The first mass-produced anti-lock braking systems (ABS) were introduced in 1985. By 2008, almost every passenger vehicle came standard with ABS. Next, electronic stability control (ESC) became a mandated safety feature for the 2012 model year. Along with all these advancements have come false activation complaints. Solving these has been a diagnostic conundrum through the years. Related Articles- Spotting Brake System Failures- High-End Ride Control Rehab- The Complete Shock And Strut SwapFalse activation incidents involve the ABS modulator taking over braking or intervening to restore vehicle stability. The customer may feel feedback in the brake pedal like a pulsation or sudden drop. Some may also experience a drop in power or the vehicle may suddenly pull in one direction.
The most common complaint on older vehicles is ABS activation at speeds between 3-15 mph. This problem usually starts with the wheel speed sensors. A weak signal from a sensor is interpreted as a locked wheel, which triggers the computer to activate the ABS system and release brake pressure in an attempt to unlock the wheel. The driver might experience a longer than normal stop.
On these older systems with passive sensors, the cure for false activation is to clean the tip of the wheel speed sensor, inspect the tone ring and adjust the air gap. This typically fixes the problem.
The next false-activation scenario involves the ESC system. The source of the problem can be more than one sensor and can even be traced to alignment angles. The customer may not notice an issue until there is a mechanical problem with the brakes. In these cases, you may notice that one wheel is covered in brake dust. Some customers may complain the ESC activates on slower corners or on highway off ramps.
Hot water (not scalding) makes the pain from a stingray go away by breaking down the toxin. This may take more than an hour of soaking, so be patient. Also, remember that a stingray injury causes a laceration so make sure you disinfect it after soaking and keep an eye out for later infection.
The historic depletion of large predators of round stingrays (sharks, giant sea bass, sea lions) has resulted in a population left largely unchecked resulting in population increases over the last 50 years. In addition, the loss of estuarine habitat used by round stingrays has driven populations to seek out suitable habitat along coastal beaches in closer proximity to people.
Because of this input of very warm water to the local environment more stingrays are attracted to the area. Hoisington & Lowe 2005 conducted a study to examine the abundance and distribution of round stingrays (U. halleri) in Seal Beach near this warm water outfall (Fig. 6).
Hoisington & Lowe 2005 found that round stingray abundance is greatest within the first 30m (approx. 100 ft.) from shore where most beachgoers are found. Abundance was also greater in Seal Beach when compared to the nearby control site in Surfside, CA which does not receive an input of warm water.
Round stingray abundance during sampling was negatively correlated with swell height (i.e. as swell height increases abundance decreases). Abundance within the first 30 m from shore is greater when conditions are calm (i.e. low swell, Fig. 14).
During most times of the year male round stingrays are more abundant nearshore, but between the months of June and September-October female stingray abundance increases. This is likely due to mating during the early summer and for a reproductive benefit to females in the fall.
Female round stingray teeth are rounded and diamond shaped. Females do not exhibit differences in tooth shape between juveniles and adult stages, but mature females have significantly larger teeth than juvenile females.
Mature male round stingray teeth are larger than mature female round stingray teeth and become more triangular in shape only during the breeding season, as males use their teeth to hold females for during copulation. After mating season, male round stingray detention returns to flat, plate-like teeth used for crushing clams and crustaceans.
The city of Seal Beach, CA has historically implemented various strategies in order to help reduce the number of stingray related injuries. Many proposed programs did not have a significant impact on reducing the number of stingray related injuries and have been discontinued.
Follow up mark and recapture studies at Seal Beach reported low recapture rates despite a high sampling effort, indicating that the round stingray population in Seal Beach is very mobile with a high turnover rate (Vaudo and Lowe 2006, Lowe et al. 2007).
Given the size of the population and the amount of new stingrays that can be found in the area, particularly during the summer/fall months when stingray abundance is at its peak, a stingray spine clipping program was deemed impractical and unrealistic to implement.
Therefore, the best defense against stingray related injuries is to remember to shuffle your feet and to educate beach visitors about the local wildlife they may come into close contact with during their visit.
Vaudo and Lowe 2006 investigated the fine-scale movement patterns of round stingrays caught in Seal Beach near the mouth of the San Gabriel River and determined whether round stingrays exhibit any site fidelity to Seal Beach.
Round stingrays exhibit the potential to travel longer distances as was the case when one female tagged at Seal Beach was captured and released >30 km (15 mi) south in Upper Newport Bay two months later. The same female was then detected back at Seal Beach one year after initial tagging.
Active tracking showed that round stingrays exhibited short movements interspersed by 2-4 hr. periods of inactivity and that round stingray movement was greatest at night during the ebbing (falling) tide when water temperature can increase as much as 10 degrees (C) in a relatively short period of time. Possible explanations of this increased activity could be to find more desirable conditions, increase foraging success, or find potential mates.
Hale and Lowe 2008 conducted a growth and age structure study of the round stingray (U. halleri) population at Seal Beach, CA. Estimates of age were determined by analysing the vertebral growth rings of round stingrays (U. halleri) collected from Seal Beach. Growth rate coefficient (K) and theoretical maximum disc width (WD) were estimated using the von Bertalanffy growth model.
This information was used in conjunction with size-frequency data from periodic sampling conducted at Seal Beach to determine age structure of the local round stingray population. From this study it was found that the population of round stingrays at Seal Beach is composed mostly of sexually mature adults. Additional findings were that round stingrays are slow growing relative to other species in the family Urolophidae.
Round stingrays have an annual reproductive cycle with peaks in mating occurring from May-July. Round stingrays have a gestation period of 3-4 months and may give birth to litters of 1-6 pups. Birth occurs from August - November (Babel 1967, Mull et al. 2010(a), Lyons and Lowe 2013).
Females sexually segregate to avoid aggressive interactions during non-mating seasons and to seek warmer coastal waters during gestation (Hoisington and Lowe 2005, Mull et al. 2010, Jirik and Lowe 2012). Males are not found in warmer coastal waters as much as females possibly due to a sex-specific energetic cost from residing in areas of increased temperatures for extended periods (Jirik and Lowe 2012).
Lyons and Lowe 2013 used round stingrays as a model species to determine pathways of contaminant transfer, the quantity of contaminants offloaded by females, and the relative proportion of organic contaminant groups (PCBs, DDTs, and chlordanes) transferred from mother to embryo.
Female round stingrays appear to offload less contaminants to their offspring via this mode of reproduction compared to other elasmobranch species. Further research should continue to examine maternal offloading in other elasmobranch reproductive modes and the physiological effects of contaminant exposure in developing embryos and neonates.
Mull et al. 2010(b) characterized the reproductive cycle of male round stingrays from Seal Beach, CA by examining changes in testes morphology, spermatogenesis, and steroid hormone concentrations throughout their reproductive cycle.
The reproductive cycle of male round stingrays is annual and many aspects of reproduction are highly regulated. Males experience increases in Gonadosomatic Index (GSI) from July-October with peak GSI in October. Testosterone (T) production remains low from April-June then increases until peak production in March. 11-Ketotestosterone (11-KT) concentrations followed a similar pattern but peak production occurred in February. Sperm production peaks in December and is stored long term until favorable mating conditions are present.
Microsatellite analysis of round stingrays collected from sites in Southern California, Gulf of California, and Santa Catalina Island to determine level connectivity and structure was conducted by Plank et al. 2010.
Graduate student Lorena Silva Garay is investigating the effects of size and temperature on the metabolic rate of round stingrays across its entire size range. The goals of her project are to estimate the Standard Metabolic Rate (SMR) and metabolic Q10 of round stingrays across a range of temperatures and predict the species-specific scaling exponent of metabolic rate for round stingrays. This is one of the first studies to estimate these parameters across the entire size range of an elasmobranch species.
While Q10 did not significantly vary between sexes, juvenile and adult round stingrays exhibited significant differences in thermal sensitivity; juveniles displayed a higher Q10 than was estimated for adults when accounting for the interacting effects of temperature and body mass.
The overall thermal sensitivity of round stingrays is relatively higher than previously reported values for other elasmobranchs. In adult round stingrays, the combined results of a plateauing SMR with increased temperature and relatively lower Q10 is likely indicative of a broader range of thermal optima for larger individuals. The broader thermal optima in adult round stingrays is consistent with the seasonal changes in water temperature experienced in their environment. 2b1af7f3a8