Stream degradation,fish abundance and the potential viability of ornamental fisheries in south-western Cameroon

Fifteen sites on nine second- and third-order streams in the Mount Cameroon area, with varying degrees of human disturbance, were sampled during wet and dry seasons over 21 months in 2003–2005 to estimate their potential for sustainable exploitation of ornamental fishes. In total, 35 species of fish representing 22 genera and 14 families were captured. By biotope, fish populations per 20 m averaged 528 ± 318.5 fish (8.0 ± 3.02 species) in runs, 86 ± 60.9 fish (2.4 ± 1.06 species) in riffles and 819 ± 480.0 fish (7.8 ± 3.15 species) in pools. Riffles contained significantly fewer individuals and species than either runs or pools. Shannon's index was similar for runs and pools, averaging 1.646 ± 0.429 and 1.548 ± 0.345, respectively, but differed significantly for riffles, averaging 0.652 ± 0.473. There were no significant differences in number of individual fish, number of species or Shannon's index among stream order or season, reflecting the stability of these ecosystems throughout the year. Regression of number of fish per 20 linear m of stream, number of species and Shannon's index against a subjective scale related to stream degradation was significant. In particular, the polluted Limbe River sites had significantly fewer individual fish, fewer species and a lower Shannon index across all biotopes than other sites. Fishing efficiency of local gears was estimated at 27% for easily captured species and 14% for the more difficult ones, and could be used to make relative estimates of fish abundance as a means of monitoring changes in fish abundance. Although species diversity in south-western Cameroon was high, typical of tropical streams globally, total abundance was low, and therefore it is unlikely that a profitable ornamental fish trade could be sustained on the basis of fish captured exclusively from the wild.     

Remarkable Shrimps: Adaptations and Natural History of the Carideans

A histology-based fish health assessment protocol was used in 2009–2010 to assess the health status of Clarias gariepinus from Pongolapoort Dam, South Africa. Nineteen fish were collected by angling. The histology of liver, kidney, gills and testes or ovaries was semi-quantitatively assessed and compared to that of fish from a reference site in the Okavango Panhandle, Botswana. Necropsy observations indicated that C. gariepinus from Pongolapoort Dam were in poorer condition than those from the Okavango Panhandle. Microscopic analysis showed that the mean liver index (I _L), gill index (I _G), testis index (I _T) and ovary index (I _O) were higher, although not statistically significant, in fish from the Okavango Panhandle. The difference in the results between the necropsy-based observations and semi-quantitative histological results was due to the external abnormalities detected in the necropsy analysis, including parasites and skin lesions, not expressing as changes to cell and tissue structure. According to the parameters measured, C. gariepinus from Pongolapoort Dam were in a healthy state.     

我国畜禽细菌类主要兽医病原微生物及其疫苗研制与应用概况

我国畜禽养殖体系庞大,细菌类病原微生物在畜禽间流行传播引发的畜禽疫病频发不仅会造成严重的经济损失,部分病原菌还会引发人兽共患病,威胁公共卫生安全。本文对我国近年来流行的家畜和家禽细菌类病原微生物进行了概述,并梳理了目前我国家畜和家禽疫苗研制和应用情况,以期为我国细菌类畜禽疫病的防控提供理论基础。     

Analysis of the marine ornamental fish trade at Ceará State, northeast Brazil

Brazil is one of the leading exporters of ornamental fishes, mostly freshwater; however, monitoring of the trade is nearly non-existent in the country. This paper provides an initial assessment of a new venture, the marine aquarium fish trade at Ceará State, northeast Brazil, aiming to document the species traded, to provide preliminary estimates of numbers of specimens traded, and to identify priorities in data collection and monitoring. A total of 143 species and 199 304 fishes were traded. From the total, 109 species were native and represented 84% of the fishes traded. Thirty-four exotic species figured on the permits and amounted to nearly 16% of the exports; however, most of them consist of misidentified native species. Nearly 90% of the fish trade was directed to the international market. Official figures represent an underestimation of the total number of captured specimens.     

Comparison of Vibrio spp. populations found in seawater, in exhibition aquaria, in fish intestine and in fish feed

Aims:  Vibrio populations in the seawater supply and the water of seven exhibition aquaria that simulate various Mediterranean and tropical ecosystems were compared. The similarity of Vibrio populations in the intestine of various fish species, feed and water was examined. Resistance to the antibiotics used in fish health management was analysed for the dominant Vibrio isolates.
Methods and Results:  Samples were collected for 1 year from seven exhibition tanks reproducing different ecosystems. The diversity and population similarity among vibrios were determined using a miniaturized biochemical phenotyping method. Similar Vibrio populations were found in the water supply and in the water of the Mediterranean ecosystems. However, different Vibrio populations were found in the water of tanks with tropical ecosystems. Vibrio populations in the water seemed to have a greater effect on the composition of intestinal Vibrio populations than those in feed. No resistance to antibiotics was observed, indicating their appropriate use for health management.
Conclusions:  Water characteristics have a greater impact on the composition of Vibrio populations in aquaria and fish intestinal microbiota than bacteria in feed.
Significance and Impact of the Study:  The microbiological monitoring water could provide valuable information for managing the health of exhibition aquaria.     

Ichthyofaunal assemblages in estuaries: A South African case study

This review places the life-history styles of fishes associated with South African estuaries in a global context and presents a classification system incorporating all the major life-history categories for estuary-associated fish species around the world. In addition, it documents the early life histories of the major fish groups in South African estuaries, with particular emphasis on the differing modes of estuarine utilization by marine, estuarine and freshwater taxa.This review details factors influencing the ichthyofaunal community structure in South African estuaries. The availability of fish for recruitment into an estuary depends primarily upon the distributional range of euryhaline marine and estuarine species, with tropical and temperate taxa showing marked abundance trends. Within a particular biogeographic region, however, estuarine type and prevailing salinity regime have a major influence on the detailed ichthyofaunal structure that develops. There is an increasing preponderance of marine fish taxa when moving from a freshwater-dominated towards a seawater-dominated type of system, and a decline in species diversity between subtropical estuaries in the north-east and cool temperate systems in the south-west. Similar declines in fish species diversity between tropical and temperate estuaries in other parts of the world are highlighted.Fish assemblages in estuaries adjust constantly in response to changing seasons, salinities, turbidities, etc. Despite persistent fluctuations in both the biotic and abiotic environment, the basic ichthyofaunal structure appears to have an underlying stability and to be predictable in terms of the response of individual species to specific conditions. This stability seems to be governed by factors such as the dominance of eurytopic taxa within estuarine assemblages and the robust nature of food webs within these systems. The predictability arises from factors such as the seasonality associated with estuarine spawning cycles and juvenile fish recruitment patterns. These patterns, together with a well-documented resilience to a wide range of physico-chemical and biotic perturbations, appear to be an underlying feature of fish assemblages in estuaries around the world.In contrast to marine fish species, estuary-associated taxa have received little conservation attention. Apart from the designation of protected areas, the main direct means of conserving estuary-associated fish stocks include habitat conservation and controls over fishing methods, effort, efficiency and seasonality. Of these, the conservation of fish habitats, the most important, because healthy aquatic environments invariably support healthy fish populations. The use of estuarine sanctuaries for fish conservation is briefly reviewed, as well as the legislation governing the USA National Estuarine Research Reserve System (NERRS) and the Australian Marine and Estuarine Protected Area (MEPA) system. It is concluded that South Africa requires an expansion of the existing Estuarine Protected Area (EPA) network, as well as the upgrading of selected 'estuarine reserves' where fishing is permitted, into 'estuarine sanctuaries' where no exploitation of biological resources is allowed.     

The ecological integrity of the lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part B: Tributaries of the Olifants River

Monitoring on the Lowveld reaches of the Olifants River, Limpopo River System, and its Steelpoort, Blyde, Klaserie and Selati tributaries was initiated in 2009. Analysis of the 2009–2015 data from four Olifants River sites showed deterioration in the river’s ecological condition between where it enters the Lowveld and where it enters the Kruger National Park, with a slight recovery within the Kruger National Park. Physico-chemical, aquatic macroinvertebrate and fish data collected in 2009–2015 at six sites on the Steelpoort, Blyde, Klaserie and Selati tributaries of the Olifants River corroborated the ecological condition of these tributaries. The Selati was the most polluted and was in a critically modified condition, whereas the Klaserie and Steelpoort were in fair condition and the Blyde was in good condition. The Selati appeared to have a significant negative impact on the water quality, macroinvertebrates and fish of the Olifants River within the Kruger National Park.     

The ecological integrity of the Lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part A: Olifants River main stem

The major rivers of the South African ‘Lowveld’ (low-latitude savanna) suffer numerous impacts from upstream economic activities. Whereas monitoring these rivers is required to detect biodiversity losses, record pollution events and devise mitigation strategies, current monitoring programmes are inadequate. In 2009, the South African Earth Observation Network initiated an intensive long-term research programme on the Lowveld reaches of the Olifants River. Physico-chemical parameters, aquatic macroinvertebrates and fish abundances were recorded at four Lowveld sites in the Olifants River. We review six years of this programme. The results suggest deterioration in the ecological condition of the Olifants River with no discernible improvement through protected areas. Trends could not be detected. The parameters measured, sampling methods and/or sampling frequency might be responsible for the limited trends observed, or alternatively the results simply reflect stable conditions despite on-going pollution. Real time monitoring and an expansion in the parameters monitored would add value to the monitoring programme.     

Aquatic Microbiology with Reference to Tannin Degradation

Tannins in aquatic environment cause harmful effects to aquatic life. They are inhibitory to microbial growth, respiration and metabolism. A few microorganisms degrade tannins and the factors influencing degradation are discussed. The need for coordinated approach is emphasized.Memoir No. 300, from Centre of Advanced study in Botany, University of Madras.     

Cell biology of deep-sea multicellular organisms

Establishing tissue cultures derived from deep-sea multicellular organisms has been extremely difficult because of the serious damage they sustain upon decompression and exposure to the high temperature of surface seawater. We developed a novel pressure-stat aquarium system for the study of living deep-sea multicellular organisms under pressure. Using this system, we have succeeded in maintaining a variety of deep-sea multicellular organisms under pressure and atmospheric conditions after gradual, slow decompression. Furthermore, we successfully cultivated and freeze-stocked pectoral fin cells of the deep-sea eel Simenchelys parasiticus collected at a depth of 1,162 m under atmospheric pressure conditions. This review describes novel capture and maintenance devices for deep-sea organisms and cell culture studies of the organisms under atmospheric and pressure conditions.     

Unmonitored trade in marine ornamental fishes: the case of Indonesia’s Banggai cardinalfish (<Emphasis Type="Italic">Pterapogon kauderni</Emphasis>)

Millions of coral reef fishes are collected each year for sale on the international aquarium market. Several marine ornamental species, including the Banggai cardinalfish, are biologically unsuitable for large-scale exploitation, yet their trade continues largely unmonitored. With little known about the Banggai cardinalfish or its trade, we interviewed trade participants from north and central Sulawesi, Indonesia, to document the organization, scale, and price structure of the species local collection and sale. Interviews revealed a large and growing commerce in Banggai cardinalfish, with at least 118,000 fish per month being sold in the Banggai region during the study period. Given the scale of the trade, the species restricted geographic range, and its natural susceptibility to exploitation, we propose that long-term monitoring is needed to safeguard Banggai cardinalfish populations and to serve as a much-needed example for monitoring and managing other marine ornamental fishes at risk of over-exploitation.

Detection of Deefgea chitinilytica in freshwater ornamental fish

Aim: To identify and characterize six chitinolytic bacterial strains isolated from ornamental fish. Methods and Results: Six different isolates of Deefgea chitinilytica were detected in healthy as well as diseased ornamental fish in Germany over a period of 2 years. Bacterial strains were identified using 16S rRNA partial gene sequencing and further characterized using different biochemical microtest systems and additional standard biochemical tests. Conclusion: We show that commercially available biochemical microtest systems are useful for identification of D. chitinilytica, supplemented by 16S rRNA partial gene sequencing. Furthermore, this study provides new information about the occurrence of D. chitinilytica, as this is the first isolation of D. chitinilytica from animals and first described isolation in Europe. Significance and Impact of the Study: Deefgea chitinilytica may be isolated regularly in fish diagnostic laboratories. Therefore, accurate identification of this bacterial species is important. Involvement of D. chitinilytica in opportunistic infections of aquatic organisms cannot be excluded and has to be further investigated.     

Acquisition of fishes and aquatic invertebrates for zoological collections. Is there a future?

The majority of the freshwater fishes in the ornamental trade now originate from captive‐bred sources, as do a large proportion of the freshwater species exhibited in public aquariums. In contrast, commercial operators who also supply marine specimens to the ornamental trade remove directly from the wild approximately 98% of the marine fishes and invertebrates exhibited in public aquariums. The common perception prevails that captive propagation is inherently a better alternative to obtaining animals from the wild. Although captive propagation has been shown to have many benefits for terrestrial species, there are a number of features unique to marine species that challenge the idea that every species should be bred in captivity. Some of the key issues relating to the development of widespread conservation‐oriented captive propagation programs include: 1) the high taxonomic diversity in marine animals; 2) the resultant variety in their reproductive methods; 3) their ecological, behavioral, physiological, and nutritional needs; and 4) our general lack of knowledge on their husbandry and medical care. There are several characteristics of marine fish and invertebrate populations that make them suitable candidates for sustainable harvest. For instance, marine teleosts are “r‐selected,” meaning that they have an extremely high fecundity, and most marine teleosts have a wide distribution and the ability to disperse over long distances. In locations considered for fish collection, appropriate management techniques should be employed to ensure that fishes and invertebrates are collected with as little impact on the ecosystem as possible. The collection of marine fishes and invertebrates for public aquariums and the hobby trade should be managed like a fishery to ensure long‐term sustainability. The public aquarium community should support marine organism certification initiatives, such as the Marine Aquarium Council (MAC). Marine organism certification will create market incentives that encourage and support quality and sustainable practices by creating consumer demand and confidence for certified organisms, practices, and industry participants. The creation of refuges that supply propagules to harvested areas, the rotation of areas fished, species‐specific size limits and seasons, and standardization of collecting, handling, and transportation techniques should be used to manage these fisheries and harvest areas. Zoo Biol 22:519–527, 2003. © 2003 Wiley‐Liss, Inc.