Overview of Environmental Hazards and Health Effects of Pollution in Developing Countries: A Case Study of Nigeria

Pollution has taken on a global dimension, and the effects are most obvious in developing countries. The effects take a toll on human health, animals, and vegetation, as well as on soil, air, and water quality. The objective of this article is to discuss the current relationships among pollution, environmental quality, and human health within the frame of anthropogenic activities in developing countries. In addition to personal observations, we review relevant literature on conditions throughout the developing world and case studies on conditions and activities in Nigeria. Key findings show the significant, adverse contributions to human health and environmental risk from current waste generation and handling practices, indoor and outdoor air pollution, wastewater and effluent generation and disposal, the hazardous nature and pollution potential of wastes, and the human behaviors that contribute to pollution in developing countries. There is an urgent need to create awareness among the various segments of society of the human health hazards posed by pollution as well as a need for the comprehensive development and enforcement of appropriate policies to prevent a descent into an abyss of deteriorating human and environmental health.     

A rare case of de novo structural rearrangement of X chromosome diagnosed by amniocentesis

A dicentric X chromosome was found in a female fetus during cytogenetic studies performed on amniotic cells. Blood samples from the parents showed normal karyotypes and the pregnancy was terminated. The mechanism for the formation of this ‘de novo’ rearrangement is discussed.     

Resting spore formation and biochemical composition of the marine planktonic diatom Chaetoceros pseudocurvisetus in culture: ecological significance of decreased nucleotide content and activation of the xanthophyll cycle by resting spore formation

The biochemical composition of vegetative cells and resting spores of Chaetoceros pseudocurvisetus Mangin was compared in cultures under various nutrient and light conditions. The cellular content of major nucleotides such as AMP, ADP, ATP and UTP decreased in the order: vegetative cells, nutrient-starved (vegetative) cells and resting spores, indicating that the general metabolism of resting spores is relatively inactive. ADP-glucose was only abundant in nutrient-starved vegetative cells, suggesting metabolic imbalance in these cells. The chl a–specific fluorescence yield of vegetative cells grown under all culture conditions was low, but very high in resting spores. The ratios of the cellular contents of diadinoxanthin to chl a and of diatoxanthin to chl a were higher in resting spores and nutrient-starved vegetative cells than in nutrient-replete vegetative cells. The diadinoxanthin–diatoxanthin xanthophyll cycle was active in resting spores; the xanthophyll cycle was synchronized with a 14 h light:10 h dark photoperiod. Also, the ratios of cellular content of diadinoxanthin and diatoxanthin to cellular content of chl a in resting spores were relatively high in high irradiance, and decreased gradually in conditions of darkness over long culture periods. Under conditions of strong light and high temperature, most resting spores survived more than 40 d while nutrient-starved vegetative cells died within 33 d. These results suggest that resting spore formation is a strategy for enhancing protection and lowering metabolic rate for survival. These physiological changes accompanying spore formation enable resting spores not only to overwinter but also to “oversummer” in the coastal euphotic layer. Received: 23 March 1999 / Accepted: 11 August 1999     

Blue mussels, Mytilus edulis, at the edge of the range: population structure, growth and biomass along a salinity gradient in the north-eastern Baltic Sea

The blue mussel, Mytilus edulis, is the most conspicuous animal species in the northern Baltic rocky sublittoral. In the studied area the species lives at the margin of its salinity tolerance. Although dwarfed by the low-salinity conditions, blue mussels in the northern Baltic are very abundant and have a decisive role in the benthic and pelagic ecosystems. We studied abundance, size distribution, biomass and growth rate of blue mussels along a 270 km salinity gradient in the northern Baltic Sea. Samples (n=317, 1998-1999) from moderately exposed and exposed rocky shores at seven study areas were collected in the southern Archipelago Sea in the west and into the central Gulf of Finland in the east, where the species is becoming increasingly rare. The results show a marked decline in mean mussel size and biomass from the saline west to the less saline east. The growth rate also decreased with lower ambient salinity. However, abundance of small mussels was considerably higher in the central and eastern parts of the study area. Vertically, the highest biomass was recorded at intermediate depths (5 and 8 m), being lower at both shallower (3 m) and deeper bottoms (12 m). It is concluded that salinity is the foremost factor determining size structure and growth rate among populations within the area. The results suggest that predation further influences the population structure of blue mussels living at the edge of their range in the central Gulf of Finland ultimately set by their salinity tolerance.     

Gene flow via the dispersal of fertilizing sperm in a colonial ascidian (Botryllus schlosseri): the effect of male density

In marine invertebrate taxa with restricted larval dispersal, the movement of fertilizing sperm may contribute significantly to gene flow. Several recent studies have examined the ability of isolated males to fertilize eggs as a function of distance, but none has explicitly considered the effect of other males in the vicinity on the spatial distribution of fertilizations obtained by a male. I assayed the effect of additional males on the fertilization success of male Botryllus schlosseri (Pallas) colonies with respect to distance via an in situ mating experiment performed in Maine, USA during the summer of 1993. Allozyme markers were used to assay paternity. The presence of additional males reduced the ability of a focal male to fertilize eggs in all distance classes. This suggests that competition for fertilizations among males will reduce gene flow via sperm dispersal and that the fertilization success of isolated males may over-estimate gene flow via sperm dispersal in many natural populations.     

Distribution,population structure,growth and reproduction of the roundnose grenadierCoryphaenoides rupestris (Pisces: Macrouridae) in the deep waters of the Skagerrak

The roundnose grenadierCoryphaenoides rupestris Gunnerus, 1765 occurs benthopelagically in the deepest parts of the Norwegian Deep, i.e., at depths >300 m in the Skagerrak. Based on studies of distribution carried out in the years 1984 to 1987, it appears that the concentrations contitute a largely self-sustaining population. From age-readings using transverse otolith sections, the population appears to consist of at least 50 to 60 age-groups and to include a very high proportion of old fish. Population growth-curves in terms of length and weight revealed that females grow comparatively fast for a longer time and attain greater asymptotic sizes than males. Maximum lengths appear however to be lower in the Skagerrak than in waters to the west of Scotland, and the length/weight data indicate that the weight at a given length (weight at length) of large individuals is less than reported from other areas. The major spawning season is in late autumn, probably extending into early winter. Fifty per-cent of females and males become mature for the first time at Age 10 and 8 yr, respectively. Corresponding pre-anal lengths are 11 and 8.5 cm.     

Slowest of the slow: latitudinal insensitivity of burrowing capacity in the bivalve <Emphasis Type="Italic">Laternula</Emphasis>

Low temperature limits the rate of biochemical reactions and aerobic scopes of cold water ectotherms. To compensate for this limiting effect, animals living in cold environments often possess physiological or morphological adaptations to maintain vital functions. Cross-latitudinal comparison of aerobic capacities is one method to test which factors constrain activity in thermally distinct environments particularly when congeneric studies are carried out on related species with conservative ecology and habitat. Burrowing is a major aerobic activity of bivalve molluscs that is described here for the first time for the tropical mangrove species Laternula truncata and Laternula boschasina and then compared with their Antarctic congener Laternula elliptica. About 80% of L. truncata (16.3–46.1 mm shell length) and 63% of L. boschasina (11.3–27.7 mm shell length) buried within 24 h at 28°C. The burrowing rate index (BRI = [³√wet weight/time to bury]×10⁴) ranged between 1.1 and 20.2 for L. boschasina and 1.1–32.9 for L. truncata. These values are 2–3 orders of magnitude less than other tropical bivalve molluscs and are amongst the lowest recorded for any bivalve. Comparisons with the Antarctic L. elliptica showed little or no differences in BRI (Q ₁₀ of 1.0–1.2 for specimens of the same size). This is contrary to the general pattern over a wide range of bivalves, where BRI increases with a Q ₁₀ of between 2.9 and 6.4 between high latitudes and the equator. L. elliptica has 25–30% longer relative foot length than tropical congeners of the same size, which could be a morphological adaptation compensating for reduced burrowing speeds in a colder environment. Burrowing rates within the genus Laternula could, however, also be maintained by differing habitat, ecological and physiological constraints on burrowing capability.