Tidal Currents Effect on Epibenthic Growth in Marine Ecosystems

TIDAL CURRENTS EFFECT ON EPIBENTHIC GROWTH IN MARINE ECOSYSTEMS A PAPER SUBMITTED FOR COMPLETION OF SENIOR RESEARCH FOR THE COLLEGE OF ARTS AND SCIENCES STETSON UNIVERSITY BY JESSICA L. STEIN IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE(S) OF BACHELOR OF SCIENCE ENVIRONMENTAL SCIENCE ADVISOR Dr. Jason M. Evans, Ph.D. MAY 2017 ii Table of Contents Introduction 1 Literature Review 2 Methods and Study Area 6 Results 9 Discussion and Observations 10 Conclusion 12 Works Cited 14 List of Illustration Figure 1. Floating dock at Inlet Harbor in Ponce Inlet, Fl. 6 Figure 2. Study Area, Map of Ponce Inlet, Fl. 7 Figure 3. Samples showing an increase in settlement in areas 10 of higher water velocity. List of Tables Table 1. Example of BEAMR Datasheet. 9 Acknowledgements I would like to thank Dr. Jason Evans, Dr. Wendy Anderson, Dr. Terence Farrell, and Chad Macfie (Marine Science Center) for mentoring me during this research. This study was funded by Stetson’s Institute of Water and Environmental Resilience and Dean’s Funding. Abstract Artificial reefs give us the opportunity to study marine ecology, how organisms have adapted to certain resources and how they arrived (Speight and Henderson 2010). Artificial reefs such as floating docks create a diverse surface area for epibenthic encrusting organisms to attach as the water currents disperse larvae (Dunstan 1984). The purpose of this study is to determine the effects of currents on the epibenthic colonization of a floating dock habitat at the Inlet Harbor Floating Docks in Ponce Inlet, Florida. If areas of increased water currents show higher probability of epibenthic growth, then the expectation is to see an increase in colonization and diversity in areas of higher current flow. Once we know how these organism’s larvae are recruited we will better understand how these animals develop at these sites and how they got to those individual sites and settlement based on each species.1 Introduction Artificial reefs give us the opportunity to study marine ecology, how organisms have adapted to certain resources and how they arrived (Speight and Henderson 2010). Artificial reefs such as floating docks create a diverse surface area for epibenthic encrusting organisms to attach as the water currents disperse larvae (Dunstan 1984). I studied the effects of currents on the epibenthic colonization of a floating dock habitat at the Inlet Harbor Floating Docks in Ponce Inlet, Florida. If areas of increased water currents show higher probability of epibenthic growth, then the expectation is to see an increase in colonization and diversity in areas of higher current flow. These floating docks provide an ideal location to test my hypothesis because the docks are arranged in an area that encompasses varying tidal currents. Before starting this study, areas of the dock were scraped clean of epibenthic growth beneath the water line to ensure the seeding of a new generation of epibenthic growth and not a previous succession. I then inserted a clean textured panel in front of the cleared areas of the dock to start without any debris covering the surface. I measured epibenthic growth by counting the amount of species found according to each panel location. Here I determined species of fouling organisms using Young’s chart from his report as a guide to sessile epibenthic organisms found in Ponce Inlet, Fl. (Young 1943). Water velocity was determined by the use of a water current measuring device and was measured in the same timeframe as the growth was accounted for. Studying artificial reefs has the potential to assist in building additional sites to study succession and aquatic ecology as well as creating more surface area for epibenthic growth. Once we know how these organism’s larvae are recruited we will better understand how these animals develop at these sites, how they got to those individual sites and settlement based on 2 each species. Collecting data of succession and recruitment on textured materials will provide us with the information of what materials to use when creating new artificial reefs and what organisms are more likely to attach to those surfaces. Literature Review Carter and Prekel’s (2008) previous study discusses the concept of benthic colonization as well as ecological successional patterns. With marginal reefs impacted by beach restoration, artificial reef projects are increasing. To determine long-term success of artificial reef colonization to replace near shore habitat, ecological processes and succession rates are evaluated. This particular report is a research site in Broward County, Florida based on the development, recruitment, and ecological succession rates in these benthic communities. My research is in relation to this report since I studied colonization rates in shallow marine environments. I referenced this information to identify what epibenthic organisms are growing in Ponce Inlet, Florida. Fouling organisms are known to elevate the habitat complexity of these newly constructed artificial reefs. This makes the artificial reefs suitable for housing a variety of organisms such as corals. The results of this study do not indicate a classic directional succession pattern but do indicate a shift in community composition (Carter and Prekel 2008). Although this study does not include any successional pattern as I expected with my research it is relatable because it addresses the concept of benthic colonization and assemblages that were included in my study. I included some aspects of this study as well as methods to determine recruitment and settlement of benthic communities. I particularly chose this report to compare to my senior research in hopes that my study would contribute to the research of artificial reef colonization that are monitored closely as well as how these animals are able to 3 adapt here and attach to textured surfaces. Another conceptual framework is the settlement of benthic marine invertebrates. Rodriguez’ (1993) study of marine organisms’ complex settlement and recruitment is based on the abiotic and biotic factors around them. Rodriguez (1993) explains the importance of recognizing the difference between settlement, the passage from a pelagic to a benthic way of life, and recruitment, referring to the newly settled individuals that have survived to a specific size after settlement. His study defines these processes individually and the factors that affect each process. The objective present in this study is to analyze the settlement process as a whole. This means considering not only ecological aspects but physiological, the study of living organisms’ normal functions, and biotechnical factors, the use of living organisms for development (Rodriguez 1993). Although I did not use all of these processes in my research, I have a better understanding of how these processes work in order to disperse larvae to various artificial reef sites. Also with lack of growth in the first week I was also able to look at the abiotic factors (non-living, such as sunlight, velocity or boats blocking water currents) and biotic factors (living-other organisms effect on growth) while conducting this project. Rodriguez (1993) mentions natural inducers such as settlement-inducing chemical cues that include prey species and microbial films. My research is based on settlement and recruitment of species naturally occurring in the Atlantic Ocean and attaching to artificial reefs such as boating docks. If we are able to fully understand how these organism’s larvae are brought in through the currents and their settlement techniques, we will better understand the materials needed to build artificial reef sites in the future to increase population of species that have a declination of population from various ecosystem changes. 4 The Twelve Months’ Fouling Record was a study on marine exposure and fouling in Ponce Inlet, Florida in 1942-1943 (Young 1943). This experiment included the usage of thirteen untreated blocks submerged in saltwater on piers to measure fouling. These scientists conducted their experiment on the reservation of the lighthouse not far from the floating docks I studied in Ponce Inlet. This information is useful in my research as I too studied fouling organisms on sites in the Ponce Inlet area about a mile from the lighthouse. This report contains a chart with a variety of organisms found in this area as well as a description of each individual organism. A completed research journal is presented in this article containing dates of when each block was surveyed as well as the control which assisted me when I organized my data. Since this experiment happened to be within a mile from my research, I observed similar organisms brought in from the Atlantic Ocean. I used similar methods although the floating docks will provide a much more stable environment because I was able to hang my panels right on the sides since there is not exposure during low tide as they are floating and move with ease with the currents. The Docking Report Manual contains a guide to fouling organisms. This guide includes how ships become fouled and the process of fouling which I compared throughout my study. This report explains three phases that fouling is divided into including a step-by-step process of each phase. I was hoping to visually see each phase period while collecting data in the field, however due to time constraints I was unable to see phases. After researching this study it was easier to keep a complete list of common, visible fouling organisms that belong to at least five main groups, each sorted in two categories: organisms with hard, slimy shells and organisms without shells. This is similar to the layout the docking manual used to organize my data. There 5 are many factors that influence the amount of fouling that occurs on ships and that helped me understand the concepts of ecology and ecosystems. McKinney (2007) explains the long-term changes in shallow marine life similar to the environment my study will take place. He also discusses early diversification of marine animals. In my research, I studied growth and how water currents bring in larvae and their diversification. McKinney (2007) includes examples and concepts of faunal as well as ecosystem succession which is also in conjunction with my research topic. He also addresses which types of individual organisms are detritus feeders, suspension-feeders, deposit-feeders, and/or carnivores which are important in terms of diversification (McKinney 2007). I combined methods from each previous study I have researched as well as developing my own. I used methods such as taking velocity to compare success rates in different areas to answer my hypothesis as to whether velocity does affect recruitment of sessile and epibenthic, near surface encrusting organisms. Taking the abiotic (non-living-such as sunlight, water temperature, water flow) and biotic (living-other sessile organisms) factors into account from previous studies I also used methods of measuring such as photographing each panel as growth develops to compare the abundance of similar organisms in each area. This will tell me whether these organism’s attachment and settlement are affected by abiotic or biotic factors such as their population’s ability to adapt to high or low current flow or even predators. The settlement and competition to of epifauna will be key to the results of this project (Keough 1984). Once I became familiar with the settlement of different organisms I was able to determine the advantages and disadvantages of larval dispersal and how this has an effect on my research (Pechenik 1999). 6 My study investigated the distributional processes of a marine epifaunal community while using a series of manipulated plates (Osman 1977). While this unique method is not used in much of the previous literature I have found, it is more accurate when studying succession rather than fouling on boats because this is more of a natural setting that these organisms will settle on. Textured plates allow for sessile organisms to tighten their grip by taking hold in the small indents of the panels just like they would on rocks in natural reef habitats. With these methods I hope to provide information on local marine systems, their biodiversity, colonization, succession as well as what texture materials they will settle on. This study may also be helpful to show faunal complexity in artificial habitats and the increased potential to augment an abundance of diversity (Hunter 2009). Methods and Study Area Figure 1. Floating dock at Inlet Harbor in Ponce Inlet, Fl. Figure 1, shows the exact floating docks I used for this research. This dock is located at Inlet Harbor Restaurant in Ponce Inlet, Florida. This floating dock acts as an artificial reef containing many sessile organisms such as anemones, tunicates, barnacles, bryozoans, mussels, and a variety of algae. This site encompasses a varying tidal currents and exhibits velocity ranging from high to low. Inlet Harbor’s dock is made from plastic and concrete, an ideal rough 7 substrate for sessile organisms to attach long term. The Figure below shows the location of Ponce Inlet on a map as well as the star indicating close proximity to where my site is located. Figure 2. Map of Ponce Inlet, Florida The first week of this study I obtained all the supplies needed to conduct my research including natural stone tiles (purchased at Lowes Home Improvement), supplies to hang the tiles underwater such as nylon rope (purchased from Lowes Home Improvement), identification books about marine invertebrates, and a flow rate sensor that connects to the Lab Quest 2 data device (both purchased from www.vernier.com). I treated the docks before conducting this study by scraping the data collection sites of any epibenthic growth and debris to ensure a new generation of organisms. Then a hole was drilled at the center of each tile large enough to fit the nylon rope through the tiles. The nylon rope was used to tie off the tiles to the boat cleats on the sides of the 8 docks. Boat cleats are what boaters use to tie their ropes to the dock so their boats don’t drift away. After preparation, I hung the sample tiles accordingly. Each side of the dock, experiencing a different flow rate (low, medium or high) contained four. Velocity was measured in all three areas once a week for three weeks at the highest peak of velocity during the day. The highest peak of velocity is at different times each day depending on when high and low tides come in. Velocity was measured in meters per second (m/s). The same time of day I measured the growth on each tile by counting the amount of species and classifying each species to its family name while taking photographs to document levels of settlement. I did this by taking photographs of the tiles on the sides of the docks as well as removing the samples and placing them in a shallow container of water to further inspect my samples. Growth was measured once a week for three consecutive weeks as well. It is crucial to capture each species during this field study to collect accurate data of the types of organisms that live in this area. To make sure I was organized with my data I created a chart per day that lists the sample tile number, species found, and percent cover. Below is an example of a BEAMR chart is used. 9 Table 1: Example of a BEAMR datasheet. I studied inventory of all collected data at the end of my data collection coming to the conclusion as to whether my hypothesis was supported. Diversity indices were analyzed to distinguish species recruited as well as settlement in this area to create a regression in excel. This regression shows the relationship between current flow rate and number of species found at each tile site. Results The following graph displays a significant result to the 90th percentile leaving room for error due to small sample size. Samples show an increase in settlement in areas of higher water velocity, thus supporting my hypothesis. 10 Figure 3. Samples show an increase in settlement in areas of higher water velocity At the low velocity site where the channels are more stagnant, only one out of the four tiles showed growth. That one tile contained an anemone at log of velocity -2.04 m/s. Medium velocity samples contained algae growth (an organism not counted in this study) leaving larvae outcompeted because of the increased rapidity of algal growth due to an abundance of sunlight. Therefore, only resulting in growth on one tile at log of velocity -1.65 m/s. High velocity sites resulted in growth at all four tiles with the highest specimen count of fourteen at log of velocity -0.95 m/s. Discussion and Observations Artificial reefs are being utilized because of ocean acidification and warm temperatures that have caused loss of natural reef habitats so it is important to understand whether these reefs can mimic natural reefs and provide similar habitats. 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Since this study is based on settlement and colonization and overall growth I suggest this study be done in the summer months, starting in June. This will ensure maximum settlement and growth of epibentic organisms. If I had more time to conduct this study than the allotted one semester, results would possibly have shown a peak of growth rate in July as these organisms prefer summer months. There were a few complications with this research study. The first was a complication with my funding from the school. This took about two months to receive the funding, order the supplies and receive the purchase order. Although this was quite the complication I collected data with available resources. Hanging the tiles on cleats instead of drilling them into the side of the dock was another challenging aspect of this study because in the zone marked as high velocity the water currents were making the tiles sway while tiles at the slow velocity zone were still because it was in a more stagnant location. Other complications pertaining to this project are predators of epibenthic growth, for example chiton. Chitons are small organisms that would resemble a bug of the ocean. These organisms consist of a hard shell for protection and live in crevices of rock structures; the natural stone tiles make a perfect habitat for these creatures. With chiton preying on organisms that are being studied in this research such as bryozoans, this makes it especially difficult to collect data as they are consuming them as they settle. 12 Figure 7. A chiton crawling on a piece of live rock. If I were to conduct this research in the future I would use different material such as terracotta because epibenthic larvae hide in the crevices of the stone tiles making them hard to count for. This experiment would also be setup at another floating dock that I have permission to drill into. In the future I would also apply for grants/funding months before setting up this experiment to ensure I had the most time possible that is needed for an in depth research study such as this one. Conclusion The Inlet Harbor boating docks provide a diverse marine environment to study epibenthic colonization and settlement of epibenthic marine invertebrates. This site in Ponce Inlet, Florida gives us a better understanding of how docks create an artificial reef and how we are able to use water velocity data as well as similar materials to build new artificial reef sites in Volusia County. Artificial reefs as well as natural reefs are relevant to our needs. Seafood is a large contributor to human needs whether economically or food based. With artificial reef projects underway we are contributing to oceanic habitats, nurseries, as well as a food source for 13 crustaceans and fishes that we consume on a daily basis. Further research studies in this area for a long period of time will also result in an understanding for ecological succession patterns and abundance of diversity. 14 Works Cited Carter, A., and S. Prekel. 2008. Benthic colonization and ecological successional patterns on a planned nearshore artificial reef system in Broward County, SE Florida. Marine Science & Biological Research 1209-1213. Docking Report Manuel: Guide to Fouling Organisms and Instructions Regarding the Docking Report. Bureau of Ships, Navy Department, Washington, D.C. USA. Dunstan, I. 1984. Marine Fouling at HMAS Stirling, Western Australia. Report MRL-R-914. Department of Defense, Defense Science and Technology Organisation, Materials Research Laboratories, Melbourne, Victoria. Hunter, W. R., M. Sayer. Comparative effects of habitat complexity in faunal assemblages of north temperate, artificial and natural reefs. ICES Journal of Marine Science 66: 691-698. Keough, M. J. 1984. Dynamics of the epifauna of the bivalve Pinna bicolor: interactions among recruitment, predation, and competition. Ecology 65: 677-688. McKinney, F. K. 2007. The Northern Adriatic Ecosystem: Deep Time in a Shallow Sea. Columbia University Press, Chinchester, New York, USA. Osman, R. W. 1977. The Establishment and Development of a Marine Epifaunal Community. Ecological Monographs 47: 37-63. Otsuka C. M., Dauer D. M. 1982. Fouling Community Dynamics in Lynnhaven Bay, Virginia. Estuaries Coasts 5:10-22. Pechenik, J. A. 1999. On the advantages and disadvantages of larval stages in benthic marine invertebrate life cycles. Marine Ecology Progress Series 177: 269-297. Rodriguez, S. R., F. P. Ojeda, and N. C. Inestrosa. 1993. Settlement of benthic marine invertebrates. Marine Ecology Progress Series 97:193-207. Speight, M. and P. Henderson. 2010. Marine Ecology: Concepts and Applications. John Wiley & Sons, Ltd, West Sussex, UK. Young, G. H. 1943. Twelve Months’ Fouling Record at North Florida Test Service Location. Mellon Institute of Industrial Research. Ponce Inlet, Florida, USA.