevention and treatment, but also indirectly through negative public opinion.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jfd.12061

Salmon lice--impact on wild salmonids and salmon aquaculture.

A hierarchical sampling design, spanning five orders of magnitude (from 10s of metres to 100s of kilometres) was created in order to quantify the multi-scale spatial variability of visually censused rocky reef fish assemblages in the western Mediterranean Sea. Specifically, we tested the hypotheses that species abundance and the biomass of reef fish populations is higher within than outside marine reserves, and that a north-to-south geographical gradient of these variables exists. We also explored the relationship between the fish assemblage and habitat structure, as an environmental factor likely to account for an important part of the observed variability. The mixed analyses of variance revealed that total abundance and biomass, species richness and abundance and biomass of several target species reached higher average values within marine reserves. Nevertheless, some non-protected localities (e.g. Aguilas) harboured richer and more abundant fish assemblages than some marine reserves. In addition, regional variation, attributable to differences in local carrying capacity and hydroclimatic conditions, are also shown across the studied area. Moreover, the studied assemblage is patchy at small and/or intermediate spatial scales, considering both assemblage descriptors (total abundance and biomass, species richness), and the abundance and biomass of fish species and spatial categories. Detected patterns were different depending on the species and assemblage variables analysed. Differences in habitat structure account for a significant proportion of total variability of the studied variables, and are likely to be responsible for a large part of the observed differences, especially at small-to-intermediate spatial scales. Other factors—spatial variability in larval distribution, settlement and/or post-settlement survival–are discussed in order to explain the observed differences. We concluded that causes of the observed patchiness of Mediterranean reef fish assemblages are probably multiple. Long-term, multi-scale spatial and temporal monitoring actions, as well as process-oriented manipulative experiments are urgently needed in order to ascertain the relative importance of each factor.

Multi-scale spatial heterogeneity, habitat structure, and the effect of marine reserves on Western Mediterranean rocky reef fish assemblages

Book reviewFishes of the North-eastern Atlantic and the Mediterranean: Volume II. P.J.P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen, E. Tortonese (Editors). UNESCO Press, Paris, 1986, pp. 510–1007, FF 250, Dfl 105.00, ISBN 92-3-002308-6

Fishes of the North-eastern Atlantic and the Mediterranean: Vol. 1. P.J.P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese (Editors). The Unesco Press, 1984, 510 pp., FF250, £37.50, $63.50, ISBN 92-3-002215-2

Niels Daan

Papers

Book reviewFishes of the North-eastern Atlantic and the Mediterranean: Volume II. P.J.P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen, E. Tortonese (Editors). UNESCO Press, Paris, 1986, pp. 510–1007, FF 250, Dfl 105.00, ISBN 92-3-002308-6

Fishes of the North-eastern Atlantic and the Mediterranean: Vol. 1. P.J.P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen and E. Tortonese (Editors). The Unesco Press, 1984, 510 pp., FF250, £37.50, $63.50, ISBN 92-3-002215-2