The Bronx: A Thriving River Runs Through It

Dr. Joseph W. Rachlin, Professor of Biological Sciences and director of the Laboratory for Marine and Estuarine Research (LaMER) at Lehman College, reports on a study of the Bronx River’s surprising state of health.

Professors Joseph Rachlin and Barbara Warkentine with Doctoral student Linda Lalicata (center).

One warm summer day this June, I carefully picked my way through the rubble littering the shore at the mouth of the Bronx River, watching the incoming tide push its way past the Krasdale food plant. In spite of the industrial wasteland all around, I knew new life was being born.

On that afternoon I watched several pairs of horseshoe crabs come ashore to mate in the pebbly sand. The larger female, with the male attached to her abdomen, buried herself and deposited her instantly fertilized eggs. Then they glided back past abandoned tires and rusting truck chassis and into the depths. The eggs would hatch at the next new moon.

How many city residents have witnessed this event, or are even aware of its cyclical occurrence? How much of the beauty and mystery of this river is missed because of the abandoned debris that blights its shoreline? The quality and diversity of life in this estuarine portion of the Bronx River are treasures about to be rediscovered once the long-awaited process of restoration and reclamation begins.

For two years, I have led a small scientific team that includes Dr. Barbara Warkentine of SUNY Maritime (a Lehman College alumna) and several CUNY students. The conclusions we have reached in our study of the river’s estuary may surprise: despite appearances, the river is thriving and serves as a breeding ground and nursery for more than a dozen species of fish and other aquatic organisms, including shrimp, horseshoe crabs and blue crabs. Fish species include striped bass, mossbunker, bluefish, gizzard shad, killifish, silversides, and flounder. And this summer we discovered the presence of two new fish species in the river, the naked goby and the seaboard goby.

The Bronx River’s original source, in Westchester County, is now part of the Kensico Reservoir system. With completion of the Kensico Dam in 1915, its flow was reduced by about a quarter, and its main tributary below the dam, Davis Brook, became its new source. The Bronx River travels south for approximately 23 miles to the East River, between Hunts Point and Clasons Points. The course of the river at the dam’s base starts at an elevation of 238 feet above sea level and gently drops to a level of seven feet at its mouth.

The Bronx River Parkway, a 15-mile, four-lane roadway, was built between 1916 and 1925. This limited-access parkway is protected on both sides by broad bands of parkland and follows the course of the river. The road was designed to cause minimum disturbance to the landscape, but during construction the river’s original course was significantly straightened to reduce local flooding.

The old Delancy Dam and waterfall in River Park at the southern boundary of the Bronx Zoo is the northern-most incursion of marine and estuarine fauna. For its entire length above the falls the river is completely freshwater, with appropriate freshwater flora and fauna. Below this point, as it flows through the south Bronx, the river becomes increasingly more saline and tidally influenced.

Over the years, neglect and abandonment of commercial establishments have led to marked degradation along the estuarine shoreline. Worse, this industrialization effectively cut the riverbanks off from local residents. Only in the last few years has awareness of the value of the river emerged, along with growing desire for public stewardship.

Congressman José Serrano, whose district includes the Bronx River estuary, worked with Governor Pataki to secure federal funds both for restoration and educational studies. Admini-stered by the National Oceanic and Atmospheric Administration (NOAA) as part of its estuary restoration program, these funds are supporting projects designed to improve the shoreline, increase the habitat and educate the community about this valuable natural resource.

Jointly sponsored by NOAA, the City Parks Foundation and Partnership for Parks, our team (which included Lehman’s Dr. Antonios Pappantoniou) has focused on characterizing estuarine fauna and flora, especially on the population dynamics and resource partitioning of fish species.

Most notably, our findings reveal the presence of sensitive indicator species, like sea anemones and oysters, as well as a high diversity of organisms. This points to good water quality despite years of neglect and dumping. Local fishermen regularly catch fish and blue crab in the river and report consuming them without ill effects.

This August, the team took samplings from the 46-foot SUNY Maritime research vessel Privateer during a bloom of dinoflagellates in the vicinity of Lafayette Avenue. The heavy concentration of this microorganism—as high as 17,000 cells per milliliter—turned the river the color of red wine, a condition sometimes called the “red tide” when it occurs off the Jersey Shore. Dinoflagellate blooms temporarily lower the water’s dissolved oxygen, which causes stress for fish and other aquatic organisms.

Mating horseshoe crabs

Less than a week later, the dinoflagellate cell count in this section had already dropped to 5,000 cells per milliliter, indicating that the condition was abating. Five days after that, it was virtually over.

Despite these occasional occurrences, the river is a prime candidate for restoration. It is home not only to aquatic life but also to a variety of shore birds such as egrets, cormorants, blue herons, swans, mallard ducks, ibis, plovers, sandpipers, and a variety of gulls.

Unfortunately, community residents are unacquainted with this rich fauna because access to the shore is severely restricted, especially on the estuary’s west bank.

A goal of the restoration efforts is to provide increased access to this marvelous opportunity for community enjoyment. With restoration efforts and cleanup, the river can become a place to find both quality boating and a strong recreational fishery. It can also serve as a living resource for the development of school curricula on aquatic biology and environmental stewardship.

Our CUNY/SUNY collaboration will continue. We are currently awaiting approval of our request for additional NOAA and Wildlife Conservation Society funding that will allow us to extend our study to the freshwater Bronx River. The data and species collected by the team will be housed at Lehman College’s new LaMER facility as a repository for future research and educational applications. Prime among these applications will be the creation of a Comprehensive Faunal and Floral Field Guide to the Bronx River for teachers, students, and community organizations in the borough.