Citation:

fmars.2019.00613

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Abstract:

Submarine groundwater discharge (SGD) is an ubiquitous pathway for nutrient rich freshwater to coastal ecosystems, demonstrably altering their hydrography, hydrochemistry, and primary productivity. Yet only little is known about the effects of fresh SGD on the fitness of higher trophic levels such as teleost fish. We examined feeding intensities, somatic conditions, and growth rates in juvenile grey demoiselle Chrysiptera glauca sampled between October 2017 and January 2018 in two contrasting tide pools in Mauritius: One strictly marine tide pool at Flic en Flac and another one influenced by the influx of SGD (Albion).

Specimens of C. glauca were caught with hand nets and immediately preserved in 30% ethanol/seawater solution. In the laboratory, fish were gradually transferred to 50% and 70% ethanol/freshwater solution. Further, fish were measured by standard length (SL, nearest mm), eviscerated, and weighed (EM, ± 0.001 g). Additionally, for each fish, stomach wet mass (SM, ± 0.001 g) was determined to calculate feeding intensity (FI): FI = SM × [E]^(-1) × 100. Further, a condition index (CI) was calculated for each individual by using b of the length-weight relationship: CI = EM × [SL]^(-b) × 100. We used the frequency of occurrence method for stomach content analysis (0: absence and 1: presence). Food organisms were identified to class level.

The sagittae and lapilli otoliths were dissected under a stereomicroscope, cleaned with deionized water, and stored dry in FEMA-cells (26 x 76 mm). Sagittae otoliths were weighed (± 0.001 mg). Lapilli otoliths were fixed on glass slides using 2-component adhesive (Araldite 2020/A and Araldite 2020/B) and ground sequentially on glass plates by silicon carbide (SiC) powder with grit sizes of 400 and 800. After polishing with waterproof silicon carbide grinding paper (grain size of 5 µm), otoliths in immersion oil were examined with a digital microscope (Keyence VHX-5000) using transmitted light at a magnification of 400x - 800x. With the digital microscope it was possible to compose depth-stitchings of different focus levels. Increment counts were conducted and OR was measured using ImageJ 1.49 (Rasband, WS, US National Institutes of Health, Bethesda, MD, http://imagej.nih.gov/ij/). Daily deposition of increments on the lapillus otolith has been validated in a number of species from this family and it was therefore assumed that increments on the lapilli were deposited daily. The increment closest to the core of the otolith was assumed to be formed at the day of hatching, as is the case in many other species from the family Pomacentridae. The number of increments was determined from 3 replicate increment counts. The settlement mark was identified as the first increment of a transition zone, characterized by a rapid narrowing in increment width.

Project(s):

Leibniz Centre for Tropical Marine Research (ZMT)

Coverage:

Median Latitude: -20.237639 * Median Longitude: 57.386616 * South-bound Latitude: -20.271555 * West-bound Longitude: 57.370448 * North-bound Latitude: -20.216441 * East-bound Longitude: 57.396721

Date/Time Start: 2017-10-19T00:00:00 * Date/Time End: 2018-01-29T00:00:00

Event(s):

Albion-01 * Latitude: -20.216441 * Longitude: 57.396721 * Date/Time: 2017-10-19T00:00:00 * Location: Mauritius * Method/Device: Hand net (HN)

Albion-02 * Latitude: -20.216441 * Longitude: 57.396721 * Date/Time: 2017-10-20T00:00:00 * Location: Mauritius * Method/Device: Hand net (HN)

Albion-03 * Latitude: -20.216441 * Longitude: 57.396721 * Date/Time: 2017-10-23T00:00:00 * Location: Mauritius * Method/Device: Hand net (HN)

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Comment
1	Event label	Event		Döring, Julian
2	Date/Time of event	Date/Time		Döring, Julian
3	Latitude of event	Latitude		Döring, Julian
4	Longitude of event	Longitude		Döring, Julian
5	Location	Location		Döring, Julian
6	Month	Month		Döring, Julian
7	Sample ID	Sample ID		Döring, Julian
8	Chrysiptera glauca, length	C. glauca l	mm	Döring, Julian
9	Chrysiptera glauca, wet mass	C. glauca wm	g	Döring, Julian
10	Comment	Comment		Döring, Julian	Gut empty (e) or full (f)
11	Chrysiptera glauca, stomach mass	C. glauca stomach m	g	Döring, Julian
12	Chrysiptera glauca, eviscerated mass	C. glauca eviscerated m	g	Döring, Julian
13	Chrysiptera glauca, gonad mass	C. glauca gonad m	g	Döring, Julian
14	Chrysiptera glauca, sagittae mass	C. glauca sagittae m	mg	Döring, Julian
15	Chrysiptera glauca, age	C. glauca age	days	Döring, Julian
16	Chrysiptera glauca, settlement age	C. glauca settlem age	days	Döring, Julian
17	Chrysiptera glauca, lapilus radius	C. glauca lapilus radius	µm	Döring, Julian
18	Condition index	CI		Döring, Julian
19	Feeding Intensity	Feed Intensity	#	Döring, Julian
20	Chlorophyceae	Chlorophyceae	#	Döring, Julian	0: absence, 1: presence
21	Anthozoa	Anthozoa	#	Döring, Julian	0: absence, 1: presence
22	Maxillopoda	Maxillopoda	#	Döring, Julian	0: absence, 1: presence
23	Gastropoda	Gastropoda	#	Döring, Julian	0: absence, 1: presence
24	Bivalvia	Bivalvia	#	Döring, Julian	0: absence, 1: presence
25	Arachnida	Arachnida	#	Döring, Julian	Arachnida/Insecta; 0: absence, 1: presence
26	Ichthyoplankton	Ichthyopl	#	Döring, Julian	0: absence, 1: presence
27	Plant detritus particles	Plant detrit particles	#	Döring, Julian	0: absence, 1: presence
28	Plastic particles	Plastic	#	Döring, Julian	0: absence, 1: presence

License:

Creative Commons Attribution 4.0 International (CC-BY-4.0)

Size:

2373 data points

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