Response of the fish assemblage to a saltwater barrier and paper mill effluent in the Lower Neches River (Texas) during drought

Figures & data

Figure 1. Top photo – Neches River channel upstream from the saltwater barrier; bottom photo – saltwater barrier on Lower Neches with gates in open position.

Figure 2. Seine (circles) and gillnet and water quality sites (both represented by triangles) during summer 2012. Differences in water quality (optics) above the saltwater barrier, below the saltwater barrier, and within the MeadWestvaco paper mill effluent delivery canal and rectangular collecting pond witin the Beaumont Unit are apparent in this GoogleEarth® image.

Table 1. Species % relative abundances for gillnet samples from the eight sites in the Neches River, Texas (F = freshwater, E = Estuarine, M = marine).

			Barrier period		Barrier location
Order	Family	Species	Open	Closed	Above	Below
Clupeiformes	Clupeidae	Skipjack shad, Alosa chrysochloris (E)	1.6	2.4	1.2	2.9
		Gulf menhaden, Brevoortia patronus (M)	4.3	10.8	4.3	10.5
		Gizzard shad, Dorosoma cepedianum (F)	1.2	5.1	2.9	3.5
		Threadfin shad, Dorosoma petenense (F)	0.2	4.5	4.5	0.2
Cypriniformes	Catostomidae	Smallmouth buffalo, Ictiobus bubalus (F)	2.4	4.3	1.2	5.5
	Cyprinidae	Blacktail shiner, Cyprinella venusta (F)	0	0.2	0.2	0
		Common carp, Cyprinus carpio (F)	0	0.2	0.2	0
Elopiformes	Elopidae	Ladyfish, Elops saurus (M)	0	0.2	0	0.2
Lepisosteiformes	Lepisosteidae	Alligator gar, Atractosteus spatula (F)	0.6	1.6	0	2.3
		Spotted gar, Lepisosteus oculatus (F)	3.5	8.4	2.5	9.4
		Longnose gar, Lepisosteus osseus (F)	4.7	5.7	6.2	4.3
Mugiliformes	Mugilidae	Striped mullet, Mugil cephalus (M)	2.0	2.2	0.2	4.2
Pleuronectiformes	Paralichthyidae	Southern flounder, Paralichthys lethostigma (M)	0.6	1.0	0	1.6
Perciformes	Centrarchidae	Flier, Centrarchus macropterus (F)	0.4	0.4	0	0.8
		Warmouth, Lepomis gulosus (F)	0.2	0.2	0	0.4
		Bluegill, Lepomis macrochirus (F)	0.6	1.0	0.4	1.2
		Longear sunfish, Lepomis megalotis (F)	0.6	0.2	0	0.8
		Redear sunfish, Lepomis microlophus (F)	1.8	0	0	1.8
		Spotted bass, Micropterus punctulatus (F)	0.6	0.8	0	1.4
		Largemouth bass, Micropterus salmoides (F)	0.8	1.6	0.2	2.3
		White crappie, Pomoxis annularis (F)	1.4	0.8	0.6	1.6
	Eleotridae	Fat sleeper, Dormiator maculatus (E)	0.2	0	0	0.2
	Moronidae	White bass, Morone chrysops (F)	0.4	0	0	0.4
		Yellow bass, Morone mississippiensis (F)	0.2	0.2	0	0.4
		Striped bass, Morone saxatilis (E)	0.2	0	0	0.2
	Sciaenidae	Freshwater drum, Aplodinotus grunniens (F)	2.2	2.2	1.8	2.7
		Sand weakfish, Cynoscion arenarius (M)	0	0.2	0	0.2
		Spot, Leiostomus xanthurus (M)	0	0.8	0	0.8
		Atlantic croaker, Micropogonias undulates (M)	0	0.4	0	0.4
		Red drum, Sciaenops ocellatus (M)	0.6	0.8	0	1.4
	Sparidae	Sheepshead, Archosargus probatocephalus (M)	0.2	0.6	0	0.8
Percopsiformes	Aphredoderidae	Pirate perch, Aphredoderus sayanus (F)	0.2	0.2	0.4	0
Pleuronectiformes	Achiridae	Hogchoker, Trinectes maculatus (M)	0.2	0	0	0.2
	Paralichthyidae	Bay whiff, Citharichthys spilopterus (M)	0.2	0	0	0.2
Siluriformes	Ariidae	Gafftopsail catfish, Bagre marinus (M)	0	0.4	0	0.2
	Ictaluridae	Blue catfish, Ictalurus furcatus (F)	1.8	6.1	2.9	5.1
		Channel catfish, Ictalurus punctatus (F)	0.6	1.0	0	1.6
		Flathead catfish, Pylodictis olivaris (F)	0.2	0	0.2	0

Table 2. Species % relative abundances for seine samples from the eight sites in the Neches River, Texas (F = predominantly freshwater, E = Estuarine, M = marine).

			Barrier period		Barrier location
Order	Family	Species	Open	Closed	Above	Below
Atheriniformes	Atherinopsidae	Brook silverside, Labidesthes sicculus (F)	<0.1	<0.1	<0.1	<0.1
		Inland silverside, Menidia beryllina (F)	3.7	1.8	0.1	5.5
Beloniformes	Belonidae	Atlantic needlefish, Strongylura marina (M)	<0.1	<0.1	<0.1	<0.1
Clupeiformes	Clupeidae	Gulf menhaden, Brevoortia patronus (M)	9.0	0.7	0.1	9.6
		Gizzard shad, Dorosoma cepedianum (F)	<0.1	<0.1	0.1	<0.1
		Threadfin shad, Dorosoma petenense (F)	4.9	0.2	0.2	5.0
	Engraulidae	Bay anchovy, Anchoa mitchilli (M)	45.0	18.5	3.2	60.3
Cypriniformes	Catostomidae	Smallmouth buffalo, Ictiobus bubalus (F)	<0.1	0	<0.1	0
	Cyprinidae	Red shiner, Cyprinella lutrensis (F)	0.1	<0.1	<0.1	<0.1
		Blacktail shiner, Cyprinella venusta (F)	4.3	1.5	4.6	1.3
		Ribbon shiner, Lythrurus fumeus (F)	0.2	0.1	0.1	0.1
		Shoal chub, Macrhybopsis hyostoma (F)	<0.1	0	<0.1	0
		Golden shiner, Notemigonus crysoleucas (F)	<0.1	0	0	<0.1
		Sabine shiner, Notropis sabinae (F)	<0.1	0	<0.1	0
		Weed shiner, Notropis texanus (F)	0.3	0.6	0.8	0.2
		Mimic shiner, Notropis volucellus (F)	1.4	<0.1	1.4	0
		Pugnose minnow, Opsopoeodus emiliae (F)	<0.1	<0.1	0.1	<0.1
		Bullhead minnow, Pimephalex vigilax (F)	1.9	0.9	2.7	<0.1
Cyprinodontiformes	Cyprinodontidae	Sheepshead minnow, Cyprinodon variegatus (E)	<0.1	0	0	<0.1
	Fundulidae	Gulf killifish, Fundulus grandis (E)	0.1	0	0	0.1
		Blackstripe topminnow, Fundulus notatus (F)	0.1	0.1	0.1	<0.1
		Rainwater killifish, Lucania parva (F)	0.1	<0.1	0	0.1
	Poeciliidae	Western mosquitofish, Gambusia affinis (F)	1.8	<0.1	<0.1	1.8
		Least killifish, Heterandria formosa (F)	<0.1	0	0	<0.1
		Sailfin molly, Poecilia latipinna (E)	0.1	0	0	0.1
Elopiformes	Elopidae	Ladyfish, Elops saurus (M)	0	<0.1	0	<0.1
Gasterosteiformes	Syngnathidae	Short-tailed pipefish, Microphis brachyurus (M)	<0.1	0	<0.1	0
		Gulf pipefish, Sygnathus scovelli (M)	<0.1	0	0	<0.1
Mugiliformes	Mugilidae	Striped mullet, Mugil cephalus (M)	0.1	0.1	<0.1	0.1
Perciformes	Centrarchidae	Flier, Centrarchus macropterus (F)	<0.1	0	<0.1	0
		Green sunfish, Lepomis cyanellus (F)	<0.1	0	0	<0.1
		Warmouth, Lepomis gulosus (F)	<0.1	0	<0.1	<0.1
		Bluegill, Lepomis macrochirus (F)	<0.1	<0.1	<0.1	<0.1
		Longear sunfish, Lepomis megalotis (F)	0.4	0.1	0.2	0.2
		Redear sunfish, Lepomis microlophus (F)	<0.1	0	<0.1	<0.1
		Redspotted sunfish, Lepomis miniatus (F)	<0.1	0	0	<0.1
		Spotted bass, Micropterus punctulatus (F)	0.1	<0.1	0.1	<0.1
		Largemouth bass, Micropterus salmoides (F)	0.1	<0.1	<0.1	0.1
		White crappie, Pomoxis annularis (F)	<0.1	0	<0.1	<0.1
	Gobiidae	Darter goby, Ctenogobius boleosoma (M)	0.1	<0.1	<0.1	0.1
		Freshwater goby, Ctenogobius shufeldti (E)	<0.1	0	0	<0.1
		Naked goby, Gobiosoma bosc (M)	<0.1	0	0	<0.1
	Moronidae	White bass, Morone chrysops (F)	<0.1	0	0	<0.1
	Percidae	Bluntnose darter, Etheostoma chlorosomum (F)	<0.1	0	<0.1	0
		Dusky darter, Percina sciera (F)	<0.1	<0.1	<0.1	0
	Sciaenidae	Freshwater drum, Aplodinotus grunniens (F)	<0.1	0	<0.1	0
		Sand weakfish, Cynoscion arenarius (M)	0.1	0	<0.1	0.1
		Spot, Leiostomus xanthurus (M)	0	<0.1	0	<0.1
		Atlantic croaker, Micropogonias undulates (M)	0.6	0.2	0	0.8
Pleuronectiformes	Achiridae	Lined sole, Achirus lineatus (M)	<0.1	<0.1	<0.1	0.1
		Hogchoker, Trinectes maculatus (M)	<0.1	<0.1	<0.1	<0.1
	Paralichthyidae	Bay whiff, Citharichthys spilopterus (M)	0.2	<0.1	0	0.2
Siluriformes	Ictaluridae	Blue catfish, Ictalurus furcatus (F)	<0.1	0	<0.1	0
		Channel catfish, Ictalurus punctatus (F)	0.1	<0.1	<0.1	0.1

Figure 3. Hydrograph showing mean daily discharge in the Neches River during the study period (2012) and mean daily discharge for April–August based on 2002–2015 records. Data from United States Geological Survey gauge #08041780 (Beaumont Saltwater Barrier) are adjusted for tidal influence.

Table 3. Fish species richness and average catch-per-unit effort for gillnet and surveys at two sites located above the saltwater barrier on the Lower Neches River and six sites below the saltwater barrier during months when the barrier was either open or closed (CPUE for gillnet samples is no. of specimens/10 m/h based on a standard experimental gillnet; CPUE for seine samples is no. of specimens/m based on a standard seine).

	Gillnet		Seine
Survey month	Above	Below	Above	Below
Species richness
May (Open)	8	22	32	32
June (Closed)	13	23	19	20
July (Open)	8	17	21	32
August (Closed)	8	18	16	21
CPUE
May (Open)	0.09	0.11	22.9	67.8
June (Closed)	0.26	0.20	8.6	11.4
July (Open)	0.60	0.10	6.4	18.0
August (Closed)	0.21	0.14	8.1	12.6

Table 4. Percent relative abundance of freshwater versus estuarine plus marine fishes from gillnet and seine surveys conducted when the saltwater barrier on the Lower Neches River was open or closed and at sites above or below the barrier.

	Barrier period		Barrier location
	Open	Closed	Above	Below
Gillnet
Freshwater	26.5	23.3	76.1	17.4
Estuarine+marine	73.5	76.7	23.9	82.6
Seine
Freshwater	71.0	69.3	83.2	65.6
Estuarine+marine	29.0	30.7	16.8	34.4

Figure 4. The first two axes from principal components analysis (PCA) of gillnet catch-per-unit effort (CPUE) data in the Neches River. Dots indicate locations of site surveys in ordination space. In the top plot, dot shades indicate whether the saltwater barrier was open or closed when samples were collected and near or distant from the MeadWestvaco paper mill effluent discharge; in the bottom plot, dot shades indicate whether samples were collected above the saltwater barrier, below the barrier and distant from the paper mill effluent discharge, or below the barrier and near the paper mill effluent discharge. Locations of text reveal species (text containing first two letters of the genus name and first two letters of the species name) loadings on each axis and correlations of environmental variable (text at vector tips) with each axis.

Figure 5. The first two axes from PCA of seine CPUE data in the Neches River. Dots indicate locations of site surveys in ordination space. In the top plot, dot shades indicate whether the saltwater barrier was open or closed when samples were collected and near or distant from the MeadWestvaco paper mill effluent discharge; in the bottom plot, dot shades indicate whether samples were collected above the saltwater barrier, below the barrier and distant from the paper mill effluent discharge, or below the barrier and near the paper mill effluent discharge. Locations of text reveal species (text containing first two letters of the genus name and first two letters of the species name) loadings on each axis and correlations of environmental variable (text at vector tips) with each axis.