Community Structure of Fishes and Habitat Complexity on a Tropical Rocky Shore

The relationship between the variables of reef fish community structure (fish richness, fish diversity and total number of fishes) and those of habitat complexity (total surface area, substratum diversity, topographic complexity, number of holes, percent cover of turf algae, zoanthids, millepores, massive corals, bare rock, encrusting calcareous algae, urchins, other sessile organisms and Sargassum) were examined on three different rocky shores (FA, FB and FT) at Arraial do Cabo, a tropical region located on Brazilian southeastern coast (23° S, 42° W). Fish abundance and vertical distribution were assessed by a visual census technique using strip transects. Percentage cover of benthic organisms and other substratum types were calculated by replicated transects using a chain laid down on the substratum. Topographic complexity was determined by the chain link method and number of holes were estimated by direct counts on replicated transects. More than 91 fishes belonging to 37 families were seen in all study sites during one year of visual census effort. FA and FB sites had similar fish community structure and habitat complexity characteristics, while FT showed different habitat characteristics and higher fish diversity and richness, plus total number of fishes. Vertical distribution of fishes along the rocky shores studied seemed to be predictable and was determined by factors such as feeding habits and behavior, availability of refuges and social interactions. The habitat variables that best explained the higher diversity and number of fishes observed in FT site were total surface area of rocky shores and the abundance of benthic sessile invertebrates; these conditions were typical of rocky shores more exposed to wave surge.     

Assessment of Fluoride in Three Selected Polluted Environments along the Egyptian Mediterranean Sea: Effects on Local Populations

Fluoride ion (F^?) is a relevant component of concern due to its potential toxicity for humankind. This study clarifies the status of F^? for human health in three polluted regions along the Egyptian Mediterranean Sea coast, and determining its contents in seawater and different fish tissues (muscle, skin, brain, and bone). Fluoride ion concentrations in different fish tissues had a descending trend of brain > skin > muscle > bone with averages of 26.8 ± 26.0, 24.8 ± 6.5, 12.7 ± 2.3, and 9.0 ± 1.6 μg F^?/g wet wt, respectively. The bioconcentration factor for fluoride ion in different fish tissues was determined and multivariate analyses were conducted. The human health hazard assessment from fish consumption and seawater contact using hazard quotient (HQ) and ingestion and dermal absorption dose of whole body for different ages of females and males as well as the specified body parts (legs, arms, and hands) were calculated. Although the calculated daily intake values for ingestion of fish in the present study were lower than some established tolerable daily intake values, their hazard quotients were within 1 ≥ HQ < 10 and may reflect a possible fluoride adverse effect on human health from the consumption of the gathered fish species.     

How Many Seed Transfer Zones Are Necessary for the Preservation of the Genetic Identity of Austrocedrus chilensis Natural Populations in Argentina?

Two different studies based on isozymes that include genetic structure analysis have arrived at contrasting conclusions regarding the minimum number of seed transfer zones for Patagonian cypress (Austrocedrus chilensis) in Argentina that are required in order to avoid genetic contamination in restoration programs. Unfortunately, the more recent article lacks discussion on these controversial results, which is, therefore, the purpose of this article. The reliability of the markers used and the sampling performed in these studies are evaluated comparatively. The later study found higher levels of diversity and differentiation but paradoxically suggested that only two seed transfer zones would be enough to preserve the genetic identity of the natural populations of the species, whereas the earlier study concluded that at least five are necessary. Arguments are presented here for the case that definition of fewer than five genetically homogeneous groups is absolutely inappropriate and implies a probable risk of genetic contamination and maladaptation.     

Origin and potential ecological risk assessment of trace elements in the watershed topsoil and coastal sediment of the Oualidia lagoon,Morocco

The Oualidia lagoon provides important ecosystem services, such as fishing, aquaculture, tourism and high biological and ecological productivity. Many indices have been developed to evaluate environmental risks and to estimate the anthropogenic contribution of potentially toxic elements (PTE) in surficial sediments. The results show that the concentrations of the PTE found in surface sediments due to the anthropogenic activities in the area (urban effluents, aquaculture and agricultural areas) are significantly higher than those from the local background and sediment quality guidelines (SQGs). The potential ecological and biological risk index present satisfactory results. However, the sites near to the areas where anthropogenic activities are developed present 49% probability of toxicity, while the rest of the lagoon, present 9% to 21% probability of toxicity and low potential ecological risk, except for Hg where the risk was considered to be considerable. The PTE are mainly originated from the anthropogenic activities; nevertheless, anthropogenic contributions represent up to 69% of the total sediment of content, but it depends on the PTE: Cd (16%), Ni (38%), Zn (41%), Cr (43%), Cu (56%), Hg (68%), Pb (69%). Compared with the Sub-basin soils, the PTE are higher than 80%, hence the sub-basin feeds the lagoon by these elements (PTE).     

ANNUAL PRODUCTIVITY AND EXTRACELLULAR RELEASE OF DISSOLVED ORGANIC COMPOUNDS BY THE EPIBENTHIC ALGAL COMMUNITY OF A BRACKISH MARSH1

Annual productivity and excretion of organic compounds by epibenthic algae in a coastal Texas marsh were investigated using ¹⁴C techniques. Over the course of two years, productivity and extracellular release were measured bimonthly to assess the environmental factors affecting seasonal patterns. Annual productivity was estimated to be 71 gc·m^?2, approximately 10% of the estimated net aerial productivity of the grass canopy in this area. The percentage of photoassimilated carbon released was fairly constant, and the rate of excretion appeared to be primarily dependent upon the rate of carbon fixation. Greater rates of release were observed with high salinity, low soil moisture conditions. It was estimated that up to 10% of the DOC in adjacent tidal creek water could be produced by this community and could represent an important source of nutrients for consumers in the system.     

DISTRIBUTION,SEASONALITY AND REPRODUCTIVE PHENOLOGY OF BANGIA ATROPURPUREA (RHODOPHYTA) IN RHODE ISLAND,U.S.A.1

Forty-seven sites along the Rhode Island coastline were sampled on a seasonal basis for the presence of the red alga Bangia atropurpurea (Roth) C. Ag. This species was found to be widely distributed, occurring at 94% of the hard, stable substrates sampled. Bangia populations were most, widespread in the winter (71% of sites) and least frequent in the summer (29% of sites). At one location, three high intertidal populations (average height 101 cm) and three low intertidal populations (average height 14 cm) were sampled monthly for two years. The upper intertidal populations appeared in September and persisted until at least May, whereas the lower populations were ephemeral, appearing for only a few months in late winter. The high intertidal populations were present on 85% of the sampling dates white the lower ones were observed on 25% of the sampling dates. Upper intertidal filaments reproduced exclusively by asexual monospores unlike those of the lower populations which were largely sexual. The maximum diameter of asexual and carpogonial filaments was 120 and 250 nm, respectively. Monosporagenesis was strongly correlated to temperature whereas gametogenesis was strongly correlated to photopriod.     

Nematode Community Structure along the Continental Slope off the Kenyan Coast,Western Indian Ocean

Metazoan meiofauna and in particular nematode densities, diversity, community structure were studied in relation to water depth (20 m, 50 m, 500 m, 1000 m and 2000 m) along four bathymetric transects in the Western Indian Ocean off the Kenyan coast. Nematode densities ranged between 276–944 ind./10 cm², which is comparable to values from other oligotrophic areas in the world. Densities was correlated with oxygen concentrations in the overlying water, since they were lowest at mid‐depth (500–1000 m) coinciding with the minimum oxygen level. Nematode community structure (at genus level) resembles communities found in temperate slope regions, which are also characterized by a low productivity. The community structure showed correlations with sediment composition, water depth and oxygen levels in the overlying water. Sediment composition was mainly important at the shelf where nematodes separated into a silty sediment‐dwelling community with high abundances of Daptonema, Dorylaimopsis, Terschellingia and Halalaimus, and a sandy sediment‐dwelling community characterised by high abundances of Microlaimus and Halalaimus. The genera Monhystera, Acantholaimus, Sabatieria, Molgolaimus and Halalaimus dominated the slope communities. The characteristic deep‐sea taxa, the monhysterids and Acantholaimus increased in relative abundance with increasing depth, to become dominant at the lower slope (2000 m). The upper (500 m) and mid‐slope (1000 m), which coincided with the lowest oxygen concentrations, were colonised by Sabatieria, a genus that is known to inhabit suboxic sediments. Diversity at the level of the genera showed an unimodal trend along the sampled gradient, with highest values at mid‐depth (500 m). Although the oxygen minimum at mid depths is much less pronounced than in adjacent areas, the results of this study suggest an impact on the present communities.     

Records of ocean sunfish Mola mola along the Norwegian coast spanning two centuries, 1801–2015

Records of the ocean sunfish Mola mola along the Norwegian coast were compiled from all possible sources: literature, media, databases and museums. A total of 216 records were found between 1801 and 2015. They were distributed along the whole coast, except for the most north‐eastern part. Nearly all years with more than five records were after 2000, with 1985 as the only exception and with a maximum of 23 records in 2014. Most, 92·4%, were from July to December. Records from before 1979 were more incidental and random and no sunfish were recorded in 54 separate years between 1879 and 2015. The northernmost record was from 70° 44′ N in December 1881. No relationship between year and latitude was found. Forty‐four per cent of the records were of sunfish caught in fishing gear, 27% were found stranded and 30% were observed alive at sea. A trend of a decrease in numbers of observations of living individuals and an increase in numbers of strandings as dead individuals as autumn progressed was found. Geographical differences in the three categories of observation were also found. Among the specimens whose size was recorded, most were small, <30 kg and 70 cm in total length. Only 10 were heavier than 100 kg, all these were from before 1960. Annual numbers correlated weakly with sea temperatures. This was supported by a weak negative correlation with the North Atlantic Oscillation (NAO) index, because the majority of years since 2000 had a negative NAO.     

台湾海峡离岛工业区海域浮游生物丰度之长期变化

本研究利用1993-2010年在云林县台西乡沿岸的8个站位所进行的一年四季近岸10 m及离岸20 m水深的浮游生物调查资料及同步的水质资料, 分析了发电厂建成后对浮游生物的影响。本海域18年内浮游生物各类群丰度/密度的各季节平均值, 皆以第四季(10-12月)为最低, 而各个类群的最高平均值出现的季别并不一致。其中浮游动物出现于第一和第二季(1-6月), 浮游植物和虾、蟹幼体在第二季(4-6月), 而鱼卵和仔鱼则是在第一至第三季(1-9月)。自2000年第三季起, 测线5的测站经常有pH值低于7.8的情形。当该海域水体测得pH值低于7.8时, 浮游动物(75±69 ind./m³)﹑浮游植物((1.60±2.28)×10³ cell/L)﹑虾幼体(2.4±5.8 ind./m³)﹑蟹幼体(1.9±5.0 ind./m³)及鱼卵(0.88±1.10 ind./m³)和仔鱼(0.16±0.32 ind./m³)的丰度/密度值皆偏低, 仅为历年总平均值的1/2。据此建议将发电厂排入海洋之水体pH值控制在7.8以上, 以降低对浮游生物多样性及丰度的冲击。     

Attraction of ambrosia and bark beetles to coast live oaks infected by Phytophthora ramorum

1 Sudden oak death is caused by the apparently introduced oomycete, Phytophthora ramorum. We investigated the role of bark and ambrosia beetles in disease progression in coast live oaks Quercus agrifolia. 2 In two Marin County, California sites, 80 trees were inoculated in July 2002 with P. ramorum and 40 were wounded without inoculation. Half of the trees in each group were sprayed with the insecticide permethrin [cyclopropanecarboxylic acid, 3‐(2,2‐dichloroethenyl)‐2,2‐dimethyl‐(3‐phenoxyphenyl) methyl ester] to prevent ambrosia and bark beetle attacks, and then were sprayed twice per year thereafter. After each treatment, sticky traps were placed on only the permethrin‐treated trees. Beetles were collected periodically in 2003. 3 Inoculated trees accounted for 95% of all beetles trapped. The ambrosia beetles Monarthrum scutellare and Xyleborinus saxeseni and the western oak bark beetle Pseudopityophthorus pubipennis were the most abundant of the seven species trapped. 4 Permethrin treatment delayed initiation of beetle attacks and significantly reduced the mean number of attacks per tree. Beetles did not attack any wounded or noncankered inoculated trees. 5 Trees with larger cankers trapped more beetles early in the disease. Once permethrin lost effectiveness, the number of beetle entrance tunnels was a more reliable predictor of subsequent trap catch than was canker size. 6 Beetles were initially attracted to P. ramorum cankers in response to kairomones generated in the host‐pathogen interaction. After beetles attacked the permethrin‐treated trees, aggregation pheromones most probably were the principal factor in beetle colonization behaviour.