Distribution,biology and hybridization of Scaphirhynchus albus and S. platorynchus in the Missouri and Mississippi rivers

Synopsis Scaphirhynchus albus and S. platorynchus were studied in Missouri during 1978–1979 to assess their distribution and abundance, to obtain information on their life histories, and to identify existing or potential threats to their survival. S. platorynchus was collected in substantial numbers (4355 specimens) at all 12 sampling stations in the Missouri and Mississippi rivers, while only 11 S. albus were captured from 6 stations. Twelve specimens identified in the field as hybrids between the two species were captured from 4 stations. Morphometric and meristic comparisons of presumed hybrids with the parent species, using cluster and principal components analyses, demonstrated intermediacy of most specimens identified in the field as hybrids. Aquatic insects comprised most of the diet of S. platorynchus and S. albus, but S. albus and the hybrids had consumed considerable quantities of fish. S. albus grew more rapidly than S. platorynchus, while the growth of hybrids was intermediate. Hybridization appears to be a recent phenomenon, resulting from man-caused changes in the big-river environment. Hybridization may be a threat to survival of S. albus in the study streams.     

Assessing threats and mapping sandal resources to identify genetic ‘hot-spot’ for in-situ conservation in peninsular India

Santalum album L. is an economically important tropical tree species. Owing to extensive logging, changes in land-use patterns and poor natural regeneration, the natural sandal populations are rapidly dwindling. It is feared that such threats could easily undermine the genetic diversity of sandal populations. Effective measures to prevent such loss are prerequisite. We have developed baseline data on the levels of genetic diversity and its distribution on a geographic scale for sandal in India. Based on Geographic Information System, distribution map of sandal was developed and found that the populations were geographically more concentrated in the Deccan plateau. It was found that, for past 53 years, there was a monotonic decrease in the extraction of sandal in the state of Karnataka, India. Using allozyme markers, the genetic diversity of 19 sandal populations in peninsular India were determined and over all observed heterzygosity (H_o) was found to be 31%. The percent H_o was positively correlated with the density of the sandal populations (r = 0.44) and with increasing longitude it was found to be negatively correlated (r = −0.51). The dendrogram analysis indicated a clear clustering of sandal populations based on their geographic occurrence. The Deccan plateau populations were found to be genetically the most diverse and seemed to represent the ‘hot-spot’ of sandal genetic resources in peninsular India. Our results have important implications for the conservation strategies for sandal populations in peninsular India and can be applied for the conservation of other taxa as well.     

Distribution and abundance of marine turtles in the Socialist Republic of Viet Nam

To establish baseline data on the distribution, abundance and threats to marine turtles in Viet Nam we conducted surveys with local fishers, community members and provincial Ministry of Fisheries staff from 17 of Viet Nam’s 29 coastal provinces. These data indicate that five species of marine turtle reside in Viet Nam’s waters (loggerhead, olive ridley, leatherback, green and hawksbill turtles), and four species nest on Viet Nam’s beaches (all of the above except the loggerhead turtle). It is evident from these data that significant declines have occurred in both foraging and nesting populations of all five marine turtle species found in Viet Nam. The greatest current threats to marine turtle populations in Viet Nam are habitat degradation, the accidental and opportunistic of turtles capture by fishers and the direct take of nesting females and their eggs. Successful conservation efforts have been made in recent years through collaboration between international Non Government Organisations and several Vietnamese Government Ministries. Continued success of these projects and the development and implementation of marine conservation policy will depend upon building awareness among Government employees, fishers and the general public about marine turtle biology, ecology, and the need to protect them.     

Attitudes of Scottish City Inhabitants to Cetacean Conservation

In 2003, a survey was conducted in two major Scottish cities in order to investigate current perceptions of the public towards cetaceans and their conservation. Public concern about cetacean conservation was high. Overall the issues considered to be the greatest threats to cetacean populations were related to pollution: oil spills, and chemical and sewage pollution (serious threat: 68, 65, and 63%, respectively). Concern was also high regarding the depletion of cetacean prey from over-fishing, entanglement in fishing gear, marine litter and global warming, (serious threat: 54, 51, 44, and 43%, respectively). Conservation issues that are of specific concern to Scottish waters were also noted: military activities, fish farming and oil exploration. Least concern was expressed about whale-watching (not a threat: 48%). Women and older respondents expressed significantly higher levels of concern about cetacean conservation. Generally, the opinions of the public were similar to those of a test group of marine conservation professionals and advocates, although the public tended to show slightly greater levels of concern for most issues. However, the public expressed significantly higher levels of concern over oil spills, sewage pollution and chemical pollution than did marine conservation professionals/advocates. Most participants (60%) were unsure as to whether there was currently sufficient legal protection for cetaceans in Scotland, but eight out of ten respondents thought that there should be legislation specifically for cetacean conservation. Moreover, 40% stated that the proposal of a law specifically for the protection of cetaceans would make them view a political party or politician more favourably. Eighty percent of those interviewed were in favour of seeing more marine environmental education, including information on cetaceans and their environment, in the Scottish school curriculum.     

Population structure and conservation of the coastal palm Coccothrinax borhidiana (Arecaceae) in the northwest of Cuba

Coccothrinax borhidiana is among the top 50 most threatened plants of Cuba. This palm is endemic to Punta Guanos-Punta Seboruco, Matanzas. Given the increase of gas-oil exploitation in the area where this palm population grows, the current situation of the species could be much more serious than what is known. We characterized the population structure based on a systematic sampling of 100 plots and evaluated the existing threats for re-evaluating its conservation status and proposing a recovery strategy. We sampled 685 individuals, 44.2 % juveniles and 55.8 % adults, whose population structure in 10 size classes did not conform to a log-normal distribution. This indicates that reproduction and/or recruitment processes are reduced, due to deforestation for the gas-oil industry, road construction and the establishment of small-holder, as well as the effect of cattle ranching and frequent fires. However, the higher representation of individuals in the three smaller size classes shows regeneration, which is observed in areas abandoned by the gas-oil industry. Despite this, existing threats have significantly reduced the area of occupancy of the species, and it is estimated that it will continue to decline by up to 80 %, making the species Critically Endangered. For these reasons, immediate management actions are needed to minimize the effect of threats on C. borhidiana, as well as to secure the management and implementation of ex situ conservation strategies that will allow the establishment of a new subpopulation in a nearby and ecologically similar area, which has the necessary legal protection status.     

Effects of herbivores, nutrient enrichment, and their interactions on macroalgal proliferation and coral growth

We conducted a 20-week manipulative field experiment on shallow forereefs of the Florida Keys to assess the separate and interactive effects of herbivory and nutrient enrichment on the development of macroalgal communities and the fitness of the corals Porites porites and Siderastrea siderea. Excluding large herbivorous fishes produced macrophyte blooms both with and without nutrient enrichment. In contrast, there were no direct effects of nutrient enrichment. There were, however, small, but significant, interactive effects of herbivory and enrichment on macroalgal cover. Following nutrient enrichment, total macroalgae and the common seaweeds Dictyota spp. were suppressed in the presence, but not in the absence, of large herbivorous fishes—suggesting that fishes were selectively feeding on nutrient-enriched macrophytes. Access by large herbivores prevented algal overgrowth of corals, but these large fishes also directly grazed both corals. Excluding fishes did not alter survivorship of either coral species, but did decrease parrotfish grazing scars on both corals and increased the net growth of P. porites. Nutrient additions had no direct effects on the survivorship of corals, but there was a trend (P = 0.097) for nutrients to stimulate the growth of P. porites. The preponderance of experiments available to date indicates that loss of key herbivores is a major factor driving macroalgal blooms on coral reefs; anthropogenic nutrient pollution generally plays a more minor role.     

The distribution and state of mangroves along the coast of Transkei,Eastern Cape Province,South Africa

The mangrove communities along the coastline of the former Transkei, now part of the Eastern Cape Province, have not been looked at in detail since Ward and Steinkes survey in 1982. Mangroves previously occurred in 17 estuaries but were now found in only 14 of the 76 estuaries visited, with a complete loss of mangroves evident in the Mnyameni, Mzimvubu and Bulungula estuaries amounting to 7.5 ha. Total mangrove loss amounted to 17.6 ha which represents a 6.5% loss over 17 years or 1.04 ha per annum. Tree cover had increased by 16.15 ha in eight other estuaries. This increase could be attributed to the inaccessibility of mangrove stands or to protection afforded by provincial nature reserves and hotel resorts. No new mangrove stands were recorded, although Steinke (pers. comm.) has recently recorded mangroves along the north bank of the Kei River. There has been little change in mangrove species composition in the different estuaries over the past 17 years. Total mangrove loss amounted to 17.6 ha which represents a 6.5% loss over 17 years or 1.04 ha per annum and the species recorded included Avicennia marina, Bruguiera gymnorhiza and Rhizophora mucronata. The mangrove fern Acrostichum aureum L. was recorded for the first time in the Mkozi estuary. Tree density for all estuaries was between 10 and 2594 trees ha^–1. The Mngazana and Mntafufu estuaries had the highest tree densities of 2594 and 1402 trees ha^–1 respectively, typical of riverine mangrove forests. Fringe mangroves were evident in most other systems. Removal of trees for wood has the greatest impact on mangrove cover. Fringe mangrove stands are particularly accessible to harvesters. Only 6% of the current area of trees is afforded some protection in conservation areas. The Mdumbi, Mzamba and Kobonqaba estuaries receive no conservation protection and harvesting has resulted in more than 50% of the trees being removed. The density of dead tree stumps was greater than the number of living trees and no seedlings or juvenile trees were found. Further removal of mangroves within the estuaries south of the Mzimvubu River is expected in the fringe mangroves, as most are unprotected and easily accessible.     

Dendrometric characteristics as indicators of pressure of Afzelia africana Sm. dynamic changes in trees found in different climatic zones of Benin

Afzelia africana is a forest species used by local inhabitants for various purposes, especially as forage to feed cattle, as medicinal plant and its wood is used to make furniture or for cooking. Its utilisation in its current form constitutes a threat to this species. However, the lack of data on this species is a hindrance towards drawing up an efficient program for its sustainable management. In order to fill in some gaps in the knowledge of A. africana tree populations, dendrometric characteristics of this species were studied within different climatic zones where it occurs in Benin. Data collected on each of them included height and diameter, and with regard to the levels of pressure, five categories were defined namely: null, weak, moderate, severe and very severe. As far as diameter is concerned every size was taken into consideration in all the climatic zones. However, average diameter and height of the A. africana individuals varied significantly according to climatic zones. Anthropogenic pressure increased while moving from the humid zone towards the drier zone. Moreover, there was a noticeable significant change in the level and quality of pressure between trees found in the different climatic zones in the sense that the lower the height of the trees, the more severe the level of pressure exerted. Such a relationship was not significant when one considers tree diameter in accordance with the climatic zones in the country.     

Fish fauna of Chalakudy River,part of Western Ghats biodiversity hotspot,Kerala, India: patterns of distribution,threats and conservation needs

Seventy one fish species belonging to 27 families and 50 genera were collected from various sampling sites spread along the upstream and downstream parts of the Chalakudy river, in the Western Ghats biodiversity hotspot in Kerala, South India. Cyprinids were the most dominant group represented by 24 species belonging to 13 genera, followed by the catfishes of the family Bagridae (7 species from 2 genera) and loaches belonging to the family Balitoridae (5 species from 5 genera). Of the 71 species, 4 belong to the ‘critically endangered’ (CR) and 16 to the ‘endangered’ (EN) category. 3 of the critically endangered species are strictly endemic to the Chalakudy river system. We also collected 5 exotic species several of them categorized as potential pest. Fish species richness (FSR) showed a direct relationship with increasing stream order with maximum values observed in the downstream/low elevation regions. Considerable differences were observed in the FSR between different microhabitats with maximum values observed in bed rock and pool riffle and the lowest in regimes followed by step pools. Diversity and species richness decreased with increasing altitude and higher diversity and species richness were observed in sampling sites located between 0–200 m above sea level. A definite temporal partitioning was also observed with regard to FSR with higher richness during the day time and the lowest observed at dawn. Indiscriminate collection of endemic and threatened ornamental fish species for export, exploitation of endangered food fishes by forest-dwelling communities and local fisher folk, pollution, loss of riparian cover, damming and exotic species threaten the rich ichthyofaunal diversity of Chalakudy River. An urgent need exists for studying the life history traits and demography of the most important endemic and threatened fishes, as lack of information on these aspects have significantly affected conservation efforts. The implementation of strong management strategies like fixing total allowable catch (TAC), and the use of quotas are needed to reduce the overall collection pressure with regard to the trade in native ornamental species from the river.     

Biological diversity of the Yala Swamp lakes, with special emphasis on fish species composition, in relation to changes in the Lake Victoria Basin (Kenya): threats and conservation measures

During the second half of the last century, the Lake Victoria ecosystem has undergone drastic ecological changes. Most notable has been the decline in the populations of many endemic cichlid fishes. The lake has lost nearly 200 haplochromines and one tilapiine, Oreochromis esculentus. The above changes have been attributed to effects of species stocking and, in particular, from predation pressure by the introduced Nile perch, Lates niloticus. Other factors that have led to the decline of the endemic species include intensive non-selective fishing, extreme changes in the drainage basin, increased eutrophication, and the invasion of the lake by the water hyacinth, Eichhornia crassipes. However, the remnants of some species that had disappeared from Lake Victoria occur abundantly in the Yala Swamp lakes (Kanyaboli, Sare and Namboyo). This paper discusses the biodiversity of the swamp and the three lakes and gives suggestions for their conservation.