Zooplankton Samples Research Articles

Temporal Variation and Spatial Distribution in the Water Environment Helps Explain Seasonal Dynamics of Zooplankton in River-Type Reservoir

Integrated assessment of the water environment has become widespread in many rivers, lakes, and reservoirs; however, aquatic organisms in freshwater are often overlooked in this process. Zooplankton, as primary consumers, are sensitive and responsive to changes in the water environment. Water and zooplankton samples were collected on-site at Shanxi Reservoir quarterly to determine 12 water environmental indicators and to quantify the abundance of zooplankton of Cladocera, Copepoda and Rotifera by using the ZooScan zooplankton image-scanning analysis system, combined with OLYMPUS BX51 using machine learning recognition classification. The aim was to explore the relationship between water environmental factors and zooplankton through their spatial and temporal heterogeneity. Through principal component analysis, redundancy analysis and cluster analysis, variations in the factors driving zooplankton population growth in different seasons could be identified. At the same time, different taxa of zooplankton can form clusters with related water environmental factors during the abundant water period in summer and the dry water period in winter. Based on long-term monitoring, zooplankton can be used as a comprehensive indicator for water environment and water ecological health evaluation, as well as providing scientific support for regional water resources deployment and management.

The use of an automated organism tracking microscope in mesocosm experiments

AbstractA method for automatically counting and measuring sizes and motility behavior of zooplankton and phytoplankton in water samples is presented. Two video cameras are focused on separate optical chambers of different sizes. The chambers are filled and emptied repeatedly by synchronized pumps. Real‐time motion analysis is performed by computer on the respective video feeds. Fluorescence from chlorophyll a (Chl a) is imaged at single pixel resolution. Measured parameters for individual organisms include size, swimming velocity, motility patterns, and chlorophyll fluorescence density. The system was tested during a mesocosm experiment where it was mounted on one of several mesocosm columns. The results were validated against Chl a measurements and microscopy counts. A sampling interval of 1 per day revealed detailed dynamics of chlorophyll activity as well as shifts in both the phytoplankton and zooplankton community structure over the course of a month. A helix coefficient, a metric related to organism motility behavior, showed substantial variation over time, consistent with changing plankton communities. Sampling rates as frequent as 1 per hour enables detailed analysis of diurnal vertical migration and similar phenomena at fixed sampling points.

Temporal dynamics in zooplankton δ13C and δ15N isoscapes for the North Atlantic Ocean: Decadal cycles, seasonality, and implications for predator ecology

The limited amount of ecological data covering offshore parts of the ocean impedes our ability to understand and anticipate the impact of anthropogenic stressors on pelagic marine ecosystems. Isoscapes, i.e., spatial models of the distribution of stable isotope ratios, have been employed in the recent years to investigate spatio-temporal patterns in biogeochemical process and ecological responses. Development of isoscapes on the scale of ocean basins is hampered by access to suitable reference samples. Here we draw on archived material from long-running plankton survey initiatives, to build temporally explicit isoscape models for the North Atlantic Ocean (> 40°N). A total of 570 zooplankton samples were retrieved from Continuous Plankton Recorder archives and analysed for δ13C and δ15N values. Bayesian generalised additive models were developed to (1) model the relations between isotopic values and a set of predictors and (2) predict isotopic values for the whole of the study area. We produced yearly and seasonal isoscape models for the period 1998–2020. These are the first observation-based time-resolved C and N isoscapes developed at the scale of the North Atlantic Ocean. Drawing on the Stable Isotope Trajectory Analysis framework, we identify five isotopically distinct regions. We discuss the hydro-biogeochemical processes that likely explain theses modes, the differences in temporal dynamics (stability and cycles) and compare our results with previous bioregionalization efforts. Finally, we lay down the basis for using the isoscapes as a tool to define predator distributions and their interactions with the trophic environment. The isoscapes developed in this study have the potential to update our knowledge of marine predator ecology and therefore our capacity to improve their conservation in the future.

I’m not that Shallow – Different Zooplankton Abundance but Similar Community Composition Between Habitats in the San Francisco Estuary

Wetland restoration is a key management tool for increasing food availability for at-risk fishes in the San Francisco Estuary. To characterize the benefits of restoration sites, it is critical to quantify the abundance and composition of fish food resources in and near the wetlands. Characterization of zooplankton communities is considered particularly important, but accurate analysis of zooplankton samples is time-consuming and expensive. The recently established Fish Restoration Program (FRP) Monitoring Team assessed whether data from existing long-term monitoring surveys could be used to characterize shallow-water zooplankton communities before restoration. During the springs of 2017 to 2019, the FRP collected zooplankton samples near the mouth of tidal wetland sites, or immediately outside future restoration sites, and compared them to concurrent samples collected in deep water by existing long-term monitoring surveys. We found very few differences in community composition between shallow and deep samples, though a few taxa were more abundant in shallow water. Seasonal and interannual differences in composition and abundance showed that restoration sites provide varying food resources over time. There was significantly higher total abundance of zooplankton in deep versus shallow water, which may be a result of differences in zooplankton production, migration, or fish predation. Inconsistencies in towing speed and gear type may also be driving this result, rather than true habitat differences. This study indicates that monitoring of wetland restoration sites must rely on multiple years of data collected on the site—rather than relying on adjacent open-water sampling—and should include monitoring of epiphytic and epibenthic invertebrates as well as zooplankton.

Plankton population dynamics and methylmercury bioaccumulation in the pelagic food web of mine-impacted surface water reservoirs

Thermal stratification of reservoirs can lead to anaerobic conditions that facilitate the microbial conversion of mercury (Hg) to neurotoxic and bioaccumulative methylmercury (MeHg). But MeHg production is just the first step in a complex set of processes that affect MeHg in fish. Of particular relevance is uptake into suspended particulate matter (SPM) and zooplankton at the base of the pelagic food web. We assessed plankton dynamics and Hg uptake into the pelagic food web of four Hg-impaired California water reservoirs. Combining water chemistry, plankton taxonomy, and stable carbon (C) and nitrogen (N) isotope values of SPM and zooplankton samples, we investigated differences among the reservoirs that may contribute to differing patterns in MeHg bioaccumulation. Methylmercury accumulated in SPM during the spring and summer seasons. Percent MeHg (MeHg/Hg*100%) in SPM was negatively associated with δ15N values, suggesting that “fresh” algal biomass could support the production and bioaccumulation of MeHg. Zooplankton δ13C values were correlated with SPM δ13C values in the epilimnion, suggesting that zooplankton primarily feed in surface waters. However, zooplankton MeHg was poorly associated with MeHg in SPM. Our results demonstrate seasonal patterns in biological MeHg uptake and how multiple data sources can help constrain the drivers of MeHg bioaccumulation.

Allometric scaling of interspecific RNA transcript abundance to extend the use of metatranscriptomics in characterizing complex communities.

Metatranscriptomics allows profiling of community mRNA and rRNA transcript abundance under certain environmental conditions. However, variations in the proportion of RNA transcripts across different community size structures remain less explained, thus limiting the possible applications of metatranscriptomics in community studies. Here, we extended the assumptions of the growth-rate hypothesis (GRH) and the metabolic theory of ecology (MTE) to validate the allometric scaling of interspecific RNA transcript (mRNA and rRNA) abundance through metatranscriptomic analysis of mock communities consisting of model organisms. The results suggest that body size imposes significant constraints on RNA transcript abundance. Interestingly, the relationship between the total mitochondrial transcript abundance (mRNA and rRNA slopes were -0.30 and -0.28, respectively) and body size aligned with the MTE assumptions with slopes close to -¼, while the nuclear transcripts displayed much steeper slopes (mRNA and rRNA slopes were -0.33 and -0.40, respectively). The assumed temperature dependence was not observed in this study. At the gene level, the allometric slopes range from 0 to -1. Overall, the above results showed that larger individuals have lesser RNA transcript abundance per tissue mass than smaller ones regardless of temperature. Analyses of field-collected microcrustacean zooplankton samples demonstrated that the correction of size effect, using the allometric exponents derived from the model organism mock community, explains better the patterns of interspecific RNA transcripts abundance within the metatranscriptome. Integrating allometry with metatranscriptomics can extend the use of RNA transcript reads in estimating ecological processes within complex communities.

ASSESSMENT OF ZOOPLANKTON DIVERSITY OF NEW CONSTRUCTED RESERVOIR BISNOOR PACHDHAR RESERVOIR IN DISTRICT, BETUL, MP

The status of healthiness of any freshwater ecosystem is basically depends on the diversity and density of zooplankton inhabiting the freshwater resources. Zooplanktons are considered as fundamental source for primary consumer in any aquatic environment. Which influence greatest scope in decisive the total productivity of freshwater body. The present study is attempted to the qualitative and quantitative distribution of zooplankton in different sites of Bisnoor Pachdhar reservoir. The study was carried out seasonally from July 2020 to June 2021. The whole assessment was divided into four major seasons viz monsoon, post monsoon, winter and summer. The compilation of the zooplankton samples and their qualitative and quantitative was through followed the standard procedures of limnological analysis. During the study period sequence of dominant groups Rotifera > Copepoda > Protozoa > Cladocera > Ostracoda was observed at dam site and mid site of all season. On another hand at tail end site major dominant group was Copepoda > Protozoa > Cladocera > Rotifera > Ostracoda noted during monsoon, post monsoon and winter and during summer the order of dominant group Copepoda > Rotifera > Protozoa > Ostracoda > Cladocera was recorded in Bisnoor Pachdhar reservoir.

Identification and observations of parasitic isopod larvae (Isopoda: Epicaridea) from the northeastern Pacific: pelagic distribution and association with copepod intermediate hosts

Abstract Zooplankton samples from the northeastern Pacific, USA were analyzed to identify and determine the abundance and distribution of parasitic isopod larvae and copepod hosts. Vertically stratified samples were collected at stations spanning the continental shelf off Oregon, USA. Two species of epicarideans were identified: Hemioniscus balaniBuchholz, 1866 (endoparasite of barnacles) and Argeia pugettensisDana, 1853 (ectoparasite of shrimps). Cryptoniscus larvae of these species can be distinguished based on the antennae (four basal and five flagellar articles in H. balani, four basal and four flagellar articles in A. pugettensis), tooth-like structures on the antennules and coxal teeth (present in H. balani, lacking in A. pugettensis), and pereopods (1, 2 gnathopodal and 5, 6 ambulatory in H. balani, all gnathopodal in A. pugettensis). Epicaridean larvae were rare in zooplankton samples with concentrations up to 10 m–3. Larvae were often found within 10 km of shore, with highest concentrations below the Ekman layer at 20–50 m depth near the bottom and between the 8 and 10°C isotherms. Likely as a result of dislodgment, only 26 copepods with epicaridium or microniscus larvae attached were confirmed. Larvae were mostly (78%) found attached to two species of Acartia, suggesting they were the preferred host, but five other genera of copepods were documented as hosts. The concentration of copepods and larvae exhibited a significant positive correlation when the analysis was limited to stations where both larvae and copepods were caught. The distribution of host copepods was significantly shallower than epicaridean larvae and generally closer to shore. The planktonic phase of the life cycle of epicarideans remains a black box for most of the +860 known species. Future work should include molecular data to link their larval and adult life cycle stages and connect the parasites with their intermediate hosts.

Diet and trophic interactions of Mediterranean planktivorous fishes

Diet and trophic interactions of seven species of planktivorous fishes: European anchovy Engraulis encrasicolus, European sardine Sardina pilchardus, round sardinella Sardinella aurita, European sprat Sprattus sprattus, red bandfish Cepola macrophthalma, damselfish Chromis chromis and bogue Boops boops were studied in the Bay of Marseille (North-Western Mediterranean Sea) from March to September 2017. Taxonomic composition and size distribution of prey were studied using stomach content analysis, and compared to prey availability determined by continuous zooplankton sampling at a fixed point. Frequently consumed items included copepods, decapod larvae and fish eggs. Comparatively, E. encrasicolus consumed more calanoid copepods (i.e. Centropages spp.), S. pilchardus, S. aurita and S. sprattus consumed more harpacticoid copepods (i.e. Microsetella/Macrosetella spp.), C. macrophthalma consumed more decapod larvae, C. chromis consumed more pteropods and B. boops consumed more benthic polychaetes. Sardina pilchardus consumed the widest diversity of prey. Prey size distribution and average prey size significantly differed among species. The prey–predator size ratio (PPSR) was highest for B. boops and lowest for S. aurita. Carbon and nitrogen stable isotope composition of species overlapped, probably due to the ingestion of particulate organic matter from the same sources at the base of the planktonic food web in the Bay of Marseille. Furthermore, trophic niche overlap supported the hypothesis of potential trophic competition between Engraulidae and Clupeidae.

A database of zooplankton abundance in the Atlantic sectors of the Southern and sub-Arctic Oceans

SummaryScientific sampling of zooplankton in the Atlantic sector of the Southern Ocean has been undertaken since the 1920s, but few analyzed datasets are available to the research community. We provide a database of standardized data derived from samples collected by Bongo nets in this sector between 1996 and 2013, amounting to almost 94,000 individual records. The study region contains some of the highest levels of pelagic biomass in the Southern Ocean and is also undergoing rapid ocean warming and changing seasonality in sea-ice distribution. Data from a single expedition to the sub-Arctic where the same sampling methodology was used are also included. Atlantic water is an increasing influence in that region, as is the prevalence of boreal plankton taxa within Arctic plankton communities. These data will be of value in supporting studies assessing the impacts of climate change on the structure and function of polar pelagic systems.

Cesium-137 and 137Cs/133Cs atom ratios in marine zooplankton off the east coast of Japan during 2012–2020 following the Fukushima Dai-ichi nuclear power plant accident

We measured the concentrations of cesium isotopes (133Cs, 134Cs, and 137Cs) in zooplankton samples collected in waters off the east coast of Japan from May 2015 to June 2020. By combining these data with those obtained previously from May 2012 to February 2015, we evaluated the long-term impacts of the Fukushima Dai-ichi Nuclear Power Plant accident on marine zooplankton. Relatively high 137Cs concentrations in zooplankton, exceeding 10 Bq/kg-dry weight, were sporadically observed until June 2016, regardless of year or station. After May–June 2017, 137Cs concentrations decreased to below 1 Bq/kg-dry at most stations, and by May 2020, concentrations were below 0.5 Bq/kg-dry except those off Fukushima Prefecture. Since the accident, the 137Cs/133Cs atom ratios of zooplankton samples were higher than those of ambient seawater until 2019, but in May–June 2020 the ratios matched those of seawater except off Fukushima Prefecture. Highly radioactive particles were not detected in zooplankton samples by autoradiography using imaging plates after May–June 2017, although they were before. Therefore, the persistence of elevated 137Cs/133Cs ratios in zooplankton relative to seawater for nine years after the accident was probably due to the incorporation of highly radioactive particles (cesium-bearing particles or clay-mineral aggregates with highly adsorbed radiocesium) onto/into zooplankton for several years after the accident. However, since at least May–June 2017, these elevated ratios have likely been caused by small highly radioactive particles (or larger particles disaggregated into small pieces) entering the ocean from land via rivers or directly discharged from the Fukushima Nuclear Power Plant. Microplastics enriched with radiocesium with higher 137Cs/133Cs ratios than seawater may have also contributed 137Cs to the zooplankton.

Vampyrophrya pelagica (Chatton and Lwoff 1930), an apostome ciliate infectious on calanoid copepod from the Northeastern Arabian Sea

BackgroundZooplankton provides a dynamic habitat to various kinds of epibionts in the marine ecosystem and also forms a source of food and nutrients to various parasites and parasitoids. The study was conducted to identify the association of ciliates with calanoid copepod of Northeastern Arabian Sea. Zooplankton samples collected were analysed under stereomicroscope for any kind of ciliate attachments. The infective stage and major characteristics of the ciliates were discussed. The present observation is the first report of apostome ciliate Vampyrophrya pelagica on calanoid copepod Bestiolina similis from the open ocean waters off Tarapur, Northeastern Arabian Sea, during the early spring intermonsoon season and also a new host record for the ciliate.ResultsAnalysis of ~ 2530 copepod revealed the presence of 12 copepod specimens infested with apostome ciliate Vampyrophrya pelagica. All the host copepod, identified as Bestiolina similis, were females. Approximately 50–60 ciliates occupied the host endocuticular region. V. pelagica was represented by fully grown trophont stage characterized by the presence of a large food vacuole surrounded by a thin layer of cytoplasm with numerous lipid bodies.ConclusionThe study establishes a new host record, calanoid copepod B. similis for V. pelagica. The report is the first of its kind from the Indian waters and extends the biogeographic boundary of the apostome ciliate.

Intensive marine finfish aquaculture impacts community structure and metal bioaccumulation in meso-zooplankton

Commercial aquaculture has a profound impact on coastal marine environments. Here, we investigate the spatial impact of intensive commercial finfish aquaculture on local meso-zooplankton communities and the bioaccumulation of aquaculturally-derived metals (and other elements) within zooplankton samples in the Vourlias Bay, Greece. The results indicate alterations to zooplankton community composition correlate with increased eutrophic compound concentrations in the water column in closer proximity to aquaculture stations (100–300 m from fish cages). During the summer sampling, higher concentrations of accumulated metals within zooplankton samples were found at reference stations furthest from fish cages (>1000 m). During the winter sampling, however, spatial differences in accumulated metal concentrations were limited. We suggest metals are rapidly accumulated at lower trophic levels near aquaculture stations and are then dispersed to greater distances while ascending the trophic chain. This research provides good evidence for future investigations into zooplankton as an environmental impact bioindicator for aquaculture.

Extensive Carbon Contribution of Inundated Terrestrial Plants to Zooplankton Biomass in a Eutrophic Lake.

Organic carbon derived from terrestrial plants contributes to aquatic consumers, e.g., zooplankton in lakes. The degree of the contribution depends on the availability of terrestrial organic carbon in lake organic pool and the transfer efficiency of the carbon. Terrestrial organic carbon is poor-quality food for zooplankton with a mismatch of nutrition content and was incorporated to zooplankton with much lower efficiency than phytoplankton. Contributions of terrestrial carbon to zooplankton generally decrease with an increase in phytoplankton production, indicating a preferential incorporation of phytoplankton in previous investigations. However, in eutrophic lakes, the dominating cyanobacteria were of poor quality and incorporated to consumers inefficiently too. In that case, zooplankton in eutrophic wetlands, where cyanobacteria dominate the phytoplankton production and massive terrestrial plants are inundated, may not preferentially incorporate poor food-quality phytoplankton resource to their biomass. Therefore, we hypothesize that carbon contributions of terrestrial vegetation to zooplankton and to lake particulate organic pool should be similar in such aquatic ecosystems. We tested this hypothesis by sampling zooplankton and carbon sources in Ming Lake (Jinan University Campus, southern China) which was overgrown by terrestrial plants after drying and re-flooded. After 60days of observations at weekly (or biweekly) intervals, applying stable carbon (13C), nitrogen (15N), and hydrogen (2H) isotopic analysis and a stable isotope mixing model, we estimated the occurrence of extensive carbon contribution (≥ 50%) of flooded terrestrial plants to cladocerans and copepods. Contribution of inundated terrestrial plants to cladocerans was similar to that to lake particulate organic pool. Thus, our study quantified the role of terrestrial carbon in eutrophic wetlands, enhancing our understanding of cross-ecosystem interactions in food webs with an emphasis on the resource quality.

On ten high-mountain lakes of Corsica island (France) – A delayed report of an investigation in summer 1970

In August 1970, ten mountain lakes on the island of Corsica (France) were studied. Temperatures and oxygen concentrations were measured as depth profiles, the shading effects of surrounding topographic elevations as skyline values compared to corresponding daily solar elevations. Turbidity and approximate underwater light spectra were evaluated using six color Secchi discs. Alkalinity and electrical conductivity values showed extremely soft water in the lakes. The influence of altitude on lake surface temperatures was analysed, compared to lakes in the Caucasus region and could be separated from the influence of topographical sun shading. Six copepod species were found in zooplankton samples and compared to meta-communities in lakes in other mountain regions.

Distribution and ecological risk of metals in an urban natural protected area in the Riviera Maya, Mexico.

Urbanization can negatively impact natural protected areas near or surrounded by cities, and such impacts include untreated wastewater discharge, leachates from dumpsters, e-waste, and road dust. In this research, we show that not only large cities with industry are prone to be polluted, but also young touristic cities with high population increase rate can suffer from urban contamination. We evaluated metal pollution in a natural protected area within a 50-year-old city without conventional industry that was likely contaminated by the urban sprawl around the protected area. We tested water, zooplankton, sediment and plant samples for metallic elements to evaluate their bioaccumulation in zooplankton, enrichment factors and geoaccumulation index values in sediments, and translocation factors in plants. Finally, we evaluated the ecological risk due to metal contamination. Metals at levels above our detection limit (20µg/L) were not found in the water and zooplankton samples. The sediments and plants in the storm drain section of the protected area had a greater concentration of metals and wastewater indicators (coliforms) than those in the rest of the lagoon. Moreover, signs of Al, Cu, Ni, Zn, Cr, Pb, and Ti contamination were found in the plant tissues. We estimated that the ecological risk of this natural protected area surrounded by the city of Cancun (Mexico) ranged from mild to strong, with Zn being the metal of most concern. The results highlight that young touristic cities around the world will endure contamination from urban sources; signs or early warnings of contamination must be identified to prevent and resolve such issues.

Diversity of zooplankton in Kadalundi-Vallikunnu Community Reserve, North Kerala, India

Zooplankton samples collected from ten stations covering the entire stretch of the Kadalundi-Vallikunnu CommunityReserve, Kerala, south India, for a period from July 2018 to June 2019 were studied. Twenty eight groups of zooplankton viz. copepods, foraminifera, medusae, chaetognaths, siphonophores, ctenophores, ostracods, cladocera, Lucifer sp., amphipods, isopods, appendicularia, Balanus nauplii, cyphonautes larvae, polychaete larvae, echinoderm larvae, ephyra larvae, brachiopod larvae, alima larvae of squilla, aquatic insect larvae, prawn larvae, crab zoea, crab megalopa larvae, bivalve larvae, pteropods, gastropod larvae, fish eggs and fish larvae were recorded. Among these, copepods formed the major portion of 43%. An average of 18330 nos. per 100 m3 was noticed from the study area. The maximum and minimum density of zooplankton was observed at Station 1 and 10 respectively and a decreasing trend in abundance was recorded from barmouth towards upstream stations. Seasonal studies indicated a maximum of 52% during pre-monsoon, followed by 36% during post-monsoon and a minimum of 12% during monsoon. Different indices of diversity, dominance plot, dendrogram and Multi Dimensional Scaling (MDS) plot are presented and discussed. Keywords: Biodiversity, Estuary, PRIMER, Primary consumers, Seasonality

TrophicCS: Spatialized trophic data of the Celtic Sea continental shelf food web.

Understanding the dynamics of species interactions for food (prey-predator, competition for resources) and the functioning of trophic networks (dependence on trophic pathways, food chain flows, etc.) has become a thriving ecological research field in recent decades. This empirical knowledge is then used to develop population and ecosystem modeling approaches to support ecosystem-based management. The TrophicCS data set offers spatialized trophic information on a large spatial scale (the entire Celtic Sea continental shelf and upper slope) for a wide range of species. It combines ingested prey (gut content analysis) and a more integrated indicator of food sources (stable isotope analysis). A total of 1337 samples of large epifaunal invertebrates (bivalve mollusks and decapod crustaceans), zooplankton, fish, and cephalopods, corresponding to 111 taxa (94% determined at the species level), were collected and analyzed for stable isotope analysis of their carbon and nitrogen content. Samples were collected between 2014 and 2016, mostly during the month of November and between 57 and 516 m depth. Sample size varied between taxa (from 1 to 52), with 98 taxa having at least three samples. The gut contents of 1027 fish belonging to 10 commercially important species: black anglerfish (Lophius budegassa), white anglerfish (Lophius piscatorius), blue whiting (Micromesistius poutassou), cod (Gadus morhua), haddock (Melanogrammus aeglefinus), hake (Merluccius merluccius), megrim (Lepidorhombus whiffiagonis), plaice (Pleuronectes platessa), sole (Solea solea), and whiting (Merlangius merlangus) were analyzed. Sampling occurred in November 2014 and 2015. The gut content data set contains the occurrence of prey in gut, identified to the lowest taxonomic level possible. No prey were assigned for 274 empty gut contents. To consider potential ontogenetic diet changes, a large size range was sampled for each species. The TrophicCS data set was used to improve understanding of trophic relationships and ecosystem functioning in the Celtic Sea. Data are released under a CC-BY-NC-SA license, and please cite this paper when reusing the data.

Relationship between physicochemical parameters and the abundance of zooplankton in Lake Mweru-Wantipa, Zambia

Abstract. Anamunda A, Lamtane HA. 2022. Relationship between physicochemical parameters and the abundance of zooplankton in Lake Mweru-Wantipa, Zambia. Intl J Bonorowo Wetlands 12: 33-40. This study aimed to assess the abundance of zooplankton and their relationship with physicochemical parameters within Lake Mweru-Wantipa, Zambia. A National Park borders the lake on one side and settlements on the other, so four sampling stations were selected, two on each side of the lake. Five physicochemical parameters, including temperature, turbidity, salinity, pH, and dissolved oxygen, were measured monthly using portable instruments concurrently with a collection of duplet zooplankton samples at each sampling point at depths between 0.1m and 0.5m. All physicochemical parameters were significantly different between the two sites (p<0.05) apart from temperature and pH. A total of 13 genera of zooplankton were identified, belonging to four groups, namely, rotifers, cladoceran, copepods, and ostracods. The cladoceran had the highest number of species (6), followed by copepods (4) in both sites. However, the copepods had the largest contribution in abundance in both sites. The diversity was high in settlement areas, but the National Park had higher species richness. There was a significant difference in species diversity between the two sites (t=3.96; p=0.001). The most abundant group was the cyclopoid on both sides of the lake, followed by the Moina on the settlement site and the Daphnia sp. on the National Park site. The densities of Molina, Simocephalus, Ceriodaphinia, and Cypris were significantly different between the two sites (p<0.05). Except for copepods, all groups were significantly different between the two sites (p<0.05). Generally, the total zooplankton density was not significantly different between the two sites (t=0.73; p=0.06). The results showed that the zooplankton abundance was influenced by turbidity in settlement areas and pH in National park areas.

Detection and monitoring of invertebrate non-indigenous species through DNA metabarcoding in a recreational marina of the Northwest of Portugal

In marine and coastal ecosystems, the proliferation of non-indigenous species (NIS) is among the top causes of biodiversity loss. Thus, it is essential to prevent the entrance and proliferation of NIS by detecting their presence as early as possible at the most susceptible locations, such as ports and marinas. Molecular techniques, like DNA metabarcoding, may be faster and more effective in the early detection of NIS. Its high sensitivity allows the detection of species at any stage of their life cycle and when present at very low densities. However, the detection power can be affected by the methodologies employed through the DNA metabarcoding analytical chain. This study aimed to assess the seasonal effects, sampling method (hard and artificial substrates, zooplankton and eDNA) and genetic marker (COI and 18S) in the recovery of NIS through DNA metabarcoding. Sampling was conducted in 3 seasons (spring, autumn, and winter of 2020/2021) in the “Porto Atlântico” marina, which is located near a major commercial port of the North of Portugal (Leixões). Overall, 626 species were identified through DNA metabarcoding, with the dominance of Crustacea, Ascidiacea and Mollusca. The sampling method and season significantly affected the marine invertebrate species recorded, for both molecular markers, with a high proportion of species detected exclusively using one method (7 to 20%). Overall, 31 NIS were detected, 7 of which are considered invasive and 6 are presumed new records in mainland Portugal. Zooplankton sampling and winter were, respectively, the method and the season where the highest number of NIS was detected, but the maximum number was only attained when pooling the results from all sampling methods and seasons. Our study highlights that different sampling methods and genetic markers, over different seasons, are needed to detect NIS in marine habitats, since the number of species shared by these factors is low.