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Environmental influences on the spatial ecology of juvenile smalltooth sawfish (Pristis pectinata): results from acoustic monitoring.

Simpfendorfer CA, Yeiser BG, Wiley TR, Poulakis GR, Stevens PW, Heupel MR - PLoS ONE (2011)

Bottom Line: The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales.Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range.Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery.

View Article: PubMed Central - PubMed

Affiliation: Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America. colin.simpfendorfer@jcu.edu.au

ABSTRACT
To aid recovery efforts of smalltooth sawfish (Pristis pectinata) populations in U.S. waters a research project was developed to assess how changes in environmental conditions within estuarine areas affected the presence, movements, and activity space of this endangered species. Forty juvenile P. pectinata were fitted with acoustic tags and monitored within the lower 27 km of the Caloosahatchee River estuary, Florida, between 2005 and 2007. Sawfish were monitored within the study site from 1 to 473 days, and the number of consecutive days present ranged from 1 to 125. Residency index values for individuals varied considerably, with annual means highest in 2005 (0.95) and lowest in 2007 (0.73) when several P. pectinata moved upriver beyond detection range during drier conditions. Mean daily activity space was 1.42 km of river distance. The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range. Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery.

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Related in: MedlinePlus

Salinity electivity of Pristis pectinata in the Caloosahatchee River estuary revealing a preference for salinities from 18 to at least 24 psu.Sample sizes above 24 psu were small, limiting the ability to make conclusions.
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pone-0016918-g007: Salinity electivity of Pristis pectinata in the Caloosahatchee River estuary revealing a preference for salinities from 18 to at least 24 psu.Sample sizes above 24 psu were small, limiting the ability to make conclusions.

Mentions: During the study, water temperature ranged from 14.6 to 32.6 C, salinity ranged from 0.1 to 33.6 psu and freshwater inflow ranged from 0.0 to 627.4 m3s−1. Pristis pectinata were present throughout the entire range of these environmental conditions. Salinity was negatively correlated with flow (r2 = 0.646, p<0.001). There were positive correlations between P. pectinata log-transformed mean daily river location and salinity (Figure 5a; r2 = 0.126, p<0.001) and log-transformed mean daily river location and temperature (Figure 5c; r2 = 0.016, p<0.05). There was a negative relationship between log-transformed mean river location and flow (Figure 5b; r2 = 0.116, p<0.001). Distribution of P. pectinata within the river (Figure 6) indicated a significantly different proportion of detections by river location between years (χ2 = 28766, df = 48, p<0.001). Differences between years were likely driven in part by differences in flow regime. During 2005, when flows were high, individuals were in the lower reaches of the river, while periods of little or no flow in 2007 corresponded to periods when individuals were far upriver. This suggests flow, in conjunction with physical factors such as depth, plays some role in individual location within the river, possibly through their influence on salinity. Electivity analysis demonstrated that P. pectinata had an affinity for salinity values between 18 and at least 24 psu (Figure 7). At salinities above 24 psu sample sizes were small and conclusions limited.


Environmental influences on the spatial ecology of juvenile smalltooth sawfish (Pristis pectinata): results from acoustic monitoring.

Simpfendorfer CA, Yeiser BG, Wiley TR, Poulakis GR, Stevens PW, Heupel MR - PLoS ONE (2011)

Salinity electivity of Pristis pectinata in the Caloosahatchee River estuary revealing a preference for salinities from 18 to at least 24 psu.Sample sizes above 24 psu were small, limiting the ability to make conclusions.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037940&req=5

pone-0016918-g007: Salinity electivity of Pristis pectinata in the Caloosahatchee River estuary revealing a preference for salinities from 18 to at least 24 psu.Sample sizes above 24 psu were small, limiting the ability to make conclusions.
Mentions: During the study, water temperature ranged from 14.6 to 32.6 C, salinity ranged from 0.1 to 33.6 psu and freshwater inflow ranged from 0.0 to 627.4 m3s−1. Pristis pectinata were present throughout the entire range of these environmental conditions. Salinity was negatively correlated with flow (r2 = 0.646, p<0.001). There were positive correlations between P. pectinata log-transformed mean daily river location and salinity (Figure 5a; r2 = 0.126, p<0.001) and log-transformed mean daily river location and temperature (Figure 5c; r2 = 0.016, p<0.05). There was a negative relationship between log-transformed mean river location and flow (Figure 5b; r2 = 0.116, p<0.001). Distribution of P. pectinata within the river (Figure 6) indicated a significantly different proportion of detections by river location between years (χ2 = 28766, df = 48, p<0.001). Differences between years were likely driven in part by differences in flow regime. During 2005, when flows were high, individuals were in the lower reaches of the river, while periods of little or no flow in 2007 corresponded to periods when individuals were far upriver. This suggests flow, in conjunction with physical factors such as depth, plays some role in individual location within the river, possibly through their influence on salinity. Electivity analysis demonstrated that P. pectinata had an affinity for salinity values between 18 and at least 24 psu (Figure 7). At salinities above 24 psu sample sizes were small and conclusions limited.

Bottom Line: The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales.Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range.Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery.

View Article: PubMed Central - PubMed

Affiliation: Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America. colin.simpfendorfer@jcu.edu.au

ABSTRACT
To aid recovery efforts of smalltooth sawfish (Pristis pectinata) populations in U.S. waters a research project was developed to assess how changes in environmental conditions within estuarine areas affected the presence, movements, and activity space of this endangered species. Forty juvenile P. pectinata were fitted with acoustic tags and monitored within the lower 27 km of the Caloosahatchee River estuary, Florida, between 2005 and 2007. Sawfish were monitored within the study site from 1 to 473 days, and the number of consecutive days present ranged from 1 to 125. Residency index values for individuals varied considerably, with annual means highest in 2005 (0.95) and lowest in 2007 (0.73) when several P. pectinata moved upriver beyond detection range during drier conditions. Mean daily activity space was 1.42 km of river distance. The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range. Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery.

Show MeSH
Related in: MedlinePlus