Responses of mesozooplankton communities to different anthropogenic activities in a subtropical semi-enclosed bay

Abstract

To evaluate the effects of different anthropogenic activities on zooplankton and the pelagic ecosystem, we conducted seasonal cruises in 2010 to assess spatial heterogeneity among the mesozooplankton communities of Xiangshan Bay, a subtropical semi-enclosed bay in China. The evaluation included five different areas: a kelp farm, an oyster farm, a fish farm, the thermal discharge area of a power plant, and an artificial reef, and we aimed to identify whether anthropogenic activities dominated spatial variation in the mesozooplankton communities. The results demonstrated clear spatial heterogeneity among the mesozooplankton communities of the studied areas, dominantly driven by natural hydrographic properties, except in the area near the thermal discharge outlet of the power station. In the outlet area, thermal shock caused by the discharge influenced the mesozooplankton community by decreasing abundance and biomass throughout the four seasons, even causing a shift in the dominant species near the outlet during summer from Acartia pacifica to eurythermal and warm water taxa. Unique features of the mesozooplankton community in the oyster farm may be due to the combined effects of oyster culture and the natural environment in the branch harbour. However, kelp and fish culture, and the construction of an artificial reef did not exert any obvious influence on the mesozooplankton communities up to 2010, probably because of the small scale of the aquaculture and a time lag in the rehabilitation effects of the artificial reef. Thus, our results suggested that the dominant factors influencing spatial variations of mesozooplankton communities in Xiangshan Bay were still the natural hydrographic properties, but the thermal discharge was an anthropogenic activity that changed the pelagic ecosystem, and should be supervised.

The empirical evidence for the social-ecological impacts of seaweed farming

“…sites [117][118][119][120][121][122][123], while others report no statistically clear effect [98,111,124] and one records a decrease in pH [125]. Sediments underneath and near seaweed farms undergo various shifts including an increase in the acid volatile sulfide content of the benthos [126], a decrease in bacterial production and nitrogen content in sediments [127], a decrease in organic matter content [128] and a redistribution of fine and coarse grained sediments [114,129,130], with many of these changes being associated with clear changes in faunal communities [114,126,127,130].…”

“…Mobile herbivorous finfish stand the most to gain from the proliferation of seaweed farms, likely due to the increase in grazing opportunities and habitat [103][104][105][106]. But the benefits for planktonic communities, including improved community diversity and stability, were heavily dependent on the seaweed species being cultivated [99,[107][108][109][110][111][112]; and outcomes were more frequently negative for benthic invertebrates and seagrass whom particularly suffered from habitat disruption due to 'off-the-bottom' farming techniques [113][114][115][116].…”

Anthropogenic pollutant-driven geographical distribution of mesozooplankton communities in estuarine areas of the Bohai Sea, China

“…The crucial role in marine food webs indicates that decline in biodiversity of zooplankton could decrease the survival rates of higher trophic organisms such as fish 20 , and eventually pose far-reaching consequences for the marine food webs 21 . Moreover, zooplankton assemblages consist of species highly sensitive to environmental pollutants such as nutrients and heavy metals, and their variation could be attributed to different levels of pollution in marine systems, such as estuarine systems 19,22,23 and coastal systems 24,25 , also making them good indicators to explore ecological effects of anthropogenic pollutants. Available studies mainly focused on ecological effects of environmental variables and hydrological processes on zooplankton community structure 26,27 .…”

Editorial

“…In their review, David & Loveday (2018) define and highlight the potential importance of cryptic dispersal in determination of marine connectivity and hence the design of Marine Protected Areas. The effects of anthropogenic activities in a subtropical bay in China are explored by Du et al (2018). Insights are provided by a local fishing community into the small cetacean Pontopora blainvillei in southern Brazil and demonstrate the potential of combining traditional and scientific knowledge for species conservation (Zappes et al ., 2018).…”