Method for controlling <i>Aurelia </i>spp. blooms in harbors

Abstract

A method for controlling Aurelia spp. blooms in harbors includes: designing different sites at equal intervals in an area in spring, collecting ephyrae of Aurelia spp. with an I-type trawl net for zooplankton from bottom to surface, determining whether polyps of Aurelia spp. inhabit in the vicinity of the sites; seeking large floating substrates that the polyps attach to using scuba diving in the determined habitats of the polyps; dragging the substrates to a shore base and scraping off all organisms attached to bottom surfaces of the substrates in a physical manner, then air drying the substrates for 7 days or more; and applying an antifouling paint on the bottom surfaces of the dried substrates followed by drying, then returning the substrates back to their original sites in the sea to control the bloom of Aurelia spp. in the area.

Claims

1. A method for controlling an Aurelia spp. ephyrae bloom in a harbor, comprising: 1) designing less than or equal to ten different sites at equal intervals in spring, collecting Aurelia spp. ephyrae in the sea, determining whether Aurelia spp. ephyrae polyps inhabit in a vicinity of each of the different sites; 2) seeking large floating substrates that the polyps attach to by using scuba diving in the determined habitats of the polyps; 3) scraping off all organisms attached to bottom surfaces of the substrates in a physical manner, then air drying the substrates for more than 7 days; and 4) applying an antifouling paint to the bottom surfaces of the dried floating substrates followed by drying, then returning the substrates back to the different sites to control the bloom of Aurelia spp. ephyrae in the harbor.

2. The method of claim 1, wherein in step 1), less than or equal to ten different sites are designed at equal intervals in spring, the Aurelia spp. ephyrae are collected in the sea to determine whether the Aurelia spp. ephyrae polyps inhabit in the vicinity of each of the different sites; if Aurelia spp. ephyrae are found in a certain site, then the polyps habitat near the site; if no Aurelia spp. ephyrae are found in this certain site, a collecting area is further expanded till the Aurelia spp. ephyrae are found.

3. The method of claim 1, wherein in step 2), the Aurelia spp. ephyrae polyps are sought using scuba diving in an area with reduced water flow near the site where Aurelia spp. ephyrae are found.

4. The method of claim 1, wherein in step 3), all organisms attaching to the bottom surfaces of the floating substrates are completely scraped off in a physical manner, and then the scraped substrates are dried in the sun for more than 7 days.

5. The method of claim 1, wherein in step 4), 2-3 layers of the antifouling paint are applied to the bottom surfaces of the substrates, with a paint film of 50-75 m in thickness.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an image of an Aurelia coerulea ephyra.

(2) FIG. 2 shows an image of an Aurelia coerulea polyp.

(3) FIG. 3 shows the attachment of Aurelia spp. ephyrae polyps on the bottom surfaces of floating substrates; where A is a longitudinal diagram of the substrates, and B is a sectional view of the bottom surfaces of the substrates.

(4) FIG. 4 shows the Aurelia coerulea polyps attaching to the bottom surfaces of floating docks 1, 2, and 3.

(5) FIG. 5 shows the Aurelia coerulea polyps attaching to sessile organisms on the bottom of the floating docks 1, 2, and 3.

(6) FIG. 6 shows the attachment of sessile organisms on the bottom surface of the floating dock 1 in Middle Harbor (Qingdao, China) two years after the bottom surface has been painted with the antifouling paint.

(7) FIG. 7 shows the attachment of sessile organisms on the bottom surface of the floating dock 2 in Middle Harbor (Qingdao, China) one year after the bottom surface has not been painted with the antifouling paint.

(8) FIG. 8 shows the attachment of the Aurelia coerulea polyps on the bottom surface of the floating dock 3 without any treatment in June 2017.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

(9) The present invention is further described below with reference to the drawings and embodiments. The present invention is suitable for prevention and control of Aurelia spp. ephyrae blooms in an enclosed or semi-enclosed harbor or bay, and particularly for control of aggregations of Aurelia spp. ephyrae near the cooling water intakes of power plants and nuclear power plants, etc., which can significantly reduce the abundance of Aurelia spp. ephyrae in nearby waters, ensuring ecological health in the harbor and safety of cooling water source of coastal infrastructures. The present invention puts forward a new technique for the control of the Aurelia spp. ephyrae blooms in harbors.

EXAMPLE

(10) Taking the control of A. coerulea blooms in Middle Harbor, Port of Qingdao as an example, this embodiment is described in detail.

(11) (1) Seeking Out A. coerulea Ephyrae in the Harbor

(12) Massive A. coerulea appeared in the Middle Harbor, Port of Qingdao before 2014. In May 2014, five sites were designed, and Aurelia spp. ephyrae were collected with an I-type trawl net for zooplankton from the bottom of the harbor to the surface of the water. Massive A. coerulea ephyrae were collected in each site (3-10 ind/net, see FIG. 1). Thus, it was determined that a large number of A. coerulea polyps lived in this area. A. coerulea ephyra is mostly dark red or brown, with a cross-shaped central mouth, 8 pairs of rhopalial lappets and 8 rhopaliums. The rhopalial lappets are long and sharp without branches. Two rhopalial lappets get together at top. Nematocysts are dispersed on an umbrella surface in an irregular manner. The size of ephyrae is usually 2-3 mm.

(13) (2) Seeking Out A. coerulea Polyps by Using Scuba Diving

(14) In June 2014, A. coerulea polyps were sought in this area by scuba diving and massive A. coerulea polyps attaching to three floating docks 1, 2, and 3 were found with a density of 2339.42617.73 ind.Math.m.sup.2. Each floating dock was approximately 30 meters in length and 8 meters in width. The A. coerulea polyp (see FIG. 2) in an obconical shape is milky white with a relatively short stalk and 16 tentacles. On the surfaces of tentacles, nematocyst cluster is distributed with obvious protruding cilia. The diameter of polyp calyx is approximately 7001100 m. A. coerulea polyps settled upside down on the bottom surfaces (located 1.8 m below seawater surface) of the floating docks 1, 2, and 3, and distributed in patches (see FIG. 4). Lots of A. coerulea polyps also attached to the surfaces of some sessile organisms, such as ascidians and mussels that settled on the bottom surfaces of the floating docks (see FIG. 5).

(15) (3) Removing A. coerulea Polyps on the Bottom Surfaces of the Substrates

(16) In April, 2015 and 2016, the floating docks 1 and 2 were transported to Hongdao Shipyard, Jiaozhou Bay to completely scrape off A. coerulea polyps and other sessile organisms attaching to the bottom surfaces of the substrates. The floating dock 3 without treatment is provided as a control.

(17) (4) Applying an Antifouling Paint on the Bottom Surface of the Substrate

(18) The bottom surface of the floating dock 1 was dried in the sun for more than 7 days after the A. coerulea polyps and other sessile organisms were completely scraped off. Two layers of the modified chlorinated rubber antifouling paint, which was prepared by grinding and mixing chlorinated rubber, plasticizer, cuprous oxide, pigment, adjuvant, etc. (available from Yantai Federal Chemical Co., Ltd.), were applied on the bottom surfaces of the floating dock 1, with a paint film of 50-75 m in thickness. The bottom surface of the floating dock 2 was dried after the A. coerulea polyps were scraped off, but not painted with the antifouling paint, in order to demonstrate the inhibition of antifouling paint against the reattachment of A. coerulea planulae. Afterwards, the floating docks 1 and 2 were dried in the sun for one month and then returned back to the original sites in the sea.

(19) (5) Result

(20) It was demonstrated that the abundance of A. coerulea was decreased by 6681% from 2015 to 2018 in comparison to 2014 using the method of the invention. Two years after the bottom surface of floating dock 1 was painted with the antifouling paint, only a small amount of sessile organisms (FIG. 6) attached to the bottom surface, and the reattachment of A. coerulea polyps were not found there. However, a large number of sessile organisms had settled on the bottom surface of the floating dock 2 without the antifouling paint one year later (FIG. 7). Lots of A. coerulea polyps appeared in the second year, the density of which was 3512.312229.78 ind.Math.m.sup.2 in September, and more than in 2014. For the floating dock 3, massive A. coerulea polyps still settled on the empty space (left view in FIG. 8) and sessile organisms of the bottom surface (right view in FIG. 8), and the density was approximately 1700 ind.Math.m.sup.2 in June (see FIG. 8). The attachment of A. coerulea polyps and other sessile organisms can be effectively inhibited by painting the antifouling paint. The A. coerulea blooms in Middle Harbor (Qingdao) can be effectively prevented and controlled for a long time through regular maintenance once every four years.