Response of Marine Plankton Communities in Ponds to the Presence of Vertical Structures

The effects of bottom vertical structures like AquaMats® in enhancing plankton productivity was evaluated. One experimental earthen pond of 500 m2 was provided with AquaMats® increasing the surface substrate area 12 times and water quality, phytoplankton and zooplankton populations developed during almost 100 days was compared with a pond without AquaMats®. Their presence favored the development of Dinoflagellates (Miozoa, Dinophyceae), mostly Gymnodiniales, which may be of some concern since some species of this group have been associated with toxic algal blooms while in the ponds without AquaMats® Diatoms (Bacillariophyta) predominate. In both ponds plankton production was very much sculptured by external nutrients added to the systems. The balance between different nutrients is extremely important to regulate the phytoplankton populations with Diatoms blooming at silicate concentrations higher than 2 μM and below this level and at low nitrate and high ammonium being more appropriate for Dinoflagellates. The linkage between phytoplankton and zooplankton population in ponds is strong with zooplankton exerting control over the phytoplankton population and vice-versa. The use of vertical substrates enhances plankton productivity by increasing the substrate area for periphyton fixation. The main zooplankton taxonomic groups associated with the presence of AquaMats® were Calanoid and Harpacticoid copepodites and nauplii, veligers of gastropods and trochophore of polychaets, larval stages of organisms that except for calanoid copepods are benthic and correspond to the meroplanktonic phase in the life cycle of those organisms.

The Influence of Qatari Dust on the Element Composition of Marine Plankton

The Exclusive Economic Zone (EEZ) of Qatar is affected by extreme dust and extensive industrialization, making it an ideal location to examine influences of coastal processes on biological activity, which greatly affects marine biogeochemical cycling. In this study, the influence of dust on the trace element composition of plankton and how distance from shore effects elemental concentrations in marine plankton was investigated. Samples were collected using net tows with mesh sizes of 50 (bulkplankton) and 200 (zooplankton) mm size-fractions in 2012 and 2014 to examine temporal and spatial variabilities. The samples were strong acid digested and analyzed using ICP-OES. Trace metal clean techniques were used. The biogenic concentrations of trace metals were determined by correcting the bulk analyses for the lithogenic contribution using aluminum content of Qatari dust as a lithogenic tracer. The relative trace metal composition of plankton from EEZ of Qatar is Fe > Zn ≈ Cu > V ≈ Ni ≈ Cr ≈ As ≈ Mo > Cd ≈ Co. Small and large size planktonic compositions were similar, except for Ba, Mn, Pb, Mo which were higher in zooplankton than bulkplankton. It was not clear if the variability was due to differences in biology, proximity to the coast or interannual effects. The geochemical and statistical analysis suggested that the concentrations of Al, Fe, Cr, Co, Mn, Ni, Pb, Li in net-tow plankton samples were mostly of lithogenic (dust) and Cd, Cu, Mo, Zn, Ca are most likely of biogenic/anthropogenic origin. The excess concentrations relative to average dust from Qatar for most elements (except Cd) decreased with distance from shore. This may be due to contamination or uncertainties with the lithogenic correction or due to our sampling locations in a marginal sea, dominated by dust input. This is an aspect of this study that warrants more research.

Effects of different types of manure on the culture of marine plankton as a potential source of food for mariculture hatcheries

The study examined different types of organic manure on the culture of marine plankton as a potential source of food for rabbitfish, Siganus stellatus, larvae. Cow dung showed significantly higher species abundance and diversity of cultured marine plankton followed by chicken and finally mixed media manure (p<0.05). A total of 36 genera of phytoplankton (21) and zooplankton (15) were identified in all culture media. Class Bacillariophyta was the most abundant and diverse group which accounted for 41.3 % of the total phytoplankton. Calanoida was the dominant group of the identified zooplankton, accounting for 51.7 %. It was observed that the organic manure used favoured the growth of commercially important species of phytoplankton such as Chaetoceros sp., Skeletonema sp., Chlorella sp., Isochrysis sp., Nannochloropsis sp. and Spirulina sp., and zooplankton such as Eurytemora sp., Calanus sp., Oithona sp., Branchionus sp., Moina sp. and ostracods. The growth performance and survival rate of early stage rabbitfish larvae fed with live marine zooplankton performed better compared to those fed with Artemia spp. and commercial dry feed. This indicates that zooplankton have the potential to enhance growth performance and survival rate, hence increasing productivity and the development of mariculture.