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IDENTIFYING THE EFFECTS OF ALGAL TURBIDITY ON THE REPRODUCTIVE SUCCESS AND MATING BEHAVIORS OF DWARF SEAHORSES (HIPPOCAMPUS ZOSTERAE)**

Abstract

Coastal marine communities are particularly vulnerable to nutrients that can cause human-induced eutrophication that has been shown to alter various aspects of aquatic life. This experiment investigated the effects of algal turbidity on mating and reproductive success of the genetically monogamous dwarf seahorse (Hippocampus zosterae). To determine the effect of algal turbidity on seahorses in varied sex-ratios, each replicate consisted of six tanks, including an equal 1:1 sex ratio and two sex-biased treatments (2 females:1 male and 2 males:1 female) set up in clear and turbid water (n=3, 48 seahorses with each fish used only once). Ongoing analyses of mating behaviors using the BORIS program indicate that majority of courting occurred during the early morning hours on the second and third morning after introduction. Mate preference in the male-biased treatments was determined to be influenced by the male activity levels rather than their body size. Latency in mating had an inverse relation with the number of offspring. The latency to mate for seahorses in clear water treatments was 3.67 ± 1.36 days compared with 2.78 ± 0.64 days for the turbid water treatments. Competition in male-biased treatments led to longer latency to mating, lower reproductive success for females, and unsuccessful egg transfers. The gestation period for males did not differ across treatments and averaged around about 12 days. However, males in turbid treatments had an average of 20.4 ± 5.8 offspring compared to an average of 10.1 ± 6.9 offspring in clear water treatments. The greater reproductive success in turbid treatments may be due to adaptations in seahorses collected from Tampa Bay where animals are exposed to a wide range of turbidities throughout different seasons. Additional replicates will be conducted next summer to create a robust data set for statistical analysis to determine the effects of algae on seahorse reproduction.

Acknowledgements

BSRI Summer 2021, VSU Department of Biology

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