scholarly journals ’n Vergelyking van die Mollusca-diversiteit in die Mooirivier (Noordwes-Provinsie) soos gevind met opnames wat gemaak is in 1963 en weer 50 jaar later

2015 ◽  
Vol 34 (1) ◽  
Author(s):  
Cornelius T. Wolmarans ◽  
Victor Wepener ◽  
Uané Pretorius ◽  
Johannes H. Erasmus ◽  
Kenné N. De Kock
Keyword(s):  
Environmental Changes ◽  
Anthropogenic Impacts ◽  
Abiotic Factors ◽  
Conservation Status ◽  
Habitat Destruction ◽  
Low Flow ◽  
Current Status ◽  
Adjacent Area ◽  
Freshwater Molluscs ◽  
Mollusc Species

The highest number ofdocumented extinctions of any major taxonomic group is ascribed to the Mollusca. Factorsmainly responsible for this include environmental changes and anthropogenic impacts whichresult in habitat destruction. Furthermore, the conservation status of less than 2% of the moreor less 7000 mollusc species, known worldwide, is still not properly assessed. The aim ofthe study done in 2014 was to assess the current status of the mollusc diversity in the MooiRiver and to compare the results to the study done in 1963. The eight sites selected for thissurvey correspond with sites surveyed during the 1963 study, with surveys conducted duringboth an early and late low-flow period. The pH, electrical conductivity (EC) and temperaturewere also measured at each locality. Of the 15 mollusc species collected in 2014, altogether14 were the same as in the 1963 survey. However, an alien invasive species Physa acuta wasadditionally collected during the current survey, which is probably due to an increase inorganic enrichment. During the 1963 survey Burnupia mooiensis and Pisidium langlyanum werepresent at most of the sites, while Gyraulus connollyi and Ferrissia cawstoni were found at sixof the eight sites during the 2014 survey. Most of the molluscs previously recorded, were stillpresent in 2014. With regard to the abiotic factors, the pH values recorded in 2014 showed amoderate to large decrease as compared to the 1963 survey. This acidification is ascribed tothe development of gold mines in the adjacent area and apparently had little influence on themollusc diversity. The increase in EC measured in 2014 did not have any influence on thediversity of the molluscs, probably due to their wide tolerance for this factor. As expected,the temperature measured in 2014 was markedly higher during the late low-flow period ascompared to the early low-flow period. In conclusion, the differences discussed above revealedno obvious influence on the diversity of the freshwater molluscs over a 50 year period, despiteincreased anthropogenic impacts.

scholarly journals Broad and fine-scale threats on threatened Brazilian freshwater fish: variability across hydrographic regions and taxonomic groups

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Murilo Luiz e Castro Santana ◽  
Fernando Rogério Carvalho ◽  
Fabrício Barreto Teresa
Keyword(s):  
Freshwater Fish ◽  
Habitat Loss ◽  
Fish Species ◽  
Threatened Species ◽  
Environmental Changes ◽  
Anthropogenic Impacts ◽  
Conservation Status ◽  
Fine Scale ◽  
Hydrographic Regions ◽  
Taxonomic Groups

Abstract: Anthropogenic environmental changes are the main cause of species extinction during the Holocene. Species have been exposed to major source of threats, such as habitat loss and fragmentation, pollution, introduced species, and harvesting, many of which are derived from specific anthropogenic activities, such as urbanization, agriculture, and damming (i.e. fine-scale threats). However, the importance of these threats on the species conservation status in a given region depends on the type of impacts they are exposed to and the susceptibility of species to these impacts. In this study, we used a database of threatened Brazilian freshwater fish species to test whether the major source of threats and the specific anthropogenic impacts to species vary across hydrographic regions and taxonomic groups. Our results showed that habitat loss is a ubiquitous major threat jeopardizing the conservation status of the Brazilian fish species. However, different fine-scale threats mediate this process across hydrographic regions and taxonomic groups. The combination of impacts from agriculture, deforestation, and urbanization affects most of the threatened species in the basins of the Northeast, South, and Southeast, including the species of the most threatened order, the Cyprinodontiformes. Damming is the main human activity affecting threatened species of Siluriformes, Characiformes, Gymnotiformes, and Cichliformes, especially in northern basins (Amazon and Tocantins-Araguaia). Therefore, we found that specific fine-scale threats influencing threatened species vary across hydrographic regions and taxonomic groups, probably due to geographic variability in the incidence of human activities and differential niche requirements and vulnerability of species to these activities.

scholarly journals Distribution of Burnupia capensis (Walker, 1912) and Burnupia stenochorias (Melvill & Ponsonby, 1903) (Gastropoda: Ancylidae) in South Africa

2009 ◽  
Vol 28 (3) ◽  
pp. 220-236 ◽  
Author(s):  
Kenné De Kock ◽  
Corrie Wolmarans
Keyword(s):  
South Africa ◽  
South African ◽  
Geographical Distribution ◽  
Conservation Status ◽  
Frequency Of Occurrence ◽  
Widespread Species ◽  
Freshwater Molluscs ◽  
Rivers And Streams ◽  
Mollusc Species ◽  
Collection Sites

The presence of Ancylidae in South Africa was established as early as 1848 but the first comprehensive study on this family was reported in 1923. This author came to the conclusion that extensive work still had to be done before it could be declared that knowledge pertaining to the South African representatives of this family could be considered as satisfactory. Another important contribution on South African Ancylidae was published in 1939. After a detailed morphological and histological study on Burnupia mooiensis three decades later the authors stated that the axonomy of the Ancylidae still remained unsatisfactory, a view that was supported by authors as recently as 2002. The National Freshwater Snail Collection (NFSC) was established in 1956 but he oldest sample of Ancylidae on record dates back to 1954 and at present 14 species of Burnupia are represented in the database of the NFSC. This contribution deals with the geographical distribution and specific characteristics of the habitats of B. capensis and B. stenochorias the two most widespread species of this genus in South Africa. Very little is known of the conservation status of the Ancylidae of this country but some results pertaining to this subject are briefly discussed. Burnupia species are relatively inconspicuous organisms that are usually attached to solid objects on the substratum or aquatic vegetation and need to be specifi cally looked for during surveys. Personnel of government authorities and municipalities who made substantial contributions to the number of samples in the NFSC therefore received special training in sampling echniques during workshops. Identification of the specimens was largely based on shell and radula characteristics and on he location of the site of collection. Only samples of which the sampling sites could be located on the 1:250 000 topo cadastral map series of South Africa were considered for further analysis. Respectively 702 and 435 samples of B. capensis and B. stenochorias met this requirement. The loci (1/16 th square degrees) in which the collection sites of these species were located, were distributed in pre-selected intervals of mean annual air temperature and rainfall, as well as ntervals of mean altitude, to illustrate the frequency of occurrence within specific intervals. A temperature index was calculated for all mollusc species in the database from their frequencies of occurrence within the selected intervals and the results used to rank them in order of their association with low to high climatic temperatures. Chi-square values were calculated to evaluate he significance of the difference between frequencies of occurrence in, on, or at the various options or each parameter investigated and furthermore an effect size value was calculated to determine he contribution of each parameter towards establishing the geographical distribution of this species based on the data in the database. A multivariate analysis in the form of a decision tree was also constructed from the data which enabled the selection and ranking of those variables hat maximally discriminated between the frequency of occurrence of these two species in, on, or at the various options for each parameter as compared to all other mollusc species in the database. The majority of samples of both species were collected in rivers and streams and in habitats described as perennial with slow running and clear water. The presence of associated vegetation and a predominantly stony substratum was mentioned for the majority of sampling sites. The geographical distribution of these two species overlapped to a large extent and they were recorded together in 55 loci. However, the 257 loci from which B. capensis were collected covered a more extensive geographical area than the 108 loci from which B. stenochorias was recorded. Both species were poorly represented in the Limpopo, North West and Northern Cape province, a phenomenon that could probably be attributed to a paucity of perennial habitats and the fact that both species in question have poor abilities to overcome conditions of desiccation prevalent in seasonal habitats. Due to the fact that the majority of samples were collected in rivers and streams and on a stony substratum and also because of their largely sessile mode of existence, it is suggested that the feasibility to exploit these two species as indicators of heavy metal pollution should be investigated. It is a known fact that molluscs can accumulate heavy metals in their soft tissue and can also deposit organic substances in their shells. Large scale surveys for freshwater molluscs was terminated in the 1980’s and most of the collection sites recorded in the NFSC were not revisited since, therefore little is known of the conservation status of the freshwater molluscs of South Africa. A comparison of results of several surveys conducted in the Kruger National Park over a period of nearly four decades revealed a marked decline in the number of positive sites with regard to several mollusc species including representatives of the Ancylidae. The well documented geographical distribution of several species of Burnupia in the database of the NFSC could serve as a base of reference for an investigation of the conservation status of this genus of the Ancylidae in South Africa. The fact that these species are well represented in rivers and streams and on stony substratums could facilitate such an investigation in the sense that surveys could be focused on these types of water body. A comparison of the results of such surveys with the documented geographical distribution of all freshwater molluscs in the database of the NFSC could contribute substantially towards the knowledge currently available on the conservation status and species diversity of our indigenous molluscs.

scholarly journals The current status of freshwater molluscs in the Kruger National Park

Koedoe ◽  
2006 ◽  
Vol 49 (2) ◽  
Author(s):  
C.T. Wolmarans ◽  
K.N. De Kock
Keyword(s):  
Species Diversity ◽  
National Park ◽  
Kruger National Park ◽  
Current Status ◽  
Freshwater Molluscs ◽  
Freshwater Mollusc ◽  
Current Survey ◽  
Mollusc Species ◽  
Flow Through ◽  
Alien Invader

Surveys regarding the freshwater mollusc population of the Kruger National Park commenced before 1966 and was repeated in 1995, 2001 and recently in 2006. During this period the park was exposed to several droughts as well as floods, all of which could have had some influence on the various habitats in the park. Industrial developments and urbanisation near some of the major rivers outside the park, but which flow through the park, could also have a detrimental effect on the species diversity of the freshwater molluscs. The recent survey in 45 habitats included several dams and rivers. The survey was done to determine the current status of the mollusc species diversity. By comparing it with previous surveys, an attempt was made to establish the overall health of freshwater mollusc habitats. From the results it is clear that there was a drastic decrease in the mollusc species diversity in five of the habitats. Although there was a slight change in the species composition in some of the major rivers there was no difference in the number of species collected in these habitats. Tarebia granifera, an alien invader mollusc, was found in several rivers and dams. Gyraulus costulatus, Melanoides victoriae and Eupera ferruginea, which could not be found during the survey of 2001, were collected during the current survey.

The status and conservation of native rodents in Western Australia

2000 ◽  
Vol 27 (4) ◽  
pp. 405 ◽  
Author(s):  
K. D. Morris
Keyword(s):  
Western Australia ◽  
Action Plan ◽  
Conservation Status ◽  
Habitat Destruction ◽  
Current Status ◽  
Shark Bay ◽  
The Status ◽  
Threatened Taxa ◽  
Western Australian ◽  
Iucn Criteria

This paper examines the conservation status of Western Australia’s native rodent fauna using IUCN criteria and compares this with their current status under State and Commonwealth legislation, as well as that recommended in the Rodent Action Plan. Of the 35 native rodent taxa known in Western Australia, four (11%) are currently listed as extinct, and six (17%) as threatened under Western Australian legislation. Nine are listed as threatened under Commonwealth legislation. It is proposed that two, currently unlisted, island sub-species should be regarded as threatened. Some decreases in conservation status are also proposed. Predation by feral cats, habitat destruction and the use of surface shelter structures are suggested as primary factors in the decline of native rodents. Conservation programs are underway for most threatened taxa in Western Australia, including the implementation of recovery plans for the Shark Bay mouse and greater stick-nest rat. The heath rat is the only threatened rodent lacking a conservation program in Western Australia. The work planned or required for rodent conservation is presented and includes survey for the critically endangered central rock-rat, and translocation programs for other threatened taxa. The distribution of most taxa is relatively well known; however, there is a need to commence, or complete, taxonomic assessment of some.

scholarly journals Notes on the threatened lowland forests of Mt Cameroon and their endemics including Drypetes burnleyae sp. nov., with a key to species of Drypetes sect. Stipulares (Putranjivaceae)

Kew Bulletin ◽  
2021 ◽  
Author(s):  
Martin Cheek ◽  
Nouhou Ndam ◽  
Andrew Budden
Keyword(s):  
Conservation Management ◽  
Conservation Status ◽  
Central Africa ◽  
Habitat Destruction ◽  
Coastal Forests ◽  
Key To Species ◽  
International Union ◽  
Species Discovery ◽  
Mount Cameroon ◽  
Lowland Forests

SummaryThis paper reports a further discovery of a new endemic threatened species to science in the context of botanical surveys in the lowland coastal forests of Mount Cameroon in the Cross River-Sanaga interval of west-central Africa. These studies now focus on species discovery and conservation through the Tropical Important Plant Areas programme. New species to science continue to be discovered from Mt Cameroon. Most of these species are rare, highly localised, and threatened by habitat destruction, increasing the justification for improved conservation management of surviving habitat. Drypetes burnleyae is placed in and keyed out in Drypetes sect. Stipulares, a group mostly confined to Lower Guinea, here adjusted to accommodate nine species. The conservation status of Drypetes burnleyae is assessed as Endangered (EN B1+2ab(iii)) according to the 2012 criteria of the International Union for the Conservation of Nature. An updated overview of the plant endemics of Mt Cameroon is presented.

scholarly journals A re-evaluation of the occurrence of freshwater molluscs in the Kruger National Park

Koedoe ◽  
1998 ◽  
Vol 41 (1) ◽  
Author(s):  
K.N. De Kock ◽  
C.T. Wolmarans
Keyword(s):  
Species Diversity ◽  
National Park ◽  
Kruger National Park ◽  
Intermediate Hosts ◽  
Freshwater Molluscs ◽  
Freshwater Mollusc ◽  
Mollusc Species ◽  
Trematode Parasites

Most of the previous records of the freshwater molluscs from the Kruger National Park date back prior to and up to 1966. On account of several droughts between 1966 and 1995 it was decided to do a survey of the freshwater mollusc population in 1995 to evaluate the effect of these droughts. The traditional mollusc intermediate hosts were also screened for trematode parasites to establish whether or not they were infected. No infected molluscs were found. Eight of the 19 species reported up to 1966 were not found during the 1995 survey. Three new mollusc species were collected in 1995. The consequences of the drought are clearly visible when the species diversity found in the dams in the 1995 survey, is compared to what was previously recorded.

scholarly journals Conservation Status of Marine Biodiversity in Oceania: An Analysis of Marine Species on the IUCN Red List of Threatened Species

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Beth A. Polidoro ◽  
Cristiane T. Elfes ◽  
Jonnell C. Sanciangco ◽  
Helen Pippard ◽  
Kent E. Carpenter
Keyword(s):  
Threatened Species ◽  
Environmental Changes ◽  
Extinction Risk ◽  
Conservation Status ◽  
Marine Species ◽  
Iucn Red List ◽  
Red List ◽  
Marine Biodiversity ◽  
Conservation Priorities ◽  
Conservation Action

Given the economic and cultural dependence on the marine environment in Oceania and a rapidly expanding human population, many marine species populations are in decline and may be vulnerable to extinction from a number of local and regional threats. IUCN Red List assessments, a widely used system for quantifying threats to species and assessing species extinction risk, have been completed for 1190 marine species in Oceania to date, including all known species of corals, mangroves, seagrasses, sea snakes, marine mammals, sea birds, sea turtles, sharks, and rays present in Oceania, plus all species in five important perciform fish groups. Many of the species in these groups are threatened by the modification or destruction of coastal habitats, overfishing from direct or indirect exploitation, pollution, and other ecological or environmental changes associated with climate change. Spatial analyses of threatened species highlight priority areas for both site- and species-specific conservation action. Although increased knowledge and use of newly available IUCN Red List assessments for marine species can greatly improve conservation priorities for marine species in Oceania, many important fish groups are still in urgent need of assessment.

Dietary composition of endangered seahorses determined by stable isotope analysis

2017 ◽  
Vol 68 (5) ◽  
pp. 831 ◽  
Author(s):  
S. Valladares ◽  
D. X. Soto ◽  
M. Planas
Keyword(s):  
Stable Isotope ◽  
Environmental Changes ◽  
Conservation Status ◽  
Management Strategies ◽  
Isotope Analysis ◽  
Primary Source ◽  
Habitat Characteristics ◽  
Conservation Actions ◽  
Isotope Mixing Models ◽  
North Western

The lack of integrated measures for assessing the feeding ecology of seahorses may restrict the effectiveness of conservation actions on wild populations of worldwide threatened seahorse species. Identifying dietary sources will allow researchers to determine their degree of vulnerability to environmental changes, redefine their conservation status and apply appropriate management strategies. The resource use of the seahorse Hippocampus guttulatus inhabiting coastal waters of Galicia (north-western Iberian Peninsula) was assessed for three populations and 2 years using stable isotope mixing models. The Bayesian mixing model (MixSIAR) estimated the relative contributions of the dietary sources to the seahorse diet and revealed that Caprellidea were the primary source, followed by Gammaridea and Caridea. Mysidae and Annelida represented the less dominant prey. This prey preference can be explained by the foraging behaviour of seahorses. Different contributions of Gammaridea and Caridea to the diet were found among sites, indicating different habitat characteristics and hence different habitat use by seahorses within each site. In addition, differences were encountered among sexes. Caprellidea was the dominant prey for females, whereas Gammaridea was the dominant prey for males. The findings of the present study will contribute to the knowledge of feeding patterns of H. guttulatus, providing relevant data for conservation of this endangered species.

scholarly journals Description of two new species of Avicularia Lamarck 1818 and redescription of Avicularia diversipes (C. L. Koch 1842) (Araneae, Theraphosidae, Aviculariinae)—three possibly threatened Brazilian species

Zootaxa ◽  
2009 ◽  
Vol 2223 (1) ◽  
pp. 25-47 ◽  
Author(s):  
ROGÉRIO BERTANI ◽  
CAROLINE SAYURI FUKUSHIMA
Keyword(s):  
New Species ◽  
Protected Areas ◽  
Conservation Status ◽  
Original Description ◽  
Color Pattern ◽  
Habitat Destruction ◽  
Southern State ◽  
Two New Species ◽  
Specimen Identification ◽  
Brazilian Atlantic Rainforest

Avicularia diversipes (C. L. Koch 1842) known previously only from its original description is redescribed along with Avicularia sooretama sp. nov. and Avicularia gamba sp. nov. The three species are endemic to Brazilian Atlantic rainforest. With other Avicularia species, they share a procurved anterior eye row, slender embolus and medially folded spermathecae, whereas they have unusual characters, such as a very long and spiraled embolus (A. diversipes) and spermathecae with multilobular apex (A. sooretama sp. nov.). Furthermore, the three species lack a tibial apophysis in males and share a distinctive color pattern ontogeny that is not known in any other Avicularia species. The conservation status of the three species is discussed, especially with respect to endemism, illegal trafficking and habitat destruction. The creation of protected areas in southern State of Bahia, Brazil, is recommended, as well as the inclusion of these species in IUCN and CITES lists. Appendices with figures and species information are presented to facilitate correct specimen identification by custom officers, in order to limit illegal traffic.

Sign in / Sign up

Export Citation Format

Share Document