Estuarine zooplankton responses to flood pulses and a hypoxic blackwater event

Flood pulses in estuaries following storms and rainfall events, are short-lived but important moments for a range of ecosystem processes including the delivery of resources and promoting productivity. Conversely some flood pulses can lead to adverse outcomes such as poor water quality conditions. The aim of this study was to determine how zooplankton abundance and community composition responded to flood pulses and if they responded differently during a flood pulse that led to hypoxic conditions. To do this we conducted a two-year observational study in the Hunter River estuary, Australia, monitoring zooplankton communities monthly for a period that covered two major flood pulse events including one that caused widespread hypoxia and a major fish kill. The results showed zooplankton abundance was higher or no different following the 2012 flood when dissolved oxygen remained stable compared to pre-flood conditions. During the 2013 flood when hypoxia occurred the abundance of copepods, nauplii and rotifers were at their lowest for the study period. Zooplankton assemblages were not distinctly different following the 2012 flood pulse compared to the pre-flood period but were different during the hypoxic 2013 flood, though quickly returned to resemble pre-flood conditions in the proceeding months. The study provides useful insights in how zooplankton populations may respond to flood events and recover after hypoxic conditions in estuarine ecosystems.

Download Full-text

Quantitative assessment of ecological operation effects based on flood pulses and ecology-economic coupling model: a case study of Three Gorges Reservoir, China

Water Science & Technology Water Supply ◽

10.2166/ws.2021.306 ◽

2021 ◽

Author(s):

Jiqing Li ◽

Jing Huang ◽

Zhiming Xue ◽

Pengteng Liang ◽

Yueqiu Wu

Keyword(s):

Three Gorges Reservoir ◽

Simulation Method ◽

Coupling Model ◽

Flood Pulse ◽

Ecological Impacts ◽

Three Gorges ◽

River Ecosystem ◽

Random Simulation ◽

Flood Pulses

Abstract Flood pulses are closely related to river ecosystem health. Reservoirs bring many benefits to flood control, power generation, shipping etc., but their attenuation effects on runoff flood pulses should not be ignored. Ecological operation can effectively reduce some negative ecological impacts brought by the reservoir. However, the inability to quantitatively assess ecological effects hinders the promotion of ecological operation in reservoir management. To solve this problem, we proposed 11 flood pulse indicators (FPI), a random simulation method and an ecology-economy coupling model in this study. In addition, we used four major Chinese carps as indicator species and the Three Gorges Reservoir as a case study to test the role of flood pulses in improving the ecological operation effects of the reservoir from the fish protection perspective. The results show that: (1) FPI can be controlled by the reservoir and reflect the flood pulse characteristics of runoff. (2) Random simulation method guides managers to optimize the discharge and formulate eco-friendly operation schemes. (3) Ecology-economy coupling model helps managers analyze the relationship between ecological operation effects and economic benefits. A comprehensive assessment can improve the acceptance of ecological operation, which is conducive to the sustainable development of river ecosystem.

Download Full-text

Environmental drivers of a decline in a coastal zooplankton community

ICES Journal of Marine Science ◽

10.1093/icesjms/fsab177 ◽

2021 ◽

Author(s):

Seòna R Wells ◽

Eileen Bresnan ◽

Kathryn Cook ◽

Dafne Eerkes-Medrano ◽

Margarita Machairopoulou ◽

...

Keyword(s):

Zooplankton Community ◽

Water Masses ◽

Environmental Drivers ◽

High Temporal Resolution ◽

Monitoring Site ◽

Zooplankton Abundance ◽

Offshore Water ◽

Additive Mixed Models ◽

Zooplankton Communities

Abstract Major changes in North Atlantic zooplankton communities in recent decades have been linked to climate change but the roles of environmental drivers are often complex. High temporal resolution data is required to disentangle the natural seasonal drivers from additional sources of variability in highly heterogeneous marine systems. Here, physical and plankton abundance data spanning 2003–2017 from a weekly long-term monitoring site on the west coast of Scotland were used to investigate the cause of an increasing decline to approximately -80± 5% in annual average total zooplankton abundance from 2011 to 2017. Generalized additive mixed models (GAMMs), with an autoregressive correlation structure, were used to examine seasonal and inter-annual trends in zooplankton abundance and their relationship with environmental variables. Substantial declines were detected across all dominant taxa, with ∼ 30–70% of the declines in abundance explained by a concurrent negative trend in salinity, alongside the seasonal cycle, with the additional significance of food availability found for some taxa. Temperature was found to drive seasonal variation but not the long-term trends in the zooplankton community. The reduction in salinity had the largest effect on several important taxa. Salinity changes could partly be explained by locally higher freshwater run-off driven by precipitation as well as potential links to changes in offshore water masses. The results highlight that changes in salinity, caused by either freshwater input (expected from climate predictions) or fresher offshore water masses, may adversely impact coastal zooplankton communities and the predators that depend on them.

Download Full-text

Biotic vs. abiotic forcing on plankton assemblages varies with season and size class in a large temperate estuary

Journal of Plankton Research ◽

10.1093/plankt/fbaa010 ◽

2020 ◽

Vol 42 (2) ◽

pp. 221-237 ◽

Cited By ~ 1

Author(s):

Gretchen Rollwagen-Bollens ◽

Stephen Bollens ◽

Eric Dexter ◽

Jeffery Cordell

Keyword(s):

Community Dynamics ◽

Abiotic Factors ◽

River Estuary ◽

Multiple Time Scales ◽

Nutrient Concentrations ◽

Winter Period ◽

Zooplankton Abundance ◽

Multiple Time ◽

P Availability ◽

Lower Estuary

Abstract Large river estuaries experience multiple anthropogenic stressors. Understanding plankton community dynamics in these estuaries provides insights into the patterns of natural variability and effects of human activity. We undertook a 2-year study in the Columbia River Estuary to assess the potential impacts of abiotic and biotic factors on planktonic community structure over multiple time scales. We measured microplankton and zooplankton abundance, biomass and composition monthly, concurrent with measurements of chlorophyll a, nutrient concentrations, temperature and salinity, from a dock in the lower estuary. We then statistically assessed the associations among the abundances of planktonic groups and environmental and biological factors. During the late spring high flow period of both years, the lower estuary was dominated by freshwater and low salinity-adapted planktonic taxa, and zooplankton grazers were more strongly associated with the autotroph-dominated microplankton assemblage than abiotic factors. During the early winter period of higher salinity and lower flow, nutrient (P) availability exerted a strong influence on microplankton taxa, while only temperature and upwelling strength were associated with the zooplankton assemblage. Our results indicate that the relative influence of biotic (grazers) and abiotic (salinity, flow, nutrients and upwelling) factors varies seasonally and inter-annually, and among different size classes in the estuarine food web.

Download Full-text

Zooplankton variation in relation to hydrology in an enclosed hypoxic bay (Amvrakikos Gulf, Greece)

Mediterranean Marine Science ◽

10.12681/mms.695 ◽

2014 ◽

Vol 15 (3) ◽

pp. 554 ◽

Cited By ~ 4

Author(s):

G. KEHAYIAS ◽

M. APOSPORIS

Keyword(s):

Vertical Mixing ◽

Zooplankton Community ◽

Oxygen Depletion ◽

Zooplankton Abundance ◽

Hypoxic Conditions ◽

Bivalve Larvae ◽

Coastal Embayment ◽

Short Period ◽

Water Stratification ◽

Hydrological Feature

This study investigated the temporal and spatial variation of the zooplankton community of a hypoxic coastal embayment (Amvrakikos Gulf, western Greece) in relation to hydrological characteristics during an annual cycle. The main hydrological feature was the prolonged water stratification, which determined hypoxic conditions in the deeper layers that became anoxic close to the bottom in September, while vertical mixing occurred for a very short period (October-November). The total zooplankton abundance fluctuated between 44.6 and 159.7 ind l-1. Fourteen groups were recorded, among which copepods dominated accounting on average for 86.4 %. Most of the groups presented higher abundance values in winter and spring when increased chlorophyll-α concentrations were found. Oxygen depletion affects the vertical distribution of most zooplankton groups and the vertical habitat partitioning between copepod orders and their ontogenetic stages. Several taxa were recorded even in the deep, anoxic layers, but only the polychaete larvae increased in abundance with depth. Calanoids, appendicularians and bivalve larvae presented eastward decrease of abundance in the deepest layers following the same pattern of oxygen decrease. Notwithstanding hypoxic conditions in its deepest layers, Amvrakikos Gulf was accounted for a mesotrophic ecosystem, with the nutrient concentration being lower than in the past. Several biotic elements indicate that the gulf is in a transitional phase towards a better quality state and these results reinforce the need for consistent monitoring of this ecosystem.

Download Full-text

Modelling of Water Exchange in an Estuary

Hydrology Research ◽

10.2166/nh.1978.0005 ◽

1978 ◽

Vol 9 (1) ◽

pp. 43-56

Author(s):

Juha Sarkkula ◽

Markku Virtanen

Keyword(s):

Cross Section ◽

Water Exchange ◽

River Estuary ◽

Research Area ◽

Multiple Correlation ◽

The Road ◽

Dry Spell ◽

Gulf Of Bothnia ◽

Flood Period ◽

Sea Level Fluctuation

A two-dimensional horizontal hydrodynamical model has been used to estimate the changes that a harbour road will cause in the water exchange of an estuary. The research area has been the Kokemäenjoki river estuary on the coast of the Gulf of Bothnia in western Finland. The numerical model has been verified on the basis of a regression model describing the water exchange of the estuary at present with a multiple correlation squared of 0.9. The factors having an influence on the water exchange are the wind, the sea level fluctuation and the river discharge. The changes in the water exchange have been considered during a dry spell, a flood period and an average year with three different cross-section areas of the road line. The accuracy and reliability of the estimation are found to be very satisfactory.

Download Full-text

8. The Effect of Bythotrephes Longimanus on the Size Structure of Zooplankton Communities in the Muskoka Region, Ontario

Inquiry@Queen's Undergraduate Research Conference Proceedings ◽

10.24908/iqurcp.7869 ◽

2017 ◽

Author(s):

Johanna Pokorny

Keyword(s):

Large Scale ◽

Size Structure ◽

Scale Effects ◽

Regional Scale ◽

Zooplankton Community ◽

Zooplankton Abundance ◽

Bythotrephes Longimanus ◽

Zooplankton Species ◽

Community Size ◽

Zooplankton Communities

Invasive species are considered the greatest threat to aquatic ecosystem biodiversity. Bythotrephes longimanus, an exotic zooplankton species introduced to North America in the 1980s, is threatening the structure of indigenous aquatic ecosystems as it continues to invade inland Ontario lakes. As a predacious zooplankton species, B. longimanus has been shown to decrease zooplankton abundance, species richness and shift zooplankton community size structure in invaded lakes. However, much of the previous research concerning the predatory effects of B. longimanus has been on surveys of a small number of lakes or has been in controlled mesocosm or lab-based experiments. This study examines the effects of B. longimanus on the zooplankton community using size-structure characterizations (grouping individuals from the community based on size) as community measures for 311 lakes in the Muskoka Region, a highly invaded watershed in Southern Ontario. More specifically, the study explores the size-spectra of invaded versus uninvaded lakes, with reference to an array of environmental lake characteristics (water chemistry, lake morphometry,etc.), and the relevance of B. longimanus activity on the regional scale. By using such a large-scale survey we will be able to appreciate regional-scale effects, as well as encompass the multiple and more indirect trophic interactions that B. longimanus is likely having with the entire aquatic community. (Funding: NSERC & CAISN.)

Download Full-text

Influence of the flood pulse on the reproduction of Tocantinsia piresi (Miranda Ribeiro) and Auchenipterus nuchalis (Spix & Agassiz) (Auchenipteridae) of the middle Xingu River, Brazil

Brazilian Journal of Biology ◽

10.1590/1519-6984.00114bm ◽

2015 ◽

Vol 75 (3 suppl 1) ◽

pp. 158-167 ◽

Cited By ~ 3

Author(s):

TMS. Freitas ◽

BS. Prudente ◽

VA. Oliveira ◽

MNC. Oliveira ◽

EG. Prata ◽

...

Keyword(s):

Sex Ratio ◽

Condition Factor ◽

Gonadosomatic Index ◽

Flood Pulse ◽

Allometric Growth ◽

Xingu River ◽

Ratio Size ◽

Flood Period ◽

First Maturity ◽

Size At First Maturity

Abstract This study investigates the influence of the flood pulse on the reproductive biology of the auchenipterids Tocantisia piresi (Miranda Ribeiro, 1920) and Auchenipterus nuchalis (Spix & Agassiz, 1829) from the middle Xingu River in the Brazilian state of Pará. The specimens were collected every three months between April, 2012, and January, 2014, covering four distinct periods (flood, ebb, dry, and filling). The sex ratio, size at first maturity, gonadosomatic index, and condition factor were analysed in the two species, and evaluated in the context of the different hydrological periods. A total of 897 specimens of T. piresi were collected, of which 467 were female, and 430 males, and 383 A. nuchalis (286 females and 97 males). In T. piresi, the sex ratio was biased only in the filling and ebb periods, whereas in A. nuchalis, it departed significantly from the expected ratio of 1:1 in all periods, with a predominance of females. The female T. piresi mature at a smaller size than the males, with the opposite of the pattern being recorded in A. nuchalis. In T. piresi, the breeding peak was observed during the low water periods, whereas in A. nuchalis, the peak was recorded in the flood periods. Male and female T. piresi presented similar positively allometric growth rates, whereas in A. nuchalis, growth was negatively allometric, but rates were different between genders. A higher condition factor was recorded in the females of both species during the ebb period. Overall, the results of this study reveals distinct flood pulse effects on the reproductive parameters of the two auchenipterid species studied; for A. nuchalis the spawning seems to happen at the flood period and for T. piresi at the dry season of the middle Xingu River.

Download Full-text

Rainfall events and downstream drift of microcrustacean zooplankton in a Newfoundland boreal stream

Canadian Journal of Zoology ◽

10.1139/z02-077 ◽

2002 ◽

Vol 80 (6) ◽

pp. 997-1003 ◽

Cited By ~ 22

Author(s):

Christine E Campbell

Keyword(s):

Invertebrate Drift ◽

Zooplankton Abundance ◽

Strongly Correlated ◽

Upstream Site ◽

Rainfall Events ◽

Flushing Rate ◽

Stream Discharge ◽

Stream Productivity ◽

High Precipitation ◽

Zooplankton Drift

While rainfall events may lead to flushing of zooplankton from lakes, with implications for stream productivity near lake outlets, consideration also needs to be given to zooplankton transported farther downstream. To evaluate such downstream transport, daytime invertebrate drift, stream discharge, and rainfall events were monitored over 4 summers in Cook's Brook, Newfoundland, at a downstream site 1.0 km below the outlet of Big Cook's Pond and an upstream site 1.0 km upstream of the pond. Microcrustacean zooplankton were abundant in some downstream samples; high percent zooplankton abundance (8794%) corresponded to the highest total invertebrate drift densities. Percent zooplankton in downstream drift was strongly correlated with recent rainfall (rS = 0.815, p = 0.025) and stream discharge (rS = 0.964, p = 0.001). The majority of microcrustaceans in the drift were planktonic cladocerans and copepods, the species composition being similar to that in Big Cook's Pond. No zooplankton were ever collected from the upstream site. Ephemeroptera, Diptera, Trichoptera, and Ostracoda were abundant in most drift samples. Zooplankton drift (mean = 0.17 individuals/m3) in Cook's Brook appears to be catastrophic drift, with high precipitation rates and resultant increased flushing rate in Big Cook's Pond leading to "washout" of microcrustaceans 1 km downstream.

Download Full-text

Metacommunity Concepts Provide New Insights in Explaining Zooplankton Spatial Patterns within Large Floodplain Systems

Water ◽

10.3390/w14010093 ◽

2022 ◽

Vol 14 (1) ◽

pp. 93

Author(s):

Baogui Liu ◽

Chuanqiao Zhou ◽

Lilin Zheng ◽

Haixin Duan ◽

Ying Chen ◽

...

Keyword(s):

Water Level ◽

Spatial Patterns ◽

Zooplankton Community ◽

High Water ◽

Flood Pulse ◽

Floodplain Management ◽

Zooplankton Community Structure ◽

Temporal Aspects ◽

Explained Variance ◽

Zooplankton Communities

Flood pulse related physical variables (FLOOD) can affect zooplankton community structure through local factors directly and can also influence through regional dispersal factors of metacommunity concepts indirectly. Therefore, we infer that spatial patterns of zooplankton communities could be related to metacommunity concepts and their importance may depend on the size of the aquatic/terrestrial transition zone (ATTZ). Herein, we explored the relative importance of limnological (LIMNO) and FLOOD variables in zooplankton community by analyzing data from 272 sites across three floodplain lakes in the middle reaches of the Yangtze River. Our results showed that the variation in the zooplankton community can be well explained by the LIMNO and FLOOD variables in all of the lakes under the low water level season. However, during the high water level season, neither LIMNO nor FLOOD can explain the spatial variances of zooplankton. Therefore, our results indicated that testing biogeographical theories and macroecological laws using zooplankton should consider temporal aspects of flood pulse. Furthermore, we noted that the number of explained variance by local variables is negatively correlated with the size of the ATTZ. Metacommunity concepts provide complementary insights in explaining zooplankton spatial patterns within large floodplain systems, which also provide a theoretical basis for ATTZ protection in floodplain management.

Download Full-text

Zooplankton communities in the Drake Passage through environmental boundaries: a snapshot of 2010, early spring

PeerJ ◽

10.7717/peerj.7994 ◽

2019 ◽

Vol 7 ◽

pp. e7994

Author(s):

Andrey A. Vedenin ◽

Eteri I. Musaeva ◽

Daria N. Zasko ◽

Alexander L. Vereshchaka

Keyword(s):

Spatial Distribution ◽

Environmental Factors ◽

Chlorophyll Concentration ◽

Environmental Parameters ◽

Drake Passage ◽

Early Spring ◽

Zooplankton Abundance ◽

Depth Range ◽

Zooplankton Structure ◽

Zooplankton Communities

Background Spatial distribution of zooplankton communities influenced by various environmental factors is always important for understanding pelagic ecosystems. The area of the Drake Passage (Southern Ocean) is of particular interest owing to the high spatial and temporal variability of hydrological parameters affecting marine fauna. This study provides a survey of zooplankton composition and spatial distribution along a transect in the Drake Passage sampled during the 31th Cruise of RV “Akademik Sergey Vavilov” in November, 2010. The main aim was to trace the main regularities in spatial zooplankton structure and its relationships with the environmental parameters. Methodology A total of 43 vertical hauls from the surface to 1,000 m depth were made at 13 stations using the Juday plankton net. 60 taxa were recorded, abundance and biomass of each were assessed. Environmental parameters including temperature, salinity, depth, horizontal distance between stations and surface chlorophyll concentration were tested as environmental factors possibly explaining plankton distribution. Results Higher zooplankton abundance and biomass with lower diversity were observed near the Polar Front. Cluster analysis revealed five different groups of zooplankton samples, four of which were arranged mostly by depth. Along the transect within the 1,000 m depth range, the qualitative taxonomical composition differed significantly with depth and to some extent differed also among horizontal hydrological regimes, while the quantitative structure of the communities (abundance of taxa) was mainly determined by depth. Plankton assemblages within the upper 300-m layer depended on hydrological fronts. Abundance of dominant taxa as well as total zooplankton abundance showed a clear correlation with depth, salinity and surface chlorophyll concentration. Some taxa also showed correlations with temperature and latitude. Between the stations the similarity in zooplankton structure was clearly dependent on the distance among them which indicates an importance of latitudinal gradient. Surface chlorophyll concentration was not correlated with zooplankton biomass, which can be explained by the uncompleted seasonal migrations of zooplankton from deeper waters in early spring.

Download Full-text