Actinoptychus splendens (Shadbolt) Ralfs (Bacillariophyceae): a biostratigraphic marker for the later part of the Holocene coastal deposits along the southern North Sea

Actinoptychus splendens is a conspicuous and widely distributed marine diatom. At present it is common in the coastal waters of the southern North Sea, but it appears to be absent in the older Holocene deposits along the Dutch and Belgian coasts. Its first postglacial appearance here can be dated at between 4400 and 4100 BP. By 3800 BP it is well established in the region. Although generally not abundant, it can be found in nearly every sample of younger marine or brackish deposits. The large amount of material investigated from the area, as well as the high preservation potential and easy recognition of the species, preclude any other explanation for its apparent absence along southern North Sea shores prior to ±4100 BP, than a late natural immigration. This appears to be quite exceptional, all the common species which generally occur in association with A. splendens being present from the onset of Holocene sedimentation. A. splendens may become an important marker taxon in the Holocene stratigraphy of the coastal plains along the southern North sea.     

Discards in bottom‐trawl fishery in the western Black Sea (Turkey)

The aim of this study was to estimate the discards of target and non‐target species from bottom trawlers (rhombic and 40 mm cod end mesh size nets) in the Black Sea. On‐board sampling was conducted on the southwestern coasts of the Black Sea in the fishing ports of Rumelifeneri and Igneada for a total of 66 hauls on two commercial bottom trawlers from October 2012 to April 2013 and from October 2013 to April 2014. A total of 32 species were captured, including 25 species of fish, three crustacea, two echinodermata and two mollusca. Mullus barbatus and Merlangius merlangus euxinus were the target species, whereas 24 species were always discarded. Scophthalmus maximus and Pomatomus saltatrix were always retained. The two regions were similar in terms of catch and discard compositions, CPUE, DPUE and discard ratio. Discarding is important in the Black Sea commercial bottom trawl fishery and accounts for as much as 31.4% of the total bottom trawl catch. The results showed that the discard rates varied among species, depths (p = .04) and seasons (p = .0001). Finally, it was concluded that in the western Black Sea, when the impacts of depth and season are considered, that the discard quantity can be reduced.     

Discards in bottom trawl fishery in the Aegean Sea (Izmir Bay,Turkey)

Sampling was carried out on a seasonal basis during 2007–2009, using a conventional bottom trawl net with 44 mm codend mesh size in Izmir Bay, Aegean Sea. A total of 116 valid hauls: 27 in autumn, 28 in winter, 35 in spring and 26 in summer, were conducted at depths ranging from 30 to 70 m. A total of 112 species: 15 Chondrichthyes, 83 Osteichthyes, 11 Cephalopoda and 3 Crustacea were obtained in the trawl codend. All captures were separated into commercial (C) and non‐commercial (NC) species. The C ratio was 69.6%, while NC (i.e. discards) was 30.4%. Diplodus annularis was the most abundant species in all seasons, followed by Mullus barbatus, Merluccius merluccius, Citharus linguatula, Serranus hepatus, Lepidotrigla cavillone, Spicara maena, Myliobatis aquila, Diplodus vulgaris, and Trisopterus minutus in decreasing order of abundance. These top ten species constituted 75% of total catch weight. Biomass ratios of total discards to commercial species were 0.44 : 1.     

Environmental assessment of common octopus (Octopus vulgaris) from a small-scale fishery in Algarve (Portugal)

The International Journal of Life Cycle Assessment - Common octopus is the fishing species with highest economic revenue in Portugal, and its consumption per capita is very high. The majority of...     

By-catch and discarding practices in five Algarve (southern Portugal) métiers

The catches and discards of trawlers, seiners and trammel netters were studied in the Algarve (southern Portugal) using observers onboard commercial fishing vessels. Species diversity was high, with 236 species recorded as occasionally, frequently or regularly discarded. Mean discard rates per trip were 0.13, 0.20, 0.27, 0.62 and 0.70, respectively, for trammel nets, demersal purse seines, pelagic purse seines, fish trawls and crustacean trawls, with high variability in terms of discard volume and discard rate. This was especially so for seiners where from 0 to 100% of the total catch might be discarded. No significant relationships were found between discard quantity or discard rate and characteristics of the fishing vessels sampled within each métier (total length, TAB, hp, kW). Based on the above discard rates and the official landings, it was estimated that in 1996, Algarve trawlers discarded 9000–13000 tonnes (t) while seiners discarded 5500–8200 t. Discarding practices in these fisheries are reviewed and the reasons for discarding are presented by species and métier basis. The results support the need for more studies on the factors contributing to discarding, variability in discard quantities and rates, the fate of discards and their importance to the marine ecosystem, and on ways of reducing by-catch and discarding in these fisheries.     

Paleolimnology of mid-elevation lakes in the Kenya Rift Valley

Three small lakes of the Kenya Highlands have been subject to intermittent paleoenvironmental investigation for more than 50 years. In this report, the stratigraphic, core-based history of Lake Naivasha (elev. 1 890 m) is extended backward to 20 000 B.P. and is related to less complete 30 000-year core stratigraphies from nearby lakes Nakuru and Elmenteita. The paleolimnological reconstructions, primarily diatom-based, include geochemical parameters and the first ostracode stratigraphies from tropical Africa. The analyses from all three lakes converge on a history of low and fluctuating water levels over approximately the past 4 500 years, preceded by a major Holocene high stand (ca. 10 000-6 000 B.P.) and a brief earlier rise centered on 12 500 B.P. The lakes were mostly very low during the late Pleistocene (13 000–30 000 B.P.), though modestly elevated levels may have occurred early in this time period. The ostracode record, comprising at least 15 species, was relatively continuous in the Nakuru core but was restricted to sharply demarcated regions in cores from the other lakes.     

Effect of depth and reef structure on early macrobenthic communities of the Algarve artificial reefs (southern Portugal)

This study was carried out on the “Faro/Ancão” artificial reef (AR), located off Faro, deployed in May 2003. We aimed to characterise early macrobenthic community colonisation of two concrete AR groups located at different depths (16 m and 20 m depth) and to test the effect of reef structure on these communities. The non-colonial organisms were counted; barnacles and colonial species were quantified using biomass. Multivariate analyses indicated that early macrobenthic communities (6 months of immersion) were affected by depth, and that barnacles and colonial species were also affected by reef structure. Univariate analyses showed that the biomass of barnacles and colonial species was significantly different among reefs and layers of modules. Both AR groups were characterised by the species Balanus amphitrite, Gregariella subclavata, Musculus cf. subpictus, Paleanotus cf. bellis and Syllidia armata. Jassa marmorata and Bugula neritina were characteristic species at 16 m depth, particularly on the AR Upper layer of modules, whereas Anomia ephippium was particularly common at 20 m, especially on the Lower layer of modules.     

A fourteen-year overview of the fish assemblages and yield of the two oldest Algarve artificial reefs (southern Portugal)

Artificial reefs have been deployed worldwide for the last three decades in response to problems concerning coastal resources, ecosystems and fisheries. In many countries they have became important elements of integrated fisheries management plans. In Portugal two artificial reef systems (ARSs) were deployed by the Portuguese Institute of Marine Research (IPIMAR) in 1990, in the southern coast (Algarve). They were located off Faro and Olhão, over different sea-bottom types and located at different distances from the coastline. To analyse the effect of ARSs deployment on local fish assemblages and to evaluate their effectiveness in terms of mean fishing yields and mean number of species caught, fishing surveys have been conducted over 14 years (256 net sets) using a gillnet to sample the ARS of Faro and Olhão and respective control sites. The fishing yields from the ARs continually exceeded those from the control sites, in both the mean number of species caught and the mean CPUE in weight (1.8–2.6 times); both were higher at Faro. Moreover, the comparison between fish assemblages from the ARS and respective control sites showed that the deployment of the man-made structures did not change the composition of the fish assemblages caught by the gill nets, or the equilibrium of the community, since the relative proportion of the different functional groups of fish remained stable. The ARSs are a useful management tool on the Algarve coast, enhancing and diversifying the catches, thus contributing to improved local artisanal fisheries, which play a major role in this region.     

Environmental changes clarified by pollen and diatom proxy records in the sedimentary archive of the northwestern Japan Sea during last 21.0 kyr

High-temporal resolution pollen and diatom records from the northwestern Japan Sea document environmental changes over the last 21.0 kyr. Vegetation and climate changes were evaluated using the forest-steppe (SFI) and the pollen temperature (T_p) indices. The highest SFI occurred between ca. 21.0 ka and 16.6 ka and indicates the presence of a relatively dry climate and large areas of forest-steppe in the region. Boreal forests covered the mountain slopes. The broad-leaved trees survived in refugia located in lower mountain belts. Beginning ca. 16.6 ka, SFI decreases, while T_p increases, especially between ca. 11.0 ka and 5.7 ka. However, variations in these indices indicate fluctuating climates during the deglaciation. Significant vegetation changes occurred in the Holocene. Mixed deciduous forests with a predominance of Quercus became widely present beginning ca. 9.8 ka. The area of forest-steppe was reduced occurring only in local habitats. Pinus became one of the most common taxa in the forest ca. 5.3 ka. The geographic features of the coring area have determined in the past the persistence throughout the record of cold-water diatom flora. Cold-water diatoms have dominated in both cool and warm intervals; however, a small increase in the percentage and species diversity of warm-water diatoms was noted for warming. Low sea level during the Last Glacial Maximum (LGM) and early Holocene changed the general patterns in the sea circulation and in the vectors of the longshore currents, which transported the waters formed in the shallow areas of the northeastern and northern parts of the Japan Sea. A slight increase in sublittoral benthic diatoms indicates a lowered sea level during the LGM. The increase in sublittoral planktonic diatoms reflects a gradual rise in sea level during the Bølling–Allerød (BA) and Younger Dryas (YD). A greater component of oceanic diatom species at Holocene indicates the inflow of Pacific waters across both the Tsushima and Tsugaru straits. This study of pollen and diatom records demonstrates a clear response to climatic fluctuations and sea level changes in the Japan Sea during the Late Pleistocene and Holocene.     

A giant vampire (Mammalia, Chiroptera) in the Late Holocene from the Argentinean pampas: paleoenvironmental significance

The first fossil desmodontine record and the only well documented chiropteran fossil record from Argentina is described. A complete left upper canine was collected at Centinela del Mar (38°21′S58°W, General Alvarado County, Buenos Aires Province) from fossil-bearing sediments referred to the Late Holocene. The tooth size is 25% larger than that of the modern vampire bat, Desmodus rotundus. We assign this tooth to Desmodus cf. D. draculae, an extinct species recorded in the Pleistocene–Holocene of South America (Brazil and Venezuela). The southernmost distribution of present-day Desmodus extends to northeast Buenos Aires province (35°S). The presence of Desmodus some 600 km south of this present-day limit (July minimal isotherm of 10°C) indicates that around 300 years BP the southeastern Buenos Aires province was at least 2°C higher than modern July isotherm. The Desmodus tooth is associated with sigmodontine rodents characteristic of subtropical and temperate-warm areas (e. g., Pseudoryzomys simplex, Bibimys cf. B. torresi), and provides additional evidence to support this hypothesis. A correlation with a global warming phase is discussed.     

A change in the distribution pattern of diatoms above and below the halocline in bottom sediments of the central Arkona Basin,southern Baltic

Surface sediment samples from the central Arkona Basin, southern Baltic, were investigated by diatom analysis. The samples, taken by a Niemistö sampler, included the sediment-water interface and about 2–3 centimetres of the very water-saturated sediment. The samples represent the sediments deposited in the transition layer of the halocline in the Arkona Basin and immediately above and beneath it. The distribution pattern of diatoms and diatom pieces changed, reflecting the position of the halocline.Diatom analysis is an important tool in identifying Holocene Baltic sediments, and the knowledge of recent hydrological and chemical factors and their impact on the distribution pattern of diatoms is one way to evaluate the usefulness of diatom records in postglacial Baltic marine sediments. The surface-sediment diatom assemblages can be compared with the data from postglacial Baltic offshore cores. They give prelimary indications where diatom records from Littorina or Yoldia stages could be expected.     

Size at sex change and reproductive cycle of the limpets Patella vulgata and Patella ulyssiponensis (Mollusca: Patellogastropoda) from intertidal rocky shores of the Algarve coast (southern Portugal)

ABSTRACT

This study describes the reproductive cycle of the common limpet (Patella vulgata) and rough limpet (Patella ulyssiponensis) from the Algarve coast (southern Portugal). Individuals of both species were sampled monthly during two consecutive years, and subjected to gonad histology and calculation of the mean gonadal index (GI). Both species had balanced sex ratios (P. vulgata = 1M: 0.98F; P. ulyssiponensis = 1M: 1.03F), similar size-frequency distribution between sexes, and equivalent mean shell lengths (SL) and total weights (TW) between males and females. In these protandrous hermaphrodites, the estimated size at sex change was slightly smaller in P. vulgata (SL₅₀ ≈ 29 mm) than in P. ulyssiponensis (SL₅₀ ≈ 36 mm). The reproductive cycles of both species were characterised by a main spawning season in early spring to early summer, sometimes including subsidiary spawning events. A comparison of the main spawning season throughout the species distributional ranges revealed that populations of P. vulgata and P. ulyssiponensis from southern Portugal have later spawning periods than other populations from the northeastern Atlantic Ocean. The present information is relevant for conservation purposes and for the proposal of management measures for the harvesting activity targeting P. vulgata and P. ulyssiponensis in southern Portugal.     

Spatial and depth-associated distribution patterns of shallow gorgonians in the Algarve coast (Portugal, NE Atlantic)

The ecological role of gorgonians for marine rocky bottoms is worldwide recognized, but the information on the distribution patterns of NE Atlantic temperate species is insufficient, considering current global, regional and local threats. To overcome the lack of information on the spatial distribution patterns of gorgonians in south Portugal, in 2009/2010, the occurrence and abundance of gorgonian species in rocky bottoms were quantified over more than 25 km of coast (37.1°N/8.6°W) down to 30 m depth. Eunicella labiata, Eunicella gazella, Eunicella verrucosa and Leptogorgia sarmentosa were abundant and frequent in the studied area, while Leptogorgia lusitanica was less abundant. All species evidenced a similar depth pattern, that is abundance significantly increased with depth below 15 m. At shallower waters (up to 15 m), the distribution of gorgonians may be constrained by abiotic factors and competition with algae. Indeed, the abundance of gorgonians was negatively correlated with the percentage cover of algae along the depth gradient, but gorgonians and sponges coexist. Competition among gorgonian species also seems to be low in this area because of the similarity in the abundance pattern observed for the most abundant species and also their high association. In NE Atlantic shallow temperate rocky bottoms, the distribution of gorgonians seems to be influenced by environmental factors and biological interactions, namely competition (algae) and coexistence (sponges and other gorgonians).     

Coastal-flood risk management in central Algarve: Vulnerability and flood risk indices (South Portugal)

This paper presents an analysis of the vulnerability (AVI Index) and hazard of flooding by sea level rise (FRI Index) in the central Algarve (South Portugal), between the cities of Portimão and Tavira, which is an area of intense urban impact and fast growing tourism. The vulnerability index was calculated using the following parametric thematic maps: lithology, geomorphology, slopes, elevations, distances, bathymetry, variations of the coastline, wave height and activity, variations of sea level and tidal range. The AVI Index was validated by the results obtained from the analysis of the risk of flooding from the FHI Index applied to several time horizons (X₀-present, X₁-100 years, X₂-500 years, X₃-1000 year, X₄-Storm and X₅-Tsunami). Application of GIS and remote sensing techniques, viz. spatial analysis, interpolation processes and geostatistical analysis, permitted a regional forecasting model of change in the mean sea level and the ensuing consequences to be established. Analysis of the obtained results shows an increase in potential flood zones in populous coastal tourist areas with a high risk of exposure and a significant spatial extent of 8.84 km² only in Faro municipality. The assessment and delineation of other endangered sectors could contribute to designing appropriate long- term management policies for the coastal of Central Algarve.     

Coscinodon monchiquensis R.D.Porley,Ochyra & Ignatova (Grimmiaceae), a new species from the Algarve,southern Portugal

Coscinodon monchiquensis is described as a new species from the Serra de Monchique in the western part of the Algarve region in southern Portugal. It differs from the widespread C. cribrosus in having only slightly plicate leaves (in the latter species the leaves are usually strongly plicate to the base), a weakly recurved leaf margin in the proximal ? and very fragile and markedly fenestrate peristome teeth which fall away after dehiscence giving the mature capsules a gymnostomous appearance. In cases where C. cribrosus has only weak plications to mid-leaf, the plane leaf margin at once separates it from C. monchiquensis. The affinities of C. monchiquensis are discussed, and molecular phylogenetic analysis of the nrITS region indicates its sister position to all other congeners. A key to the determination of European members of Coscinodon and similar taxa is given.     

Behaviour of fish by-catch in the mouth of a crustacean trawl

The behaviour of fish by-catch was recorded and characterized by in situ observations in the mouth of a crustacean trawl using an underwater camera system with artificial light, at depths between 106 and 461 m, along the central coast of Chile. The groups or species studied were rattails (family Macrouridae), Chilean hake Merluccius gayi gayi, sharks (orders Carcharhiniformes and Squaliformes), skates (family Rajidae), flatfishes (genus Hippoglossina) and small benthopelagic and demersal fishes (orders Osmeriformes, Stomiiformes, Gadiformes, Ophidiiformes and Perciformes). The fish behaviour was categorized in terms of (1) position in the water column, (2) initial orientation with respect to the trawl, (3) locomotion and (4) swimming speed with respect to the trawl. Rattails, sharks, skates and flatfishes were passive in response to the trawl and showed similar behavioural patterns, with most fishes observed sitting or touching the bottom with no swimming or other activity. Merluccius gayi gayi was the most active species, displaying a wide combination of behavioural responses when the trawl approached. This species showed several behavioural patterns, mainly characterized by swimming forward at variable speed. A fraction of small bentho-pelagic and demersal fishes also showed an active behaviour but always at lower speed than the trawl. The species-specific differences in behaviour in the mouth of the trawl suggest that improvements at the level of the footrope can be made to reduce by-catch, especially of passive species.     

Age and growth, mortality, reproduction and relative yield per recruit of the bogue, Boops boops Linné, 1758 (Sparidae), from the Algarve (south of Portugal) longline fishery

Samples of Boops boops ranging from 7.4 to 30.5 cm were obtained mainly by longline, supplemented by beach seining in the Ria Formosa lagoon, and by market sampling in the Algarve (southern Portugal). The macroscopic analyses of the gonads and the gonad somatic index showed that the south coast of Portugal B. boops spawn mainly from late winter to spring, between February and May. The length at first maturity was similar for males and females and the value for both sexes combined was estimated to be 15.22 cm, corresponding to an age range of 1–3. Age was determined by reading growth bands on otoliths. Age determination was validated by marginal increment analysis. The estimated parameters were L_∞ = 28.06, K = 0.22 and t₀ = ?1.42. Mortality rates were calculated for fish captured with longlines, and the estimated parameters were M = 0.33, Z = 1.04 and F = 0.71. Relative yield per recruit analysis and sensitivity analysis showed that the resource is moderately exploited. From the perspective of sustainability, these results provide support for the use of longlines as a gear that is among the least harmful for species such as the bogue.     

Survival of discarded plaice (Pleuronectes platessa) from Norway lobster (Nephrops norvegicus) otter‐trawl fishery

The introduction of landing obligations in the European Union common fisheries policy, has increased the focus on discard survival. Since species with scientifically proven high survival rates may be exempted from the landing obligations, the economic significance for the fishing industry is large. Landing obligations include individuals below the minimum conservation reference size (MCRS), which are not allowed to be sold for human consumption. The Norway lobster (Nephrops norvegicus) fishery is a high value fishery, but with a substantial amount of bycatch of plaice (Pleuronectes platessa) below the MCRS. In the present study, observations were made on the short‐term survival of plaice at or below the MCRS, discarded from a small otter board trawler targeting Nephrops in Skagerrak (ICES 3a). The average short‐term survival of plaice was 15% at haul level, ranging from 0% to 39%, after 10 days of captive observation. Survival significantly decreased with time on deck and the retention of debris in the codend (p < 0.0001), while survival was not correlated to size. Vitality assessments, using a combined reflex impairment and injury score, were tested as predictor of survival and were significantly associated to survival (p < 0.0001) both for individual fish and when grouped by hauls. Seabird predation behaviour was assessed and it was estimated that seabirds predated or pursued 85% of discarded plaice below the MCRS.