Effect of seawater acidification on physiological and energy metabolism responses of the common Cockle (Anadara antiquata) of Gazi Bay, Kenya.

Ocean acidification (OA) is becoming a potential threat to marine organisms, especially in calcifying marine invertebrates. So far, along the Kenya Coast, there has been little research on the impact of OA on cockle (Anadara antiquata), particularly on their physiological impacts induced by exposure to acidified seawater. Hence, this study aimed to investigate the physiological and biochemical responses of Anadara antiquata under present and future predicted seawater pH. In this study, the Anadara antiquata was exposed to three pH treatments (pH 7.90, 7.60, and 7.30) for 8 weeks to mimic future OA and to understand the physiological and biochemical effects on the organisms. Condition index, energy reserves (glycogen and protein), and cellular damage (e.g., lipid peroxidation level) were measured. Condition index (CI) showed no significant difference at different pH treatments (pH 7.90, 7.60, and 7.30), whereas the survival Anadara antiquata was slightly reduced after 8 weeks of exposure to pH 7.30. Glycogen and protein content were not affected at reduced pH (7.60 and 7.30). However, after 8 weeks of exposure to pH 7.60 and 7.30, Anadara antiquata showed a slight decrease in lipid peroxidation, an indication of cellular damage. The physiological and biochemical parameters analyzed (glycogen and protein content; lipid peroxidation levels) showed useful biomarkers to assess ocean acidification impacts in cockle.

Pollution of the Niger Delta with total petroleum hydrocarbons, heavy metals and nutrients in relation to seasonal dynamics.

The African Niger Delta is among the world's most important wetlands in which the ecological effects of intensive oil exploitation and global change are not well documented. We characterized the seasonal dynamics and pollution with total-petroleum-hydrocarbons (TPHs), heavy-metals (HMs) and nutrient-loads in relation to climate-driven variables. High TPH concentrations up to 889 mg/L and HMs up to 13.119 mg/L were found in water samples, with pronounced spatio-temporal variation throughout the year. HM pollution index and contamination factor indicate serious ecological and human health hazards, especially for Cd, Cu, Hg, and Ni. Significant differences in TPHs/HMs were observed between sites and seasons, with correlations between TPHs-HMs, and climate-variables and TPHs-HMs. Nutrient levels, turbidity, salinity, temperature, and SO42- were high and interlinked with the variability of TPHs/HMs being greatest during wet season. These findings suggest an urgent need for improved pollution control in the Niger Delta taking into account the observed spatio-temporal variation and the exacerbation of effects in light of climate change. Given the high levels of contamination, further assessments of exposure effects and bioaccumulation in biota should include future climate change scenarios and effects on humans who intensively depend on the system for drinking water, food supply and livelihood.

Occurrence, distribution, and environmental risk of pharmaceutical residues in Mombasa peri-urban creeks, Kenya.

The information on pharmaceutical compounds' distribution and their possible risks in marine ecosystems along the Kenya coast is limited especially in the peri-urban creeks. Hence, this study aimed to determine pharmaceutical residue levels and distribution in selected peri-urban creeks in Mombasa and Gazi bay. The target compounds were analgesic (acetaminophen), antibiotics (trimethoprim and sulfamethoxazole), antiepileptic (carbamazepine), and antiretroviral (nevirapine). Pharmaceutical residues in grab surface seawater in wet and dry seasons ranged from below detection limit (BDL)-1065.6 µg L-1 and BDL-71.3 µg L-1, respectively. The concentration of the pharmaceutical residues was high in Tudor creek in the dry and wet seasons with a mean concentration of 63.3 µg L-1 and 233.1 µg L-1 respectively compared to Makupa creek (dry season, 54.2 µg L-1; wet season 16.2 µg L), and Mtwapa creek (dry season, 43.1 µg L-1; wet season, 15.0 µg L-1). Gazi Bay being used as a control site had a mean concentration of 21.3 µg L-1 and 3.1 µg L-1 during the dry season and wet season respectively. Acetaminophen and nevirapine were the most ubiquitous compounds in seawater since they were found in all seawater samples collected. Risk quotients (RQ) for invertebrates and algae based on the mean concentrations of the analytes were estimated to provide a preliminary environmental risk assessment. The results suggest that the studied acetaminophen, trimethoprim, sulfamethoxazole, and carbamazepine in seawater pose low (0.01 ≤ RQ < 0.1) to medium (0.1 ≤ RQ < 1) ecological risk whereas nevirapine poses medium to high (RQ ≥ 1) ecological risk to the ecosystems of Mombasa periurban creeks and Gazi bay. Further research, however, is encouraged on the distribution of pharmaceuticals in the marine environment and the long-term synergistic effects of mixtures of these compounds on marine biota.

The influence of monsoons on the spatial distribution and composition of floating marine litter.

Floating marine litter (FML) surveys were conducted in the near shore waters of Mombasa, Kilifi and Kwale Counties of Kenya through trawling using a manta net. A mean density of 26,665 ± 2869 items km-2 composed of 34.8% hard plastic, 40.5% soft plastics and 22.0% plastic lines/fibers was reported in this study. Litter densities in Kwale, Kilifi and Mombasa Counties were not influenced by monsoons, however, litter composition was influenced by monsoons with NEM and SEM being dominated mainly by hard plastics and soft plastics respectively. Litter categories diversity, evenness and richness were also not influenced by the monsoons during both NEM (1.01, 0.78 and 3, respectively) and SEM (1.09, 0.78 and 4, respectively). Fishing and recreational beaches had higher litter densities during NEM compared to SEM attributed to higher beach visitation and increased fishing activities during the calmer NEM season.

Temporal trends of marine litter in a tropical recreational beach: A case study of Mkomani beach, Kenya.

Six marine litter standing stock surveys were carried out to determine the influence of monsoon on the temporal abundance and composition of macro-litter in Mkomani beach, Mombasa Kenya. Foam (0.073 items m-2) and plastic (0.042 items m-2) fragments had the highest densities. The brand audit indicated that 66.9% of branded marine litter was of Kenyan origin. Food product packaging contributed 78.4% of the branded litter with PET bottles being the most abundant type of packaging (48.2%). Foreign products contributed 35.6% of branded marine litter during South East Monsoon (SEM) whereas only 11.7% during North-East Monsoon (NEM). Worth noting, PET packaging dominated during SEM (53.6%) compared to NEM (20.2%). Mkomani beach could be considered "extremely dirty" with a Clean-Coast Index greater than 20. The study concludes that monsoons influences litter diversity, richness and evenness.

The impacts of COVID-19 pandemic on marine litter pollution along the Kenyan Coast: A synthesis after 100 days following the first reported case in Kenya.

The contribution of COVID-19 pandemic to marine litter pollution was studied in Mombasa, Kilifi, and Kwale counties of Kenya, in June 2020 (100 days following the first confirmed case in Kenya). Standing stock surveys were conducted in 14 streets and 21 beaches while 157 transects were surveyed for floating litter. COVID-19 related items contributed up to 16.5% of the total litter encountered along the streets. The urban beaches (Mkomani and Nyali) had the highest quantities of COVID-19 related items (55.1% and 2.6% respectively) attributable to the ability to purchase single-use products and lifestyle. Most of the recreational beaches had no COVID-19 related products which could be attributed to the presidential directive on beach closure as a COVID-19 contingency measure. No COVID-19 related litter was found in the floating litter. Generally, beach closure and cessation of movement reduced the amount of litter that leaked to the marine environment.

Marine macro-litter composition and distribution along the Kenyan Coast: The first-ever documented study.

Macro-litter accumulation surveys were carried out in six beaches in Kilifi, Mombasa and Kwale Counties. Macro litter were collected, quantified and characterized to determine their composition, distribution and accumulation rates. The results showed that the accumulation rates ranged between 1.53 ± 1.23 and 11.46 ± 7.72 (for dry zones) and 2.69 ± 2.13 and 8.93 ± 7.87 items m-1 day-1 (for wet zones). Plastics and foam were the most abundant litter categories. Local products constituted about 88% of all the collected litter. Food packaging products constituted about 91.3% of all branded litter types. Marine litter pollution particularly by plastics was widespread in all studied coastal counties. However, a significant amount of litter encountered in the beaches was of local origin, thus a local solution to waste management (that will eliminate leakage into marine environments) will considerably reduce marine litter pollution in Kenya.

Baseline meso-litter pollution in selected coastal beaches of Kenya: Where do we concentrate our intervention efforts?

A total of 23 beaches were surveyed between July and September 2019. Meso-litter was collected by sieving sediment collected from 0.25 m2 quadrats laid along perpendicular transects through 5 mm mesh size sieves. The results showed that plastics were the most abundant litter encountered on all the beaches. Beaches close to urban areas had a higher number of litter categories (i.e. plastic, metal, foam, and paper) compared to the remote beaches that only had plastics. In conclusion, the lack of statistically significant evidence of the influence of proximity to urban centers, the predominant activity in the beaches, and exposure to wave action on the amount of meso-litter attest to the fact that marine litter pollution is a geographical spread problem that will require national, regional, and global action and approach to address. The intervention efforts (including beach clean-ups) should preferably target beaches that have back vegetation compared to those with seawalls.

Baseline survey of sediment contamination with 210Polonium in three peri-urban creeks of Mombasa, Kenya.

210Po in marine sediment from three peri-urban creeks in Mombasa was analyzed by alpha spectrometry in order to determine its baseline contamination levels. The mean 210Po activity in marine sediment from Mtwapa, Tudor and Makupa creeks were 18.67 ± 1.8, 21.17 ± 2.2 and 13.09 ± 1.6 Bq Kg-1 dw, for surface sediment and 37.56 ± 2.14, 28.64 ± 2.86 and 30.42 ± 2.1 Bq Kg-1 dw respectively, for sediment cores. Comparison of 210Po activity in surface sediment indicated that 210Po in the creeks could be originating from the same source. However, comparison of activities in the entire cores from the three creeks indicated that 210Po sources could have been different in the past. 210Po activities in this study were relatively elevated compared to marine environments under similar anthropogenic influence and there is need to understand its source and fate.