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SPATIAL AND SEASONAL PATTERNS IN SPECIES COMPOSITION AND OCCURRENCE OF FISH LARVAE IN THE AREA OF THE CANARY ISLANDS, EASTERN CENTRAL ATLANTIC

Regarding deep-water demersal and coastal fishes, the close affinity of the Canary Islands with the adjacent NW African coast, the Mediterranean outflow, the next-closest island Madeira, and seamounts in the immediate surroundings has been outlined (e.g. BRITO et al. 2006; LLORIS et al. 1991; UIBLEIN et al. 1999). Further studies that carefully integrate findings on fish distribution patterns and oceanographic conditions will certainly contribute to more detailed insights into both the small- and the large-scale zoogeography of the Canary Islands. Studies of fish larvae have particular relevance in this context, as they provide information on migration, colonization, and local recruitment patterns. Examples for the dependence of fish larval distribution on hydrographic features and how such features influence their community structures or distribution and affect the survival of single specimens are numerous (ACEVES-MEDINA et al. 2004; CHIH-HAO and TAI-SHEN 2002; FOCK and JOHN 2006; JOHN et al. 2001 and 2004b; LEIS 1986; LOBEL and ROBINSON 1988; LOGERWELL and SMITH 2001; SABATÉS and MASÓ 1992; SASSA et al. 2002 and 2004; SPONAUGLE et al. 2005). Since the Canarian Archipelago is a region of high hydrographic variability, it is highly interesting for studying fish larvae (BÉCOGNÉE et al. 2006; JOHN et al. 2004a; RODRÍGUEZ et al. 1999, 2001, 2004 and 2006) and to link the hydrographic features around the Canarian Archipelago to their distribution, especially regarding larvae with different habitats of origin. This study contributes to further knowledge of the diversity, abundance, and distribution of fish larvae in the Canary Island area based on examination of material collected during six pelagic cruises in the area.The main objectives are (1) to provide an annotated list of fish larvae taxa caught during these surveys, (2) to relate their distribution and abundance to oceanographic processes around the Canary Islands, and (3) to identify spatial and seasonal patterns in community structure and diversity. In order to provide sufficient background information for the discussion and conclusions to be drawn, the currently available information on the hydrographic situation around the Canarian Archipelago and the possible consequences for fish larvae abundance and diversity is reviewed in the section below.

1.2. OCEANOGRAPHIC CHARACTERIZATION OF THE AREA In general, the waters around the Canary Islands are oligotrophic and the autotrophic community is dominated by picoplankton, while the mesozooplankton is composed mainly of copedods (ARÍSTEGUI et al. 2001). Microheterotrophic organisms such as ciliates transfer the primary production to the higher trophic level of the mesozooplankton. Only a small proportion of the total primary production from larger cells (microplankton) is directly transferred to mesozooplankton herbivores (ARÍSTEGUI et al. 2001). A phytoplankton bloom and peak of primary production occurs in late winter in the investigated area, the so-called late winter bloom (LWB) seen in Figure 1a, d and f (ARÍSTEGUI et al. 2001; DAVENPORT et al. 2002). In addition to this LWB a local permanent increase in production around the islands can be observed then. This is a result of the perturbation of oceanic and atmospheric flows created by the islands themselves (SANGRA et al. 2001), as depicted in Figure 1a-f. Noteworthy, the chlorophyll distribution is not related to the mesozooplankton biomass distribution (ARÍSTEGUI et al. 2001). Particularly copepods, the main food source of fish larvae, are spatially negatively related to chlorophyll minima, with the highest abundance occurring at the margins of areas with high primary productivity (BARTON et al. 1998; CHIH-HAO and TAI-SHEN 2002). The peak in mesozooplankton abundance is temporally delayed from the phytoplankton peak, which as already mentioned before occurs from March to June (ARÍSTEGUI et al. 2001). This is caused by the prolonged duration of energy transfer into the higher trophic level of mesozooplankton via microheterotrophic organisms, as described above.

Inf. Téc. Inst. Canario Cienc. Mar. n°13

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Spatial and seasonal patterns in species composition of fish larvae in the Canary Islands  

Technical report consisting on a comprehensive annotated larvae taxa list with the most important taxonomic characters of this region

Spatial and seasonal patterns in species composition of fish larvae in the Canary Islands  

Technical report consisting on a comprehensive annotated larvae taxa list with the most important taxonomic characters of this region

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