You may use the information and images contained in this document for non-commercial, personal, or educational purposes only, provided that you (1)

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1 You may use the information and images contained in this document for non-commercial, personal, or educational purposes only, provided that you (1) do not modify such information and (2) include proper citation. If material is used for other purposes, you must obtain written permission from the author(s) to use the copyrighted material prior to its use.

2 Alex Miller and George Guillen University of Houston- Clear Lake

3 Importance of Gulf Coast Estuaries Commercial harvesting supports economy (Zimmerman et al. 22) Fish assemblages are indicators of water quality (Araujo et al. 2)

4 Riverine Deltaic Estuary Brazos estuary is unique Highly dynamic system Complex, fluctuating species assemblages

5 Study Objectives Relationship of freshwater inflow on: o Salinity o Water quality o Available habitat o Nekton community Needed for adaptive management

6 Data Collections Methods Review of Past Studies on lower Brazos River o Biological: bottom trawl collections o Hydrological: mean daily and monthly flow o Water quality: temperature, salinity, dissolved oxygen New Data collection on lower Brazos River

7 Nekton Studies Brazos River Johnson (1977) TPWD o Inventory lower Brazos nekton monthly; Emmitte (1983)- Dow Chemical o Inventory lower Brazos nekton; 1982

8 Sampling Approach New Data Sampled 4 of Johnson s sites each month for 1 year Water Quality: o o YSI multiprobe data logger: Temp, DO, Sp. Cond., Salinity, ph and depth Turbidimeter: water clarity (NTU) Hydrology o USGS gage at Rosharon Fish Collection: Otter trawls, supplemented with other methods

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10 Data Analysis Graphical comparisons of hydrology, species numbers and abundance Used IHA (Index of Hydrological Alteration = IHA) to evaluate long term trends in hydrology Multivariate Cluster Analysis: relation to species similarity with sites and times

11 Current Study Results

12 Salinity (psu) Salinity by River Km River km 3 4

13 PCO2 (21% of total variation) 2 ter Temp ( C) 11.7 Normalise Resemblance: D1 Euclidean distance Site Salinity (psu) 21.5 D.O.(mg/L) Depth (m) PCO1 (69.4% of total variation)

14 Physiochemical Sample Similarity Mar-21.5 Mar-42.4 Aug-42.4 Sep-42.4 Jun-21.5 Aug-21.5 Jul-21.5 Sep-21.5 May-21.5 Jun-42.4 Jul-42.4 May-42.4 Oct-21.5 Oct-42.4 Nov-42.4 Dec-42.4 Jan-21.5 Nov-21.5 Dec-21.5 Dec-11.7 Jan-11.7 Dec-.6 Jan-.6 Nov-.6 May-11.7 May-.6 Jun-.6 Sep-.6 Jul-.6 Nov-11.7 Jun-11.7 Aug-11.7 Oct-.6 Oct-11.7 Jul-11.7 Aug-.6 Sep-11.7 Apr-21.5 Apr-42.4 Jan-42.4 Feb-21.5 Feb-42.4 Feb-.6 Feb-11.7 Mar-11.7 Mar-.6 Apr-.6 Apr-11.7 Samples Distance Normalise Resemblance: D1 Euclidean distance RKM

15 Distance 4 3 Physiochemical Site Similarity Normalise Resemblance: D1 Euclidean distance Site Site

16 RKM Julian Day Secchi (m) D.O.(mg/L) Salinity (psu) Water Temp ( C) Salinity (psu) D.O.(mg/L) Secchi (m) sfdgfghgfhd ghgdhdhdf ghgfhddhd dfhhgfhlklk -1 1 lklkl Julian Day

17 Dominant Nekton Category bay anchovy Atlantic croaker brown shrimp white shrimp sand seatrout gulf menhaden striped anchovy blue catfish silver perch spot

18 Abundant Taxa MDS Transform: Log(X+1) Resemblance: S17 Bray Curtis similarity 2D Stress: Site la chrysoura us aztecus s undulatus Brevoortia Patronus Ictaluris furcatus 21.5 Cynoscion arenarius 11.7 Anchoa mitchilli Litopenaeus setiferus Anchoa hepsetus Leiostomus xanthurus

19 Transform: Log(X+1) Resemblance: S17 Bray Curtis similarity 2D Stress:.13 Oct Jan Anchoa hepsetus Litopenaeus setiferus Aug Dec Feb Anchoa mitchilli Sep Bairdiella chrysoura Nov Cynoscion Leiostomus arenarius xanthurus Micropogonis undulatus Jul Brevoortia Patronus Ictaluris furcatus Mar Farfantepenaeus aztecus May Jun Apr

20 No. Taxa Cumulative No. Nekton Taxa 12 month Period Site KM

21 Total Number of Nekton Taxa by Month and Site 25 2 Site KM Month

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23 Aug-42.4 Mar-42.4 Jul-21.5 Sep-42.4 Jul-42.4 Jun-42.4 Jun-21.5 Mar-21.5 Feb-42.4 Feb-21.5 Apr-42.4 Apr-21.5 Jan-21.5 Jan-42.4 Aug-21.5 Sep-.6 Jul-.6 Jul-11.7 Oct-.6 Nov-.6 Apr-.6 Dec-.6 Dec-21.5 Oct-11.7 Oct-21.5 Oct-42.4 Sep-21.5 Nov-21.5 May-11.7 Nov-42.4 May-.6 Dec-42.4 May-21.5 Aug-.6 Jun-.6 Jan-11.7 Jun-11.7 Nov-11.7 Dec-11.7 Aug-11.7 Sep-11.7 Jan-.6 Mar-.6 Mar-11.7 Apr-11.7 May-42.4 Feb-11.7 Feb-.6 Similarity 2 Nekton Presence Assemblage Similarity Transform: Presence/absence Resemblance: S17 Bray Curtis similarity RKM Samples

24 Aug-42.4 Mar-42.4 Jul-21.5 Sep-42.4 Jul-42.4 Aug-21.5 Jan-21.5 May-42.4 Mar-21.5 Feb-21.5 Apr-21.5 Feb-42.4 Apr-42.4 Jun-42.4 Jun-21.5 Apr-11.7 Sep-.6 Oct-.6 Feb-11.7 Dec-.6 Jan-42.4 Oct-21.5 Jan-11.7 Nov-.6 Jan-.6 Feb-.6 Mar-.6 Mar-11.7 Sep-21.5 Oct-11.7 Apr-.6 Jun-.6 May-.6 Aug-.6 Jul-.6 Jul-11.7 Oct-42.4 Nov-42.4 Dec-11.7 Dec-21.5 May-21.5 Jun-11.7 Nov-11.7 Aug-11.7 Sep-11.7 May-11.7 Nov-21.5 Dec-42.4 Similarity 2 Nekton Community Similarity Transform: Log(X+1) Resemblance: S17 Bray Curtis similarity RKM Samples

25 Comparison with Past Studies Hydrologically different Effort and duration varied Current study: 4 sites, RKM, 3 replicates ; 12 months; 144 total tows Johnson : 5 sites, RKM, 2 replicates; 24 months; 24 tows Emmitte 1982: 4 sites, RM, 16 tows; 12 months (quarterly), no replicates

26 Index of Hydrological Alteration Johnson Emmitte 1983 Current Study

27 Dai l y Aver age Fl ow ( c fs) Daily Average Flow by Year (75th) 6844 (med) (25th) Year

28 Dai l y Avg. Fl ow ( c fs) Daily Avg. Flow by Month Median Q1 Q Month

29 No. Taxa Average No. Taxa by Study Study Emitte 1983 Johnson 1977 Present KM

30 Species Johnson 4.5 Johnson 8.9 Johnson 15 Johnson 22 Johnson 3 Emmitte 3 Emitte 6 Emmitte 8 Emmitte 9.5 Current 4.5 Current 8.1 Current 13.6 Current 26.6 Actractosteus spatula 1 Elops saurus 1 1 Brevoortia patronus Dorosoma cepedianum Dorosoma petenense Harengula pensacolae Opisthonema oglinum 1 Clupeid spp. 1 Anchoa mitchilli Hyobopis aestivalis Ictalurus fucatus Ictalurus punctatus Arisu felis Bagre marinus Porichthys plectrodon Histrio histrio 1 Mugil cephalus Mugil curema 1 Menidia sp. 1 Sygnathus pelagicus 1 Centropomus undecimalis Caranx hippos Chloroscombrus chrysurus Selene vomer 1 1 Selene setapinnis 1 1 Trachinotus carolinus 1 Lutjanus griseus Eucinostomus argenteus 1 Eucinostomus melanopterus 1 Orthopristis chrysoptera 1 1 Archosargus probatocephalus Lagodon rhomboides Polydactylus octonemus Aplodinotus grunniens 1 1 Bairdiella chrysura Cynoscion arenarius Cynoscion nebulosus 1 Larimus faciatus Leiostomus xanthurus Menticirrhus americanus Micropogonias undulatus Pogonias cromis 1 1 Sciaenops ocellata Stellifer lanceolatus Sciaenidae sp. 1 1 Chaetodipterus faber 1 1 Scomberomorus macuatus 1 1 Astroscopus y-graecum 1 Ctenogobius boleosoma Gobionellus hastatus 1 Ctenogobius shufeldti 1 Gabionellus oceanicus 1 Gobiiedae spp. 1 1 Trichiurus lepturus 1 1 Peprilus alepidotus 1 Peprilus triacanthus 1 1 Prionotus tribulus 1 Symphurus piger 1 Citharichthys spilopterus Paralichthys lethostigma

31 Discussion Decreased peak Brazos River freshwater inflows Flow regime impacts lower river nekton communities more so than upper reaches Greatest diversity at the mouth of river

32 Literature Cited Araujo, F. G., and W. P. Williams. 2. Fish assemblages as indicators of water quality in the Middle Thames Estuary, England ( ). Estuaries 23: Emmitte, J A comparative study of two river estuaries. Dow Chemical Independent Report. Johnson, R. B Fishery survey of Cedar Lakes and the Brazos and San Bernard River Estuaries. Texas Parks and Wildlife Technical Series (23):1-6. Phillips, J. D. 26. Geomorphic context, constraints, and changes in the lower Brazos and Navasota Rivers, Texas. Texas Water Development Board. Sklar, F. H., and J. A. Browder Coastal environmental impacts brought about by alterations to freshwater flow in the Gulf of Mexico. Environmental Management 22(4): Tsou, T.-S., and J. Richard E. Matheson. 22. Seasonal changes in the nekton community of the suwannee river estuary and the potential impacts of freshwater withdrawal. Estuaries 25(6B): Zimmerman, R. J., T. J. Minello, and L. P. Rozas. 22. Salt marsh linkages to productivity of penaeid shrimp and blue crabs in the northern Gulf of Mexico. Concepts and Controversies in Tidal March Ecology:

33 Thanks to all who helped!

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