1. A comparison of environmental variation in estuaries inhabited by the endangered tidewater goby (Eucyclogobius newberryi) with that in estuaries occupied by the non-endangered sister species, arrow goby (Clevelandia ios)
Brenton T. Spies and Mark A. Steele
California State University Northridge
Conclusions
Abstract
Our results show significant latitudinal variation in estuaries inhabited by the tidewater goby and those frequently inhabited by its closest relative, the arrow goby.
We found that:
Estuaries inhabited by the tidewater goby experience higher
fluctuations in temperature and salinity
This is most likely caused by seasonal closures and smaller size
The tidewater goby generally inhabits estuaries that contain somewhat persistent low-salinity areas
The arrow goby generally prefers cooler, and higher salinity habitats
There was no difference in pH or dissolved oxygen between the two types of estuaries, but this result may not reflect longer-term patterns .
Estuaries in California are highly variable transitional zones of the coastal marine environment. Factors such has temperature, annual precipitation, and freshwater input vary among estuaries and can affect the dynamics of each estuary and the species that inhabit it. The first step in understanding the effects of such environmental variation is documenting the patterns of environmental variation.
Zack Larson
Tidewater Goby (Eucyclogbius newberryi)
Arrow Goby (Clevelandia ios)
Introduction
Results
Mark Steele
Species such as the endangered tidewater goby (Eucyclogobius newberryi) may be predisposed to local extirpation due to their preference for highly seasonally variable estuaries. The tidewater goby generally inhabits estuaries that contain somewhat persistent low-salinity areas. This preference differs from that of its closest relative, the arrow goby (Clevelandia ios), which inhabits cooler, higher salinity estuaries.
Objective
Evaluate the variation in habitat characteristics of known tidewater goby sites relative to that of non-tidewater goby habitats where the arrow goby was abundant.
Arrow Goby
Tidewater Goby
Temperature (°C)
Methods
Date/Time (hours)
Temperature Data
Temperature was recorded hourly from July – October 2011
Ibutton thermocron data loggers
20 estuaries spanning the coast of California were sampled
11 known tidewater goby sites (seasonally closed estuaries)
9 known arrow goby sites (fully tidal year round)
Figure 5: Las Flores lagoon, San Diego CA. This is a seasonally closed estuary inhabited by the Endangered tidewater goby in high abundance.
Future Research
This project is a preliminary study for a larger project looking at the effects of latitudinal variation on early life history characteristics of study species, the arrow goby and tidewater goby.
Objectives:
Determine if pelagic larval duration, size at settlement, and post-settlement growth rate vary latitudinally in both species using otolith analysis.
If differences in early life history traits are seen among latitudes, how do these correlate with temperature differences?
Date/Time (hours)
Figure 2: Hourly temperature recordings from July 10 - August (Top) San Lorenzo River, a fully tidal estuarine habitat inhabited by the arrow goby, Clevelandia ios. (Bottom) Santa Clara River, a seasonally closed habitat inhabited by the tidewater goby, Eucyclogobbius newberryi. Dotted line represents seasonal closure.
Tidewater Goby sites had more variable average temperatures than arrow goby sites
The arrow goby is generally found in much cooler, fully tidal habitats.
Salinity was lower in tidewater goby sites than arrow goby sites (t=4.434, df=18, p<0.0001)
pH (t=-0.303, df=18, p=0.766) and DO (t=0.134, df=18, p=0.895) did not differ between sites inhabited by the two species
Figure 1: ibutton thermocron temperature logger with water proof PVC housing
Water Quality Data
Salinity, pH, and dissolved oxygen (DO) measured a single
time at each site
YSI 556 used for all parameters
A total of 5 measurements were taken at each site at least
50-meters apart
Tidewater Goby Sites (North to South)
Big Lagoon, Tenmile River, Pudding Creek, Rodeo Lagoon, San
Gregorio Creek, Moore Creek, San Luis Obispo Creek, Santa
Ynez River, Arroyo Burro, Santa Clara River, Las Flores Lagoon
Arrow Goby Sites (North to South)
Arcata Bay, Bodega Bay, Tomales Bay, San Lorenzo River,
Elkhorn Slough, Morro Bay, Carpinteria Salt Marsh, Alamitos
Bay, Los Peñasquitos
Acknowledgements
Special thanks to David Jacobs, Camm Swift, Kevin Lafferty, Mike Rouse, Darren Fong, and Rikke Kvist Preisler for their help in the field and detailed knowledge. I would also like to thank Larry Allen and Steve Dudgeon for their continued support and advisement. This research was supported by the Nearshore Marine Fish Research Program, IWFA Scholarship, CSUN Thesis Support Program, and the Norris Travel Grant. Additional data provided by Elkhorn Slough National Estuarine Research Reserve, SLOSEA, and USFWS.
Water Quality
Figure 3: Latitudinal temperature variations of seasonally closed (n=11) and fully tidal (n=9) estuaries
Figure 4: Water quality parameters taken as single time measurements. Salinity,pH, and DO were compared among tidewater goby sites (n=11) and arrow goby sites (n=9)