Spawning cycles and habitats for ballyhoo (Hemiramphus brasiliensis) and balao (H. balao) in south Florida

Two halfbeak species, ballyhoo (Hemiramphus brasiliensis) and balao (H. balao), are harvested as bait in south Florida waters, and recent changes in fishing effort and regulations prompted this investigation of the overlap of halfbeak fishing grounds and spawning grounds. Halfbeaks were sampled aboard commercial fishing vessels, and during fishery-independent trips, to determine spatial and temporal spawning patterns of both species. Cyclic patterns of gonadosomatic indices (GSIs) indicated that both species spawned during spring and summer months. Histological analysis demonstrated that specific stages of oocyte development can be predicted from GSI values; for example, female ballyhoo with GSIs >6.0 had hydrated oocytes that were 2.0−3.5 mm diameter. Diel changes in oocyte diameters and histological criteria demonstrated that final oocyte maturation occurred over a 30- to 36-hour period and that ballyhoo spawned at dusk. Hydration of oocytes began in the morning, and ovulation occurred at sunset of that same day; therefore females with hydrated oocytes were ready to spawn within hours. We compared maps of all locations where fish were collected to maps of locations where spawning females (i.e. females with GSIs >6.0) were collected to determine the degree of overlap of halfbeak fishing and spawning grounds. We also used geographic information system (GIS) data to describe the depth and bottom type of halfbeak spawning grounds. Ballyhoo spawned all along the coral reef tract of the Atlantic Ocean, inshore of the reef tract, and in association with bank habitats within Florida Bay. In the Atlantic Ocean, balao spawned along the reef tract and in deeper, more offshore waters than did ballyhoo; balao were not found inshore of the coral reef tract or in Florida Bay. Both halfbeak species, considered together, spawned throughout the fishing grounds of south Florida.

Horizontal and vertical movements of juvenile bluefin tuna (Thunnus thynnus) in relation to oceanographic conditions of the western North Atlantic, determined with ultrasonic telemetry

We employed ultrasonic transmitters to follow (for up to 48 h) the horizontal and vertical movements of five juvenile (6.8–18.7 kg estimated body mass) bluefin tuna (Thunnus thynnus) in the western North Atlantic (off the eastern shore of Virginia). Our objective was to document the fishes’ behavior and distribution in relation to oceanographic conditions and thus begin to address issues that currently limit population assessments based on aerial surveys. Estimation of the trends in adult and juvenile Atlantic bluefin tuna abundance by aerial surveys, and other fishery-independent measures, is considered a priority. Juvenile bluefin tuna spent the majority of their time over the continental shelf in relatively shallow water (generally less then 40 m deep). Fish used the entire water column in spite of relatively steep vertical thermal gradients (≈24°C at the surface and ≈12°C at 40 m depth), but spent the majority of their time (≈90%) above 15 m and in water warmer then 20°C. Mean swimming speeds ranged from 2.8 to 3.3 knots, and total distance covered from 152 to 289 km (82–156 nmi). Because fish generally remained within relatively con-fined areas, net displacement was only 7.7–52.7 km (4.1–28.4 nmi). Horizontal movements were not correlated with sea surface temperature. We propose that it is unlikely that juvenile bluefin tuna in this area can detect minor horizontal temperature gradients (generally less then 0.5°C/km) because of the steep vertical temperature gradients (up to ≈0.6°C/m) they experience during their regular vertical movements. In contrast, water clarity did appear to influence behavior because the fish remained in the intermediate water mass between the turbid and phytoplankton-rich plume exiting Chesapeake Bay (and similar coastal waters) and the clear oligotrophic water east of the continental shelf.

Physicochemical and biological cycles in a tide dominated, nitrogen-polluted temperate estuary

Spatio-temporal variations in the physicochemical and biological parameters in the Morlaix estuary on the Brittany coast of France were studied. Hydrographically, the estuary can be classified into 3 segments: the upper estuary where stratification always persists, the lower estuary where vertical homogeneity is permanent, and a middle estuary where there is a regular oscillation of stratification and homogeneity during every tidal cycle, stratification being associated with slack waters and homogeneity, with ebb and flood. Nitrogen pollution in the estuary is very intense.

Bothid larvae (Pleuronectiformes-pisces) of the Gulf od Thailand and South China Sea

The larvae of bothids were found to be sparsely distributed in the Gulf of Thailand and South China Sea being only 11.9% in the Naga Expedition Collections. They were confined mostly to the coastal waters and were found in near shore stations situated between Bangkok and Saigon. Their density was high in the Gulf of Thailand. The larvae seem to prefer darkness with greater incidence during April 16 to October 15 period, with a peak in the collections taken during April. This report includes the occurrence of 17 species belonging to 6 genera collected from the Gulf of Thailand and South China Sea, along with their regional, seasonal as well as diurnal variations

Distribution, biology and behaviour of the giant trevally, Caranx ignobilis- a candidate species for mariculture

Fishery and biology of the giant trevally, Caranx ignobilis exploited along the Tuticorin coast of Tamilnadu were monitored during 2001-2006. Fishery occurred round the year with peak landings during April-August. Spawning and recruitment occur almost round the year with peak during November-December. Young ones are abundant in shallow coastal waters and as grows, they move to deeper waters. Growth parameters, L"' and K are estimated respectively as 143.6 cm and 0.69/year and 'to' as -0.0242 year. Estimates show that they grow fast and attain 73, 108, 126 and 134 cm in total length by first, second, third and fourth year respectively. Their weight increment is also fast and attains 5.5 kg, 16.8 kg, 25.9 kg and 33.7 kg respectively during the period. Stock assessment indicated that the stock at present is over exploited and under heavy fishing pressure. Rearing trial in aquarium tank showed that they are compatible to confined rearing conditions. Based on the distribution and biology of the species, their mariculture potential is discussed.

Fish sauce from two species of unexploited deep sea fish Peristedion adeni and Peristedion weberi

Two species of unexploited deep sea fish Peristedion adeni and Peristedion weberi caught from the Exclusive Economic Zone of India were subjected to fermentation at ambient temperature (30 ± 2°C) in the presence of salt in 4:1 ratio. Periodical analysis of the fermented product was carried out up to one year. The sauces had brownish yellow colour and conformed to special grade of the standards prescribed by the Food and Drug Administration. Further solubilization of protein after 9 month's maturation was not appreciable.

Lakes Wamala and Kijanebalola: evaluation of the fisheries resources during July 1975

This report presents the results of the second (in 1975) fisheries resource survey for Lake Wamala conducted from 10th to 16th July 1975. The first similar survey covered the period 14th to 20th May 1975. The areas sampled consisted of the river-month areas, the papyrus-fringed inshore waters and the open dee offshore waters. In an effort to find the possible major causes of the decline in catch and seasonal disappearance of fish-hence a solution to the problem(s)-a second fisheries resource survey using multifilament nylon gillnets was conducted on Lake Kijanebalola during the period 17th to 21st July 1975. The first survey was similar and covered the period 21st to 27th May 1975.

ALGAL GROWTH POTENTIAL AND NUTRIENT LIMITATION IN SPRING IN THREE-GORGES RESERVOIR, CHINA

In China, especially in Three-Gorges Reservoir, our knowledge of the algal growth potential and nutrient limitation was still limited. In the spring of 2006, the water column ratios of total nitrogen/total phosphorus were investigated and algal bioassays performed to determine algal growth potential of waters and nutrient limitation of mainstream and Xiangxi Bay of Three-Gorges Reservoir. The results showed sampling sites in mainstream were co-limited by N and P or P-limited alone, and sites in Xiangxi Bay were N-limited alone. Fe likely played an important role in determining the appearance and disappearance of algal blooms of Three-Gorges Reservoir. Native algae, Pseudokirchneriella subcapitata and Cyclotella meneghiniana, had high growth potential in Three-Gorges Reservoir.

Influence of Potamogeton crispus growth on nutrients in the sediment and water of Lake Tangxunhu

An incubation experiment was performed on Potamogeton crispus (P. crispus) using sediment collected from Lake Tangxunhu in the center of China, in order to determine the effects of plant growth on Fe, Si, Cu, Zn, Mn, Mg, P, and Ca concentrations in the sediments and overlying waters. After 3 months of incubation, Ca, Mg, and Si concentrations in the water column were significantly lower, and P and Cu concentrations were significantly higher than in unplanted controls. The effect of P. crispus growth on sediment pore waters and water-extractable elements varied. Concentrations of Ca, Mg, Si, Fe, Cu, and Zn were significantly higher, and P was significantly lower, than in pore waters of the control. Water-extracted concentrations of Fe, Mg, and Si in the sediments were lower, and P was higher, than in the control. Presence of P. crispus generally enhanced concentration gradients of elements between pore waters and overlying waters but not for P. The growth of P. crispus was associated with an increase in water pH and formation of root plaques, resulting in complex effects on the sediment nutritional status.

Allelopathic interactions between Potamogelon maackianus and Microcystis aeruginosa

The allelopathic interactions between Potamogeton maackianus and toxic cyanobacteria (Microcystis aeruginosa) were studied. P maackianus inhibited the growth of M. aeruginosa, both in a coexistence culture system and in exudates experimental culture system. M. aeruginosa also showed effects on the secondary metabolic biosynthesis and secreting behavior of P maackianus. The main lipophilic components of the hexane extracts and the exudates from the macrophyte were analyzed through GC-MS determination. The lipophilic components of the hexane extracts and the exudates from P. maackianus were influenced by M. aeruginosa or their released chemicals. Comparing the lipophilic constituents of the hexane extracts with those in the exudates, the results showed that weak polar compounds contained in the macrophytes can be secreted into the surrounding water. Many compounds, such as N-phenyl-2-naphthalenamine and isopropyl myristate, were detected both in the hexane extracts and the exudates. The changes of lipophilic components in the hexane extracts would be a response to the stress of toxic cyanobacteria or their released toxins. Those changes of exudates, especially the increased content of N-phenyl-2-naphthalenamine, might also be an induced defensive behavior mediated by the released toxins from M aeruginosa. The study results about reciprocal allelopathic responses between macrophytes and cyanobacteria can help in the management of eutrophic waters, and is also important information concerning strategies for recovering eutrophic waters.

Discharges and sediments as sources of extracellular alkaline phosphatase in a shallow Chinese eutrophic lake

Total alkaline phosphatase activity (APA) and soluble reactive phosphorus (SRP) concentrations were measured in municipal wastewater, and a shallow Chinese freshwater lake receiving it. Activities of Dissolved alkaline phosphatase ( ADAP) in overlying and interstitial water were also analyzed monthly at three sites for several years. The lake was enriched with SRP and alkaline phosphatase by discharge of the wastewater, indicating that the inclusion of APA for estimating water pollution was reasonable. Annual data showed that APA in coarser fraction was significantly higher at the site receiving more wastewaters, both in surface and overlying water, suggesting that resuspension of enzyme most likely occurred in the basin heavily discharged. ADAP was an order of magnitude higher in the wastewater than those in lake waters, and was generally higher in interstitial water, a feature more striking at the site receiving more discharges. Besides, it was irrespectively inhibited by Na2WO4, L-cysteine and EDTA-Na, but stimulated by Cu2+, Zn2+, CTAB and Triton X-100 in interstitial, overlying and surface waters. This similarity of responding patterns to the stressors indicated an analogy between dissolved alkaline phosphatase in water column and that in interstitial water, supporting the hypothesis that the polluted sediments act as source of dissolved alkaline phosphatase in eutrophic lakes.

Surface pigments,algal biomass profiles,and potential production of the euphotic layer:Relationships reinvestigated in view of remote-sensing applications

Maps of surface chlorophyllous pigment (Chl a + Pheo a) are currently produced from ocean color sensors. Transforming such maps into maps of primary production can be reliably done only by using light-production models in conjuction with additional information about the column-integrated pigment content and its vertical distribution. As a preliminary effort in this direction. $\ticksim 4,000$ vertical profiles pigment (Chl a + Pheo a) determined only in oceanic Case 1 waters have been statistically analyzed. They were scaled according to dimensionless depths (actual depth divided by the depth of the euphotic layer, $Z_e$) and expressed as dimensionless concentrations (actual concentration divided by the mean concentration within the euphotic layer). The depth $Z_e$ generally unknown, was computed with a previously develop bio-optical model. Highly sifnificant relationships were found allowing $\langle C \rangle_tot$, the pigment content of the euphotic layer, to be inferred from the surface concentration, $\bar C_pd$, observed within the layer of one penetration depth. According to their $\bar C_pd$ values (ranging from $0.01 to > 10 mg m^-3$), we categorized the profiles into seven trophic situations and computed a mean vertical profile for each. Between a quasi-uniform profile in eutrophic waters and a profile with a strong deep maximum in oligotrophic waters, the shape evolves rather regularly. The wellmixed cold waters, essentially in the Antarctic zone, have been separately examined. On average, their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values of $ρ$, the ratio of Chl a tp (Chl a + Pheo a), have also been obtained for each trophic category. The energy stored by photosynthesizing algae, once normalized with respect to the integrated chlorophyll biomass $\langle C \rangle _tot $ is proportional to the available photosythetic energy at the surface via a parameter $ψ∗$ which is the cross-section for photosynthesis per unit of areal chlorophyll. By tanking advantage of the relative stability of $ψ∗.$ we can compute primary production from ocean color data acquired from space. For such a computation, inputs are the irradiance field at the ocean surface, the "surface" pigment from which $\langle C \rangle _tot$ can be derived, the mean $ρ value pertinent to the trophic situation as depicted by the $\bar C_pd or $\langle C \rangle _tot$ values, and the cross-section $ψ∗$. Instead of a contant $ψ∗.$ value, the mean profiles can be used; they allow the climatological field of the $ψ∗.$ parameter to be adjusted through the parallel use of a spectral light-production model.

Developing Porphyra/salmon integrated aquaculture for bioremediation and diversification of the aquaculture industry

FUNCTIONAL-FORM GROUPS; RED ALGAE; ATLANTIC SALMON; NEW-HAMPSHIRE; NITROGEN; PHOSPHORUS; RHODOPHYTA; TEMPERATURE; NUTRIENTS; KJELLMAN

Diversity and spatial distribution of sediment ammonia-oxidizing crenarchaeota in response to estuarine and environmental gradients in the Changjiang Estuary and East China Sea

Ammonia-oxidizing archaea (AOA) have recently been found to be potentially important in nitrogen cycling in a variety of environments, such as terrestrial soils, wastewater treatment reactors, marine waters and sediments, and especially in estuaries, where high input of anthropogenic nitrogen is often experienced. The sedimentary AOA diversity, community structure and spatial distribution in the Changjiang Estuary and the adjacent East China Sea were studied. Multivariate statistical analysis indicated that the archaeal amoA genotype communities could be clustered according to sampling transects, and the station located in an estuarine mixing zone harboured a distinct AOA community. The distribution of AOA communities correlated significantly with the gradients of surface-water salinity and sediment sorting coefficient. The spatial distribution of putative soil-related AOA in certain sampling stations indicated a strong impact of the Changjiang freshwater discharge on the marine benthic microbial ecosystem. Besides freshwater, nutrients, organic matter and suspended particles, the Changjiang Diluted Water might also contribute to the transport of terrestrial archaea into the seawater and sediments along its flow path.

The variation of upper ocean structure and paleoproductivity in the Kuroshio source region during the last 200 kyr

A core from the source region of the Kuroshio warm current (east of the Luzon Island) was analyzed using several proxies in order to study the variability of the Western Pacific Warm Pool (WPWP) during the last two glacial-interglacial cycles. Primary productivity (PP) variations were deduced from variations in the coccolith flora. Primary productivity was higher during glacial periods (the end of Marine Isotope Stage [MIS] 3, some periods in MIS 2 and 6), and decreased during interglacial periods (MIS 7, MIS Se and probably MIS 5c-5d), with the lowest PP in MIS 5e. variations in the delta C-13 difference in benthic and bulk carbonate, thus in the vertical gradient of delta C-13 in dissolved inorganic carbon (Delta delta C-13(c). (wuellerstorfi-N. dutertrei) and Delta delta C-13(c.) (wuellerstorfi-coccolith)) Coincided With the PP Changes, showing that export productivity was low during interglacial periods (MIS 7, MIS 5e and Holocene) and high during glacial periods (MIS 6, probably MIS 5c-5d, late MIS 4 and late MIS 3). Comparison of foraminiferal carbonate dissolution indicators and PP changes reveals that nannofossil assemblage in core Ph05-5 is not sensitive to carbonate dissolution intensity. The depth of the thermocline (DOT) was estimated from planktonic forminiferal assemblages, and was relatively greater during interglacial periods (MIS 7, MIS 5e, probably MIS 5c and Holocene) than during glacials (middle MIS 6, probably MIS 5b and 5d, some periods in MIS 4, MIS 3 and MIS 2). Good coherence between the paleoproductivity records and the DOT suggests that the DOT changes could be the primary control factor in changes of paleoproductivity, and the glacial high productivity in the Kuroshio source region could be associated with a global increase of nutrient concentration in the intermediate waters that upwelled into the photic zone. The low CO2 values derived for intervals of high productivity and a relatively shallow DOT suggest that the changes in biological productivity and DOT in the equatorial Pacific could have modified atmospheric CO2 concentrations. High Sea Surface Temperatures (SSTs) during the warm MIS 5e in combination with intensified monsoonal rain fall could have resulted in a more intense stratification of the upper waters, resulting in low nutrient supply to the surface waters and a resulting decrease in productivity. (C) 2010 Elsevier B.V. All rights reserved.