Mississippi lowland forests

Water is running nearly half a meter above tidal predictions today — not an astronomical tide, but a wind-driven setup surge pushing Gulf-influenced water inland through the estuarine bayous and drainage canals that ring this city. This is the kind of event that looks unremarkable on a gauge but carries outsized ecological consequences: warm, nutrient-saturated water from impaired canals backs up against the incoming surge, reducing circulation and stripping oxygen from a system that is already officially failing to meet its designated uses. It is July, and the compounding could not come at a worse time.The landscape sits in a topographic bowl maintained by pumps, and the bayou network — Bayou Bienvenue, Bayou St. John, the Lake Pontchartrain drainage canals — has nowhere to drain when southerly winds stack water at the coast. The result is a slow suffocation: warm, oxygen-depleted water pools in the shallows and backwaters of the Southern Holocene Meander Belts, a landscape shaped over millennia by the Mississippi's lateral wandering and now deeply altered by levees, pumping infrastructure, and chronic nutrient loading. The canals feeding into this system carry 303(d)-listed impairments — meaning regulators have formally acknowledged these waters cannot support their designated biological uses — yet they remain the primary drainage network for a major metropolitan area.It is precisely now — in the weeks following spring spawning — that juvenile fish are most physiologically vulnerable to dissolved oxygen crashes. Larvae and juveniles of estuarine species like Gulf menhaden, spotted seatrout, and bay anchovy have limited mobility and cannot easily escape hypoxic pockets the way adults can. A surge event that would be manageable in a healthy, well-flushed estuary becomes a trap in a canal system where water exchange is already impeded. The Mississippi Alluvial Plain has long supported some of the most productive estuarine nursery habitat in North America, but that productivity depends on the pulsed exchange between fresh and brackish water that these surge events now distort rather than facilitate.Indigenous communities of this delta — Houma, Chitimacha, Choctaw — read these same wind-tide signals for generations. They knew when persistent southerly weather would push brackish water into the interior marshes, and they moved accordingly, driving fish into shallower refugia or timing harvests to the rhythms of that pulsed intrusion. That ecological knowledge was embedded in seasonal practice precisely because these events were predictable in character, if not in exact timing. What has changed is not the wind, but the baseline: warmer water temperatures, higher ambient nutrient loads, and a drainage system so heavily engineered that the natural buffering capacity of the Mississippi lowland forests — the swamp forests dominated by bald cypress (Taxodium distichum) and common buttonbush (Cephalanthus occidentalis) that once absorbed surge energy and filtered nutrients — has been largely severed from the active hydrological network.The surge will recede, likely within a day or two as winds shift. But each summer episode like this, layered on top of persistent nutrient impairment and a warming temperature baseline, erodes a little more of the resilience that remains. The threshold to watch is whether recurring hypoxic events begin to show up in the fish community data as suppressed recruitment cohorts — years where a spring's worth of spawning effort simply disappears from the population record. That signal can take years to become legible in monitoring data, which is precisely why the real-time conditions visible today matter: this is where the recruitment failure starts, invisible in the canal water, long before it becomes a number in a stock assessment.

Chinese tallow is fruiting across the city's impaired bayous, with seed set confirmed in early July. This invasive shrub thrives in the nutrient-rich runoff of degraded waterways, outcompeting native buttonbush that is just beginning to bloom this week along canal margins starved of suitable seedbed.Introduced to the region as a soap crop in the eighteenth century, Chinese tallow has become a persistent ecological problem. Even after the parent trees are removed, its persistent litter continues to suppress native regeneration — a slow legacy that outlasts the plant itself. The current fruit set suggests another season of dispersal across already-compromised habitat.

The Carrollton Water Plant discharged chlorine at twenty-three times its legal limit this spring—a surge that coincides precisely with the period when larval fish are most vulnerable to chemical stress. The violation persists across quarters, a pattern baked into the operational data.In this reach of the Mississippi Alluvial Plain, the river both feeds and drains the city—a closed loop that amplifies any contamination. Of the ten water bodies in near proximity, seven are already on the federal impaired list. The chlorine spike is not an outlier; it is part of a steady pattern of exceedances. Recovery here will require more than seasonal improvement.

The air near Faubourg St. John sits heavy and still in summer, the kind of heat that flattens everything into shade. Along fences, chain-link and wooden both, and scrambling up into the lower branches of live oaks, passion vine grows in dense curtains of lobed leaves. Watch the open sunny edges of that vine. A Gulf fritillary will find it.The Gulf fritillary is a medium-sized butterfly, bright orange on the upper wings with black margins and white spots, silver-spangled underneath. It moves through the neighborhood in a loose, unhurried glide, but when a female locates passion vine, her behavior changes. She lands briefly, drums her forelegs against a leaf surface, and moves on, then returns, then lands again. She is tasting the plant through chemoreceptors in her feet, confirming the chemistry before she commits. When she is satisfied, she curves her abdomen and places a single pale yellow egg on a tendril, a leaf edge, or a stem. One egg, then she moves to another part of the vine. She rarely clusters them. The caterpillars that hatch are aggressive feeders, and spacing the eggs reduces competition between siblings on the same plant.Passion vine is the only plant Gulf fritillary caterpillars can eat. The relationship is specific and non-negotiable. The vine produces compounds called cyanogenic glycosides, which are toxic to most insects, but Gulf fritillary caterpillars not only tolerate them, they sequester the compounds in their own tissues, making themselves unpalatable to birds. The caterpillars are vivid orange and black, advertising this fact. A bird that tries one learns quickly. The adult butterflies carry some of that chemical protection too, absorbed during their time as caterpillars. The passion vine, for its part, has not been entirely passive in this arrangement. Some species produce extrafloral nectaries, small glands on the leaves and stems that secrete sugar, which attract ants. Ants patrolling for that sugar will attack caterpillars and other herbivores. Whether the vine benefits more from that ant activity than it loses to the fritillary caterpillars is a question without a clean answer. Both are happening at once.Summer is the peak of Gulf fritillary activity in New Orleans. Multiple generations cycle through between spring and the first cool weather of autumn. A caterpillar hatches, feeds for two to three weeks, pupates in a chrysalis that looks remarkably like a dried brown leaf, and emerges as an adult in roughly ten days. The adults nectar broadly, visiting lantana, ironweed, and whatever else is flowering in the heat, but reproduction always comes back to the passion vine. Females will fly considerable distances to find it, and in urban neighborhoods like this one, a single well-established vine on a fence can anchor a local population. The vine spreads aggressively in the Gulf Coast climate, which works in the fritillary's favor. Where the vine goes, the butterfly follows.Other species move through this same patch of vine. Brown anoles, an invasive species established throughout the urban New Orleans landscape, hunt from the leaf surfaces and stems. They eat small insects, and caterpillars small enough are fair targets, though the fritillary's chemical defenses offer some protection as the caterpillar grows. Spinybacked orbweavers string webs across the vine's gaps, waiting for anything that flies through. Green anoles hunt from higher up. The vine is a structure as much as a plant, a physical scaffold that organizes a small community of predators, prey, and visitors.If you are near any fence line or garden edge with dense vining growth, look at the leaf undersides and the tendrils. The eggs are small, ribbed, and pale yellow, easy to miss. The caterpillars are harder to miss once they are a week old, orange with black spines, moving steadily along a stem. And somewhere above the vine, if the sun is out, a fritillary is probably circling.

Mississippi Kites are nesting throughout the city this spring—over fifty sightings from City Park south to Plaquemines Parish since late April mark one of the most robust urban breeding seasons in recent memory. The adults are in full hunting mode now, diving through the humid air above streets and rooftops to snatch dragonflies on the wing and carry them back to their nestlings in the canopy.A generation ago, these graceful raptors were rare nesters in New Orleans itself. Their shift into street trees and park oaks is tied directly to the post-Katrina replanting effort: as the city rebuilt its urban forest over the past two decades, the kites followed, finding in those younger trees the combination of nesting cover and open airspace they need. What once seemed like unlikely colonization now reads as ecological recovery—the city's green infrastructure becoming suitable raptor habitat almost by design.

The air hangs thick near Faubourg St. John this morning, heavy with the promise of another summer day. Chinese tallow trees bloom in clusters along the water's edge, their small white flowers releasing a faint sweetness into the humid air. If you're inside, step out now and let the weight of this Louisiana summer settle on your shoulders.Among the elderberry and hackberry, where the invasive brown anoles dart between branches, a different drama unfolds. Monarch butterflies move through this landscape with purpose, their orange and black wings catching the early light. These threatened travelers carry an ancient urgency: they must find milkweed. The monarchs that pass through here in summer are part of the northern breeding generation, females heavy with eggs that can only develop on one type of plant. They taste leaves with their feet, searching for the bitter compounds that signal safety for their young. When a monarch caterpillar hatches, it will eat nothing but milkweed. The plant's toxic sap flows into the caterpillar's tissues, making both larva and adult butterfly poisonous to most predators.Milkweed plants grow quietly in the spaces between the more obvious trees. Their broad leaves collect morning dew that will burn off as the day heats up. The relationship between monarch and milkweed spans the butterfly's entire life cycle. Adult monarchs sip nectar from milkweed flowers when they bloom, but the real dependence runs deeper. Female monarchs lay single eggs on the undersides of milkweed leaves, one per plant when possible. The eggs are tiny, cream-colored domes barely visible against the leaf surface. Within days, a caterpillar emerges and begins eating the leaf that held its egg. It will consume nothing else for the next two weeks, growing through five distinct stages, each requiring a larger leaf surface. The caterpillar's black, white, and yellow stripes advertise its toxicity to birds and other predators. When ready to pupate, it wanders away from the milkweed to form its jade-green chrysalis, often on nearby elderberry or hackberry branches. The adult that emerges carries the milkweed's chemical protection in its wing scales and body tissues.This summer generation faces particular challenges. The heat that makes morning air shimmer above the pavement also stresses both butterfly and plant. Milkweed leaves can wilt in the afternoon sun, reducing their nutritional value just when caterpillars need them most. The monarchs that successfully breed here will produce the generation that attempts the long flight south to Mexico in fall. Their success depends on finding enough healthy milkweed plants to support egg-laying through the summer months. Each female may lay several hundred eggs over her lifetime, but only a fraction will survive to adulthood. The summer heat presses down on leaves and wings alike, creating the conditions where this ancient partnership either flourishes or fails.The Chinese tallow flowers release their scent into air that barely moves. Somewhere above, a monarch tests the wind with wings that carry the chemical signature of the milkweed it knew as a caterpillar.

The water along Faubourg St. John catches the late afternoon light, its surface barely stirring in the humid air. Pecan and live oak branches hang low over the canal edges, their early summer leaves casting shifting patches of shade across the shallow margins. Step outside if you can. The air carries the dense sweetness of elderberry blooms and the mineral scent of warm water.A yellow-crowned night heron stands motionless in knee-deep water near the bank. Its stocky body balances on thick yellow legs, neck coiled like a spring. The bird's crown shows the pale streaks that give it its name, and its dark eyes scan the water with mechanical precision. Unlike its black-crowned cousin, this heron hunts by day during nesting season, when the energy demands of feeding young override its usual nocturnal habits. It steps forward once, pauses, steps again. Each movement deliberate and measured.The shallow waters here concentrate exactly what the heron needs. Mullet cruise the warm margins, their silver backs breaking the surface as they feed on algae and detritus. Small blue crabs scuttle between submerged roots of water oak, their movements sending tiny clouds of sediment into the water column. The heron's thick bill can crack crab shells with a single snap, and its wide gape easily accommodates fish up to six inches long. During early summer, these prey species gather in the shallows to spawn and feed, creating dense concentrations that make hunting efficient. The canal's edges, warmed by sun and sheltered by overhanging branches, become feeding corridors that support not just this heron but the snowy egrets, little blue herons, and green herons that share these waters.The heron strikes. Its neck unfolds with startling speed, bill stabbing down and emerging with a struggling crab. The bird tosses its head back, adjusts the prey's position, and swallows. Within seconds, it has resumed its statue-like pose. This efficiency matters now because somewhere in the canopy above, likely in the fork of a live oak or the crown of a mature pecan, this bird's mate tends eggs or newly hatched chicks. The pair will make dozens of these hunting trips each day, ferrying protein back to the nest. The canal's abundance supports this cycle, its shallow margins serving as both nursery for prey species and hunting ground for the predators that depend on them. Listen for the soft splash when the heron steps forward again, and notice how the water settles into perfect stillness around its legs.