Scallop spat

Well, yesterday was the last spat collector day of the season... Spat collectors, essentially mesh bags suspended in the water column, collect larval mollusks, crustaceans, squirts, and sometimes even fish... We use them to track scallop settlement throughout the Peconic Bays, in order to see approximate numbers and areas where they are being transported... Towards the end of the season, we do visual benthic surveys along transects at the spat collector locations to see if what we are catching in the nets is translating to the bottom... In other words, if we have a location where we get alot of spat in the bags, but no seed on the bottom when we do our visual surveys, we can assume that there is some source of high post settlement mortality, which in many cases is predation... I digress from the subject... The collectors are collected every 6 weeks and there are 2 sets which are off-set 3 weeks apart to ensure scallop spat that may be too small one one set should show up on the second set of bags...
Again, yesterday was the last day of the season for our spat bags, and surprisingly, we were still finding scallop spat, at 2-3 mm. On Wednesday we saw similar numbers of scallops... What does this mean? well it would seem that these scallops were spawned sometime in October... Scallop larvae usually spend around 2 weeks in the water column before settlement, and since these bags went out in October, it can be assumed that these scallops were spawned late September/early October, further evidence for fall spawning in bay scallops in NY waters... Is this related to warmer water temperatures later in the season? Perhaps, but I haven't investigated that avenue... It is just very exciting news for the scallop population, a seemingly steady spawn throughout the entire season, and even continued spawning through the fall... Yes, the number of spat on these last few collectors have not been as high as those during the summer, according to my professor, these are the highest numbers he's seen collected this late in the season over the course of the past few years... Further, in visual surveys, we are finding higher numbers of seed than ever before, although still much lower scallop densities than historic numbers.... Either way, its seems to be good news for the scallops, and good news for the countless people that have been working hard to restore bay scallop populations...

A different project:

While the focus of this blog will be concentrating the various aspects of my current graduate research, I wanted to make a small diversion to some research I did a few years ago with hard clams and eelgrass. I did benthic surveys for eelgrass abundance and hard clam densities in Shinnecock and Quantuck Bays on Long Island. While I only found 14% of the sites to have eelgrass, 67% of eelgrass sites had hard clams present, and only 33% of all other sites had hard clams present. Further, the densities of hard clams in eelgrass sites were double the densities outside of eelgrass. The reasons for this have been greatly explored in the literature, most often that below ground biomass of eelgrass offers a refuge from predation by crabs and whelks. However, little work ha been done to determine the impacts hard clams have on eelgrass. I was able to show that the addition of one hard clam to a quadrat of eelgrass (the equivalent of 16 hard clams per square meter) increased the eelgrass productivity (growth) about as much as a commercial fertilizer via nutrient additions. How? Hard clams filter the water column of phytoplankton and small zooplankton, and then repackage those as nutrients released to the sediments, which the eelgrass then uses for growth. It seems that there is an interactive relationship between the hard clams and eelgrass. I just submitted this work for publication in the Marine Ecology Progress Series, and if it gets accepted, it will be my first publication.

So a teacher I worked with put this article in the school district newspaper...

Gardiner Manor Students Participate in University Research Project

Gardiner Manor students assisted Marine Biologist John carroll in his quest to solve the mystery of the vanishing Long Island scallop. Inspired by Mrs. Forman's students, who first became involved, Kids for Saving The Earth Club and the Gardiner Manor Service Club members put in tireless hours last year threading green ribbon onto plastic mats. These artificial eelgrass mats were submerged in Hallock Bay (on the notrth shore of Long Island near Orient Point) in hopes that they would attract various aquatic animals and provide a safe habitat for the scallops.

Threading the mats was a tedious job and it took a lot of patience! Mr. Carroll has since reported that small fish such as silverslides and killifish quickly colonized the "eelgrass", along with pipefish, small flounder, sea bass, grass shrimp and numerous species of crabs. Best of all, the scallop population is thriving! Visit John Carroll's website at http://zostera.blogspotcom/ for more of the scientific details.

UPDATE!!!

So we went through my suction samples yesterday, and I found 3 juvenile scallops in total... Nothing spectacular, but it does mean that there was some natural recruitment, which is exciting... Another interesting thing, which was expected, was that the star shaped patches (the patches with the most perimeter) had higher amounts of drift algae and larger numbers of predators, although I haven't run any tests for significance yet... This is good news though, supports the edge effect theory...

Project Break Down

Well, I took my grass mats out of the water last week. Not only did I remove my scallops, I suction dredged the mats and took them out as well. I haven't finished measuring the scallops or measured the dry weights, but soon I hope to have those results worked out. Tomorrow I am going to finally go through the suction samples and next week I am going to visually inspect the mats to see if I missed any juvenile scallops, predators, etc and then stow them for next year. One exciting thing I did notice though, while shucking my scallops I noticed that many of them still had gonads. Usually the gonads are spent this time of year, but for many of my scallops, they were not. This might be due to water temperatures still being so warm, or may be mere coincidence. Whatever the case, this supports the idea that there is a late fall spawn for bay scallops in Long Island. I will update once I have the data!

To start things off

Well, I realize that I started this blog and never put any updates into it... Oops... It has been a busy summer filled with long days on and in the water, but with some excitement as well... I finally put my artificial seagrass mats out in the field in July, which was a very exciting day... The idea behind the artificial mats is that the local estuarine habitats are changing from once dense meadows of eelgrass to small isolated patches... Nobody is really sure the impacts of this changing habitat, and rather than disturb the already stressed existing eelgrass, we chose to make our own artificial mats... This also allows us to make them all the same, in terms of number of shoots, blades, etc :



Once they were in the water, they looked great... The ribbons stood upright... They were quickly colonized by small fish like silversides and killifish... Soon the mats were colonized by other fish, like pipefifh, tautogs, cunner, and even some small flounder and sea bass, and many invertebrates, including grass shrimp, mud crabs, spider crabs, blue crabs and whelks... The mats also experienced epiphytic algal and bacterial growth and also received a fair amount of drift algae... All in all, it was very impressive and far exceeding my expectations:



I placed scallops out in these mats, 10 to a bag, to prevent predation, in order to measure scallop growth... They have been growing well, around 25 millimeters (around one inch) in 8 weeks time... These are about triple the size of when I put them in (averaging around 11-12 mm, and now between 35-40mm)... These are very exciting results, although I don't have pictures right now to show... I attempted a predation experiment with tethers, however, this wasn't very successful, as I had extremely high mortality that I could not attribute to predation...


I have also worked on spat collectors located in various locations throughout the Peconic Estuary, with some fairly exciting results... This is part of a large bay scallop restoration effort undertaken by Suffolk County and the Cornell Cooperative Extension of Suffolk County... This effort includes researches from various parts of Long Island, as well as dozens of local volunteers, to spawn scallops in captivity, grow them out in field settings and hang millions of them in lantern nets in close proximity in the hopes that having that many close together will enable them to spawn in the wild and allow larvae to recruit throughout the bays... This is the first full year with the high density of scallops in these lantern nets, although various other spawner sanctuaries have been set up for the past few years... All the data is still coming in, so nothing concrete yet, but there are some real positive signs that this type of method might be working...

Finally, I am also investigating the effectiveness of alternative habitats... I have looked at free planted and tethered scallops in alternative habitats for the past 2 summer seasons... Stay tuned for the results...